Anti-apoptotic effects of human granulocyte colony-stimulating factor (G-CSF) on retinal ganglion cells after optic nerve crush are PI3K/AKT-dependent.
The purpose of present study is to dissect the role of PI3K/AKT signaling in the anti-apoptotic effects of human granulocyte colony-stimulating factor (G-CSF) on rat retinal ganglion cells (RGCs) after optic nerve (ON) crush. The ONs of seventy-two adult male Wistar rats were crushed by a standardized method. Control eyes received a sham operation. G-CSF or phosphate-buffered saline (PBS) was immediately administrated after the ON event for 5 days. Twelve rats were used to investigate the signaling pathways using western blot analysis. In other sixty rats, each eye also received intravitreal injections of PI3K/AKT inhibitor (LY294002) or PBS immediately after the experiments. Rats were euthanized at 1 or 2 weeks after the experiment. RGC density was counted by retrograde labeling with Fluorogold. Western blot analysis of p-AKT, TUNEL assays, and immunohistochemistry of the retinas were conducted. Two weeks after ON injury, RGC densities in the central and mid-peripheral retinas of ON-crushed, G-CSF treated rats were significantly higher than those of corresponding ON-crushed, G-CSF-treated and LY294002-injected rats (survival rates of 60% vs. 39% and 43% vs. 33%, respectively; p < 0.01). Decreased TUNEL staining and the up-regulations of p-AKT signaling in retinas of ON-crushed, G-CSF-treated rats were blocked by intravitreal injections of LY294002. The double staining showed that p-AKT expression co-localized with RGCs in the ON crushed, G-CSF treated retinas. In conclusion, the anti-apoptotic effects of G-CSF on RGCs are PI3K/AKT signaling dependent in the retinas to rescue RGCs after ON crush injury.
Tsai
Rong Kung
RK
Department of Ophthalmology, Buddhist Tzu Chi General Hospital, Hualien, Taiwan. rktsai@tzuchi.com.tw
Chang
Chung Hsing
CH
Sheu
Min-Muh
MM
Huang
Zei-Lun
ZL
D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000494:pharmacology*; D015153:Blotting, Western; D002452:Cell Count; D002470:Cell Survival; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019084:Fluorescent Antibody Technique, Indirect; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D007124:Immunoenzyme Techniques; D020287:In Situ Nick-End Labeling; D008297:Male; D009025:Morpholines / Q000494:pharmacology; D009409:Nerve Crush; D018696:Neuroprotective Agents / Q000494:pharmacology*; D051058:Oncogene Protein v-akt / Q000378:metabolism*; D020221:Optic Nerve Injuries / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051381:Rats; D017208:Rats, Wistar; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology
D051017:Apoptosis Regulatory Proteins; D002867:Chromones; D004791:Enzyme Inhibitors; D016179:Granulocyte Colony-Stimulating Factor; D009025:Morpholines; D018696:Neuroprotective Agents; D051058:Oncogene Protein v-akt; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one