Stroke, characterized by a disruption of blood supply to the brain, is a major cause of morbidity and mortality worldwide. Although
humanin, a 24-amino
acid polypeptide, has been identified to have multiple neuroprotective functions, the level of
humanin in plasma has been demonstrated to decrease with age, which likely limits the effects against
stroke injury. A potent
humanin analogue,
S14G-humanin (HNG), generated by replacement of Ser14 with
glycine, has been demonstrated to have 1,000-fold stronger biological activity than
humanin. The present study established an in vitro
oxygen glucose deprivation/reoxygenation (OGD/R) model using SH-SY5Y
neuroblastoma cells to mimic the in vivo
ischemia/reperfusion injury in
stroke. Adding HNG (0-10 µg/l) to SH-SY5Y cells to different extents blocked OGD/R-induced reduction of cell viability and antioxidative capacity, as well as decreased the elevated apoptosis rate induced by OGD/R, with the most evident effects at 1 µg/l HNG.
Janus kinase 2 (Jak2)/
signal transducer and activator of transcription 3 (Stat3) signaling was attenuated in OGD/R processes, yet reactivated with HNG treatment.
FLLL32 (5 µM), a specific inhibitor of the signal, abolished effects of HNG on anti-apoptosis and antioxidation in OGD/R processes. Co-treatment with HNG and
FLLL32 failed to interrupt upregulation of
cytochrome c,
B-cell lymphoma 2-associated X
protein and cleaved
caspase-3 provoked by OGD/R. Similar to
FLLL32, Jak2/Stat3 signaling activated by HNG was also repressed by inhibitor of
phosphoinositide 3-kinase (PI3K; 10 µM
LY294002) or
protein kinase B (AKT; 5 µM
MK-2206 2HCl). These data collectively indicated that HNG has
neuroprotective effects against OGD/R by reactivating Jak2/Stat3 signaling through the PI3K/AKT pathway, suggesting that HNG may be a promising agent in the management of
stroke.