Germline ablation of VGF increases lipolysis in white adipose tissue

J Endocrinol. 2012 Nov;215(2):313-22. doi: 10.1530/JOE-12-0172. Epub 2012 Aug 31.

Abstract

Targeted deletion of VGF, a neuronal and endocrine secreted protein and neuropeptide precursor, produces a lean, hypermetabolic mouse that is resistant to diet-, lesion-, and genetically induced obesity and diabetes. We hypothesized that increased sympathetic nervous system activity in Vgf-/Vgf- knockout mice is responsible for increased energy expenditure and decreased fat storage and that increased β-adrenergic receptor stimulation induces lipolysis in white adipose tissue (WAT) of Vgf-/Vgf- mice. We found that fat mass was markedly reduced in Vgf-/Vgf- mice. Within knockout WAT, phosphorylation of protein kinase A substrate increased in males and females, phosphorylation of hormone-sensitive lipase (HSL) (ser563) increased in females, and levels of adipose triglyceride lipase, comparative gene identification-58, and phospho-perilipin were higher in male Vgf-/Vgf- WAT compared with wild-type, consistent with increased lipolysis. The phosphorylation of AMP-activated protein kinase (AMPK) (Thr172) and levels of the AMPK kinase, transforming growth factor β-activated kinase 1, were decreased. This was associated with a decrease in HSL ser565 phosphorylation, the site phosphorylated by AMPK, in both male and female Vgf-/Vgf- WAT. No significant differences in phosphorylation of CREB or the p42/44 MAPK were noted. Despite this evidence supporting increased cAMP signaling and lipolysis, lipogenesis as assessed by fatty acid synthase protein expression and phosphorylated acetyl-CoA carboxylase was not decreased. Our data suggest that the VGF precursor or selected VGF-derived peptides dampen sympathetic outflow pathway activity to WAT to regulate fat storage and lipolysis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue, White / metabolism*
  • Animals
  • Body Composition
  • Body Weight
  • Fatty Acids, Nonesterified / metabolism
  • Female
  • Gene Expression Regulation / physiology
  • Lipogenesis / physiology
  • Lipolysis / genetics
  • Lipolysis / physiology*
  • Male
  • Mice
  • Mice, Knockout
  • Nerve Growth Factors
  • Neuropeptides / genetics
  • Neuropeptides / metabolism*
  • Phosphorylation

Substances

  • Fatty Acids, Nonesterified
  • Nerve Growth Factors
  • Neuropeptides
  • Vgf protein, mouse