IGF-dependent and IGF-independent actions of IGF-binding protein-1 and -2: implications for metabolic homeostasis

Trends Endocrinol Metab. 2009 May;20(4):153-62. doi: 10.1016/j.tem.2009.01.002. Epub 2009 Apr 6.

Abstract

Insulin-like growth factor (IGF)-binding proteins (IGFBPs) confer temporospatial regulation to IGF bioactivity. Both stimulatory and inhibitory effects of IGFBPs on IGF actions have been described, and IGF-independent effects of several IGFBPs are emerging. Accumulating evidence indicates important roles for members of the IGFBP family in metabolic homeostasis. For example, IGFBP-1 concentrations fluctuate inversely in response to changes in plasma insulin levels, implicating IGFBP-1 in glucoregulation, and fasting levels of IGFBP-1 predict insulin sensitivity at the population level. IGFBP-2 concentrations reflect long-term insulin sensitivity and are reduced in the presence of obesity. Here, we review the evolving roles of IGFBP-1 and IGFBP-2 in metabolic homeostasis, summarize their effects on IGF bioactivity and explore putative mechanisms by which they might exert IGF-independent cellular actions.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Homeostasis / physiology*
  • Humans
  • Insulin / blood
  • Insulin-Like Growth Factor Binding Protein 1 / metabolism
  • Insulin-Like Growth Factor Binding Protein 1 / physiology*
  • Insulin-Like Growth Factor Binding Protein 2 / metabolism
  • Insulin-Like Growth Factor Binding Protein 2 / physiology*
  • Models, Biological
  • Somatomedins / metabolism*

Substances

  • Insulin
  • Insulin-Like Growth Factor Binding Protein 1
  • Insulin-Like Growth Factor Binding Protein 2
  • Somatomedins