Mazloum et al. report that polycystin-1 and the primary cilium govern the composition, mechanics, and shape of the tubular basement membrane, and that remodeling of this matrix initiates tubule dilation in autosomal dominant polycystic kidney disease. The cover image is a false-colored transmission electron micrograph of the thinned tubular basement membrane separating two polycystin-1–deficient tubular cells.
STXBP1 variants are a frequent cause of early-onset developmental and epileptic encephalopathies and related neurodevelopmental disorders, but the clinical interpretation of these variants remains a major challenge. Most reported STXBP1 missense variants are classified as variants of uncertain significance (VUS), complicating diagnosis, counseling, and patient eligibility for precision therapies. Here, we developed EpiPred, a gene-specific machine learning classifier that predicts the pathogenicity of STXBP1 missense variants and tests these predictions using empirical evidence from well-established cellular assays. Trained on a curated set of pathogenic and benign variants, EpiPred outperformed global prediction tools in accuracy, sensitivity, and specificity. We validated the model’s predictions using variant effect assays that measure protein abundance, solubility, stability, and interaction with the SNARE complex partner syntaxin 1. These biochemical readouts aligned closely with model outputs and enabled reclassification of several possibly misdiagnosed variants, which warrant further validation and clinical reevaluation. We deployed EpiPred in an interactive web application that allows clinicians, researchers, and patients to explore predictions for all possible STXBP1 missense variants. By identifying likely pathogenic STXBP1 variants, including those that may respond to emerging therapies such as protein stabilizers. By coupling gene-calibrated machine learning with orthogonal variant-effect assays and public deployment, EpiPred provides a transferable framework for VUS resolution, trial enrichment, and precision diagnosis across clinically actionable Mendelian disease genes.
Jeffrey D. Calhoun, Chengbing Wang, Carina G. Biar, Jonathan R. Gunti, John S. Lee, Aaron M. Geller, Jung H. Hong, Santiago Schnell, Louis T. Dang, Yu Wang, Jack M. Parent, Lori L. Isom, Michael D. Uhler, Heather C. Mefford, M. Elizabeth Ross, Vanessa Aguiar-Pulido, Gemma L. Carvill
Advanced prostate cancer has increasingly developed a lethal neuroendocrine form, small cell/neuroendocrine prostate cancer (NEPC), as a consequence of the widespread use of highly potent androgen receptor signaling inhibitors in castration-resistant disease. The molecular mechanisms remain unclear and no effective therapies currently exist. We report that tryptophan hydroxylase 1 (TPH1), the enzyme responsible for peripheral serotonin biosynthesis — a neurotransmitter enriched in neuroendocrine tumors and a classical neuroendocrine biomarker — was upregulated in both de novo and therapy-induced human NEPC. TPH1 upregulation was necessary and sufficient for neuroendocrine differentiation and the NEPC phenotype through its enzymatic activity. Silencing TPH1 suppressed neuroendocrine plasticity and various aggressive behaviors of NEPC cells, including proliferation, invasion, sphere formation, and NEPC tumor xenograft growth. Mechanistically, TPH1 activated mTOR via intracellular serotonin-dependent serotonylation of mTOR at glutamine 2453, which triggered the induction of FOXM1 and E2F1 to drive NEPC differentiation and growth. Importantly, pharmacological inhibition of TPH1 using the clinically available inhibitor LX1606 effectively restricted growth and neuroendocrine marker expression in multiple NEPC cell lines and patient-derived xenografts. Collectively, these findings characterize TPH1’s contribution to NEPC and suggest TPH1 as a potential therapeutic target.
Jing Wei, Jing Wang, Jingrui Chen, Michelle Zhang, Chia-Hui Chen, Tianjie Pu, Alivia O'Brien, Sephtis Hargrove, Eva Corey, Tzu-Ping Lin, Allen C. Gao, Boyang Jason Wu
Pharmacologic immunosuppression is essential for preventing organ rejection and controlling autoimmunity, but profoundly impairs humoral immunity, increasing the risk of vaccine failure and infection. The mechanisms by which immunosuppressive therapies disrupt human B cell responses remain poorly defined. Here, we identified dysregulated lipid metabolism as a central determinant of impaired vaccine response in solid organ transplant recipients (SOTRs). Using high-dimensional immune profiling, single-cell transcriptomics, and functional metabolic assays, we found that effective B cell responses required a homeostatic balance between lipid synthesis and fatty acid oxidation. The widely used immunosuppressive agent, mycophenolic acid (MPA) was strongly associated with vaccine non-response and induced excessive lipid synthesis, lipid accumulation, and mitochondrial stress in B cells. In contrast, CD11c+ B cells retained the capacity to differentiate into plasmablasts in the presence of MPA through elevated expression of CPT1A, a mitochondrial fatty acid transporter, and enhanced fatty acid oxidation. These cells were found to be a key feature of early effective vaccine responses in healthy individuals and SOTRs. Notably, pharmacologic inhibition of cholesterol synthesis partially restored plasmablast differentiation in the presence of MPA. These findings identify B cell lipid metabolism as a critical and targetable regulator of human humoral immunity during immunosuppression.
Elizabeth A. Thompson, Alexis Figueroa, Katerina Roznik, Nicole E. Skinner, Santosh Dhakal, Shuai Li, Luca Biavati, Laura A. Sena, Laila Stoddart, Karli Redinger, Samuel B. Warner, Sabra L. Klein, Nadine Rouphael, Joel N. Blankson, Yolanda Eby, Robert D. Leone, Peter S. Heeger, Mark A. Robien, Christian P. Larsen, Erika L. Pearce, Edward J. Pearce, Hongkai Ji, Andrew H. Karaba, Dorry L. Segev, Aaron A.R. Tobian, William A. Werbel, Andrea L. Cox, Justin R. Bailey
GLP-1 receptor agonists (GLP1RAs) effectively reduce feeding to treat obesity, although nausea and other aversive side effects of these drugs can limit their use. Brainstem circuits that promote satiation and mediate the physiological control of body weight can be distinguished from those that cause aversion. It remains unclear whether brainstem Glp1r neurons contribute to the normal regulation of energy balance and whether GLP1RAs control appetite via circuits distinct from those that mediate aversive responses, however. Here, we silenced Glp1r neurons in the nucleus of the solitary tract or area postrema (NTSGlp1r or APGlp1r neurons, respectively) or restored their GLP1R signaling on an otherwise GLP1R-deficient background to determine physiological and pharmacological roles for each neuron population. Although NTSGlp1r neurons contributed to the normal restraint of food intake and body weight, they failed to mediate GLP1RA-dependent weight loss. In contrast, while we detected no role for APGlp1r neurons in physiological feeding, they mediated both the weight-lowering and aversive effects of GLP1RAs. Therefore, while non-aversive NTSGlp1r neurons control physiologic satiation they do not contribute to weight loss during GLP1RA treatment. Rather, APGlp1r neurons mediate both the weight-lowering and aversive effects of GLP1RAs, preventing the separation of their nauseating and weight-loss effects at a circuit level.
Warren T. Yacawych, Yi Wang, Guoxiang Zhou, Shad Hassan, Cagri Bodur, Elisabeth Walters, John G. Santinga, Frederike Sass, Martin deVaux, Stace Kernodle, Iris Wu, Jenny M. Brown, Dylan M. Belmont-Rausch, Alan C. Rupp, Abigail J. Tomlinson, Zitian Lin, Emma VanTongeren, Anna Secher, Kirsten Raun, Tune H. Pers, Randy J. Seeley, Martin G. Myers Jr., Weiwei Qiu
Obesity-associated inflammation impairs pancreatic β-cell function, yet the mechanisms by which immune cells acutely regulate insulin secretion remain poorly defined. Here, we identify myeloid Gq signaling as an immunometabolic node linking macrophage lipid sensing to impaired insulin secretion. Using chemogenetic DREADD-mediated activation of myeloid Gq, we show that acute macrophage Gq activation impairs glucose-stimulated insulin secretion (GSIS) in vivo, whereas myeloid Gαq ablation enhances GSIS. Mechanistically, Gq activation rapidly induced AMPK phosphorylation and sphingolipid remodeling independently of canonical inflammatory cytokines. Macrophage-derived sphingolipids impaired β-cell insulin signaling and GSIS through CD36-PKCζ, while inhibition of CD36, AMPK, or sphingolipid metabolism restored β-cell function. We further identified GPR18, a Gq-coupled endocannabinoid-responsive GPCR, as an upstream regulator. GPR18 activation with N-arachidonoyl glycine (NAGly) recapitulated this phenotype, whereas myeloid Gαq deletion or Gpr18/AMPK silencing abolished it. GPR18 signaling predominantly engaged Gq rather than Gi pathways. In human tissues, GPR18 was enriched in islet macrophages, and NAGly suppressed GSIS in primary human islets. Thus, a conserved macrophage GPR18-Gαq-AMPK-sphingolipid axis dynamically regulates β-cell function and represents a potential therapeutic target in obesity and type 2 diabetes.
Simran Singh, Ashish Kumar, Sudipta Paul, Mriganka Sarkar, Santhosh Duraisamy, Ganesh Timalsina, Raashidha Farhath, Harender Yadav, Seema Kuldeep, Soumita Bhaumik, Kunj Kumar Prajapati, Saahiba Thaleshwari, Anuj Gargya, Tamojit Santra, Sonal Amit, Rashmi Parihar, Santosh K. Misra, Hamim Zafar, Luiz F. Barella, Michael A. Kalwat, Dharmaraja Allimuthu, Sai Prasad Pydi
The cyclic GMP-AMP synthase (cGAS)–stimulator of interferon genes (STING) pathway is a key component of innate immunity, linking DNA detection to inflammatory and antiviral responses. Originally identified as a sensor for microbial DNA, cGAS is now understood to also respond to endogenous cytosolic DNA, and the pathway has been implicated in a wide range of physiological and pathological processes, including cancer, autoimmunity, neuroinflammation, and aging. This review series, organized by Dr. Alex Stegh, consolidates current knowledge and highlights emerging developments that may lead to therapeutic targeting of the cGAS-STING pathway across a range of disorders.
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