Fas receptor and neuronal cell death after spinal cord ischemia.
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.
Matsushita
K
K
Neuroscience Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, USA.
Wu
Y
Y
Qiu
J
J
Lang-Lazdunski
L
L
Hirt
L
L
Waeber
C
C
Hyman
B T
BT
Yuan
J
J
Moskowitz
M A
MA
D000818:Animals; D017209:Apoptosis; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000235:genetics / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D004195:Disease Models, Animal; D004792:Enzyme Precursors / Q000235:genetics / Q000378:metabolism; D005260:Female; D018260:Gelsolin / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis; D015424:Reperfusion; D015398:Signal Transduction; D013116:Spinal Cord / Q000098:blood supply / Q000378:metabolism* / Q000473:pathology; D020760:Spinal Cord Ischemia / Q000378:metabolism* / Q000473:pathology; D019014:fas Receptor / Q000378:metabolism*
D003574:Cytochrome c Group; D004792:Enzyme Precursors; D018260:Gelsolin; D012333:RNA, Messenger; D019014:fas Receptor; C505409:Casp3 protein, mouse; C505526:Casp8 protein, mouse; C506434:Casp9 protein, mouse; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases