Characteristics of binding of insulin-like growth factor (IGF)-I and IGF-II analogues to the type 1 IGF receptor determined by BIAcore analysis.
Insulin-like growth factor (IGF) binding to the type 1 IGF receptor (IGF1R) elicits mitogenic effects, promotion of differentiation and protection from apoptosis. This study has systematically measured IGF1R binding affinities of IGF-I, IGF-II and 14 IGF analogues to a recombinant high-affinity form of the IGF1R using BIAcore technology. The analogues assessed could be divided into two groups: (a) those designed to investigate binding of IGF-binding protein, which exhibited IGF1R-binding affinities similar to those of IGF-I or IGF-II; (b) those generated to probe IGF1R interactions with greatly reduced IGF1R-binding affinities. The relative binding affinities of IGF-I analogues and IGF-I for the IGF1R determined by BIAcore analysis agreed closely with existing data from receptor-binding assays using cells or tissue membranes, demonstrating that BIAcore technology is a powerful tool for measuring affinities of IGFs for IGF1R. In parallel studies, IGF1R-binding affinities were related to ability to protect against serum withdrawal-induced apoptosis in three different assays including Hoechst 33258 staining, cell survival, and DNA fragmentation assays using the rat pheochromocytoma cell line, PC12. In this model system, IGF-I and IGF-II at low nanomolar concentrations are able to prevent apoptosis completely. We conclude that ability to protect against apoptosis is directly related to ability to bind the IGF1R.
Forbes
Briony E
BE
Department of Molecular Biosciences, Adelaide University, SA Australia. briony.forbes@adelaide.edu.au
Hartfield
Perry J
PJ
McNeil
Kerrie A
KA
Surinya
Kathy H
KH
Milner
Steven J
SJ
Cosgrove
Leah J
LJ
Wallace
John C
JC
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015374:Biosensing Techniques; D006224:Cricetinae; D007334:Insulin-Like Growth Factor I / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D016716:PC12 Cells; D051381:Rats; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D017526:Receptor, IGF Type 1