Cell biology
Abstract
GATA6 is a master regulator of differentiation in the pancreas and its expression levels determine the two main molecular subtypes of pancreatic cancer. High GATA6 contributes to the “classical” pancreatic cancer subtype, which is associated with a higher degree of tumor differentiation and better disease prognosis. However, why GATA6 expression varies across pancreatic cancers and what regulate GATA6 expression remain elusive. Here we report that the oncogenic KRAS-activated ERK signaling suppresses GATA6 transcription in pancreatic cancers. GATA6 mRNA levels inversely correlated with KRAS/ERK activity in pancreatic tumors. A genome-wide CRISPR screen in a GATA6-EGFP reporter knockin cell line identified JUNB as the ERK-regulated transcriptional repressor for GATA6. Active ERK stabilizes JUNB protein while KRAS/ERK inhibition led to ubiquitin-independent proteasomal degradation of JUNB and increased transcription of GATA6. Up-regulation of GATA6 enhanced chemosensitivity of pancreatic cancer cells and KRAS/ERK inhibitors synergized with chemotherapy in a GATA6-dependent manner. Our study identifies how oncogenic KRAS/ERK signaling suppresses GATA6 to cause dedifferentiation in pancreatic cancer. Combining KRAS/ERK inhibitors with standard-of-care chemotherapies could be a promising therapeutic strategy for treating pancreatic cancers.
Authors
Zheng Zhong, Xinang Cao, Pei-Ju Liao, Raman Sethi, Jeffrey A. Klomp, Clint A. Stalnecker, Jinmiao Chen, Yue Wan, Channing J. Der, David M. Virshup
Abstract
Emerging evidence demonstrates that chronic stress alters immunological, neurochemical and endocrinological functions, thereby promoting tumor progression. However, the underlying metabolic mechanism of chronic stress in tumor progression is still elusive. Using multi-omics analysis, we found that aminopeptidase N (ANPEP) was upregulated in tumors with chronic restraint, associating with the reprogramming of amino acid metabolism. Functional assays revealed that ANPEP promoted liver cancer growth and metastasis. Knockdown of ANPEP blocked chronic stress-induced liver cancer progression. Chronic stress-induced glucocorticoids promoted nuclear receptor subfamily 3 group C member 1 (NR3C1) nuclear translocation to activate ANPEP transcription by directly binding to its promoter. Furthermore, ANPEP promotes glutathione synthesis, subsequently inhibiting reactive oxygen species (ROS)-induced ferroptosis. Mechanistically, ANPEP interacted with solute carrier family 3 member 2 (SLC3A2) to block membrane associated ring-CH-type finger 8-mediated (MARCH8-mediated) lysosome-dependent degradation of SLC3A2, promoting intracellular L-cystine transport, thereby increasing glutathione synthesis. The combination of ANPEP silencing and sorafenib treatment showed a synergistic effect in inhibiting liver cancer progression. Finally, clinical data and mouse models demonstrated that chronic stress drove liver tumor progression via ANPEP-regulated SLC3A2. These findings reveal unanticipated communication between chronic stress and metabolic reprogramming during liver cancer progression, providing potential therapeutic implications for liver cancer.
Authors
Yongkang Wu, Yankun Zhang, Xiaojia Shi, Mengting Wu, Min Sun, Ying Feng, Wenmeng Ma, Xiule Jiang, Dingqi Fei, Mingjian Zhao, Zhuanchang Wu, Chunyang Li, Xiaohong Liang, Lifen Gao, Chunhong Ma, Xuetian Yue
Abstract
The efficacy of anticancer treatments, including radiotherapy, depends on the activation of type I IFN signaling. However, its regulatory networks and mechanisms remain to be elucidated. Here, we report that tumor cell–intrinsic type I IFN signaling can be transferred to macrophages via secretory autophagy, inducing CXCL9hi macrophages and enhancing CD8+ T cell–mediated antitumor immunity. Mechanistically, K63-linked ubiquitination at the K167 site of phosphorylated STAT2 (p-STAT2) facilitates its binding to LC3B, promoting the loading of p-STAT1 and p-STAT2 into extracellular vesicles and intercellular transference from tumor cells to macrophages, which, however, is suppressed by USP5-mediated STAT2 deubiquitination. Genetic depletion or pharmacological inhibition of USP5 promotes autophagy-dependent unconventional protein secretion of p-STAT1 and p-STAT2, leading to the induction of CXCL9+ macrophages. This process promotes the expression of T cell chemokines and upregulates the antigen presentation machinery, thereby enhancing radiation-induced CD8+ T cell antitumor immunity and radiotherapy efficacy. Our findings reveal a critical role of USP5 in type I IFN–induced antitumor immunity, providing potential targets for improving the efficacy of radiotherapy.
Authors
Jun-Yan Li, Ying-Qing Li, Jia-Hao Dai, Sha Gong, Qing-Mei He, Jie-Wen Bai, Sai-Wei Huang, Ying-Qi Lu, Yu-Fei Duan, Sen-Yu Feng, Xi-Rong Tan, Xiao-Yu Liang, Jun Ma, Rui Guo, Na Liu
Abstract
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.
Authors
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
Abstract
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.
Authors
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
Abstract
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.
Authors
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
Abstract
Secondary bacterial infection, often caused by Streptococcus pneumoniae (Spn), is one of the most frequent and severe complications of influenza A virus (IAV)-induced pneumonia. Phenotyping of the pulmonary immune cell landscape after IAV infection revealed a substantial depletion of the tissue-resident alveolar macrophage (TR-AM) population at day 7, which was associated with increased susceptibility to Spn outgrowth. To elucidate the molecular mechanisms underlying TR-AM depletion, and to define putative targets for treatment, we combined single-cell transcriptomics and cell-specific PCR profiling in an unbiased manner, using in vivo models of IAV infection and IAV/Spn co-infection. The TNF superfamily 14 (TNFSF14) ligand-receptor axis was revealed as the driving force behind post-influenza TR-AM death during the early infection phase, enabling the transition to pneumococcal pneumonia, while intrapulmonary transfer of genetically modified TR-AMs and antibody-mediated neutralization of specific pathway components alleviated disease severity. With a mainly neutrophilic expression and a high abundance in the bronchoalveolar fluid (BALF) of patients with severe virus-induced ARDS, TNFSF14 emerged as a key determinant of virus-driven lung injury. Targeting the TNFSF14-mediated intercellular communication network in the virus-infected lung can, therefore, improve host defense, minimizing the risk of subsequent bacterial pneumonia, and ameliorating disease outcome.
Authors
Christina Malainou, Christin Peteranderl, Maximiliano Ruben Ferrero, Ana Ivonne Vazquez-Armendariz, Ioannis Alexopoulos, Katharina Franz, Klara Knippenberg, Julian Better, Mohammad Estiri, Cheng-Yu Wu, Hendrik Schultheis, Judith Bushe, Maria-Luisa del Rio, Jose Ignacio Rodriguez-Barbosa, Klaus Pfeffer, Stefan Günther, Mario Looso, Achim Dieter Gruber, István Vadász, Ulrich Matt, Susanne Herold
Abstract
Resistance to genotoxic therapies remains a major contributor to tumor recurrence and treatment failure, yet the mechanisms by which cancer cells escape these therapies through DNA damage response (DDR) activation are not fully understood. Here, we identify a DDR regulatory pathway in which glycogen synthase kinase 3 β (GSK3B), a multifunctional serine/threonine kinase, governs DNA double-strand break (DSB) repair pathway choice by phosphorylating 53BP1 at threonine 334 (T334) — a site distinct from canonical ATM targets. This phosphorylation event disrupts 53BP1’s interaction with nonhomologous end joining (NHEJ) effectors PTIP and RIF1, promoting their dissociation from DSBs and inhibiting 53BP1-driven NHEJ. Simultaneously, T334 phosphorylation facilitates the recruitment of CtIP and RPA32 for DNA end resection and promotes homologous recombination (HR) by enabling BRCA1 and RAD51 loading. Notably, the phospho-deficient T334A mutant of 53BP1, unlike 53BP1 loss, accumulates aberrantly at DSBs along with PTIP/RIF1, impairs end resection, and suppresses HR activity. Importantly, both genetic and pharmacologic disruption of the GSK3B–53BP1 axis sensitizes tumors to PARP inhibitors (PARPi) independently of BRCA1 status. Together, these findings reveal a GSK3B-dependent mechanism that regulates DSB repair pathway choice and provide a rationale for targeting this axis to enhance PARPi efficacy in solid tumors regardless of BRCA1 status.
Authors
Heba S. Allam, Scarlett Acklin-Wehnert, Ratan Sadhukhan, Mousumi Patra, Fen Xia
Abstract
Demyelination associated microglia (DMAM) orchestrate the regenerative response to demyelination by clearing myelin debris and promoting oligodendrocyte maturation. Peroxisomal metabolism has emerged as a candidate regulator of DMAMs, though the cell-intrinsic contribution in microglia remains undefined. Here we elucidate the role of peroxisome integrity in DMAMs using cuprizone mediated demyelination coupled with conditional knockout of peroxisome biogenesis factor 5 (PEX5) in microglia. Absent demyelination, PEX5 conditional knockout (PEX5cKO) had minimal impact on homeostatic microglia. However, during cuprizone-induced demyelination, the emergence of DMAMs unmasked a critical requirement for peroxisome integrity. At peak demyelination, PEX5cKO DMAMs exhibited increased lipid droplet burden and reduced lipophagy suggestive of impaired lipid catabolism. Although lipid droplet burden declined during the remyelination phase, PEX5cKO DMAMs accumulated intralysosomal crystals and curvilinear profiles, which features were largely absent in controls. Aberrant lipid processing was accompanied by elevated lysosomal damage markers and downregulation of the lipid exporter gene Apoe, consistent with defective lipid clearance. Furthermore, the disruptions in PEX5cKO DMAMs were associated with defective myelin debris clearance and impaired remyelination. Together, these findings delineate a stage-specific role for peroxisomes in coordinating lipid processing pathways essential to DMAM function and necessary for enabling a pro-remyelinating environment.
Authors
Joseph A. Barnes-Vélez, Xiaohong Zhang, Yaren L. Peña Señeriz, Kiersten A. Scott, Yinglu Guan, Jian Hu
Abstract
Ciliary dysfunction results in multi-organ involved developmental diseases, collectively known as ciliopathies. The B9D1-B9D2-MKS1 protein complex maintains the gatekeeper function at the ciliary transition zone (TZ). However, the function of B9 proteins and the mechanisms underlying why different variants in the same B9 gene cause different ciliopathies are not fully understood. Here, we investigated the function of B9 proteins and revealed two critical functions. First, the B9 complex interacted with and anchored TMEM67 to the TZ membrane. Disruption of the B9-TMEM67 complex reduced posttranslational-modifications of axonemal microtubules due to deregulation of tubulin-modifying enzymes within cilia. Second, B9 proteins localized to centrioles prior to ciliogenesis, where they facilitated the initiation of ciliogenesis. Finally, we identified B9D2 variants in a cohort of patients with Joubert syndrome (JBTS). Consistent with the dual functions, we found that the JBTS-associated B9D2 variants primarily affected axonemal microtubule modifications without disrupting ciliogenesis, whereas the Meckel syndrome (MKS)-associated B9D2 variant disrupted both ciliogenesis and axonemal microtubule modifications. Thus, besides its role as a gatekeeper for ciliary membrane proteins, the B9 complex also controls axonemal microtubule post-translational modifications and early stages of ciliogenesis, providing insights into the distinct pathologies arising from different variants of the same gene.
Authors
Ruida He, Yan Li, Minjun Jin, Huike Jiao, Yue Shen, Qize Han, Xilang Pan, Suning Wang, Zaisheng Lin, Jingshi Li, Chao Lu, Dan Meng, Zongfu Cao, Qing Shang, Nan Lv, Kai Wan, Huafang Gao, Xu Ma, Haiyan Yin, Haishuang Chang, Liang Wang, Minna Luo, Junmin Pan, Chengtian Zhao, Muqing Cao
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ISSN: 0021-9738 (print), 1558-8238 (online)