COVID-19 infection causes collapse of glomerular capillaries and loss of podocytes, terminating in a severe kidney disease called COVID-19 associated nephropathy (COVAN). The underlying mechanism of COVAN is unknown. We hypothesized that cytokines induced by COVID-19 trigger expression of pathogenic APOL1 via JAK-STAT signaling, resulting in podocyte loss and COVAN phenotype. Here, based on nine biopsy-proven COVAN cases, we demonstrated for the first time that APOL1 protein is abundantly expressed in podocytes and glomerular endothelial cells (GECs) of COVAN kidneys but not in controls. Moreover, a majority (77.8%) of COVAN patients carried two APOL1 risk alleles. We showed that recombinant cytokines induced by SARS-CoV-2 act synergistically to drive APOL1 expression through the JAK-STAT pathway in primary human podocytes, GECs, and kidney micro-organoids derived from a carrier of two APOL1 risk alleles but was blocked by JAK1/2-inhibitor, baricitinib. We demonstrated for the first time that cytokine-induced JAK-STAT-APOL1 signaling reduced the viability of kidney organoid podocytes but was rescued by baricitinib. Together, our results support the conclusion that COVID-19-induced cytokines are sufficient to drive COVAN-associated podocytopathy via JAK-STAT-APOL1 signaling and that JAK-inhibitor could block this pathogenic process. These findings suggest that JAK-inhibitors may have therapeutic benefits for managing cytokine-induced APOL1-mediated podocytopathy.
Sarah E. Nystrom, Guojie Li, Somenath Datta, Karen Soldano, Daniel Silas, Astrid Weins, Gentzon Hall, David B. Thomas, Opeyemi A. Olabisi
Systemic therapies for pancreatic ductal adenocarcinoma (PDAC) remain unsatisfactory. Clinical prognosis is particularly poor for tumor subtypes with activating aberrations in the MYC pathway creating an urgent need for novel therapeutic targets. To unbiasedly find novel MYC-associated epigenetic dependencies, we conducted a drug screen in pancreatic cancer cell lines. Here, we found protein arginine N-methyltransferase 5 (PRMT5) inhibitors to trigger a MYC-associated dependency. In human and murine PDACs, a robust connection of MYC and PRMT5 was detected. By the use of gain- and loss-of-function models, we confirm the increased efficacy of PRMT5 inhibitors in MYC deregulated PDACs. Although inhibition of PRMT5 is inducing DNA-damage and arresting PDAC cells in the G2/M-phase of the cell cycle, apoptotic cell death was executed predominantly in cells with high MYC expression. Experiments in primary patient-derived PDAC models demonstrated the existence of a highly PRMT5 inhibitor sensitive subtype. Our work suggests developing PRMT5 inhibitor-based therapies for PDAC.
Felix Orben, Katharina Lankes, Christian Schneeweis, Zonera Hassan, Hannah Jakubowsky, Lukas Krauß, Fabio Boniolo, Carolin Schneider, Arlett P.G. Schäfer, Janine Murr, Christoph Schlag, Bo Kong, Rupert Öllinger, Chengdong Wang, Georg Beyer, Ujjwal Mukund Mahajan, Yonggan Xue, Julia Mayerle, Roland M. Schmid, Bernhard Kuster, Roland Rad, Christian J. Braun, Matthias Wirth, Maximilian Reichert, Dieter Saur, Günter Schneider
HDL cholesterol (HDL-C) predicts risk of cardiovascular disease (CVD), but the factors regulating HDL are incompletely understood. Emerging data link CVD risk to decreased HDL-C in 8% of the world population and 40% of East Asians who carry an SNP of aldehyde dehydrogenase 2 (ALDH2) rs671, responsible for alcohol flushing syndrome; however, the underlying mechanisms remain unknown. We found significantly decreased HDL-C with increased hepatosteatosis in ALDH2-KO (AKO), ALDH2/LDLR–double KO (ALKO), and ALDH2 rs671–knock-in (KI) mice after consumption of a Western diet. Metabolomics identified ADP-ribose as the most significantly increased metabolites in the ALKO mouse liver. Moreover, ALDH2 interacted with poly(ADP-ribose) polymerase 1 (PARP1) and attenuated PARP1 nuclear translocation to downregulate poly(ADP-ribosyl)ation of liver X receptor α (LXRα), leading to an upregulation of ATP-binding cassette transporter A1 (ABCA1) and HDL biogenesis. Conversely, AKO or ALKO mice exhibited lower HDL-C with ABCA1 downregulation due to increased nuclear PARP1 and upregulation of LXRα poly(ADP-ribosyl)ation. Consistently, PARP1 inhibition rescued ALDH2 deficiency–induced fatty liver and elevated HDL-C in AKO mice. Interestingly, KI mouse or human liver tissues showed ABCA1 downregulation with increased nuclear PARP1 and LXRα poly(ADP-ribosyl)ation. Our study uncovered a key role of ALDH2 in HDL biogenesis through the LXRα/PARP1/ABCA1 axis, highlighting a potential therapeutic strategy in CVD.
Luxiao Li, Shanshan Zhong, Rui Li, Ningning Liang, Lili Zhang, Shen Xia, Xiaodong Xu, Xin Chen, Shiting Chen, Yongzhen Tao, Huiyong Yin
Platelet homeostasis is dependent on a tight regulation of both platelet production and clearance. The small GTPase Rap1 mediates platelet adhesion and hemostatic plug formation. However, Rap1 signaling is also critical for platelet homeostasis as both Rap1 deficiency and uninhibited Rap1 signaling lead to marked thrombocytopenia in mice. Here we investigated the mechanism by which deficiency in Rasa3, a critical negative regulator of Rap1, causes macrothrombocytopenia in mice. Despite marked morphological and ultrastructural abnormalities, megakaryocytes in hypomorphic Rasa3hlb/hlb or Rasa3-/- mice demonstrated robust proplatelet formation in vivo, suggesting that defective thrombopoiesis is not the main cause of thrombocytopenia. Rather, we observed that Rasa3hlb/hlb platelets become trapped in the spleen marginal zone/red pulp interface, with evidence of platelet phagocytosis by macrophages. Clearance of mutant platelets was also observed in the liver, especially in splenectomized mice. Platelet count and platelet lifespan in Rasa3 mutant mice were restored by genetic or pharmacological approaches to inhibit the Rap1/Talin1/αIIbβ3 integrin axis. A similar pattern of splenic clearance was observed in mice injected with anti-αIIbβ3 but not anti-GPIbα platelet-depleting antibodies. In summary, we describe a novel, integrin-based mechanism of platelet clearance that could be critical for our understanding of select inherited and acquired thrombocytopenias.
Robert H Lee, Dorsaf Ghalloussi, Gabriel L. Harousseau, Joseph P. Kenny, Patrick A. Kramer, Fabienne Proamer, Bernhard Nieswandt, Matthew J. Flick, Christian Gachet, Caterina Casari, Anita Eckly, Wolfgang Bergmeier
Parturition is a well-orchestrated process characterized by increased uterine contractility, cervical ripening, and activation of the chorioamniotic membranes; yet, the transition from a quiescent to a contractile myometrium heralds the onset of labor. However, the cellular underpinnings of human parturition in the uterine tissues are still poorly understood. Herein, we performed a comprehensive study of the human myometrium during spontaneous term labor using single-cell RNA sequencing (scRNA-Seq). First, we established a single-cell atlas of the human myometrium and unraveled the cell type–specific transcriptomic activity modulated during labor. Major cell types included distinct subsets of smooth muscle cells, monocytes/macrophages, stromal cells, and endothelial cells, all of which communicated and participated in immune (e.g., inflammation) and nonimmune (e.g., contraction) processes associated with labor. Furthermore, integrating scRNA-Seq and microarray data with deconvolution of bulk gene expression highlighted the contribution of smooth muscle cells to labor-associated contractility and inflammatory processes. Last, myometrium-derived single-cell signatures can be quantified in the maternal whole-blood transcriptome throughout pregnancy and are enriched in women in labor, providing a potential means of noninvasively monitoring pregnancy and its complications. Together, our findings provide insights into the contributions of specific myometrial cell types to the biological processes that take place during term parturition.
Roger Pique-Regi, Roberto Romero, Valeria Garcia-Flores, Azam Peyvandipour, Adi L. Tarca, Errile Pusod, Jose Galaz, Derek Miller, Gaurav Bhatti, Robert Para, Tomi Kanninen, Ola Hadaya, Carmen Paredes, Kenichiro Motomura, Jeffrey R. Johnson, Eunjung Jung, Chaur-Dong Hsu, Stanley M. Berry, Nardhy Gomez-Lopez
Studying temporal gene expression shifts during disease progression provides important insights into the biological mechanisms that distinguish adaptive and maladaptive responses. Existing tools for the analysis of time course transcriptomic data are not designed to optimally identify distinct temporal patterns when analyzing dynamic differentially expressed genes (DDEGs). Moreover, there is a lack of methods to assess and visualize the temporal progression of biological pathways mapped from time course transcriptomic datasets. In this study, we developed an open-source R package TrendCatcher (https://github.com/jaleesr/TrendCatcher), which applies the smoothing spline ANOVA model and break point searching strategy to identify and visualize distinct dynamic transcriptional gene signatures and biological processes from longitudinal datasets. We used TrendCatcher to perform a systematic temporal analysis of COVID-19 peripheral blood transcriptomes, including bulk and single-cell RNA sequencing time course data. TrendCatcher uncovered the early and persistent activation of neutrophils and coagulation pathways as well as impaired type I interferon (IFN-I) signaling in circulating cells as a hallmark of patients who progressed to severe COVID-19, whereas no such patterns were identified in individuals receiving SARS-CoV-2 vaccinations or patients with mild COVID-19. These results underscore the importance of systematic temporal analysis to identify early biomarkers and possible pathogenic therapeutic targets.
Xinge Wang, Mark A. Sanborn, Yang Dai, Jalees Rehman
Cells recognize both foreign and host-derived double-stranded RNA (dsRNA) via a signaling pathway that is usually studied in the context of viral infection. It has become increasingly clear that the sensing and handling of endogenous dsRNA is also critical for cellular differentiation and development. The adenosine RNA deaminase, ADAR1, has been implicated as a central regulator of the dsRNA response, but how regulation of the dsRNA response might mediate cell fate during injury and whether such signaling is cell intrinsic remain unclear. Here, we show that the ADAR1-mediated response to dsRNA was dramatically induced in 2 distinct injury models of gastric metaplasia. Mouse organoid and in vivo genetic models showed that ADAR1 coordinated a cell-intrinsic, epithelium-autonomous, and interferon signaling–independent dsRNA response. In addition, dsRNA accumulated within a differentiated epithelial population (chief cells) in mouse and human stomachs as these cells reprogrammed to a proliferative, reparative (metaplastic) state. Finally, chief cells required ADAR1 to reenter the cell cycle during metaplasia. Thus, cell-intrinsic ADAR1 signaling is critical for the induction of metaplasia. Because metaplasia increases cancer risk, these findings support roles for ADAR1 and the response to dsRNA in oncogenesis.
José B. Sáenz, Nancy Vargas, Charles J. Cho, Jason C. Mills
Cancer inflicts damage to surrounding normal tissues, which can culminate in fatal organ failure. Here, we demonstrate that cell death in organs affected by cancer can be detected by tissue-specific methylation patterns of circulating cell-free DNA (cfDNA). We detected elevated levels of hepatocyte-derived cfDNA in the plasma of patients with liver metastases originating from different primary tumors, compared with cancer patients without liver metastases. In addition, patients with localized pancreatic or colon cancer showed elevated hepatocyte cfDNA, suggesting liver damage inflicted by micrometastatic disease, by primary pancreatic tumor pressing the bile duct, or by a systemic response to the primary tumor. We also identified elevated neuron-, oligodendrocyte-, and astrocyte-derived cfDNA in a subpopulation of patients with brain metastases compared with cancer patients without brain metastasis. Cell type–specific cfDNA methylation markers enabled the identification of collateral tissue damage in cancer, revealing the presence of metastases in specific locations and potentially assisting in early cancer detection.
Asael Lubotzky, Hai Zemmour, Daniel Neiman, Marc Gotkine, Netanel Loyfer, Sheina Piyanzin, Bracha-Lea Ochana, Roni Lehmann-Werman, Daniel Cohen, Joshua Moss, Judith Magenheim, Maureen F. Loftus, Lauren Brais, Kimmie Ng, Raul Mostoslavsky, Brian M. Wolpin, Aviad Zick, Myriam Maoz, Albert Grinshpun, Anatoli Kustanovich, Chen Makranz, Jonathan E. Cohen, Tamar Peretz, Ayala Hubert, Mark Temper, Azzam Salah, Shani Avniel-Polak, Simona Grozinsky-Glasberg, Kirsty L. Spalding, Ariel Rokach, Tommy Kaplan, Benjamin Glaser, Ruth Shemer, Yuval Dor
Lung alveolar type 2 (AT2) cells are progenitors for alveolar type 1 (AT1) cells. Although many factors regulate AT2 cell plasticity, the role of mitochondrial calcium (mCa2+) uptake in controlling AT2 cells remains unclear. We previously identified that the microRNA family, miR-302, supports lung epithelial progenitor cell proliferation and less differentiated phenotypes during development. Here we report that a sustained elevation of miR-302 in adult AT2 cells decreases AT2-to-AT1 cell differentiation during the Streptococcus pneumoniae induced lung injury repair. We identified that miR-302 targets and represses the expression of mitochondrial Ca2+ uptake 1 (MICU1), which regulates mCa2+ uptake through the mCa2+ uniporter channel by acting as a gatekeeper at low cytosolic Ca2+ levels. Our results reveal a marked increase in MICU1 protein expression and decreased mCa2+ uptake during AT2-to-AT1 cell differentiation in the adult lung. Deletion of Micu1 in AT2 cells reduces AT2-to-AT1 cell differentiation during steady-state tissue maintenance and alveolar epithelial regeneration following bacterial pneumonia. These studies indicate that mCa2+ uptake is extensively modulated during AT2-to-AT1 cell differentiation and that MICU1-dependent mCa2+ uniporter channel gating is a prominent mechanism modulating AT2-to-AT1 cell differentiation.
Mir Ali, Xiaoying Zhang, Ryan LaCanna, Dhanendra Tomar, John W. Elrod, Ying Tian
Short stature is a major skeletal phenotype in osteogenesis imperfecta (OI), a genetic disorder mainly caused by mutations in genes encoding type I collagen. However, the underlying mechanism is poorly understood and no effective treatment is available. In OI mice that carry a G610C mutation in COL1A2, we previously found that mature hypertrophic chondrocytes (HCs) are exposed to cell stress due to accumulation of misfolded mutant type I procollagen in the endoplasmic reticulum (ER). By fate mapping analysis of HCs in G610C OI mice, we found that HCs stagnate in the growth plate, inhibiting translocation of HC descendants to the trabecular area and their differentiation to osteoblasts. Treatment with 4-phenylbutyric acid (4PBA), a chemical chaperone, restored HC ER structure and rescued this inhibition, resulting in enhanced longitudinal bone growth in G610C OI mice. Interestingly, the effects of 4PBA on ER dilation were limited in osteoblasts and the bone fragility was not ameliorated. These results highlight the importance of targeting HCs to treat growth deficiency in OI. Our findings demonstrate that HC dysfunction induced by ER disruption plays a critical role in the pathogenesis of OI growth deficiency, which lays the foundation for developing new therapies for OI.
Amanda L. Scheiber, Kevin J. Wilkinson, Akiko Suzuki, Motomi Enomoto-Iwamoto, Takashi Kaito, Kathryn S.E. Cheah, Masahiro Iwamoto, Sergey Leikin, Satoru Otsuru
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