Role of Ca2+ in the regulation of hormone receptor exposure during lymphocyte activation

W. Jy, N. Fregien, G. J. Bourguignon, Lilly Y.W. Bourguignon

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Ca2+ is known to be required for mitogen-mediated lymphocyte activation. In order to further define the regulatory role of Ca2+, we have examined the activation events which occur following treatment with ionomycin (a Ca2+ ionophore), as compared to those occurring following concanavalin A (Con A) treatment of mouse splenic T-lymphocytes. Our results indicate that ionomycin and Con A induce the exposure of both interleukin-2 (IL-2) and insulin receptors on the surface of the lymphocytes within the first 5 min of treatment. The exposed insulin and IL-2 receptors have the following properties: (1) they consists of both high- and low-affinity receptors; and (2) they appear on the cell surface in small clusters (i.e., patches) or, occasionally, a large aggregate (i.e., cap). c-myc gene expression and DNA synthesis occur in both the ionomycin and Con A-treated lymphocytes when either IL-2 or insulin is present in the culture medium. Furthermore, the exposure of both hormone receptors can be inhibited by either EGTA (a Ca2+ chelator), bepridil (a Ca2+ channel blocker), W-7 (a calmodulin antagonist) or cytochalasin D (a microfilament inhibitor). Treatment with these inhibitors also blocks the expression of c-myc gene and DNA synthesis which occur at later times during IL-2 and insulin-induced activation of ionomycin- and Con A-treated lymphocytes. These findings suggest that a Ca2+ and calmodulin-mediated contractile system is involved in the exposure of certain hormone receptors which appear to be required for complete lymphocyte activation.

Original languageEnglish (US)
Pages (from-to)153-160
Number of pages8
JournalBBA - Biomembranes
Volume983
Issue number2
DOIs
StatePublished - Aug 7 1989

Keywords

  • Calcium ion
  • Calcium ionophore
  • Calmodulin
  • Hormone receptor
  • Ionomycin
  • Lymphocyte activation
  • Mitogenesis

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology
  • Medicine(all)

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