Regulatory Mechanisms of CHD7 and PAX4 Gene Mutations on Proliferation and Apoptosis in Chondrocytes

Mutations in Chromodomain Helicase DNA Binding Protein 7 (CHD7) and Paired Box Gene 4 (PAX4) are critical for normal cartilage development and are implicated through their impact on chondrocyte functions. This study examines how these genetic alterations specifically modulate Tumor protein p53 (p53) expression to affect cellular proliferation and apoptosis, shedding light on potential therapeutic targets for mitigating developmental anomalies in cartilage.

Using Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)- associated protein 9 (Cas9), specific mutations were introduced into CHD7 and PAX4 in chondrocytes. Subsequent analyses included 5-ethynyl-2'-deoxyuridine (EdU) assay for proliferation, Terminal deoxynucleotidyl Transferase dUTP Nick End Labeling (TUNEL) staining for apoptosis, quantitative real-time polymerase chain reaction (qRTPCR), and Western blot alongside co-immunoprecipitation (Co-IP) to evaluate expression levels and protein interactions.

Mutations in CHD7 and PAX4 resulted in decreased proliferation and increased apoptosis in chondrocytes. Notably, these mutations disrupted the interaction between the mutant proteins and p53, leading to altered expression of apoptotic regulators such as Bcl2-associated X protein (Bax), B-cell lymphoma 2 (Bcl2), indicating activation of p53-dependent apoptotic pathways.

This study elucidates the core molecular mechanism by which mutations in the CHD7 and PAX4 genes disrupt their interaction with p53, leading to aberrant activation of the p53-dependent apoptotic pathway. These findings provide a new theoretical basis and potential intervention strategies for developing p53 pathwaytargeted therapies to treat related cartilage developmental disorders. Future research should focus on in vivo validation and mechanistic refinement.

The study reveals that CHD7 and PAX4 mutations exacerbate the apoptotic pathways in chondrocytes by enhancing the activity of p53, leading to decreased cell proliferation and increased apoptosis. These findings underscore the mutations' profound impact on cartilage cell dynamics and highlight the therapeutic potential of targeting p53 to correct the cellular imbalances caused by these genetic changes in cartilage-related developmental disorders.