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- Volume 127, Issue 3
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On the cover: CHD7 regulates cerebellar development
The chromatin remodeling factor CHD7 is frequently mutated in CHARGE syndrome. Whittaker et al. identify a role for the chromatin remodeling factor CHD7 in the expansion of cerebellar granule progenitor cells. The cover image shows immunostaining of Purkinje cells (red) and DAPI staining of nuclei (blue) in the cerebellar vermis of a 21-day-old wild-type mouse.
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Reviews
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Abstract
Chikungunya virus (CHIKV), a reemerging arbovirus, causes a crippling musculoskeletal inflammatory disease in humans characterized by fever, polyarthralgia, myalgia, rash, and headache. CHIKV is transmitted by
Aedes species of mosquitoes and is capable of an epidemic, urban transmission cycle with high rates of infection. Since 2004, CHIKV has spread to new areas, causing disease on a global scale, and the potential for CHIKV epidemics remains high. Although CHIKV has caused millions of cases of disease and significant economic burden in affected areas, no licensed vaccines or antiviral therapies are available. In this Review, we describe CHIKV epidemiology, replication cycle, pathogenesis and host immune responses, and prospects for effective vaccines and highlight important questions for future research.Authors
Laurie A. Silva, Terence S. Dermody
×Abstract
Hemolysis is a fundamental feature of sickle cell anemia that contributes to its pathophysiology and phenotypic variability. Decompartmentalized hemoglobin, arginase 1, asymmetric dimethylarginine, and adenine nucleotides are all products of hemolysis that promote vasomotor dysfunction, proliferative vasculopathy, and a multitude of clinical complications of pulmonary and systemic vasculopathy, including pulmonary hypertension, leg ulcers, priapism, chronic kidney disease, and large-artery ischemic stroke. Nitric oxide (NO) is inactivated by cell-free hemoglobin in a dioxygenation reaction that also oxidizes hemoglobin to methemoglobin, a non–oxygen-binding form of hemoglobin that readily loses heme. Circulating hemoglobin and heme represent erythrocytic danger-associated molecular pattern (eDAMP) molecules, which activate the innate immune system and endothelium to an inflammatory, proadhesive state that promotes sickle vaso-occlusion and acute lung injury in murine models of sickle cell disease. Intravascular hemolysis can impair NO bioavailability and cause oxidative stress, altering redox balance and amplifying physiological processes that govern blood flow, hemostasis, inflammation, and angiogenesis. These pathological responses promote regional vasoconstriction and subsequent blood vessel remodeling. Thus, intravascular hemolysis represents an intrinsic mechanism for human vascular disease that manifests clinical complications in sickle cell disease and other chronic hereditary or acquired hemolytic anemias.
Authors
Gregory J. Kato, Martin H. Steinberg, Mark T. Gladwin
×Abstract
Many RNA species have been identified as important players in the development of chronic diseases, including cancer. Over the past decade, numerous studies have highlighted how regulatory RNAs such as microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) play crucial roles in the development of a disease state. It is clear that the aberrant expression of miRNAs promotes tumor initiation and progression, is linked with cardiac dysfunction, allows for the improper physiological response in maintaining glucose and insulin levels, and can prevent the appropriate integration of neuronal networks, resulting in neurodegenerative disorders. Because of this, there has been a major effort to therapeutically target these noncoding RNAs. In just the past 5 years, over 100 antisense oligonucleotide–based therapies have been tested in phase I clinical trials, a quarter of which have reached phase II/III. Most notable are fomivirsen and mipomersen, which have received FDA approval to treat cytomegalovirus retinitis and high blood cholesterol, respectively. The continued improvement of innovative RNA modifications and delivery entities, such as nanoparticles, will aid in the development of future RNA-based therapeutics for a broader range of chronic diseases. Here we summarize the latest promises and challenges of targeting noncoding RNAs in disease.
Authors
Brian D. Adams, Christine Parsons, Lisa Walker, Wen Cai Zhang, Frank J. Slack
×Abstract
Regulatory B cells (Bregs) modulate immune responses predominantly, although not exclusively, via the release of IL-10. The importance of human Bregs in the maintenance of immune homeostasis comes from a variety of immune-related pathologies, such as autoimmune diseases, cancers, and chronic infections that are often associated with abnormalities in Breg numbers or function. A continuous effort toward understanding Breg biology in healthy individuals will provide new opportunities to develop Breg immunotherapy that could prove beneficial in treating various immune-mediated pathologies. In this Review, we discuss findings regarding human Bregs, including their mechanisms of suppression and role in different disease settings. We also propose several therapeutic strategies targeting Bregs for better management of immune disorders.
Authors
Claudia Mauri, Madhvi Menon
×Abstract
In addition to being a component of innate immunity and an ancient defense mechanism against invading pathogens, complement activation also participates in the adaptive immune response, inflammation, hemostasis, embryogenesis, and organ repair and development. Activation of the complement system via classical, lectin, or alternative pathways generates anaphylatoxins (C3a and C5a) and membrane attack complex (C5b-9) and opsonizes targeted cells. Complement activation end products and their receptors mediate cell-cell interactions that regulate several biological functions in the extravascular tissue. Signaling of anaphylatoxin receptors or assembly of membrane attack complex promotes cell dedifferentiation, proliferation, and migration in addition to reducing apoptosis. As a result, complement activation in the tumor microenvironment enhances tumor growth and increases metastasis. In this Review, I discuss immune and nonimmune functions of complement proteins and the tumor-promoting effect of complement activation.
Authors
Vahid Afshar-Kharghan
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Commentaries
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Abstract
Blood vessels have a unified mission to circulate blood throughout the body; however, they have additional diverse and specialized roles in various organs. For example, in the liver, discontinuous sinusoids, which are fenestrated capillaries with intercellular gaps and a fragmented basement membrane, facilitate delivery of macromolecules to highly metabolic hepatocytes. During embryonic development, discontinuous sinusoids also allow circulating hematopoietic progenitor and stem cells to populate the liver and promote blood cell differentiation. In this issue of the
JCI , Géraud et al. describe an essential role for the transcription factor GATA4 in promoting the development of discontinuous sinusoids. In the absence of liver sinusoidal GATA4, mouse embryos developed hepatic capillaries with upregulated endothelial cell junction proteins and a continuous basement membrane. These features prevented hematopoietic progenitor cells from transmigrating into the developing liver, andGata4 -mutant embryos died from subsequent liver hypoplasia and anemia. This study highlights the surprising and extensive transcriptional control GATA4 exercises over specialized liver vascular development and function.Authors
Courtney T. Griffin, Siqi Gao
×Abstract
Glucagon-like peptide 1 receptor (GLP-1R) signaling in the CNS has been linked to reduced food intake, lower body weight, improved glucose homeostasis, and activation of CNS stress axes. GLP-1 is produced by cells that express proglucagon (GCG); however, the stimuli that activate GCG+ neurons are not well known, which has made understanding the role of this neuronal population in the CNS a challenge. In this issue of the
JCI , Gaykema et al. use designer receptors exclusively activated by designer drugs (DREADD) technology to specifically activate GCG+ neurons in mouse models. While activation of GCG+ neurons did reduce food intake, and variably decreased hepatic glucose production, other GLP-1–associated effects were not observed — e.g., activation of stress axes or stimulation of insulin secretion — in response to GCG+ neuron activation. The authors have provided a valuable model to study this set of neurons in vivo, and their results provide new insights into the function of GCG+ neural activity in the brain and raise questions that will move research on this clinically relevant neural system forward.Authors
Jonathan E. Campbell, David A. D’Alessio
×Abstract
MicroRNAs (miRNAs) have emerged as important regulators of a variety of biological processes and pathways. In this issue of the
JCI , Ahmed et al. reveal that miR-7a2 is a critical regulator of sexual maturation and reproductive function, as mice lacking miR-7a2 develop hypogonadotropic hypogonadism and infertility. Using a bioinformatics approach, the authors identified several miR-7a2 target genes and pathways that have not been previously associated with gonadotropin biosynthesis and/or secretion. Together, these results identify miR-7a2–regulated genes involved in reproductive hormone biosynthesis pathways and provide a framework for future studies aimed at understanding rare reproductive conditions.Authors
William F. Crowley, Ravi Balasubramanian
×Abstract
Muscular dystrophies result from a defect in the linkage between the muscle fiber cytoskeleton and the basement membrane (BM). Congenital muscular dystrophy type MDC1A is caused by mutations in laminin α2 that either reduce its expression or impair its ability to polymerize within the muscle fiber BM. Defects in this BM lead to muscle fiber damage from the force of contraction. In this issue of the
JCI , McKee and colleagues use a laminin polymerization–competent, designer chimeric BM protein in vivo to restore function of a polymerization-defective laminin, leading to normalized muscle structure and strength in a mouse model of MDC1A. Delivery of such a protein to patients could ameliorate many aspects of their disease.Authors
Steven D. Funk, Jeffrey H. Miner
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Research Articles
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Abstract
Elevated expression of the chemokine receptor CCR4 in tumors is associated with poor prognosis in several cancers. Here, we have determined that CCR4 was highly expressed in human renal cell carcinoma (RCC) biopsies and observed abnormal levels of CCR4 ligands in RCC patient plasma. An antagonistic anti-CCR4 antibody had antitumor activity in the RENCA mouse model of RCC. CCR4 inhibition did not reduce the proportion of infiltrating leukocytes in the tumor microenvironment but altered the phenotype of myeloid cells, increased NK cell and Th1 cytokine levels, and reduced immature myeloid cell infiltrate and blood chemokine levels. In spite of prominent changes in the myeloid compartment, the anti-CCR4 antibody did not affect RENCA tumors in T cell–deficient mice, and treatment with an anti–class II MHC antibody abrogated its antitumor activity. We concluded that the effects of the anti-CCR4 antibody required the adaptive immune system and CD4+ T cells. Moreover, CCL17-induced IFN-γ production was reduced when Th1-polarized normal CD4+ T cells were exposed to the CCR4 ligand, evidencing the involvement of CCR4 in Th1/Th2 regulation. The anti-CCR4 antibody, alone or in combination with other immune modulators, is a potential treatment approach to human solid cancers with high levels of CCR4-expressing tumor-infiltrating leukocytes and abnormal plasma CCR4 ligand levels.
Authors
Chiara Berlato, Moddasar N. Khan, Tiziana Schioppa, Richard Thompson, Eleni Maniati, Anne Montfort, Maryam Jangani, Monica Canosa, Hagen Kulbe, Urs B. Hagemann, Alexander R. Duncan, Laura Fletcher, Robert W. Wilkinson, Thomas Powles, Sergio A. Quezada, Frances R. Balkwill
×Abstract
Platelets are anuclear cells that are essential for blood clotting. They are produced by large polyploid precursor cells called megakaryocytes. Previous genome-wide association studies in nearly 70,000 individuals indicated that single nucleotide variants (SNVs) in the gene encoding the actin cytoskeletal regulator tropomyosin 4 (TPM4) exert an effect on the count and volume of platelets. Platelet number and volume are independent risk factors for heart attack and stroke. Here, we have identified 2 unrelated families in the BRIDGE Bleeding and Platelet Disorders (BPD) collection who carry a
TPM4 variant that causes truncation of the TPM4 protein and segregates with macrothrombocytopenia, a disorder characterized by low platelet count.N -Ethyl-N -nitrosourea–induced (ENU-induced) missense mutations inTpm4 or targeted inactivation of theTpm4 locus led to gene dosage–dependent macrothrombocytopenia in mice. All other blood cell counts inTpm4 -deficient mice were normal. Insufficient TPM4 expression in human and mouse megakaryocytes resulted in a defect in the terminal stages of platelet production and had a mild effect on platelet function. Together, our findings demonstrate a nonredundant role forTPM4 in platelet biogenesis in humans and mice and reveal that truncating variants inTPM4 cause a previously undescribed dominant Mendelian platelet disorder.Authors
Irina Pleines, Joanne Woods, Stephane Chappaz, Verity Kew, Nicola Foad, José Ballester-Beltrán, Katja Aurbach, Chiara Lincetto, Rachael M. Lane, Galina Schevzov, Warren S. Alexander, Douglas J. Hilton, William J. Astle, Kate Downes, Paquita Nurden, Sarah K. Westbury, Andrew D. Mumford, Samya G. Obaji, Peter W. Collins, NIHR BioResource, Fabien Delerue, Lars M. Ittner, Nicole S. Bryce, Mira Holliday, Christine A. Lucas, Edna C. Hardeman, Willem H. Ouwehand, Peter W. Gunning, Ernest Turro, Marloes R. Tijssen, Benjamin T. Kile
×Abstract
Disruption of the retinoblastoma (RB) tumor suppressor pathway, either through genetic mutation of upstream regulatory components or mutation of
RB1 itself, is believed to be a required event in cancer. However, genetic alterations in the RB-regulated E2F family of transcription factors are infrequent, casting doubt on a direct role for E2Fs in driving cancer. In this work, a mutation analysis of human cancer revealed subtle but impactful copy number gains inE2F1 andE2F3 in hepatocellular carcinoma (HCC). Using a series of loss- and gain-of-function alleles to dial E2F transcriptional output, we have shown that copy number gains inE2f1 orE2f3b resulted in dosage-dependent spontaneous HCC in mice without the involvement of additional organs. Conversely, germ-line loss ofE2f1 orE2f3b , but notE2f3a , protected mice against HCC. Combinatorial mapping of chromatin occupancy and transcriptome profiling identified an E2F1- and E2F3B-driven transcriptional program that was associated with development and progression of HCC. These findings demonstrate a direct and cell-autonomous role for E2F activators in human cancer.Authors
Lindsey N. Kent, Sooin Bae, Shih-Yin Tsai, Xing Tang, Arunima Srivastava, Christopher Koivisto, Chelsea K. Martin, Elisa Ridolfi, Grace C. Miller, Sarah M. Zorko, Emilia Plevris, Yannis Hadjiyannis, Miguel Perez, Eric Nolan, Raleigh Kladney, Bart Westendorp, Alain de Bruin, Soledad Fernandez, Thomas J. Rosol, Kamal S. Pohar, James M. Pipas, Gustavo Leone
×Abstract
Type I IFNs promote cellular responses to viruses, and IFN receptor (IFNAR) signaling regulates the responses of endothelial cells of the blood-brain barrier (BBB) during neurotropic viral infection. However, the role of astrocytes in innate immune responses of the BBB during viral infection of the CNS remains to be fully elucidated. Here, we have demonstrated that type I IFNAR signaling in astrocytes regulates BBB permeability and protects the cerebellum from infection and immunopathology. Mice with astrocyte-specific loss of IFNAR signaling showed decreased survival after West Nile virus infection. Accelerated mortality was not due to expanded viral tropism or increased replication. Rather, viral entry increased specifically in the hindbrain of IFNAR-deficient mice, suggesting that IFNAR signaling critically regulates BBB permeability in this brain region. Pattern recognition receptors and IFN-stimulated genes had higher basal and IFN-induced expression in human and mouse cerebellar astrocytes than did cerebral cortical astrocytes, suggesting that IFNAR signaling has brain region–specific roles in CNS immune responses. Taken together, our data identify cerebellar astrocytes as key responders to viral infection and highlight the existence of distinct innate immune programs in astrocytes from evolutionarily disparate regions of the CNS.
Authors
Brian P. Daniels, Harsha Jujjavarapu, Douglas M. Durrant, Jessica L. Williams, Richard R. Green, James P. White, Helen M. Lazear, Michael Gale Jr., Michael S. Diamond, Robyn S. Klein
×Abstract
Long-acting anti-HIV products can substantively change the standard of care for patients with HIV/AIDS. To this end, hydrophobic antiretroviral drugs (ARVs) were recently developed for parenteral administration at monthly or longer intervals. While shorter-acting hydrophilic drugs can be made into nanocarrier-encased prodrugs, the nanocarrier encasement must be boosted to establish long-acting ARV depots. The mixed-lineage kinase 3 (MLK-3) inhibitor URMC-099 provides this function by affecting autophagy. Here, we have shown that URMC-099 facilitates ARV sequestration and its antiretroviral responses by promoting the nuclear translocation of the transcription factor EB (TFEB). In monocyte-derived macrophages, URMC-099 induction of autophagy led to retention of nanoparticles containing the antiretroviral protease inhibitor atazanavir. These nanoparticles were localized within macrophage autophagosomes, leading to a 4-fold enhancement of mitochondrial and cell vitality. In rodents, URMC-099 activation of autophagy led to 50-fold increases in the plasma drug concentration of the viral integrase inhibitor dolutegravir. These data paralleled URMC-099–mediated induction of autophagy and the previously reported antiretroviral responses in HIV-1–infected humanized mice. We conclude that pharmacologic induction of autophagy provides a means to extend the action of a long-acting, slow, effective release of antiretroviral therapy.
Authors
Divya Prakash Gnanadhas, Prasanta K. Dash, Brady Sillman, Aditya N. Bade, Zhiyi Lin, Diana L. Palandri, Nagsen Gautam, Yazen Alnouti, Harris A. Gelbard, JoEllyn McMillan, R. Lee Mosley, Benson Edagwa, Howard E. Gendelman, Santhi Gorantla
×The chromatin remodeling factor CHD7 controls cerebellar development by regulating reelin expression
Abstract
The mechanisms underlying the neurodevelopmental deficits associated with CHARGE syndrome, which include cerebellar hypoplasia, developmental delay, coordination problems, and autistic features, have not been identified. CHARGE syndrome has been associated with mutations in the gene encoding the ATP-dependent chromatin remodeler CHD7. CHD7 is expressed in neural stem and progenitor cells, but its role in neurogenesis during brain development remains unknown. Here we have shown that deletion of
Chd7 from cerebellar granule cell progenitors (GCps) results in reduced GCp proliferation, cerebellar hypoplasia, developmental delay, and motor deficits in mice. Genome-wide expression profiling revealed downregulated expression of the gene encoding the glycoprotein reelin (Reln ) inChd7 -deficient GCps. RecessiveRELN mutations have been associated with severe cerebellar hypoplasia in humans. We found molecular and genetic evidence that reductions inReln expression contribute to GCp proliferative defects and cerebellar hypoplasia in GCp-specificChd7 mouse mutants. Finally, we showed that CHD7 is necessary for maintaining an open, accessible chromatin state at theReln locus. Taken together, this study shows thatReln gene expression is regulated by chromatin remodeling, identifies CHD7 as a previously unrecognized upstream regulator ofReln , and provides direct in vivo evidence that a mammalian CHD protein can control brain development by modulating chromatin accessibility in neuronal progenitors.Authors
Danielle E. Whittaker, Kimberley L.H. Riegman, Sahrunizam Kasah, Conor Mohan, Tian Yu, Blanca Pijuan Sala, Husam Hebaishi, Angela Caruso, Ana Claudia Marques, Caterina Michetti, María Eugenia Sanz Smachetti, Apar Shah, Mara Sabbioni, Omer Kulhanci, Wee-Wei Tee, Danny Reinberg, Maria Luisa Scattoni, Holger Volk, Imelda McGonnell, Fiona C. Wardle, Cathy Fernandes, M. Albert Basson
×Abstract
The most frequent focal alterations in human retinoblastoma are mutations in the tumor-suppressor gene retinoblastoma (
RB ) and amplification of the oncogeneMYCN . WhetherMYCN overexpression drives retinoblastoma has not been assessed in model systems. Here, we have shown thatRb inactivation collaborates strongly withMYCN overexpression and leads to retinoblastoma in mice. Overexpression of humanMYCN in the context ofRb inactivation increased the expression of MYC-, E2F-, and ribosome-related gene sets, promoted excessive proliferation, and led to retinoblastoma with anaplastic changes. We then modeled responses to MYCN-directed therapy by suppressingMYCN expression inMYCN -driven retinoblastomas. Initially,MYCN suppression led to proliferation arrest and partial tumor regression with loss of anaplasia. However, over time, retinoblastomas reemerged, typically without reactivation of humanMYCN or amplification of murineMycn . A subset of returning retinoblastomas showed genomic amplification of aMycn target gene encoding the miR cluster miR-17~92, while most retinoblastomas reemerged without clear genetic alterations in eitherMycn or knownMycn targets. ThisRb/MYCN model recapitulates key genetic driver alterations seen in human retinoblastoma and reveals the emergence ofMYCN independence in an initiallyMYCN -driven tumor.Authors
Nan Wu, Deshui Jia, Breanna Bates, Ryan Basom, Charles G. Eberhart, David MacPherson
×Abstract
Ischemic heart disease resulting from myocardial infarction (MI) is the most prevalent form of heart disease in the United States. Post-MI cardiac remodeling is a multifaceted process that includes activation of fibroblasts and a complex immune response. T-regulatory cells (Tregs), a subset of CD4+ T cells, have been shown to suppress the innate and adaptive immune response and limit deleterious remodeling following myocardial injury. However, the mechanisms by which injured myocardium recruits suppressive immune cells remain largely unknown. Here, we have shown a role for Hippo signaling in the epicardium in suppressing the post-infarct inflammatory response through recruitment of Tregs. Mice deficient in epicardial YAP and TAZ, two core Hippo pathway effectors, developed profound post-MI pericardial inflammation and myocardial fibrosis, resulting in cardiomyopathy and death. Mutant mice exhibited fewer suppressive Tregs in the injured myocardium and decreased expression of the gene encoding IFN-γ, a known Treg inducer. Furthermore, controlled local delivery of IFN-γ following MI rescued Treg infiltration into the injured myocardium of YAP/TAZ mutants and decreased fibrosis. Collectively, these results suggest that epicardial Hippo signaling plays a key role in adaptive immune regulation during the post-MI recovery phase.
Authors
Vimal Ramjee, Deqiang Li, Lauren J. Manderfield, Feiyan Liu, Kurt A. Engleka, Haig Aghajanian, Christopher B. Rodell, Wen Lu, Vivienne Ho, Tao Wang, Li Li, Anamika Singh, Dasan M. Cibi, Jason A. Burdick, Manvendra K. Singh, Rajan Jain, Jonathan A. Epstein
×Mutations in sphingosine-1-phosphate lyase cause nephrosis with ichthyosis and adrenal insufficiency
Abstract
Steroid-resistant nephrotic syndrome (SRNS) causes 15% of chronic kidney disease cases. A mutation in 1 of over 40 monogenic genes can be detected in approximately 30% of individuals with SRNS whose symptoms manifest before 25 years of age. However, in many patients, the genetic etiology remains unknown. Here, we have performed whole exome sequencing to identify recessive causes of SRNS. In 7 families with SRNS and facultative ichthyosis, adrenal insufficiency, immunodeficiency, and neurological defects, we identified 9 different recessive mutations in
SGPL1 , which encodes sphingosine-1-phosphate (S1P) lyase. All mutations resulted in reduced or absent SGPL1 protein and/or enzyme activity. Overexpression of cDNA representingSGPL1 mutations resulted in subcellular mislocalization of SGPL1. Furthermore, expression of WT human SGPL1 rescued growth of SGPL1-deficientdpl1 Δ yeast strains, whereas expression of disease-associated variants did not. Immunofluorescence revealed SGPL1 expression in mouse podocytes and mesangial cells. Knockdown ofSgpl1 in rat mesangial cells inhibited cell migration, which was partially rescued by VPC23109, an S1P receptor antagonist. InDrosophila ,Sply mutants, which lack SGPL1, displayed a phenotype reminiscent of nephrotic syndrome in nephrocytes. WTSply , but not the disease-associated variants, rescued this phenotype. Together, these results indicate thatSGPL1 mutations cause a syndromic form of SRNS.Authors
Svjetlana Lovric, Sara Goncalves, Heon Yung Gee, Babak Oskouian, Honnappa Srinivas, Won-Il Choi, Shirlee Shril, Shazia Ashraf, Weizhen Tan, Jia Rao, Merlin Airik, David Schapiro, Daniela A. Braun, Carolin E. Sadowski, Eugen Widmeier, Tilman Jobst-Schwan, Johanna Magdalena Schmidt, Vladimir Girik, Guido Capitani, Jung H. Suh, Noëlle Lachaussée, Christelle Arrondel, Julie Patat, Olivier Gribouval, Monica Furlano, Olivia Boyer, Alain Schmitt, Vincent Vuiblet, Seema Hashmi, Rainer Wilcken, Francois P. Bernier, A. Micheil Innes, Jillian S. Parboosingh, Ryan E. Lamont, Julian P. Midgley, Nicola Wright, Jacek Majewski, Martin Zenker, Franz Schaefer, Navina Kuss, Johann Greil, Thomas Giese, Klaus Schwarz, Vilain Catheline, Denny Schanze, Ingolf Franke, Yves Sznajer, Anne S. Truant, Brigitte Adams, Julie Désir, Ronald Biemann, York Pei, Elisabet Ars, Nuria Lloberas, Alvaro Madrid, Vikas R. Dharnidharka, Anne M. Connolly, Marcia C. Willing, Megan A. Cooper, Richard P. Lifton, Matias Simons, Howard Riezman, Corinne Antignac, Julie D. Saba, Friedhelm Hildebrandt
×Abstract
Chimeric antigen receptor (CAR) T cells have been highly successful in treating hematological malignancies, including acute and chronic lymphoblastic leukemia. However, treatment of solid tumors using CAR T cells has been largely unsuccessful to date, partly because of tumor-induced immunosuppressive mechanisms, including adenosine production. Previous studies have shown that adenosine generated by tumor cells potently inhibits endogenous antitumor T cell responses through activation of adenosine 2A receptors (A2ARs). Herein, we have observed that CAR activation resulted in increased A2AR expression and suppression of both murine and human CAR T cells. This was reversible using either A2AR antagonists or genetic targeting of A2AR using shRNA. In 2 syngeneic HER2+ self-antigen tumor models, we found that either genetic or pharmacological targeting of the A2AR profoundly increased CAR T cell efficacy, particularly when combined with PD-1 blockade. Mechanistically, this was associated with increased cytokine production of CD8+ CAR T cells and increased activation of both CD8+ and CD4+ CAR T cells. Given the known clinical relevance of the CD73/adenosine pathway in several solid tumor types, and the initiation of phase I trials for A2AR antagonists in oncology, this approach has high translational potential to enhance CAR T cell efficacy in several cancer types.
Authors
Paul A. Beavis, Melissa A. Henderson, Lauren Giuffrida, Jane K. Mills, Kevin Sek, Ryan S. Cross, Alexander J. Davenport, Liza B. John, Sherly Mardiana, Clare Y. Slaney, Ricky W. Johnstone, Joseph A. Trapani, John Stagg, Sherene Loi, Lev Kats, David Gyorki, Michael H. Kershaw, Phillip K. Darcy
×Abstract
Primary adrenal insufficiency is life threatening and can present alone or in combination with other comorbidities. Here, we have described a primary adrenal insufficiency syndrome and steroid-resistant nephrotic syndrome caused by loss-of-function mutations in sphingosine-1-phosphate lyase (SGPL1). SGPL1 executes the final decisive step of the sphingolipid breakdown pathway, mediating the irreversible cleavage of the lipid-signaling molecule sphingosine-1-phosphate (S1P). Mutations in other upstream components of the pathway lead to harmful accumulation of lysosomal sphingolipid species, which are associated with a series of conditions known as the sphingolipidoses. In this work, we have identified 4 different homozygous mutations, c.665G>A (p.R222Q), c.1633_1635delTTC (p.F545del), c.261+1G>A (p.S65Rfs*6), and c.7dupA (p.S3Kfs*11), in 5 families with the condition. In total, 8 patients were investigated, some of whom also manifested other features, including ichthyosis, primary hypothyroidism, neurological symptoms, and cryptorchidism.
Sgpl1–/– mice recapitulated the main characteristics of the human disease with abnormal adrenal and renal morphology.Sgpl1–/– mice displayed disrupted adrenocortical zonation and defective expression of steroidogenic enzymes as well as renal histology in keeping with a glomerular phenotype. In summary, we have identifiedSGPL1 mutations in humans that perhaps represent a distinct multisystemic disorder of sphingolipid metabolism.Authors
Rathi Prasad, Irene Hadjidemetriou, Avinaash Maharaj, Eirini Meimaridou, Federica Buonocore, Moin Saleem, Jenny Hurcombe, Agnieszka Bierzynska, Eliana Barbagelata, Ignacio Bergadá, Hamilton Cassinelli, Urmi Das, GOSgene, Ruth Krone, Bulent Hacihamdioglu, Erkan Sari, Ediz Yesilkaya, Helen L. Storr, Maria Clemente, Monica Fernandez-Cancio, Nuria Camats, Nanik Ram, John C. Achermann, Paul P. Van Veldhoven, Leonardo Guasti, Debora Braslavsky, Tulay Guran, Louise A. Metherell
×Abstract
Defective apoptotic death of activated macrophages has been implicated in the pathogenesis of rheumatoid arthritis (RA). However, the molecular signatures defining apoptotic resistance of RA macrophages are not fully understood. Here, global transcriptome profiling of RA macrophages revealed that the osmoprotective transcription factor nuclear factor of activated T cells 5 (NFAT5) critically regulates diverse pathologic processes in synovial macrophages including the cell cycle, apoptosis, and proliferation. Transcriptomic analysis of NFAT5-deficient macrophages revealed the molecular networks defining cell survival and proliferation. Proinflammatory M1-polarizing stimuli and hypoxic conditions were responsible for enhanced NFAT5 expression in RA macrophages. An in vitro functional study demonstrated that NFAT5-deficient macrophages were more susceptible to apoptotic death. Specifically, CCL2 secretion in an NFAT5-dependent fashion bestowed apoptotic resistance to RA macrophages in vitro. Injection of recombinant CCL2 into one of the affected joints of
Nfat5+/– mice increased joint destruction and macrophage infiltration, demonstrating the essential role of the NFAT5/CCL2 axis in arthritis progression in vivo. Moreover, after intra-articular injection, NFAT5-deficient macrophages were more susceptible to apoptosis and less efficient at promoting joint destruction than were NFAT5-sufficient macrophages. Thus, NFAT5 regulates macrophage survival by inducing CCL2 secretion. Our results provide evidence that NFAT5 expression in macrophages enhances chronic arthritis by conferring apoptotic resistance to activated macrophages.Authors
Susanna Choi, Sungyong You, Donghyun Kim, Soo Youn Choi, H. Moo Kwon, Hyun-Sook Kim, Daehee Hwang, Yune-Jung Park, Chul-Soo Cho, Wan-Uk Kim
×Abstract
An intracellular complement system (ICS) has recently been described in immune and nonimmune human cells. This system can be activated in a convertase-independent manner from intracellular stores of the complement component C3. The source of these stores has not been rigorously investigated. In the present study, Western blotting identified a band corresponding to C3 in freshly isolated human peripheral blood cells that was absent in corresponding cell lines. One difference between native cells and cell lines was the time absent from a fluid-phase complement source; therefore, we hypothesized that loading C3 from plasma was a route of establishing intracellular C3 stores. We found that many types of human cells specifically internalized C3(H2O), the hydrolytic product of C3, and not native C3, from the extracellular milieu. Uptake was rapid, saturable, and sensitive to competition with unlabeled C3(H2O), indicating a specific mechanism of loading. Under steady-state conditions, approximately 80% of incorporated C3(H2O) was returned to the extracellular space. These studies identify an ICS recycling pathway for C3(H2O). The loaded C3(H2O) represents a source of C3a, and its uptake altered the cytokine profile of activated CD4+ T cells. Importantly, these results indicate that the impact of soluble plasma factors should be considered when performing in vitro studies assessing cellular immune function.
Authors
Michelle Elvington, M. Kathryn Liszewski, Paula Bertram, Hrishikesh S. Kulkarni, John P. Atkinson
×Abstract
Germline coding mutations in different telomere-related genes have been linked to autosomal-dominant familial pulmonary fibrosis. Individuals with these inherited mutations demonstrate incomplete penetrance of clinical phenotypes affecting the lung, blood, liver, skin, and other organs. Here, we describe the somatic acquisition of promoter mutations in telomerase reverse transcriptase (TERT) in blood leukocytes of approximately 5% of individuals with inherited loss-of-function coding mutations in TERT or poly(A)-specific ribonuclease (PARN), another gene linked to telomerase function. While these promoter mutations were initially identified as oncogenic drivers of cancer, individuals expressing the mutations have no history of cancer. Neither promoter mutation was found in population-based cohorts of similar or advanced age. The TERT promoter mutations were found more frequently in cis with the WT allele than the TERT coding sequence mutation. EBV-transformed lymphoblastoid B cell lines (LCLs) derived from subjects with TERT promoter mutations showed increased telomerase expression and activity compared with cell lines from family members with identical coding mutations. TERT promoter mutations resulted in an increased proliferation of LCLs and demonstrated positive selection over time. The persistence and recurrence of noncoding gain-of-function mutations in these cases suggests that telomerase activation is not only safely tolerated but also advantageous for clonal expansion.
Authors
Lindley Maryoung, Yangbo Yue, Ashley Young, Chad A. Newton, Cindy Barba, Nicolai S.C. van Oers, Richard C. Wang, Christine Kim Garcia
×Abstract
A highly orchestrated gene expression program establishes the properties that define mature adipocytes, but the contribution of posttranscriptional factors to the adipocyte phenotype is poorly understood. Here we have shown that the RNA-binding protein PSPC1, a component of the paraspeckle complex, promotes adipogenesis in vitro and is important for mature adipocyte function in vivo. Cross-linking and immunoprecipitation followed by RNA sequencing revealed that PSPC1 binds to intronic and 3′-untranslated regions of a number of adipocyte RNAs, including the RNA encoding the transcriptional regulator EBF1. Purification of the paraspeckle complex from adipocytes further showed that PSPC1 associates with the RNA export factor DDX3X in a differentiation-dependent manner. Remarkably, PSPC1 relocates from the nucleus to the cytoplasm during differentiation, coinciding with enhanced export of adipogenic RNAs. Mice lacking PSPC1 in fat displayed reduced lipid storage and adipose tissue mass and were resistant to diet-induced obesity and insulin resistance due to a compensatory increase in energy expenditure. These findings highlight a role for PSPC1-dependent RNA maturation in the posttranscriptional control of adipose development and function.
Authors
Jiexin Wang, Prashant Rajbhandari, Andrey Damianov, Areum Han, Tamer Sallam, Hironori Waki, Claudio J. Villanueva, Stephen D. Lee, Ronni Nielsen, Susanne Mandrup, Karen Reue, Stephen G. Young, Julian Whitelegge, Enrique Saez, Douglas L. Black, Peter Tontonoz
×Abstract
Munc13 proteins are essential regulators of neurotransmitter release at nerve cell synapses. They mediate the priming step that renders synaptic vesicles fusion-competent, and their genetic elimination causes a complete block of synaptic transmission. Here we have described a patient displaying a disorder characterized by a dyskinetic movement disorder, developmental delay, and autism. Using whole-exome sequencing, we have shown that this condition is associated with a rare, de novo Pro814Leu variant in the major human Munc13 paralog UNC13A (also known as Munc13-1). Electrophysiological studies in murine neuronal cultures and functional analyses in
Caenorhabditis elegans revealed that the UNC13A variant causes a distinct dominant gain of function that is characterized by increased fusion propensity of synaptic vesicles, which leads to increased initial synaptic vesicle release probability and abnormal short-term synaptic plasticity. Our study underscores the critical importance of fine-tuned presynaptic control in normal brain function. Further, it adds the neuronal Munc13 proteins and the synaptic vesicle priming process that they control to the known etiological mechanisms of psychiatric and neurological synaptopathies.Authors
Noa Lipstein, Nanda M. Verhoeven-Duif, Francesco E. Michelassi, Nathaniel Calloway, Peter M. van Hasselt, Katarzyna Pienkowska, Gijs van Haaften, Mieke M. van Haelst, Ron van Empelen, Inge Cuppen, Heleen C. van Teeseling, Annemieke M.V. Evelein, Jacob A. Vorstman, Sven Thoms, Olaf Jahn, Karen J. Duran, Glen R. Monroe, Timothy A. Ryan, Holger Taschenberger, Jeremy S. Dittman, Jeong-Seop Rhee, Gepke Visser, Judith J. Jans, Nils Brose
×Abstract
Tissue inflammation is a key component of obesity-induced insulin resistance, with a variety of immune cell types accumulating in adipose tissue. Here, we have demonstrated increased numbers of B2 lymphocytes in obese adipose tissue and have shown that high-fat diet–induced (HFD-induced) insulin resistance is mitigated in B cell-deficient (Bnull) mice. Adoptive transfer of adipose tissue B2 cells (ATB2) from wild-type HFD donor mice into HFD Bnull recipients completely restored the effect of HFD to induce insulin resistance. Recruitment and activation of ATB2 cells was mediated by signaling through the chemokine leukotriene B4 (LTB4) and its receptor LTB4R1. Furthermore, the adverse effects of ATB2 cells on glucose homeostasis were partially dependent upon T cells and macrophages. These results demonstrate the importance of ATB2 cells in obesity-induced insulin resistance and suggest that inhibition of the LTB4/LTB4R1 axis might be a useful approach for developing insulin-sensitizing therapeutics.
Authors
Wei Ying, Joshua Wollam, Jachelle M. Ofrecio, Gautam Bandyopadhyay, Dalila El Ouarrat, Yun Sok Lee, Da Young Oh, Pingping Li, Olivia Osborn, Jerrold M. Olefsky
×Abstract
Peptides derived from pre-proglucagon (GCG peptides) act in both the periphery and the CNS to change food intake, glucose homeostasis, and metabolic rate while playing a role in anxiety behaviors and physiological responses to stress. Although the actions of GCG peptides produced in the gut and pancreas are well described, the role of glutamatergic GGC peptide–secreting hindbrain neurons in regulating metabolic homeostasis has not been investigated. Here, we have shown that chemogenetic stimulation of GCG-producing neurons reduces metabolic rate and food intake in fed and fasted states and suppresses glucose production without an effect on glucose uptake. Stimulation of GCG neurons had no effect on corticosterone secretion, body weight, or conditioned taste aversion. In the diet-induced obese state, the effects of GCG neuronal stimulation on gluconeogenesis were lost, while the food intake–lowering effects remained, resulting in reductions in body weight and adiposity. Our work suggests that GCG peptide–expressing neurons can alter feeding, metabolic rate, and glucose production independent of their effects on hypothalamic pituitary-adrenal (HPA) axis activation, aversive conditioning, or insulin secretion. We conclude that GCG neurons likely stimulate separate populations of downstream cells to produce a change in food intake and glucose homeostasis and that these effects depend on the metabolic state of the animal.
Authors
Ronald P. Gaykema, Brandon A. Newmyer, Matteo Ottolini, Vidisha Raje, Daniel M. Warthen, Philip S. Lambeth, Maria Niccum, Ting Yao, Yiru Huang, Ira G. Schulman, Thurl E. Harris, Manoj K. Patel, Kevin W. Williams, Michael M. Scott
×Abstract
Autoimmune responses to meiotic germ cell antigens (MGCA) that are expressed on sperm and testis occur in human infertility and after vasectomy. Many MGCA are also expressed as cancer/testis antigens (CTA) in human cancers, but the tolerance status of MGCA has not been investigated. MGCA are considered to be uniformly immunogenic and nontolerogenic, and the prevailing view posits that MGCA are sequestered behind the Sertoli cell barrier in seminiferous tubules. Here, we have shown that only some murine MGCA are sequestered. Nonsequestered MCGA (NS-MGCA) egressed from normal tubules, as evidenced by their ability to interact with systemically injected antibodies and form localized immune complexes outside the Sertoli cell barrier. NS-MGCA derived from cell fragments that were discarded by spermatids during spermiation. They egressed as cargo in residual bodies and maintained Treg-dependent physiological tolerance. In contrast, sequestered MGCA (S-MGCA) were undetectable in residual bodies and were nontolerogenic. Unlike postvasectomy autoantibodies, which have been shown to mainly target S-MGCA, autoantibodies produced by normal mice with transient Treg depletion that developed autoimmune orchitis exclusively targeted NS-MGCA. We conclude that spermiation, a physiological checkpoint in spermatogenesis, determines the egress and tolerogenicity of MGCA. Our findings will affect target antigen selection in testis and sperm autoimmunity and the immune responses to CTA in male cancer patients.
Authors
Kenneth S.K. Tung, Jessica Harakal, Hui Qiao, Claudia Rival, Jonathan C.H. Li, Alberta G.A. Paul, Karen Wheeler, Patcharin Pramoonjago, Constance M. Grafer, Wei Sun, Robert D. Sampson, Elissa W.P. Wong, Prabhakara P. Reddi, Umesh S. Deshmukh, Daniel M. Hardy, Huanghui Tang, C. Yan Cheng, Erwin Goldberg
×Abstract
MicroRNAs (miRNAs) are negative modulators of gene expression that fine-tune numerous biological processes. miRNA loss-of-function rarely results in highly penetrant phenotypes, but rather, influences cellular responses to physiologic and pathophysiologic stresses. Here, we have reported that a single member of the evolutionarily conserved miR-7 family, miR-7a2, is essential for normal pituitary development and hypothalamic-pituitary-gonadal (HPG) function in adulthood. Genetic deletion of
mir-7a2 causes infertility, with low levels of gonadotropic and sex steroid hormones, small testes or ovaries, impaired spermatogenesis, and lack of ovulation in male and female mice, respectively. We found that miR-7a2 is highly expressed in the pituitary, where it suppresses golgi glycoprotein 1 (GLG1) expression and downstream bone morphogenetic protein 4 (BMP4) signaling and also reduces expression of the prostaglandin F2a receptor negative regulator (PTGFRN), an inhibitor of prostaglandin signaling and follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion. Our results reveal that miR-7a2 critically regulates sexual maturation and reproductive function by interconnecting miR-7 genomic circuits that regulate FSH and LH synthesis and secretion through their effects on pituitary prostaglandin and BMP4 signaling.Authors
Kashan Ahmed, Mary P. LaPierre, Emanuel Gasser, Rémy Denzler, Yinjie Yang, Thomas Rülicke, Jukka Kero, Mathieu Latreille, Markus Stoffel
×Abstract
Mutations in laminin α2-subunit (Lmα2, encoded by
LAMA2 ) are linked to approximately 30% of congenital muscular dystrophy cases. Mice with a homozygous mutation inLama2 (dy2J mice) express a nonpolymerizing form of laminin-211 (Lm211) and are a model for ambulatory-type Lmα2-deficient muscular dystrophy. Here, we developed transgenicdy2J mice with muscle-specific expression of αLNNd, a laminin/nidogen chimeric protein that provides a missing polymerization domain. Muscle-specific expression of αLNNd indy2J mice resulted in strong amelioration of the dystrophic phenotype, manifested by the prevention of fibrosis and restoration of forelimb grip strength. αLNNd also restored myofiber shape, size, and numbers to control levels indy2J mice. Laminin immunostaining and quantitation of tissue extractions revealed increased Lm211 expression in αLNNd-transgenicdy2J mice. In cultured myotubes, we determined that αLNNd expression increased myotube surface accumulation of polymerization-deficient recombinant laminins, with retention of collagen IV, reiterating the basement membrane (BM) changes observed in vivo. Laminin LN domain mutations linked to several of the Lmα2-deficient muscular dystrophies are predicted to compromise polymerization. The data herein support the hypothesis that engineered expression of αLNNd can overcome polymerization deficits to increase laminin, stabilize BM structure, and substantially ameliorate muscular dystrophy.Authors
Karen K. McKee, Stephanie C. Crosson, Sarina Meinen, Judith R. Reinhard, Markus A. Rüegg, Peter D. Yurchenco
×Abstract
Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder initiated by antibodies against complexes between human platelet factor 4 (hPF4) and heparin. A better understanding of the events that initiate the prothrombotic state may improve approaches to antithrombotic management. Here, we visualized thrombus formation in an in vivo murine model and an endothelialized microfluidic system that simulate the pathogenesis of HIT. hPF4 released from platelets predominantly bound to peri-injury endothelium and formed HIT antigenic complexes that were dissociated by heparin. In mice expressing both hPF4+ and human platelet IgG Fc receptor IIA (FcγRIIA), infusion of the HIT-like monoclonal antibody KKO increased fibrin and platelet deposition at sites of injury, followed immediately by antigen formation on proximate endothelial cells. After a few minutes, HIT antigen was detected within the thrombus itself at the interface between the platelet core and the surrounding shell. We observed similar results in the humanized, endothelialized microfluidic system. hPF4 and KKO selectively bound to photochemically injured endothelium at sites where surface glycocalyx was reduced. These studies support the concept that the perithrombus endothelium is the predominant site of HIT antigen assembly. This suggests that disrupting antigen formation along the endothelium or protecting the endothelium may provide a therapeutic opportunity to prevent thrombotic complications of HIT, while sparing systemic hemostatic pathways.
Authors
Vincent Hayes, Ian Johnston, Gowthami M. Arepally, Steven E. McKenzie, Douglas B. Cines, Lubica Rauova, Mortimer Poncz
×Abstract
Microvascular endothelial cells (ECs) are increasingly recognized as organ-specific gatekeepers of their microenvironment. Microvascular ECs instruct neighboring cells in their organ-specific vascular niches through angiocrine factors, which include secreted growth factors (angiokines), extracellular matrix molecules, and transmembrane proteins. However, the molecular regulators that drive organ-specific microvascular transcriptional programs and thereby regulate angiodiversity are largely elusive. In contrast to other ECs, which form a continuous cell layer, liver sinusoidal ECs (LSECs) constitute discontinuous, permeable microvessels. Here, we have shown that the transcription factor GATA4 controls murine LSEC specification and function. LSEC-restricted deletion of
Gata4 caused transformation of discontinuous liver sinusoids into continuous capillaries. Capillarization was characterized by ectopic basement membrane deposition, formation of a continuous EC layer, and increased expression of VE-cadherin. Correspondingly, ectopic expression of GATA4 in cultured continuous ECs mediated the downregulation of continuous EC-associated transcripts and upregulation of LSEC-associated genes. The switch from discontinuous LSECs to continuous ECs during embryogenesis caused liver hypoplasia, fibrosis, and impaired colonization by hematopoietic progenitor cells, resulting in anemia and embryonic lethality. Thus, GATA4 acts as master regulator of hepatic microvascular specification and acquisition of organ-specific vascular competence, which are indispensable for liver development. The data also establish an essential role of the hepatic microvasculature in embryonic hematopoiesis.Authors
Cyrill Géraud, Philipp-Sebastian Koch, Johanna Zierow, Kay Klapproth, Katrin Busch, Victor Olsavszky, Thomas Leibing, Alexandra Demory, Friederike Ulbrich, Miriam Diett, Sandhya Singh, Carsten Sticht, Katja Breitkopf-Heinlein, Karsten Richter, Sanna-Maria Karppinen, Taina Pihlajaniemi, Bernd Arnold, Hans-Reimer Rodewald, Hellmut G. Augustin, Kai Schledzewski, Sergij Goerdt
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