Issue published December 1, 2014 Previous issue | Next issue
- Volume 124, Issue 12
Go to section:
On the cover: JC virus infection targets astrocytes
-
Commentaries
×
Abstract
Restenosis after balloon angioplasty and stenting (BAS) remains an unsolved clinical dilemma for patients with coronary artery disease. A better understanding of the mechanisms that drive this phenomenon is likely to lead to more effective treatments. In this issue of the
JCI , Ali et al. uncover a critical redox axis with the antioxidant enzyme glutathione peroxidase-1 (GPX1) at its hub and identify potential new therapeutic targets, such as ROS1 tyrosine kinase. This study represents a potential new approach to finding a treatment for BAS, with implications that may extend beyond BAS to other vasculopathies involving vascular remodeling.Authors
Judy B. de Haan
×Abstract
Memory B cells are a dynamic subset of the mature B cell population that in some cases can reenter germinal centers (GCs) in response to iterative infections. Such a reactivation can lead to accumulation of genetic lesions in these cells, potentially from repetitive activation of the B cell mutator enzyme AID. Normal memory B cells do not survive repeated reentries into GCs. In this issue, Sungalee et al. demonstrate that memory B cells harboring the oncogenic
BCL2:IGH translocation, which results in constitutive BCL2 expression, survive multiple GC entries upon repetitive immunization. Through these multiple GC reentries, the hallmarkBCL2:IGH translocation enables AID-induced hypermutation and propagates clonal evolution toward malignant follicular lymphoma.Authors
Srividya Swaminathan, Markus Müschen
×Abstract
The liver is capable of full regeneration following several types and rounds of injury, ranging from hepatectomy to toxin-mediated damage. The source of this regenerative capacity has long been a hotly debated topic. The damage response that occurs when hepatocyte proliferation is impaired is thought to be mediated by oval/dedifferentiated progenitor cells, which replenish the hepatocyte and ductal compartments of the liver. Recently, reports have questioned whether these oval/progenitor cells truly serve as the facultative stem cell of the liver following toxin-mediated damage. In this issue of the
JCI , Kordes and colleagues use lineage tracing to follow transplanted rat hepatic stellate cells, a resident liver mesenchymal cell population, in hosts that have suffered liver damage. Transplanted stellate cells repopulated the damaged rat liver by contributing to the oval cell response. These data establish yet another cell type of mesenchymal origin as the progenitor for the oval/ductular response in the rat. The lack of uniformity between different damage models, the extent of the injury to the liver parenchyma, and potential species-specific differences might be at the core of the discrepancy between different studies. Taken together, these data imply a considerable degree of plasticity in the liver, whereby several cell types can contribute to regeneration.Authors
Christopher J. Hindley, Gianmarco Mastrogiovanni, Meritxell Huch
×Abstract
JC virus (JCV) causes progressive multifocal leukoencephalopathy (PML), a demyelinating disease in humans. The disease, once considered fatal, is now managed with immune reconstitution therapy; however, surviving patients remain severely debilitated. Until now, there has been no animal model to study JCV in the brain, and research into treatment has relied on cell culture systems. In this issue of the
JCI , Kondo and colleagues developed a mouse model in which human glial cells are engrafted into neonatal mice that are both immunodeficient and deficient for myelin basic protein. When challenged intracerebrally with JCV, these mice exhibit some of the characteristics of PML. The establishment of this chimeric mouse model is a significant advance toward understanding the mechanism of JCV pathogenesis and the identification of drugs to treat or prevent the disease.Authors
Sheila A. Haley, Walter J. Atwood
×Abstract
An emerging view is that breast cancer is a systemic disease that utilizes intrinsic and extrinsic tumor cell processes to support both primary tumor growth and metastatic dissemination into distal tissue. Delineation of factors involved in these processes should facilitate a better understanding for both assessing and preventing disease relapse. In this issue of the
JCI , Le et al. investigate whether intrinsic properties of metastatic breast cancer cell growth can be regulated through an extrinsic process — contact with tumor cell–derived extracellular vesicles containing microRNAs of the miR-200 family. The authors provide compelling evidence that miR-200s within extracellular vesicles secreted from highly metastatic tumor cells can be internalized by weakly metastatic cells. Thus, internalization and delivery of this metastatic “donor” cell–derived message provide plausible mechanisms by which oncogenic and regulatory factors confer the capability of tumor growth at metastatic lesions. This study provides a strong rationale for detailed assessment of the prognostic and predictive value of circulating extracellular vesicle–bound miR-200s in breast cancer progression and treatment.Authors
David M. Epstein
-
Research Articles
×
Abstract
Metastasis is associated with poor prognosis in breast cancer patients. Not all cancer cells within a tumor are capable of metastasizing. The microRNA-200 (miR-200) family, which regulates the mesenchymal-to-epithelial transition, is enriched in the serum of patients with metastatic cancers. Ectopic expression of miR-200 can confer metastatic ability to poorly metastatic tumor cells in some settings. Here, we investigated whether metastatic capability could be transferred between metastatic and nonmetastatic cancer cells via extracellular vesicles. miR-200 was secreted in extracellular vesicles from metastatic murine and human breast cancer cell lines, and miR-200 levels were increased in sera of mice bearing metastatic tumors. In culture, murine and human metastatic breast cancer cell extracellular vesicles transferred miR-200 microRNAs to nonmetastatic cells, altering gene expression and promoting mesenchymal-to-epithelial transition. In murine cancer and human xenograft models, miR-200–expressing tumors and extracellular vesicles from these tumors promoted metastasis of otherwise weakly metastatic cells either nearby or at distant sites and conferred to these cells the ability to colonize distant tissues in a miR-200–dependent manner. Together, our results demonstrate that metastatic capability can be transferred by the uptake of extracellular vesicles.
Authors
Minh T.N. Le, Peter Hamar, Changying Guo, Emre Basar, Ricardo Perdigão-Henriques, Leonora Balaj, Judy Lieberman
×Abstract
The most severe form of autosomal dominant polycystic kidney disease occurs in patients with mutations in the gene (
PKD1 ) encoding polycystin-1 (PC1). PC1 is a complex polytopic membrane protein expressed in cilia that undergoes autoproteolytic cleavage at a G protein–coupled receptor proteolytic site (GPS). A quarter of PKD1 mutations are missense variants, though it is not clear how these mutations promote disease. Here, we established a cell-based system to evaluate these mutations and determined that GPS cleavage is required for PC1 trafficking to cilia. A common feature among a subset of pathogenic missense mutations is a resulting failure of PC1 to traffic to cilia regardless of GPS cleavage. The application of our system also identified a missense mutation in the gene encoding polycystin-2 (PC2) that prevented this protein from properly trafficking to cilia. Using aPkd1 -BAC recombineering approach, we developed murine models to study the effects of these mutations and confirmed that only the cleaved form of PC1 exits the ER and can rescue the embryonically lethalPkd1 -null mutation. Additionally, steady-state expression levels of the intramembranous COOH-terminal fragment of cleaved PC1 required an intact interaction with PC2. The results of this study demonstrate that PC1 trafficking and expression require GPS cleavage and PC2 interaction, respectively, and provide a framework for functional assays to categorize the effects of missense mutations in polycystins.Authors
Yiqiang Cai, Sorin V. Fedeles, Ke Dong, Georgia Anyatonwu, Tamehito Onoe, Michihiro Mitobe, Jian-Dong Gao, Dayne Okuhara, Xin Tian, Anna-Rachel Gallagher, Zhangui Tang, Xiaoli Xie, Maria D. Lalioti, Ann-Hwee Lee, Barbara E. Ehrlich, Stefan Somlo
×Abstract
Patients with gastric and esophageal (GE) adenocarcinoma tumors in which the oncogene
ERBB2 has been amplified are routinely treated with a combination of cytotoxic chemotherapy and the ERBB2-directed antibody trastuzumab; however, the addition of trastuzumab, even when tested in a selected biomarker-positive patient population, provides only modest survival gains. To investigate the potential reasons for the modest impact of ERBB2-directed therapies, we explored the hypothesis that secondary molecular features ofERBB2 -amplified GE adenocarcinomas attenuate the impact of ERBB2 blockade. We analyzed genomic profiles ofERBB2 -amplified GE adenocarcinomas and determined that the majority ofERBB2 -amplified tumors harbor secondary oncogenic alterations that have the potential to be therapeutically targeted. These secondary events spanned genes involved in cell-cycle regulation as well as phosphatidylinositol-3 kinase and receptor tyrosine kinase signaling. UsingERBB2 -amplified cell lines, we demonstrated that secondary oncogenic events could confer resistance to ERBB2-directed therapies. Moreover, this resistance could be overcome by targeting the secondary oncogene in conjunction with ERBB2-directed therapy.EGFR is commonly coamplified withERBB2 , and in the setting ofERBB2 amplification, higher EGFR expression appears to mark tumors with greater sensitivity to dual EGFR/ERBB2 kinase inhibitors. These data suggest that combination inhibitor strategies, guided by secondary events inERBB2 -amplified GE adenocarcinomas, should be evaluated in clinical trials.Authors
Jihun Kim, Cameron Fox, Shouyong Peng, Mark Pusung, Eirini Pectasides, Eric Matthee, Yong Sang Hong, In-Gu Do, Jiryeon Jang, Aaron R. Thorner, Paul Van Hummelen, Anil K. Rustgi, Kwok-Kin Wong, Zhongren Zhou, Ping Tang, Kyoung-Mee Kim, Jeeyun Lee, Adam J. Bass
×Abstract
Angioplasty and stenting is the primary treatment for flow-limiting atherosclerosis; however, this strategy is limited by pathological vascular remodeling. Using a systems approach, we identified a role for the network hub gene glutathione peroxidase-1 (
GPX1 ) in pathological remodeling following human blood vessel stenting. Constitutive deletion ofGpx1 in atherosclerotic mice recapitulated this phenotype of increased vascular smooth muscle cell (VSMC) proliferation and plaque formation. In an independent patient cohort, gene variant pair analysis identified an interaction ofGPX1 with the orphan protooncogene receptor tyrosine kinaseROS1 . A meta-analysis of the only genome-wide association studies of human neointima-induced in-stent stenosis confirmed the association of theROS1 variant with pathological remodeling. Decreased GPX1 expression in atherosclerotic mice led to reductive stress via a time-dependent increase in glutathione, corresponding to phosphorylation of the ROS1 kinase activation site Y2274. Loss ofGPX1 function was associated with both oxidative and reductive stress, the latter driving ROS1 activity vias -glutathiolation of critical residues of the ROS1 tyrosine phosphatase SHP-2. ROS1 inhibition with crizotinib and deglutathiolation of SHP-2 abolished GPX1-mediated increases in VSMC proliferation while leaving endothelialization intact. Our results indicate that GPX1-dependent alterations in oxido-reductive stress promote ROS1 activation and mediate vascular remodeling.Authors
Ziad A. Ali, Vinicio de Jesus Perez, Ke Yuan, Mark Orcholski, Stephen Pan, Wei Qi, Gaurav Chopra, Christopher Adams, Yoko Kojima, Nicholas J. Leeper, Xiumei Qu, Kathia Zaleta-Rivera, Kimihiko Kato, Yoshiji Yamada, Mitsutoshi Oguri, Allan Kuchinsky, Stanley L. Hazen, J. Wouter Jukema, Santhi K. Ganesh, Elizabeth G. Nabel, Keith Channon, Martin B. Leon, Alain Charest, Thomas Quertermous, Euan A. Ashley
×Abstract
Nonalcoholic fatty liver disease (NAFLD) spectrum disorders affect approximately 1 billion individuals worldwide. However, the drivers of progressive steatohepatitis remain incompletely defined. Ketogenesis can dispose of much of the fat that enters the liver, and dysfunction in this pathway could promote the development of NAFLD. Here, we evaluated mice lacking mitochondrial 3-hydroxymethylglutaryl CoA synthase (HMGCS2) to determine the role of ketogenesis in preventing diet-induced steatohepatitis. Antisense oligonucleotide–induced loss of HMGCS2 in chow-fed adult mice caused mild hyperglycemia, increased hepatic gluconeogenesis from pyruvate, and augmented production of hundreds of hepatic metabolites, a suite of which indicated activation of the de novo lipogenesis pathway. High-fat diet feeding of mice with insufficient ketogenesis resulted in extensive hepatocyte injury and inflammation, decreased glycemia, deranged hepatic TCA cycle intermediate concentrations, and impaired hepatic gluconeogenesis due to sequestration of free coenzyme A (CoASH). Supplementation of the CoASH precursors pantothenic acid and cysteine normalized TCA intermediates and gluconeogenesis in the livers of ketogenesis-insufficient animals. Together, these findings indicate that ketogenesis is a critical regulator of hepatic acyl-CoA metabolism, glucose metabolism, and TCA cycle function in the absorptive state and suggest that ketogenesis may modulate fatty liver disease.
Authors
David G. Cotter, Baris Ercal, Xiaojing Huang, Jamison M. Leid, D. André d’Avignon, Mark J. Graham, Dennis J. Dietzen, Elizabeth M. Brunt, Gary J. Patti, Peter A. Crawford
×Abstract
Follicular Tregs (Tfr cells) inhibit antibody production, whereas follicular Th cells (Tfh cells) stimulate it. Tfr cells are found in blood; however, relatively little is known about the developmental signals for these cells or their functions. Here we demonstrated that circulating Tfr and Tfh cells share properties of memory cells and are distinct from effector Tfr and Tfh cells found within lymph nodes (LNs). Circulating memory-like Tfh cells were potently reactivated by DCs, homed to germinal centers, and produced more cytokines than did effector LN Tfh cells. Circulating memory-like Tfr cells persisted for long periods of time in vivo and homed to germinal centers after reactivation. Effector LN Tfr cells suppressed Tfh cell activation and production of cytokines, including IL-21, and inhibited class switch recombination and B cell activation. The suppressive function of this population was not dependent on specific antigen. Similar to LN effector Tfr cells, circulating Tfr cells also suppressed B and Tfh cells, but with a much lower capacity. Our data indicate that circulating memory-like Tfr cells are less suppressive than LN Tfr cells and circulating memory-like Tfh cells are more potent than LN effector Tfh cells; therefore, these circulating populations can provide rapid and robust systemic B cell help during secondary antigen exposure.
Authors
Peter T. Sage, David Alvarez, Jernej Godec, Ulrich H. von Andrian, Arlene H. Sharpe
×Abstract
Dermal infiltration of T cells is an important step in the onset and progression of immune-mediated skin diseases such as psoriasis; however, it is not known whether epidermal factors play a primary role in the development of these diseases. Here, we determined that the prodifferentiation transcription factor grainyhead-like 3 (GRHL3), which is essential during epidermal development, is dispensable for adult skin homeostasis, but required for barrier repair after adult epidermal injury. Consistent with activation of a GRHL3-regulated repair pathway in psoriasis, we found that GRHL3 is upregulated in lesional skin and binds known epidermal differentiation gene targets. Using an imiquimod-induced model of immune-mediated epidermal hyperplasia, we found that mice lacking GRHL3 have an exacerbated epidermal damage response, greater sensitivity to disease induction, delayed resolution of epidermal lesions, and resistance to anti–IL-22 therapy compared with WT animals. ChIP-Seq and gene expression profiling of murine skin revealed that while GRHL3 regulates differentiation pathways both during development and during repair from immune-mediated damage, it targets distinct sets of genes in the 2 processes. In particular, GRHL3 suppressed a number of alarmin and other proinflammatory genes after immune injury. This study identifies a GRHL3-regulated epidermal barrier repair pathway that suppresses disease initiation and helps resolve existing lesions in immune-mediated epidermal hyperplasia.
Authors
William M. Gordon, Michael D. Zeller, Rachel H. Klein, William R. Swindell, Hsiang Ho, Francisco Espetia, Johann E. Gudjonsson, Pierre F. Baldi, Bogi Andersen
×Abstract
Tooth enamel is the hardest substance in the human body and has a unique combination of hardness and fracture toughness that protects teeth from dental caries, the most common chronic disease worldwide. In addition to a high mineral content, tooth enamel comprises organic material that is important for mechanical performance and influences the initiation and progression of caries; however, the protein composition of tooth enamel has not been fully characterized. Here, we determined that epithelial hair keratins, which are crucial for maintaining the integrity of the sheaths that support the hair shaft, are expressed in the enamel organ and are essential organic components of mature enamel. Using genetic and intraoral examination data from 386 children and 706 adults, we found that individuals harboring known hair disorder–associated polymorphisms in the gene encoding keratin 75 (KRT75), KRT75A161T and KRT75E337K, are prone to increased dental caries. Analysis of teeth from individuals carrying the KRT75A161T variant revealed an altered enamel structure and a marked reduction of enamel hardness, suggesting that a functional keratin network is required for the mechanical stability of tooth enamel. Taken together, our results identify a genetic locus that influences enamel structure and establish a connection between hair disorders and susceptibility to dental caries.
Authors
Olivier Duverger, Takahiro Ohara, John R. Shaffer, Danielle Donahue, Patricia Zerfas, Andrew Dullnig, Christopher Crecelius, Elia Beniash, Mary L. Marazita, Maria I. Morasso
×Abstract
Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disorder with no effective medical treatments available. The generation of myofibroblasts, which are critical for fibrogenesis, requires both a mechanical signal and activated TGF-β; however, it is not clear how fibroblasts sense and transmit the mechanical signal(s) that promote differentiation into myofibroblasts. As transient receptor potential vanilloid 4 (TRPV4) channels are activated in response to changes in plasma membrane stretch/matrix stiffness, we investigated whether TRPV4 contributes to generation of myofibroblasts and/or experimental lung fibrosis. We determined that TRPV4 activity is upregulated in lung fibroblasts derived from patients with IPF. Moreover, TRPV4-deficient mice were protected from fibrosis. Furthermore, genetic ablation or pharmacological inhibition of TRPV4 function abrogated myofibroblast differentiation, which was restored by TRPV4 reintroduction. TRPV4 channel activity was elevated when cells were plated on matrices of increasing stiffness or on fibrotic lung tissue, and matrix stiffness–dependent myofibroblast differentiation was reduced in response to TRVP4 inhibition. TRPV4 activity modulated TGF-β1–dependent actions in a SMAD-independent manner, enhanced actomyosin remodeling, and increased nuclear translocation of the α-SMA transcription coactivator (MRTF-A). Together, these data indicate that TRPV4 activity mediates pulmonary fibrogenesis and suggest that manipulation of TRPV4 channel activity has potential as a therapeutic approach for fibrotic diseases.
Authors
Shaik O. Rahaman, Lisa M. Grove, Sailaja Paruchuri, Brian D. Southern, Susamma Abraham, Kathryn A. Niese, Rachel G. Scheraga, Sudakshina Ghosh, Charles K. Thodeti, David X. Zhang, Magdalene M. Moran, William P. Schilling, Daniel J. Tschumperlin, Mitchell A. Olman
×Abstract
Heterotrimers composed of B cell CLL/lymphoma 10 (BCL10), mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1), and caspase recruitment domain–containing (CARD) family adaptors play a role in NF-κB activation and have been shown to be involved in both the innate and the adaptive arms of immunity in murine models. Moreover, individuals with inherited defects of MALT1, CARD9, and CARD11 present with immunological and clinical phenotypes. Here, we characterized a case of autosomal-recessive, complete BCL10 deficiency in a child with a broad immunodeficiency, including defects of both hematopoietic and nonhematopoietic immunity. The patient died at 3 years of age and was homozygous for a loss-of-expression, loss-of-function
BCL10 mutation. The effect of BCL10 deficiency was dependent on the signaling pathway, and, for some pathways, the cell type affected. Despite the noted similarities to BCL10 deficiency in mice, including a deficient adaptive immune response, human BCL10 deficiency in this patient resulted in a number of specific features within cell populations. Treatment of the patient’s myeloid cells with a variety of pathogen-associated molecular pattern molecules (PAMPs) elicited a normal response; however, NF-κB–mediated fibroblast functions were dramatically impaired. The results of this study indicate that inherited BCL10 deficiency should be considered in patients with combined immunodeficiency with B cell, T cell, and fibroblast defects.Authors
Juan Manuel Torres, Rubén Martinez-Barricarte, Sonia García-Gómez, Marina S. Mazariegos, Yuval Itan, Bertrand Boisson, Rita Álvarez, Anaïs Jiménez-Reinoso, Lucia del Pino, Rebeca Rodríguez-Pena, Antonio Ferreira, Enrique Hernández-Jiménez, Victor Toledano, Carolina Cubillos-Zapata, Mariana Díaz-Almirón, Eduardo López-Collazo, José L. Unzueta-Roch, Silvia Sánchez-Ramón, Jose R. Regueiro, Eduardo López-Granados, Jean-Laurent Casanova, Rebeca Pérez de Diego
×Abstract
Autophagy allows cells to adapt to changes in their environment by coordinating the degradation and recycling of cellular components and organelles to maintain homeostasis. Lysosomes are organelles critical for terminating autophagy via their fusion with mature autophagosomes to generate autolysosomes that degrade autophagic materials; therefore, maintenance of the lysosomal population is essential for autophagy-dependent cellular clearance. Here, we have demonstrated that the two most common autosomal recessive hereditary spastic paraplegia gene products, the SPG15 protein spastizin and the SPG11 protein spatacsin, are pivotal for autophagic lysosome reformation (ALR), a pathway that generates new lysosomes. Lysosomal targeting of spastizin required an intact FYVE domain, which binds phosphatidylinositol 3-phosphate. Loss of spastizin or spatacsin resulted in depletion of free lysosomes, which are competent to fuse with autophagosomes, and an accumulation of autolysosomes, reflecting a failure in ALR. Moreover, spastizin and spatacsin were essential components for the initiation of lysosomal tubulation. Together, these results link dysfunction of the autophagy/lysosomal biogenesis machinery to neurodegeneration.
Authors
Jaerak Chang, Seongju Lee, Craig Blackstone
×Abstract
Multiple myeloma (MM) is a plasma cell neoplasm that results from clonal expansion of an Ig-secreting terminally differentiated B cell. Advanced MM is characterized by tissue damage that involves bone, kidney, and other organs and is typically associated with recurrent genetic abnormalities. IL-6 signaling via the IL-6 signal transducer GP130 has been implicated as an important driver of MM pathogenesis. Here, we demonstrated that ectopic expression of constitutively active GP130 (L-GP130) in a murine retroviral transduction-transplantation model induces rapid MM development of high penetrance. L-GP130–expressing mice recapitulated all of the characteristics of human disease, including monoclonal gammopathy, BM infiltration with lytic bone lesions, and protein deposition in the kidney. Moreover, the disease was easily transplantable and allowed different therapeutic options to be evaluated in vitro and in vivo. Using this model, we determined that GP130 signaling collaborated with MYC to induce MM and was responsible and sufficient for directing the plasma cell phenotype. Accordingly, we identified
Myc aberrations in the L-GP130 MM model. Evaluation of human MM samples revealed recurrent activation of STAT3, a downstream target of GP130 signaling. Together, our results indicate that deregulated GP130 activity contributes to MM pathogenesis and that pathways downstream of GP130 activity have potential as therapeutic targets in MM.Authors
Tobias Dechow, Sabine Steidle, Katharina S. Götze, Martina Rudelius, Kerstin Behnke, Konstanze Pechloff, Susanne Kratzat, Lars Bullinger, Falko Fend, Valeria Soberon, Nadya Mitova, Zhoulei Li, Markus Thaler, Jan Bauer, Elke Pietschmann, Corinna Albers, Rebekka Grundler, Marc Schmidt-Supprian, Jürgen Ruland, Christian Peschel, Justus Duyster, Stefan Rose-John, Florian Bassermann, Ulrich Keller
×Abstract
Chromosomal translocation that results in fusion of the genes encoding RNA-binding protein EWS and transcription factor FLI1 (EWS-FLI1) is pathognomonic for Ewing sarcoma. EWS-FLI1 alters gene expression through mechanisms that are not completely understood. We performed RNA sequencing (RNAseq) analysis on primary pediatric human mesenchymal progenitor cells (pMPCs) expressing EWS-FLI1 in order to identify gene targets of this oncoprotein. We determined that long noncoding RNA-277 (Ewing sarcoma–associated transcript 1 [
EWSAT1 ]) is upregulated by EWS-FLI1 in pMPCs. Inhibition ofEWSAT1 expression diminished the ability of Ewing sarcoma cell lines to proliferate and form colonies in soft agar, whereasEWSAT1 inhibition had no effect on other cell types tested. Expression of EWS-FLI1 andEWSAT1 repressed gene expression, and a substantial fraction of targets that were repressed by EWS-FLI1 were also repressed byEWSAT1 . Analysis of RNAseq data from primary human Ewing sarcoma further supported a role forEWSAT1 in mediating gene repression. We identified heterogeneous nuclear ribonucleoprotein (HNRNPK) as an RNA-binding protein that interacts withEWSAT1 and found a marked overlap in HNRNPK-repressed genes and those repressed by EWS-FLI1 andEWSAT1 , suggesting that HNRNPK participates inEWSAT1 -mediated gene repression. Together, our data reveal thatEWSAT1 is a downstream target of EWS-FLI1 that facilitates the development of Ewing sarcoma via the repression of target genes.Authors
Michelle Marques Howarth, David Simpson, Siu P. Ngok, Bethsaida Nieves, Ron Chen, Zurab Siprashvili, Dedeepya Vaka, Marcus R. Breese, Brian D. Crompton, Gabriela Alexe, Doug S. Hawkins, Damon Jacobson, Alayne L. Brunner, Robert West, Jaume Mora, Kimberly Stegmaier, Paul Khavari, E. Alejandro Sweet-Cordero
×Abstract
Patients with triple-negative breast cancer (TNBC) have a high incidence of early relapse and metastasis; however, the molecular basis for recurrence in these individuals remains poorly understood. Here, we demonstrate that
RASAL2 , which encodes a RAS-GTPase–activating protein (RAS-GAP), is a functional target of anti-invasive microRNA-203 and is overexpressed in a subset of triple-negative or estrogen receptor–negative (ER-negative) breast tumors. As opposed to luminal B ER-positive breast cancers, in which RASAL2 has been shown to act as a RAS-GAP tumor suppressor, we found that RASAL2 is oncogenic in TNBC and drives mesenchymal invasion and metastasis. Moreover, high RASAL2 expression was predictive of poor disease outcomes in patients with TNBC. RASAL2 acted independently of its RAS-GAP catalytic activity in TNBC; however, RASAL2 promoted small GTPase RAC1 signaling, which promotes mesenchymal invasion, through binding and antagonizing the RAC1-GAP protein ARHGAP24. Together, these results indicate that activation of a RASAL2/ARHGAP24/RAC1 module contributes to TNBC tumorigenesis and identify a context-dependent role ofRASAL2 in breast cancer.Authors
Min Feng, Yi Bao, Zhimei Li, Juntao Li, Min Gong, Stella Lam, Jinhua Wang, Diego M. Marzese, Nicholas Donovan, Ern Yu Tan, Dave S.B. Hoon, Qiang Yu
×Abstract
Human cytomegalovirus (HCMV) infection is the most common cause of congenital viral infections and a major source of morbidity and mortality after organ transplantation. NK cells are pivotal effector cells in the innate defense against CMV. Recently, hallmarks of adaptive responses, such as memory-like features, have been recognized in NK cells. HCMV infection elicits the expansion of an NK cell subset carrying an activating receptor heterodimer, comprising CD94 and NKG2C (CD94/NKG2C), a response that resembles the clonal expansion of adaptive immune cells. Here, we determined that expansion of this NKG2C+ subset and general NK cell recovery rely on signals derived from CD14+ monocytes. In a coculture system, a subset of CD14+ cells with inflammatory monocyte features produced IL-12 in response to HCMV-infected fibroblasts, and neutralization of IL-12 in this model substantially reduced CD25 upregulation and NKG2C+ subset expansion. Finally, blockade of CD94/NKG2C on NK cells or silencing of the cognate ligand HLA-E in infected fibroblasts greatly impaired expansion of NKG2C+ NK cells. Together, our results reveal that IL-12, CD14+ cells, and the CD94/NKG2C/HLA-E axis are critical for the expansion of NKG2C+ NK cells in response to HCMV infection. Moreover, strategies targeting the NKG2C+ NK cell subset have the potential to be exploited in NK cell–based intervention strategies against viral infections and cancer.
Authors
Alexander Rölle, Julia Pollmann, Eva-Maria Ewen, Vu Thuy Khanh Le, Anne Halenius, Hartmut Hengel, Adelheid Cerwenka
×Abstract
Genome-wide association studies have identified a link between genetic variation at the human chromosomal locus 1p13.3 and coronary artery disease. The gene encoding sortilin (
SORT1 ) has been implicated as the causative gene within the locus, as sortilin regulates hepatic lipoprotein metabolism. Here we demonstrated that sortilin also directly affects atherogenesis, independent of its regulatory role in lipoprotein metabolism. In a mouse model of atherosclerosis, deletion ofSort1 did not alter plasma cholesterol levels, but reduced the development of both early and late atherosclerotic lesions. We determined that sortilin is a high-affinity receptor for the proinflammatory cytokines IL-6 and IFN-γ. Moreover, macrophages and Th1 cells (both of which mediate atherosclerotic plaque formation) lacking sortilin had reduced secretion of IL-6 and IFN-γ, but not of other measured cytokines. Transfer of sortilin-deficient BM into irradiated atherosclerotic mice reduced atherosclerosis and systemic markers of inflammation. Together, these data demonstrate that sortilin influences cytokine secretion and that targeting sortilin in immune cells attenuates inflammation and reduces atherosclerosis.Authors
Martin B. Mortensen, Mads Kjolby, Stine Gunnersen, Jakob V. Larsen, Johan Palmfeldt, Erling Falk, Anders Nykjaer, Jacob F. Bentzon
×Abstract
Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease triggered by infection with the human gliotropic JC virus (JCV). Due to the human-selective nature of the virus, there are no animal models available to investigate JCV pathogenesis. To address this issue, we developed mice with humanized white matter by engrafting human glial progenitor cells (GPCs) into neonatal immunodeficient and myelin-deficient mice. Intracerebral delivery of JCV resulted in infection and subsequent demyelination of these chimeric mice. Human GPCs and astrocytes were infected more readily than oligodendrocytes, and viral replication was noted primarily in human astrocytes and GPCs rather than oligodendrocytes, which instead expressed early viral T antigens and exhibited apoptotic death. Engraftment of human GPCs in normally myelinated and immunodeficient mice resulted in humanized white matter that was chimeric for human astrocytes and GPCs. JCV effectively propagated in these mice, which indicates that astroglial infection is sufficient for JCV spread. Sequencing revealed progressive mutation of the JCV capsid protein VP1 after infection, suggesting that PML may evolve with active infection. These results indicate that the principal CNS targets for JCV infection are astrocytes and GPCs and that infection is associated with progressive mutation, while demyelination is a secondary occurrence, following T antigen–triggered oligodendroglial apoptosis. More broadly, this study provides a model by which to further assess the biology and treatment of human-specific gliotropic viruses.
Authors
Yoichi Kondo, Martha S. Windrem, Lisa Zou, Devin Chandler-Militello, Steven J. Schanz, Romane M. Auvergne, Sarah J. Betstadt, Amy R. Harrington, Mahlon Johnson, Alexander Kazarov, Leonid Gorelik, Steven A. Goldman
×Abstract
It has recently been demonstrated that memory B cells can reenter and reengage germinal center (GC) reactions, opening the possibility that multi-hit lymphomagenesis gradually occurs throughout life during successive immunological challenges. Here, we investigated this scenario in follicular lymphoma (FL), an indolent GC-derived malignancy. We developed a mouse model that recapitulates the FL hallmark t(14;18) translocation, which results in constitutive activation of antiapoptotic protein B cell lymphoma 2 (BCL2) in a subset of B cells, and applied a combination of molecular and immunofluorescence approaches to track normal and t(14;18)+ memory B cells in human and BCL2-overexpressing B cells in murine lymphoid tissues. BCL2-overexpressing B cells required multiple GC transits before acquiring FL-associated developmental arrest and presenting as GC B cells with constitutive activation–induced cytidine deaminase (AID) mutator activity. Moreover, multiple reentries into the GC were necessary for the progression to advanced precursor stages of FL. Together, our results demonstrate that protracted subversion of immune dynamics contributes to early dissemination and progression of t(14;18)+ precursors and shapes the systemic presentation of FL patients.
Authors
Stéphanie Sungalee, Emilie Mamessier, Ester Morgado, Emilie Grégoire, Philip Z. Brohawn, Christopher A. Morehouse, Nathalie Jouve, Céline Monvoisin, Cédric Menard, Guilhaume Debroas, Mustapha Faroudi, Violaine Mechin, Jean-Marc Navarro, Charlotte Drevet, Franziska C. Eberle, Lionel Chasson, Fannie Baudimont, Stéphane J. Mancini, Julie Tellier, Jean-Michel Picquenot, Rachel Kelly, Paolo Vineis, Philippe Ruminy, Bruno Chetaille, Elaine S. Jaffe, Claudine Schiff, Jean Hardwigsen, David A. Tice, Brandon W. Higgs, Karin Tarte, Bertrand Nadel, Sandrine Roulland
×Abstract
CD8+ cytotoxic T lymphocytes (CTLs) have potent antitumor activity and therefore are leading candidates for use in tumor immunotherapy. The application of CTLs for clinical use has been limited by the susceptibility of ex vivo–expanded CTLs to become dysfunctional in response to immunosuppressive microenvironments. Here, we developed a microRNA-targeting (miRNA-targeting) approach that augments CTL cytotoxicity and preserves immunocompetence. Specifically, we screened for miRNAs that modulate cytotoxicity and identified miR-23a as a strong functional repressor of the transcription factor BLIMP-1, which promotes CTL cytotoxicity and effector cell differentiation. In a cohort of advanced lung cancer patients, miR-23a was upregulated in tumor-infiltrating CTLs, and expression correlated with impaired antitumor potential of patient CTLs. We determined that tumor-derived TGF-β directly suppresses CTL immune function by elevating miR-23a and downregulating BLIMP-1. Functional blocking of miR-23a in human CTLs enhanced granzyme B expression, and in mice with established tumors, immunotherapy with just a small number of tumor-specific CTLs in which miR-23a was inhibited robustly hindered tumor progression. Together, our findings provide a miRNA-based strategy that subverts the immunosuppression of CTLs that is often observed during adoptive cell transfer tumor immunotherapy and identify a TGF-β–mediated tumor immune-evasion pathway.
Authors
Regina Lin, Ling Chen, Gang Chen, Chunyan Hu, Shan Jiang, Jose Sevilla, Ying Wan, John H. Sampson, Bo Zhu, Qi-Jing Li
×Abstract
Growing evidence supports a link between inflammation and cancer; however, mediators of the transition between inflammation and carcinogenesis remain incompletely understood. Sphingosine-1-phosphate (S1P) lyase (SPL) irreversibly degrades the bioactive sphingolipid S1P and is highly expressed in enterocytes but downregulated in colon cancer. Here, we investigated the role of SPL in colitis-associated cancer (CAC). We generated mice with intestinal epithelium-specific
Sgpl1 deletion and chemically induced colitis and tumor formation in these animals. Compared with control animals, mice lacking intestinal SPL exhibited greater disease activity, colon shortening, cytokine levels, S1P accumulation, tumors, STAT3 activation, STAT3-activated microRNAs (miRNAs), and suppression of miR-targeted anti-oncogene products. This phenotype was attenuated by STAT3 inhibition. In fibroblasts, silencing SPL promoted tumorigenic transformation through a pathway involving extracellular transport of S1P through S1P transporter spinster homolog 2 (SPNS2), S1P receptor activation, JAK2/STAT3-dependent miR-181b-1 induction, and silencing of miR-181b-1 target cylindromatosis (CYLD). Colon biopsies from patients with inflammatory bowel disease revealed enhanced S1P and STAT3 signaling. In mice with chemical-induced CAC, oral administration of plant-type sphingolipids called sphingadienes increased colonic SPL levels and reduced S1P levels, STAT3 signaling, cytokine levels, and tumorigenesis, indicating that SPL prevents transformation and carcinogenesis. Together, our results suggest that dietary sphingolipids can augment or prevent colon cancer, depending upon whether they are metabolized to S1P or promote S1P metabolism through the actions of SPL.Authors
Emilie Degagné, Ashok Pandurangan, Padmavathi Bandhuvula, Ashok Kumar, Abeer Eltanawy, Meng Zhang, Yuko Yoshinaga, Mikhail Nefedov, Pieter J. de Jong, Loren G. Fong, Stephen G. Young, Robert Bittman, Yasmin Ahmedi, Julie D. Saba
×Abstract
Acute stimulation of cardiac β-adrenoceptors is crucial to increasing cardiac function under stress; however, sustained β-adrenergic stimulation has been implicated in pathological myocardial remodeling and heart failure. Here, we have demonstrated that export of cAMP from cardiac myocytes is an intrinsic cardioprotective mechanism in response to cardiac stress. We report that infusion of cAMP into mice averted myocardial hypertrophy and fibrosis in a disease model of cardiac pressure overload. The protective effect of exogenous cAMP required adenosine receptor signaling. This observation led to the identification of a potent paracrine mechanism that is dependent on secreted cAMP. Specifically, FRET-based imaging of cAMP formation in primary cells and in myocardial tissue from murine hearts revealed that cardiomyocytes depend on the transporter ABCC4 to export cAMP as an extracellular signal. Extracellular cAMP, through its metabolite adenosine, reduced cardiomyocyte cAMP formation and hypertrophy by activating A1 adenosine receptors while delivering an antifibrotic signal to cardiac fibroblasts by A2 adenosine receptor activation. Together, our data reveal a paracrine role for secreted cAMP in intercellular signaling in the myocardium, and we postulate that secreted cAMP may also constitute an important signal in other tissues.
Authors
Yassine Sassi, Andrea Ahles, Dong-Jiunn Jeffery Truong, Younis Baqi, Sang-Yong Lee, Britta Husse, Jean-Sébastien Hulot, Ariana Foinquinos, Thomas Thum, Christa E. Müller, Andreas Dendorfer, Bernhard Laggerbauer, Stefan Engelhardt
×Abstract
Intracellular Mg2+ levels are strictly regulated; however, the biological importance of intracellular Mg2+ levels and the pathways that regulate them remain poorly understood. Here, we determined that intracellular Mg2+ is important in regulating both energy metabolism and tumor progression. We determined that CNNM4, a membrane protein that stimulates Mg2+ efflux, binds phosphatase of regenerating liver (PRL), which is frequently overexpressed in malignant human cancers. Biochemical analyses of cultured cells revealed that PRL prevents CNNM4-dependent Mg2+ efflux and that regulation of intracellular Mg2+ levels by PRL and CNNM4 is linked to energy metabolism and AMPK/mTOR signaling. Indeed, treatment with the clinically available mTOR inhibitor rapamycin suppressed the growth of cancer cells in which PRL was overexpressed. In
Apc Δ14/+ mice, which spontaneously form benign polyps in the intestine, deletion of Cnnm4 promoted malignant progression of intestinal polyps to adenocarcinomas. IHC analyses of tissues from patients with colon cancer demonstrated an inverse relationship between CNNM4 expression and colon cancer malignancy. Together, these results indicate that CNNM4-dependent Mg2+ efflux suppresses tumor progression by regulating energy metabolism.Authors
Yosuke Funato, Daisuke Yamazaki, Shin Mizukami, Lisa Du, Kazuya Kikuchi, Hiroaki Miki
×Abstract
Triple-negative breast cancers (TNBCs) are a heterogeneous set of cancers that are defined by the absence of hormone receptor expression and
HER2 amplification. Here, we found that inducible IκB kinase–related (IKK-related) kinase IKBKE expression and JAK/STAT pathway activation compose a cytokine signaling network in the immune-activated subset of TNBC. We found that treatment of cultured IKBKE-driven breast cancer cells with CYT387, a potent inhibitor of TBK1/IKBKE and JAK signaling, impairs proliferation, while inhibition of JAK alone does not. CYT387 treatment inhibited activation of both NF-κB and STAT and disrupted expression of the protumorigenic cytokines CCL5 and IL-6 in these IKBKE-driven breast cancer cells. Moreover, in 3D culture models, the addition of CCL5 and IL-6 to the media not only promoted tumor spheroid dispersal but also stimulated proliferation and migration of endothelial cells. Interruption of cytokine signaling by CYT387 in vivo impaired the growth of an IKBKE-driven TNBC cell line and patient-derived xenografts (PDXs). A combination of CYT387 therapy with a MEK inhibitor was particularly effective, abrogating tumor growth and angiogenesis in an aggressive PDX model of TNBC. Together, these findings reveal that IKBKE-associated cytokine signaling promotes tumorigenicity of immune-driven TNBC and identify a potential therapeutic strategy using clinically available compounds.Authors
Thanh U. Barbie, Gabriela Alexe, Amir R. Aref, Shunqiang Li, Zehua Zhu, Xiuli Zhang, Yu Imamura, Tran C. Thai, Ying Huang, Michaela Bowden, John Herndon, Travis J. Cohoon, Timothy Fleming, Pablo Tamayo, Jill P. Mesirov, Shuji Ogino, Kwok-Kin Wong, Matthew J. Ellis, William C. Hahn, David A. Barbie, William E. Gillanders
×Abstract
The bile acid–responsive G protein–coupled receptor TGR5 is involved in several metabolic processes, and recent studies suggest that TGR5 activation may promote pathways that are protective against diet-induced diabetes. Here, we investigated the role of macrophage-specific TGR5 signaling in protecting adipose tissue from inflammation and associated insulin resistance. Examination of adipose tissue from obese mice lacking macrophage
Tgr5 revealed enhanced inflammation, increased chemokine expression, and higher macrophage numbers compared with control obese animals. Moreover, macrophage-specific deletion ofTgr5 exacerbated insulin resistance in obese animals. Conversely, pharmacological activation of TGR5 markedly decreased LPS-induced chemokine expression in primary macrophages. This reduction was mediated by AKT-dependent activation of mTOR complex 1, which in turn induced the differential translation of the dominant-negative C/EBPβ isoform, liver inhibitory protein (LIP). Overall, these studies reveal a signaling pathway downstream of TGR5 that modulates chemokine expression in response to high-fat diet and suggest that targeting this pathway has the potential to be therapeutically exploited for prevention of chronic inflammatory diseases and type 2 diabetes mellitus.Authors
Alessia Perino, Thijs Willem Hendrik Pols, Mitsunori Nomura, Sokrates Stein, Roberto Pellicciari, Kristina Schoonjans
×Abstract
Many patients who undergo general anesthesia and surgery experience cognitive dysfunction, particularly memory deficits that can persist for days to months. The mechanisms underlying this postoperative cognitive dysfunction in the adult brain remain poorly understood. Depression of brain function during anesthesia is attributed primarily to increased activity of γ-aminobutyric acid type A receptors (GABAARs), and it is assumed that once the anesthetic drug is eliminated, the activity of GABAARs rapidly returns to baseline and these receptors no longer impair memory. Here, using a murine model, we found that a single in vivo treatment with the injectable anesthetic etomidate increased a tonic inhibitory current generated by α5 subunit–containing GABAARs (α5GABAARs) and cell-surface expression of α5GABAARs for at least 1 week. The sustained increase in α5GABAAR activity impaired memory performance and synaptic plasticity in the hippocampus. Inhibition of α5GABAARs completely reversed the memory deficits after anesthesia. Similarly, the inhaled anesthetic isoflurane triggered a persistent increase in tonic current and cell-surface expression of α5GABAARs. Thus, α5GABAAR function does not return to baseline after the anesthetic is eliminated, suggesting a mechanism to account for persistent memory deficits after general anesthesia.
Authors
Agnieszka A. Zurek, Jieying Yu, Dian-Shi Wang, Sean C. Haffey, Erica M. Bridgwater, Antonello Penna, Irene Lecker, Gang Lei, Tom Chang, Eric W.R. Salter, Beverley A. Orser
×Abstract
Atopic dermatitis (AD) and food allergy are closely linked; however, the mechanisms that guide the progression of AD to allergic inflammatory responses at other mucosal surfaces, including the gastrointestinal tract, are not well understood. Here, we determined that exposure of mice that have been epicutaneously sensitized with thymic stromal lymphopoietin (TSLP) and antigen to repeated oral doses of the same antigen induced acute diarrhea and anaphylaxis. In this model, loss of TSLP signaling specifically in DCs led to loss of induced allergic diarrhea through lack of sensitization. While TSLP responses were not required during oral allergen challenge, CD4+ T cells were required and transferred disease when introduced into naive hosts. In addition, oral exposure to the antigen prior to skin sensitization blocked development of allergic disease. Finally, mice lacking the receptor for IL-25 failed to develop acute diarrhea and anaphylaxis, highlighting a role for IL-25 in the initiation of type 2 immunity in the intestine. These results demonstrate a role for TSLP and IL-25 in the atopic march from skin sensitization to food allergic responses and provide a model system for the generation of potential therapeutic interventions.
Authors
Hongwei Han, Tennille D. Thelen, Michael R. Comeau, Steven F. Ziegler
×Abstract
High aldehyde dehydrogenase (ALDH) activity is a marker commonly used to isolate stem cells, particularly breast cancer stem cells (CSCs). Here, we determined that ALDH1A1 activity is inhibited by acetylation of lysine 353 (K353) and that acetyltransferase P300/CBP–associated factor (PCAF) and deacetylase sirtuin 2 (SIRT2) are responsible for regulating the acetylation state of ALDH1A1 K353. Evaluation of breast carcinoma tissues from patients revealed that cells with high ALDH1 activity have low ALDH1A1 acetylation and are capable of self-renewal. Acetylation of ALDH1A1 inhibited both the stem cell population and self-renewal properties in breast cancer. Moreover, NOTCH signaling activated ALDH1A1 through the induction of SIRT2, leading to ALDH1A1 deacetylation and enzymatic activation to promote breast CSCs. In breast cancer xenograft models, replacement of endogenous ALDH1A1 with an acetylation mimetic mutant inhibited tumorigenesis and tumor growth. Together, the results from our study reveal a function and mechanism of ALDH1A1 acetylation in regulating breast CSCs.
Authors
Di Zhao, Yan Mo, Meng-Tian Li, Shao-Wu Zou, Zhou-Li Cheng, Yi-Ping Sun, Yue Xiong, Kun-Liang Guan, Qun-Ying Lei
×Abstract
Infiltrating inflammatory cells are highly prevalent within the tumor microenvironment and mediate many processes associated with tumor progression; however, the contribution of specific populations remains unclear. For example, the nature and function of tumor-associated neutrophils (TANs) in the cancer microenvironment is largely unknown. The goal of this study was to provide a phenotypic and functional characterization of TANs in surgically resected lung cancer patients. We found that TANs constituted 5%–25% of cells isolated from the digested human lung tumors. Compared with blood neutrophils, TANs displayed an activated phenotype (CD62LloCD54hi) with a distinct repertoire of chemokine receptors that included CCR5, CCR7, CXCR3, and CXCR4. TANs produced substantial quantities of the proinflammatory factors MCP-1, IL-8, MIP-1α, and IL-6, as well as the antiinflammatory IL-1R antagonist. Functionally, both TANs and neutrophils isolated from distant nonmalignant lung tissue were able to stimulate T cell proliferation and IFN-γ release. Cross-talk between TANs and activated T cells led to substantial upregulation of CD54, CD86, OX40L, and 4-1BBL costimulatory molecules on the neutrophil surface, which bolstered T cell proliferation in a positive-feedback loop. Together our results demonstrate that in the earliest stages of lung cancer, TANs are not immunosuppressive, but rather stimulate T cell responses.
Authors
Evgeniy B. Eruslanov, Pratik S. Bhojnagarwala, Jon G. Quatromoni, Tom Li Stephen, Anjana Ranganathan, Charuhas Deshpande, Tatiana Akimova, Anil Vachani, Leslie Litzky, Wayne W. Hancock, José R. Conejo-Garcia, Michael Feldman, Steven M. Albelda, Sunil Singhal
×Abstract
Increased synthesis of cervical hyaluronan (HA) from early to late pregnancy has long been proposed to play an essential role in disorganization of the collagen-rich extracellular matrix to allow for maximal compliance and dilation of the cervix during the birth process. Here, we show that HA is not essential for increased cervical distensibility during late pregnancy. Rather, cervicovaginal HA plays an unanticipated important role in epithelial barrier protection of the lower reproductive tract. Specifically, HA depletion in the cervix and vagina resulted in inappropriate differentiation of epithelial cells, increased epithelial and mucosal permeability, and strikingly increased preterm birth rates in a mouse model of ascending vaginal infection. Collectively, these findings revealed that although HA is not obligatory for cervical compliance, it is crucial for maintaining an epithelial and mucosal barrier to limit pathogen infiltration of the lower reproductive tract during pregnancy and thereby is protective against infection-mediated preterm birth.
Authors
Yucel Akgul, R. Ann Word, Laura M. Ensign, Yu Yamaguchi, John Lydon, Justin Hanes, Mala Mahendroo
×LYN-activating mutations mediate antiestrogen resistance in estrogen receptor–positive breast cancer
Abstract
Estrogen receptor–positive (ER+) breast cancers adapt to hormone deprivation and become resistant to antiestrogen therapy. Here, we performed deep sequencing on ER+ tumors that remained highly proliferative after treatment with the aromatase inhibitor letrozole and identified a D189Y mutation in the inhibitory SH2 domain of the SRC family kinase (SFK) LYN. Evaluation of 463 breast tumors in The Cancer Genome Atlas revealed four
LYN mutations, two of which affected the SH2 domain. In addition, LYN was upregulated in multiple ER+ breast cancer lines resistant to long-term estrogen deprivation (LTED). An RNAi-based kinome screen revealed that LYN is required for growth of ER+ LTED breast cancer cells. Kinase assays and immunoblot analyses of SRC substrates in transfected cells indicated that LYND189Y has higher catalytic activity than WT protein. Further, LYND189Y exhibited reduced phosphorylation at the inhibitory Y507 site compared with LYNWT. Other SH2 domain LYN mutants, E159K and K209N, also exhibited higher catalytic activity and reduced inhibitory site phosphorylation. LYND189Y overexpression abrogated growth inhibition by fulvestrant and/or the PI3K inhibitor BKM120 in 3 ER+ breast cancer cell lines. The SFK inhibitor dasatinib enhanced the antitumor effect of BKM120 and fulvestrant against estrogen-deprived ER+ xenografts but not LYND189Y-expressing xenografts. These results suggest that LYN mutations mediate escape from antiestrogens in a subset of ER+ breast cancers.Authors
Luis J. Schwarz, Emily M. Fox, Justin M. Balko, Joan T. Garrett, María Gabriela Kuba, Mónica Valeria Estrada, Ana María González-Angulo, Gordon B. Mills, Monica Red-Brewer, Ingrid A. Mayer, Vandana Abramson, Monica Rizzo, Mark C. Kelley, Ingrid M. Meszoely, Carlos L. Arteaga
×Abstract
Retinoid-storing hepatic stellate cells (HSCs) have recently been described as a liver-resident mesenchymal stem cell (MSC) population; however, it is not clear whether these cells contribute to liver regeneration or serve as a progenitor cell population with hepatobiliary characteristics. Here, we purified HSCs with retinoid-dependent fluorescence-activated cell sorting from eGFP-expressing rats and transplanted these GFP+ HSCs into wild-type (WT) rats that had undergone partial hepatectomy in the presence of 2-acetylaminofluorene (2AAF) or retrorsine, both of which are injury models that favor stem cell–based liver repair. Transplanted HSCs contributed to liver regeneration in host animals by forming mesenchymal tissue, progenitor cells, hepatocytes, and cholangiocytes and elevated direct bilirubin levels in blood sera of GUNN rats, indicating recovery from the hepatic bilirubin–handling defect in these animals. Transplanted HSCs engrafted within the bone marrow (BM) of host animals, and HSC-derived cells were isolated from BM and successfully retransplanted into new hosts with injured liver. Cultured HSCs transiently adopted an expression profile similar to that of progenitor cells during differentiation into bile acid–synthesizing and –transporting hepatocytes, suggesting that stellate cells represent a source of liver progenitor cells. This concept connects seemingly contradictory studies that favor either progenitor cells or MSCs as important players in stem cell–based liver regeneration.
Authors
Claus Kordes, Iris Sawitza, Silke Götze, Diran Herebian, Dieter Häussinger
×Abstract
Innate immunity to viral infection involves induction of the type I IFN response; however, dysfunctional regulation of this pathway leads to inappropriate inflammation. Here, we evaluated a nonconsanguineous family of mixed European descent, with 4 members affected by systemic inflammatory and autoimmune conditions, including lupus, with variable clinical expression. We identified a germline dominant gain-of-function mutation in
TMEM173 , which encodes stimulator of type I IFN gene (STING), in the affected individuals. STING is a key signaling molecule in cytosolic DNA-sensing pathways, and STING activation normally requires dimerization, which is induced by 2′3′ cyclic GMP-AMP (cGAMP) produced by the cGAMP synthase in response to cytosolic DNA. Structural modeling supported constitutive activation of the mutant STING protein based on stabilized dimerization. In agreement with the model predictions, we found that the STING mutant spontaneously localizes in the Golgi of patient fibroblasts and is constitutively active in the absence of exogenous 2′3′-cGAMP in vitro. Accordingly, we observed elevated serum IFN activity and a type I IFN signature in peripheral blood from affected family members. These findings highlight the key role of STING in activating both the innate and adaptive immune responses and implicate aberrant STING activation in features of human lupus.Authors
Nadia Jeremiah, Bénédicte Neven, Matteo Gentili, Isabelle Callebaut, Sophia Maschalidi, Marie-Claude Stolzenberg, Nicolas Goudin, Marie-Louis Frémond, Patrick Nitschke, Thierry J. Molina, Stéphane Blanche, Capucine Picard, Gillian I. Rice, Yanick J. Crow, Nicolas Manel, Alain Fischer, Brigitte Bader-Meunier, Frédéric Rieux-Laucat
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)