Cholecystokinin and Somatostatin Negatively Affect Growth of the Somatostatin-RIN-14B Cells

With the exclusive presence of the pancreatic CCK-2 receptors on the pancreatic delta cells of six different species, this study was undertaken to determine the role of cholecystokinin and gastrin on growth of these somatostatin (SS) cells. For this study, the SS-RIN-14B cells were used in culture and their growth was evaluated by cell counting. Results. To our surprise, we established by Western blot that these RIN cells possess the two CCK receptor subtypes, CCK-1 and CCK-2. Occupation of the CCK-1 receptors by caerulein, a CCK analog, led to inhibition of cell proliferation, an effect prevented by a specific CCK-1 receptor antagonist. Occupation of the CCK-2 receptors by the gastrin agonist pentagastrin had no effect on cell growth. Proliferation was not affected by SS released from these cells but was inhibited by exogenous SS. Conclusions. Growth of the SS-RIN-14B cells can be negatively affected by occupation of their CCK-1 receptors and by exogenous somatostatin

Identification and characterization of a triacylglycerol lipase in Arabidopsis homologous to mammalian acid lipases

AbstractTriacylglycerol (TAG) lipases have been thoroughly characterized in mammals and microorganisms. By contrast, very little is known on plant TAG lipases. An Arabidopsis cDNA called AtLip1 (At2g15230), which exhibits strong homology to lysosomal acid lipase, was found to drive the synthesis of an active TAG lipase when expressed in the baculovirus system. The lipase had a maximal activity at pH 6 and the specific activity was estimated to be about 45μmolmin−1mg−1 protein using triolein as a substrate. Knock-out mutant analysis showed no phenotype during germination indicating that this enzyme is fully dispensable for TAG storage breakdown during germination. Northern blot analyses indicated that the transcript is present in all tissues tested

Identification et caractérisation d'une lipase chez Arabidopsis thaliana

AIX-MARSEILLE2-BU Sci.Luminy (130552106) / SudocSudocFranceF

Deletion of the gene encoding G0/G1 switch protein 2 (G0s2) alleviates high-fat-diet-induced weight gain and insulin resistance, and promotes browning of white adipose tissue in mice

Conclusions/interpretation: Our data show that G0s2 is a physiological regulator of adiposity and energy metabolism and is a potential target in the treatment of obesity and insulin resistance.Results: We report that G0s2 inhibits ATGL and regulates lipolysis and energy metabolism in vivo. G0s2−/− mice are lean, resistant to weight gain induced by a high-fat diet and are glucose tolerant and insulin sensitive. The white adipose tissue of G0s2−/− mice has enhanced lipase activity and adipocytes showed enhanced stimulated lipolysis. Energy metabolism in the G0s2−/− mice is shifted towards enhanced lipid metabolism and increased thermogenesis. G0s2−/− mice showed enhanced cold tolerance and increased expression of thermoregulatory and oxidation genes within white adipose tissue, suggesting enhanced ‘browning’ of the white adipose tissue.Aims/hypothesis: Obesity is a global epidemic resulting from increased energy intake, which alters energy homeostasis and results in an imbalance in fat storage and breakdown. G0/G1 switch gene 2 (G0s2) has been recently characterised in vitro as an inhibitor of adipose triglyceride lipase (ATGL), the rate-limiting step in fat catabolism. In the current study we aim to functionally characterise G0s2 within the physiological context of a mouse model.Methods: We generated a mouse model in which G0s2 was deleted. The homozygous G0s2 knockout (G0s2−/−) mice were studied over a period of 22 weeks. Metabolic variables were measured including body weight and body composition, food intake, glucose and insulin tolerance tests, energy metabolism and thermogenesis

Deletion of the gene encoding G0/G 1 switch protein 2 (G0s2) alleviates high-fat-diet-induced weight gain and insulin resistance, and promotes browning of white adipose tissue in mice

AIMS/HYPOTHESIS: Obesity is a global epidemic resulting from increased energy intake, which alters energy homeostasis and results in an imbalance in fat storage and breakdown. G0/G1 switch gene 2 (G0s2) has been recently characterised in vitro as an inhibitor of adipose triglyceride lipase (ATGL), the rate-limiting step in fat catabolism. In the current study we aim to functionally characterise G0s2 within the physiological context of a mouse model. METHODS: We generated a mouse model in which G0s2 was deleted. The homozygous G0s2 knockout (G0s2 (-/-)) mice were studied over a period of 22 weeks. Metabolic variables were measured including body weight and body composition, food intake, glucose and insulin tolerance tests, energy metabolism and thermogenesis. RESULTS: We report that G0s2 inhibits ATGL and regulates lipolysis and energy metabolism in vivo. G0s2 (-/-) mice are lean, resistant to weight gain induced by a high-fat diet and are glucose tolerant and insulin sensitive. The white adipose tissue of G0s2 (-/-) mice has enhanced lipase activity and adipocytes showed enhanced stimulated lipolysis. Energy metabolism in the G0s2 (-/-) mice is shifted towards enhanced lipid metabolism and increased thermogenesis. G0s2 (-/-) mice showed enhanced cold tolerance and increased expression of thermoregulatory and oxidation genes within white adipose tissue, suggesting enhanced \u27browning\u27 of the white adipose tissue. CONCLUSIONS/INTERPRETATION: Our data show that G0s2 is a physiological regulator of adiposity and energy metabolism and is a potential target in the treatment of obesity and insulin resistance