Characterisation of receptors for IGF-I and insulin: evidence for hybrid insulin/IGF-I receptor in human coronary artery endothelial cells
2006 (English)In: Growth Hormone & IGF Research, ISSN 1096-6374, Vol. 16, no 4, 258-266 p.Article in journal (Refereed) Published
Objective: Coronary artery disease is a prevalent cause of morbidity and mortality in diabetes. Little is known about insulin-like growth factor-I receptors (IGF-IR) and insulin receptors (IR) in human coronary endothelium. Our aim was to characterize IGF-IR and IR in human coronary artery endothelial cells (HCAEC).
Design: Cultured human coronary artery endothelial cells were used. Gene expression was measured by quantitative real-time RTPCR analysis and receptor affinity by ligand binding. Receptor protein, phosphorylation of IGF-IR and IR b-subunit as well as the presence of hybrid insulin receptor/Insulin-like growth factor-I receptor (Hybrid IR/IGF-IR) was analyzed by immunoprecipitation and Western blot. Postreceptor effects of insulin and IGF-I were assed by 3H-thymidine incorporation.
Results: The gene expression of IGF-IR was several folds higher than that of IR. and insulin receptor isoform A (IR-A) was 20-fold more expressed than insulin receptor isoform B (IR-B) in HCAEC. The specific binding of 125I-IGF-I was higher than that of 125Iinsulin. Insulin and the new long acting insulin analog, glargine, interacted with the IGF-IR with over thousand and 100-fold less potency than IGF-I itself, whereas IGF-II had 6 times lower potency than IGF-I. Phosphorylation of the IGF-IR b-subunit was obtained by concentrations of 10-10–10-8 M IGF-I, 10-6 M of insulin, inconsistently by 10-8 M insulin and not at all by 10-10–10-9 M insulin. The IR b-subunit was phosphorylated by insulin and IGF-I at concentrations of 10-9–10-8 M. When immunoprecipitating with specific monoclonal anti-IR or anti-IGF-IR a-subunit antibodies we found bands situated in slightly different positions suggesting the presence of Hybrid IR/IGF-IR. IGF-I, IGF-II and insulin (10-9–10-7 M) had no significant effect on 3H-thymidine incorporation into DNA.
Conclusions: Human coronary endothelial cells express more IGF-IR than IR, mainly IR-A, and also Hybrid IR/IGF-IR. Both IGF-I and insulin phosphorylate their receptors, but only IGF-I seems to phosphorylate Hybrid IR/IGF-IR. Our study provides experimental evidence for a possible role of IGF-IR, IR and Hybrid IR/IGF-IR in human coronary artery endothelial cells.
Place, publisher, year, edition, pages
2006. Vol. 16, no 4, 258-266 p.
Human endothelial cells; Insulin-like growth factor-I; Insulin
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-12555DOI: 10.1016/j.ghir.2006.06.003ISI: 000240947800006OAI: oai:DiVA.org:liu-12555DiVA: diva2:1694