ObjectiveTo explore the protective effect and mechanism of Krüppel-like factor 7 (KLF7) overexpression on retinal ganglion cells (RGC) in mice after optic nerve crush (ONC). MethodsA total of sixty five 10-week-old C57BL/6J mice were randomly divided into five groups: blank control group (group A), intravitreal injection (IVT)-KLF7 group (group B), IVT-phosphate buffer saline-ONC group (group C), IVT-KLF7-ONC group (group D), and IVT-recombinant adeno-associated virus 2-enhanced green fluorescent protein-ONC group (group E), with 13 mice in each group. On the 7 days after the ONC model, the mice in each group were killed. RGC survival rate was counted by whole retina flat mount and immunofluorescence techniques. KLF7, nerve growth factor (NGF), tyrosine kinase A (TrkA), phosphorylated TrkA (pTrkA), tyrosine kinase B (TrkB) and phosphorylated TrkB (pTrk) were detected by western blot, growth associated protein 43 (GAP43), brain-derived neurotrophic factor, B lymphoblastoma-2 (Bcl-2), Bcl-2 associated X protein (BAX), Caspase-3 protein relative expression levels. One-way analysis of variance or Kruskal-Wallis test were used for comparison between groups. ResultsOn the 7 days after the ONC model, the density of RGC in the retina of groups A, B, C, D and E were (3 707.4±12.8), (3 582.4±13.3), (1 396.3±16.1), (1 658.3±22.2) and (1 323.6±16.9)/mm2, respectively. Compared with groups C and E, RGC density in group D was significantly increased, and the difference was statistically significant (P=0.028, 0.007). Compared with groups A, B, C and E, the relative expression levels of NGF, pTrkA, pTrkB, GAP43 and Bcl-2 proteins in the retina of mice in group D were increased, while the relative expression levels of BAX and Caspase-3 proteins were decreased, with statistical significance (P＜0.01). ConclusionIn mouse ONC model, overexpression of KLF7 can improve RGC survival rate, increase the relative expression levels of NGF, pTrkA, pTrkB, GAP43 and Bcl-2 proteins in retina, and decrease the relative expression levels of BAX and Caspase-3 proteins.
ObjectiveTo investigate the effect of heat shock protein B8 (HspB8) downregulation on retinal ganglion cell (RGC) and retinal function in the mice model of optic nerve injury (ONC).MethodsAdeno-Associated Virus (AAV) 2 AAV2-shHspB8-GFP was constructed to knockdown HspB8. 66 adult male C57/BL6 mice were randomly divided into the control group, the ONC group, the AAV2-shHspB8 group, the ONC+AAV2-shHspB8 group, and the ONC+AAV2- GFP group. There were 10, 20, 16, 10 and 10 mice respectively, and both eyes were used as experimental eyes. Western blot was used to evaluate the expression of HspB8 on day 3 and 7 after ONC. By GFP immunofluorescence staining, the efficacy of AAV2-shHspB8-GFP transfer was accessed. Moreover, it was possible to identify functional and RGC survival differences between groups by optomotor response (OMR), dark adapted full-field flash electroretinogram (ff-ERG), oscillatory potentials (OPs), photopic negative response (PhNR) and retinal flat-mount RGC counting 5 days after ONC. Comparisons between two groups were made using Mann-Whitney U test, unpaired t-test, unpaired t-test with Welch’s correction, one-way ANOVA, and Bonferroni t test.ResultsCompared with the control group, the expression of HSPB8 protein in the retina of mice in ONC3 group was significantly increased, and the difference was statistically significant (F=43.63, P＜0.01). Compared with the control group, the ONC group showed obviously lower visual acuity (P＜0.01), lower a-wave, b-wave, OPs, PhNR amplitude, longer b-wave latency (P＜0.05), and the survival rates of RGC in ONC3 group, ONC5 group and ONC7 group decreased in a time-dependent manner(F=384.90, P＜0.01). Transfection of AAV2 efficiency was highest on 4 weeks after IVT. Besides, there was no significant differences between the control group and the AAV2-shHspB8 group on visual acuity, ff-ERG, OPs, PhNR and RGC survival (P>0.05). In comparison of the control group, we found that RGC survival of the ONC5+AAV2-shHspB8 group was significantly elevated (F=10.62, P＜0.01).ConclusionsExpression of HspB8 on the retina can be induced by ONC. The investigation of RGC counting, visual acuity, and ff-ERG revealed that optic nerve injury destructed functionality of mice retina and resulted to RGC death ultimately. The Most crucial finding of this research is that HspB8 knockdown had a neuroprotective effect in RGC after ONC.