scholarly journals Calpain System Regulates the Differentiation of Adult Primitive Mesenchymal ST-13 Adipocytes

Endocrinology ◽  
2006 ◽  
Vol 147 (10) ◽  
pp. 4811-4819 ◽  
Author(s):  
Yukiko Yajima ◽  
Mayumi Sato ◽  
Hiroyuki Sorimachi ◽  
Mitsushi Inomata ◽  
Masatoshi Maki ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Binding Protein ◽  
Regulatory Element ◽  
Clonal Expansion ◽  
Dominant Negative ◽  
Nuclear Fraction ◽  
Element Binding Protein ◽  
Sterol Regulatory Element ◽  
Mitotic Clonal Expansion ◽  
Calpain System

The activity of calpain, a calcium-activated protease, is required during the mitotic clonal expansion phase of 3T3-L1 embryonic preadipocyte differentiation. Here we examined the role of calpain in the adipogenesis of ST-13 preadipocytes established from adult primitive mesenchymal cells, which do not require mitotic clonal expansion. After exposure to the calpain inhibitor, N-benzyloxycarbonyl-l-leucyl-l-leucinal or overexpression of calpastatin, a specific endogenous inhibitor of calpain, ST-13 preadipocytes acquired the adipocyte phenotype. Overexpression of calpastatin in ST-13 adipocytes stimulated the expression of adipocyte-specific CCAAT/enhancer-binding protein-α (C/EBPα), peroxisome proliferator-activated receptor (PPAR)-γ, sterol regulatory element-binding protein 1, and the insulin signaling molecules, insulin receptor α, insulin-receptor substrates, and GLUT4. However, insulin-stimulated glucose uptake was reduced by approximately 52%. The addition of calpain to the nuclear fraction of ST-13 adipocytes resulted in the Ca2+-dependent degradation of PPARγ and C/EBPα but not sterol regulatory element-binding protein 1. Exposing ST-13 adipocytes to A23187 also led to losses of endogenous PPARγ and C/EBPα. Under both conditions, calpain inhibitors almost completely prevented C/EBPα cleavage but partially blocked the decrease of PPARγ. Two ubiquitous forms of calpain, μ- and m-calpain, localized to the cytosol and the nucleus, whereas the activated form of μ- but not m-calpain was found in the nucleus. Finally, stable dominant-negative μ-calpain transfectants showed accelerated adipogenesis and increase in the levels of PPARγ and C/EBPα during adipocyte program. These results support evidence that the calpain system is involved in regulating the differentiation of adult primitive mesenchymal ST-13 preadipocytes.

scholarly journals Progesterone Stimulates Adipocyte Determination and Differentiation 1/Sterol Regulatory Element-binding Protein 1c Gene Expression

2001 ◽  
Vol 276 (15) ◽  
pp. 11512-11516 ◽  
Author(s):  
Danièle Lacasa ◽  
Xavier Le Liepvre ◽  
Pascal Ferre ◽  
Isabelle Dugail
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid Synthase ◽  
Binding Protein ◽  
Regulatory Element ◽  
Cancer Cell Line ◽  
Dominant Negative ◽  
Transcriptional Level ◽  
Dominant Negative Form ◽  
Element Binding Protein ◽  
Sterol Regulatory Element

Fatty acid synthase (FAS), a nutritionally regulated lipogenic enzyme, is transcriptionally controlled by ADD1/SREBP1c (adipocyte determination and differentiation 1/sterol regulatory element-binding protein 1c), through insulin-mediated stimulation of ADD1/SREBP1c expression. Progesterone exerts lipogenic effects on adipocytes, and FAS is highly induced in breast tumor cell lines upon progesterone treatment. We show here that progesterone up-regulates ADD1/SREBP1c expression in the MCF7 breast cancer cell line and the primary cultured preadipocyte from rat parametrial adipose tissue. In MCF7, progesterone induced ADD1/SREBP1c and Metallothionein II (a well known progesterone-regulated gene) mRNAs, with comparable potency. In preadipocytes, progesterone increased ADD1/SREBP1c mRNA dose-dependently, but not SREBP1a or SREBP2. Run-on experiments demonstrated that progesterone action on ADD1/SREBP1c was primarily at the transcriptional level. The membrane-bound and mature nuclear forms of ADD1/SREBP1 protein accumulated in preadipocytes cultured with progesterone, and FAS induction could be abolished by adenovirus-mediated overexpression of a dominant negative form of ADD1/SREBP1 in these cells. Finally, in the presence of insulin, progesterone was unable to up-regulate ADD1/SREBP1c mRNA in preadipocytes, whereas its effect was restored after 24 h of insulin deprivation. Together these results demonstrate that ADD1/SREBP1c is controlled by progesterone, which, like insulin, acts by increasing ADD1/SREBP1c gene transcription. This provides a potential mechanism for the lipogenic actions of progesterone on adipose tissue.

Resistance to high-fat diet-induced obesity and altered expression of adipose-specific genes in HSL-deficient mice

2003 ◽  
Vol 285 (6) ◽  
pp. E1182-E1195 ◽  
Author(s):  
Kenji Harada ◽  
Wen-Jun Shen ◽  
Shailja Patel ◽  
Vanita Natu ◽  
Jining Wang ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Insulin Receptor ◽  
Binding Protein ◽  
Regulatory Element ◽  
Mrna Levels ◽  
High Fat ◽  
Diet Induced Obesity ◽  
Element Binding Protein ◽  
Sterol Regulatory Element ◽  
Adipose Differentiation

To elucidate the role of hormone-sensitive lipase (HSL) in diet-induced obesity, HSL-deficient ( HSL– /–) and wild-type mice were fed normal chow or high-fat diets. HSL– /– mice were resistant to diet-induced obesity showing higher core body temperatures. Weight and triacylglycerol contents were decreased in white adipose tissue (WAT) but increased in both brown adipose tissue (BAT) and liver of HSL– /– mice. Serum insulin levels in the fed state and tumor necrosis factor-α mRNA levels in adipose tissues were higher, whereas serum levels of adipocyte complement-related protein of 30 kDa (ACRP30)/adiponectin and leptin, as well as mRNA levels of ACRP30/adiponectin, leptin, resistin, and adipsin in WAT, were lower in HSL– /– mice than in controls. Expression of transcription factors associated with adipogenesis (peroxisome proliferator-activated receptor-γ, CAAT/enhancer-binding protein-α) and lipogenesis (carbohydrate response element-binding protein, adipocyte determination- and differentiation-dependent factor-1/sterol regulatory element-binding protein-1c), as well as of adipose differentiation markers (adipocyte lipid-binding protein, perilipin, lipoprotein lipase), lipogenic enzymes (glycerol-3-phosphate acyltransferase, acyl-CoA:diacylglycerol acyltransferase-1 and -2, fatty acid synthase, ATP citrate lyase) and insulin signaling proteins (insulin receptor, insulin receptor substrate-1, GLUT4), was suppressed in WAT but not in BAT of HSL– /– mice. In contrast, expression of genes associated with cholesterol metabolism (sterol-regulatory element-binding protein-2, 3-hydroxy-3-methylglutaryl-CoA reductase, acyl-CoA:cholesterol acyltransferase-1) and thermogenesis (uncoupling protein-2) was upregulated in both WAT and BAT of HSL– /– mice. Our results suggest that impaired lipolysis in HSL deficiency affects lipid metabolism through alterations of adipose differentiation and adipose-derived hormone levels.

scholarly journals Increased Expression of the Sterol Regulatory Element-binding Protein-1 Gene in Insulin Receptor Substrate-2−/−Mouse Liver

2001 ◽  
Vol 276 (42) ◽  
pp. 38337-38340 ◽  
Author(s):  
Kazuyuki Tobe ◽  
Ryo Suzuki ◽  
Masashi Aoyama ◽  
Toshimasa Yamauchi ◽  
Junji Kamon ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Mouse Liver ◽  
Binding Protein ◽  
Regulatory Element ◽  
Insulin Receptor Substrate ◽  
Element Binding Protein ◽  
Sterol Regulatory Element

scholarly journals Dual Effect of the Adapter Growth Factor Receptor-Bound Protein 14 (Grb14) on Insulin Action in Primary Hepatocytes

Endocrinology ◽  
2008 ◽  
Vol 149 (6) ◽  
pp. 3109-3117 ◽  
Author(s):  
Nadège Carré ◽  
Michèle Caüzac ◽  
Jean Girard ◽  
Anne-Françoise Burnol
Keyword(s):  
Gene Expression ◽  
Growth Factor ◽  
Insulin Receptor ◽  
Insulin Action ◽  
Binding Protein ◽  
Regulatory Element ◽  
Growth Factor Receptor ◽  
Element Binding Protein ◽  
Sterol Regulatory Element ◽  
Growth Factor Receptor Bound

Tight control of insulin action in liver is a crucial determinant for the regulation of energy homeostasis. Growth factor receptor-bound protein 14 (Grb14) is a molecular adapter, highly expressed in liver, which binds to the activated insulin receptor and inhibits its tyrosine kinase activity. The physiological role of Grb14 in liver metabolism was unexplored. In this study we used RNA interference to investigate the consequences of Grb14 decrease on insulin-regulated intracellular signaling, and on glucose and lipid metabolism in mouse primary cultured hepatocytes. In Grb14-depleted hepatocytes, insulin-induced phosphorylation of Akt, and of its substrates glycogen synthase kinase 3 and fork-head box protein 1, was increased. These effects on insulin signaling are in agreement with the selective inhibitory effect of Grb14 on the receptor kinase. However, the metabolic and genic effects of insulin were differentially regulated after Grb14 down-regulation. Indeed, the insulin-mediated inhibition of hepatic glucose production and gluconeogenic gene expression was slightly increased. Surprisingly, despite the improved Akt pathway, the induction by insulin of sterol regulatory element binding protein-1c maturation was totally blunted. As a result, in the absence of Grb14, glycogen synthesis as well as glycolytic and lipogenic gene expression were not responsive to the stimulatory effect of insulin. This study provides evidence that Grb14 exerts a dual role on the regulation by insulin of hepatic metabolism. It inhibits insulin receptor catalytic activity, and acts also at a more distal step, i.e. sterol regulatory element binding protein-1c maturation, which effect is predominant under short-term inhibition of Grb14 expression.

scholarly journals Hairpin Orientation of Sterol Regulatory Element-binding Protein-2 in Cell Membranes as Determined by Protease Protection

1995 ◽  
Vol 270 (49) ◽  
pp. 29422-29427 ◽  
Author(s):  
Xianxin Hua ◽  
Juro Sakai ◽  
Ho Y. K. ◽  
Joseph L. Goldstein ◽  
Michael S. Brown
Keyword(s):  
Cell Membranes ◽  
Binding Protein ◽  
Regulatory Element ◽  
Element Binding Protein ◽  
Sterol Regulatory Element

scholarly journals Sterol Regulatory Element Binding Protein 1a Regulates Hepatic Fatty Acid Partitioning by Activating Acetyl Coenzyme A Carboxylase 2

2009 ◽  
Vol 29 (17) ◽  
pp. 4864-4872 ◽  
Author(s):  
Seung-Soon Im ◽  
Linda E. Hammond ◽  
Leyla Yousef ◽  
Cherryl Nugas-Selby ◽  
Dong-Ju Shin ◽  
...  
Keyword(s):  
Insertional Mutagenesis ◽  
Coenzyme A ◽  
Binding Protein ◽  
Regulatory Element ◽  
Fatty Acyl ◽  
Acetyl Coenzyme A ◽  
Acetyl Coenzyme ◽  
Element Binding Protein ◽  
Sterol Regulatory Element ◽  
Microarray Expression

ABSTRACT We generated a line of mice in which sterol regulatory element binding protein 1a (SREBP-1a) was specifically inactivated by insertional mutagenesis. Homozygous mutant mice were completely viable despite expressing SREBP-1a mRNA below 5% of normal, and there were minimal effects on expression of either SREBP-1c or -2. Microarray expression studies in liver, where SREBP-1a mRNA is 1/10 the level of the highly similar SREBP-1c, demonstrated that only a few genes were affected. The only downregulated genes directly linked to lipid metabolism were Srebf1 (which encodes SREBP-1) and Acacb (which encodes acetyl coenzyme A [acetyl-CoA] carboxylase 2 [ACC2], a critical regulator of fatty acyl-CoA partitioning between cytosol and mitochondria). ACC2 regulation is particularly important during food restriction. Similar to Acacb knockout mice, SREBP-1a-deficient mice have lower hepatic triglycerides and higher serum ketones during fasting than wild-type mice. SREBP-1a and -1c have identical DNA binding and dimerization domains; thus, the failure of the more abundant SREBP-1c to substitute for activating hepatic ACC2 must relate to more efficient recruitment of transcriptional coactivators to the more potent SREBP-1a activation domain. Our chromatin immunoprecipitation results support this hypothesis.

scholarly journals Analysis of the role of protein kinase B (cAKT) in insulin-dependent induction of glucokinase and sterol regulatory element-binding protein 1 (SREBP1) mRNAs in hepatocytes

2003 ◽  
Vol 376 (3) ◽  
pp. 697-705 ◽  
Author(s):  
Pascale G. RIBAUX ◽  
Patrick B. IYNEDJIAN
Keyword(s):  
Protein Kinase ◽  
Protein Kinase B ◽  
Binding Protein ◽  
Regulatory Element ◽  
Necessary Condition ◽  
Insulin Effect ◽  
Element Binding Protein ◽  
Insulin Dependent ◽  
Sterol Regulatory Element ◽  
Stimulation Of

Previous work showed that acute stimulation of a conditionally active protein kinase B (PKB or cAKT) was sufficient to elicit insulin-like induction of GCK (glucokinase) and SREBP1 (sterol regulatory element-binding protein 1) in hepatocytes [Iynedjian, Roth, Fleischmann and Gjinovci (2000) Biochem. J. 351, 621–627; Fleischmann and Iynedjian (2000) Biochem. J. 349, 13–17]. The objective of the present study was to determine whether activation of PKB during insulin stimulation of hepatocytes was a necessary condition for the induction of the two genes. Activation of PKB by insulin was inhibited by pretreatment of the hepatocytes with C2 ceramide. This resulted in the inhibition of insulin-dependent increases in GCK and SREBP1 mRNAs. A triple mutant of PKB failed to interfere with insulin activation of PKB in hepatocytes even at high overexpression levels achieved after adenovirus transduction. A PKB–CaaX fusion protein, which can act as a dominant-negative inhibitor of PKB activation in other cells, was shown to be constitutively activated in hepatocytes and to trigger insulin-like induction of GCK and SREBP1. In addition, constitutive PKB–CaaX activity caused refractoriness of the hepatocytes to insulin signalling at an upstream step resulting in the inhibition of both extracellular-signal-regulated kinase 1/2 and endogenous PKB activation. The stimulation of gene expression by constitutively active PKB–CaaX and inhibition of the insulin effect by ceramide are compatible with a role for PKB in the insulin-dependent induction of GCK and SREBP1.

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