SARS-CoV-2 continues to evolve with enhanced transmissibility, a feature primarily mediated by its spike (S) protein. While expression of the S protein in human cells can induce the accumulation of reactive oxygen species (ROS), the regulatory mechanisms governing this process remain poorly understood. Here, we identify the human protein HCLS1-associated protein X-1 (HAX1) as a key regulator that mitigates SARS-CoV-2S-induced ROS accumulation. A genome-wide screen revealed HAX1 as a binding partner of the SARS-CoV-2S protein in mammalian cells. HAX1 specifically interacts with the S1 subunit of S, and its deficiency effectively abolishes S-induced activation of endoplasmic reticulum (ER) stress responses, including the unfolded protein response (UPR). Notably, HAX1-dependent UPR activation is unique to SARS-CoV-2S and certain variants and is not triggered by other UPR inducers. Loss of HAX1 markedly exacerbates SARS-CoV-2S-induced ROS accumulation and mitochondrial dysfunction. Collectively, our findings uncover a previously unrecognized mechanism by which S modulates host stress responses and establish HAX1 as a host factor involved in SARS-CoV-2-related processes. © 2025 Federation of European Biochemical Societies.

Ubiquitination/ubiquitylation, one of the most fundamental post-translational modifications, regulates almost every critical cellular process in eukaryotes. Emerging evidence has shown that essential components of numerous biological processes undergo ubiquitination in mammalian cells upon exposure to diverse stresses, from exogenous factors to cellular reactions, causing a dazzling variety of functional consequences. Various forms of ubiquitin signals generated by ubiquitylation events in specific milieus, known as ubiquitin codes, constitute an intrinsic part of myriad cellular stress responses. These ubiquitination events, leading to proteolytic turnover of the substrates or just switch in functionality, initiate, regulate, or supervise multiple cellular stress-associated responses, supporting adaptation, homeostasis recovery, and survival of the stressed cells. In this review, we attempted to summarize the crucial roles of ubiquitination in response to different environmental and intracellular stresses, while discussing how stresses modulate the ubiquitin system. This review also updates the most recent advances in understanding ubiquitination machinery as well as different stress responses and discusses some important questions that may warrant future investigation. ©The Author(s) 2023. Published by Oxford University Press on behalf of Higher Education Press.

Strategies to degrade steroid receptors and their alternative splicing isoforms are critical for disease management. Here we report that celastrol recruited the ubiquitin ligase UBE3A and degraded androgen receptor (AR), AR-v7, and glucocorticoid receptor (GR) to suppress prostate cancer development. UBE3A was not an optimal endogenous AR ubiquitin ligase in mice and patients, but celastrol promoted the interaction between UBE3A and AR. Multiple domains of AR, including the DNA binding domain (DBD), were implicated into the UBE3A-AR interaction. Sharing a conserved DBD, GR, AR-v7, and other steroid receptors were recognized and degraded by UBE3A after celastrol treatment. Thus, celastrol suppressed prostate cancer cell proliferation more potently than enzalutamide. Modifying the carboxyl group of celastrol improved its anti-tumor activity. Together, our findings revealed that celastrol might be a potential molecular glue to enhance the interaction between UBE3A and steroid receptors to degrade multiple steroid receptors and splicing isoforms in prostate cancer, paving a way for further drug optimization and disease treatment.

我们发现E3泛素连接酶GXB1可以与视黄酸降解代谢酶CYP26A1相互作用，并且泛素化修饰它，在不影响蛋白水平的情况下抑制了它的活性。随后我们构建了GXB1基因敲除的小鼠模型，发现GXB1缺失的小鼠表现出自闭症样的行为，可能是由于视黄酸降解加快导致的。而向其回补视黄酸后，可以缓解自闭症样的行为，进一步说明GXB1基因敲除可能是视黄酸代谢异常导致的。此外，我们通过对GXB1敲除小鼠进行RNA-seq分析，发现GXB1缺失后会引起神经细胞形态、突触的功能等生命活动异常，提示GXB1敲除之后，减少了对CYP26A1的泛素化修饰，使其活性增加，加速视黄酸的降解，视黄酸水平降低影响了正常的神经电活动，最终导致自闭症的发生。这些成果有助于更加深入的理解自闭症发病机制，并且提供了“补充视黄酸“”这个治疗自闭症的新思路。另外，我们还明确了m6A与果蝇早期胚胎的母源mRNA的降解的相关性，发现FMR1优先结合m6A修饰的RNA,通过相分离影响FMR1的RNA颗粒大小和活性，调节早期胚胎母源mRNA的降解。这有助于我们深入理解果蝇早期胚胎发育过程。We have basically accomplished these goals,and published 6 scientific papers(2 of them acknowledged this project at the first place).We found out that E3 ubiquitin ligase GXB1 interacts with and ubiquities CYP26A1,the metabolic enzyme of retinoic acid,results in a decrease in its metabolic activity without changing the protein levels.Next,we discovered that the autistic-like behaviors in GXB1 knockout mice might result from increasing degradation of retinoic acid(RA),which could be rescued by supplement of RA.The results of RNA-seq also revealed that neural network and synaptic functions were affected by GXB knockout.These findings suggested that knockout of GXB1 decreased the ubiquitination of CYP26A1,increased its metabolic activity and accelerated the degradation of RA.The normal neural activity was impaired,therefore induced autistic-like behaviors in mice.Our results should help people understand the pathogenesis of autism and provide a new strategy to treat autism,supplementation of retinoic acid._x000D_Furthermore,we revealed the association between m6A modification and mRNA degradation during early embryonic development.We found that FMR1 protein bound m6A modified mRNA in prior and could influence the FMR1-RNA particle by phase-phase separation,then regulate the degradation of mRNA in early embryos.These findings should help us to better understand the early embryonic development of fruit fly.