Abstract
Glioblastomas, which contain stem cell–like glioblastoma stem cells (GSCs), are universally lethal cancers. While neural stem cells (NSCs) are usually quiescent, single-cell studies suggest that proliferating glioblastoma cells reside in the GSC population. Interrogating in silico glioma databases for epigenetic regulators that correlate with cell cycle regulation, we identified the chromatin remodeler HELLS as a potential target in glioblastoma. GSCs preferentially expressed HELLS compared with their differentiated tumor progeny and nonmalignant brain cells. Targeting HELLS disrupted GSC proliferation, survival, and self-renewal with induction of replication stress and DNA damage. Investigating potential molecular mechanisms downstream of HELLS revealed that HELLS interacted with the core oncogenic transcription factors, E2F3 and MYC, to regulate gene expression critical to GSC proliferation and maintenance. Supporting the interaction, HELLS expression strongly correlated with targets of E2F3 and MYC transcriptional activity in glioblastoma patients. The potential clinical significance of HELLS was reinforced by improved survival of tumor-bearing mice upon targeting HELLS and poor prognosis of glioma patients with elevated HELLS expression. Collectively, targeting HELLS may permit the functional disruption of the relatively undruggable MYC and E2F3 transcription factors and serve as a novel therapeutic paradigm for glioblastoma.
Authors
Guoxin Zhang, Zhen Dong, Briana C. Prager, Leo J.K. Kim, Qiulian Wu, Ryan C. Gimple, Xiuxing Wang, Shideng Bao, Petra Hamerlik, Jeremy N. Rich
Abstract
Peripheral hyperinsulinemia resulting from subcutaneous insulin injection is associated with metabolic defects that include abnormal glucose metabolism. The first aim of this study was to quantify the impairments in liver and muscle glucose metabolism that occur when insulin is delivered via a peripheral vein compared to when it is given through its endogenous secretory route (the hepatic portal vein) in overnight-fasted conscious dogs. The second aim was to determine if peripheral delivery of a hepato-preferential insulin analog could restore the physiologic response to insulin that occurs under meal-feeding conditions. This study is the first to our knowledge to show that hepatic glucose uptake correlates with insulin’s direct effects on the liver under hyperinsulinemic-hyperglycemic conditions. In addition, glucose uptake was equally divided between the liver and muscle when insulin was infused into the portal vein, but when it was delivered into a peripheral vein the percentage of glucose taken up by muscle was 4-fold greater than that going to the liver, with liver glucose uptake being less than half of normal. These defects could not be corrected by adjusting the dose of peripheral insulin. On the other hand, hepatic and nonhepatic glucose metabolism could be fully normalized by a hepato-preferential insulin analog.
Authors
Dale S. Edgerton, Melanie Scott, Ben Farmer, Phillip E. Williams, Peter Madsen, Thomas Kjeldsen, Christian L. Brand, Christian Fledelius, Erica Nishimura, Alan D. Cherrington
Abstract
Hypertrophic cardiomyopathy (HCM) is triggered mainly by mutations in genes encoding sarcomeric proteins, but a significant proportion of patients lack a genetic diagnosis. We identified a potentially novel mutation in ryanodine receptor 2, RyR2-P1124L, in a patient from a genotype-negative HCM cohort. The aim of this study was to determine whether RyR2-P1124L triggers functional and structural alterations in isolated RyR2 channels and whole hearts. We found that P1124L induces significant conformational changes in the SPRY2 domain of RyR2. Recombinant RyR2-P1124L channels displayed a cytosolic loss-of-function phenotype, which contrasted with a higher sensitivity to luminal [Ca2+], indicating a luminal gain of function. Homozygous mice for RyR2-P1124L showed mild cardiac hypertrophy, similar to the human patient. This phenotype, evident at 1 year of age, was accompanied by an increase in the expression of calmodulin (CaM). P1124L mice also showed higher susceptibility to arrhythmia at 8 months of age, before the onset of hypertrophy. RyR2-P1124L has a distinct cytosolic loss-of-function and a luminal gain-of-function phenotype. This bifunctionally divergent behavior triggers arrhythmias and structural cardiac remodeling, and it involves overexpression of CaM as a potential hypertrophic mediator. This study is relevant to continue elucidating the possible causes of genotype-negative HCM and the role of RyR2 in cardiac hypertrophy.
Authors
Francisco J. Alvarado, J. Martijn Bos, Zhiguang Yuchi, Carmen R. Valdivia, Jonathan J. Hernández, Yan-Ting Zhao, Dawn S. Henderlong, Yan Chen, Talia R. Booher, Cherisse A. Marcou, Filip Van Petegem, Michael J. Ackerman, Héctor H. Valdivia
Abstract
The autoantigen-specific Tregs from pluripotent stem cells (PSCs), i.e., PSC-Tregs, have the ability to suppress autoimmunity. PSC-Tregs can be programmed to be tissue associated and to infiltrate into local inflamed tissues to suppress autoimmune responses after adoptive transfer. Nevertheless, the mechanisms by which the autoantigen-specific PSC-Tregs suppress the autoimmune response remain to be fully elucidated. In this study, we generated functional autoantigen-specific Tregs from the induced PSC (iPSCs), i.e., iPSC-Tregs, and investigated the underlying mechanisms of autoimmunity suppression by these Tregs in a type 1 diabetes (T1D) murine model. A double-Tg mouse model of T1D was established in F1 mice, in which the first generation of RIP-mOVA Tg mice that were crossed with OT-I T cell receptor (TCR) Tg mice was challenged with vaccinia viruses expressing OVA (VACV-OVA). We show that adoptive transfer of OVA-specific iPSC-Tregs greatly suppressed autoimmunity in the animal model and prevented the insulin-secreting pancreatic β cells from destruction. Further, we demonstrate that the adoptive transfer significantly reduced the expression of ICAM-1 in the diabetic pancreas and inhibited the migration of pathogenic CD8+ T cells and the production of the proinflammatory IFN-γ in the pancreas. These results indicate that the stem cell–derived tissue-associated Tregs can robustly accumulate in the diabetic pancreas, and, through downregulating the expression of ICAM-1 in the local inflamed tissues and inhibiting the production of proinflammatory cytokine IFN-γ, suppress the migration and activity of the pathogenic immune cells that cause T1D.
Authors
Mohammad Haque, Fengyang Lei, Xiaofang Xiong, Jugal Kishore Das, Xingcong Ren, Deyu Fang, Shahram Salek-Ardakani, Jin-Ming Yang, Jianxun Song
Abstract
Mechanisms leading to osteoporosis are incompletely understood. Genetic disorders with skeletal fragility provide insight into metabolic pathways contributing to bone strength. We evaluated 6 families with rare skeletal phenotypes and osteoporosis by next-generation sequencing. In all the families, we identified a heterozygous variant in SGMS2, a gene prominently expressed in cortical bone and encoding the plasma membrane–resident sphingomyelin synthase SMS2. Four unrelated families shared the same nonsense variant, c.148C>T (p.Arg50*), whereas the other families had a missense variant, c.185T>G (p.Ile62Ser) or c.191T>G (p.Met64Arg). Subjects with p.Arg50* presented with childhood-onset osteoporosis with or without cranial sclerosis. Patients with p.Ile62Ser or p.Met64Arg had a more severe presentation, with neonatal fractures, severe short stature, and spondylometaphyseal dysplasia. Several subjects had experienced peripheral facial nerve palsy or other neurological manifestations. Bone biopsies showed markedly altered bone material characteristics, including defective bone mineralization. Osteoclast formation and function in vitro was normal. While the p.Arg50* mutation yielded a catalytically inactive enzyme, p.Ile62Ser and p.Met64Arg each enhanced the rate of de novo sphingomyelin production by blocking export of a functional enzyme from the endoplasmic reticulum. SGMS2 pathogenic variants underlie a spectrum of skeletal conditions, ranging from isolated osteoporosis to complex skeletal dysplasia, suggesting a critical role for plasma membrane–bound sphingomyelin metabolism in skeletal homeostasis.
Authors
Minna Pekkinen, Paulien A. Terhal, Lorenzo D. Botto, Petra Henning, Riikka E. Mäkitie, Paul Roschger, Amrita Jain, Matthijs Kol, Matti A. Kjellberg, Eleftherios P. Paschalis, Koen van Gassen, Mary Murray, Pinar Bayrak-Toydemir, Maria K. Magnusson, Judith Jans, Mehran Kausar, John C. Carey, Pentti Somerharju, Ulf H. Lerner, Vesa M. Olkkonen, Klaus Klaushofer, Joost C.M. Holthuis, Outi Mäkitie
Abstract
Zika virus (ZIKV) infection during pregnancy causes significant adverse sequelae in the developing fetus, and results in long-term structural and neurologic defects. Most preventive and therapeutic efforts have focused on the development of vaccines, antivirals, and antibodies. The placental immunologic response to ZIKV, however, has been largely overlooked as a target for therapeutic intervention. The placental inflammatory response, specifically IL-1β secretion and signaling, is induced by ZIKV infection and represents an environmental factor that is known to increase the risk of perinatal developmental abnormalities. We show in a mouse model that maternally administrated IL-1 receptor antagonist (IRA; Kineret, or anakinra), following ZIKV exposure, can preserve placental function (by improving trophoblast invasion and placental vasculature), increase fetal viability, and reduce neurobehavioral deficits in the offspring. We further demonstrate that while ZIKV RNA is highly detectable in placentas, it is not correlated with fetal viability. Beyond its effects in the placenta, we show that IL-1 blockade may also directly decrease fetal neuroinflammation by mitigating fetal microglial activation in a dose-dependent manner. Our studies distinguish the role of placental inflammation during ZIKV-infected pregnancies, and demonstrate that maternal IRA may attenuate fetal neuroinflammation and improve perinatal outcomes.
Authors
Jun Lei, Meghan S. Vermillion, Bei Jia, Han Xie, Li Xie, Michael W. McLane, Jeanne S. Sheffield, Andrew Pekosz, Amanda Brown, Sabra L. Klein, Irina Burd
Abstract
Paraneoplastic neurological disorders result from an autoimmune response against neural self-antigens that are ectopically expressed in neoplastic cells. In paraneoplastic disorders associated to autoantibodies against intracellular proteins, such as paraneoplastic cerebellar degeneration (PCD), current data point to a major role of cell-mediated immunity. In an animal model, in which a neo–self-antigen was expressed in both Purkinje neurons and implanted breast tumor cells, immune checkpoint blockade led to complete tumor control at the expense of cerebellum infiltration by T cells and Purkinje neuron loss, thereby mimicking PCD. Here, we identify 2 potential therapeutic targets expressed by cerebellum-infiltrating T cells in this model, namely α4 integrin and IFN-γ. Mice with PCD were treated with anti-α4 integrin antibodies or neutralizing anti–IFN-γ antibodies at the onset of neurological signs. Although blocking α4 integrin had little or no impact on disease development, treatment using the anti–IFN-γ antibody led to almost complete protection from PCD. These findings strongly suggest that the production of IFN-γ by cerebellum-invading T cells plays a major role in Purkinje neuron death. Our successful preclinical use of neutralizing anti–IFN-γ antibody for the treatment of PCD offers a potentially new therapeutic opportunity for cancer patients at the onset of paraneoplastic neurological disorders.
Authors
Lidia Yshii, Béatrice Pignolet, Emilie Mauré, Mandy Pierau, Monika Brunner-Weinzierl, Oliver Hartley, Jan Bauer, Roland Liblau
Abstract
Actinic keratosis (AK) is a precancerous skin lesion that is common in HIV-positive patients. Without effective treatment, AKs can progress to squamous cell carcinoma. Ingenol mebutate, a PKC agonist, is a US Food and Drug Administration–approved (FDA-approved) topical treatment for AKs. It can induce reactivation of latent HIV transcription in CD4+ T cells both in vitro and ex vivo. Although PKC agonists are known to be potent inducers of HIV expression from latency, their effects in vivo are not known because of the concerns of toxicity. Therefore, we sought to determine the effects of topical ingenol mebutate gel on the HIV transcription profile in HIV-infected individuals with AKs, specifically in the setting of suppressive antiretroviral therapy (ART). We found that AKs cleared following topical application of ingenol mebutate and detected marginal changes in immune activation in the peripheral blood and in skin biopsies. An overall increase in the level of HIV transcription initiation, elongation, and complete transcription was detected only in skin biopsies after the treatment. Our data demonstrate that application of ingenol mebutate to AKs in ART-suppressed HIV-positive patients can effectively cure AKs as well as disrupt HIV latency in the skin tissue microenvironment in vivo without causing massive immune activation.
Authors
Guochun Jiang, Emanual Maverakis, Michelle Y. Cheng, Maher M. Elsheikh, Claire Deleage, Gema Méndez-Lagares, Michiko Shimoda, Steven A. Yukl, Dennis J. Hartigan-O’Connor, George R. Thompson III, Jacob D. Estes, Joseph K. Wong, Satya Dandekar
Abstract
Chronic tubulointerstitial injury impacts the prognosis of focal segmental glomerulosclerosis (FSGS). We found that the level of versican V1 was increased in tubular cells of FSGS patients. Tubular cell–derived versican V1 induced proliferation and collagen synthesis by activating the CD44/Smad3 pathway in fibroblasts. Both urine C3a and suPAR were increased and bound to the tubular cells in FSGS patients. C3a promoted the transcription of versican by activating the AKT/β-catenin pathway. C3aR knockout decreased the expression of versican in Adriamycin-treated (ADR-treated) mice. On the other hand, suPAR bound to integrin β6 and activated Rac1, which bound to SRp40 at the 5′ end of exon 7 in versican pre-mRNA. This binding inhibited the 3′-end splicing of intron 6 and the base-pair interactions between intron 6 and intron 8, leading to the formation of versican V1. Cotreatment with ADR and suPAR specifically increased the level of versican V1 in tubulointerstitial tissues and caused more obvious interstitial fibrosis in mice than treatment with only ADR. Altogether, our results show that C3a and suPAR drive versican V1 expression in tubular cells by promoting transcription and splicing, respectively, and the increases in tubular cell–derived versican V1 induce interstitial fibrosis by activating fibroblasts in FSGS.
Authors
Runhong Han, Shuai Hu, Weisong Qin, Jinsong Shi, Qin Hou, Xia Wang, Xiaodong Xu, Minchao Zhang, Caihong Zeng, Zhihong Liu, Hao Bao
Abstract
Antibody-mediated lymphoablation is used in solid organ and stem cell transplantation and autoimmunity. Using murine anti-thymocyte globulin (mATG) in a mouse model of heart transplantation, we previously reported that the homeostatic recovery of CD8+ T cells requires help from depletion-resistant memory CD4+ T cells delivered through CD40-expressing B cells. This study investigated the mechanisms by which B cells mediate CD8+ T cell proliferation in lymphopenic hosts. While CD8+ T cell recovery required MHC class I expression in the host, the reconstitution occurred independently of MHC class I, MHC class II, or CD80/CD86 expression on B cells. mATG lymphoablation upregulated the B cell expression of several cytokine genes, including IL-15 and IL-27, in a CD4-dependent manner. Neither treatment with anti-CD122 mAb nor the use of IL-15Rα–/– recipients altered CD8+ T cell recovery after mATG treatment, indicating that IL-15 may be dispensable for T cell proliferation in our model. Instead, IL-27 neutralization or the use of IL-27Rα–/– CD8+ T cells inhibited CD8+ T cell proliferation and altered the phenotype and cytokine profile of reconstituted CD8+ T cells. Our findings uncover what we believe is a novel role of IL-27 in lymphopenia-induced CD8+ T cell proliferation and suggest that targeting B cell–derived cytokines may increase the efficacy of lymphoablation and improve transplant outcomes.
Authors
Katayoun Ayasoufi, Daniel B. Zwick, Ran Fan, Suheyla Hasgur, Michael Nicosia, Victoria Gorbacheva, Karen S. Keslar, Booki Min, Robert L. Fairchild, Anna Valujskikh
No posts were found with this tag.
