Expression levels and functional aspects of the hyaluronan receptor CD44. Effects of insulin, glucose, IGF-I, or growth hormone on human arterial smooth muscle cells.
An increased amount of hyaluronan (HA) in the arterial wall is a feature of the diabetic macroangiopathy. The functional consequences of accumulated HA are mediated through binding to CD44. The regulation of this receptor by diabetic metabolic and hormonal factors is, however unknown. The objective of this study was to examine the influence of glucose, insulin, insulin-like growth factor I (IGF-I), and human growth hormone (hGH) on the formation and function of the HA receptor CD44 in cultures of human aortic smooth muscle cells (SMCs). Migration of nonproliferating SMCs were determined by estimating the area covered by cells 6 days after removal of a barrier. Cellular content of standard CD44 and its isoforms, CD44v3 and CD44v6, and HA-binding capacity were measured using a modified enzyme-linked immunosorbent assay procedure. The analysis is made either with antibodies against CD44 or with HA as a ligand. The migration assay showed that glucose, insulin, and IGF-I were able to stimulate SMC migration (2 P < .01). Anti-CD44 antibody inhibited the stimulated migration at most concentrations. Insulin increased HA binding at 100 to 1000 micro U/mL insulin (2 P < .03). CD44 expression was only elevated at 1000 micro U/mL insulin (2 P < .03), whereas CD44 content decreased at 2 ng/mL hGH and increased at 16 ng/mL hGH (2 P < .01). Glucose and IGF-I reduced the amount of the variant isoform CD44v3 (2 P < .01) but did not change the amount of total CD44. CD44v6 was not present on human arterial SMCs. In conclusion, the present data obtained with human arterial SMCs in vitro support a role of CD44 and its isoform, CD44v3, in the SMC response to the metabolic and hormonal disorders of diabetes.
Schultz
Kirsten
K
Research Laboratory for Biochemical Pathology, Aarhus Kommunehospital, DK-8000 Aarhus C, Denmark. kirsten@biokemiker.dk
Rasmussen
Lars Melholt
LM
Ledet
Thomas
T
D001011:Aorta; D015153:Blotting, Western; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D003925:Diabetic Angiopathies; D004797:Enzyme-Linked Immunosorbent Assay; D015870:Gene Expression / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology*; D019382:Human Growth Hormone / Q000494:pharmacology*; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics / Q000502:physiology*; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis
D018960:Hyaluronan Receptors; D007328:Insulin; D020033:Protein Isoforms; D012333:RNA, Messenger; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D005947:Glucose