Activation of Ca2+/Calmodulin-dependent Protein Kinase (CaM-kinase) IV by CaM-kinase Kinase in Jurkat T Lymphocytes

In-Kyung Park,Thomas R Soderling

doi:10.1074/jbc.270.51.30464

In-Kyung Park, Thomas R Soderling

Open Access

https://doi.org/10.1074/jbc.270.51.30464

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Abstract

Ca2+/calmodulin-dependent protein kinase IV (CaM-kinase IV), a member of the CaM-kinase family involved in transcriptional regulation, is stimulated by Ca2+/CaM but also requires phosphorylation by a CaM-kinase kinase for full activation. In this study we investigated the physiological role of a CaM-kinase cascade in Jurkat T human lymphocytes through antigen receptor (CD3) signaling. Total and Ca(2+)-independent CaM-kinase IV activities were increased 8-14-fold by anti-CD3 antibody. This CD3-mediated activation involved phosphorylation since the immunoprecipitated CaM-kinase IV from stimulated Jurkat cells could be subsequently inactivated in vitro by protein phosphatase 2A. CaM-kinase IV immunoprecipitated from unstimulated Jurkat cells or CD3-negative mutant Jurkat cells could be activated in vitro 10-40-fold by CaM-kinase kinase purified from rat brain or thymus, whereas CaM-kinase IV from CD3-stimulated wild-type Jurkat cells was only activated to 2-3-fold by exogenous CaM-kinase kinase. CaM-kinase IV activation was triggered by Ca2+ acting through calmodulin since activation could also be elicited by ionomycin treatment, and CD3-mediated activation was blocked by the calmodulin antagonist calmidazolium. These data are consistent with a CaM-kinase cascade in which CaM-kinase IV is activated by a CaM-kinase kinase cascade triggered by elevated intracellular calcium in Jurkat cells.

Highlights

The primary structure of CaM-kinase IV has been resolved by cDNA cloning from rat [1, 13, 14] and mouse brain [15] and human Jurkat T lymphocytes [16]
It was originally thought that CaM-kinase IV is activated by autophosphorylation since the enzyme purified from rat brain and thymus exhibits 10-fold or greater increases in both total and Ca2ϩ-independent activities upon incubation in the presence of Ca2ϩ/CaM and ATP/Mg2ϩ [2, 20, 21]
CaM-kinase IV might be involved in T cell development since it is more abundant in immature thymocytes compared with mature thymocytes and circulating T lymphocytes, and it is not expressed in B lymphocytes or monocytes [25]

Summary

Introduction

The primary structure of CaM-kinase IV has been resolved by cDNA cloning from rat [1, 13, 14] and mouse brain [15] and human Jurkat T lymphocytes [16]. In Jurkat T lymphocytes, both Ca2ϩ-independent and total activities of CaM-kinase IV are maximally increased within 1 min of stimulation of the CD3 receptor [25].

Results

Conclusion