J Neurosci. 2000 Sep 15;20(18):6879-87

Fas receptor and neuronal cell death after spinal cord ischemia

Matsushita K, Wu Y, Qiu J, Lang-Lazdunski L, Hirt L, Waeber C, Hyman BT, Yuan J, Moskowitz MA.

Abstract

Cell death from spinal cord injury is mediated in part by apoptotic mechanisms involving downstream caspases (e.g., caspase-3). Upstream mechanisms may involve other caspases such as procaspase-8, a 55 kDa apical caspase, which we found constitutively expressed within spinal cord neurons along with Fas. As early as 1.5 hr after transient ischemia, activated caspase-8 (p18) and caspase-8 mRNA appeared within neurons in intermediate gray matter and in medial ventral horn. We also detected evidence for an increase in death receptor complex by co-immunoprecipitation using Fas and anti-procaspase-8 after ischemia. At early time points, Fas and p18 were co-expressed within individual neurons, as were activated caspase-8 and caspase-3. Moreover, we detected p18 in cells before procaspase-3 cleavage product (p20), suggesting sequential activation. The appearance of cytosolic cytochrome c and gelsolin cleavage after ischemia was consistent with mitochondrial release and caspase-3 activation, respectively. Numerous terminal deoxynucleotidyl transferase-mediated DNA nick end-labeling-positive neurons contained p18 or p20 (65 and 80%, respectively), thereby supporting the idea that cells undergoing cell death contain both processed caspases. Our data are consistent with the idea that transient spinal cord ischemia induces the formation of a death-inducing signaling complex, which may participate in caspase-8 activation and sequential caspase-3 cleavage. Death receptors as well as downstream caspases may be useful therapeutic targets for limiting the death of cells in spinal cord.

PMID: 10995832