USP38 functions as an oncoprotein by downregulating the p53 pathway through deubiquitination and stabilization of MDM2
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Tripartite motif-containing protein 26 promotes colorectal cancer growth by inactivating p53
Tripartite motif-containing protein 26 (TRIM26) is an E3 ubiquitin ligase that exhibits divergent roles in various cancer types (oncogenic and anti-oncogenic). This study investigates the interaction of TRIM26 with the tumor suppressor protein p53 in colorectal cancer (CRC) cells by performing a comprehensive set of biochemical, cell-based assays, and xenograft experiments. As a result, we found that overexpression of TRIM26 significantly enhances CRC cell proliferation and colony formation, while knockdown of TRIM26 suppresses these processes. Xenograft experiments further validated the tumor-promoting role of TRIM26 in CRC. Supporting this is that TRIM26 is highly expressed in human CRC tissues as revealed by our analysis of the TCGA database. Biochemically, TRIM26 directly bound to the C-terminus of p53 and facilitated its ubiquitination, resulting in proteolytic degradation and attenuated p53 activity independently of MDM2. Also, TRIM26 increased the MDM2-mediated ubiquitination of p53 by binding to MDM2’s C-terminus. This study uncovers the oncogenic potential of TRIM26 in CRC by inhibiting p53 function. Through its ubiquitin ligase activity, TRIM26 destabilizes p53, consequently promoting CRC cell proliferation and tumor growth. These findings shed light on the complex involvement of TRIM26 in cancer and identify this ubiquitin ligase as a potential therapeutic target for future development of CRC treatment.
Targeting MDM2 affects spastin protein levels and functions: implications for HSP treatment
Spastin is a microtubule (MT) severing enzyme that regulates several cell functions associated with MT dynamics. A reduction in spastin protein levels is responsible for approximately 40% of cases of Hereditary Spastic Paraplegia (HSP), a neurodegenerative disease. Currently, there is no cure for HSP but strategies to induce a recovery of spastin levels are emerging as potential therapeutic approaches. Here, we show that MDM2 interacts with spastin MT-interacting and trafficking (MIT) domain. By biochemical and functional experiments, we demonstrate that MDM2 binds spastin and regulates its levels in a post-transcriptional manner independently of the E3 ubiquitin ligase activity. Of relevance, treatment of spastin-deficient cells with the MDM2 inhibitor Nutlin-3a can restore spastin levels and functions, such as cytokinetic abscission and sorting of transferrin receptor. These findings identify MDM2 as a novel interactor of spastin and a potential druggable regulator of its protein levels.
Lactylation-driven transcriptional activation of FBXO33 promotes gallbladder cancer metastasis by regulating p53 polyubiquitination
Gallbladder cancer (GBC) is the most common malignant tumor of the biliary tract and is often prone to early distant metastasis. However, the mechanisms underlying GBC’s invasive metastasis remain unclear. This study identified that F-box only protein 33 (FBXO33) expression is significantly elevated in GBC and is negatively associated with patient prognosis. In vivo and in vitro experiments demonstrated that knockdown of FBXO33 inhibits epithelial-mesenchymal transition (EMT) progression in GBC, while overexpression of FBXO33 promotes EMT progression. Mechanistically, FBXO33 regulates EMT progression by modulating the polyubiquitination of p53 at K291 and K292. Moreover, the upregulation of FBXO33 in GBC is driven by transcriptional regulation mediated by Yin Yang-1 (YY1). The lactylation modification of YY1 at K183 was found to be essential for the transcriptional activation of FBXO33. These findings underscore the role of the lactylation-driven FBXO33-p53 axis in promoting the invasive metastasis of GBC.
Iron homeostasis and ferroptosis in muscle diseases and disorders: mechanisms and therapeutic prospects
The muscular system plays a critical role in the human body by governing skeletal movement, cardiovascular function, and the activities of digestive organs. Additionally, muscle tissues serve an endocrine function by secreting myogenic cytokines, thereby regulating metabolism throughout the entire body. Maintaining muscle function requires iron homeostasis. Recent studies suggest that disruptions in iron metabolism and ferroptosis, a form of iron-dependent cell death, are essential contributors to the progression of a wide range of muscle diseases and disorders, including sarcopenia, cardiomyopathy, and amyotrophic lateral sclerosis. Thus, a comprehensive overview of the mechanisms regulating iron metabolism and ferroptosis in these conditions is crucial for identifying potential therapeutic targets and developing new strategies for disease treatment and/or prevention. This review aims to summarize recent advances in understanding the molecular mechanisms underlying ferroptosis in the context of muscle injury, as well as associated muscle diseases and disorders. Moreover, we discuss potential targets within the ferroptosis pathway and possible strategies for managing muscle disorders. Finally, we shed new light on current limitations and future prospects for therapeutic interventions targeting ferroptosis.
Insights on the crosstalk among different cell death mechanisms
The phenomenon of cell death has garnered significant scientific attention in recent years, emerging as a pivotal area of research. Recently, novel modalities of cellular death and the intricate interplay between them have been unveiled, offering insights into the pathogenesis of various diseases. This comprehensive review delves into the intricate molecular mechanisms, inducers, and inhibitors of the underlying prevalent forms of cell death, including apoptosis, autophagy, ferroptosis, necroptosis, mitophagy, and pyroptosis. Moreover, it elucidates the crosstalk and interconnection among the key pathways or molecular entities associated with these pathways, thereby paving the way for the identification of novel therapeutic targets, disease management strategies, and drug repurposing.
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