Role of IGF-I signaling in muscle bone interactions

• IGF-I has both endocrine and local production.
• IGF-I has direct growth effects on skeletal muscle and bone.
• IGF-I has indirect effects on bone via its direct actions on muscle.
• Synergy of IGF-I and mechanical crosstalk creates potential therapeutic strategies.

Skeletal muscle and bone rely on a number of growth factors to undergo development, modulate growth, and maintain physiological strength. A major player in these actions is insulin-like growth factor I (IGF-I). However, because this growth factor can directly enhance muscle mass and bone density, it alters the state of the musculoskeletal system indirectly through mechanical crosstalk between these two organ systems. Thus, there are clearly synergistic actions of IGF-I that extend beyond the direct activity through its receptor. This review will cover the production and signaling of IGF-I as it pertains to muscle and bone, the chemical and mechanical influences that arise from IGF-I activity, and the potential for therapeutic strategies based on IGF-I.This article is part of a Special Issue entitled “Muscle Bone Interactions”.