Down-regulation of apoptosis mediators by RNAi inhibits axotomy-induced retinal ganglion cell death in vivo.
Transection of the optic nerve induces an apoptotic degeneration of retinal ganglion cells (RGC) in the rat retina. The immediate early gene c-Jun, the proapoptotic Bcl-2 family member Bax and the apoptosome constituent Apaf-1 have been shown previously to play major roles in the induction or execution of the apoptosis cascade. In this study we have designed and generated short interfering RNAs (siRNAs) against c-Jun, Bax and Apaf-1, which were injected into the optic nerve stump in order to inhibit axotomy-induced apoptosis. siRNAs were first tested in vitro to ensure silencing efficiency. In vivo, a clear neuronal localization of Cy3-labelled siRNA could be visualized in retinal flat mounts. Retinas that were injected with anti-Apaf-1- and anti-c-Jun-siRNA showed significantly more surviving RGC than non-injected or anti-EGFP-injected controls (approximately 2- to 3-fold, respectively). Anti-Bax-siRNA-injected retinas showed a trend towards an increased RGC number (not significant). Regulation of target proteins in situ could be visualized by immunohistochemical stainings. We conclude that (i) c-Jun and Apaf-1 play major roles in the apoptotic cascade of RGC and may represent useful targets for antiapoptotic strategies in RGC in vivo, and (ii) injection of siRNAs into the optic nerve stump is a new method to down-regulate target genes specifically in RGC.
Lingor
Paul
P
Department of Neurology, University of Göttingen, Faculty of Medicine, S2-Laboratory, Waldweg 33, 37073 Göttingen, Germany. plingor@gwdg.de
Koeberle
Paulo
P
Kügler
Sebastian
S
Bähr
Mathias
M
D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D053477:Apoptotic Protease-Activating Factor 1; D019771:Axotomy; D002460:Cell Line; D002470:Cell Survival / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics*; D005260:Female; D020868:Gene Silencing; D016758:Genes, jun; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D016372:RNA, Antisense / Q000235:genetics* / Q000493:pharmacokinetics; D034741:RNA, Small Interfering; D051381:Rats; D017207:Rats, Sprague-Dawley; D012165:Retinal Ganglion Cells / Q000378:metabolism / Q000473:pathology*; D014162:Transfection; D051028:bcl-2-Associated X Protein
C506594:Apaf1 protein, rat; D053477:Apoptotic Protease-Activating Factor 1; C494828:Bax protein, rat; D011506:Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016372:RNA, Antisense; D034741:RNA, Small Interfering; D051028:bcl-2-Associated X Protein