Gelsolin, a
calcium-regulated actin severing and capping
protein, is highly expressed in murine and human hearts after
myocardial infarction and is associated with progression of
heart failure in humans. The biological role of
gelsolin in cardiac remodeling and
heart failure progression after injury is not defined. To elucidate the contribution of
gelsolin in these processes, we randomly allocated
gelsolin knockout mice (GSN(-/-)) and wild-type littermates (GSN(+/+)) to left anterior descending coronary artery
ligation or
sham surgery. We found that GSN(-/-) mice have a surprisingly lower mortality, markedly reduced
hypertrophy, smaller late
infarct size, less interstitial
fibrosis, and improved cardiac function when compared with GSN(+/+) mice. Gene expression and
protein analysis identified significantly lower levels of
deoxyribonuclease (
DNase) I and reduced nuclear translocation and biological activity of
DNase I in GSN(-/-) mice. Absence of
gelsolin markedly reduced
DNase I-induced apoptosis. The association of
hypoxia-inducible factor (HIF)-1alpha with
gelsolin and actin filaments cleaved by
gelsolin may contribute to the higher activation of
DNase. The expression pattern of HIF-1alpha was similar to that of
gelsolin, and HIF-1alpha was detected in the
gelsolin complex by coprecipitation and HIF-1alpha bound to the promoter of
DNase I in both gel-shift and promoter activity assays. Furthermore, the phosphorylation of Akt at Ser473 and expression of Bcl-2 were significantly increased in GSN(-/-) mice, suggesting that
gelsolin downregulates prosurvival factors. Our investigation concludes that
gelsolin is an important contributor to
heart failure progression through novel mechanisms of HIF-1alpha and
DNase I activation and downregulation of antiapoptotic survival factors.
Gelsolin inhibition may form a novel target for
heart failure therapy.