CTRP9 transgenic mice are protected from diet-induced obesity and metabolic dysfunction

Jonathan M. Peterson, Zhikui Wei, Marcus M. Seldin, Mardi S. Byerly, Susan Aja, G. William Wong

Research output: Contribution to journalArticle

Abstract

CTRP9 is a secreted multimeric protein of the C1q family and the closest paralog of the insulin-sensitizing adipokine, adiponectin. The metabolic function of this adipose tissue-derived plasma protein remains largely unknown. Here, we show that the circulating levels of CTRP9 are downregulated in diet-induced obese mice and upregulated upon refeeding. Overexpressing CTRP9 resulted in lean mice that dramatically resisted weight gain induced by a high-fat diet, largely through decreased food intake and increased basal metabolism. Enhanced fat oxidation in CTRP9 transgenic mice resulted from increases in skeletal muscle mitochondrial content, expression of enzymes involved in fatty acid oxidation (LCAD and MCAD), and chronic AMPK activation. Hepatic and skeletal muscle triglyceride levels were substantially decreased in transgenic mice. Consequently, CTRP9 transgenic mice had a greatly improved metabolic profile with markedly reduced fasting insulin and glucose levels. The high-fat diet-induced obesity, insulin resistance, and hepatic steatosis observed in wild-type mice were prevented in transgenic mice. Consistent with the in vivo data, recombinant protein significantly enhanced fat oxidation in L6 myotubes via AMPK activation and reduced lipid accumulation in H4IIE hepatocytes. Collectively, these data establish CTRP9 as a novel metabolic regulator and a new component of the metabolic network that links adipose tissue to lipid metabolism in skeletal muscle and liver.

Original languageEnglish (US)
Pages (from-to)R522-R533
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume305
Issue number5
DOIs
StatePublished - Sep 1 2013

Keywords

  • AMPK
  • C1q family
  • Energy metabolism
  • Fatty acid oxidation
  • Obesity
  • Type 2 diabetes

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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