Role of insulin and IGF-I receptors in human cardiac microvascular endothelial cells; metabolic, mitogenic and anti-inflammatory effects
(English)Manuscript (preprint) (Other academic)
Diabetes is associated with coronary microcirculatory dysfunction and heart failure as well as changes in insulin and IGF-I levels. Our aim was to study the role of insulin receptors and IGF-I receptors in metabolic, mitogenic and anti-inflammatory responses to insulin and IGF-I in human cardiac microvascular endothelial cells (HMVEC-C) and, for comparison, also human umbilical vein endothelial cells (HUVEC). Insulin receptor (IR) and IGF-I receptor (IGF-IR) gene expression was studied with real-time RT-PCR. Receptor protein expression and phosphorylation was determined with Western blot and ELISA. The metabolic and mitogenic effects were measured as glucose accumulation and thymidine incorporation. An E-selectin ELISA was used to investigate the anti-inflammatory responses. IGF-IR was more abundant than IR both regarding gene expression and protein in HMVEC-C and HUVEC. Immunoprecipitation with anti-IGF-IR antibody and immunoblotting with anti-IR antibody and vice versa, showed insulin/IGF-I hybrid receptors in these cells. IGF-I 10-8 M significantly stimulated phosphorylation of both IGF-IR and IR in HMVEC-C. In HUVEC IGF-I 10-8 M phosphorylated IGF-IR. IGF-I also stimulated DNA synthesis at 10-8 M and glucose accumulation at 10-7 M. TNF-α significantly increased E-selectin expression whereas no effects were found by insulin, IGF-I or high glucose.
We conclude that HMVEC-C express more IGF-I receptors than insulin receptors and at physiological concentrations of insulin and IGF-I mainly reacts to IGF-I probably due to the predominance of IGF-I receptors and insulin/IGF-I hybrid receptors. TNF-α has a pronounced pro-inflammatory effect in HMVEC-C which is not counteracted by insulin or IGF-I.
receptor ELISA, thymidine incorporation, glucose accumulation, E-selectin expression
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:liu:diva-71890OAI: oai:DiVA.org:liu-71890DiVA: diva2:455197