RNF4

RING finger protein 4 (RNF4) functions as a SUMO-targeted ubiquitin ligase, regulating protein stability and post-translational modification^[1]. Mechanistically, RNF4 recognizes phosphorylated transcription factors such as c-Myc, β-catenin, c-Jun, and N-ICD, stabilizing them via atypical polyubiquitin chains and chromatin docking^[2]. This stabilization enhances Wnt- and Notch-dependent gene expression, contributing to tumorigenesis and supporting cancer cell survival^[2][3]. RNF4 also modulates nuclear-cytoplasmic transport and SUMO-dependent degradation of PML-RARα in acute promyelocytic leukemia models, thereby influencing the therapeutic response to arsenic trioxide^[4][5]. In metabolic disease models, RNF4 promotes SUMOylation and ubiquitin-mediated degradation of hypoxia-inducible factor-2α (HIF-2α), enhancing PPARα signaling, reducing lipid accumulation, inflammation, and hepatocyte apoptosis, and mitigating nonalcoholic fatty liver disease progression^[1]. Compared with related isoforms, RNF4 exhibits distinct substrate specificity through its arginine-rich motif and RING domain, enabling selective stabilization of phosphorylated oncogenic targets rather than broad SUMOylated proteins^[2][4]. Experimental applications exploit RNF4 inhibitors or genetic knockdown to dissect its roles in cancer proliferation, DNA replication, and metabolic regulation^[3][1]. Collectively, RNF4 integrates post-translational modification, protein stabilization, and transcriptional regulation, making it a pivotal target for both oncological and metabolic research.