Lysine 222 in PPAR gamma 1 functions as the key site of MuRF2-mediated ubiquitination modification

Peroxisome proliferator-activated receptor gamma (PPAR gamma) plays key roles in the development, physiology, reproduction, and homeostasis of organisms. Its expression and activity are regulated by various posttranslational modifications. We previously reported that E3 ubiquitin ligase muscle ring finger protein 2 (MuRF2) inhibits cardiac PPAR gamma 1 protein level and activity, eventually protects heart from diabetic cardiomyopathy; furthermore, by GST-pulldown assay, we found that MuRF2 modifies PPAR gamma 1 via poly-ubiquitination and accelerates PPAR gamma 1 proteasomal degradation. However, the key ubiquitination site on PPAR gamma that MuRF2 targets for remains unclear. In the present study, we demonstrate that lysine site 222 is the receptor of MuRF2-mediated PPAR gamma 1 ubiquitination modification, using prediction of computational models, immunoprecipitation, ubiquitination assays, cycloheximide chasing assay and RT-qPCR. Our findings elucidated the underlying details of MuRF2 prevents heart from diabetic cardiomyopathy through the PPAR gamma 1 regulatory pathway.

Automated summary

Peroxisome proliferator-activated receptor gamma (PPAR gamma) is involved in important biological processes, and its regulation is influenced by various modifications. This study demonstrates that MuRF2 inhibits cardiac PPAR gamma 1 protein level and activity through poly-ubiquitination, ultimately protecting the heart from diabetic cardiomyopathy. Lysine site 222 on PPAR gamma 1 is identified as the target of MuRF2-mediated ubiquitination.