Critical role for the β regulatory subunits of Cav channels in T lymphocyte function

doi:10.1073/pnas.0607262103

Critical role for the β regulatory subunits of Cav channels in T lymphocyte function

*Section of Immunobiology,
^§Howard Hughes Medical Institute, and
^†Section of Digestive Diseases, Yale University School of Medicine, New Haven, CT 06510; and
^‡Experimentelle und Klinische Pharmakologie und Toxikologie, Universität des Saarlandes, Gebäude 46, D-66421 Homburg, Germany

Contributed by Richard A. Flavell, August 23, 2006

Abstract

Calcium ion is a universal signaling intermediate, which is known to control various biological processes. In excitable cells, voltage-gated calcium channels (Cav) are the major route of calcium entry and regulate multiple functions such as contraction, neurotransmitter release, and gene transcription. Here we show that T lymphocytes, which are nonexcitable cells, express both regulatory β and pore-forming Cav1 α1 subunits of Cav channels, and we provide genetic evidence for a critical role of the Cav β3 and Cav β4 regulatory subunits in T lymphocyte function. Cav β-deficient T lymphocytes fail to acquire normal functions, and they display impairment in the T cell receptor-mediated calcium response, nuclear factor of activated T cells activation, and cytokine production. In addition, unlike in excitable cells, our data suggest a minimal physiological role for depolarization in Cav channel opening in T cells. T cell receptor stimulation induces only a small depolarization of T cells, and artificial depolarization of T cells using KCl does not lead to calcium entry. These observations suggest that the Cav channels expressed by T cells have adopted novel regulation/gating mechanisms.

Footnotes

^¶To whom correspondence should be addressed. E-mail: richard.flavell{at}yale.edu
Author contributions: A.B. and M.K.J. contributed equally to this work; A.B., M.K.J., and R.A.F. designed research; A.B., M.K.J., D.M., and W.Z.M. performed research; M.F. and V.F. contributed new reagents/analytic tools; A.B., M.K.J., D.M., and R.A.F. analyzed data; and A.B., M.K.J., and R.A.F. wrote the paper.
The authors declare no conflict of interest.
↵ ‖ Some of the data presented in this article were initially published in Science (43) and were subsequently retracted (44) because of the erroneous nature of figure 4B, which was prepared by Srisaila Basavappa. In this article, in addition to the analysis of the β4 mutant mice, we present new evidence corroborating the role of the Cav channels in T lymphocyte functions by using Cav β3 KO mice. Therefore, this previously unpublished genetic evidence is compatible with the genetic evidence previously published in the Science article (i.e., β4 mutant mice) and emphasizes a more generalized role for the Cav β subunits in T cell functions.
Abbreviations:

TCR,

T cell receptor;

DiBAC4,

bis-(1,3-dibutylbarbituric acid) trimethine oxonol;

NFAT,

nuclear factor of activated T cells;

KO,

knockout.