Although
hyperhomocysteinemia (HHcy) elicits lower than normal body weights and skeletal muscle weakness, the mechanisms remain unclear. Despite the fact that HHcy-mediated enhancement in ROS and consequent damage to regulators of different cellular processes is relatively well established in other organs, the nature of such events is unknown in skeletal muscles. Previously, we reported that HHcy attenuation of PGC-1α and HIF-1α levels enhanced the likelihood of
muscle atrophy and declined function after
ischemia. In the current study, we examined muscle levels of
homocysteine (Hcy) metabolizing
enzymes,
anti-oxidant capacity and focused on
protein modifications that might compromise PGC-1α function during ischemic angiogenesis. Although skeletal muscles express the key
enzyme (MTHFR) that participates in re-methylation of Hcy into
methionine, lack of trans-sulfuration
enzymes (CBS and CSE) make skeletal muscles more susceptible to the HHcy-induced
myopathy. Our study indicates that elevated Hcy levels in the CBS-/+ mouse skeletal muscles caused diminished
anti-oxidant capacity and contributed to enhanced total
protein as well as PGC-1α specific nitrotyrosylation after
ischemia. Furthermore, in the presence of NO donor SNP, either
homocysteine (Hcy) or its cyclized version,
Hcy thiolactone, not only increased PGC-1α specific
protein nitrotyrosylation but also reduced its association with PPARγ in C2C12 cells. Altogether these results suggest that HHcy exerts its myopathic effects via reduction of the PGC-1/PPARγ axis after
ischemia.