Downregulation of insulin-like growth factor-1 receptor (IGF-1R) expression in human T lymphocyte activation.
Although it is known that IGF-1 increases T lymphocyte proliferation, the regulation of its receptor expression during the process has not been defined. Consequently the regulation of IGF-1R expression by IGF-1 and the activation events in human blood T lymphocytes and the Jurkat T cell line were now investigated. IGF-1R expression in nonstimulated Jurkat cells was confirmed and downregulation by IGF-1 was demonstrated. In addition, both cell types showed a time-dependent reduction in the number of IGF-1R-positive cells following activation, which was increased by IGF-1. In Jurkat cells the negative regulation of IGF-1R levels was correlated with the appearance and continuous increase in IL-2R. In T lymphocytes the decrease in IGF-1R expression was faster, reaching its plateau after 3 h of activation. Our findings suggest that loss of the IGF-1R is one of the initial events of the activation process not regulated by IL-2.
Schillaci
R
R
Instituto de Biología y Medicina Experimental, CONICET, Buenos Aires, Argentina.
Brocardo
M G
MG
Galeano
A
A
Roldán
A
A
D015536:Down-Regulation; D005434:Flow Cytometry; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D017526:Receptor, IGF Type 1 / Q000096:biosynthesis*; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*
D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1