Aim/Introduction Obesity is considered an important risk factor for many metabolic disorders, especially type 2 diabetes mellitus, and microRNAs (miRNAs) play a vital role in the development of type 2 diabetes mellitus. Therefore, we conducted this study to investigate the role of miR‐4431 in the obesity‐associated pathobiology of type 2 diabetes mellitus. Materials and methods Subjects were divided into normal control (n = 36), obese (n = 36), and type 2 diabetes mellitus (n = 12) groups, and serum miR‐4431 levels were analyzed. Adenovirus‐vectored miR‐4431 mimic or sponge was intraperitoneally injected into the normal diet group and the high‐fat diet group (HFD) mice to investigate glucose tolerance, insulin sensitivity, and lipid levels. The downstream target genes of miR‐4431 were predicted using bioinformatics, and they were verified in vitro. Results Serum miR‐4431 levels were significantly high in obese and type 2 diabetes mellitus individuals, and positively correlated with the body mass index and fasting plasma glucose levels. In HFD mice, miR‐4431 levels in the serum, white adipose tissue, and liver were significantly increased. Moreover, miR‐4431 impaired glucose tolerance, insulin sensitivity, and lipid metabolism in mice. Bioinformatic prediction suggested that TRIP10 and PRKD1 could be the downstream target genes of miR‐4431. The HFD mice showed a remarkable reduction in the mRNA levels of TRIP10 and PRKD1 in the liver, which were countered by blocking miR‐4431. In HepG2 and L02 cells, miR‐4431 could downregulate TRIP10 and PRKD1 while blocking glucose uptake. The luciferase reporter assay showed that miR‐4431 could bind TRIP10 and PRKD1 3′‐UTR. Conclusion miR‐4431 targets TRIP10/PRKD1 and impairs glucose metabolism.

Background In previous study, we found that the content of medium-chain fatty acid Caprylic Acid (FFA C8:0) may be an important risk factor of obesity induced prostate cancer (PCa). However, the relationship between FFA C8:0 and PCa has not been reported. In this study, we explored whether the FFA C8:0 can promotes the progression of PCa by up-regulating Krüppel-like factor 7 (KLF7). Methods We collected tissues from PCa patients and Benign Prostate Hyperplasia (BPH), constructed a primary-tumor bearing mouse model with obesity through high-fat diet, and observed the tumor formation ability of PCa cells. In vitro, CCK8 assay, plate cloning, Transwell and scratch experiment were used to detect the changes in biological behavior of PCa cells stimulated by FFA C8:0. Results First, we found that the expression level of KLF7 is higher in PCa tissues of patients, and the expression of KLF7 is positively correlated with tumour-promoting gene IL-6, while it is negative correlated with another tumour-suppressor gene p21. Then, this study found that PCa cells were more likely to form tumors in diet induced obese mice. Compared with the normal diet group (ND), the expression levels of KLF7 in tumor tissues in high-fat diet group (HFD) were higher. Futhermore, we verified that high concentrations of FFA C8:0 can promote the biological behavior of PCa cells by activating KLF7/IL-6/p21 signaling pathway, which is mediated by the GPR84. Conclusions Our research may provide a potential target for clinical prevention and treatment of PCa which induced by obesity.

The present study aimed to explore the molecular mechanism underlying the regulation of glucose metabolism by miR-548ag. For the first time, we found that miR-548ag expression was elevated in the abdominal adipose tissue and serum of subjects with obesity and type 2 diabetes mellitus (T2DM). The conditional knockout of adipose tissue Dicer notably reduced the expression and content of miR-548ag in mouse adipose tissue, serum, and liver tissue. The combined use of RNAseq, an miRNA target gene prediction software, and the dual luciferase reporter assay confirmed that miR-548ag exerts a targeted regulatory effect on DNMT3B and DPP4. miR-548ag and DPP4 expression was increased in the adipose tissue, serum, and liver tissue of diet-induced obese mice, while DNMT3B expression was decreased. It was subsequently confirmed both in vitro and in vivo that adipose tissue-derived miR-548ag impaired glucose tolerance and insulin sensitivity by inhibiting DNMT3B and upregulating DPP4. Moreover, miR-548ag inhibitors significantly improved the adverse metabolic phenotype in both obese mice and db/db mice. These results revealed that the expression of the adipose tissue-derived miR-548ag increased in obese subjects, and that this could upregulate the expression of DPP4 by targeting DNMT3B, ultimately leading to glucose metabolism disorder. Therefore, miR-548ag could be utilized as a potential target in the treatment of T2DM.

Obesity is a high‐risk factor in the development of endometrial cancer (EC). Our previous study observed that miR‐548ag was significantly overexpressed in the sera of obese individuals. Here, we report the function of miR‐548ag and its mechanism in promoting the obesity‐related progression of EC. The content of miR‐548ag was increased in the serum of obese EC individuals. Bioinformatics analysis indicated that the survival rate of EC patients with a higher expression of miR‐548ag was significantly reduced. The Mps One Binder Kinase Activator 1B (MOB1B, the core member of the Hippo signaling pathway) is a direct target gene of miR‐548ag, which is inversely correlated with the expression of miR‐548ag. The overexpression of miR‐548ag enhances the proliferation, invasion, and migration, and inhibits apoptosis by downregulating the expression of MOB1B, leading to the deactivation of the Hippo pathway in EC cell lines and contributing to tumor progression in vivo. Our study has established that miR‐548ag functions as an oncogene by suppressing MOB1B in the development of obesity‐related EC.

In the obesity context, inflammatory cytokines secreted by adipocytes lead to insulin resistance and are key to metabolic syndrome development. In our previous study, we found that the transcription factor KLF7 promoted the expression of p‐p65 and IL‐6 in adipocytes. However, the specific molecular mechanism remained unclear. In the present study, we found that the expression of KLF7, PKCζ, p‐IκB, p‐p65, and IL‐6 in epididymal white adipose tissue (Epi WAT) in mice fed a high‐fat diet (HFD) was significantly increased. In contrast, the expression of PKCζ, p‐IκB, p‐p65, and IL‐6 was significantly decreased in Epi WAT of KLF7 fat conditional knockout mice. In 3T3‐L1 adipocytes, KLF7 promoted the expression of IL‐6 via the PKCζ/NF‐κB pathway. In addition, we performed luciferase reporter and chromatin immunoprecipitation assays, which confirmed that KLF7 upregulated the expression of PKCζ transcripts in HEK‐293T cells. Collectively, our results show that KLF7 promotes the expression of IL‐6 by upregulating PKCζ expression and activating the NF‐κB signaling pathway in adipocytes.