Actions of IGF binding proteins and related proteins in adipose tissue.
The insulin-like growth factors (IGFs), their binding proteins (IGFBPs) and structurally related proteins have been identified in adipose tissue but their roles in adipose tissue are poorly understood. IGF-I and IGFBP-3 expression increase during human preadipocyte differentiation. However, whereas IGF-I stimulates this process, IGFBP-3 is inhibitory both to preadipocyte differentiation and to differentiated adipocyte function. The direct interaction of IGFBP-3 with peroxisome proliferator-activated receptor-gamma is believed to contribute to its inhibitory effect on differentiation. Connective tissue growth factor (CTGF/CCN2) shares weak structural homology and functional similarities with IGFBP-3, including inhibition of preadipocyte differentiation. This review examines the current knowledge of IGFBP regulation and actions in adipocytes and proposes a common regulatory pathway involving IGFBP-3 and CTGF/CCN2.
Baxter
Robert C
RC
Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St. Leonards NSW 2065, Australia. robaxter@med.usyd.edu.au
Twigg
Stephen M
SM
D050156:Adipogenesis / Q000502:physiology; D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D055513:Connective Tissue Growth Factor / Q000378:metabolism; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism*; D008954:Models, Biological; D011485:Protein Binding / Q000502:physiology; D015398:Signal Transduction
D018969:Insulin-Like Growth Factor Binding Proteins; D055513:Connective Tissue Growth Factor