Articles written in Journal of Biosciences
Volume 43 Issue 5 December 2018 pp 985-1000 Article
Retinal injury plays a leading role in the onset of visual impairment. Current forms of treatment are not able to amelioratescarring, cell death and tissue and axon regeneration. Recently, microRNA-216a (miR-216a) has been reported to regulatesnx5, a novel notch signalling pathway component during retinal development. This study aims to elucidate the role ofmiR-216a in yttrium aluminium garnet (YAG) laser-induced retinal injury by targeting glial cell line-derived neurotrophicfactor (GDNF) via GDNF/GDNF family neurotrophic factor receptor α1 (GFRα1)/rearranged during transfection (RET)signalling pathway. Wistar male rats were first randomly assigned into control and model groups. Immunohistochemistrywas performed to detect the GDNF positive expression rate and terminal deoxynucleotidyl transferase-mediated dUTP nickend labelling (TUNEL) staining for apoptotic index (AI) of retinal tissue. Retinal neurons were divided into normal, blank,negative control (NC), miR-216a mimic, miR-216a inhibitor, siRNA-GDNF and miR-216a inhibitor+siRNA-GDNFgroups. Dual luciferase reporter assay was conducted in order to identify the targeting relationship between GDNF andmiR-216a. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot were used for theanalysis of mRNA and protein levels of miR-216a and related genes. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay was used to determine cell proliferation and flow cytometry was used to observe cell cycle andapoptosis. Results show that the model group had an increased GDNF positive rate, AI of retinal tissue and mRNA andprotein levels of cellular oncogene fos (c-fos), vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor(BDNF), GDNF, GFRα1 and bcl-2-associated X protein (bax), declined miR-216a level and mRNA and protein levels ofRET and bcl-2 compared with the control group. GDNF was verified as the target gene for miR-216a. Compared with theblank and NC groups, the miR-216a mimic and siRNA-GDNF groups had higher mRNA and protein levels of c-fos, VEGFand bax, cell number in the G1 phase and increased cell apoptosis but reduced BDNF, GDNF, GFRa1, RET and bcl-2expression, cell proliferation and cell numbers in the S phase, while the opposite trend was observed in the miR-216ainhibitor group. Taken together, our findings demonstrate that elevated GDNF levels can reduce the retinal injury, wherebydown-regulated miR-216a aggravates the YAG laser-induced retinal injury by targeting the GDNF level through the GDNF/GFRα1/RET signalling pathway.
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