Downregulation of miR-320 Alleviates Endoplasmic Reticulum Stress and Inflammatory Response in 3T3-L1 Adipocytes.

Abstract

MicroRNAs serve important roles in the regulation of endoplasmic reticulum stress (ERs). This study aimed to investigate the role of microRNA-320 (miR-320) in the development of ERs and the inflammatory response in 3T3-L1 adipocytes. The adipose tissue expression levels of miR-320 and ERs markers (GRP78, GRP94, Derlin-1 and CHOP) and the serum concentration of inflammatory cytokines (TNF-α, NF-κB and IL-6) in obese patients were evaluated using quantitative real-time RT-PCR or enzyme-linked immunosorbent assay. The correlation of miR-320 with genes involved in ERs and inflammation was analyzed. The effects of miR-320 on ERs and inflammation were explored using mature 3T3-L1 adipocytes, which were pretreated with palmitic acid (PA). ERs markers and inflammatory cytokines were all upregulated in obese patients. Adipose tissue miR-320 expression was also increased in obese patients, and had positive correlations with the levels of ERs markers and inflammatory cytokines. After PA treatment, the levels of ERs markers and inflammatory cytokines were elevated significantly in 3T3-L1 adipocytes. Moreover, miR-320 expression was increased in the cells under ERs status. The upregulation of miR-320 could enhance the expression of ERs markers and inflammatory cytokines, but the downregulation of miR-320 resulted in the opposite results. The data of this study indicate that miR-320 expression is upregulated in ERs status, and the downregulation of miR-320 ameliorates ERs and the inflammatory response in 3T3-L1 adipocytes. We consider that the approaches to decrease miR-320 expression may be novel therapeutic strategies for the treatment of obesity and obesity-related diseases.