Unacylated ghrelin promotes skeletal muscle regeneration following hindlimb ischemia via SOD-2-mediated miR-221/222 expression.

Surgical treatment of peripheral artery disease,even if successful,does not prevent reoccurrence. under these conditions,increased oxidative stress is a crucial determinant of tissue damage. given its reported antioxidant effects,we investigated the potential of unacylated-ghrelin (unag) to reduce ischemia-induced tissue damage in a mouse model of peripheral artery disease. we show that unag but not acylated ghrelin (ag) induces skeletal muscle regeneration in response to ischemia via canonical p38/mitogen-actived protein kinase signaling unag protected against reactive oxygen species-induced cell injuries by inducing the expression of superoxide dismutase-2 (sod-2) in satellite cells. this led to a reduced number of infiltrating cd68(+) cells and was followed by induction of the myogenic process and a reduction in functional impairment. moreover,we found that mir-221/222,previously linked to muscle regeneration processes,was up-regulated and negatively correlated with p57(kip2) expression in unag-treated mice. unag,unlike ag,promoted cell-cycle entry in satellite cells of mice lacking the genes for ghrelin and its receptor (ghsr1a). unag-induced p38/mitogen-actived protein kinase phosphorylation,leading to activation of the myogenic process,was prevented in sod-2-depleted scs. by sirna technology,we also demonstrated that sod-2 is the antioxidant enzyme involved in the control of mir-221/222-driven posttranscriptional p57(kip2) regulation. loss-of-function experiments targeting mir-221/222 and local pre-mir-221/222 injection in vivo confirmed a role for mir-221/222 in driving skeletal muscle regeneration after ischemia. these results indicate that unag-induced skeletal muscle regeneration after ischemia depends on sod-2-induced mir-221/222 expression and highlight its clinical potential for the treatment of reactive oxygen species-mediated skeletal muscle damage.