The expression of cyclin D1 during adipogenesis in pig primary stromal-vascular cultures

OBJECTIVE: Our objective in this study was to measure the expression of cyclin D1 in pig primary stromal-vascular (S-V) cells as they differentiate into adipose cells and to identify which factors may alter cyclin D1 expression. RESEARCH METHODS AND PROCEDURES: Western blot analysis was performed on cultured S-V cells using 8% sodium dodecyl sulfate-polyacrylamide gels, mouse monoclonal cyclin D1 antibody, and anti-mouse IgG secondary labeled with horseradish peroxidase. For immunocytochemistry, cultures were fixed with 4% paraformaldehyde and incubated with anti-CCAAT/enhancer binding protein (C/EBP alpha) and anti-cyclin D1 together. Cyclin D1 expression was evaluated in 105-day fetal dorsal subcutaneous tissues using paraffin sections. RESULTS: Our results with Western blot analysis showed that cyclin D1 was found in freshly isolated S-V cells and continued to be expressed during the first 3 days of adipose cell development with a significant increase in late development at day 9. Elevated cyclin D1 levels were colocalized with C/EBP alpha beginning at day 3 and remained colocalized with C/EBP alpha through day 9. Removing insulin from cultures resulted in a reduction in differentially elevated levels of cyclin D1. DISCUSSION: The elevated level of cyclin D1 expression colocalized with C/EBP alpha expression is unexpected because differentiated adipocytes would be expected to have reduced proliferative potential. The elevated levels of cyclin D1 expression we observed in mature adipocytes depend on insulin. In addition, cyclin D1 is absent from lipid-filled fetal adipose cells in vivo, where insulin levels are very low. The activity of cyclin D1 in differentiated adipocytes may be directed toward proteins outside of the cell cycle.     

Vitamin D and adipogenesis: new molecular insights

The focus of the current review is to highlight some new insights into the molecular mechanism by which vitamin D, a potentially nutritionally modulated factor, influences adipogenesis. Recent studies, predominantly using the mouse 3T3-L1 pre-adipocyte cell culture model, have shown that the role of vitamin D in inhibiting adipogenesis is mediated at the molecular level through a vitamin D receptor (VDR)-dependent inhibition of CCAAT enhancer binding protein-alpha (C/EBP alpha) and peroxisome proliferator-activated receptor-gamma (PPAR gamma) expression and a decrease in PPAR gamma transactivating activity in the pre-adipocyte. The latter action may reflect a vitamin D-induced decrease in endogenous PPAR gamma ligand availability and a competition between VDR and PPAR gamma for a limiting amount of retinoid X receptor (RXR), a common heterodimeric binding partner of both nuclear receptors.     

Pretreatment of starved rats with ornithine alpha-ketoglutarate: effects on hepatic mRNA levels and plasma concentrations of three liver-secreted proteins

OBJECTIVE: Ornithine alpha-ketoglutarate (OKG) displays anabolic properties at the hepatic level, but the mechanisms involved remain unclear. This study investigated in vivo the ability of OKG to modulate hepatic gene expression of three liver-secreted proteins: albumin, transthyretin, and retinol binding protein. METHODS: One hundred eighty rats were fed for 5 d with a balanced regimen enriched with OKG (5 g.kg(-1).d(-1)) or an isonitrogenous mixture (alanine, glycine, and serine). Hepatic mRNA levels and plasma concentrations of the three proteins studied were determined at the end of the nutrition period and after 1, 2, and 3 d of food deprivation. Results were compared by analysis of variance and Bonferroni-Dunn tests. RESULTS: At the end of the nutrition period, hepatic mRNA levels and plasma concentrations of the three proteins were not modified by OKG supplementation. However, OKG largely increased mRNA levels of albumin, transthyretin, and retinol binding protein on the first day of starvation compared with control animals (+68%, +64% and +51%, respectively; P < 0.01 versus control). OKG precociously increased albuminemia (on day 2) but had no effect on plasma concentrations of transthyretin and retinol binding protein. Neither regulation of polyamine hepatic concentration nor alteration in hepatic amino acid content seemed to be implicated in these actions. CONCLUSION: This study is the first to demonstrate that OKG regulates in vivo liver gene expression during acute malnutrition by modulating hepatic mRNA levels.     

维吾尔族宫颈鳞癌C/EBPα基因甲基化意义

目的探讨维吾尔族宫颈鳞癌C/EBPα基因（CCAAT/enhancer-binding proteinαgene）启动子区甲基化的意义。方法收集19例维吾尔族宫颈鳞癌组织和17例宫颈正常组织,提取基因组DNA,用基质辅助激光解吸附电离飞行时间质谱分析技术（MALDI-TOF）检测C/EBPα基因启动子区CpG岛甲基化状态。结果 （1）C/EBPα基因启动子区CpG岛甲基化程度在19例维吾尔族宫颈鳞癌病例组与17例对照组中各为（0.137 1±0.088 36）与（0.115 6±0.087 28）,差异有统计学意义（Z=-2.840,P=0.005）;（2）维吾尔族宫颈鳞癌病例组C/EBPα基因启动子区CpG₁、CpG₅和CpG₁4.15甲基化程度各为（0.095 9±0.053 16）（、0.072 1±0.025 07）和（0.261 3±0.050 83）,明显高于对照组的（0.068 1±0.076 09）（、0.044 7±0.026 25）和（0.191 7±0.070 69）,差异有统计学意义（P<0.05）;（3）患者年龄、高危型人类乳头瘤病毒16（HPV16）感染与C/EBPα基因启动子区CpG岛高甲基化状态无关（P>0.05）。结论 C/EBPα基因启动子区CpG岛、尤其是CpG₁、CpG₅和CpG₁4.15的高甲基化状态可能导致该基因沉默,从而促进维吾尔族宫颈鳞癌的发生发展。     

新疆维吾尔族妇女子宫颈鳞癌组织C/EBPβ基因单核苷酸多态性分析

目的:探讨新疆维吾尔族妇女子宫颈鳞癌组织C/EBPβ基因启动子500 bp和外显子区序列的单核苷酸多态性位点。方法:C/EBPβ基因启动子500 bp和外显子区域设计6对引物,使用聚合酶链反应结合DNA测序方法分析15例维吾尔族妇女子宫颈鳞癌组织和2例子宫颈正常组织C/EBPβ基因序列。结果:C/EBPβ基因上检测出6个已知SNP位点和3个新发现的或低频的多态性位点,有1例标本检测发现在2091-2092处插入GGCGGCAGC 9个碱基,而在维吾尔族正常子宫颈组织未发现新多态性位点。结论:C/EBPβ基因上新的多态性位点可能与维吾尔族子宫颈鳞癌发生相关。     

Protein-binding properties of 22-oxa-1 alpha,25-dihydroxyvitamin D3, a synthetic analogue of 1 alpha,25-dihydroxyvitamin D3

Protein binding properties of 22-oxa-1 alpha,25-dihydroxyvitamin D3 (22-oxa-1,25-D3), a synthetic analogue of 1 alpha,25-dihydroxyvitamin D3 (1,25-D3), were compared with those of vitamin D3 derivatives. The order of binding affinity to the chick embryonic intestinal receptor was 1,25-D3 greater than 22-oxa-1,25-D3 greater than 25-hydroxyvitamin D3 (25-D3) greater than 24R, 25-dihydroxyvitamin D3 (24, 25-D3) greater than vitamin D3 (D3), while that to the rat plasma vitamin D-binding protein (DBP) was 25-D3 greater than 24,25-D3 greater than D3 greater than 1,25-D3 greater than 22-oxa-1,25-D3. The binding potencies of 22-oxa-1,25-D3 to the receptor and DBP were about 1/8 and 1/600 of the respective values of 1,25-D3. When the distribution of the tritiated compounds in human plasma components was examined by an in vitro polyacrylamide gel electrophoretic method, [3H]-22-oxa-1,25-D3 was found to bind only to the lipoproteins including chyromicron. These results suggest that the replacement of a carbon atom into an oxygen atom in the side chain structure of 1,25-D3 results significant decrease in the binding affinity to DBP and that 22-oxa-1,25-D3 is transported as a complex-form not with DBP but with lipoprotein to the target tissues.     

The role of interleukin-1 beta in the regulation of liver-specific gene expression in human hepatoblastoma cells

The authors studied the function of liver cells--on level of DNA and gene regulation--by methods of molecular biology. They found that treating human hepatoma (Hep G2) cells with interleukin-1 (IL-1) leads to the induction of alpha-1-acidglycoprotein (AGP) and complement 3 (C3) mRNA synthesis, and to a concomitant downregulation of albumin (alb), alpha-fetoprotein (AFP) and alpha-2-macroglobulin (alpha 2M) mRNA synthesis. Levels of specific mRNA were measured by Northern-blot analysis. They conclude that Hep G2 cells may serve as a suitable in vitro model for study of the liver specific gene expression, and IL-1 is one of the mediators of these gene control. The regulation is pretranslational as the direction of change in specific mRNA corresponds to the changes in synthesis of the respective proteins.     

血管紧张素Ⅱ对前脂肪细胞分化相关转录因子表达的影响

目的探讨血管紧张素Ⅱ(angiotensin Ⅱ,AngⅡ)对前脂肪细胞分化过程中转录因子PPARγ、C/EBPα、SREBP1-c/ADD-1表达的调节从而研究AngⅡ调节前脂肪细胞分化可能的分子机制。方法 3T3-L1前脂肪细胞体外传代培养及诱导分化,用RT-PCR技术检测诱导分化过程中不同浓度AngⅡ处理6d对前脂肪细胞分化相关转录因子PPARγ、C/EBPα、SREBP1-c/ADD-1 mRNA表达水平的影响。结果 RT-PCR结果显示,100 nmol/L的AngⅡ处理细胞6 d后,PPARγ、C/EBPα、SREBP1-c/ADD-1 mRNA的相对表达量与对照组(AngⅡ添加浓度为0 nmol/L)有显著性差异(P<0.05),比对照组相应的转录因子分别增加了48%、50%、43%。结论前脂肪细胞分化过程中AngII能够上调PPARγ、C/EBPα、SREBP1-c/ADD-1 mRNA的表达量,AngⅡ可能通过影响PPARγ、C/EBPα和SREBP1-c/ADD-1的表达来调节前脂肪细胞的分化过程。