The mammalian ste20 kinase (MST) signaling pathway plays an important role in the regulation of apoptosis and cell cycle control. We sought to understand the role of MST2 kinase and Salvador homolog 1 (SAV1), a scaffolding protein that functions in the MST pathway, in adipocyte differentiation. MST2 and MST1 stimulated the binding of SAV1 to peroxisome proliferator-activated receptor γ (PPARγ), a transcription factor that plays a key role in adipogenesis. The interaction of endogenous SAV1 and PPARγ was detected in differentiating 3T3-L1 adipocytes. This binding required the kinase activity of MST2 and was mediated by the WW domains of SAV1 and the PPYY motif of PPARγ. Overexpression of MST2 and SAV1 increased PPARγ levels by stabilizing the protein, and the knockdown of SAV1 resulted in a decrease of endogenous PPARγ protein in 3T3-L1 adipocytes. During the differentiation of 3T3-L1 cells into adipocytes, MST2 and SAV1 expression began to increase at 2 days when PPARγ expression also begins to increase. MST2 and SAV1 significantly increased PPARγ transactivation, and SAV1 was shown to be required for the activation of PPARγ by rosiglitazone. Finally, differentiation of 3T3-L1 cells was augmented by MST2 and SAV1 expression and inhibited by knockdown of MST1/2 or SAV1. These results suggest that PPARγ activation by the MST signaling pathway may be a novel regulatory mechanism of adipogenesis.
Aim: The aim of this study was to investigate the association between the transcription factor 7-like 2 gene ( TCF7L2) rs7903146 polymorphism and peripheral arterial disease in type 2 diabetes. Methods: In total, 1818 Korean type 2 diabetes patients were enrolled from January 2013 to December 2017. Subjects were categorized into two groups according to their duration of type 2 diabetes: long (⩾10 years, n = 771) and short (<10 years, n = 1047) durations. A multivariate logistic regression model was used for assuming an additive effect on peripheral arterial disease for the presence of a variant allele in TCF7L2 rs7903146. Results: The frequency of the minor T-allele was 7.6% ( n = 139), and this allele was significantly associated with a 2.6-fold higher risk of peripheral arterial disease (odds ratio = 2.595, 95% confidence interval = 1.177–5.722, p = 0.018) in patients exhibiting a long duration of type 2 diabetes (⩾10 years). This result was significant after adjusting for age, sex, body mass index, familial history of diabetes, smoking, duration of diabetes and laboratory measurements, which included glycated haemoglobin, fasting plasma glucose and lipid profiles. In patients with diabetes < 10 years, there was no significant association between TCF7L2 rs7903146 and peripheral arterial disease (odds ratio = 1.233, 95% confidence interval = 0.492–3.093, p = 0.655). Conclusion: Our results provide evidence that genetic variation in TCF7L2 rs7903146 could increase risk for peripheral arterial disease in patients exhibiting long-standing type 2 diabetes.
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