Abstract 3866: The Inhibition of WWP-1 and Activation of AMPKa2 Are Important Mediators of Ischemic Stroke
Background: Tuberous sclerosis complex (TSC) and Mammalian target of rapamycin (mTOR) mediate various functions such as cell survival, obesity, and cellular responses in injury. However, the signaling mechanism linking focal cerebral ischemia is unknown. Because inhibition of the mTOR signaling pathway contributes to the pathogenesis of ischemic stroke, we hypothesize that inhibition of WW domain protein 1 (WWP-1) and activation of AMPKα2 mediate neuroprotection effect via WWP-1/AMPKα2/TSC/mTOR/S6 signaling pathways.
Methods: To investigate whether the inhibition of WWP-1 and activation of AMPKα2 could exert neuroprotective effect via mTOR signaling pathways, we performed transient focal cerebral ischemia. Wild-type and TSC2+− mice (20-22g) were administered either vehicle or rapamycin (5 mg/kg, i.p., 1d and 5d), before MCAO. After 2 hrs of MCAO followed by 22 hrs of reperfusion, Infarct size was determined with TTC staining and protein levels were assessed in ischemic core and contralateral (non-ischemic core) hemisphere region.
Results: Compare to vehicle mice, mTOR/S6 level was decreased in ischemic brain region during ischemia (0.5, 1, 2h MCAO). After reperfusion (after 2h MCAO), phospho-S6 in mice brain was quickly over-expressed. Acute administration of rapamycin had no effect on cerebral infarct size in WT mice but chronic administration of rapamycin exhibited significantly increased infarct size and higher NDS following MCAO. Compare to vehicle mice, TSC2+− mice showed increased mTOR/S6 level in brain and reduced cerebral infarct size (64.2 ± 5.96; n=7 vs 92.6 ± 6.08, n=7, p<0.01).
Conclusions: These findings indicate that the inhibition of WWP-1 and activation of AMPKα2 reduced infarct size via TSC2/mTOR/S6 signal transduction in focal cerebral ischemia. These results suggest that inhibition of WWP-1 and activation of AMPKα2 may have therapeutic benefits in ischemic stroke.
- © 2012 by American Heart Association, Inc.