The role of alphaA- and alphaB-crystallins in the survival of retinal ganglion cells after optic nerve axotomy.
OBJECTIVE
Stress-induced crystallin expression is commonly viewed as activation of the cell survival mechanism. The authors analyzed the expression of alphaA- and alphaB-crystallins in a rat optic nerve transection (ONT) model characterized by specific retinal ganglion cell (RGC) degeneration and determined their role in RGC survival.


METHODS
ONT was performed on adult Wistar rats. Quantitative and spatial expression were examined with Western blot analysis and immunohistochemistry, respectively. Electroporation was used to deliver alphaA and alphaB expression constructs to RGCs. Cell-protective effects of alphaA and alphaB overexpression after ONT were determined by RGC density analysis.


RESULTS
Expression of alphaA and alphaB in the retina was observed predominantly in the ganglion cell layer, where most crystallin-positive cells were colocalized with RGCs. Levels of alphaA and alphaB proteins after ONT were decreased 1.6-fold. The effect of alphaA and alphaB overexpression on RGC survival was evaluated 7 and 14 days after axotomy. At day 7 after ONT, 1426 +/- 70 and 1418 +/- 81 RGCs/mm(2) were present in retinas electroporated with alphaA and alphaB expression constructs, respectively, compared with 1010 +/- 121 RGCs/mm(2) in sham-transfected or 1016 +/- 88 RGCs/mm(2) in nontransfected retinas. Numbers of surviving RGCs at 14 days were 389 +/- 57 and 353.57 +/- 60 cells/mm(2) after alphaA and alphaB transfection, respectively, compared with 198 +/- 29 cells/mm(2) after transfection with the vector alone or 206 +/- 60 cells/mm(2) in nontransfected retinas.


CONCLUSIONS
Increases of approximately 95% and 75% in RGC survival mediated by alphaA and alphaB overexpression, respectively, were observed 14 days after ONT. At day 7, the RGC protective effect of alphaA and alphaB overexpression was approximately 40%.
Munemasa
Yasunari
Y
Jules Stein Eye Institute, University of California at Los Angeles School of Medicine, Los Angeles, CA 90095, USA.
Kwong
Jacky M K
JM
Caprioli
Joseph
J
Piri
Natik
N
D000818:Animals; D019771:Axotomy; D015153:Blotting, Western; D002452:Cell Count; D002470:Cell Survival / Q000502:physiology; D019610:Cytoprotection / Q000502:physiology; D018274:Electroporation; D019084:Fluorescent Antibody Technique, Indirect; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D009900:Optic Nerve / Q000502:physiology* / Q000601:surgery; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012162:Retinal Degeneration / Q000378:metabolism* / Q000473:pathology; D012165:Retinal Ganglion Cells / Q000378:metabolism* / Q000473:pathology; D015854:Up-Regulation; D038202:alpha-Crystallin A Chain / Q000502:physiology*; D038203:alpha-Crystallin B Chain / Q000502:physiology*
D012333:RNA, Messenger; D038202:alpha-Crystallin A Chain; D038203:alpha-Crystallin B Chain; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins