cpp32 messenger RNA neosynthesis is induced by fatal axotomy and is not regulated by athanatal Bcl-2 over-expression.
In vivo, neuronal over-expression of the anti-apoptotic protein Bcl-2 prevents axotomy-induced motoneuron death and prolongs life in a mouse model of familial amyotrophic lateral sclerosis. The mechanism of these protective effects is still unknown. We have examined, in situ, the influence of Bcl-2 over-expression on the messenger RNA level of two pro-apoptotic, bax and cpp32, and one anti-apoptotic, bcl-xl, regulators of neuronal death. In neonates wild-type mice, cpp32 mRNA was increased in axotomized, dying motoneurons. No changes in bax and bcl-xl messenger RNAs expression were detected. A similar course was observed in protected axotomized neonate motoneurons of transgenic mice over-expressing Bcl-2. In adult wild-type mice no motoneuron death was detected one week after axotomy: bax and cpp32 messenger RNAs were increased and bcl-xl messenger RNA was decreased. Four weeks after the lesion, 60% of the lesioned facial motoneurons had disappeared. In the remaining motoneurons only cpp32 messenger RNA expression was superior to control level. In Bcl-2 transgenic mice, no axotomy-induced facial motoneurons death was detected but the course of the neosynthesis of cell death genes messenger RNAs was similar to wild-type mice. Bax, Bcl-x and CPP32 immunoreactivity were increased in facial motoneurons after axotomy. Thus, fatal axotomy induces cell death genes bax and cpp32 messenger RNAs neosynthesis which is not prevented by athanatal Bcl-2 over-expression. This suggests that the protective effect of Bcl-2 results from interactions with Bax and CPP32 at the post-translation level without repercussion at the messenger RNA level. Axotomy induces cell death messenger RNA neosynthesis potentially harmful at long-term despite Bcl-2 over-expression.
Guarin
E
E
Geneva University, Science II, Department of Biochemistry, Switzerland.
Seuret
P
P
Nef
S
S
de Bilbao
F
F
Nef
P
P
Dubois-Dauphin
M
M
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis; D019771:Axotomy; D053148:Caspase 3; D020169:Caspases / Q000235:genetics*; D005154:Facial Nerve / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic; D019254:Genes, bcl-2; D006801:Humans; D017403:In Situ Hybridization; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009046:Motor Neurons / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein
C494826:BAX protein, human; C494811:BCL2L1 protein, human; C494827:Bax protein, mouse; C494812:Bcl2l1 protein, mouse; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D051028:bcl-2-Associated X Protein; D051020:bcl-X Protein; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases