Abstract WP124: Targeting Prodeath Signaling Upstream Of Mitochondria Damage-cathepsins In Astrocytes Contributes To Neuroprotection Against Cerebral Ischmia
The roles of cathepsins in the ischemic astrocytic injury remain unclear. Here we test the hypothesis that the activation of cathepsin B and cathepsin L contribute to astrocytic injury via inhibiting cathepsins-mitochondrial apoptotic signaling patheways during acute focal ischemia and oxygen-glucose deprivation (OGD). In a rat model of pMCAO, CA-074Me, a selective inhibitor of cathepsin B, or Clik148, a selective inhibitor of cathepsin L, reduced the infarct volume, improved the neurological deficits and increased the expression of MAP2 and GFAP at 24 h after ischemia. In OGD-induced primary cultured astrocytes injury, CA-074Me or Clik148 significantly decreased the LDH leakage and increased the number of astrocytes in a dose-dependent fasion, and also increased the expression of GFAP. Immunofluorescence showed that the dots distribution of cathepsin L or cathepsin B was seen in astrocytes in the ischemic cortex of sham, while the diffussion distribution of cathepsin L or B was seen in astrocytes in the ischemic cortex of ischemic control rats at 3 h or 6 h after ischemia, suggesting the release of cathepsin L or cathepsin B from lysosome to cytosol after ischemia and the activation of cathepsin L or cathepsin B in ischemic astrocytes. pMCAO also induced the activation of caspase-3 in ischemic astrocytes at 12 h after iscemia. CA-074Me or Clik148 reversed pMCAO-induced activation of cathepsin B or cathepsin L and caspase-3 in ischemic astrocytes. Western Blot analysis showed that OGD induced an increase in activated cathepsin B or cathepsin L, tBid and Caspase-3, reduced Cyt-c in mitochondria and increased Cyt-c in cytoplasm in astrocytes. CA-074Me or Clik148 blocked OGD-induced an increase in activated cathepsin B or cathepsin L, tBid and caspase-3, and a reduction in mitochondria Cyt-c and an increase in cytoplasm Cyt-c. The current findings provide the first evidence that targeting prodeath signaling upstream of mitochondria damage-cathepsins in astrocytes contributes to neuroprotection against cerebral ischmia via blocking the activation of cathepsins-caspase apoptotic signaling pathway in astrocytes.
- © 2012 by American Heart Association, Inc.