miR-335-3p improves type II diabetes mellitus by IGF-1 regulating macrophage polarization.

Previous studies have found that miR-335 is highly expressed in type II diabetes mellitus (T2DM) models and is related to insulin secretion, but there are few studies on the regulatory effects of miR-335-3p on insulin resistance and macrophage polarization in T2DM patients. This study aims to explore the effects of miR-335-3p on insulin resistance and macrophage polarization in T2DM patients. Blood glucose (insulin tolerance tests, glucose tolerance tests) and body weight of the T2DM model were measured; macrophages from adipose tissue were isolated and cultured, and the number of macrophages was detected by F4/80 immunofluorescence assay; the Real-time quantitative polymerase chain reaction (qPCR) assay and Western blot assay were used to detect the miR-335-3p expression levels, insulin-like growth factor 1 (IGF-1), M1-polarizing genes (inducible nitric oxide synthase [iNOS] and TNF-α) as well as M2-polarizing genes (IL-10 and ARG-1). The targeting link between miR-335-3p and IGF-1 was confirmed using bioinformatics and dual luciferase assay. The results showed that miR-335-3p expression level in adipose tissue of the T2DM model was significantly decreased, and the mice's body weight and blood glucose levels dropped considerably, miR-335-3p inhibited the number of macrophages, inhibiting the iNOS and TNF-α relative mRNA expression levels, and up-regulated the IL-10 and ARG-1 relative mRNA expression levels, miR-335-3p negatively regulated target gene IGF-1, IGF-1 significantly increased the iNOS and TNF-α mRNA and protein expression levels, decreasing the IL-10 and ARG-1 mRNA and protein expression levels, indicating that miR-335-3p could affect the T2DM process by regulating macrophage polarization via IGF-1.

STUB1 increases adiponectin expression by inducing ubiquitination and degradation of NR2F2, thereby reducing hepatic stellate cell activation and alleviating non-alcoholic fatty liver disease.

BACKGROUND: Adiponectin (APN) has exhibited ameliorating effects on non-alcoholic fatty liver disease (NAFLD). This study investigates the roles of APN and its regulatory molecules in hepatic stellate cell (HSC) activation and the progression of NAFLD. METHODS: Mice were subjected to a high-fat diet (HFD) to establish NAFLD models. Liver tissue was examined for lipid metabolism, fibrosis, and inflammation. Mouse 3T3-L1 adipocytes were exposed to palmitic acid (PA) to mimic a high-fat environment. The conditioned medium (CM) from adipocytes was collected for the culture of isolated mouse HSCs. Gain- or loss-of-function studies of APN, nuclear receptor subfamily 2 group F member 2 (NR2F2), and STIP1 homology and U-box containing protein 1 (STUB1) were performed to analyze their roles in NAFLD and HSC activation in vivo and in vitro. RESULTS: APN expression was poorly expressed in HFD-fed mice and PA-treated 3T3-L1 adipocytes, which was attributed to the transcription inhibition mediated by NR2F2. Silencing of NR2F2 restored the APN expression, ameliorating liver steatosis, fibrosis, and inflammatory cytokine infiltration in mouse livers and reducing HSC activation. Similarly, the NR2F2 silencing condition reduced HSC activation in vitro. However, these effects were counteracted by artificial APN silencing. STUB1 facilitated the ubiquitination and protein degradation of NR2F2, and its upregulation mitigated NAFLD-like symptoms in mice and HSC activation, effects reversed by the NR2F2 overexpression. CONCLUSION: This study highlights the role of STUB1 in reducing HSC activation and alleviating NAFLD by attenuating NR2F2-mediated transcriptional repression of APN.