Targeting long non-coding RNA MALAT1 alleviates retinal neurodegeneration in diabetic mice.

Aim: To observe the effect of inhibiting long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) on diabetic neurodegeneration.

Methods: Thirty-six 8-week-old C57BL/6 mice were randomly divided into normal control, diabetic control, diabetic scrambled small interfering RNAs (siRNAs) and diabetic MALAT1-siRNA groups. After diabetic induction with streptozocin intraperitoneally-injection, the diabetic MALAT1-siRNA group was intravitreally injected with 1 µL 20 µmol/L MALAT1 siRNA, and the diabetic scrambled siRNA group was injected with the same amount of scrambled siRNA. Electroretinography was performed to examine photoreceptor functions 16wk after diabetes induction. MALAT1 expression was detected real time polymerase chain reaction. Cone morphological changes were examined using immunofluorescence. Rod morphological changes were examined by determining outer nuclear layer (ONL) thickness.

Results: The upregulation of retinal MALAT1 expression was detected in the diabetic control mice, while MALAT1 expression in the diabetic MALAT1-siRNA mice was decreased by 91.48% compared to diabetic control mice. The diabetic MALAT1-siRNA and diabetic control mice showed lower a-wave and b-wave amplitudes than did the normal control mice in scotopic and photopic electroretinogram, while the diabetic MALAT1-siRNA mice showed higher amplitudes than diabetic control mice. Morphological examination revealed that ONL thickness in the diabetic MALAT1-siRNA and diabetic control mice was lower than normal control mice. However, ONL thickness was greater in the diabetic MALAT1-siRNA mice than diabetic control mice. Moreover, the diabetic control mice performed a sparser cone cell arrangement and shorter outer segment morphology than diabetic MALAT1-siRNA mice.

Conclusion: Inhibiting retinal MALAT1 results in mitigative effects on the retinal photoreceptors, thus alleviating diabetic neurodegeneration.