Coordinate regulation by transcription factors and DNA methylation in the core promoter region of SIRT6 in bovine adipocytes.

Sirtuin6 (SIRT6) is an ADP-ribosyltransferase and NAD+-dependent deacylase of acetyl groups and long-chain fatty acyl groups, and has been shown as a regulator of insulin secretion, glucose metabolism, lipid metabolism, and cancer. In this study, we determined that the bovine SIRT6 showed higher levels of mRNA expression in the testis, longissimus thoracis, and subcutaneous fat tissue. To elucidate the molecular regulation mechanism of bovine SIRT6 expression, we obtained a 2-kb fragment containing the 5'-regulatory region, and the functional proximal minimal promoter of bovine SIRT6 was identified in the -472/-73 bp region. The CCAAT enhancer binding protein beta (CEBPß), paired box 6 (PAX6), Kruppel-like factor 2 (KLF2), myb proto-oncogene protein (CMYB), nuclear respiratory factor 1 (NRF1), and E2F transcription factor 1 (E2F1) binding sites, as transcriptional activators or repressors in the core promoter region of SIRT6, were determined by electrophoretic mobility shift assay (EMSA) experiments and luciferase reporter assays. In addition, the results from methylation assay and luciferase report assay showed that the bovine SIRT6 promoter activity was coordinately regulated by methylation and NRF1 or E2F1 during bovine adipocyte differentiation. Taken together, this study illuminated the underlying mechanism of methylation and transcription regulation of SIRT6 expression in bovine adipocytes.

Myocyte enhancer factor 2A promotes proliferation and its inhibition attenuates myogenic differentiation via myozenin 2 in bovine skeletal muscle myoblast.

Myocyte enhancer factor 2A (MEF2A) is widely distributed in various tissues or organs and plays crucial roles in multiple biological processes. To examine the potential effects of MEF2A on skeletal muscle myoblast, the functional role of MFE2A in myoblast proliferation and differentiation was investigated. In this study, we found that the mRNA expression level of Mef2a was dramatically increased during the myogenesis of bovine skeletal muscle primary myoblast. Overexpression of MEF2A significantly promoted myoblast proliferation, while knockdown of MEF2A inhibited the proliferation and differentiation of myoblast. RT-PCR and western blot analysis revealed that this positive effect of MEF2A on the proliferation of myoblast was carried out by triggering cell cycle progression by activating CDK2 protein expression. Besides, MEF2A was found to be an important transcription factor that bound to the myozenin 2 (MyoZ2) proximal promoter and performed upstream of MyoZ2 during myoblast differentiation. This study provides the first experimental evidence that MEF2A is a positive regulator in skeletal muscle myoblast proliferation and suggests that MEF2A regulates myoblast differentiation via regulating MyoZ2.

TNFRSF11B polymorphisms are associated with metabolic traits in Uyghur and Han ethnic groups.

UNLABELLED: Abstract Introduction: To test whether genetic variants of osteoprotegerin gene (TNFRSF11B) affect metabolic traits (body mass index [BMI], glucose, triglyceride, total cholesterol) and bone mass traits. METHODS: We conducted a population based association study to investigate associations of eight tagging single nucleotide polymorphisms (tSNPs) of the TNFRSF11B gene with the aforementioned traits in a Chinese Han population and an ethnic group admixed with Caucasians and Asians - Uyghur. The associations between the tSNPs and bone mass density (BMD) were also tested in Han population. RESULTS: We found that SNP rs3102727, located in the first intron of the TNFRSF11B gene, was significantly associated with triglyceride levels in Uyghur population and Han population simultaneously. T allele of the rs3102727 variant was associated with a 0.10 mmol/L and 0.09 mmol/L lower level of triglyceride than C allele in Uyghur (p = 0.019) and Han subjects (p = 0.037), respectively. In addition, the T allele is also associated with a lower level of hip BMD (p = 0.025) and total BMD (p = 0.048). Further, we found significant associations between SNP rs11573869 and BMI in Uyghur subjects and SNP rs3134062 with hip BMD in Han sbujects. Rs11573869-T allele was associated with a 0.81 kg/m(2) lower level of BMI than C allele (p = 0.002) and the hip BMD decreases with the copy of rs3134062-T allele increases (p = 0.002). CONCLUSION: We detected novel associations between TNFRSF11B polymorphisms and metabolic traits in Uyghur and Han populations. In addition, we found associations between TNFRSF11B polymorphisms and bone mass traits in Han population.

[Value of adrenal venous sampling in the subtype diagnosis of primary aldosteronism].

OBJECTIVE: To assess the diagnostic value of adrenal venous sampling (AVS) in the subtype diagnosis of primary aldosteronism (PA). METHODS: The diagnosis of PA was made in 36 patients based on an elevated ratio of plasma aldosterone (ALD) to plasma rennin activity (PRA) (ARR) and confirmed tests (saline infusion or captopril challenge) in recent 3 years. All PA patients underwent adrenal computed tomographic scan (CT) and AVS. The diagnostic accuracy of CT and AVS in the subtype differentiation of PA were evaluated by comparing the differences of CT findings, AVS results and clinical outcomes. RESULTS: Fifteen of 36 patients (42%) had a final diagnosis of aldosterone-producing adenoma (APA) and another 21 patients (58%) with bilateral adrenal hyperplasia (BAH). The level of ALD was significantly higher in APA group than that in BAH group (298.9 ± 91.0 vs 226.3 ± 59 ng/L, P < 0.05). PRA (ng×ml(-1)×h(-1)) in APA patients were markedly lower than that in BAH counterparts (0.18 ± 0.14 vs 0.28 ± 0.29 ng×ml(-1)×h(-1), P < 0.01). Consequently, ARR in APA group was evidently higher than that in BAH group (2444.7 ± 1405.2 vs 1550.0 ± 1059.8, P < 0.05). Plasma potassium in APA patients was lower than that in those with BAH (2.71 ± 0.57 vs 3.17 ± 0.40 mmol/L). But there was no statistic significance (P > 0.05). The CT findings were discordant with the AVS results in 27.8% of patients (10/36). The accuracy of adrenal CT scan was only 72.2% in the subtype diagnosis of PA, provided AVS was the gold standard for distinguishing between APA and BAH. Reliance on CT findings could lead to inappropriate management in 25% of PA patients. Conversely, the AVS results were concordant with the clinical outcomes in 94.4% of all patients. CONCLUSION: CT scan is not a reliable method of differentiating primary aldosteronism. Compared with CT, AVS is more accurate in establishing a correct diagnosis of primary aldosteronism. AVS should be performed routinely before operation in PA patients opting for adrenalectomy.

Profiling of chicken adipose tissue gene expression by genome array.

BACKGROUND: Excessive accumulation of lipids in the adipose tissue is a major problem in the present-day broiler industry. However, few studies have analyzed the expression of adipose tissue genes that are involved in pathways and mechanisms leading to adiposity in chickens. Gene expression profiling of chicken adipose tissue could provide key information about the ontogenesis of fatness and clarify the molecular mechanisms underlying obesity. In this study, Chicken Genome Arrays were used to construct an adipose tissue gene expression profile of 7-week-old broilers, and to screen adipose tissue genes that are differentially expressed in lean and fat lines divergently selected over eight generations for high and low abdominal fat weight. RESULTS: The gene expression profiles detected 13,234-16,858 probe sets in chicken adipose tissue at 7 weeks, and genes involved in lipid metabolism and immunity such as fatty acid binding protein (FABP), thyroid hormone-responsive protein (Spot14), lipoprotein lipase(LPL), insulin-like growth factor binding protein 7(IGFBP7) and major histocompatibility complex (MHC), were highly expressed. In contrast, some genes related to lipogenesis, such as leptin receptor, sterol regulatory element binding proteins1 (SREBP1), apolipoprotein B(ApoB) and insulin-like growth factor 2(IGF2), were not detected. Moreover, 230 genes that were differentially expressed between the two lines were screened out; these were mainly involved in lipid metabolism, signal transduction, energy metabolism, tumorigenesis and immunity. Subsequently, real-time RT-PCR was performed to validate fifteen differentially expressed genes screened out by the microarray approach and high consistency was observed between the two methods. CONCLUSION: Our results establish the groundwork for further studies of the basic genetic control of growth and development of chicken adipose tissue, and will be beneficial in clarifying the molecular mechanism of obesity in chickens.