Hsp20 is chaperone
protein that is highly and constitutively expressed in the brain, cardiac tissue and many other organs. Recently, it is well established that Hsp20 can enhance cardiac function and render cardioprotection. However, the potential benefits of Hsp20 and its phosphorylation form action on
ischemic stroke and its underlying mechanism(s) are largely unknown.To investigate whether Hsp20 exerts protective effects in vitro
ischemia/reperfusion (I/R) injury, mouse
neuroblastoma cells were subjected to
oxygen-
glucose deprivation (OGD) and reoxygenation. Expression
mRNA and
protein levels of Hsp20 were strongly downregulated in mouse N2A cells at the 0-hour and 6-hour recovery time points following 4 hours of OGD, and returned to basal level 12 and 24 hours after OGD treatment. The ratio of phosphorylated to total Hsp20
protein was not significantly affected by OGD treatment at the 0-hour and 6-hour recovery time points following 4 hours of OGD. However, markedly higher
serine phosphorylation of Hsp20 was observed 12 and 24 hours after OGD treatment. Furthermore, overexpression of Hsp20 reduced OGD-induced apoptosis by reducing the release of
cytochrome c from mitochondria to cytosol. However, blockade of Hsp20 phosphorylation at Ser16 abrogated this anti-apoptotic effect.Our data demonstrate that increased Hsp20 expression in mouse N2A
neuroblastoma cells protects against I/R injury, resulting in reduced apoptosis, which is by reducing the release of
cytochrome c from mitochondria to cytosol. Phosphorylation of Ser16 plays an important role in its protective effect. Thus, Hsp20 may constitute a new therapeutic target for cerebral ischemic diseases.