The MDM2 gene, also known as murine double minute 2 homolog, is a key regulator in cellular processes, primarily known for its role in the p53 tumor suppressor pathway. Located on human chromosome 12, the MDM2 gene encodes an E3 ubiquitin ligase that targets the p53 protein for proteasomal degradation, thereby controlling p53 activity in cellular stress responses. This negative feedback loop ensures that p53-mediated functions, such as DNA repair, cell cycle arrest, and apoptosis, are tightly regulated to prevent uncontrolled cell proliferation. Dysregulation of MDM2, often due0 to gene amplification or overexpression, is closely associated with the development and progression of various cancers because it leads to the suppression of p53 tumor suppressor function. Therefore, MDM2 has become a promising therapeutic target, and inhibitors aimed at disrupting the MDM2-p53 interaction and restoring p53 activity in cancer cells are currently under development.
MDM2 adenovirus refers to genetically engineered adenoviral vectors used to modulate MDM2 expression or function for research or therapeutic purposes. Adenoviruses are commonly used in gene therapy due to their high transduction efficiency, broad host range, and ability to carry large gene fragments. MDM2 adenoviruses are crucial for studying the role of MDM2 in tumorigenesis, cell cycle regulation, and therapeutic resistance. Furthermore, MDM2 adenoviruses have been used in cancer gene therapy strategies aimed at reactivating p53 by inhibiting MDM2 or directly targeting tumors with MDM2 overexpression. Despite challenges such as immunogenicity and transient expression, adenovirus-based approaches remain a versatile platform for advancing MDM2-related biomedical research.
Vascular calcification (VC) is often associated with cardiovascular and metabolic diseases. However, the molecular mechanisms linking VC to these diseases remain unclear. Here, researchers report that MDM2-induced ubiquitination of histone deacetylase 1 (HDAC1) mediates VC. Loss of HDAC1 activity by chemical inhibitors or genetic ablation enhances VC. HDAC1 protein, but not mRNA, is reduced in cellular and animal calcification models and in human calcified coronary arteries. Under calcification-inducing conditions, proteasomal degradation of HDAC1 precedes VC, mediated by the MDM2 E3 ubiquitin ligase that initiates HDAC1 K74 ubiquitination. MDM2 overexpression enhances VC, whereas MDM2 depletion attenuates VC. A decoy peptide spanning HDAC1 K74 and the MDM2 inhibitor RG 7112 inhibit VC in vitro and in vivo. These results reveal a previously unappreciated ubiquitination pathway and suggest that MDM2-mediated HDAC1 ubiquitination is a novel therapeutic target for VC.
The researchers investigated whether MDM2 could induce VC. MDM2 adenovirus (Ad-MDM2) infection induced calcium deposition in RVSMCs only at higher doses (the fourth column in Figure 1a). However, under Pi treatment, Ad-MDM2 significantly enhanced calcium deposition in RVSMCs in a dose-dependent manner (the fifth to eighth columns in Figure 1a). In addition, MDM2 siRNA significantly attenuated Pi-induced calcium deposition in A10 cells (Figure 1b).
Figure 1. (a) Adenoviral infection of MDM2 enhanced Pi-induced VC in a dose-dependent manner. (b) MDM2 siRNA blunted Pi-induced VC in A10 cells. (Kwon D H, et al., 2016)
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The viral titer was high, and transduction efficiency in our cell lines was impressive. Highly recommended for anyone exploring p53 pathways!
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