Inhibition of miR-543 alleviates cardiac fibroblast-to-myofibroblast transformation and collagen expression in insulin resistance via targeting PTEN.

BACKGROUND: Myocardial interstitial fibrosis is an important manifestation of diabetic heart disease, and insulin resistance is one of the mechanisms of myocardial interstitial fibrosis. Some studies have found that miR-543 is associated with insulin resistance, but whether it plays a role in diabetic myocardial interstitial fibrosis remains unclear. This study aimed to investigate the role of miR-543 in diabetic myocardial interstitial fibrosis. METHODS: The combination of high glucose and high insulin was used to establish an insulin-resistant myocardial fibroblast model. The expression levels of miR-543, α-SMA, collagen Ⅰ, collagen Ⅲ and PTEN were detected. Cell proliferation and migration were detected. Luciferase reporter gene assay was used to verify the targeting relationship between miR-543 and PTEN. RESULTS: The expression of miR-543 was up-regulated in myocardial fibroblasts with insulin resistance, which was consistent with the results of bioinformatics analysis. The proliferation and migration levels of myocardial fibroblasts in insulin-resistant states were increased, and the expression levels of α-SMA, collagen Ⅰ and collagen Ⅲ were also increased. Inhibition of miR-543 expression could reverse the above changes. Target gene prediction and dual luciferase reporter assay demonstrated that miR-543 could bind to the 3'UTR region of PTEN. Moreover, the effect of miR-543 on insulin-resistant myocardial fibroblasts is mediated by targeting PTEN. CONCLUSIONS: Inhibition of miR-543 can reduce myocardial fibroblast-myofibroblast transformation and collagen expression in insulin-resistant states by targeting PTEN.

Pim1 knockout alleviates sarcopenia in aging mice via reducing adipogenic differentiation of PDGFRα+ mesenchymal progenitors.

BACKGROUND: Sarcopenia widely exists in elderly people and triggers numerous age-related events. The essential pathologic change lies in the increased intramuscular adipose tissue after aging with no exception to non-obese objects. Pim1 appears to be associated with adipogenic differentiation in recent studies, inspiring us to explore whether it regulates adipogenesis in aging muscles and affects sarcopenia. METHODS: Wild-type and Pim1 knockout C57/BL6J mice were randomized into young and old groups. Histo-pathological and molecular biological methods were applied to assess the intramuscular adipose tissue content, the atrophy and regeneration, and the expressions of Pim1 and adipogenic transcription factors. PDGFRα+ mesenchymal progenitors were separated and their replicative aging model were established. Different time of adipogenic induction and different amounts of Pim1 inhibitor were applied, after which the adipogenic potency were evaluated. The expressions of Pim1 and adipogenic transcription factors were measured through western blotting. RESULTS: The aging mice demonstrated decreased forelimb grip strength (P = 0.0003), hanging impulse (P < 0.0001), exhaustive running time (P < 0.0001), tetanic force (P = 0.0298), lean mass (P = 0.0008), and percentage of gastrocnemius weight in body weight (P < 0.0001), which were improved by Pim1 knockout (P = 0.0015, P = 0.0222, P < 0.0001, P = 0.0444, P = 0.0004, and P = 0.0003, respectively). To elucidate the mechanisms, analyses showed that Pim1 knockout decreased the fat mass (P = 0.0005) and reduced the intramuscular adipose tissue content (P = 0.0008) by inhibiting the C/EBPδ pathway (P = 0.0067) in aging mice, resulting in increased cross-sectional area of all and fast muscle fibres (P = 0.0017 and 0.0024 respectively), decreased levels of MuRF 1 and atrogin 1 (P = 0.0001 and 0.0329 respectively), and decreased content of Pax7 at the basal state (P = 0.0055). In vitro, senescent PDGFRα+ mesenchymal progenitors showed significantly increased the intracellular adipose tissue content (OD510) compared with young cells after 6 days of adipogenic induction (P < 0.0001). The Pim1 expression was elevated during adipogenic differentiation, and Pim1 inhibition significantly reduced the OD510 in senescent cells (P = 0.0040) by inhibiting the C/EBPδ pathway (P = 0.0047). CONCLUSIONS: Pim1 knockout exerted protective effects in sarcopenia by inhibiting the adipogenic differentiation of PDGFRα+ mesenchymal progenitors induced by C/EBPδ activation and thus reducing the intramuscular adipose tissue content in aging mice. These results provide a potential target for the treatment of sarcopenia.

CIDEC silencing attenuates diabetic nephropathy via inhibiting apoptosis and promoting autophagy.

OBJECTIVE: The role of cell death-inducing DFF45-like effector C (CIDEC) in insulin resistance has been established, and it is considered to be an important trigger factor for the progression of diabetic nephropathy (DN). We intend to explore whether CIDEC plays an important role in the regulation of DN and its potential mechanism. METHODS: High-fat diet and low dose streptozotocin were used to establish type 2 diabetic rat model. We investigate the role of CIDEC in the pathogenesis and process of DN through histopathological analysis, western blot and gene silencing. Meanwhile, the effect of CIDEC on renal tubular epithelial cells stimulated by high glucose was also verified. RESULTS: DM group exhibited glucose and lipid metabolic disturbance, with hypertrophy of kidneys, damaged renal function, increased apoptosis, decreased autophagy, glomerulosclerosis and interstitial fibrosis. CIDEC gene silencing improved metabolic disorder and insulin resistance, alleviated renal hypertrophy and renal function damage, decreased glomerular and tubular apoptosis, increased autophagy and inhibited renal fibrosis. At the cellular level, high glucose stimulation increased CIDEC expression in renal tubular epithelial cells, accompanied by increased apoptosis and decreased autophagy. CIDEC gene silencing can improve autophagy and reduce apoptosis. At the molecular level, CIDEC gene silencing also decreased the expression of early growth response factor (EGR)1 and increased the expression of adipose triglyceride lipase (ATGL). CONCLUSION: CIDEC gene silencing may delay the progression of DN by restoring autophagy activity and inhibiting apoptosis with the participation of EGR1and ATGL.

Hepcidin gene silencing ameliorated inflammation and insulin resistance in adipose tissue of db/db mice via inhibiting METs formation.

As a major feature of diabetes, inflammation is closely related to macrophage extracellular traps and the expression of hepcidin upregulated by diabetes is reportedly involved in chronic inflammation. Therefore, we aimed to explore whether hepcidin could be implicated in inflammation and macrophage extracellular traps (METs) formation. The diabetic db/db mouse model was established exhibiting insulin resistance (IR), inflammation, macrophages infiltration and higher expression of hepcidin, where samples were obtained from epididymal adipose tissue. We observed that inflammation and IR improved in adipose tissue of mice treated with hepcidin gene silencing. Furthermore, METs formation could be markedly inhibited via hepcidin gene silencing followed by attenuated inflammatory response due to METs, indicating hepcidin gene silencing played a key role in anti-inflammation by inhibiting METs formation. So, we concluded that hepcidin gene silencing has a potential for treatment of diabetes due to its ability to ameliorate inflammation via inhibiting METs formation.