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Light-induced retinal ganglion cell damage in vivo involves Dexras1.

Sang A, Cheng Y, Lu H, Chen D, Gao R, Shen A - Mol. Vis. (2011)

Bottom Line: Administration of NOS inhibitor decreased the expression of cleaved caspase-3 and Dexras1.Exposure to light caused the transient high expression of Dexras1, which was colabeled with apoptotic marker, nNOS, and the C-terminal PSD95/DLG/ZO-1 ligand of nNOS in RGCs.Administration of the NOS inhibitor prevented RGC apoptosis by decreasing cleaved caspase-3 and Dexras1 expression.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, the Affiliated Hospital of Nantong University, Medical College, Nantong University, Nantong, China. amsang@yahoo.cn

ABSTRACT

Purpose: Light-induced retinal degeneration is a vision-threatening retinal disease. Light can damage not only photoreceptor cells but also retinal ganglion cells (RGCs). This study was aimed to observe the spatiotemporal expression of dexamethasone-induced Ras protein 1 (Dexras1) and document the effect of Dexras1 on RGC damage after light exposure.

Methods: Adult Sprague-Dawley rats were exposed to bright white light for 2 h. Reverse transcriptase-PCR (RT-PCR) and western blot analysis were used to analyze mRNA and protein expression of Dexras1. The spatial distribution of Dexras1 and outer nuclear layer (ONL) thickness were evaluated by immunohistochemistry. Immunofluorescence was performed to observe the colocalization of Dexras1. In addition, cell apoptosis in this model was measured using terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL). Finally, the effect of systemic administration of nitric oxide synthase (NOS) inhibitor on the retina was investigated by western blot analysis and immunofluorescence.

Results: Dexras1 expression increased at 6 h and reached the peak at 1 day, gradually recovering to the baseline level at 7 days after light exposure. Dexras1 immunoreactivity was detected in RGCs and colabeled with cleaved caspase-3 after light exposure, whereas cleaved caspase-3 immunoreactivity was undetectable in the ONL. However, immunohistochemistry demonstrated that the ONL thickness decreased after light exposure and TUNEL revealed that photoreceptor cell apoptosis also occurred. In addition, the ternary complex of Dexras1, neuronal NOS (nNOS), and the C-terminal PSD95/DLG/ZO-1 ligand of nNOS was observed in RGCs. Administration of NOS inhibitor decreased the expression of cleaved caspase-3 and Dexras1.

Conclusions: Exposure to light caused the transient high expression of Dexras1, which was colabeled with apoptotic marker, nNOS, and the C-terminal PSD95/DLG/ZO-1 ligand of nNOS in RGCs. Administration of the NOS inhibitor prevented RGC apoptosis by decreasing cleaved caspase-3 and Dexras1 expression. Dexras1-mediated RGC damage appears to act through activation of nNOS in this model.

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Related in: MedlinePlus

Dexras1 protein level upregulated in the retina after light exposure. A: Total protein was extracted from normal and injured retinas at various times after light exposure, then assessed by western blot analysis. B: Relative protein level represented a ratio between the amount of target gene and amount of endogenous glyceraldehyde-3-phosphate dehydrogenase (GAPDH) control. Groups marked with an asterisk were significantly different from the normal group. The data are means±standard error of mean (SEM; n=5, *p<0.05).
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f2: Dexras1 protein level upregulated in the retina after light exposure. A: Total protein was extracted from normal and injured retinas at various times after light exposure, then assessed by western blot analysis. B: Relative protein level represented a ratio between the amount of target gene and amount of endogenous glyceraldehyde-3-phosphate dehydrogenase (GAPDH) control. Groups marked with an asterisk were significantly different from the normal group. The data are means±standard error of mean (SEM; n=5, *p<0.05).

Mentions: Semiquantitative RT–PCR was performed to investigate the temporal pattern of Dexras1 mRNA expression after light exposure. We found that mRNA for Dexras1 was relatively low in the normal retina, increased beginning at 6 h after light exposure (p<0.05) and reached the peak at 1 day, gradually recovering to the baseline level at 7 days (Figure 1A,B). In comparison with RT–PCR analysis, we performed western blot analysis to detect Dexras1 protein expression. The trends of Dexras1 protein expression were similar to that of Dexras1 mRNA expression. At 6 h after light exposure, Dexras1 protein expression increased, reached the peak at 1 day, and then gradually declined from 3 to 7 days (Figure 2A,B).


Light-induced retinal ganglion cell damage in vivo involves Dexras1.

Sang A, Cheng Y, Lu H, Chen D, Gao R, Shen A - Mol. Vis. (2011)

Dexras1 protein level upregulated in the retina after light exposure. A: Total protein was extracted from normal and injured retinas at various times after light exposure, then assessed by western blot analysis. B: Relative protein level represented a ratio between the amount of target gene and amount of endogenous glyceraldehyde-3-phosphate dehydrogenase (GAPDH) control. Groups marked with an asterisk were significantly different from the normal group. The data are means±standard error of mean (SEM; n=5, *p<0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3021566&req=5

f2: Dexras1 protein level upregulated in the retina after light exposure. A: Total protein was extracted from normal and injured retinas at various times after light exposure, then assessed by western blot analysis. B: Relative protein level represented a ratio between the amount of target gene and amount of endogenous glyceraldehyde-3-phosphate dehydrogenase (GAPDH) control. Groups marked with an asterisk were significantly different from the normal group. The data are means±standard error of mean (SEM; n=5, *p<0.05).
Mentions: Semiquantitative RT–PCR was performed to investigate the temporal pattern of Dexras1 mRNA expression after light exposure. We found that mRNA for Dexras1 was relatively low in the normal retina, increased beginning at 6 h after light exposure (p<0.05) and reached the peak at 1 day, gradually recovering to the baseline level at 7 days (Figure 1A,B). In comparison with RT–PCR analysis, we performed western blot analysis to detect Dexras1 protein expression. The trends of Dexras1 protein expression were similar to that of Dexras1 mRNA expression. At 6 h after light exposure, Dexras1 protein expression increased, reached the peak at 1 day, and then gradually declined from 3 to 7 days (Figure 2A,B).

Bottom Line: Administration of NOS inhibitor decreased the expression of cleaved caspase-3 and Dexras1.Exposure to light caused the transient high expression of Dexras1, which was colabeled with apoptotic marker, nNOS, and the C-terminal PSD95/DLG/ZO-1 ligand of nNOS in RGCs.Administration of the NOS inhibitor prevented RGC apoptosis by decreasing cleaved caspase-3 and Dexras1 expression.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, the Affiliated Hospital of Nantong University, Medical College, Nantong University, Nantong, China. amsang@yahoo.cn

ABSTRACT

Purpose: Light-induced retinal degeneration is a vision-threatening retinal disease. Light can damage not only photoreceptor cells but also retinal ganglion cells (RGCs). This study was aimed to observe the spatiotemporal expression of dexamethasone-induced Ras protein 1 (Dexras1) and document the effect of Dexras1 on RGC damage after light exposure.

Methods: Adult Sprague-Dawley rats were exposed to bright white light for 2 h. Reverse transcriptase-PCR (RT-PCR) and western blot analysis were used to analyze mRNA and protein expression of Dexras1. The spatial distribution of Dexras1 and outer nuclear layer (ONL) thickness were evaluated by immunohistochemistry. Immunofluorescence was performed to observe the colocalization of Dexras1. In addition, cell apoptosis in this model was measured using terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL). Finally, the effect of systemic administration of nitric oxide synthase (NOS) inhibitor on the retina was investigated by western blot analysis and immunofluorescence.

Results: Dexras1 expression increased at 6 h and reached the peak at 1 day, gradually recovering to the baseline level at 7 days after light exposure. Dexras1 immunoreactivity was detected in RGCs and colabeled with cleaved caspase-3 after light exposure, whereas cleaved caspase-3 immunoreactivity was undetectable in the ONL. However, immunohistochemistry demonstrated that the ONL thickness decreased after light exposure and TUNEL revealed that photoreceptor cell apoptosis also occurred. In addition, the ternary complex of Dexras1, neuronal NOS (nNOS), and the C-terminal PSD95/DLG/ZO-1 ligand of nNOS was observed in RGCs. Administration of NOS inhibitor decreased the expression of cleaved caspase-3 and Dexras1.

Conclusions: Exposure to light caused the transient high expression of Dexras1, which was colabeled with apoptotic marker, nNOS, and the C-terminal PSD95/DLG/ZO-1 ligand of nNOS in RGCs. Administration of the NOS inhibitor prevented RGC apoptosis by decreasing cleaved caspase-3 and Dexras1 expression. Dexras1-mediated RGC damage appears to act through activation of nNOS in this model.

Show MeSH
Related in: MedlinePlus