Lymphangioleiomyomatosis (LAM) is a progressive cystic lung disease caused by tuberous sclerosis complex 1/2 (TSC1/2) gene mutations in pulmonary mesenchymal cells resulting in activation of the mechanistic target of rapamycin complex 1 (mTORC1). A subset of LAM patients develops pulmonary vascular remodeling and pulmonary hypertension. Little, however, is known regarding how LAM cells communicate with endothelial cells (ECs) to trigger vascular remodeling. In end-stage LAM lung explants, we identified endothelial cell dysfunction characterized by increased proliferation, migration, defective angiogenesis, and dysmorphic endothelial tube network formation. To model LAM disease, we utilized an mTORC1 gain-of-function mouse model with a Tsc2 knock-out (Tsc2KO) specific to lung mesenchyme (Tbx4LME-CreTsc2fl/fl), similar to the mesenchyme specific genetic alterations seen in human disease. As early as 8 weeks of age, ECs from Tbx4LME-CreTsc2fl/fl mice exhibited marked transcriptomic changes despite absence of morphological changes to the distal lung microvasculature. In contrast, 1 year old Tbx4LME-CreTsc2fl/fl mice spontaneously developed pulmonary vascular remodeling with increased medial thickness. Single cell RNA-sequencing of 1 year old mouse lung identified paracrine ligands originating from Tsc2KO mesenchyme which can signal through receptors in arterial ECs. These ECs had transcriptionally altered genes including those in pathways associated with blood vessel remodeling. The proposed pathophysiologic mesenchymal ligand/ EC receptor crosstalk highlights the importance of an altered mesenchymal-EC axis in LAM and other hyperactive mTORC1-driven diseases. Since ECs in LAM patients and in Tbx4LME-CreTsc2fl/fl mice do not harbor TSC2 mutations, our study demonstrates that constitutively active mTORC1 lung mesenchymal cells orchestrate dysfunctional EC responses which contribute to pulmonary vascular remodeling.
Susan M. Lin, Ryan Rue, Alexander R. Mukhitov, Akansha Goel, Maria C. Basil, Kseniya Obraztsova, Apoorva Babu, Slaven Crnkovic, Owen Ledwell, Laura T. Ferguson, Joseph D. Planer, Ana N. Nottingham, Kanth Swaroop Vanka, Carly J. Smith, Edward Cantu III, Grazyna Kwapiszewska, Edward E. Morrisey, Jillian F. Evans, Vera P. Krymskaya
In a structure-function study of sulfatides, that typically stimulate type II NKT cells, we made an unexpected discovery. We compared analogues with sphingosine or phytosphingosine chains and 24-carbon acyl chains with 0-1-2 double bonds (C or pC24:0, 24:1, or 24:2). C24:1 and C24:2 sulfatide presented by CD1d monomer on plastic stimulated type II, not type I, NKT-cell hybridomas as expected. Unexpectedly, when presented by bone-marrow-derived DCs (BMDCs), C24:2 reversed specificity to stimulate type I, not type II, NKT-cell hybridomas, mimicking the corresponding βGalCer without sulfate. It induced IFNγ-dependent immunoprotection against CT26 colon-cancer lung metastases, skewed the cytokine profile, and activated cDC1s. This was abrogated by blocking lysosomal processing with bafilomycin A1, or sulfite-blocking or deletion of arylsulfatase A that cleaves off sulfate. Thus, C24:2 is unexpectedly processed in BMDCs from a type II to a type I NKT cell-stimulating ligand, promoting tumor immunity. We believe this is the first discovery of antigen processing of glycosylceramides altering the specificity for the target cell that reverses its function from stimulating type II to stimulating type I NKT cells, introducing protective functional activity in cancer. It also uncovers a new role for antigen processing, not to allow MHC loading but to alter the cell responding.
Kumiko Nishio, Lise Pasquet, Kaddy Camara, Julia DiSapio, Shingo Kato, Kevin S. Hsu, Anja Bloom, Stewart K. Richardson, Joshua A. Welsh, Tianbo Jiang, Jennifer C. Jones, Susanna Cardell, Hiroshi Watarai, Masaki Terabe, Purevdorj B. Olkhanud, Amy R. Howell, Jay A. Berzofsky
Elevation of reactive oxygen species (ROS) levels is a general consequence of tumor cells’ response to treatment and may cause tumor cell death. Mechanisms by which tumor cells clear fatal ROS, thereby rescuing redox balance and entering a chemoresistant state, remain unclear. Here, we show that cysteine sulfenylation by ROS confers on aryl hydrocarbon receptor (AHR) the ability to dissociate from the heat shock protein 90 complex but to bind to the PPP1R3 family member PPP1R3C of the glycogen complex in drug-treated tumor cells, thus activating glycogen phosphorylase to initiate glycogenolysis and the subsequent pentose phosphate pathway, leading to NADPH production for ROS clearance and chemoresistance formation. We found that basic ROS levels were higher in chemoresistant cells than in chemosensitive cells, guaranteeing the rapid induction of AHR sulfenylation for the clearance of excess ROS. These findings reveal that AHR can act as an ROS sensor to mediate chemoresistance, thus providing a potential strategy to reverse chemoresistance in patients with cancer.
Nannan Zhou, Jie Chen, Zheng Ling, Chaoqi Zhang, Yabo Zhou, Dianheng Wang, Li Zhou, Zhenfeng Wang, Nan Sun, Xin Wang, Huafeng Zhang, Ke Tang, Jingwei Ma, Jiadi Lv, Bo Huang
About 25% of people within the general population are insulin resistant, increasing the risk for type 2 diabetes (T2D) and metabolic disease. Transcriptomic analysis of iPS cells differentiated into myoblasts (iMyos) from insulin resistant (I-Res) versus insulin sensitive (I-Sen) non-diabetic individuals reveals 306 genes increased and 271 genes decreased in expression in iMyos from insulin resistant donors with differences of 2-folds or more. Over 30 of the genes changed in I-Res iMyos are associated with T2D by SNP polymorphisms and functionally linked to insulin action and control of metabolism. Interestingly, we also identified >1500 differences in gene expression that were dependent on sex of the cell donor, some of which modified the insulin resistance effects. Many of these sex-differences were associated with increased DNA methylation in cells from females and reversed by 5-azacytidine. By contrast, the insulin sensitivity differences were not reversed and thus appear to reflect genetic or methylation-independent epigenetic effects.
Nida Haider, C. Ronald Kahn
Cholera is a global health problem with no targeted therapies. Ca2+-sensing receptor (CaSR) is regulator of intestinal ion transport and therapeutic target for diarrhea, and Ca2+ is considered its main agonist. We found that increasing extracellular Ca2+ had minimal effect on forskolin-induced Cl- secretion in human intestinal epithelial T84 cells. However, extracellular Mg2+, an often-neglected CaSR agonist, suppressed forskolin-induced Cl- secretion in T84 cells by 65% at physiological levels seen in stool (10 mM). Mg2+ effect was via CaSR-Gq signaling that leads to cAMP hydrolysis. Mg2+ (10 mM) also suppressed Cl- secretion induced by cholera toxin, heat-stable E. coli enterotoxin and vasoactive intestinal peptide by 50%. In mouse intestinal closed-loops, luminal Mg2+ treatment (20 mM) inhibited cholera toxin-induced fluid accumulation by 40%. In mouse intestinal perfusion model of cholera, adding 10 mM Mg2+ to the perfusate reversed the net fluid transport from secretion to absorption. These results suggest that Mg2+ is the key CaSR activator in mouse and human intestinal epithelia at physiological levels seen in stool. Since stool Mg2+ concentrations in cholera patients are essentially zero, oral Mg2+ supplementation, alone or in oral rehydration solution (ORS), can be a potential therapy for cholera and other cyclic nucleotide-mediated secretory diarrheas.
Livia de Souza Goncalves, Qi Tifany Chu, Riya Master, Parth D. Chhetri, Qi Gao, Onur Cil
Recent studies using cell type-specific knockout mouse models have improved our understanding of the pathophysiological relevance of SEL1L-HRD1 endoplasmic reticulum (ER)-associated degradation (ERAD); however, its importance in humans remains unclear as no disease variant has been identified. Here we report the identification of three bi-allelic missense variants of SEL1L and HRD1 (or SYVN1) in six children from three independent families presenting with developmental delay, intellectual disability, microcephaly, facial dysmorphisms, hypotonia and/or ataxia. These SEL1L (p.Gly585Asp, p.Met528Arg) and HRD1 (p.Pro398Leu) variants were hypomorphic and impaired ERAD function at distinct steps of ERAD including substrate recruitment (SEL1L p.Gly585Asp), SEL1L-HRD1 complex formation (SEL1L p.Met528Arg), and HRD1 activity (HRD1 p.Pro398Leu). Our study not only provide new insights into the structure-function relationship of SEL1L-HRD1 ERAD, but also establish the importance of SEL1L-HRD1 ERAD in humans.
Huilun Helen Wang, Liangguang Leo Lin, Zexin Jason Li, Xiaoqiong Wei, Omar Askander, Gerarda Cappuccio, Mais O. Hashem, Laurence Hubert, Arnold Munnich, Mashael Alqahtani, Qi Pang, Margit Burmeister, You Lu, Karine Poirier, Claude Besmond, Shengyi Sun, Nicola Brunetti-Pierri, Fowzan S. Alkuraya, Ling Qi
SEL1L-HRD1 ERAD plays a critical role in many physiological processes in mice, including immunity, water homeostasis and energy metabolism; however, its relevance and importance in humans remain unclear as no disease variant has been identified. Here we report a bi-allelic SEL1L variant (p. Cys141Tyr) in five patients from a consanguineous Slovakian family. These patients presented with not only ERAD-associated neurodevelopmental disorders with onset infancy (ENDI) syndromes, but infantile-onset agammaglobulinemia with no mature B cells, resulting in frequent infections and early death. This variant disrupted the formation of a disulfide bond in the luminal fibronectin II domain of SEL1L, largely abolishing the function of SEL1L-HRD1 ERAD complex in part via proteasomal-mediated self-destruction by HRD1. This study reports a new disease entity termed the “ENDI-agammaglobulinemia” (ENDI-A) syndrome and establishes an inverse correlation between SEL1L-HRD1 ERAD functionality and disease severity in humans.
Denisa Weis, Liangguang Leo Lin, Huilun Helen Wang, Zexin Jason Li, Katarína Kušíková, Peter Ciznar, Hermann Maximillian Wolf, Alexander Leiss-Piller, Zhihong Wang, Xiaoqiong Wei, Serge Weis, Katarina Skalicka, Gabriela Hrckova, Lubos Danisovic, Andrea Soltysova, Tingxuan Tina Yang, René Günther Feichtinger, Johannes Adalbert Mayr, Ling Qi
Mutations in the BRCA2 tumor suppressor gene have been associated with an increased risk of developing prostate cancer. One of the paradoxes concerning BRCA2 is the fact that its inactivation affects genetic stability and is deleterious for cellular and organismal survival, while BRCA2-mutated cancer cells adapt to this detriment and malignantly proliferate. Therapeutic strategies for tumors arising from BRCA2 mutations may be discovered by understanding these adaptive mechanisms. In this study, we conducted forward genetic synthetic viability screenings in C. elegans brc-2 (Cebrc-2) mutants and found that Ceubxn-2 inactivation rescued the viability of Cebrc-2 mutants. Moreover, loss of NSFL1C, the mammalian ortholog of CeUBXN-2, suppressed the spindle assembly checkpoint (SAC) activation and promoted the survival of BRCA2-deficient cells. Mechanistically, NSFL1C recruited USP9X to inhibit the polyubiquitination of AURKB and reduce the removal of AURKB from the centromeres by VCP, which is essential for SAC activation. SAC inactivation is common in BRCA2-deficient prostate cancer patients, but PP2A inhibitors could reactivate the SAC and achieve BRCA2-deficient prostate tumor synthetic lethality. Our research reveals the survival adaptation mechanism of BRCA2-deficient prostate tumor cells and provides different angles for exploring synthetic lethal inhibitors in addition to targeting DNA damage repair pathways.
Jian Wang, Yuke Chen, Shiwei Li, Wanchang Liu, Xiao Albert Zhou, Yefei Luo, Zhanzhan Xu, Yundong Xiong, Kaiqi Cheng, Mingjian Ruan, Wei Yu, Xiaoman Li, Weibin Wang, Jiadong Wang
The G protein-coupled receptor 84 (GPR84), a medium-chain fatty acid receptor, has garnered attention because of its potential involvement in a range of metabolic conditions. However, the precise mechanisms underlying this effect remain elusive. Our study has shed light on the pivotal role of GPR84, revealing its robust expression and functional significance within the brown adipose tissue (BAT). Mice lacking GPR84 exhibited increased lipid accumulation in BAT, rendering them more susceptible to cold exposure, and displaying reduced BAT activity compared to their wild-type counterparts. Our in vitro experiments with primary brown adipocytes from GPR84 knockout mice revealed diminished expression of thermogenic genes and reduced O2 consumption. Furthermore, the application of the GPR84 agonist 6-OAU counteracted these effects, effectively reinstating the brown adipocyte activity. These compelling in vivo and in vitro findings converge to highlight mitochondrial dysfunction as the primary cause of BAT anomalies in GPR84 knockout mice. The activation of GPR84 induced an increase in intracellular Ca2+ levels, which intricately influences mitochondrial respiration. By modulating mitochondrial Ca2+ levels and respiration, GPR84 has emerged as a potent molecule involved in BAT activity. These findings suggested that GPR84 is a potential therapeutic target for invigorating BAT and ameliorating metabolic disorders.
Xuenan Sun, Yu A. An, Vivian A. Paschoal, Camila O. De Souza, May-yun Wang, Lavanya Vishvanath, Lorena M.A. Bueno, Ayanna S. Cobb, Joseph A. Nieto Carrion, Madison E. Ibe, Chao Li, Harrison A. Kidd, Shiuhwei Chen, Wenhong Li, Rana K. Gupta, Da Young Oh
The progression of proteinuric kidney diseases is associated with podocyte loss but the mechanisms underlying this process remain unclear. Podocytes re-enter the cell cycle to repair double-stranded DNA (dsDNA) breaks. However, the unsuccessful repair can result in podocytes crossing the G1/S checkpoint and undergoing abortive cytokinesis. In this study, we identified Pfn1 as indispensable in maintaining glomerular integrity - its tissue-specific loss in mouse podocytes results in severe proteinuria and kidney failure. Our results suggest that this phenotype is due to podocyte mitotic catastrophe (MC), characterized histologically and ultrastructurally by abundant multinucleated cells, irregular nuclei, and mitotic spindles. Podocyte cell cycle re-entry was identified using FUCCI2aR mice and observed altered expression of cell-cycle associated proteins such as p21, p53, Cyclin B1, and Cyclin D1. Podocyte-specific translating ribosome affinity purification (TRAP) and RNAseq revealed the downregulation of Ribosomal RNA-processing protein 8 (Rrp8). Over-expression of Rrp8 in Pfn1 KO podocytes partially rescued the phenotype in vitro. Clinical and ultrastructural tomographic analysis of patients with diverse proteinuric kidney diseases further validated the presence of MC podocytes and reduction in podocyte PFN1 expression within kidney tissues. These results suggest that profilin1 is essential in regulating the podocyte cell cycle and its disruption leads to MC and subsequent podocyte loss.
Xuefei Tian, Christopher E. Pedigo, Ke Li, Xiaotao Ma, Patricia Bunda, John Pell, Angela Lek, Jianlei Gu, Yan Zhang, Paulina X. Medina Rangel, Wei Li, Eike Schwartze, Soichiro Nagata, Gabriel Lerner, Sudhir Perincheri, Anupama Priyadarshini, Hongyu Zhao, Monkol Lek, Madhav C. Menon, Rongguo Fu, Shuta Ishibe
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