Fassihi et al. and Nakazawa et al. report that a C-terminal deletion of the transcription factor TFIIH-p52 subunit (blue; C-terminus in white) causes xeroderma pigmentosum. The cover art was created using PyMOL. Image credit: Keiko Itano.
In pancreatic β-cells, misfolded proinsulin is a substrate for Endoplasmic Reticulum-Associated protein Degradation (ERAD) via HRD1/SEL1L. β-cell HRD1 activity is alternately reported to improve, or impair, insulin biogenesis. Further, while β-cell SEL1L deficiency causes HRD1 hypofunction and diminishes islet insulin content; reports conflict as to whether β-cell ERAD deficiency increases or decreases proinsulin levels. Here we’ve examined β-cell-specific Hrd1-KO mice (chronic deficiency), plus rodent (and human islet) β-cells treated acutely with HRD1 inhibitor. β-Hrd1-KO mice developed diabetes with decreased islet proinsulin yet a relative increase of misfolded proinsulin re-distributed to the ER; upregulated biochemical markers of β-cell ER stress and autophagy; electron microscopic evidence of ER enlargement and decreased insulin granule content; and increased glucagon-positive islet cells. Misfolded proinsulin was also increased in islets treated with inhibitors of lysosomal degradation. Preceding any loss of total proinsulin, acute HRD1 inhibition triggered increased nonnative proinsulin, increased phospho-eIF2ɑ with inhibited proinsulin synthesis, and increased LC3b-II (the abundance of which requires expression of SigmaR1). We posit a subset of proinsulin molecules undergoes HRD1-mediated disposal. When HRD1 is unavailable, misfolded proinsulin accumulates, accompanied by increased phospho-eIF2ɑ that limits further proinsulin synthesis, plus SigmaR1-dependent autophagy activation, ultimately lowering steady-state β-cell proinsulin (and insulin) levels — triggering diabetes.
Anoop Arunagiri, Leena Haataja, Maroof Alam, Noah F. Gleason, Emma Mastroianni, Chao-Yin Cheng, Sami Bazzi Onton, Jeffrey Knupp, Ibrahim Metawea, Anis Hassan, Dennis Larkin, Deyu Fang, Billy Tsai, Ling Qi, Peter Arvan
While immune checkpoint blockade (ICB) therapy has revolutionized the antitumor therapeutic landscape, it remains successful in only a small subset of cancer patients. Poor or loss of MHC-I expression has been implicated as a common mechanism of ICB resistance. Yet the molecular mechanisms underlying impaired MHC-I remain to be fully elucidated. Herein, we identified USP22 as a critical factor responsible for ICB resistance through suppressing MHC-I-mediated neoantigen presentation to CD8 T cells. Both genetic and pharmacologic USP22 inhibition increased immunogenicity and overcome anti-PD-1 immunotherapeutic resistance. At the molecular level, USP22 functions as a deubiquitinase for the methyltransferase EZH2, leading to transcriptional silencing of MHC-I gene expression. Targeted Usp22 inhibition resulted in increased tumoral MHC-I expression and consequently enhanced CD8 T cell killing, which was largely abrogated by Ezh2 reconstitution. Multiplexed immunofluorescence staining detected a strong reverse correlation between USP22 expression and both 2M expression and CD8+ T lymphocyte infiltration in solid tumors. Importantly, USP22 upregulation was associated with ICB immunotherapeutic resistance in patients with lung cancer. Collectively, this study highlights the role of USP22 as a diagnostic biomarker for ICB resistance and provides a potential therapeutic avenue to overcome the current ICB resistance through inhibition of USP22.
Kun Liu, Radhika Iyer, Yi Li, Jun Zhu, Zhaomeng Cai, Juncheng Wei, Yang Cheng, Amy Tang, Hai Wang, Qiong Gao, Nikita Lavanya Mani, Noah Marx, Beixue Gao, D. Martin Watterson, Seema A. Khan, William J. Gradishar, Huiping Liu, Deyu Fang
11-cis-Retinal is essential for light perception in mammalian photoreceptors (PRs), and aberrations in retinoid transformations cause severe retinal diseases. Understanding these processes is crucial for combating blinding diseases. The visual cycle, operating within PRs and the retinal pigment epithelium (RPE), regenerates 11-cis-retinal to sustain light sensitivity. Retinoids are also present in Müller glia (MG), hypothesized to supply 11-cis-retinol to cone PRs and retinal ganglion cells (RGCs). To trace retinoid movement through retinal cell types, we used cell-specific knock-in of lecithin:retinol acyltransferase (LRAT), which converts retinols into stable retinyl esters (REs). Ectopic LRAT expression in murine PRs, MG, and RGCs resulted in RE synthesis, with REs differing in abundance and isomeric composition across cell types under genetic and light-based perturbations. PR inner segments showed high 11-cis-RE content, suggesting a constant 11-cis-retinoid supply for pigment regeneration. In MG expressing LRAT, all-trans-REs were detected, contrasting with 11-cis-REs in PRs. The MG-specific LRAT phenotype mirrored the RE-rich human neural retina, suggesting human MG may utilize LRAT to maintain retinoid reservoirs. Our findings reveal tightly controlled retinoid flux throughout the mammalian retina supporting sustained vision, expanding understanding of the visual cycle to combat retinal diseases.
Zachary J. Engfer, Grazyna Palczewska, Samuel W. Du, Jianye Zhang, Zhiqian Dong, Carolline Rodrigues Menezes, Jun Wang, Jianming Shao, Budd A. Tucker, Robert F. Mullins, Rui Chen, Philip D. Kiser, Krzysztof Palczewski
N6-methyladenosine (m6A), the most predominant RNA modification in humans, participates in various fundamental and pathological bioprocesses. Dynamic manipulation of m6A deposition in the transcriptome is critical for cancer progression, while how this regulation is achieved remains understudied. Here, we report that in prostate cancer (PCa), Polycomb group (PcG) protein Enhancer of Zeste Homolog 2 (EZH2) exerts an additional function in m6A regulation via its enzymatic activity. Mechanistically, EZH2 methylates and stabilizes FOXA1 proteins from degradation, which in turn facilitates the transcription of m6A reader YTHDF1. Through activating an m6A autoregulation pathway, YTHDF1 enhances the translation of METTL14 and WTAP, two critical components of the m6A methyltransferase complex (MTC), and thereby upregulates the global m6A level in PCa cells. We further demonstrate that inhibiting the catalytic activity of EZH2 suppresses the translation process globally through targeting the YTHDF1-m6A axis. By disrupting both the expression and interaction of key m6A MTC subunits, combinational treatment of EZH2 degrader MS8815 and m6A inhibitor STM2457 mitigates prostate tumor growth synergistically. Together, our study decodes a previously hidden interrelationship between EZH2 and mRNA modification, which may be leveraged to advance the EZH2-targeting curative strategies in cancer.
Yang Yi, Joshua Fry, Chaehyun Yum, Rui Wang, Siqi Wu, Sharath Narayan, Qi Liu, Xingxing Zhang, Htoo Zarni Oo, Ning Xie, Yanqiang Li, Xinlei Gao, Xufen Yu, Xiaoping Hu, Qiaqia Li, Kemal Keseroglu, Ertuğrul M. Özbudak, Sarki A. Abdulkadir, Kaifu Chen, Jian Jin, Jonathan C. Zhao, Xuesen Dong, Daniel Arango, Rendong Yang, Qi Cao
Clonal hematopoiesis due to TET2-driver mutations (CH) is associated with coronary heart disease and worse prognosis among patients with aortic valve stenosis (AVS). However, it is unknown what role CH plays in the pathogenesis of AVS. In a meta-analysis of All Of Us, BioVU, and the UK Biobank, patients with CHIP exhibited an increased risk of AVS, with a higher risk among patients with TET2 or ASXL1 mutations. Single-cell RNA-sequencing of immune cells from AVS patients harboring TET2 CH-driver mutations revealed monocytes with heightened pro-inflammatory signatures and increased expression of pro-calcific paracrine signaling factors, most notably Oncostatin M (OSM). Secreted factors from TET2-silenced macrophages increased in vitro calcium deposition by mesenchymal cells, which was ablated by OSM silencing. Atheroprone Ldlr–/– mice receiving CH-mimicking Tet2–/– bone marrow transplants displayed greater calcium deposition in aortic valves. Together, these results demonstrate that monocytes with CH promote aortic valve calcification, and that patients with CH are at increased risk of AVS.
Wesley T. Abplanalp, Michael A. Raddatz, Bianca Schuhmacher, Silvia Mas-Peiro, María A. Zuriaga, Nuria Matesanz, José J. Fuster, Yash Pershad, Caitlyn Vlasschaert, Alexander J. Silver, Eric H. Farber-Eger, Yaomin Xu, Quinn S. Wells, Delara Shahidi, Sameen Fatima, Xiao Yang, Adwitiya A.P. Boruah, Akshay Ware, Maximilian Merten, Moritz von Scheidt, David John, Mariana Shumliakivska, Marion Muhly-Reinholz, Mariuca Vasa-Nicotera, Stefan Guenter, Michael R. Savona, Brian R. Lindman, Stefanie Dimmeler, Alexander G. Bick, Andreas M. Zeiher
Therapies targeting the glucagon-like peptide 1 (GLP-1) receptor have revolutionized the treatment of obesity and diabetes. This series of reviews, curated by Dr. Dan Drucker, describes the latest research in this fast-moving in field, from our evolving understanding of the mechanism of GLP-1 receptor signaling to the medicines’ impact on inflammation and the consequences for heart, kidney, and brain health. The reviews also explore the impact of these medicines on conditions beyond their initial indications, including cancer and neurodegenerative disease risk.
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In this episode, Marie Jeansson explains how the paper's findings suggest that TIE2 activation via angiopoietin-2 (ANGPT2)-binding and TIE2-activating antibody warrants investigation as a therapy in human CKD...