Related Experiment Videos
Different induction of p55 and p70/75 interleukin-2 receptor subunits in human cells
T Tanaka1, S Kishimoto, O Saiki
1Third Department of Internal Medicine, Osaka University, Japan.
Insights
Interleukin-2 receptor (IL-2R) subunits p55 and p70/75 are differentially regulated. Calcium-calmodulin pathways primarily influence p70/75 expression, while protein kinase-C (PK-C) pathways affect p55 expression in human lymphocytes.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Human lymphocytes express two key interleukin-2 receptor (IL-2R) subunits: p55 (also known as Tac or alpha chain) and p70/75 (also known as beta and gamma common chains).
- Interleukin-2 (IL-2) signaling is crucial for T cell proliferation, differentiation, and immune regulation, mediated through these IL-2R subunits.
Purpose of the Study:
- To investigate the differential regulation of IL-2R p55 and p70/75 subunit expression on human lymphocytes.
- To elucidate the roles of distinct intracellular signaling pathways, specifically calcium-calmodulin and protein kinase-C (PK-C), in controlling IL-2R subunit expression.
Main Methods:
- Utilized chemical crosslinking studies to assess IL-2R subunit expression.
- Employed binding assays to quantify IL-2R subunit interactions and expression levels.
- Stimulated human T and B cells with phorbol myristate acetate (PMA), a PK-C activator, and ionomycin (IM), a calcium ionophore.
Main Results:
- Ionomycin (IM) predominantly induced the expression of the p70/75 IL-2R subunit on both T and B lymphocytes.
- Phorbol myristate acetate (PMA) significantly induced the expression of the p55 IL-2R subunit.
- Differential induction patterns suggest distinct regulatory mechanisms for each IL-2R subunit.
Conclusions:
- The calcium-calmodulin and PK-C signaling pathways differentially regulate the expression of IL-2R p70/75 and p55 subunits, respectively.
- These intracellular signaling pathways can modulate lymphocyte responsiveness to IL-2 by altering the affinity and number of available IL-2 receptors in vivo.
Abstract:
There are two interleukin-2 receptor (IL-2R) subunits (p55 and p70/75) on human lymphocytes. Induction of the expressions of these IL-2R subunits was examined by the protein kinase-C (PK-C) activator (phorbol myristate acetate, PMA) and the calcium ionophore, ionomycine (IM). IM induced predominantly p70/75 expression on human T and B cells as indicated by the results of chemical crosslinking studies and binding assays. In contrast, PMA induced p55 expression significantly. These results suggest that the calcium-calmodulin and PK-C pathways regulate p70/75 and p55 expressions differently, and indicate that these intracellular signal messengers could control the responsiveness to IL-2, changing the affinity and number of receptors in vivo.