Research Article
Abstract
Renal water reabsorption is classically regulated by vasopressin V2 receptor (V2R) signaling through cyclic AMP and protein kinase A, driving apical accumulation of aquaporin-2 (AQP2). However, collecting duct water handling is also modulated by vasopressin-independent mechanisms. Here, we examined intracellular soluble urate as a vasopressin-independent regulator of AQP2 trafficking. Intracellular urate accumulation in collecting duct cells was mediated by enhanced apical urate uptake via GLUT9b and reduced apical urate efflux through ABCG2, triggering phosphodiesterase-4 activation, reduced cAMP, and downstream AMP-activated protein kinase (AMPK) activation. The resulting AQP2 accumulation at the apical membrane was independent of V2R signaling, required ongoing endocytosis, and was associated with features of postendocytic apical trafficking of internalized AQP2. In vivo ABCG2 inhibition with probenecid increased apical AQP2 abundance and markedly attenuated tolvaptan-induced polyuria in both wild-type and Pkd1RC/RC autosomal dominant polycystic kidney disease (ADPKD) mice in a uricase-independent manner while preserving tolvaptan’s ADPKD-modifying efficacy. In a phase II trial with tolvaptan-treated patients with ADPKD, probenecid reduced urine volume and nocturia frequency. Together, these findings support a vasopressin-independent urate/AMPK/AQP2 pathway that regulates renal water handling and, in a preclinical ADPKD model, can uncouple cyst growth attenuation from the dose-limiting aquaretic effects of V2R antagonism.
Authors
Mohamad Hadla, Jean Marc Mardirossian, Daniel G. Bichet, Abdul Hamid Borghol, Georges Abboud, Ahmad Ghanem, Eduardo Chini, Peter Harris, Vicente E. Torres, Seth L. Alper, Volker Vallon, Fouad T. Chebib
Abstract
CIC::DUX4 sarcoma (CDS) is a lethal cancer driven by a fusion between the tumor suppressor capicua (CIC) and the pioneer transcription factor double homeobox 4 (DUX4). We previously generated 3 genetically engineered mouse models (GEMMs) of CDS with CIC::DUX4 regulated by loxP-STOP-loxP cassettes, however, mice from all 3 models developed spontaneous tumors without Cre recombinase. Here, we established a next-generation GEMM of CDS (dual-flex [dFLEx] CDS) that used a dual recombinase (Cre plus the thermostable mutant of FLP recombinase FLPE) FLEx-switch design to activate CIC::DUX4 expression and initiate sarcomagenesis in a spatially and temporally controlled manner. Because CIC::DUX4 drives sarcoma development by activating an oncogenic transcriptional program, we performed a drug screen on human-derived CDS cell lines using a library of compounds that modulate transcription. This screen identified Minnelide, an inhibitor of RNA polymerase II–mediated transcription, as a selective inhibitor of CDS. Mechanistically, Minnelide acted through xeroderma pigmentosum type B to alter phosphorylation of RPB1, the largest subunit of RNA polymerase II. Subsequently, RPB1 underwent degradation leading to apoptosis of CDS cells. Minnelide demonstrated in vivo efficacy in dFLEx CDS GEMMs and in human CDS xenografts. As Minnelide has already been demonstrated to be safe in clinical trials, these findings identify Minnelide as a potential therapeutic option to test in patients with CDS.
Authors
MaKenna R. Browne, Axel V. Silver, Risha Banerjee, Brendan C. Dickson, Benigno Aquino, Kristianne M. Oristian, Jonathon Himes, Peter G. Hendrickson, David G. Kirsch
Abstract
Based on the observation that loss-of-function mutations of KMT2C and KMT2D (KMT2C/D) are enriched and co-occur in gastric adenocarcinoma, we developed genetically engineered mouse models (GEMMs) to conditionally knock out Kmt2c and Kmt2d in gastric epithelial cells. We observed that Kmt2c/d loss led to nuclear dysplasia, cellular crowding, and expansion of cells with mixed gastric lineage markers. When combined with Pten deletion, Kmt2c/d loss drove rapid development of muscle-invasive gastric adenocarcinoma as early as 3 weeks after Cre-mediated gene deletion. The adenocarcinoma exhibited decreased expression of gastric lineage markers and increased expression of intestinal differentiation markers, phenocopying human intestinal-type gastric adenocarcinoma. Bioinformatic integration of single-cell RNA-seq of our GEMMs and human gastric cancer datasets showed coclustering of normal and of cancerous gastric epithelial cells. Kmt2c/d knockout in gastric epithelium reduced protein synthesis but upregulated transcription of ribosomal proteins, rendering the cells hypersensitive to mTOR complex 1 (mTORC1) inhibitors. Additionally, Kmt2c/d knockout increased MHC class I molecule expression and enhanced antigen presentation. Combination of mTORC1 inhibition and anti–programmed cell death 1 immunotherapy markedly suppressed tumor growth in immune-competent mice. Together, these findings reveal the role of Kmt2c/d loss in gastric cancer initiation and suggest potential therapeutic strategies for KMT2C/D-deficient gastric cancer.
Authors
Naitao Wang, Dan Li, Tao Zhang, Mohini R. Pachai, Dana M. Schoeps, Yudi Bao, Woo Hyun Cho, Makhzuna N. Khudoynazarova, Kae Kristoff, Marion Liu, Laura Tang, Yelena Y. Janjigian, Ping Chi, Yu Chen
Abstract
Studies with a candidate vaccine deleted in glycoprotein D (ΔgD-2) for herpes simplex virus (HSV) prevention uncovered a role for herpes virus entry mediator (HVEM) in mediating antibody-dependent cell-mediated killing (ADCK) of virally infected cells. Antibodies elicited by ΔgD-2 passively protect WT but not Fc γ receptor (FcγR) or HVEM knockout (KO) mice. The goals of this study were to identify which cells mediate ADCK and the role of HVEM signaling. Using HVEM ligand and conditional cell-type–specific HVEM-KO mice combined with in vitro mouse and human cytolytic assays, we demonstrate that ADCK of HSV-infected cells is mediated primarily by neutrophils and requires their expression of HVEM and its ligand, LIGHT. Cytolysis is not associated with granzyme and perforin production but occurs by a trogocytosis-like pathway. Pharmacological inhibition of myosin light-chain kinase (MLCK), which mediates trogocytosis, inhibits cytolysis. Similar results were obtained when human neutrophils were cocultured with HSV-infected cells opsonized with ADCK-containing human immune serum or with breast cancer cells treated with an anti-HER2 trogocytosis mediating antibody. Killing was significantly reduced when an MLCK inhibitor or blocking antibodies to CD16a, HVEM, or LIGHT were added. Together, these results define a mechanism of HVEM-enhanced FcγR-mediated neutrophil-dependent ADCK of targets cells.
Authors
Matthew S. Gromisch, Masayuki Kuraoka, Carl F. Ware, Steven C. Almo, Betsy C. Herold
Abstract
Imaging-based, single-cell, spatial transcriptomics (iSCST) of FFPE tissue enables comprehensive analysis of archived specimens while preserving spatial context, critical to an understanding of ulcerative colitis (UC) pathology. Here, we deployed a robust framework for applying iSCST to clinical FFPE mucosal biopsies from patients with UC or immune checkpoint inhibitor–induced colitis, as well as patients serving as healthy controls. iSCST using custom Xenium gene panels enabled precise detection of diverse cell subsets and disease-specific genes. We mapped transcriptionally distinct fibroblast subsets within mucosal niches, including inflammation-associated fibroblasts (IAFs), and identified colitis-specific neighborhoods formed by IAFs, monocytes, and neutrophils. Transcriptional signatures and spatial neighborhoods uncovered through iSCST were associated with vedolizumab (VDZ) response, with nonresponders exhibiting either an innate IAF-monocyte-neutrophil signature or adaptive gut-associated lymphoid tissue signature, while responders showed enrichment of an epithelial cellular neighborhood. These signatures were validated in an internal and an external dataset, supporting the existence of 2 distinct archetypes of treatment resistance to VDZ in UC. This iSCST framework provides a powerful approach for analyzing FFPE tissues, offering insights into colitis-associated cellular networks and identifying biomarkers to enhance patient risk stratification in routine clinical workflows.
Authors
Elvira Mennillo, Madison L. Lotstein, Gyehyun Lee, Julian H. Hou, Vrinda Johri, Donna E. Leet, Christina A. Ekstrand, Jessica Tsui, Jun Yan He, Uma Mahadevan, Walter Eckalbar, Ryan M. Gill, Christopher J. Bowman, David Y. Oh, Gabriela K. Fragiadakis, Michael G. Kattah, Alexis J. Combes
Abstract
Antimetabolites, chemotherapy targeting nucleotide biosynthesis, are among the oldest and most widely used cancer treatments, yet resistance remains a daunting barrier, especially in the fight against B cell lymphomas. However, the underlying mechanisms of this resistance have long remained elusive. Using an innovative, integrated omics approach, we unexpectedly identified that the accumulation of dipeptides and upregulation of the dipeptide transporter SLC15A3 underlie resistance to nucleotide deficiency in a Myc-driven large B cell lymphoma mouse model. A similar mechanism occurred after long treatment of human B cell lymphoma cells with the chemotherapeutic purine synthesis inhibitor 6-mercaptopurine (6MP). Mechanistically, we demonstrated that dipeptides containing essential amino acids activated the growth and survival mTOR complex 1 (mTORC1) signaling pathway. Notably, SLC15A3 specifically interacted with mTOR on the lysosome, boosting mTORC1 activity selectively in resistant lymphoma cells but not in parental cancer cells. Silencing SLC15A3 diminished mTORC1 activity and restored resistant lymphoma sensitivity to 6MP. Strikingly, resistant lymphomas, but not primary tumors, exhibited heightened sensitivity to the clinical mTOR inhibitor, rapamycin, in culture and in vivo. We extended these findings in human lymphoma biopsies, which revealed increased SLC15A3 expression following antimetabolite therapy. Together, our study uncovered a metabolic adaptation that fuels cancer resistance to nucleotide deficiency and positions the mTORC1 inhibitor, rapamycin, as a potential therapeutic strategy for transforming the management of chemotherapy-resistant lymphomas.
Authors
Haojun Yang, Vincenzo Andrea Zingaro, Kevin Boardman, Ashish Noronha, Ekin Guney, Lingru Xue, Saishma Hoigebazar, Isabelle Liu, Sohit Miglani, Siyu Chen, Hieu Vu, Kwun Wah Wen, Hao G. Nguyen, Hani Goodarzi, Ralph J. DeBerardinis, Davide Ruggero
Abstract
Resistance to antiangiogenics is a major challenge in cancer therapy. These agents can either normalize or exacerbate tumor vascular abnormality and hypoxia. The mechanisms of resistance remain unclear in the latter setting. By integrating data from mouse models and clinical trials, we showed that hypoxia-inducing anti-VEGF therapy upregulated programmed cell death ligand 1 (PD-L1), yet failed to sensitize tumors to PD-L1 blockade. Mechanistically, early hypoxic stress triggered epithelial osteopontin (SPP1) production, which recruited monocytes and skewed macrophages toward M2 states, suppressing T cell cytotoxicity. Pharmacological SPP1 depletion impeded the development of hypoxia, reduced M2 infiltration, restored T cell activity, and enabled synergy between antiangiogenics and anti–PD-L1. Genetic dissection — tumor-epithelial Spp1-KO grafts and bone marrow chimeras generated by lethal irradiation and reconstitution with Spp1–/– or WT hematopoietic donors — showed that myeloid SPP1 contributed only marginally compared with epithelial SPP1. These findings identified SPP1 as a central mediator of resistance to hypoxia-inducing antiangiogenics, contributed to a comprehensive model of antiangiogenic resistance, and supported SPP1-targeted strategies to personalize immunotherapy and antiangiogenic therapy according to tumor hypoxia.
Authors
Jose Luis Ruiz-Sepulveda, Maria J. Bueno, Silvana Mouron, Veronica Jimenez-Renard, Manuel Muñoz, Manuel Moradiellos, Leonardo D. Garma, Luis García-Jimeno, Adam W. Watson, Ghassan Mouneimne, Solip Park, Rebeca Jimeno, Miguel Quintela-Fandino
Abstract
Oral antibiotics can predispose to joint inflammation, but this phenomenon remains poorly understood. Here, we leverage mouse models of alphavirus-induced arthritis to investigate the roles of gut commensals, metabolites, and host immune mechanisms in promoting musculoskeletal inflammation. Mice treated with a short course of oral antibiotics exhibited worsened arthritis after chikungunya (CHIKV) or Mayaro virus infections. This phenotype was associated with loss of short-chain fatty acids (SCFAs), greater intestinal permeability, and activation of gut-associated immune cells and required TLR4 signaling, MyD88 expression, monocytes, antigen-specific and bystander CD4+ T cells, and proinflammatory cytokines. Administration of exogenous SCFAs or colonization of mice with bacterial species that generate SCFAs mitigated CHIKV-induced joint inflammation. scRNA-seq revealed that gut-derived SCFAs ameliorate the inflammatory phenotype of synovial CD4+ T cells, infiltrating monocytes, and resident osteoclast-like cells. Thus, antibiotic-triggered gut dysbiosis exacerbates alphavirus arthritis by shaping the inflammatory profile of both infiltrating and resident immune cells in joint tissues.
Authors
Fang R. Zhao, Maksim Kleverov, Emma S. Winkler, Russell B. Williams, Hana Janova, Lindsay Droit, Leran Wang, Ting-ting Li, Leah Heath, Ana Jung, Matthias Mack, Megan T. Baldridge, Thaddeus S. Stappenbeck, Larissa B. Thackray, Chyi-Song Hsieh, Scott A. Handley, Chun-Jun Guo, Michael A. Fischbach, Maxim N. Artyomov, Michael S. Diamond
Abstract
Cholesterol overload contributes to metabolic dysfunction–associated steatohepatitis (MASH) progression. One major pathway that limits hepatic cholesterol accumulation is export via VLDL secretion. While sterol regulatory element–binding protein (SREBP) activity is suppressed by insulin-induced gene 1 (INSIG1) under high sterol conditions, VLDL secretion nonetheless persists to prevent lipotoxicity and liver injury, presenting an unresolved paradox in cholesterol sensing and lipoprotein export. Here, we identified a cholesterol-responsive interaction between nuclear factor erythroid 2 related factor-1 (NFE2L1) and INSIG1 that preserved cholesterol homeostasis by sustaining VLDL secretion. Liver-specific NFE2L1 deletion elevated INSIG1 abundance, suppressed SREBP1 activation, and impaired VLDL secretion, leading to hepatic cholesterol accumulation and liver injury. Mechanistically, NFE2L1 bound to INSIG1 via its N-terminal homology box 2 (NHB2) domain; free cholesterol strengthened this interaction to promote INSIG1 degradation, thereby enabling SREBP1 activation and VLDL export. In NFE2L1-deficient mice, WT NFE2L1, but not a mutant NFE2L1 form unable to interact with INSIG1 (NHB2-deleted mutant, ΔNHB2), restored SREBP1 activity and VLDL secretion. Lipidomics analysis revealed that NFE2L1 deficiency reduced serum triglyceride composition, which was restored exclusively by WT NFE2L1. In a murine MASH model, NFE2L1 overexpression activated SREBP1/2, lowered hepatic cholesterol, and attenuated liver injury, inflammation, and fibrosis, without elevating atherogenic lipoproteins owing to compensatory LDL receptor upregulation. Together, these findings explain how VLDL secretion capacity was maintained under cholesterol excess and identify the NFE2L1/INSIG1 axis as a sterol-responsive safeguard for hepatic lipid homeostasis and a potential therapeutic target for MASH.
Authors
Shijun Deng, Jessica E. Freed, Grace Y. Lee, Gizel Askin, Zhe Cao, Özgür Cakici, Bo Yuan, Sheng Tony Hui, Karen E. Inouye, Isabel Graupera, Gökhan S. Hotamışlıgil
Abstract
Medulloblastoma (MB) is the most common malignant pediatric brain tumor. Current therapies are associated with substantial morbidity, and prognosis remains poor in high-risk subgroups, particularly those with TP53 mutations or relapsed disease. Cellular senescence is a tumor-suppressive program implicated in MB, but its role in antitumor immunity remains incompletely understood. We found that protein phosphatase 2A (PP2A) regulated immunogenic senescence in MB. Genetic ablation of the PP2A catalytic subunit PP2Ac or depletion of the regulatory subunit PP2A-B56α induced senescence in MB models. PP2Ac-deficient senescent cells exhibited increased MHC class I expression and enhanced immunogenicity. In syngeneic orthotopic models, PP2Ac loss prolonged survival in an immune- and CD8+ T cell–dependent manner. Analysis of patient datasets showed that senescence-associated gene signatures correlated with improved survival. Single-cell transcriptomic analysis further revealed that senescent MB cells were heterogeneous and that reduced PP2A activity was associated with an immunogenic senescence state. Because the PP2A inhibitor LB-100 has limited potency and off-target effects, we developed a lipid nanoparticle (LNP) platform to deliver siRNA targeting PPP2CA. LNP–small-interfering PP2Ac efficiently silenced PP2Ac in vitro and, when delivered locally in vivo, prolonged survival in a CD8+ T cell–dependent manner. Together, these findings identify PP2A as a regulator of immunogenic senescence in MB and support PP2Ac targeting as a therapeutic strategy.
Authors
Winson S. Ho, Isha Mondal, Jingjing Liu, Raymond Sun, Jiawei Huo, Chao Gao, Oishika Das, Daren Tieu, Jingqi Sun, Hanchen Lin, Peng Zhang, Jiyang Yu, Rongze Olivia Lu
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Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)