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The Insulin-Like Growth Factor System and the Coupling of Formation to Resorption

J M Hayden, S Mohan, D J Baylink

Bone. 1995 Aug;17(2 Suppl):93S-98S.

PMID: 8579905

Abstract:

In the adult skeleton, bone formation is regulated by an event referred to as the coupling of formation to resorption (i.e., formation is linked to resorption), which is thought to be mediated in part by locally produced growth factors. Although human bone cells produce and human bones contain a variety of growth factors, there is sufficient evidence to document an important role for the insulin-like growth factor (IGF) system in mediating this coupling process in bone. Studies on the basic aspects of the IGF system in bone reveal that it is complex and involves a number of components which include the IGF-binding proteins (IGFBPs; mainly IGFBP-3, -4, and -5), specific extracellular IGFBP proteases, and receptors (types 1 and 2). Based on recent experimental evidence from a number of laboratories, we propose the following models of IGF action on the regulation of the coupled increase in bone formation in response to bone resorption: (1) IGF release from bone during bone resorption promotes osteoblasts to initiate cavity refilling; (2) IGF production by osteoclasts creates a population of osteoblasts in proportion to the volume of bone tissue resorbed; and (3) IGF production by stromal cells and osteoblasts predominantly regulates the extent of cavity refill. The amount of growth factor production by osteoblasts and contemporary cells of osteoblast lineage can be further controlled by both systemic and local factors which together determine the eventual level of fill-in of the resorption cavity.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
IAR4248605 Insulin-like Growth Factor-II human Insulin-like Growth Factor-II human Price
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