Glinton et al. report that cardiac VEGFC derived from macrophages after efferocytosis ameliorate injury and inflammation after myocardial infarction. The cover image shows CD68-positive macrophages (red) and LYVE1-positive lymphatic endothelial cells (green) in murine cardiac sections after coronary artery ligation.
The mechanisms that explain mitochondrial dysfunction in aging and healthspan continue to be studied, but one element has been unexplored: microproteins. Small open reading frames in circular mitochondria DNA can encode multiple microproteins, called mitochondria-derived peptides (MDPs). Currently, eight MDPs have been published: humanin, MOTS-c, and SHLPs 1–6. This Review describes recent advances in microprotein discovery with a focus on MDPs. It discusses what is currently known about MDPs in aging and how this new understanding could add to the way we understand age-related diseases including type 2 diabetes, cancer, and neurodegenerative diseases at the genomic, proteomic, and drug-development levels.
Brendan Miller, Su-Jeong Kim, Hiroshi Kumagai, Kelvin Yen, Pinchas Cohen
Cardiovascular disease (CVD) accounts for almost half of all deaths related to non-communicable disease worldwide, making it the single largest global cause of mortality. Although the risk factors for coronary artery disease — the most common cause of CVD — are well known and include hypertension, high cholesterol, age, and genetics, CVDs are now recognized as chronic inflammatory conditions. Arterial blockages, known as atherosclerosis, develop due to excess cholesterol accumulating within the arterial wall, creating a perpetually inflammatory state. The normally quiescent intimal layer of the vessel wall becomes laden with inflammatory cells, which alters the surrounding endothelial, smooth muscle, and extracellular matrix components to propagate disease. Macrophages, which can be either tissue resident or monocyte derived, are a key player in atherosclerotic disease progression and regression, and the understanding of their functions and origins continues to evolve with the use of deep phenotyping methodologies. This Review outlines how macrophages interact with each layer of the developing atherosclerotic plaque and discusses new concepts that are challenging our previous views on how macrophages function and our evolving understanding of the contribution of macrophages to disease.
Leah I. Susser, Katey J. Rayner
Autosomal dominant disorders present unique challenges, as therapeutics must often distinguish between healthy and diseased alleles while maintaining high efficiency, specificity, and safety. For this task, CRISPR/Cas remains particularly promising. Various CRISPR/Cas systems, like homology-directed repair, base editors, and prime editors, have been demonstrated to selectively edit mutant alleles either by incorporating these mutations into sgRNA sequences (near the protospacer-adjacent motif [“near the PAM”]) or by targeting a novel PAM generated by the mutation (“in the PAM”). However, these probability-based designs are not always assured, necessitating generalized, mutation-agnostic strategies like ablate-and-replace and single-nucleotide polymorphism editing. Here, we detail recent advancements in CRISPR therapeutics to treat a wide range of autosomal dominant disorders and discuss how they are altering the landscape for future therapies.
Salvatore Marco Caruso, Peter M.J. Quinn, Bruna Lopes da Costa, Stephen H. Tsang
Cardiac repair following ischemic injury is indispensable for survival and requires a coordinated cellular response involving the mobilization of immune cells from the secondary lymphoid organs to the site of damage. Efferocytosis, the engulfment of cell debris and dying cells by innate immune cells, along with lymphangiogenesis, the formation of new lymphatic vessels, are emerging as central to the cardiac healing response. In this issue of the JCI, Glinton et al. used state-of-the-art approaches to demonstrate that efferocytosis induced vascular endothelial growth factor C (VEGFC) in myeloid cells and stimulated lymphangiogenesis and cardiac repair. These findings provide impactful mechanistic information that can be leveraged to therapeutically target pathways in cardiac repair and ischemic heart failure.
Patricia A. D’Amore, Pilar Alcaide
Brown adipose tissue (BAT) dissipates energy in the form of heat and functions as a metabolic sink for lipids, glucose, and branched-chain amino acids. Enhanced BAT thermogenesis is thought to tightly couple with beneficial energy metabolism. However, in this issue of the JCI, Huang et al. report a mouse model in which BAT thermogenesis was impaired, yet systemic glucose and lipid homeostasis were improved, on a high-fat diet compared with what occurred in control mice. The authors showed that BAT-specific deletion of mitochondrial thioredoxin-2 (TRX2) impaired adaptive thermogenesis through elevated mitochondrial reactive oxygen species (ROS) and cytosolic efflux of mitochondrial DNA. On the other hand, TRX2 loss enhanced lipid uptake in the BAT and protected mice from obesity, hypertriglyceridemia, and insulin resistance. This study provides a unique model in which BAT does not require thermogenesis per se to function as a lipid sink that leads to metabolic benefits in vivo.
Jin-Seon Yook, Shingo Kajimura
T follicular helper (Tfh) cells are a subset of CD4+ T cells that are essential in the pathogenesis of systemic lupus erythematosus (SLE). Notably, iron is required for activated CD4+ T lymphocytes to sustain high proliferation and metabolism. In this issue of the JCI, Gao et al. showed that CD4+ T cells from patients with SLE accumulated iron, augmenting their differentiation into Tfh cells and correlating with disease activity. Using human cells and murine models, the authors demonstrated that miR-21 was overexpressed in lupus T cells and inhibited 3-hydroxybutyrate dehydrogenase-2 (BDH2). The subsequent loss of BDH2 drove labile iron to accumulate in the cytoplasm and promoted TET enzyme activity, BCL6 gene demethylation, and Tfh cell differentiation. This work identifies a role for iron in CD4+ T cell biology and the development of pathogenic effectors in SLE. We await future investigations that could determine whether modulating iron levels could regulate Tfh cells in human health and disease.
Yogesh Scindia, Borna Mehrad, Laurence Morel
Tumor-associated hypoxia plays an important role in carcinogenesis and metastasis. The expression, activation, and stabilization of hypoxia-inducible transcription factors (HIFs) support malignant cell survival, proliferation, plasticity, and motility. Hypoxia also upregulates the expression of programmed cell death ligand 1 (PD-L1) in malignant and immune regulatory cells. Therefore, the combination of HIF inhibitors and checkpoint inhibitors (CPIs) is promising for boosting antitumor immunity and diminishing malignant cell plasticity and therapy resistance. In this issue of the JCI, Salman et al. report the development of a specific agent that inhibited HIF-1/2–mediated gene expression in tumor cells and suppressed tumor growth. Bailey, Liu, et al. in this issue demonstrate that targeting HIF-1α abrogated PD-L1–mediated immune evasion by suppressing PD-L1 expression on malignant and myeloid regulatory cells, causing tumor rejection. These findings suggest that targeting the HIF/PD-L1 axis with specific HIF inhibitors should improve the safety and efficacy of CPIs for cancer therapy.
Michael R. Shurin, Viktor Umansky
Clearance of dying cells by efferocytosis is necessary for cardiac repair after myocardial infarction (MI). Recent reports have suggested a protective role for vascular endothelial growth factor C (VEGFC) during acute cardiac lymphangiogenesis after MI. Here, we report that defective efferocytosis by macrophages after experimental MI led to a reduction in cardiac lymphangiogenesis and Vegfc expression. Cell-intrinsic evidence for efferocytic induction of Vegfc was revealed after adding apoptotic cells to cultured primary macrophages, which subsequently triggered Vegfc transcription and VEGFC secretion. Similarly, cardiac macrophages elevated Vegfc expression levels after MI, and mice deficient for myeloid Vegfc exhibited impaired ventricular contractility, adverse tissue remodeling, and reduced lymphangiogenesis. These results were observed in mouse models of permanent coronary occlusion and clinically relevant ischemia and reperfusion. Interestingly, myeloid Vegfc deficiency also led to increases in acute infarct size, prior to the amplitude of the acute cardiac lymphangiogenesis response. RNA-Seq and cardiac flow cytometry revealed that myeloid Vegfc deficiency was also characterized by a defective inflammatory response, and macrophage-produced VEGFC was directly effective at suppressing proinflammatory macrophage activation. Taken together, our findings indicate that cardiac macrophages promote healing through the promotion of myocardial lymphangiogenesis and the suppression of inflammatory cytokines.
Kristofor E. Glinton, Wanshu Ma, Connor Lantz, Lubov S. Grigoryeva, Matthew DeBerge, Xiaolei Liu, Maria Febbraio, Mark Kahn, Guillermo Oliver, Edward B. Thorp
The glomerular filtration barrier (GFB) produces primary urine and is composed of a fenestrated endothelium, a glomerular basement membrane (GBM), podocytes, and a slit diaphragm. Impairment of the GFB leads to albuminuria and microhematuria. The GBM is generated via secreted proteins from both endothelial cells and podocytes and is supposed to majorly contribute to filtration selectivity. While genetic mutations or variations of GBM components have been recently proposed to be a common cause of glomerular diseases, pathways modifying and stabilizing the GBM remain incompletely understood. Here, we identified prolyl 3-hydroxylase 2 (P3H2) as a regulator of the GBM in an a cohort of patients with albuminuria. P3H2 hydroxylates the 3′ of prolines in collagen IV subchains in the endoplasmic reticulum. Characterization of a P3h2ΔPod mouse line revealed that the absence of P3H2 protein in podocytes induced a thin basement membrane nephropathy (TBMN) phenotype with a thinner GBM than that in WT mice and the development of microhematuria and microalbuminuria over time. Mechanistically, differential quantitative proteomics of the GBM identified a significant decrease in the abundance of collagen IV subchains and their interaction partners in P3h2ΔPod mice. To our knowledge, P3H2 protein is the first identified GBM modifier, and loss or mutation of P3H2 causes TBMN and focal segmental glomerulosclerosis in mice and humans.
Hande Aypek, Christoph Krisp, Shun Lu, Shuya Liu, Dominik Kylies, Oliver Kretz, Guochao Wu, Manuela Moritz, Kerstin Amann, Kerstin Benz, Ping Tong, Zheng-mao Hu, Sulaiman M. Alsulaiman, Arif O. Khan, Maik Grohmann, Timo Wagner, Janina Müller-Deile, Hartmut Schlüter, Victor G. Puelles, Carsten Bergmann, Tobias B. Huber, Florian Grahammer
Brown adipose tissue (BAT), a crucial heat-generating organ, regulates whole-body energy metabolism by mediating thermogenesis. BAT inflammation is implicated in the pathogenesis of mitochondrial dysfunction and impaired thermogenesis. However, the link between BAT inflammation and systematic metabolism remains unclear. Herein, we use mice with BAT deficiency of thioredoxin-2 (TRX2), a protein that scavenges mitochondrial reactive oxygen species (ROS), to evaluate the impact of BAT inflammation on metabolism and thermogenesis and its underlying mechanism. Our results show that BAT-specific TRX2 ablation improves systematic metabolic performance via enhancing lipid uptake, which protects mice from diet-induced obesity, hypertriglyceridemia, and insulin resistance. TRX2 deficiency impairs adaptive thermogenesis by suppressing fatty acid oxidation. Mechanistically, loss of TRX2 induces excessive mitochondrial ROS, mitochondrial integrity disruption, and cytosolic release of mitochondrial DNA, which in turn activate aberrant innate immune responses in BAT, including the cGAS/STING and the NLRP3 inflammasome pathways. We identify NLRP3 as a key converging point, as its inhibition reverses both the thermogenesis defect and the metabolic benefits seen under nutrient overload in BAT-specific Trx2-deficient mice. In conclusion, we identify TRX2 as a critical hub integrating oxidative stress, inflammation, and lipid metabolism in BAT, uncovering an adaptive mechanism underlying the link between BAT inflammation and systematic metabolism.
Yanrui Huang, Jenny H. Zhou, Haifeng Zhang, Alberto Canfran-Duque, Abhishek K. Singh, Rachel J. Perry, Gerald I. Shulman, Carlos Fernandez-Hernando, Wang Min
People living with HIV (PLWH) who are immune nonresponders (INRs) are at greater risk of comorbidity and mortality than are immune responders (IRs) who restore their CD4+ T cell count after antiretroviral therapy (ART). INRs have low CD4+ T cell counts (<350 c/μL), heightened systemic inflammation, and increased CD4+ T cell cycling (Ki67+). Here, we report the findings that memory CD4+ T cells and plasma samples of INRs from several cohorts are enriched in gut-derived bacterial solutes p-cresol sulfate (PCS) and indoxyl sulfate (IS) that both negatively correlated with CD4+ T cell counts. In vitro PCS or IS blocked CD4+ T cell proliferation, induced apoptosis, and diminished the expression of mitochondrial proteins. Electron microscopy imaging revealed perturbations of mitochondrial networks similar to those found in INRs following incubation of healthy memory CD4+ T cells with PCS. Using bacterial 16S rDNA, INR stool samples were found enriched in proteolytic bacterial genera that metabolize tyrosine and phenylalanine to produce PCS. We propose that toxic solutes from the gut bacterial flora may impair CD4+ T cell recovery during ART and may contribute to CD4+ T cell lymphopenia characteristic of INRs.
Brian Ferrari, Amanda Cabral Da Silva, Ken H. Liu, Evgeniya V. Saidakova, Larisa B. Korolevskaya, Konstantin V. Shmagel, Carey Shive, Gabriela Pacheco Sanchez, Mauricio Retuerto, Ashish Arunkumar Sharma, Khader Ghneim, Laura Noel-Romas, Benigno Rodriguez, Mahmoud A. Ghannoum, Peter P. Hunt, Steven G. Deeks, Adam D. Burgener, Dean P. Jones, Mirela A. Dobre, Vincent C. Marconi, Rafick-Pierre Sekaly, Souheil-Antoine Younes
A combination of anti–CTLA-4 plus anti–PD-1/PD-L1 is the most effective cancer immunotherapy but causes high incidence of immune-related adverse events (irAEs). Here we report that targeting of HIF-1α suppressed PD-L1 expression on tumor cells and tumor-infiltrating myeloid cells, but unexpectedly induced PD-L1 in normal tissues by an IFN-γ–dependent mechanism. Targeting the HIF-1α/PD-L1 axis in tumor cells reactivated tumor-infiltrating lymphocytes and caused tumor rejection. The HIF-1α inhibitor echinomycin potentiated the cancer immunotherapeutic effects of anti–CTLA-4 therapy, with efficacy comparable to that of anti–CTLA-4 plus anti–PD-1 antibodies. However, while anti–PD-1 exacerbated irAEs triggered by ipilimumab, echinomycin protected mice against irAEs by increasing PD-L1 levels in normal tissues. Our data suggest that targeting HIF-1α fortifies the immune tolerance function of the PD-1/PD-L1 checkpoint in normal tissues but abrogates its immune evasion function in the tumor microenvironment to achieve safer and more effective immunotherapy.
Christopher M. Bailey, Yan Liu, Mingyue Liu, Xuexiang Du, Martin Devenport, Pan Zheng, Yang Liu, Yin Wang
The loss function of cerebral cavernous malformation (CCM) genes leads to most CCM lesions characterized by enlarged leaking vascular lesions in the brain. Although we previously showed that NOGOB receptor (NGBR) knockout in endothelial cells (ECs) results in cerebrovascular lesions in the mouse embryo, the molecular mechanism by which NGBR regulates CCM1/2 expression has not been elucidated. Here, we show that genetic depletion of Ngbr in ECs at both postnatal and adult stages results in CCM1/2 expression deficiency and cerebrovascular lesions such as enlarged vessels, blood-brain-barrier hyperpermeability, and cerebral hemorrhage. To reveal the molecular mechanism, we used RNA-sequencing analysis to examine changes in the transcriptome. Surprisingly, we found that the acetyltransferase HBO1 and histone acetylation were downregulated in NGBR-deficient ECs. The mechanistic studies elucidated that NGBR is required for maintaining the expression of CCM1/2 in ECs via HBO1-mediated histone acetylation. ChIP-qPCR data further demonstrated that loss of NGBR impairs the binding of HBO1 and acetylated histone H4K5 and H4K12 on the promotor of the CCM1 and CCM2 genes. Our findings on epigenetic regulation of CCM1 and CCM2 that is modulated by NGBR and HBO1-mediated histone H4 acetylation provide a perspective on the pathogenesis of sporadic CCMs.
Zhi Fang, Xiaoran Sun, Xiang Wang, Ji Ma, Thomas Palaia, Ujala Rana, Benjamin Miao, Louis Ragolia, Wenquan Hu, Qing Robert Miao
The trace element iron affects immune responses and vaccination, but knowledge of its role in autoimmune diseases is limited. Expansion of pathogenic T cells, especially T follicular helper (Tfh) cells, has great significance to systemic lupus erythematosus (SLE) pathogenesis. Here, we show an important role of iron in regulation of pathogenic T cell differentiation in SLE. We found that iron overload promoted Tfh cell expansion, proinflammatory cytokine secretion, and autoantibody production in lupus-prone mice. Mice treated with a high-iron diet exhibited an increased proportion of Tfh cell and antigen-specific GC response. Iron supplementation contributed to Tfh cell differentiation. In contrast, iron chelation inhibited Tfh cell differentiation. We demonstrated that the miR-21/BDH2 axis drove iron accumulation during Tfh cell differentiation and further promoted Fe2+-dependent TET enzyme activity and BCL6 gene demethylation. Thus, maintaining iron homeostasis might be critical for eliminating pathogenic Th cells and might help improve the management of patients with SLE.
Xiaofei Gao, Yang Song, Jiali Wu, Shuang Lu, Xiaoli Min, Limin Liu, Longyuan Hu, Meiling Zheng, Pei Du, Yaqin Yu, Hai Long, Haijing Wu, Sujie Jia, Di Yu, Qianjin Lu, Ming Zhao
As blood transitions from steady laminar flow (S-flow) in healthy arteries to disturbed flow (D-flow) in aneurysmal arteries, platelets are subjected to external forces. Biomechanical platelet activation is incompletely understood and is a potential mechanism behind antiplatelet medication resistance. Although it has been demonstrated that antiplatelet drugs suppress the growth of abdominal aortic aneurysms (AAA) in patients, we found that a certain degree of platelet reactivity persisted in spite of aspirin therapy, urging us to consider additional antiplatelet therapeutic targets. Transcriptomic profiling of platelets from patients with AAA revealed upregulation of a signal transduction pathway common to olfactory receptors, and this was explored as a mediator of AAA progression. Healthy platelets subjected to D-flow ex vivo, platelets from patients with AAA, and platelets in murine models of AAA demonstrated increased membrane olfactory receptor 2L13 (OR2L13) expression. A drug screen identified a molecule activating platelet OR2L13, which limited both biochemical and biomechanical platelet activation as well as AAA growth. This observation was further supported by selective deletion of the OR2L13 ortholog in a murine model of AAA that accelerated aortic aneurysm growth and rupture. These studies revealed that olfactory receptors regulate platelet activation in AAA and aneurysmal progression through platelet-derived mediators of aortic remodeling.
Craig N. Morrell, Doran Mix, Anu Aggarwal, Rohan Bhandari, Matthew Godwin, Phillip Owens III, Sean P. Lyden, Adam Doyle, Krystin Krauel, Matthew T. Rondina, Amy Mohan, Charles J. Lowenstein, Sharon Shim, Shaun Stauffer, Vara Prasad Josyula, Sara K. Ture, David I. Yule, Larry E. Wagner III, John M. Ashton, Ayman Elbadawi, Scott J. Cameron
Activated SUMOylation is a hallmark of cancer. Starting from a targeted screening for SUMO-regulated immune evasion mechanisms, we identified an evolutionarily conserved function of activated SUMOylation, which attenuated the immunogenicity of tumor cells. Activated SUMOylation allowed cancer cells to evade CD8+ T cell–mediated immunosurveillance by suppressing the MHC class I (MHC-I) antigen-processing and presentation machinery (APM). Loss of the MHC-I APM is a frequent cause of resistance to cancer immunotherapies, and the pharmacological inhibition of SUMOylation (SUMOi) resulted in reduced activity of the transcriptional repressor scaffold attachment factor B (SAFB) and induction of the MHC-I APM. Consequently, SUMOi enhanced the presentation of antigens and the susceptibility of tumor cells to CD8+ T cell–mediated killing. Importantly, SUMOi also triggered the activation of CD8+ T cells and thereby drove a feed-forward loop amplifying the specific antitumor immune response. In summary, we showed that activated SUMOylation allowed tumor cells to evade antitumor immunosurveillance, and we have expanded the understanding of SUMOi as a rational therapeutic strategy for enhancing the efficacy of cancer immunotherapies.
Uta M. Demel, Marlitt Böger, Schayan Yousefian, Corinna Grunert, Le Zhang, Paul W. Hotz, Adrian Gottschlich, Hazal Köse, Konstandina Isaakidis, Dominik Vonficht, Florian Grünschläger, Elena Rohleder, Kristina Wagner, Judith Dönig, Veronika Igl, Bernadette Brzezicha, Francis Baumgartner, Stefan Habringer, Jens Löber, Björn Chapuy, Carl Weidinger, Sebastian Kobold, Simon Haas, Antonia B. Busse, Stefan Müller, Matthias Wirth, Markus Schick, Ulrich Keller
Obesity-associated complications are causing increasing morbidity and mortality worldwide. Expansion of adipose tissue in obesity leads to a state of low-grade chronic inflammation and dysregulated metabolism, resulting in insulin resistance and metabolic syndrome. Adipose tissue macrophages (ATMs) accumulate in obesity and are a source of proinflammatory cytokines that further aggravate adipocyte dysfunction. Macrophages are rich sources of cyclooxygenase (COX), the rate limiting enzyme for prostaglandin E2 (PGE2) production. When mice were fed a high-fat diet (HFD), ATMs increased expression of COX-2. Selective myeloid cell COX-2 deletion resulted in increased monocyte recruitment and proliferation of ATMs, leading to increased proinflammatory ATMs with decreased phagocytic ability. There were increased weight gain and adiposity, decreased peripheral insulin sensitivity and glucose utilization, increased adipose tissue inflammation and fibrosis, and abnormal adipose tissue angiogenesis. HFD pair-feeding led to similar increases in body weight, but mice with selective myeloid cell COX-2 still exhibited decreased peripheral insulin sensitivity and glucose utilization. Selective myeloid deletion of the macrophage PGE2 receptor subtype, EP4, produced a similar phenotype, and a selective EP4 agonist ameliorated the metabolic abnormalities seen with ATM COX-2 deletion. Therefore, these studies demonstrated that an ATM COX-2/PGE2/EP4 axis plays an important role in inhibiting adipose tissue dysfunction.
Yu Pan, Shirong Cao, Jiaqi Tang, Juan P. Arroyo, Andrew S. Terker, Yinqiu Wang, Aolei Niu, Xiaofeng Fan, Suwan Wang, Yahua Zhang, Ming Jiang, David H. Wasserman, Ming-Zhi Zhang, Raymond C. Harris
T cell immunoglobulin mucin domain-containing protein 3 (Tim-3) negatively regulates innate and adaptive immunity in cancer. To identify the mechanisms of Tim-3 in cancer immunity, we evaluated the effects of Tim-3 blockade in human and mouse melanoma. Here, we show that human programmed cell death 1–positive (PD-1+) Tim-3+CD8+ tumor-infiltrating lymphocytes (TILs) upregulate phosphatidylserine (PS), a receptor for Tim-3, and acquire cell surface myeloid markers from antigen-presenting cells (APCs) through transfer of membrane fragments called trogocytosis. Tim-3 blockade acted on Tim-3+ APCs in a PS-dependent fashion to disrupt the trogocytosis of activated tumor antigen–specific CD8+ T cells and PD-1+Tim-3+ CD8+ TILs isolated from patients with melanoma. Tim-3 and PD-1 blockades cooperated to disrupt trogocytosis of CD8+ TILs in 2 melanoma mouse models, decreasing tumor burden and prolonging survival. Deleting Tim-3 in dendritic cells but not in CD8+ T cells impeded the trogocytosis of CD8+ TILs in vivo. Trogocytosed CD8+ T cells presented tumor peptide–major histocompatibility complexes and became the target of fratricide T cell killing, which was reversed by Tim-3 blockade. Our findings have uncovered a mechanism Tim-3 uses to limit antitumor immunity.
Ornella Pagliano, Robert M. Morrison, Joe-Marc Chauvin, Hridesh Banerjee, Diwakar Davar, Quanquan Ding, Tokiyoshi Tanegashima, Wentao Gao, Saranya R. Chakka, Richelle DeBlasio, Ava Lowin, Kevin Kara, Mignane Ka, Bochra Zidi, Rada Amin, Itay Raphael, Shuowen Zhang, Simon C. Watkins, Cindy Sander, John M. Kirkwood, Marcus Bosenberg, Ana C. Anderson, Vijay K. Kuchroo, Lawrence P. Kane, Alan J. Korman, Arvind Rajpal, Sean M. West, Minhua Han, Christine Bee, Xiaodi Deng, Xiao Min Schebye, Pavel Strop, Hassane M. Zarour
The relevance of molecular mechanisms governing mitochondrial proteostasis to the differentiation and function of hematopoietic and immune cells is largely elusive. Through dissection of the network of proteins related to HCLS1-associated protein X-1, we defined a potentially novel functional CLPB/HAX1/(PRKD2)/HSP27 axis with critical importance for the differentiation of neutrophil granulocytes and, thus, elucidated molecular and metabolic mechanisms underlying congenital neutropenia in patients with HAX1 deficiency as well as bi- and monoallelic mutations in CLPB. As shown by stable isotope labeling by amino acids in cell culture (SILAC) proteomics, CLPB and HAX1 control the balance of mitochondrial protein synthesis and persistence crucial for proper mitochondrial function. Impaired mitochondrial protein dynamics are associated with decreased abundance of the serine-threonine kinase PRKD2 and HSP27 phosphorylated on serines 78 and 82. Cellular defects in HAX1–/– cells can be functionally reconstituted by HSP27. Thus, mitochondrial proteostasis emerges as a critical molecular and metabolic mechanism governing the differentiation and function of neutrophil granulocytes.
Yanxin Fan, Marta Murgia, Monika I. Linder, Yoko Mizoguchi, Cong Wang, Marcin Łyszkiewicz, Natalia Ziȩtara, Yanshan Liu, Stephanie Frenz, Gabriela Sciuccati, Armando Partida-Gaytan, Zahra Alizadeh, Nima Rezaei, Peter Rehling, Sven Dennerlein, Matthias Mann, Christoph Klein
The synthesis of serine from glucose is a key metabolic pathway supporting cellular proliferation in healthy and malignant cells. Despite this, the role that this aspect of metabolism plays in germinal center biology and pathology is not known. Here, we performed a comprehensive characterization of the role of the serine synthesis pathway in germinal center B cells and lymphomas derived from these cells. We demonstrate that upregulation of a functional serine synthesis pathway is a metabolic hallmark of B cell activation and the germinal center reaction. Inhibition of phosphoglycerate dehydrogenase (PHGDH), the first and rate-limiting enzyme in this pathway, led to defective germinal formation and impaired high-affinity antibody production. In addition, overexpression of enzymes involved in serine synthesis was a characteristic of germinal center B cell–derived lymphomas, with high levels of expression being predictive of reduced overall survival in diffuse large B cell lymphoma. Inhibition of PHGDH induced apoptosis in lymphoma cells, reducing disease progression. These findings establish PHGDH as a critical player in humoral immunity and a clinically relevant target in lymphoma.
Annalisa D’Avola, Nathalie Legrave, Mylène Tajan, Probir Chakravarty, Ryan L. Shearer, Hamish W. King, Katarina Kluckova, Eric C. Cheung, Andrew J. Clear, Arief S. Gunawan, Lingling Zhang, Louisa K. James, James I. MacRae, John G. Gribben, Dinis P. Calado, Karen H. Vousden, John C. Riches
Pericyte-mediated capillary constriction decreases cerebral blood flow in stroke after an occluded artery is unblocked. The determinants of pericyte tone are poorly understood. We show that a small rise in cytoplasmic Ca2+ concentration ([Ca2+]i) in pericytes activated chloride efflux through the Ca2+-gated anion channel TMEM16A, thus depolarizing the cell and opening voltage-gated calcium channels. This mechanism strongly amplified the pericyte [Ca2+]i rise and capillary constriction evoked by contractile agonists and ischemia. In a rodent stroke model, TMEM16A inhibition slowed the ischemia-evoked pericyte [Ca2+]i rise, capillary constriction, and pericyte death; reduced neutrophil stalling; and improved cerebrovascular reperfusion. Genetic analysis implicated altered TMEM16A expression in poor patient recovery from ischemic stroke. Thus, pericyte TMEM16A is a crucial regulator of cerebral capillary function and a potential therapeutic target for stroke and possibly other disorders of impaired microvascular flow, such as Alzheimer’s disease and vascular dementia.
Nils Korte, Zeki Ilkan, Claire L. Pearson, Thomas Pfeiffer, Prabhav Singhal, Jason R. Rock, Huma Sethi, Dipender Gill, David Attwell, Paolo Tammaro
The striatin-interacting phosphatase and kinase (STRIPAK) complexes integrate extracellular stimuli that result in intracellular activities. Previously, we discovered that STRIPAK is a key machinery responsible for loss of the Hippo tumor suppressor signal in cancer. Here, we identified the Hippo-STRIPAK complex as an essential player in the control of DNA double-stranded break (DSB) repair and genomic stability. Specifically, we found that the mammalian STE20-like protein kinases 1 and 2 (MST1/2), independent of classical Hippo signaling, directly phosphorylated zinc finger MYND type–containing 8 (ZMYND8) and hence resulted in the suppression of DNA repair in the nucleus. In response to genotoxic stress, the cyclic GMP-AMP synthase/stimulator of IFN genes (cGAS/STING) pathway was determined to relay nuclear DNA damage signals to the dynamic assembly of Hippo-STRIPAK via TANK-binding kinase 1–induced (TBK1-induced) structural stabilization of the suppressor of IKBKE 1– sarcolemma membrane–associated protein (SIKE1-SLMAP) arm. As such, we found that STRIPAK-mediated MST1/2 inactivation increased the DSB repair capacity of cancer cells and endowed these cells with resistance to radio- and chemotherapy and poly(ADP-ribose)polymerase (PARP) inhibition. Importantly, targeting the STRIPAK assembly with each of 3 distinct peptide inhibitors efficiently recovered the kinase activity of MST1/2 to suppress DNA repair and resensitize cancer cells to PARP inhibitors in both animal- and patient-derived tumor models. Overall, our findings not only uncover what we believe to be a previously unrecognized role for STRIPAK in modulating DSB repair but also provide translational implications of cotargeting STRIPAK and PARP for a new type of synthetic lethality anticancer therapy.
Liwei An, Zhifa Cao, Pingping Nie, Hui Zhang, Zhenzhu Tong, Fan Chen, Yang Tang, Yi Han, Wenjia Wang, Zhangting Zhao, Qingya Zhao, Yuqin Yang, Yuanzhi Xu, Gemin Fang, Lei Shi, Huixiong Xu, Haiqing Ma, Shi Jiao, Zhaocai Zhou
Many neurodegenerative disorders are caused by abnormal accumulation of misfolded proteins. In spinocerebellar ataxia type 1 (SCA1), accumulation of polyglutamine-expanded (polyQ-expanded) ataxin-1 (ATXN1) causes neuronal toxicity. Lowering total ATXN1, especially the polyQ-expanded form, alleviates disease phenotypes in mice, but the molecular mechanism by which the mutant ATXN1 is specifically modulated is not understood. Here, we identified 22 mutant ATXN1 regulators by performing a cross-species screen of 7787 and 2144 genes in human cells and Drosophila eyes, respectively. Among them, transglutaminase 5 (TG5) preferentially regulated mutant ATXN1 over the WT protein. TG enzymes catalyzed cross-linking of ATXN1 in a polyQ-length–dependent manner, thereby preferentially modulating mutant ATXN1 stability and oligomerization. Perturbing Tg in Drosophila SCA1 models modulated mutant ATXN1 toxicity. Moreover, TG5 was enriched in the nuclei of SCA1-affected neurons and colocalized with nuclear ATXN1 inclusions in brain tissue from patients with SCA1. Our work provides a molecular insight into SCA1 pathogenesis and an opportunity for allele-specific targeting for neurodegenerative disorders.
Won-Seok Lee, Ismael Al-Ramahi, Hyun-Hwan Jeong, Youjin Jang, Tao Lin, Carolyn J. Adamski, Laura A. Lavery, Smruti Rath, Ronald Richman, Vitaliy V. Bondar, Elizabeth Alcala, Jean-Pierre Revelli, Harry T. Orr, Zhandong Liu, Juan Botas, Huda Y. Zoghbi
Hepatocellular carcinoma (HCC) is a major cause of cancer mortality worldwide and available therapies, including immunotherapies, are ineffective for many patients. HCC is characterized by intratumoral hypoxia, and increased expression of hypoxia-inducible factor 1α (HIF-1α) in diagnostic biopsies is associated with patient mortality. Here we report the development of 32-134D, a low-molecular-weight compound that effectively inhibits gene expression mediated by HIF-1 and HIF-2 in HCC cells, and blocks human and mouse HCC tumor growth. In immunocompetent mice bearing Hepa1-6 HCC tumors, addition of 32-134D to anti-PD1 therapy increased the rate of tumor eradication from 25% to 67%. Treated mice showed no changes in appearance, behavior, body weight, hemoglobin, or hematocrit. Compound 32-134D altered the expression of a large battery of genes encoding proteins that mediate angiogenesis, glycolytic metabolism, and responses to innate and adaptive immunity. This altered gene expression led to significant changes in the tumor immune microenvironment, including a decreased percentage of tumor-associated macrophages and myeloid-derived suppressor cells, which mediate immune evasion, and an increased percentage of CD8+ T cells and natural killer cells, which mediate antitumor immunity. Taken together, these preclinical findings suggest that combining 32-134D with immune checkpoint blockade may represent a breakthrough therapy for HCC.
Shaima Salman, David J. Meyers, Elizabeth E. Wicks, Sophia N. Lee, Emmanuel Datan, Aline M. Thomas, Nicole M. Anders, Yousang Hwang, Yajing Lyu, Yongkang Yang, Walter Jackson III, Dominic Dordai, Michelle A. Rudek, Gregg L. Semenza
Replication of SARS-CoV-2 in the human population is defined by distributions of mutants that are present at different frequencies within the infected host and can be detected by ultra-deep sequencing techniques. In this study, we examined the SARS-CoV-2 mutant spectra of amplicons from the spike-coding (S-coding) region of 5 nasopharyngeal isolates derived from patients with vaccine breakthrough. Interestingly, all patients became infected with the Alpha variant, but amino acid substitutions that correspond to the Delta Plus, Iota, and Omicron variants were present in the mutant spectra of the resident virus. Deep sequencing analysis of SARS-CoV-2 from patients with vaccine breakthrough revealed a rich reservoir of mutant types and may also identify tolerated substitutions that can be represented in epidemiologically dominant variants.
Brenda Martínez-González, Lucía Vázquez-Sirvent, María E. Soria, Pablo Mínguez, Llanos Salar-Vidal, Carlos García-Crespo, Isabel Gallego, Ana I. de Ávila, Carlos Llorens, Beatriz Soriano, Ricardo Ramos-Ruiz, Jaime Esteban, Ricardo Fernandez-Roblas, Ignacio Gadea, Carmen Ayuso, Javier Ruíz-Hornillos, Concepción Pérez-Jorge, Esteban Domingo, Celia Perales
BACKGROUND Hyaluronan (HA), an extracellular matrix glycosaminoglycan, has been implicated in the pathophysiology of COVID-19 infection, pulmonary hypertension, pulmonary fibrosis, and other diseases, but is not targeted by any approved drugs. We asked whether hymecromone (4-methylumbelliferone [4-MU]), an oral drug approved in Europe for biliary spasm treatment that also inhibits HA in vitro and in animal models, could be repurposed as an inhibitor of HA synthesis in humans.METHODS We conducted an open-label, single-center, dose-response study of hymecromone in healthy adults. Subjects received hymecromone at 1200 (n = 8), 2400 (n = 9), or 3600 (n = 9) mg/d divided into 3 doses daily, administered orally for 4 days. We assessed safety and tolerability of hymecromone and analyzed HA, 4-MU, and 4-methylumbelliferyl glucuronide (4-MUG; the main metabolite of 4-MU) concentrations in sputum and serum.RESULTS Hymecromone was well tolerated up to doses of 3600 mg/d. Both sputum and serum drug concentrations increased in a dose-dependent manner, indicating that higher doses lead to greater exposures. Across all dose arms combined, we observed a significant decrease in sputum HA from baseline after 4 days of treatment. We also observed a decrease in serum HA. Additionally, higher baseline sputum HA levels were associated with a greater decrease in sputum HA.CONCLUSION After 4 days of exposure to oral hymecromone, healthy human subjects experienced a significant reduction in sputum HA levels, indicating this oral therapy may have potential in pulmonary diseases where HA is implicated in pathogenesis.TRIAL REGISTRATION ClinicalTrials.gov NCT02780752.FUNDING Stanford Medicine Catalyst, Stanford SPARK, Stanford Innovative Medicines Accelerator program, NIH training grants 5T32AI052073-14 and T32HL129970.
Joelle I. Rosser, Nadine Nagy, Riya Goel, Gernot Kaber, Sally Demirdjian, Jamie Saxena, Jennifer B. Bollyky, Adam R. Frymoyer, Ana E. Pacheco-Navarro, Elizabeth B. Burgener, Jayakumar Rajadas, Zhe Wang, Olga Arbach, Colleen E. Dunn, Anissa Kalinowski, Carlos E. Milla, Paul L. Bollyky