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B56alpha/protein phosphatase 2A inhibits adipose lipolysis in high-fat diet-induced obese mice.

ABSTRACT: Lipolysis and lipogenesis are two opposite processes that control lipid storage in adipocytes. Impaired adipose lipolysis has been observed in both obese human subjects and animal models. This study investigated the mechanisms underlying impaired adipose lipolysis in a high-fat diet-induced obese (DIO) mouse model. DIO models were created using male C57BL/6 mice. Our results show that beta3 adrenergic receptor-specific agonist BRL37344 induced adipose lipolysis was significantly blunted in DIO mice. The levels of Ser660 phosphorylation of hormone-sensitive lipase (HSL) were significantly decreased in the epididymal fat of DIO mice. However, protein levels of HSL, adipose triglyceride lipase and its coactivator comparative gene identification-58 were similar between DIO and control mice. It is known that upon lipolytic hormone stimulation, protein kinase A phosphorylates HSL Ser660 and activates HSL, whereas protein phosphatase 2A (PP2A) dephosphorylates and inactivates HSL. Interestingly, our study shows that high-fat feeding did not alter epididymal fat cAMP and protein kinase A protein levels but significantly increased the expression of the alpha-isoform of PP2A regulatory subunit B' (B56alpha). To study the role of B56alpha in obesity-associated lipolytic defect, B56alpha was overexpressed or knocked down by adenovirus-mediated gene transduction in cultured 3T3-L1CARDelta1 adipocytes. Overexpression of B56alpha significantly decreased HSL Ser660 phosphorylation. In contrast, knocking down B56alpha increased hormone-stimulated HSL activation and lipolysis in mature 3T3-L1CARDelta1 adipocytes. These results strongly suggest that elevated B56alpha/PP2A inhibits HSL and lipolysis in white adipose tissue of DIO mice.

SUBMITTER: Kinney BP

PROVIDER: S-EPMC2940515 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

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B56alpha/protein phosphatase 2A inhibits adipose lipolysis in high-fat diet-induced obese mice.

Kinney Brice P BP Qiao Liping L Levaugh Justin M JM Shao Jianhua J

Endocrinology 20100609 8

Lipolysis and lipogenesis are two opposite processes that control lipid storage in adipocytes. Impaired adipose lipolysis has been observed in both obese human subjects and animal models. This study investigated the mechanisms underlying impaired adipose lipolysis in a high-fat diet-induced obese (DIO) mouse model. DIO models were created using male C57BL/6 mice. Our results show that beta3 adrenergic receptor-specific agonist BRL37344 induced adipose lipolysis was significantly blunted in DIO m ...[more]

PMID: 20534721

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Project description:ObjectiveA sexual dimorphism exists in body fat distribution; females deposit relatively more fat in subcutaneous/inguinal depots whereas males deposit more fat in the intra-abdominal/gonadal depot. Our objective was to systematically document depot- and sex-related differences in the accumulation of adipose tissue and gene expression, comparing differentially expressed genes in diet-induced obese mice with mice maintained on a chow diet.Research design and methodsWe used a microarray approach to determine whether there are sexual dimorphisms in gene expression in age-matched male, female or ovariectomized female (OVX) C57/BL6 mice maintained on a high-fat (HF) diet. We then compared expression of validated genes between the sexes on a chow diet.ResultsAfter exposure to a high fat diet for 12 weeks, females gained less weight than males. The microarray analyses indicate in intra-abdominal/gonadal adipose tissue in females 1642 genes differ by at least twofold between the depots, whereas 706 genes differ in subcutaneous/inguinal adipose tissue when compared with males. Only 138 genes are commonly regulated in both sexes and adipose tissue depots. Inflammatory genes (cytokine-cytokine receptor interactions and acute-phase protein synthesis) are upregulated in males when compared with females, and there is a partial reversal after OVX, where OVX adipose tissue gene expression is more 'male-like'. This pattern is not observed in mice maintained on chow. Histology of male gonadal white adipose tissue (GWAT) shows more crown-like structures than females, indicative of inflammation and adipose tissue remodeling. In addition, genes related to insulin signaling and lipid synthesis are higher in females than males, regardless of dietary exposure.ConclusionsThese data suggest that male and female adipose tissue differ between the sexes regardless of diet. Moreover, HF diet exposure elicits a much greater inflammatory response in males when compared with females. This data set underscores the importance of analyzing depot-, sex- and steroid-dependent regulation of adipose tissue distribution and function.

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B56alpha/protein phosphatase 2A inhibits adipose lipolysis in high-fat diet-induced obese mice.

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B56alpha/protein phosphatase 2A inhibits adipose lipolysis in high-fat diet-induced obese mice.

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