Issue published April 1, 2014 Previous issue | Next issue
- Volume 124, Issue 4
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On the cover: Sonic hedgehog signaling
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Reviews
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Abstract
Age-related macular degeneration (AMD) is a common cause of visual loss in the elderly, with increasing prevalence due to increasing life expectancy. While the introduction of anti-VEGF therapy has improved outcomes, there are still major unmet needs and gaps in the understanding of underlying biological processes. These include early, intermediate, and atrophic disease stages. Recent studies have assessed therapeutic approaches addressing various disease-associated pathways, including complement inhibitors. Drug-delivery aspects are also relevant, as many agents have to be administered repeatedly. Herein, relevant pathogenetic factors and underlying mechanisms as well as recent and potential therapeutic approaches are reviewed.
Authors
Frank G. Holz, Steffen Schmitz-Valckenberg, Monika Fleckenstein
×Abstract
Early demonstrations that mice could be tolerized to transplanted tissues with short courses of immunosuppressive therapy and that with regard to tolerance to self, CD4+FOXP3+ regulatory T cells (Tregs) appeared to play a critical role, have catalyzed strategies to harness FOXP3-dependent processes to control rejection in human transplantation. This review seeks to examine the scientific underpinning for this new approach to finesse immunosuppression.
Authors
Herman Waldmann, Robert Hilbrands, Duncan Howie, Stephen Cobbold
×Abstract
It is increasingly evident that cancer results from altered organ homeostasis rather than from deregulated control of single cells or groups of cells. This applies especially to epithelial cancer, the most common form of human solid tumors and a major cause of cancer lethality. In the vast majority of cases, in situ epithelial cancer lesions do not progress into malignancy, even if they harbor many of the genetic changes found in invasive and metastatic tumors. While changes in tumor stroma are frequently viewed as secondary to changes in the epithelium, recent evidence indicates that they can play a primary role in both cancer progression and initiation. These processes may explain the phenomenon of field cancerization, i.e., the occurrence of multifocal and recurrent epithelial tumors that are preceded by and associated with widespread changes of surrounding tissue or organ “fields.”
Authors
G. Paolo Dotto
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Hindsight
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Abstract
Nearly two decades ago, we evaluated ten patients with obstructive sleep apnea (OSA). We determined that alarming nocturnal oscillations in arterial pressure and sympathetic nerve activity (SNA) were caused by regulatory coupling and neural interactions among SNA, apnea, and ventilation. Patients with OSA exhibited high levels of SNA when awake, during normal ventilation, and during normoxia, which contributed to hypertension and organ damage. Additionally, we achieved a beneficial and potentially lifesaving reduction in SNA through the application of continuous positive airway pressure (CPAP), which remains a primary therapeutic approach for patients with OSA. With these results in hindsight, we herein discuss three concepts with functional and therapeutic relevance to the integrative neurobiology of autonomic cardiovascular control and to the mechanisms involved in excessive sympathoexcitation in OSA.
Authors
François Abboud, Ravinder Kumar
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Commentaries
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Abstract
The metastatic spread of tumor epithelial cells accounts for over 90% of cancer-specific mortality; however, the molecular mechanisms that govern tumor spread and distant recolonization remain unclear. In this issue of
JCI , Rokavec and colleagues shine light on this murky aspect of tumor biology by focusing through the lens of microenvironmental contributions, namely inflammation, as driving signals that set off a delicate, intracellular feedback loop among cytokine receptors, transcription factors and miRNAs. This study provides in vivo evidence and identifies molecular players behind the elusive switch that drives the epithelial-to-mesenchymal transition and the mesenchymal-to-epithelial transition.Authors
Julienne L. Carstens, Sara Lovisa, Raghu Kalluri
×Abstract
Genome-wide association studies (GWAS) have implicated
SCN10A , which encodes a nociceptor-associated voltage-gated sodium channel subunit, as a modulator of cardiac conduction; however, this role has traditionally been ascribed toSCN5A , which is highly expressed in cardiac muscle.SCN10A is believed to affect cardiac conduction either directly through cardiomyocytes or indirectly via intracardiac neurons. In this issue of theJCI , van den Boogaard and colleagues introduce a third possibility: that theSCN10A locus acts as an enhancer ofSCN5A gene expression. The authors demonstrate thatSCN10A expression is negligible within human and murine hearts, and that a T-box enhancer within theSCN10A locus drivesSCN5A expression within cardiomyocytes. This work reassertsSCN5A as the key determinant of cardiac conduction and highlights the importance of deciphering the functionality of coding versus noncoding regions when interpreting GWAS data.Authors
David S. Park, Glenn I. Fishman
×Abstract
Thromboinflammatory diseases result from the interactions of vascular endothelial cells, inflammatory cells, and platelets with cellular adhesion molecules, plasma proteins, and lipids. Tipping the balance toward a prothrombotic, proinflammatory phenotype results from multicellular activation signals. In this issue of the
JCI , Li et al. explore the regulation of heterotypic neutrophil-platelet contacts in response to TNF-α–induced venular inflammation with relevance to sickle cell disease (SCD).Authors
Gregory M. Vercellotti, John D. Belcher
×Abstract
Recent studies have demonstrated that insulin stimulates bone cells to produce and activate osteocalcin, an endocrine hormone that increases the efficiency of glucose metabolism through its actions on the pancreas and other peripheral tissues. In this issue of the
JCI , Wei and colleagues directly explore the contribution of insulin signaling in osteoblasts to the disturbances in whole-body glucose metabolism associated with a high-fat diet. In mice fed a high-fat diet, increased uptake of saturated fatty acids by the osteoblast accelerates the ubiquitination and degradation of the insulin receptor. In this setting, impairments in osteoblast insulin signaling reduce serum levels of undercarboxylated osteocalcin, which in turn exacerbate insulin resistance in muscle and white adipose tissue. These findings underscore the importance of insulin-responsive skeletal cells as components of a newly appreciated endocrine network critical for regulating global energy homeostasis.Authors
Ryan C. Riddle, Thomas L. Clemens
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Research Articles
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Abstract
The recent identification of multiple dominant mutations in the gene encoding β-catenin in both humans and mice has enabled exploration of the molecular and cellular basis of β-catenin function in cognitive impairment. In humans, β-catenin mutations that cause a spectrum of neurodevelopmental disorders have been identified. We identified de novo β-catenin mutations in patients with intellectual disability, carefully characterized their phenotypes, and were able to define a recognizable intellectual disability syndrome. In parallel, characterization of a chemically mutagenized mouse line that displays features similar to those of human patients with β-catenin mutations enabled us to investigate the consequences of β-catenin dysfunction through development and into adulthood. The mouse mutant, designated batface (
Bfc ), carries a Thr653Lys substitution in the C-terminal armadillo repeat of β-catenin and displayed a reduced affinity for membrane-associated cadherins. In association with this decreased cadherin interaction, we found that the mutation results in decreased intrahemispheric connections, with deficits in dendritic branching, long-term potentiation, and cognitive function. Our study provides in vivo evidence that dominant mutations in β-catenin underlie losses in its adhesion-related functions, which leads to severe consequences, including intellectual disability, childhood hypotonia, progressive spasticity of lower limbs, and abnormal craniofacial features in adults.Authors
Valter Tucci, Tjitske Kleefstra, Andrea Hardy, Ines Heise, Silvia Maggi, Marjolein H. Willemsen, Helen Hilton, Chris Esapa, Michelle Simon, Maria-Teresa Buenavista, Liam J. McGuffin, Lucie Vizor, Luca Dodero, Sotirios Tsaftaris, Rosario Romero, Willy N. Nillesen, Lisenka E.L.M. Vissers, Marlies J. Kempers, Anneke T. Vulto-van Silfhout, Zafar Iqbal, Marta Orlando, Alessandro Maccione, Glenda Lassi, Pasqualina Farisello, Andrea Contestabile, Federico Tinarelli, Thierry Nieus, Andrea Raimondi, Barbara Greco, Daniela Cantatore, Laura Gasparini, Luca Berdondini, Angelo Bifone, Alessandro Gozzi, Sara Wells, Patrick M. Nolan
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Interactions between platelets, leukocytes, and activated endothelial cells are important during microvascular occlusion; however, the regulatory mechanisms of these heterotypic cell-cell interactions remain unclear. Here, using intravital microscopy to evaluate mice lacking specific isoforms of the serine/threonine kinase AKT and bone marrow chimeras, we found that hematopoietic cell–associated AKT2 is important for neutrophil adhesion and crawling and neutrophil-platelet interactions on activated endothelial cells during TNF-α–induced venular inflammation. Studies with an AKT2-specific inhibitor and cells isolated from WT and
Akt KO mice revealed that platelet- and neutrophil-associated AKT2 regulates heterotypic neutrophil-platelet aggregation under shear conditions. In particular, neutrophil AKT2 was critical for membrane translocation of αMβ2 integrin, β2-talin1 interaction, and intracellular Ca2+ mobilization. We found that the basal phosphorylation levels of AKT isoforms were markedly increased in neutrophils and platelets isolated from patients with sickle cell disease (SCD), an inherited hematological disorder associated with vascular inflammation and occlusion. AKT2 inhibition reduced heterotypic aggregation of neutrophils and platelets isolated from SCD patients and diminished neutrophil adhesion and neutrophil-platelet aggregation in SCD mice, thereby improving blood flow rates. Our results provide evidence that neutrophil AKT2 regulates αMβ2 integrin function and suggest that AKT2 is important for neutrophil recruitment and neutrophil-platelet interactions under thromboinflammatory conditions such as SCD.Authors
Jing Li, Kyungho Kim, Eunsil Hahm, Robert Molokie, Nissim Hay, Victor R. Gordeuk, Xiaoping Du, Jaehyung Cho
×Abstract
Tumor endothelial marker 1 (TEM1; also known as endosialin or CD248) is a protein found on tumor vasculature and in tumor stroma. Here, we tested whether TEM1 has potential as a therapeutic target for cancer immunotherapy by immunizing immunocompetent mice with
Tem1 cDNA fused to the minimal domain of the C fragment of tetanus toxoid (referred to herein as Tem1-TT vaccine). Tem1-TT vaccination elicited CD8+ and/or CD4+ T cell responses against immunodominant TEM1 protein sequences. Prophylactic immunization of animals with Tem1-TT prevented or delayed tumor formation in several murine tumor models. Therapeutic vaccination of tumor-bearing mice reduced tumor vascularity, increased infiltration of CD3+ T cells into the tumor, and controlled progression of established tumors. Tem1-TT vaccination also elicited CD8+ cytotoxic T cell responses against murine tumor-specific antigens. Effective Tem1-TT vaccination did not affect angiogenesis-dependent physiological processes, including wound healing and reproduction. Based on these data and the widespread expression of TEM1 on the vasculature of different tumor types, we conclude that targeting TEM1 has therapeutic potential in cancer immunotherapy.Authors
John G. Facciponte, Stefano Ugel, Francesco De Sanctis, Chunsheng Li, Liping Wang, Gautham Nair, Sandy Sehgal, Arjun Raj, Efthymia Matthaiou, George Coukos, Andrea Facciabene
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Aberrant expression of the secreted protein, acidic, cysteine-rich (osteonectin) (
SPARC ) gene, which encodes a matricellular protein that participates in normal tissue remodeling, is associated with a variety of diseases including cancer, but the contribution of SPARC to malignant growth remains controversial. We previously reported thatSPARC was among the most upregulated genes in cytogenetically normal acute myeloid leukemia (CN-AML) patients with gene-expression profiles predictive of unfavorable outcome, such as mutations in isocitrate dehydrogenase 2 (IDH2 -R172) and overexpression of the oncogenes brain and acute leukemia, cytoplasmic (BAALC ) and v-ets erythroblastosis virus E26 oncogene homolog (ERG ). In contrast,SPARC was downregulated in CN-AML patients harboring mutations in nucleophosmin (NPM1 ) that are associated with favorable prognosis. Based on these observations, we hypothesized thatSPARC expression is clinically relevant in AML. Here, we found thatSPARC overexpression is associated with adverse outcome in CN-AML patients and promotes aggressive leukemia growth in murine models of AML. In leukemia cells,SPARC expression was mediated by the SP1/NF-κB transactivation complex. Furthermore, secreted SPARC activated the integrin-linked kinase/AKT (ILK/AKT) pathway, likely via integrin interaction, and subsequent β-catenin signaling, which is involved in leukemia cell self-renewal. Pharmacologic inhibition of the SP1/NF-κB complex resulted inSPARC downregulation and leukemia growth inhibition. Together, our data indicate that evaluation ofSPARC expression has prognosticative value and SPARC is a potential therapeutic target for AML.Authors
Houda Alachkar, Ramasamy Santhanam, Kati Maharry, Klaus H. Metzeler, Xiaomeng Huang, Jessica Kohlschmidt, Jason H. Mendler, Juliana M. Benito, Christopher Hickey, Paolo Neviani, Adrienne M. Dorrance, Mirela Anghelina, Jihane Khalife, Somayeh S. Tarighat, Stefano Volinia, Susan P. Whitman, Peter Paschka, Pia Hoellerbauer, Yue-Zhong Wu, Lina Han, Brad N. Bolon, William Blum, Krzysztof Mrózek, Andrew J. Carroll, Danilo Perrotti, Michael Andreeff, Michael A. Caligiuri, Marina Konopleva, Ramiro Garzon, Clara D. Bloomfield, Guido Marcucci
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Background . The therapeutic resistance of pancreatic ductal adenocarcinoma (PDAC) is partly ascribed to ineffective delivery of chemotherapy to cancer cells. We hypothesized that physical properties at vascular, extracellular, and cellular scales influence delivery of and response to gemcitabine-based therapy.Methods . We developed a method to measure mass transport properties during routine contrast-enhanced CT scans of individual human PDAC tumors. Additionally, we evaluated gemcitabine infusion during PDAC resection in 12 patients, measuring gemcitabine incorporation into tumor DNA and correlating its uptake with human equilibrative nucleoside transporter (hENT1) levels, stromal reaction, and CT-derived mass transport properties. We also studied associations between CT-derived transport properties and clinical outcomes in patients who received preoperative gemcitabine-based chemoradiotherapy for resectable PDAC.Results . Transport modeling of 176 CT scans illustrated striking differences in transport properties between normal pancreas and tumor, with a wide array of enhancement profiles. Reflecting the interpatient differences in contrast enhancement, resected tumors exhibited dramatic differences in gemcitabine DNA incorporation, despite similar intravascular pharmacokinetics. Gemcitabine incorporation into tumor DNA was inversely related to CT-derived transport parameters and PDAC stromal score, after accounting for hENT1 levels. Moreover, stromal score directly correlated with CT-derived parameters. Among 110 patients who received preoperative gemcitabine-based chemoradiotherapy, CT-derived parameters correlated with pathological response and survival.Conclusion . Gemcitabine incorporation into tumor DNA is highly variable and correlates with multiscale transport properties that can be derived from routine CT scans. Furthermore, pretherapy CT-derived properties correlate with clinically relevant endpoints.Trial registration . Clinicaltrials.gov NCT01276613.Funding . Lustgarten Foundation (989161), Department of Defense (W81XWH-09-1-0212), NIH (U54CA151668, KCA088084).Authors
Eugene J. Koay, Mark J. Truty, Vittorio Cristini, Ryan M. Thomas, Rong Chen, Deyali Chatterjee, Ya’an Kang, Priya R. Bhosale, Eric P. Tamm, Christopher H. Crane, Milind Javle, Matthew H. Katz, Vijaya N. Gottumukkala, Marc A. Rozner, Haifa Shen, Jeffery E. Lee, Huamin Wang, Yuling Chen, William Plunkett, James L. Abbruzzese, Robert A. Wolff, Gauri R. Varadhachary, Mauro Ferrari, Jason B. Fleming
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Development of host protective immunity against
Mycobacterium tuberculosis infection is critically dependent on the inflammatory cytokine TNF. TNF signals through 2 receptors, TNFRp55 and TNFRp75; however, the role of TNFRp75-dependent signaling in immune regulation is poorly defined. Here we found that mice lacking TNFRp75 exhibit greater control ofM. tuberculosis infection compared with WT mice. TNFRp75–/– mice developed effective bactericidal granulomas and demonstrated increased pulmonary recruitment of activated DCs. Moreover, IL-12p40–dependent migration of DCs to lung draining LNs of infected TNFRp75–/– mice was substantially higher than that observed in WTM. tuberculosis –infected animals and was associated with enhanced frequencies of activatedM. tuberculosis –specific IFN-γ–expressing CD4+ T cells. In WT mice, TNFRp75 shedding correlated with markedly reduced bioactive TNF levels and IL-12p40 expression. Neutralization of TNFRp75 inM. tuberculosis –infected WT BM-derived DCs (BMDCs) increased production of bioactive TNF and IL-12p40 to a level equivalent to that produced by TNFRp75–/– BMDCs. Addition of exogenous TNFRp75 to TNFRp75–/– BMDCs infected withM. tuberculosis decreased IL-12p40 synthesis, demonstrating that TNFRp75 shedding regulates DC activation. These data indicate that TNFRp75 shedding downmodulates protective immune function and reduces host resistance and survival; therefore, targeting TNFRp75 may be beneficial for improving disease outcome.Authors
Roanne Keeton, Nasiema Allie, Ivy Dambuza, Brian Abel, Nai-Jen Hsu, Boipelo Sebesho, Philippa Randall, Patricia Burger, Elizabeth Fick, Valerie F.J. Quesniaux, Bernhard Ryffel, Muazzam Jacobs
×Abstract
Familial Alzheimer’s disease (FAD) is characterized by autosomal dominant heritability and early disease onset. Mutations in the gene encoding presenilin-1 (PS1) are found in approximately 80% of cases of FAD, with some of these patients presenting cerebellar damage with amyloid plaques and ataxia with unclear pathophysiology. A Colombian kindred carrying the PS1-E280A mutation is the largest known cohort of PS1-FAD patients. Here, we investigated PS1-E280A–associated cerebellar dysfunction and found that it occurs early in PS1-E208A carriers, while cerebellar signs are highly prevalent in patients with dementia. Postmortem analysis of cerebella of PS1-E280A carrier revealed greater Purkinje cell (PC) loss and more abnormal mitochondria compared with controls. In PS1-E280A tissue, ER/mitochondria tethering was impaired, Ca2+ channels IP3Rs and CACNA1A were downregulated, and Ca2+-dependent mitochondrial transport proteins MIRO1 and KIF5C were reduced. Accordingly, expression of PS1-E280A in a neuronal cell line altered ER/mitochondria tethering and transport compared with that in cells expressing wild-type PS1. In a murine model of PS1-FAD, animals exhibited mild ataxia and reduced PC simple spike activity prior to cerebellar β-amyloid deposition. Our data suggest that impaired calcium homeostasis and mitochondrial dysfunction in PS1-FAD PCs reduces their activity and contributes to motor coordination deficits prior to Aβ aggregation and dementia. We propose that PS1-E280A affects both Ca2+ homeostasis and Aβ precursor processing, leading to FAD and neurodegeneration.
Authors
Diego Sepulveda-Falla, Alvaro Barrera-Ocampo, Christian Hagel, Anne Korwitz, Maria Fernanda Vinueza-Veloz, Kuikui Zhou, Martijn Schonewille, Haibo Zhou, Luis Velazquez-Perez, Roberto Rodriguez-Labrada, Andres Villegas, Isidro Ferrer, Francisco Lopera, Thomas Langer, Chris I. De Zeeuw, Markus Glatzel
×Abstract
The use of pegylated interferon-α (pegIFN-α) has replaced unmodified recombinant IFN-α for the treatment of chronic viral hepatitis. While the superior antiviral efficacy of pegIFN-α is generally attributed to improved pharmacokinetic properties, the pharmacodynamic effects of pegIFN-α in the liver have not been studied. Here, we analyzed pegIFN-α–induced signaling and gene regulation in paired liver biopsies obtained prior to treatment and during the first week following pegIFN-α injection in 18 patients with chronic hepatitis C. Despite sustained high concentrations of pegIFN-α in serum, the Jak/STAT pathway was activated in hepatocytes only on the first day after pegIFN-α administration. Evaluation of liver biopsies revealed that pegIFN-α induces hundreds of genes that can be classified into four clusters based on different temporal expression profiles. In all clusters, gene transcription was mainly driven by IFN-stimulated gene factor 3 (ISGF3). Compared with conventional IFN-α therapy, pegIFN-α induced a broader spectrum of gene expression, including many genes involved in cellular immunity. IFN-induced secondary transcription factors did not result in additional waves of gene expression. Our data indicate that the superior antiviral efficacy of pegIFN-α is not the result of prolonged Jak/STAT pathway activation in hepatocytes, but rather is due to induction of additional genes that are involved in cellular immune responses.
Authors
Michael T. Dill, Zuzanna Makowska, Gaia Trincucci, Andreas J. Gruber, Julia E. Vogt, Magdalena Filipowicz, Diego Calabrese, Ilona Krol, Daryl T. Lau, Luigi Terracciano, Erik van Nimwegen, Volker Roth, Markus H. Heim
×Abstract
Targeted cancer therapies often induce “outlier” responses in molecularly defined patient subsets. One patient with advanced-stage lung adenocarcinoma, who was treated with oral sorafenib, demonstrated a near-complete clinical and radiographic remission for 5 years. Whole-genome sequencing and RNA sequencing of primary tumor and normal samples from this patient identified a somatic mutation,
ARAF S214C, present in the cancer genome and expressed at high levels. Additional mutations affecting this residue of ARAF and a nearby residue in the related kinase RAF1 were demonstrated across 1% of an independent cohort of lung adenocarcinoma cases. The ARAF mutations were shown to transform immortalized human airway epithelial cells in a sorafenib-sensitive manner. These results suggest that mutant ARAF is an oncogenic driver in lung adenocarcinoma and an indicator of sorafenib response.Authors
Marcin Imielinski, Heidi Greulich, Bethany Kaplan, Luiz Araujo, Joseph Amann, Leora Horn, Joan Schiller, Miguel A. Villalona-Calero, Matthew Meyerson, David P. Carbone
×Abstract
Background . X-linked hypophosphatemia (XLH) is the most common heritable form of rickets and osteomalacia. XLH-associated mutations in phosphate-regulating endopeptidase (PHEX) result in elevated serum FGF23, decreased renal phosphate reabsorption, and low serum concentrations of phosphate (inorganic phosphorus, Pi) and 1,25-dihydroxyvitamin D [1,25(OH)2D]. KRN23 is a human anti-FGF23 antibody developed as a potential treatment for XLH. Here, we have assessed the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity of KRN23 following a single i.v. or s.c. dose of KRN23 in adults with XLH.Methods . Thirty-eight XLH patients were randomized to receive a single dose of KRN23 (0.003–0.3 mg/kg i.v. or 0.1–1 mg/kg s.c.) or placebo. PK, PD, immunogenicity, safety, and tolerability were assessed for up to 50 days.Results . KRN23 significantly increased the maximum renal tubular threshold for phosphate reabsorption (TmP/GFR), serum Pi, and 1,25(OH)2D compared with that of placebo (P < 0.01). The maximum serum Pi concentration occurred later following s.c. dosing (8–15 days) compared with that seen with i.v. dosing (0.5–4 days). The effect duration was dose related and persisted longer in patients who received s.c. administration. Changes from baseline in TmP/GFR, serum Pi, and serum 1,25(OH)2D correlated with serum KRN23 concentrations. The mean t1/2 of KRN23 was 8–12 days after i.v. administration and 13–19 days after s.c. administration. Patients did not exhibit increased nephrocalcinosis or develop hypercalciuria, hypercalcemia, anti-KRN23 antibodies, or elevated serum parathyroid hormone (PTH) or creatinine.Conclusion . KRN23 increased TmP/GFR, serum Pi, and serum 1,25(OH)2D. The positive effect of KR23 on serum Pi and its favorable safety profile suggest utility for KRN23 in XLH patients.Trial registration . Clinicaltrials.gov NCT00830674.Funding . Kyowa Hakko Kirin Pharma, Inc.Authors
Thomas O. Carpenter, Erik A. Imel, Mary D. Ruppe, Thomas J. Weber, Mark A. Klausner, Margaret M. Wooddell, Tetsuyoshi Kawakami, Takahiro Ito, Xiaoping Zhang, Jeffrey Humphrey, Karl L. Insogna, Munro Peacock
×Abstract
Hereditary deafness affects approximately 1 in 2,000 children. Mutations in the gene encoding the cochlear gap junction protein connexin 26 (CX26) cause prelingual, nonsyndromic deafness and are responsible for as many as 50% of hereditary deafness cases in certain populations. Connexin-associated deafness is thought to be the result of defective development of auditory sensory epithelium due to connexion dysfunction. Surprisingly, CX26 deficiency is not compensated for by the closely related connexin CX30, which is abundantly expressed in the same cochlear cells. Here, using two mouse models of CX26-associated deafness, we demonstrate that disruption of the CX26-dependent gap junction plaque (GJP) is the earliest observable change during embryonic development of mice with connexin-associated deafness. Loss of CX26 resulted in a drastic reduction in the GJP area and protein level and was associated with excessive endocytosis with increased expression of caveolin 1 and caveolin 2. Furthermore, expression of deafness-associated
CX26 andCX30 in cell culture resulted in visible disruption of GJPs and loss of function. Our results demonstrate that deafness-associated mutations inCX26 induce the macromolecular degradation of large gap junction complexes accompanied by an increase in caveolar structures.Authors
Kazusaku Kamiya, Sabrina W. Yum, Nagomi Kurebayashi, Miho Muraki, Kana Ogawa, Keiko Karasawa, Asuka Miwa, Xueshui Guo, Satoru Gotoh, Yoshinobu Sugitani, Hitomi Yamanaka, Shioko Ito-Kawashima, Takashi Iizuka, Takashi Sakurai, Tetsuo Noda, Osamu Minowa, Katsuhisa Ikeda
×Abstract
Focal segmental glomerular sclerosis (FSGS) is a primary kidney disease that is commonly associated with proteinuria and progressive loss of glomerular function, leading to development of chronic kidney disease (CKD). FSGS is characterized by podocyte injury and depletion and collapse of glomerular capillary segments. Progression of FSGS is associated with TGF-β activation in podocytes; however, it is not clear how TGF-β signaling promotes disease. Here, we determined that podocyte-specific activation of TGF-β signaling in transgenic mice and BALB/c mice with Adriamycin-induced glomerulosclerosis is associated with endothelin-1 (EDN1) release by podocytes, which mediates mitochondrial oxidative stress and dysfunction in adjacent endothelial cells via paracrine EDN1 receptor type A (EDNRA) activation. Endothelial dysfunction promoted podocyte apoptosis, and inhibition of EDNRA or scavenging of mitochondrial-targeted ROS prevented podocyte loss, albuminuria, glomerulosclerosis, and renal failure. We confirmed reciprocal crosstalk between podocytes and endothelial cells in a coculture system. Biopsies from patients with FSGS exhibited increased mitochondrial DNA damage, consistent with EDNRA-mediated glomerular endothelial mitochondrial oxidative stress. Our studies indicate that segmental glomerulosclerosis develops as a result of podocyte-endothelial crosstalk mediated by EDN1/EDNRA-dependent mitochondrial dysfunction and suggest that targeting the reciprocal interaction between podocytes and endothelia may provide opportunities for therapeutic intervention in FSGS.
Authors
Ilse Daehn, Gabriella Casalena, Taoran Zhang, Shaolin Shi, Franz Fenninger, Nicholas Barasch, Liping Yu, Vivette D’Agati, Detlef Schlondorff, Wilhelm Kriz, Borje Haraldsson, Erwin P. Bottinger
×Abstract
Pathological remodeling of the extracellular matrix (ECM) by fibroblasts leads to organ failure. Development of idiopathic pulmonary fibrosis (IPF) is characterized by a progressive fibrotic scarring in the lung that ultimately leads to asphyxiation; however, the cascade of events that promote IPF are not well defined. Here, we examined how the interplay between the ECM and fibroblasts affects both the transcriptome and translatome by culturing primary fibroblasts generated from IPF patient lung tissue or nonfibrotic lung tissue on decellularized lung ECM from either IPF or control patients. Surprisingly, the origin of the ECM had a greater impact on gene expression than did cell origin, and differences in translational control were more prominent than alterations in transcriptional regulation. Strikingly, genes that were translationally activated by IPF-derived ECM were enriched for those encoding ECM proteins detected in IPF tissue. We determined that genes encoding IPF-associated ECM proteins are targets for miR-29, which was downregulated in fibroblasts grown on IPF-derived ECM, and baseline expression of ECM targets could be restored by overexpression of miR-29. Our data support a model in which fibroblasts are activated to pathologically remodel the ECM in IPF via a positive feedback loop between fibroblasts and aberrant ECM. Interrupting this loop may be a strategy for IPF treatment.
Authors
Matthew W. Parker, Daniel Rossi, Mark Peterson, Karen Smith, Kristina Sikström, Eric S. White, John E. Connett, Craig A. Henke, Ola Larsson, Peter B. Bitterman
×Abstract
The transcription factor SOX2 is an essential regulator of pluripotent stem cells and promotes development and maintenance of squamous epithelia. We previously reported that
SOX2 is an oncogene and subject to highly recurrent genomic amplification in squamous cell carcinomas (SCCs). Here, we have further characterized the function of SOX2 in SCC. Using ChIP-seq analysis, we compared SOX2-regulated gene profiles in multiple SCC cell lines to ES cell profiles and determined that SOX2 binds to distinct genomic loci in SCCs. In SCCs, SOX2 preferentially interacts with the transcription factor p63, as opposed to the transcription factor OCT4, which is the preferred SOX2 binding partner in ES cells. SOX2 and p63 exhibited overlapping genomic occupancy at a large number of loci in SCCs; however, coordinate binding of SOX2 and p63 was absent in ES cells. We further demonstrated that SOX2 and p63 jointly regulate gene expression, including the oncogeneETV4 , which was essential forSOX2 -amplified SCC cell survival. Together, these findings demonstrate that the action of SOX2 in SCC differs substantially from its role in pluripotency. The identification of the SCC-associated interaction between SOX2 and p63 will enable deeper characterization the downstream targets of this interaction in SCC and normal squamous epithelial physiology.Authors
Hideo Watanabe, Qiuping Ma, Shouyong Peng, Guillaume Adelmant, Danielle Swain, Wenyu Song, Cameron Fox, Joshua M. Francis, Chandra Sekhar Pedamallu, David S. DeLuca, Angela N. Brooks, Su Wang, Jianwen Que, Anil K. Rustgi, Kwok-kin Wong, Keith L. Ligon, X. Shirley Liu, Jarrod A. Marto, Matthew Meyerson, Adam J. Bass
×Abstract
Bone metastasis is a frequent complication of breast cancer that is often accelerated by TGF-β signaling; however, little is known about how the TGF-β pathway is regulated during bone metastasis. Here we report that deleted in liver cancer 1 (DLC1) is an important regulator of TGF-β responses and osteolytic metastasis of breast cancer cells. In murine models, breast cancer cells lacking DLC1 expression exhibited enhanced capabilities of bone metastasis. Knockdown of DLC1 in cancer cells promoted bone metastasis, leading to manifested osteolysis and accelerated death in mice, while DLC1 overexpression suppressed bone metastasis. Activation of Rho-ROCK signaling in the absence of DLC1 mediated SMAD3 linker region phosphorylation and TGF-β–induced expression of parathyroid hormone–like hormone (PTHLH), leading to osteoclast maturation for osteolytic colonization. Furthermore, pharmacological inhibition of Rho-ROCK effectively reduced PTHLH production and breast cancer bone metastasis in vitro and in vivo. Evaluation of clinical breast tumor samples revealed that reduced
DLC1 expression was linked to elevatedPTHLH expression and organ-specific metastasis to bone. Overall, our findings define a stroma-dependent paradigm of Rho signaling in cancer and implicate Rho–TGF-β crosstalk in osteolytic bone metastasis.Authors
Yufeng Wang, Rong Lei, Xueqian Zhuang, Ning Zhang, Hong Pan, Gang Li, Jing Hu, Xiaoqi Pan, Qian Tao, Da Fu, Jianru Xiao, Y. Eugene Chin, Yibin Kang, Qifeng Yang, Guohong Hu
×Abstract
Cleft lip, which results from impaired facial process growth and fusion, is one of the most common craniofacial birth defects. Many genes are known to be involved in the etiology of this disorder; however, our understanding of cleft lip pathogenesis remains incomplete. In the present study, we uncovered a role for sonic hedgehog (SHH) signaling during lip fusion. Mice carrying compound mutations in hedgehog acyltransferase (
Hhat ) and patched1 (Ptch1 ) exhibited perturbations in the SHH gradient during frontonasal development, which led to hypoplastic nasal process outgrowth, epithelial seam persistence, and cleft lip. Further investigation revealed that enhanced SHH signaling restricts canonical WNT signaling in the lambdoidal region by promoting expression of genes encoding WNT inhibitors. Moreover, reduction of canonical WNT signaling perturbed p63/interferon regulatory factor 6 (p63/IRF6) signaling, resulting in increased proliferation and decreased cell death, which was followed by persistence of the epithelial seam and cleft lip. Consistent with our results, mutations in genes that disrupt SHH and WNT signaling have been identified in both mice and humans with cleft lip. Collectively, our data illustrate that altered SHH signaling contributes to the etiology and pathogenesis of cleft lip through antagonistic interactions with other gene regulatory networks, including the canonical WNT and p63/IRF6 signaling pathways.Authors
Hiroshi Kurosaka, Angelo Iulianella, Trevor Williams, Paul A. Trainor
×Abstract
The G1 kinase CDK4 is amplified or overexpressed in some human tumors and promotes tumorigenesis by inhibiting known tumor suppressors. Here, we report that CDK4 deficiency markedly accelerated lymphoma development in the Eμ-
Myc transgenic mouse model of B lymphoma and that silencing or loss of CDK4 augmented the tumorigenic potential ofMyc -driven mouse and human B cell lymphoma in transplant models. Accelerated disease in CDK4-deficient Eμ-Myc transgenic mice was associated with rampant genomic instability that was provoked by dysregulation of a FOXO1/RAG1/RAG2 pathway. Specifically, CDK4 phosphorylated and inactivated FOXO1, which prevented FOXO1-dependent induction ofRag1 andRag2 transcription. CDK4-deficient Eμ-Myc B cells had high levels of the active form of FOXO1 and elevated RAG1 and RAG2. Furthermore, overexpression of RAG1 and RAG2 accelerated lymphoma development in a transplant model, with RAG1/2-expressing tumors exhibiting hallmarks of genomic instability. Evaluation of human tumor samples revealed that CDK4 expression was markedly suppressed, while FOXO1 expression was elevated, in several subtypes of human non-Hodgkin B cell lymphoma. Collectively, these findings establish a context-specific tumor suppressor function for CDK4 that prevents genomic instability, which contributes to B cell lymphoma. Furthermore, our data suggest that targeting CDK4 may increase the risk for the development and/or progression of lymphoma.Authors
Yuanzhi Lu, Yongsheng Wu, Xiaoling Feng, Rulong Shen, Jing H. Wang, Mohammad Fallahi, Weimin Li, Chunying Yang, William Hankey, Weiqiang Zhao, Ramesh K. Ganju, Ming O. Li, John L. Cleveland, Xianghong Zou
×Abstract
Terminal maturation of invariant NKT (iNKT) cells from stage 2 (CD44+NK1.1–) to stage 3 (CD44+NK1.1+) is accompanied by a functional acquisition of a predominant IFN-γ–producing (iNKT-1) phenotype; however, some cells develop into IL-17–producing iNKT (iNKT-17) cells. iNKT-17 cells are rare and restricted to a CD44+NK1.1– lineage. It is unclear how iNKT terminal maturation is regulated and what factors mediate the predominance of iNKT-1 compared with iNKT-17. The tumor suppressor tuberous sclerosis 1 (TSC1) is an important negative regulator of mTOR signaling, which regulates T cell differentiation, function, and trafficking. Here, we determined that mice lacking TSC1 exhibit a developmental block of iNKT differentiation at stage 2 and skew from a predominantly iNKT-1 population toward a predominantly iNKT-17 population, leading to enhanced airway hypersensitivity. Evaluation of purified iNKT cells revealed that TSC1 promotes T-bet, which regulates iNKT maturation, but downregulates ICOS expression in iNKT cells by inhibiting mTOR complex 1 (mTORC1). Furthermore, mice lacking T-bet exhibited both a terminal maturation defect of iNKT cells and a predominance of iNKT-17 cells, and increased ICOS expression was required for the predominance of iNKT-17 cells in the population of TSC1-deficient iNKT cells. Our data indicate that TSC1-dependent control of mTORC1 is crucial for terminal iNKT maturation and effector lineage decisions, resulting in the predominance of iNKT-1 cells.
Authors
Jinhong Wu, Jialong Yang, Kai Yang, Hongxia Wang, Balachandra Gorentla, Jinwook Shin, Yurong Qiu, Loretta G. Que, W. Michael Foster, Zhenwei Xia, Hongbo Chi, Xiao-Ping Zhong
×Abstract
Genetic studies have identified common variants within the intergenic region (
HBS1L-MYB ) between GTP-binding elongation factorHBS1L and myeloblastosis oncogeneMYB on chromosome 6q that are associated with elevated fetal hemoglobin (HbF) levels and alterations of other clinically important human erythroid traits. It is unclear how these noncoding sequence variants affect multiple erythrocyte characteristics. Here, we determined that severalHBS1L-MYB intergenic variants affect regulatory elements that are occupied by key erythroid transcription factors within this region. These elements interact withMYB , a critical regulator of erythroid development and HbF levels. We found that severalHBS1L-MYB intergenic variants reduce transcription factor binding, affecting long-range interactions withMYB andMYB expression levels. These data provide a functional explanation for the genetic association ofHBS1L-MYB intergenic polymorphisms with human erythroid traits and HbF levels. Our results further designateMYB as a target for therapeutic induction of HbF to ameliorate sickle cell and β-thalassemia disease severity.Authors
Ralph Stadhouders, Suleyman Aktuna, Supat Thongjuea, Ali Aghajanirefah, Farzin Pourfarzad, Wilfred van IJcken, Boris Lenhard, Helen Rooks, Steve Best, Stephan Menzel, Frank Grosveld, Swee Lay Thein, Eric Soler
×Abstract
Nitric oxide (NO) production is critical for the host defense against intracellular pathogens; however, it is unclear whether NO-dependent control of intracellular organisms depends on cell-intrinsic or cell-extrinsic activity of NO. For example, NO production by infected phagocytes may enable these cells to individually control their pathogen burden. Alternatively, the ability of NO to diffuse across cell membranes might be critical for infection control. Here, using a murine ear infection model, we found that, during infection with the intracellular parasite
Leishmania major , expression of inducible NO synthase does not confer a cell-intrinsic ability to lower parasite content. We demonstrated that the diffusion of NO promotes equally effective parasite killing in NO-producing and bystander cells. Importantly, the collective production of NO by numerous phagocytes was necessary to reach an effective antimicrobial activity. We propose that, in contrast to a cell-autonomous mode of pathogen control, this cooperative mechanism generates an antimicrobial milieu that provides the basis for pathogen containment at the tissue level.Authors
Romain Olekhnovitch, Bernhard Ryffel, Andreas J. Müller, Philippe Bousso
×Abstract
T cell depletion is commonly used in organ transplantation for immunosuppression; however, a restoration of T cell homeostasis following depletion leads to increased memory T cells, which may promote transplant rejection. The cytokine IL-7 is important for controlling lymphopoiesis under both normal and lymphopenic conditions. Here, we investigated whether blocking IL-7 signaling with a mAb that targets IL-7 receptor α (IL-7Rα) alone or following T cell depletion confers an advantage for allograft survival in murine transplant models. We found that IL-7R blockade alone induced indefinite pancreatic islet allograft survival if anti–IL-7R treatment was started 3 weeks before graft. IL-7R blockade following anti-CD4– and anti-CD8–mediated T cell depletion markedly prolonged skin allograft survival. Furthermore, IL-7 inhibition in combination with T cell depletion synergized with either CTLA-4Ig administration or suboptimal doses of tacrolimus to induce long-term skin graft acceptance in this stringent transplant model. Together, these therapies inhibited T cell reconstitution, decreased memory T cell numbers, increased the relative frequency of Tregs, and abrogated both cellular and humoral alloimmune responses. Our data suggest that IL-7R blockade following T cell depletion has potential as a robust, immunosuppressive therapy in transplantation.
Authors
Hoa-Le Mai, Françoise Boeffard, Julie Longis, Richard Danger, Bernard Martinet, Fabienne Haspot, Bernard Vanhove, Sophie Brouard, Jean-Paul Soulillou
×Abstract
Protein temporal dynamics play a critical role in time-dimensional pathophysiological processes, including the gradual cardiac remodeling that occurs in early-stage heart failure. Methods for quantitative assessments of protein kinetics are lacking, and despite knowledge gained from single-protein studies, integrative views of the coordinated behavior of multiple proteins in cardiac remodeling are scarce. Here, we developed a workflow that integrates deuterium oxide (2H2O) labeling, high-resolution mass spectrometry (MS), and custom computational methods to systematically interrogate in vivo protein turnover. Using this workflow, we characterized the in vivo turnover kinetics of 2,964 proteins in a mouse model of β-adrenergic–induced cardiac remodeling. The data provided a quantitative and longitudinal view of cardiac remodeling at the molecular level, revealing widespread kinetic regulations in calcium signaling, metabolism, proteostasis, and mitochondrial dynamics. We translated the workflow to human studies, creating a reference dataset of 496 plasma protein turnover rates from 4 healthy adults. The approach is applicable to short, minimal label enrichment and can be performed on as little as a single biopsy, thereby overcoming critical obstacles to clinical investigations. The protein turnover quantitation experiments and computational workflow described here should be widely applicable to large-scale biomolecular investigations of human disease mechanisms with a temporal perspective.
Authors
Maggie P.Y. Lam, Ding Wang, Edward Lau, David A. Liem, Allen K. Kim, Dominic C.M. Ng, Xiangbo Liang, Brian J. Bleakley, Chenguang Liu, Jason D. Tabaraki, Martin Cadeiras, Yibin Wang, Mario C. Deng, Peipei Ping
×Abstract
Peripheral nerve injuries and neuropathies lead to profound functional deficits. Here, we have demonstrated that muscle-derived stem/progenitor cells (MDSPCs) isolated from adult human skeletal muscle (hMDSPCs) can adopt neuronal and glial phenotypes in vitro and ameliorate a critical-sized sciatic nerve injury and its associated defects in a murine model. Transplanted hMDSPCs surrounded the axonal growth cone, while hMDSPCs infiltrating the regenerating nerve differentiated into myelinating Schwann cells. Engraftment of hMDSPCs into the area of the damaged nerve promoted axonal regeneration, which led to functional recovery as measured by sustained gait improvement. Furthermore, no adverse effects were observed in these animals up to 18 months after transplantation. Following hMDSPC therapy, gastrocnemius muscles from mice exhibited substantially less muscle atrophy, an increase in muscle mass after denervation, and reorganization of motor endplates at the postsynaptic sites compared with those from PBS-treated mice. Evaluation of nerve defects in animals transplanted with vehicle-only or myoblast-like cells did not reveal histological or functional recovery. These data demonstrate the efficacy of hMDSPC-based therapy for peripheral nerve injury and suggest that hMDSPC transplantation has potential to be translated for use in human neuropathies.
Authors
Mitra Lavasani, Seth D. Thompson, Jonathan B. Pollett, Arvydas Usas, Aiping Lu, Donna B. Stolz, Katherine A. Clark, Bin Sun, Bruno Péault, Johnny Huard
×Abstract
Injury to the specialized epithelial cells of the glomerulus (podocytes) underlies the pathogenesis of all forms of proteinuric kidney disease; however, the specific genetic changes that mediate podocyte dysfunction after injury are not fully understood. Here, we performed a large-scale insertional mutagenic screen of injury-resistant podocytes isolated from mice and found that increased expression of the gene
Rap1gap , encoding a RAP1 activation inhibitor, ameliorated podocyte injury resistance. Furthermore, injured podocytes in murine models of disease and kidney biopsies from glomerulosclerosis patients exhibited increased RAP1GAP, resulting in diminished glomerular RAP1 activation. In mouse models, podocyte-specific inactivation ofRap1a andRap1b induced massive glomerulosclerosis and premature death. Podocyte-specificRap1a andRap1b haploinsufficiency also resulted in severe podocyte damage, including features of podocyte detachment. Over-expression of RAP1GAP in cultured podocytes induced loss of activated β1 integrin, which was similarly observed in kidney biopsies from patients. Furthermore, preventing elevation of RAP1GAP levels in injured podocytes maintained β1 integrin–mediated adhesion and prevented cellular detachment. Taken together, our findings suggest that increased podocyte expression of RAP1GAP contributes directly to podocyte dysfunction by a mechanism that involves loss of RAP1-mediated activation of β1 integrin.Authors
Uma Potla, Jie Ni, Justin Vadaparampil, Guozhe Yang, Jeremy S. Leventhal, Kirk N. Campbell, Peter Y. Chuang, Alexei Morozov, John C. He, Vivette D. D’Agati, Paul E. Klotman, Lewis Kaufman
×Abstract
Background . Enhanced sympathetic activity at the ventricular myocardium can destabilize repolarization, increasing the risk of death. Sympathetic activity is known to cluster in low-frequency bursts; therefore, we hypothesized that sympathetic activity induces periodic low-frequency changes of repolarization. We developed a technique to assess the sympathetic effect on repolarization and identified periodic components in the low-frequency spectral range (≤0.1 Hz), which we termed periodic repolarization dynamics (PRD).Methods . We investigated the physiological properties of PRD in multiple experimental studies, including a swine model of steady-state ventilation (n = 7) and human studies involving fixed atrial pacing (n = 10), passive head-up tilt testing (n = 11), low-intensity exercise testing (n = 11), and beta blockade (n = 10). We tested the prognostic power of PRD in 908 survivors of acute myocardial infarction (MI). Finally, we tested the predictive values of PRD and T-wave alternans (TWA) in 2,965 patients undergoing clinically indicated exercise testing.Results . PRD was not related to underlying respiratory activity (P < 0.001) or heart-rate variability (P = 0.002). Furthermore, PRD was enhanced by activation of the sympathetic nervous system, and pharmacological blockade of sympathetic nervous system activity suppressed PRD (P ≤ 0.005 for both). Increased PRD was the strongest single risk predictor of 5-year total mortality (hazard ratio 4.75, 95% CI 2.94–7.66;P < 0.001) after acute MI. In patients undergoing exercise testing, the predictive value of PRD was strong and complementary to that of TWA.Conclusion . We have described and identified low-frequency rhythmic modulations of repolarization that are associated with sympathetic activity. Increased PRD can be used as a predictor of mortality in survivors of acute MI and patients undergoing exercise testing.Trial registration . ClinicalTrials.gov NCT00196274.Funding . This study was funded by Angewandte Klinische Forschung, University of Tübingen (252-1-0).Authors
Konstantinos D. Rizas, Tuomo Nieminen, Petra Barthel, Christine S. Zürn, Mika Kähönen, Jari Viik, Terho Lehtimäki, Kjell Nikus, Christian Eick, Tim O. Greiner, Hans P. Wendel, Peter Seizer, Jürgen Schreieck, Meinrad Gawaz, Georg Schmidt, Axel Bauer
×Abstract
Insulin signaling in osteoblasts has been shown recently to contribute to whole-body glucose homeostasis in animals fed a normal diet; however, it is unknown whether bone contributes to the insulin resistance that develops in animals challenged by a high-fat diet (HFD). Here, we evaluated the consequences of osteoblast-specific overexpression of or loss of insulin receptor in HFD-fed mice. We determined that the severity of glucose intolerance and insulin resistance that mice develop when fed a HFD is in part a consequence of osteoblast-dependent insulin resistance. Insulin resistance in osteoblasts led to a decrease in circulating levels of the active form of osteocalcin, thereby decreasing insulin sensitivity in skeletal muscle. Insulin resistance developed in osteoblasts as the result of increased levels of free saturated fatty acids, which promote insulin receptor ubiquitination and subsequent degradation. Together, these results underscore the involvement of bone, among other tissues, in the disruption of whole-body glucose homeostasis resulting from a HFD and the involvement of insulin and osteocalcin cross-talk in glucose intolerance. Furthermore, our data indicate that insulin resistance develops in bone as the result of lipotoxicity-associated loss of insulin receptors.
Authors
Jianwen Wei, Mathieu Ferron, Christopher J. Clarke, Yusuf A. Hannun, Hongfeng Jiang, William S. Blaner, Gerard Karsenty
×Abstract
The genes encoding RAS family members are frequently mutated in juvenile myelomonocytic leukemia (JMML) and acute myeloid leukemia (AML). RAS proteins are difficult to target pharmacologically; therefore, targeting the downstream PI3K and RAF/MEK/ERK pathways represents a promising approach to treat RAS-addicted tumors. The p110α isoform of PI3K (encoded by
Pik3ca ) is an essential effector of oncogenic KRAS in murine lung tumors, but it is unknown whether p110α contributes to leukemia. To specifically examine the role of p110α in murine hematopoiesis and in leukemia, we conditionally deleted p110α in HSCs using theCre-loxP system. Postnatal deletion of p110α resulted in mild anemia without affecting HSC self-renewal; however, deletion of p110α in mice with KRASG12D-associated JMML markedly delayed their death. Furthermore, the p110α-selective inhibitor BYL719 inhibited growth factor–independent KRASG12D BM colony formation and sensitized cells to a low dose of the MEK inhibitor MEK162. Furthermore, combined inhibition of p110α and MEK effectively reduced proliferation of RAS-mutated AML cell lines and disease in an AML murine xenograft model. Together, our data indicate that RAS-mutated myeloid leukemias are dependent on the PI3K isoform p110α, and combined pharmacologic inhibition of p110α and MEK could be an effective therapeutic strategy for JMML and AML.Authors
Kira Gritsman, Haluk Yuzugullu, Thanh Von, Howard Yan, Linda Clayton, Christine Fritsch, Sauveur-Michel Maira, Gregory Hollingworth, Christine Choi, Tulasi Khandan, Mahnaz Paktinat, Rachel O. Okabe, Thomas M. Roberts, Jean J. Zhao
×Abstract
Alteration of the surface glycosylation pattern on malignant cells potentially affects tumor immunity by directly influencing interactions with glycan-binding proteins (lectins) on the surface of immunomodulatory cells. The sialic acid–binding Ig-like lectins Siglec-7 and -9 are MHC class I–independent inhibitory receptors on human NK cells that recognize sialic acid–containing carbohydrates. Here, we found that the presence of Siglec-9 defined a subset of cytotoxic NK cells with a mature phenotype and enhanced chemotactic potential. Interestingly, this Siglec-9+ NK cell population was reduced in the peripheral blood of cancer patients. Broad analysis of primary tumor samples revealed that ligands of Siglec-7 and -9 were expressed on human cancer cells of different histological types. Expression of Siglec-7 and -9 ligands was associated with susceptibility of NK cell–sensitive tumor cells and, unexpectedly, of presumably NK cell–resistant tumor cells to NK cell–mediated cytotoxicity. Together, these observations have direct implications for NK cell–based therapies and highlight the requirement to consider both MHC class I haplotype and tumor-specific glycosylation.
Authors
Camilla Jandus, Kayluz Frias Boligan, Obinna Chijioke, He Liu, Meike Dahlhaus, Thomas Démoulins, Christoph Schneider, Marc Wehrli, Robert E. Hunger, Gabriela M. Baerlocher, Hans-Uwe Simon, Pedro Romero, Christian Münz, Stephan von Gunten
×Abstract
The autosomal recessive neurodegenerative disease spinal muscular atrophy (SMA) results from low levels of survival motor neuron (SMN) protein; however, it is unclear how reduced SMN promotes SMA development. Here, we determined that ubiquitin-dependent pathways regulate neuromuscular pathology in SMA. Using mouse models of SMA, we observed widespread perturbations in ubiquitin homeostasis, including reduced levels of ubiquitin-like modifier activating enzyme 1 (UBA1). SMN physically interacted with UBA1 in neurons, and disruption of
Uba1 mRNA splicing was observed in the spinal cords of SMA mice exhibiting disease symptoms. Pharmacological or genetic suppression of UBA1 was sufficient to recapitulate an SMA-like neuromuscular pathology in zebrafish, suggesting that UBA1 directly contributes to disease pathogenesis. Dysregulation of UBA1 and subsequent ubiquitination pathways led to β-catenin accumulation, and pharmacological inhibition of β-catenin robustly ameliorated neuromuscular pathology in zebrafish,Drosophila , and mouse models of SMA. UBA1-associated disruption of β-catenin was restricted to the neuromuscular system in SMA mice; therefore, pharmacological inhibition of β-catenin in these animals failed to prevent systemic pathology in peripheral tissues and organs, indicating fundamental molecular differences between neuromuscular and systemic SMA pathology. Our data indicate that SMA-associated reduction of UBA1 contributes to neuromuscular pathogenesis through disruption of ubiquitin homeostasis and subsequent β-catenin signaling, highlighting ubiquitin homeostasis and β-catenin as potential therapeutic targets for SMA.Authors
Thomas M. Wishart, Chantal A. Mutsaers, Markus Riessland, Michell M. Reimer, Gillian Hunter, Marie L. Hannam, Samantha L. Eaton, Heidi R. Fuller, Sarah L. Roche, Eilidh Somers, Robert Morse, Philip J. Young, Douglas J. Lamont, Matthias Hammerschmidt, Anagha Joshi, Peter Hohenstein, Glenn E. Morris, Simon H. Parson, Paul A. Skehel, Thomas Becker, Iain M. Robinson, Catherina G. Becker, Brunhilde Wirth, Thomas H. Gillingwater
×Abstract
Broadly HIV-1–neutralizing antibodies (BnAbs) display one or more unusual traits, including a long
h eavy chainc omplementarity-d eterminingr egion3 (HCDR3), polyreactivity, and high levels of somatic mutations. These shared characteristics suggest that BnAb development might be limited by immune tolerance controls. It has been postulated that HIV-1–infected individuals with autoimmune disease and defective immune tolerance mechanisms may produce BnAbs more readily than those without autoimmune diseases. In this study, we identified an HIV-1–infected individual with SLE who exhibited controlled viral load (<5,000 copies/ml) in the absence of controlling HLA phenotypes and developed plasma HIV-1 neutralization breadth. We collected memory B cells from this individual and isolated a BnAb, CH98, that targets the CD4 binding site (CD4bs) of HIV-1 envelope glycoprotein 120 (gp120). CH98 bound to human antigens including dsDNA, which is specifically associated with SLE. Anti-dsDNA reactivity was also present in the patient’s plasma. CH98 had a mutation frequency of 25% and 15% nt somatic mutations in the heavy and light chain variable domains, respectively, a long HCDR3, and a deletion in the light chain CDR1. The occurrence of anti-dsDNA reactivity by a HIV-1 CD4bs BnAb in an individual with SLE raises the possibility that some BnAbs and SLE-associated autoantibodies arise from similar pools of B cells.Authors
Mattia Bonsignori, Kevin Wiehe, Sebastian K. Grimm, Rebecca Lynch, Guang Yang, Daniel M. Kozink, Florence Perrin, Abby J. Cooper, Kwan-Ki Hwang, Xi Chen, Mengfei Liu, Krisha McKee, Robert J. Parks, Joshua Eudailey, Minyue Wang, Megan Clowse, Lisa G. Criscione-Schreiber, M. Anthony Moody, Margaret E. Ackerman, Scott D. Boyd, Feng Gao, Garnett Kelsoe, Laurent Verkoczy, Georgia D. Tomaras, Hua-Xin Liao, Thomas B. Kepler, David C. Montefiori, John R. Mascola, Barton F. Haynes
×Abstract
Variants in
SCN10A , which encodes a voltage-gated sodium channel, are associated with alterations of cardiac conduction parameters and the cardiac rhythm disorder Brugada syndrome; however, it is unclear howSCN10A variants promote dysfunctional cardiac conduction. Here we showed by high-resolution 4C-seq analysis of theScn10a -Scn5a locus in murine heart tissue that a cardiac enhancer located inScn10a , encompassingSCN10A functional variant rs6801957, interacts with the promoter ofScn5a , a sodium channel–encoding gene that is critical for cardiac conduction. We observed thatSCN5A transcript levels were several orders of magnitude higher thanSCN10A transcript levels in both adult human and mouse heart tissue. Analysis of BAC transgenic mouse strains harboring an engineered deletion of the enhancer withinScn10a revealed that the enhancer was essential forScn5a expression in cardiac tissue. Furthermore, the commonSCN10A variant rs6801957 modulatedScn5a expression in the heart. In humans, theSCN10A variant rs6801957, which correlated with slowed conduction, was associated with reducedSCN5A expression. These observations establish a genomic mechanism for how a common genetic variation atSCN10A influences cardiac physiology and predisposes to arrhythmia.Authors
Malou van den Boogaard, Scott Smemo, Ozanna Burnicka-Turek, David E. Arnolds, Harmen J.G. van de Werken, Petra Klous, David McKean, Jochen D. Muehlschlegel, Julia Moosmann, Okan Toka, Xinan H. Yang, Tamara T. Koopmann, Michiel E. Adriaens, Connie R. Bezzina, Wouter de Laat, Christine Seidman, J.G. Seidman, Vincent M. Christoffels, Marcelo A. Nobrega, Phil Barnett, Ivan P. Moskowitz
×Abstract
Members of the miR-34 family are induced by the tumor suppressor p53 and are known to inhibit epithelial-to-mesenchymal transition (EMT) and therefore presumably suppress the early phases of metastasis. Here, we determined that exposure of human colorectal cancer (CRC) cells to the cytokine IL-6 activates the oncogenic STAT3 transcription factor, which directly represses the
MIR34A gene via a conserved STAT3-binding site in the first intron. Repression ofMIR34A was required for IL-6–induced EMT and invasion. Furthermore, we identified the IL-6 receptor (IL-6R), which mediates IL-6–dependent STAT3 activation, as a conserved, direct miR-34a target. The resulting IL-6R/STAT3/miR-34a feedback loop was present in primary colorectal tumors as well as CRC, breast, and prostate cancer cell lines and associated with a mesenchymal phenotype. An active IL-6R/STAT3/miR-34a loop was necessary for EMT, invasion, and metastasis of CRC cell lines and was associated with nodal and distant metastasis in CRC patient samples. p53 activation in CRC cells interfered with IL-6–induced invasion and migration via miR-34a–dependent downregulation ofIL6R expression. InMir34a -deficient mice, colitis-associated intestinal tumors displayed upregulation of p-STAT3, IL-6R, and SNAIL and progressed to invasive carcinomas, which was not observed in WT animals. Collectively, our data indicate that p53-dependent expression of miR-34a suppresses tumor progression by inhibiting a IL-6R/STAT3/miR-34a feedback loop.Authors
Matjaz Rokavec, Meryem Gülfem Öner, Huihui Li, Rene Jackstadt, Longchang Jiang, Dmitri Lodygin, Markus Kaller, David Horst, Paul K. Ziegler, Sarah Schwitalla, Julia Slotta-Huspenina, Franz G. Bader, Florian R. Greten, Heiko Hermeking
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ISSN: 0021-9738 (print), 1558-8238 (online)