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.
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
Successful implantation requires precise coordination of uterine epithelial receptivity, stromal decidualization, and immune homeostasis during a narrow peri-implantation window. Although retinoic acid (RA) signaling has been implicated in female reproduction, the endogenous and isoform-specific roles of retinoic acid receptors (RARs) remain poorly defined. Here, we combined isoform-specific genetic mouse models, transcriptomic profiling, and functional studies in mouse and human stromal cells to determine how RAR signaling regulates early pregnancy. We found that RARG is the dominant RAR isoform required for female fertility in mice, as its deletion severely impaired implantation, whereas combined loss of all RAR isoforms caused complete reproductive failure. RAR deficiency disrupted multiple sequential reproductive processes, including sperm transport and fertilization, suppression of uterine estrogen receptor activity, acquisition of stromal decidualization competence, and maintenance of uterine immune homeostasis. Transcriptomic analyses identified conserved epithelial and mesenchymal programs altered across independent RAR-deficient mouse models and revealed significant overlap with endometrial gene signatures from women with recurrent implantation failure. In human endometrial stromal cells, suppression of the RARA isoform consistently disrupted decidualization across three independent primary cell lines and an immortalized cell model. Together, these findings identify RAR signaling as a critical regulator of early pregnancy and reveal conserved, isoform-specific functions required for early pregnancy.
Yan Yin, Emily Y. So, Eliana Wolf, Vivian Robles Pinos, Meade Haller, Renjie Shang, Sylvia C. Hewitt, Alex Tak, Brent M. Bany, David Y. Chen, Mengcheng Shen, Francesco J. DeMayo, Liang Ma
Microglia play essential yet poorly understood roles in brain development, including axon guidance, regulation of neurogenesis, and pruning of neuronal projections. Congenital hydrocephalus (CH), characterized by enlarged cerebrospinal fluid (CSF)-filled ventricles, is a leading cause of pediatric brain surgery, but its molecular mechanisms remain unclear. We have identified what we believe to be novel, recurrent, damaging missense variants in the SH3-binding domain of the adaptor protein Growth Factor Receptor-Bound Protein 2 (GRB2) in unrelated patients with CH. GRB2 is significantly co-expressed with one of its known upstream receptor tyrosine kinase partners, CSF1R, in the developing human brain, particularly in a microglial subtype associated with regulation of neural stem cells. Immunoprecipitation validated GRB2-CSF1R binding in mouse microglial cells and human monocyte cell line. Cx3cr1-Grb2fl/fl mice engineered with conditional deletion of Grb2 in microglia exhibit congenital absence of microglia and early postnatal severe communicating (non-obstructive) hydrocephalus, mimicking GRB2-mutant patients. The severe ventriculomegaly of Cx3cr1-Grb2fl/fl mice is associated with both depletion of cerebral cortical neurons and impairment of glia-lymphatic-mediated CSF flow. Together, these findings implicate a role of GRB2 in microglia that could be essential for brain development and CSF homeostasis.
Phan Q. Duy, Benjamin C. Reeves, Huanxing Sun, Xueyan Peng, Pazhanichamy Kalailingam, Garrett Allington, Evan Dennis, Le Thi Hao, Lei Wang, David Rufino-Ramos, Shujuan Zhao, Qiang Li, Neel H. Mehta, William C. Davalan, Mason Blacker, Anthony J. Piscopo, Shozeb Haider, Baojian Fan, Kedous Y. Mekbib, Shuai Shao, Carol Nelson-Williams, TuKiet T. Lam, Benjamin P. Kleinstiver, Patricia L. Musolino, Seth L. Alper, Sheng Chih Jin, Erica L. Herzog, Kristopher T. Kahle
Membranous nephropathy (MN) is an autoimmune kidney disease and a major cause of nephrotic syndrome in adults. Although autoantibodies against phospholipase A2 receptor 1 (PLA2R) and complement activation are central to disease pathogenesis, the mechanisms by which anti-PLA2R antibodies activate complement at the podocyte surface remain incompletely defined. Here, we cloned 14 patient-derived anti-PLA2R monoclonal antibodies (mAbs) and found that they predominantly recognized the N-terminal cysteine-rich (CysR) and C-type lectin domain 1 (CTLD1) regions of PLA2R. Individual anti-PLA2R mAbs induced little or no complement-dependent cytotoxicity (CDC) of PLA2R-expressing podocytes in vitro. In contrast, paired mAbs targeting distinct epitopes, particularly CysR and CTLD1, markedly enhanced CDC. This effect was strongest for IgG1 and IgG3 antibodies, whereas IgG4 alone did not activate complement but modulated CDC in combination with IgG1. Purified IgG from patients with PLA2R-associated MN similarly induced CDC, which was augmented by addition of anti-PLA2R IgG1 and reduced by anti-PLA2R IgG4 or Fab fragments targeting CysR or CTLD1. In human PLA2R-expressing mice, paired anti-PLA2R antibodies increased glomerular complement deposition and induced albuminuria. These findings identify epitope pairing as a key determinant of complement activation in PLA2R-associated MN and support epitope-specific targeting strategies as a promising avenue for therapeutic intervention.
Tsai-Yi Wu, Kun-Hua Tu, Larissa Seifert, Kung-Wei Lin, Han-Po Shih, Yu-Fang Lo, Jhan-Jie Peng, Gunther Zahner, Oliver Kretz, You-Ning Lin, Chen-Xuan Kang, Jing-Ya Ding, Yi-Ran Tu, Li-Yi Ma, Ya-Ting Chuang, Chia-Chi Lo, Yu-Huan Tsai, Chih-Wei Yang, Nicola M. Tomas, Cheng-Lung Ku
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.
×