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Human (h) growth hormone (GH) production studies are largely limited to effects on secretion. How pituitary hGH gene (hGH-N/GH1) expression is regulated is important in our understanding of the role hGH plays in physiology and disease. Here we assess for the first time the effect of sleep deprivation (SD) and high-fat diet (HFD) on hGH-N expression in vivo using partially humanized 171hGH/CS transgenic (TG) mice, and attempted to elucidate a role for DNA methylation. Activation of hGH-N expression requires interactions between promoter and upstream locus control region (LCR) sequences including pituitary-specific hypersensitive site (HS) I/II. Both SD and diet affect hGH secretion, but the effect of SD on hGH-N expression is unknown. Mice fed a HFD or regular chow diet for 3 days underwent SD (or no SD) for 6 h at Zeitgeber time (ZT) 3. Serum and pituitaries were assessed over 24 h at 6-h intervals beginning at ZT 14. SD and HFD caused significant changes in serum corticosterone and insulin, as well as hGH and circadian clock-related gene RNA levels. No clear association between DNA methylation and the negative effects of SD or diet on hGH RNA levels was observed. However, a correlation with increased methylation at a CpG (cytosine paired with a guanine) in a putative E-box within the hGH LCR HS II was suggested in situ. Methylation at this site also increased BMAL1/CLOCK-related nuclear protein binding in vitro. These observations support an effect of SD on hGH synthesis at the level of gene expression.
Department of Anatomy, Shanxi Medical University, Taiyuan, China
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Elucidating the mechanisms of regulation of β-cell proliferation is key to understanding the pathogenesis of diabetes mellitus. Txnip is a tumor suppressor that is upregulated in diabetes and plays an important role in the regulation of insulin sensitivity; however, its potential effect on pancreatic β-cell proliferation remains unclear. Here, we evaluated the role of Txnip in pancreatic β-cell compensatory proliferation by subjecting WT and Txnip knockout (KO) mice to a high-fat diet (HFD). Our results demonstrate that Txnip deficiency improves glucose tolerance and increases insulin sensitivity in HFD-induced obesity. The antidiabetogenic effect of Txnip deficiency was accompanied by increased β-cell proliferation and enhanced β-cell mass expansion. Furthermore, Txnip deficiency modulated the expression of a set of transcription factors with key roles in β-cell proliferation and cell cycle regulation. Txnip KO in HFD mice also led to activated levels of p-PI3K, p-AKT, p-mTOR and p-GSK3β, suggesting that Txnip may act via PI3K/AKT signaling to suppress β-cell proliferation. Thus, our work provides a theoretical basis for Txnip as a new therapeutic target for the treatment of diabetes mellitus.
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Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
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Background
Filamin A (FLNA) is a member of the filamin family and has been found to be critical for the progression of several cancers. However, its biological function in papillary thyroid cancer (PTC) remains largely unexplored.
Methods
Data from The Cancer Genome Atlas (TCGA) databases were utilized to analyze the FLNA expression level and its influence on the clinical implications of patients with PTC. Gene Expression Omnibus (GEO) and qRT-PCR was used to verify the expression levels of FLNA in PTC. Kaplan–Meier survival analysis was conducted to evaluate the prognostic value of FLNA in PTC. Transwell assays and wound healing were performed to examine the biological function of FLNA knockdown in PTC cells. Gene set enrichment analysis (GSEA) and Western blotting were conducted to investigate the potential mechanisms underlying the role of FLNA in PTC progression. In addition, the relationship between FLNA expression and the tumor immune microenvironment (TME) in PTC was explored.
Results
FLNA was significantly upregulated in PTC tissues. High expression levels of FLNA was correlated with advanced TNM stage, T stage, and N stage, as well as poor disease-free interval (DFI) and progression-free interval (PFI) time in PTC patients. Moreover, we found that FLNA knockdown inhibited the migration and invasion of PTC cells. Mechanistically, FLNA knockdown inhibited epithelial–mesenchymal transition (EMT) in PTC and affected the activation of the FAK/AKT signaling pathway. In addition, FLNA expression was associated with TME in PTC.
Conclusion
FLNA may be regarded as a new therapeutic target for PTC patients.
Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
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Department of Endocrinology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
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Objectives
A variety of factors differed between rural and urban areas may further influence iodine status and thyroid structure. Hence, this study compared iodine nutrition, the prevalence of thyroid goiter, and nodules between rural and urban residents in Guangzhou, a southern coastal city of China.
Methods
A total of 1211 rural residents and 1305 urban residents were enrolled in this cross-sectional study. A questionnaire regarding personal characteristics was administered. Urinary iodine concentration (UIC) was examined. Ultrasonography of the thyroid was performed to evaluate thyroid goiter and nodules. Multiple logistic analysis was used to identify the potential associated factors.
Results
The median UIC was significantly lower in rural residents than in urban residents (120.80 μg/L vs 136.00 μg/L, P < 0.001). Although the coverage rate of iodized salt was much higher in rural residents than in urban residents (99.59% vs 97.29%, P < 0.001), the percentages of seafood intake (8.60% vs 29.29%, P < 0.001), iodine-containing drug consumption (0.33% vs 1.24%, P = 0.011), and iodine contrast medium injection (0.58% vs 1.87%, P = 0.004) were lower in rural residents than in urban residents. Both the prevalence of thyroid goiters and nodules was significantly higher in rural residents than in urban residents (goiter: 8.06% vs 1.20%, P < 0.001; nodules: 61.89% vs 55.04%, P = 0.023). Living in rural areas was associated with thyroid goiter (OR 5.114, 95% CI 2.893–9.040, P < 0.001).
Conclusions
There were differences in iodine nutrition and the prevalence of thyroid goiter and nodules in rural and urban residents in Guangzhou. Differentiated and specialized monitoring is recommended in our area.
