G s α deficiency in the dorsomedial hypothalamus leads to obesity, hyperphagia, and reduced thermogenesis associated with impaired leptin signaling

Mol Metab. 2019 Jul;25:142-153. doi: 10.1016/j.molmet.2019.04.005. Epub 2019 Apr 12.

Abstract

Objective: Gsα couples multiple receptors, including the melanocortin 4 receptor (MC4R), to intracellular cAMP generation. Germline inactivating Gsα mutations lead to obesity in humans and mice. Mice with brain-specific Gsα deficiency also develop obesity with reduced energy expenditure and locomotor activity, and impaired adaptive thermogenesis, but the underlying mechanisms remain unclear.

Methods: We created mice (DMHGsKO) with Gsα deficiency limited to the dorsomedial hypothalamus (DMH) and examined the effects on energy balance and thermogenesis.

Results: DMHGsKO mice developed severe, early-onset obesity associated with hyperphagia and reduced energy expenditure and locomotor activity, along with impaired brown adipose tissue thermogenesis. Studies in mice with loss of MC4R in the DMH suggest that defective DMH MC4R/Gsα signaling contributes to abnormal energy balance but not to abnormal locomotor activity or cold-induced thermogenesis. Instead, DMHGsKO mice had impaired leptin signaling along with increased expression of the leptin signaling inhibitor protein tyrosine phosphatase 1B in the DMH, which likely contributes to the observed hyperphagia and reductions in energy expenditure, locomotor activity, and cold-induced thermogenesis.

Conclusions: DMH Gsα signaling is critical for energy balance, thermogenesis, and leptin signaling. This study provides insight into how distinct signaling pathways can interact to regulate energy homeostasis and temperature regulation.

Keywords: G protein; Hypothalamus; Obesity; Sympathetic nervous system; Thermogenesis.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Adipose Tissue, Brown / metabolism
  • Animals
  • Energy Metabolism / physiology
  • GTP-Binding Protein alpha Subunits, Gs / genetics*
  • GTP-Binding Protein alpha Subunits, Gs / metabolism*
  • Gene Expression Regulation
  • Genetic Predisposition to Disease / genetics
  • Glucose / metabolism
  • Homeostasis / physiology
  • Hyperphagia / metabolism*
  • Hypothalamus / metabolism*
  • Leptin / metabolism*
  • Male
  • Mice
  • Mice, Knockout
  • Obesity / genetics
  • Obesity / metabolism*
  • Protein Tyrosine Phosphatase, Non-Receptor Type 1 / metabolism
  • Receptor, Melanocortin, Type 4 / metabolism
  • Signal Transduction / physiology*
  • Sympathetic Nervous System / metabolism
  • Thermogenesis / physiology*

Substances

  • Leptin
  • MC4R protein, mouse
  • Receptor, Melanocortin, Type 4
  • Protein Tyrosine Phosphatase, Non-Receptor Type 1
  • Ptpn1 protein, mouse
  • GTP-Binding Protein alpha Subunits, Gs
  • Glucose