Structural and functional characterization of the human T lymphocyte receptor for insulin-like growth factor I in vitro.
AUTOR(ES)
Tapson, V F
RESUMO
Growth factor receptors for T lymphocytes, such as interleukin 2 and insulin, are present on activated but not resting T lymphocytes. We sought to determine if insulin-like growth factor I (IGF-I) could act as a growth factor for human T cells and to characterize its receptor on resting and activated cells. Recombinant IGF-I induced two separate functions. It was chemotactic for and increased incorporation of tritiated thymidine into both unactivated (resting) and mitogen-activated T cells. High-affinity 125I-IGF-I binding to human T cells was saturable with an apparent Kd of 1.2 +/- .6 X 10(-10) M for binding to activated T cells and 1.2 +/- .9 X 10(-10) for unactivated T cells. The calculated binding for activated cells was 330 +/- 90 and for resting cells 45 +/- 9 high-affinity receptor sites per cell. Affinity cross-linking of 125I-IGF-I to resting or activated T cells revealed a radioligand-receptor complex of 360,000 mol wt when analyzed by SDS-PAGE without reduction and complexes of 270,000 and 135,000 mol wt upon reduction; prior incubation with excess unlabeled IGF-I prevented formation of the 125I-IGF-I receptor complex. Our data suggest that both resting and activated T lymphocytes bear functional IGF-I receptors similar to those found in other tissues. These receptors may mediate T cell growth and chemotaxis.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=303607Documentos Relacionados
- The trophic action of growth hormone, insulin-like growth factor-I, and insulin on human duodenal mucosa cultured in vitro.
- The receptor for insulin-like growth factor II mediates an insulin-like response.
- Growth-stimulatory monoclonal antibodies against human insulin-like growth factor I receptor.
- A functional insulin-like growth factor I receptor is required for the mitogenic and transforming activities of the epidermal growth factor receptor.
- Isolation of the human insulin-like growth factor genes: insulin-like growth factor II and insulin genes are contiguous.