Cell biology
Abstract
Diabetic retinopathy features early glial stress and neurovascular dysfunction, yet Müller glial programs linking inflammatory cues to oxidative injury remain unclear. We identify a spatially clustered interferon-stimulated gene 15 (ISG15)+ Müller glial subtype expanded in streptozotocin-induced diabetic mice. High glucose alone did not increase basal free ISG15 or detectable ISGylation (ISG15-dependent protein modification) in primary Müller glia, whereas conditioned medium from high glucose–exposed microglia induced both, recapitulated by IFN-β and attenuated by type I interferon receptor 1 inhibition. In vivo, Ifnb1 RNAscope signals were associated with microglia, retinal Ifnb1 expression increased in diabetic retinas, and microglial depletion reduced Ifnb1 expression and limited the expansion of ISG15+ Müller glia. Müller glia–specific Isg15 deletion preserved blood–retinal barrier integrity, reduced acellular capillaries and Evans blue leakage, and mitigated oxidative stress, lipid peroxidation, and glutathione redox imbalance. Loss of ISG15 or disruption of ISGylation blunted interferon-driven oxidative stress in Müller glia and reduced Müller glia–conditioned medium–dependent endothelial migration and tube formation. Mechanistically, IFN-β promoted peroxiredoxin 6 (PRDX6) ISGylation and proteasome-dependent degradation without altering Prdx6 transcripts. Thus, microglial IFN-β promotes an ISG15+ Müller glial subtype that compromises antioxidant defense and promotes early barrier injury in diabetic retinopathy.
Authors
Tian Niu, Yan Jiang, Xindan Xing, Qian Zhu, Xinyi Liu, Kangjia Lv, Junwei Fang, Kun Liu
Abstract
Osteoarthritis (OA) is the most common degenerative joint disease. However, the molecular mechanisms underlying OA-induced cartilage degeneration remain elusive. Here, we identify IFN regulatory factor 2 binding protein 2 (IRF2BP2) as an important regulator of chondrocyte differentiation and articular cartilage regeneration. Irf2bp2 deficiency promoted chondrogenesis and inhibited chondrocyte terminal differentiation by transcriptionally upregulating the key chondrogenic marker SRY-box transcription factor 9 (SOX9), inducing its ectopic expression in the hypertrophic zone. Cartilage-specific KO of Irf2bp2 elevated SOX9 levels, attenuated OA progression in the destabilization of the medial meniscus (DMM) model, and enhanced cartilage regeneration and hyalinization in the microfracture model. Mechanistically, IRF2BP2 bound to and stabilized Fos-related antigen 2 (FOSL2), an activator protein 1 (AP-1) family member, thereby facilitating FOSL2/c-Jun complex formation and repressing SOX9 expression. Adeno-associated virus–mediated (AAV-mediated) FOSL2 overexpression reversed the protective phenotype observed in Irf2bp2-deficient mice. These findings establish the Hippo/IRF2BP2/FOSL2/SOX9 regulatory axis as critical for cartilage regeneration. Importantly, AAV-mediated IRF2BP2 knockdown, pharmacological targeting of the IRF2BP2/AP-1 axis using T-5224, and delivery of a peptide that disrupts IRF2BP2-FOSL2 binding via intra-articular injection all preserved cartilage integrity, offering potential therapeutic strategies for OA and cartilage regeneration.
Authors
Hao Zhou, Tiantian Lu, Zhuoqun Gao, Can Cui, Zhiqiang Fang, Yu You, Jing Jiang, Jinjin Xu, Fang Wei, Jing Yu, Hu Zhou, Jinsong Li, Jian Luo, Lei Zhang, Yunyun Jin
Abstract
BACKGROUND We previously defined 4 hormone receptor+/human epidermal growth factor receptor 2– (HR+/HER2–) subtypes: SNF1 canonical luminal, SNF2 immunogenic, SNF3 proliferative, and SNF4 RTK driven. The FASCINATE-N proof-of-concept trial demonstrated that subtyping-directed precision treatment improves pathologic complete response in locally advanced HR+/HER2– breast cancer, yet efficacy remains suboptimal.METHODS We integrated transcriptomic, genomic, digital pathology, and clinical data from this trial (n = 230) and focused on exceptional responders to explore opportunities for refining treatment strategies.RESULTS In SNF1, we uncovered that perineural invasion diminished endocrine therapy efficacy, suggesting the potential benefit of incorporating perineural blockade. Digital pathology and spatial transcriptomics identified that the spatial architecture of the tumor-stromal-immune interface influenced apatinib efficacy in SNF4, highlighting the importance of interfering with the tumor microenvironment. In the SNF3 group, exceptionally well responders exhibited multiple mutations in DNA repair genes and cell cycle activation, correlating with the efficacy of poly (ADP-ribose) polymerase and CDK4/6 inhibitors. Additionally, we illustrated that lymphatic vessel infiltration was linked to improved immunotherapy outcomes in HR+/HER2– SNF2 tumors.CONCLUSION Overall, our study emphasizes the importance of multimodal assessments in optimizing precision treatments for HR+/HER2– breast cancer.FUNDING National Natural Science Foundation of China, grant numbers U25C2032, 82441028, and 82573645; The Shanghai Key Laboratory of Breast Cancer, grant number 12DZ2260100; The Human Phenome Data Center of Fudan University.TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT05582499.
Authors
Yi Xiao, Fan Yang, Ying-Jia Qi, Li Chen, Hang Zhang, Si-Wei Zhang, Rui Shan, Liang Huang, Jun-Jie Li, Yi-Zhou Jiang, Zhi-Ming Shao
Abstract
Friedreich’s ataxia (FRDA) is a multisystemic neurodegenerative disorder caused by GAA repeat expansion in intron 1 of frataxin (FXN), resulting in FXN deficiency and mitochondrial dysfunction. Current therapies do not correct the underlying genetic defect. Here, we demonstrate that ex vivo CRISPR/Cas9 excision of the GAA expansion in hematopoietic stem and progenitor cells (HSPCs) provides durable, systemic therapy for FRDA. A single infusion of gene-edited Sca1+ HSPCs, mPPL-001, into myeloablative, humanized YG8JR mice resulted in long-term engraftment of donor-derived cells across hematopoietic and FRDA-affected tissues. mPPL-001 increased FXN expression and corrected multiple key pathogenic drivers of FRDA, including mitochondrial stress, microglial and macrophage activation, and inflammatory signaling. These coordinated effects improved motor functions, preserved cerebellar architecture, mitigated cardiac pathology, and promoted survival of insulin-producing β cells in the pancreatic islets of Langerhans. Collectively, these findings establish FXN-edited autologous HSPCs as a one-time, disease-modifying therapy for FRDA and support advancement toward a first-in-human trial.
Authors
Anusha Sivakumar, Alexis N. Corl, Keneth Jordan Muñoz, Subhashini Arumugam, Betul B. Gunes, Angelyn B. Solis, Rishika Murthy, Lilas Rony El-Hachem, Donald P. Pizzo, Ian A. Blair, Teerapat Rojsajjakul, Clementina Mesaros, Xinlong Wan, Joseph N. Rainaldi, Rafael A. Badell-Grau, Veenita Khare, Kevin Eric Thai, Kavya Biederman, Stephanie Cherqui
Abstract
Insulin signaling is a critical determinant of metabolic health, and impairments in insulin action contribute to the development of type 2 diabetes. The kinase Akt is a central mediator of insulin signaling and is required for insulin’s suppression of hepatic glucose output. Although the regulation of Akt by the insulin receptor-PI3K pathway is well understood, there are instances in which signaling downstream of Akt is dissociated from proximal insulin signaling, for example in insulin resistance. Nonetheless, little is known about PI3K-independent mechanisms of Akt regulation. Here, we discovered that hepatocyte manganese concentrations are a key determinant of PI3K-independent Akt function in vivo. We further demonstrated that manganese increases Akt’s catalytic efficiency, and quantitative phosphoproteomics revealed that manganese and insulin act additively to enhance Akt activity. Moreover, we uncovered that hepatic manganese concentrations fluctuate during fasting and feeding via carbohydrate-dependent transcriptional regulation of the manganese efflux transporter Slc30a10. This dynamic metal–signaling axis provides a mechanistic link between nutrient status and Akt activation, and suggests a molecular explanation for the glucose-lowering effects of manganese observed in humans. Our findings establish manganese as a physiologically regulated cofactor for Akt and position metal bioavailability as a previously unrecognized layer of insulin signaling control.
Authors
Jennifer R. Gamarra, Sei Higuchi, Timothy L. Yuan, Yuke Xie, Cong Liu, Niroshan Shanmugarajah, Hang Yang, Meredith O. Kelly, Sarah A. Hannou, Kathrin Schilling, Ana Navas-Acien, Eunhee Choi, Anum Glasgow, Inna I. Astapova, Mark A. Herman, Rebecca A. Haeusler
Abstract
Triple negaJve breast cancer (TNBC) is characterised by poor prognosis and limited treatment opJons, parJally due to therapy-resistant stem/progenitor cells driving metastasis. Elevated expression of the transcripJon factor MYBL2 is associated with aggressive disease, yet its role in BC stem/progenitor cells remains elusive. Here, we employed inducible MYBL2 downregulaJon in TNBC cell lines and paJent-derived models to invesJgate its funcJon and idenJfy potenJal vulnerabiliJes associated with its high expression. Our funcJonal and mechanisJc analyses reveal that high MYBL2 levels are criJcal for stem cell self-renewal, DNA repair, and replicaJon stress response and lowering MYBL2 impairs stemness and self-renewal both in vitro and in vivo. Accordingly, high-MYBL2 stem/progenitor cells exhibit increased sensiJvity to Polθ inhibitors which is lost upon MYBL2 downregulaJon due to transcripJonal suppression. Combining Polθ inhibitors with ATR inhibitors further enhances this sensiJvity, in vitro, ex vivo and in vivo. These findings suggest that dual Polθ/ATR inhibiJon represents a promising therapeuJc strategy to target TNBC stem/progenitor cells with high MYBL2 expression, highlighJng MYBL2 as a potenJal biomarker to straJfy paJents for Polθ inhibitor-based therapies in TNBC.
Authors
Rachel Bayley, Xiaoping Qu, Adrija Chakraborty, Menna Shamma, Ciara Ward, Kinga Koscielniak, Anna Munsey, Suman Ahmed, Amber Stiby, Bohdana-Myroslava Briantseva, Kirendeep Jawanda, Christopher J. Lord, Abeer M. Shaaban, Marco Saponaro, Graeme C. M. Smith, Robert B. Clarke, Clare Davies, Paloma Garcia
Abstract
Splenic myelopoiesis supplies immunosuppressive myeloid cells in cancer, yet its local regulation remains unclear. Here we identify a self-amplifying circuit between neutrophils and hematopoietic stem and progenitor cells (HSPCs) that sustains splenic myelopoiesis. Tumor-associated neutrophils produced reactive oxygen species (ROS) and created an oxidatively stressed milieu in the spleen, which activated FOXO1 in neighboring HSPCs and drove DRP1-mediated mitochondrial fission, reprogramming HSPCs toward myeloid-biased expansion and immunosuppressive output. Progeny neutrophils reinforced splenic oxidative stress and perpetuated this loop. Genetic ablation of Cybb or spleen-targeted ROS scavenging inhibited FOXO1 activation and preserved fused mitochondria morphology in HSPCs. Consistently, blockade of FOXO1 or DRP1 prevented mitochondrial fission and reduced ROS-producing myeloid cell generation. Such interventions reduced splenic myelopoiesis, curtailed the production of suppressive myeloid cells in the spleen and their infiltration into tumors, and enhanced cytotoxic T cell activity, thereby restoring antitumor immunity and restraining tumor progression. Analyses of spleen samples from cancer patients, together with cord-blood HSPC and neutrophil co-culture experiments, support the human relevance of this neutrophil–ROS–HSPC axis. These findings reveal a self-propagating neutrophil–HSPC feedback circuit that locally sustains tumor-promoting splenic myelopoiesis and provide a rationale for targeting neutrophil-to-progenitor signaling to normalize antitumor immunity.
Authors
Lan Zhu, Shufeng Luo, Qiaomin Hua, Chang-An Zhao, Huiling Lin, Mingyu Liu, Lingyan Zhu, Jiabin Zheng, Huolun Feng, Yong Li, Chong Wu, Limin Zheng
Abstract
During organogenesis, stem cells undergo cellular and metabolic remodelling, facilitated by autophagy-mediated turnover of organelles. Autophagy impairment has been linked to human diseases, including neurodevelopmental disorders associated with disrupted neural stem/precursor cell (NPC) homeostasis, but the underlying mechanisms and pathogenic processes governing these connections remain poorly understood. Here, we report three de novo variants of uncertain significance (p.Gly223Asp, p.Gly889Glu, p.Met978Val) in the deubiquitinase USP15 in human probands with diverse clinical features, including a spectrum of brain malformations and metabolic phenotypes. Proband variants differentially altered USP15 activity and nucleocytoplasmic localization. USP15 showed dynamic localization in NPCs of embryonic mouse cerebral cortex. Using a knock-in mouse model carrying the p.Met978Val variant, we showed that aberrant cytoplasmic accumulation of USP15, but not its loss-of-function, impaired NPC self-renewal and differentiation, leading to reduced neuronal output and enlarged lateral ventricles. Mechanistically, USP15 deubiquitinated autophagy regulator ATG16L1, impeded its normal turnover, and impaired autophagy. Concurrently, lipid droplet mobilization and mitochondrial dynamics were attenuated. Reestablishing the ubiquitination-deubiquitination balance restored autophagy activity and normal neurogenesis. Our findings suggest that nucleocytoplasmic shuttling of USP15 creates a switch-like autophagy signal controlling NPC homeostasis, and its disruption may contribute to the pathogenesis of complex neurodevelopmental conditions.
Authors
Kaylan M.L. Burns, Mashiat Zaman, Daniel Young, Michelle Hua, Yu-Yun Gao, Yvonne Yan Yan Or, Farzaneh Nobakht, Bryn D. Webb, Julie A. Jurgens, Francis Ramond, Xing-Chang Wei, Caroline D. Robson, Alistair T. Pagnamenta, Marvel Megaly, Belal Tafech, Antoine Dufour, Timothy E. Shutt, Ping Yee Billie Au, Guang Yang
Abstract
γ-Secretase is a transmembrane protease complex that cleaves multiple type I transmembrane proteins, including amyloid precursor protein and neurogenic locus notch homolog protein (NOTCH). Although numerous γ-secretase inhibitors and modulators targeting Notch-dependent cancers have been developed in recent decades, their clinical translation has been hampered by low substrate specificity and on-target gut toxicity. Using a proteomics-based screening approach, we identified dedicator of cytokinesis protein 2 (DOCK2) as an interactor of the γ-secretase subunit nicastrin (NCSTN). We further demonstrate that DOCK2 regulates mannosylation of NCSTN N-glycans, which in turn modulates γ-secretase activity toward NOTCH receptors. Both genetic depletion of DOCK2 and pharmacological inhibition of NCSTN mannosylation with kifunensine attenuated Notch-dependent leukemia progression in vivo. Collectively, these findings uncover a regulatory mechanism underlying substrate-specific activation of γ-secretase and suggest a promising therapeutic strategy for Notch-related diseases.
Authors
Hua Jiang, Weixiang Bian, Yanjun Cao, Zhuo Zhang, Yijia Chen, Yue Sui, Hongqiang Qin, Xu Li
Abstract
Distress sharing within an ingroup instinctively motivates caregiving-like prosocial behavior in social animals and humans, yet how aversive social stimuli paradoxically trigger such behavior remains unclear. Here, we show that stress-state matching in observer mice elicits caregiving-like behaviors (allogrooming and injury-targeted allolicking) toward cagemates in pain, resulting in synchronized social buffering. Importantly, we identify that the excitation of vasopressin receptor 1a–expressing (V1aR-expressing) neurons in the central medial amygdala (CeM) underlies both emotional-state matching and subsequent allogrooming/allolicking. This excitation is accomplished by arginine vasopressin (AVP) release from presynaptic terminals of the hypothalamic paraventricular nucleus (PVN) to act specifically on postsynaptic V1aR in the CeM. The CeMV1aR neurons then project to the ventral tegmental area (VTA) to drive caregiving-like actions through positive reinforcement, manifested as prosocial preference and recurrent allogrooming/allolicking, and to produce anxiolysis in the caregiver. Collectively, we unravel a dedicated trisynaptic PVNAVP-CeMV1aR-VTA circuit driving and gating caregiving-like behaviors and advance the mechanistic understanding of AVP-V1aR signaling in prosociality.
Authors
Kai-Wen Geng, Rui-Rui Wang, Yan Yang, Yan Wang, Ting He, Chun-Li Li, Chong-Shun Xu, Jun Chen
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ISSN: 0021-9738 (print), 1558-8238 (online)