Neural Regeneration Research ›› 2024, Vol. 19 ›› Issue (12): 2698-2707.doi: 10.4103/NRR.NRR-D-23-01064

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MicroRNA-502-3p regulates GABAergic synapse function in hippocampal neurons

Bhupender Sharma1, Melissa M. Torres1, Sheryl Rodriguez1, Laxman Gangwani2, Subodh Kumar1, 3, *   

  1. 1Center of Emphasis in Neuroscience, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX, USA; 2Bond Life Sciences Center and Department of Veterinary Pathobiology, University of Missouri, Columbia, MO, USA; 3L. Frederick Francis Graduate School of Biomedical Sciences, Texas Tech University Health Sciences Center, El Paso, TX, USA
  • Online:2024-12-15 Published:2024-03-30
  • Contact: Subodh Kumar, PhD, subodh.kumar@ttuhsc.edu.
  • Supported by:
    This study was supported by the National Institute on Aging (NIA), National Institutes of Health (NIH), Nos. K99AG065645, R00AG065645, and R00AG065645-04S1 (to SK), and NIH research grants, NINDS, No. R01 NS115834 and NINDS/NIA, No. R01 NS115834-02S1 (to LG).

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Abstract: Gamma-aminobutyric acid (GABA)ergic neurons, the most abundant inhibitory neurons in the human brain, have been found to be reduced in many neurological disorders, including Alzheimer’s disease and Alzheimer’s disease-related dementia. Our previous study identified the upregulation of microRNA-502-3p (miR-502-3p) and downregulation of GABA type A receptor subunit α-1 in Alzheimer’s disease synapses. This study investigated a new molecular relationship between miR-502-3p and GABAergic synapse function. In vitro studies were performed using the mouse hippocampal neuronal cell line HT22 and miR-502-3p agomiRs and antagomiRs. In silico analysis identified multiple binding sites of miR-502-3p at GABA type A receptor subunit α-1 mRNA. Luciferase assay confirmed that miR-502-3p targets the GABA type A receptor subunit α-1 gene and suppresses the luciferase activity. Furthermore, quantitative reverse transcription-polymerase chain reaction, miRNA in situ hybridization, immunoblotting, and immunostaining analysis confirmed that overexpression of miR-502-3p reduced the GABA type A receptor subunit α-1 level, while suppression of miR-502-3p increased the level of GABA type A receptor subunit α-1 protein. Notably, as a result of the overexpression of miR-502-3p, cell viability was found to be reduced, and the population of necrotic cells was found to be increased. The whole cell patch-clamp analysis of human-GABA receptor A-α1/β3/γ2L human embryonic kidney (HEK) recombinant cell line also showed that overexpression of miR-502-3p reduced the GABA current and overall GABA function, suggesting a negative correlation between miR-502-3p levels and GABAergic synapse function. Additionally, the levels of proteins associated with Alzheimer’s disease were high with miR-502-3p overexpression and reduced with miR-502-3p suppression. The present study provides insight into the molecular mechanism of regulation of GABAergic synapses by miR-502-3p. We propose that micro-RNA, in particular miR-502-3p, could be a potential therapeutic target to modulate GABAergic synapse function in neurological disorders, including Alzheimer’s disease and Alzheimer’s disease-related dementia.

Key words: Alzheimer’s disease, GABAergic synapse, gamma-aminobutyric acid type A receptor subunit α-1 (GABRα1), microRNA-502-3p (miR-502-3p), miRNA in situ hybridization, Patch-clamp