LncRNA SNHG14/miR-497a-5p/BACE1 axis modulates obesity-induced adipocyte inflammation and endoplasmic reticulum stress

Obesity is a metabolic disease with excess weight. LncRNA SNHG14 is abnormally expressed in numerous diseases. This research aimed to enucleate the lncRNA SNHG14 role in obesity. Adipocytes were treated with free fatty acid (FFA) to establish an in vitro model for obesity. Mice were fed a high-fat diet to construct an in vivo model. Gene levels were determined using quantitative real-time PCR (RT-PCR). The protein level was checked by western blot. The lncRNA SNHG14 role in obesity was assessed using western blot and enzyme-linked immunosorbent assay. The mechanism was estimated by Starbase, dual-luciferase reporter gene assay, and RNA pull-down. LncRNA SNHG14 function in obesity was estimated using mouse xenograft models, RT-PCR, western blot, and enzyme-linked immunosorbent assay. LncRNA SNHG14 and BACE1 levels were increased, but the miR-497a-5p level was decreased in FFA-induced adipocytes. Interference with lncRNA SNHG14 reduced endoplasmic reticulum (ER) stress-related molecules GRP78 and CHOP expressions in FFA-induced adipocytes, and decreased IL-1β, IL-6, and TNF-α expressions, indicating that lncRNA SNHG14 knockdown mitigated FFA-induced ER stress and inflammation in adipocytes. Mechanistically, lncRNA SNHG14 combined with miR-497a-5p, and miR-497a-5p targeted BACE1. Meanwhile, lncRNA SNHG14 knockdown reduced levels of GRP78, CHOP, IL-1β, IL-6, and TNF-α, while cotransfection with anti-miR-497a-5p or pcDNA-BACE1 abolished these trends. Rescue assays illustrated that lncRNA SNHG14 knockdown relieved FFA-induced adipocyte ER stress and inflammation through miR-497a-5p/BACE1. Meanwhile, lncRNA SNHG14 knockdown restrained adipose inflammation and ER stress caused by obesity in vivo. LncRNA SNHG14 mediated obesity-induced adipose inflammation and ER stress through miR-497a-5p/BACE1.

Hesperidin alleviates insulin resistance by improving HG-induced oxidative stress and mitochondrial dysfunction by restoring miR-149

BACKGROUND

Hesperidin, a natural flavanone, has been proven to have multiple protective effects in diabetic rats, such as antioxidant, anti-inflammatory and anti-apoptotic effects. However, the molecular mechanisms underlying the effects of hesperidin are not well elucidated.

METHODS

LO2 cells were stimulated with high glucose (HG, 33 mM) for 24 h to establish a model of oxidative stress. Then, cell viability was determined using the MTT assay. The antioxidant activities, including the reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels, mitochondrial membrane potential (MMP) and adenosine-triphosphate (ATP) production, were measured with the corresponding kits. The levels of gene expression, protein expression and methylation were detected using qRT-PCR, western blotting and methylation-specific PCR (MSP) assays, respectively.

RESULTS

Compared to the NG treatment, hesperidin treatment increased the viability and improved the oxidative stress, mitochondrial dysfunction and insulin resistance of HG-treated LO2 cells, and these effects were correlated with heightened SOD and GPx activities, increased MMP level and ATP generation, reduced MDA, ROS and glucose levels, and activated GSK3β/AKT and inactivated IRS1 signals. Mechanistically, hesperidin treatment enhanced the miR-149 expression level by reducing its promoter methylation by inhibiting DNMT1. Importantly, knockdown of miR-149 obviously abolished the biological roles of hesperidin.

CONCLUSIONS

Our findings demonstrated that hesperidin treatment ameliorated HG-induced insulin resistance by reducing oxidative stress and mitochondrial dysfunction partly by suppressing DNMT1-mediated miR-149 silencing.