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.

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.

Background: Our previous study found that the increase of palmitic acid (PA) in serum after obesity is closely related to the development of endometrial cancer (EC), and the high concentration of PA can promote the biological behavior of EC cells by up-regulating the expression of KLF7, but the specific molecular mechanism are unclear. Methods: EC cells Ishikawa were treated with high concentrations(20μM and 50μM) of PA, the effects on the proliferative ability of Ishikawa cells were examined by CCK-8 and colony formation assay, and on the invasive and migratory ability of Ishikawa cells by transwell and scratch assay. RNA-Seq combined with double luciferase reporter gene experiment were used to confirm the key downstream target gene for KLF7. Constructing the model of obese mice with EC tumor, and collecting the endometrial tissues of EC patients and non-cancer individuals,we validated a possible molecular mechanism by which PA upregulation of KLF7 promotes EC development in vivo. The mRNA and protein expression levels of GPR40/120, KLF7 and HEY1 were detected in EC cells and tumor tissues by qRT-PCR and western-blot. Results: High concentrations of PA can up-regulate the expression of KLF7 through GPR40/120 and promote the biological behavior of EC cells. HEY1 may be a key downstream gene for KLF7 to promote the progression of EC. Under the state of obesity, the tumorigenesis ability of EC cells in mice was enhanced, and the expression of GPR40/120, KLF7 and HEY1 in tumor tissue increased. Up/down regulation of KLF7 can significantly enhance/weaken the tumorigenic ability of EC cells and promote/inhibit the expression of HEY1 in tumor tissues. The expression level of KLF7 and HEY1 in tumor tissues of EC individuals were significantly higher than that of non-cancer individuals. Conclusions: Increased PA content after obesity promotes the development of EC by activating the GPRs/KLF7/HEY1 signaling axis.

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