Research Article
Abstract
Defects in the early events of insulin biosynthesis, including inefficient preproinsulin (PPI) translocation across the membrane of the ER and proinsulin (PI) misfolding in the ER, can cause diabetes. Cellular machineries involved in these events remain poorly defined. Genes encoding translocon-associated protein α (TRAPα) show linkage to glycemic control in humans, though their pathophysiological role remains unknown. Here, we found that β cell–specific TRAPα-KO mice fed a chow diet or a high-fat diet (HFD) had decreased levels of circulating insulin, with age- and diet-related glucose intolerance. Multiple independent approaches revealed that TRAPα-KO not only causes inefficient PPI translocation but also leads to PI misfolding and ER stress, selectively limiting PI ER export and β cell compensatory potential. Importantly, decreased TRAPα expression was evident in islets of wild-type mice fed the HFD and in patients with type 2 diabetes (T2D). Furthermore, TRAPα expression was positively correlated with insulin content in human islet β cells, and decreased TRAPα was associated with PI maturation defects in T2D islets. Together, these data demonstrate that TRAPα deficiency in pancreatic β cells impairs PPI translocation, PI folding, insulin production, and glucose homeostasis, contributing to its genetic linkage to T2D.
Authors
Xin Li, Jingxin Hu, Yumeng Huang, Hai Zhang, Ning Xu, Yang Liu, Xuan Liu, Yuanyuan Ye, Xinxin Zhang, Xiaoxi Xu, Yuxin Fan, Ziyue Zhang, Weiping J. Zhang, Shusen Wang, Wenli Feng, Peter Arvan, Ming Liu
Abstract
The N-Myc gene MYCN amplification accounts for the most common genetic aberration in neuroblastoma and strongly predicts the aggressive progression and poor clinical prognosis. However, clinically effective therapies that directly target N-Myc activity are limited. N-Myc is a transcription factor, and its stability is tightly controlled by ubiquitination-dependent proteasomal degradation. Here, we discovered that Kelch-like protein 37 (KLHL37) played a crucial role in enhancing the protein stability of N-Myc in neuroblastoma. KLHL37 directly interacted with N-Myc to disrupt N-Myc–FBXW7 interaction, thereby stabilizing N-Myc and enabling tumor progression. Suppressing KLHL37 effectively induced the degradation of N-Myc and had a profound inhibitory effect on the growth of MYCN-amplified neuroblastoma. Notably, we identified RTA-408 as an inhibitor of KLHL37 to disrupt the KLHL37–N-Myc complex, promoting the degradation of N-Myc and suppressing neuroblastoma in vivo and in vitro. Moreover, we elucidated the therapeutic potential of RTA-408 for neuroblastoma using patient-derived neuroblastoma cell and patient-derived xenograft tumor models. RTA408’s antitumor effects may not occur exclusively via KLHL37, and specific KLHL37 inhibitors are expected to be developed in the future. These findings not only uncover the biological function of KLHL37 in regulating N-Myc stability, but also indicate that KLHL37 inhibition is a promising therapeutic regimen for neuroblastoma, especially in patients with MYCN-amplified tumors.
Authors
Senfeng Xiang, Pengfei Chen, Xiaoxian Shi, Hanqi Cai, Zihan Shen, Luyang Liu, Aixiao Xu, Jianhua Zhang, Xingya Zhang, Shaowei Bing, Jinhu Wang, Xuejing Shao, Ji Cao, Bo Yang, Qiaojun He, Meidan Ying
Abstract
Immune and clinical outcomes to Mycobacterium tuberculosis (Mtb) infection vary greatly between individuals, yet the underlying genetic and cellular mechanisms driving this heterogeneity remain poorly understood. We performed a cellular genome-wide association study to identify genetic variants associated with Mtb-induced monocyte transcriptional expression of IL1B, IL6, TNF, and IFNB1 via RNA-Seq in a Ugandan cohort. Significantly associated variants were assessed for transferability in an independent Seattle cohort, further validated in vitro, and assessed for clinical phenotype associations. We identified 77 loci suggestively associated with Mtb-induced cytokine expression in monocytes in Uganda. SNPs associated with Mtb-induced TNF were enriched within α-linolenic acid metabolism pathway genes, which was validated in vitro using PLA2 inhibitors. Four loci maintained significant associations in Seattle. We validated a cytokine effect with siRNA knockdown for two of these loci, which mapped to the genes SLIT3 and SLC1A1. Furthermore, exogenous treatment of macrophages with SLIT3 enhanced Mtb intracellular replication. Finally, SLC1A1 and SLIT3 variants were associated with susceptibility to tuberculous meningitis and subsequent survival, respectively, in a Vietnamese cohort. In summary, we identified multiple variants and pathways associated with Mtb-induced cytokine transcriptional responses that were validated in vitro and were associated with clinical tuberculosis susceptibility.
Authors
Joshua J. Ivie, Kimberly A. Dill-McFarland, Jason D. Simmons, Glenna J. Peterson, Penelope H. Benchek, Harriet Mayanja-Kizza, Lily E. Veith, Moeko Agata, Dang T.M. Ha, Ho D.T. Nghia, W. Henry Boom, Catherine M. Stein, Chiea C. Khor, Guy E. Thwaites, Hoang T. Hai, Nguyen T.T. Thuong, Xuling Chang, Sarah J. Dunstan, Thomas R. Hawn
Abstract
Air pollution is a serious environmental threat to public health; however, the molecular basis underlying its detrimental effects on respiratory fitness remains poorly understood. Here, we showed that exposure to particulate matter ≤ 2.5 μm (PM2.5), a substantial fraction of air pollutants, induced the generation of reactive aldehyde species in the airway. We identified aldehyde dehydrogenase 1A1 (ALDH1A1), which was selectively expressed in airway epithelium, as an enzyme responsible for detoxifying these reactive aldehyde species. Loss of ALDH1A1 function resulted in the accumulation of aldehyde adducts in the airway, which selectively impaired mucociliary clearance (MCC), a critical defense mechanism against respiratory pathogens. Thus, ALDH1A1-deficient mice pre-exposed to PM2.5 exhibited increased susceptibility to pneumonia. Conversely, pharmacological enhancement of ALDH1A1 activity promoted the restoration of MCC function. These findings elucidate the critical role of aldehyde metabolism in protecting against PM2.5 exposure, offering a potential target to mitigate the negative health consequences of air pollution.
Authors
Noriko Shinjyo, Haruna Kimura, Tomomi Yoshihara, Jun Suzuki, Masaya Yamaguchi, Shigetada Kawabata, Yasutaka Okabe
Abstract
Poly(ADP-ribose) polymerase (PARP) inhibitors (PARPis) are used to treat BRCA-mutated (BRCAm) cancer patients; however, resistance has been observed. Therefore, biomarkers to indicate PARPi resistance and combination therapy to overcome that are urgently needed. We identified a high prevalence of activated FGF receptor 3 (FGFR3) in BRCAm triple-negative breast cancer (TNBC) cells with intrinsic and acquired PARPi resistance. FGFR3 phosphorylated PARP1 at tyrosine 158 (Y158) to recruit BRG1 and prolong chromatin-loaded MRE11, thus promoting homologous recombination (HR) to enhance PARPi resistance. FGFR inhibition prolonged PARP trapping and synergized with PARPi in vitro and in vivo. High-level PARP1 Y158 phosphorylation (p-Y158) positively correlated with PARPi resistance in TNBC patient–derived xenograft models, and in PARPi-resistant TNBC patient tumors. These findings reveal that PARP1 p-Y158 facilitates BRG1-mediated HR to resolve the PARP-DNA complex, and PARP1 p-Y158 may indicate PARPi resistance that can be relieved by combining FGFR inhibitors (FGFRis) with PARPis. In summary, we show that FGFRi restores PARP trapping and PARPi antitumor efficacy in PARPi-resistant breast cancer by decreasing HR through the PARP1 p-Y158/BRG1/MER11 axis, suggesting that PARP1 p-Y158 is a biomarker for PARPi resistance that can be overcome by combining FGFRis with PARPis.
Authors
Mei-Kuang Chen, Hirohito Yamaguchi, Yuan Gao, Weiya Xia, Jeffrey T. Chang, Yu-Chun Hsiao, Tewodros W. Shegute, Zong-Shin Lin, Chen-Shiou Wu, Yu-Han Wang, Jennifer K. Litton, Qingqing Ding, Yongkun Wei, Yu-Yi Chu, Funda Meric-Bernstam, Helen Piwnica-Worms, Banu Arun, Jordi Rodon Ahnert, Jinsong Liu, Jun Yao, Wei-Chao Chang, Hung-Ling Wang, Coya Tapia, Constance T. Albarracin, Khandan Keyomarsi, Shao-Chun Wang, Ying-Nai Wang, Gabriel N. Hortobagyi, Chunru Lin, Liuqing Yang, Dihua Yu, Mien-Chie Hung
Abstract
Tryptophan hydroxylase (TPH) is a rate-limiting enzyme for serotonin or 5-hydroxytryptamine (5-HT) synthesis. Previously, adipocyte TPH1 has been linked to increased adipose 5-HT, reduced brown adipose tissue (BAT) thermogenesis, and obesity. However, the role of TPH2, a neural isoform highly expressed in obese adipose tissue, is unknown. Here, we report that adipose tissue expression of TPH2 is dramatically elevated in mice with diet-induced obesity (DIO) and ob/ob mice, as well as in obese humans. In mice fed a high-fat diet, adipocyte TPH2 deficiency improved DIO-induced metabolic complications, enhanced BAT thermogenesis, and increased intestinal energy-harvesting efficiency without affecting adiposity. Conversely, TPH2 overexpression in epididymal adipocytes of chow-fed mice raised adipose and plasma 5-HT levels, suppressed BAT thermogenesis, and exacerbated obesity and metabolic dysfunction. We found that obesity-induced hyperinsulinemia upregulated adipocyte TPH2 expression via activation of mechanistic target of rapamycin complex 1 and SREBP1. In humans, TPH2 mRNA levels in subcutaneous adipose tissue, but not those of TPH1, are positively correlated with fasting plasma insulin concentrations. In summary, our study demonstrates that obesity-associated increases in adipocyte TPH2 can regulate distal tissue physiology and energy metabolism, suggesting that TPH2 could be a potential therapeutic target for obesity and its associated complications.
Authors
Brian I. Park, Andrew R. Reeves, Ying Zhu, Robin A. Wilson, Sophia C. Fernandes, Kimberly K. Buhman, Kelli A. Lytle, Michael D. Jensen, Andrew S. Greenberg
Abstract
Abnormal expansions of the CAG trinucleotide repeat within specific gene exons give rise to polyglutamine (polyQ) diseases, a family of inherited disorders characterized by late-onset neurodegeneration. Recently, a new type of polyQ disease was identified and named spinocerebellar ataxia 51 (SCA51). SCA51 is caused by polyQ expansion in THAP domain containing 11 (THAP11), an essential transcription factor for brain development. The pathogenesis of SCA51, particularly how mutant THAP11 with polyQ expansion contributes to neuropathology, remains elusive. Our study of mouse and monkey brains revealed that THAP11 expression is subject to developmental regulation, showing enrichment in the cerebellum. However, knocking down endogenous THAP11 in adult mice did not affect neuronal survival. In contrast, expressing mutant THAP11 with polyQ expansion led to pronounced protein aggregation, cerebellar neurodegeneration, and motor deficits, indicating that gain-of-function mechanisms are central to SCA51 pathogenesis. We discovered activated microglia expressing triggering receptor expressed on myeloid cells 2 (TREM2) in the cerebellum of a newly developed SCA51 knockin mouse model. Mechanistically, mutant THAP11 enhanced the transcription of TREM2, leading to its upregulation. The loss of TREM2 or depletion of microglia mitigated neurodegeneration induced by mutant THAP11. Our study offers the first mechanistic insights to our knowledge into the pathogenesis of SCA51, highlighting the role of TREM2-mediated microglial activation in SCA51 neuropathology.
Authors
Eshu Ruan, Jingpan Lin, Zhao Chen, Qianai Sheng, Laiqiang Chen, Jiating He, Xuezhi Duan, Yiyang Qin, Tingting Xing, Sitong Yang, Mingtian Pan, Xiangyu Guo, Peng Yin, Xiao-Jiang Li, Hong Jiang, Shihua Li, Su Yang
Abstract
Mitral valve prolapse is often benign, but progression to mitral regurgitation may require invasive intervention and there is no specific medical therapy. An association of mitral valve prolapse with Marfan syndrome resulting from pathogenic FBN1 variants supports the use of hypomorphic fibrillin-1 mgR mice to investigate mechanisms and therapy for mitral valve disease. mgR mice developed severe myxomatous mitral valve degeneration with mitral regurgitation by 12 weeks of age. Persistent activation of TGF-β and mTOR signaling along with macrophage recruitment preceded histological changes at 4 weeks of age. Short-term mTOR inhibition with rapamycin from 4 to 5 weeks of age prevented TGF-β overactivity and leukocytic infiltrates, while long-term inhibition of mTOR or TGF-β signaling from 4 to 12 weeks of age rescued mitral valve leaflet degeneration. Transcriptomic analysis identified integrins as key receptors in signaling interactions, and serologic neutralization of integrin signaling or a chimeric integrin receptor altering signaling prevented mTOR activation. We confirmed increased mTOR signaling and a conserved transcriptome signature in human specimens of sporadic mitral valve prolapse. Thus, mTOR activation from abnormal integrin-dependent cell–matrix interactions drives TGF-β overactivity and myxomatous mitral valve degeneration, and mTOR inhibition may prevent disease progression of mitral valve prolapse.
Authors
Fu Gao, Qixin Chen, Makoto Mori, Sufang Li, Giovanni Ferrari, Markus Krane, Rong Fan, George Tellides, Yang Liu, Arnar Geirsson
Abstract
Graft endothelial cells (ECs) express donor alloantigens and encounter cytotoxic T lymphocytes (CTLs) but are generally spared during T cell–mediated rejection (TCMR), which predominantly affects epithelial structures. The mechanisms underlying this vascular immune privilege are unclear. Transcriptomics analyses and endothelial-mesenchymal transition assessments confirmed that the graft endothelium was preserved during TCMR. Coculture experiments revealed that endothelial and epithelial cells were equally susceptible to CTL-mediated lysis, ruling out cell-intrinsic protection. Intravital microscopy of murine kidney grafts and single-cell RNA-Seq of human renal allografts demonstrated that CTL interactions with ECs were transient compared with epithelial cells. This disparity was mediated by a chemotactic gradient produced by graft stromal cells, guiding CTLs away from ECs toward epithelial targets. In vitro, chemotaxis overrode T cell receptor–induced cytotoxicity, preventing endothelial damage. Finally, analysis of TCMR biopsies revealed that disruption of the chemotactic gradient correlated with endothelialitis lesions, linking its loss to vascular damage. These findings challenge the traditional view of cell-intrinsic immune privilege, proposing a cell-extrinsic mechanism, in which chemotaxis preserves graft vasculature during TCMR. This mechanism may have implications beyond transplantation, highlighting its role in maintaining vascular integrity across pathological conditions.
Authors
Thomas Barba, Martin Oberbarnscheidt, Gregory Franck, Chantal Gao, Sebastien This, Maud Rabeyrin, Candice Roufosse, Linda Moran, Alice Koenig, Virginie Mathias, Carole Saison, Valérie Dubois, Nicolas Pallet, Dany Anglicheau, Baptiste Lamarthée, Alexandre Hertig, Emmanuel Morelon, Arnaud Hot, Helena Paidassi, Thierry Defrance, Antonio Nicoletti, Jean-Paul Duong Van Huyen, Yi-Chung Xu-Dubois, Faddi G. Lakkis, Olivier Thaunat
Abstract
Lung cancer is the leading cause of cancer mortality among people with HIV (PWH), with increased incidence and poor outcomes. This study explored whether the tumor microenvironment (TME) of HIV-associated non–small cell lung cancer (NSCLC) limits tumor-specific immune responses. With a matched cohort of NSCLC samples from PWH and from people without HIV (PWOH), we used imaging mass cytometry, a linear mixed-effects model, and an artificial intelligence–based (AI-based) PageRank mathematical algorithm based on spectral graph theory to demonstrate that HIV-associated tumors have differential distribution of tumor-infiltrating CD8+ and CD4+ T cells, enriched for the expression of programmed cell death 1 (PD-1) and lymphocyte-activating gene 3 (LAG3), as well as activation and proliferation markers. We also demonstrate higher expression of immunoregulatory molecules (PD-L1, PD-L2, B7-H3, B7-H4, IDO1, and VISTA) among tumor-associated macrophages. Discrimination of cells between tumors from PWH versus those from PWOH was confirmed by spectral graph theory with 84.6% accuracy. Furthermore, we noted differences in spatial orientation of immune cells within the TME of PWH compared with PWOH. Additionally, cells from PWH, compared with those from PWOH, exhibited decreased tumor killing when exposed to HLA-matched NSCLC cell lines. In conclusion, our study demonstrates that the HIV-associated TME sustained a unique immune landscape, showing evidence of immune cells with enhanced immunoregulatory phenotypes and impaired antitumor responses, with implications for responses to immune checkpoint blocker therapies.
Authors
Shruti S. Desai, Syim Salahuddin, Ramsey Yusuf, Kishu Ranjan, Jianlei Gu, Lais Osmani, Ya-Wei Lin, Sameet Mehta, Ronan Talmon, Insoo Kang, Yuval Kluger, Hongyu Zhao, Kurt Schalper, Brinda Emu
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ISSN: 0021-9738 (print), 1558-8238 (online)