Caspase-9: involvement in secondary death of axotomized rat retinal ganglion cells in vivo.
Recently we have shown that adult rat retinal ganglion cells (RGCs) die by apoptosis following optic nerve (ON) transection, activating caspase-3. In the present study, we report that caspase-9, known to be an important activator of caspase-3, becomes activated in the axotomized adult rat retina as revealed by immunoblot analysis and protease activity assays. Reduction of caspase-9 activity by repeated intraocular injection of specific inhibitors significantly prevented RGC death. Caspase-9 activity was effectively blocked by inhibitor treatment and by application of IGF-I and BDNF, neurotrophic factors which have been shown to be highly neuroprotective in this model. Taken together, our data suggest that caspase-9 plays a critical role in apoptosis induction in axotomized RGCs in vivo and is regulated under treatment with growth and survival factors. Thus, providing more insight into the mechanisms underlying neuronal death and survival following trauma might serve as a basis to improve future therapeutic strategies preventing or at least reducing the severe consequences of neuronal injury.
Kermer
P
P
Department of Neurology, University of Tübingen, Hoppe-Seyler-Str. 3, 72076 Tübingen, Germany. pkermer@burnham-inst.org
Ankerhold
R
R
Klöcker
N
N
Krajewski
S
S
Reed
J C
JC
Bähr
M
M
D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D019771:Axotomy; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D018696:Neuroprotective Agents / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012165:Retinal Ganglion Cells / Q000166:cytology* / Q000201:enzymology*
D019208:Brain-Derived Neurotrophic Factor; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D018696:Neuroprotective Agents; D009842:Oligopeptides; C403754:benzyloxycarbonyl-leucyl-glutamyl-histidyl-aspartic acid fluoromethyl ketone; D007334:Insulin-Like Growth Factor I; C506435:Casp9 protein, rat; D053453:Caspase 9; D020169:Caspases