Modulation of plasma membrane calcium-ATPase activity by local calcium microdomains near CRAC channels in human T cells

J Physiol. 2004 May 1;556(Pt 3):805-17. doi: 10.1113/jphysiol.2003.060004. Epub 2004 Feb 13.

Abstract

The spatial distribution of Ca(2+) signalling molecules is critical for establishing specific interactions that control Ca(2+) signal generation and transduction. In many cells, close physical coupling of Ca(2+) channels and their targets enables precise and robust activation of effector molecules through local [Ca(2+)](i) elevation in microdomains. In T cells, the plasma membrane Ca(2+)-ATPase (PMCA) is a major target of Ca(2+) influx through Ca(2+) release-activated Ca(2+) (CRAC) channels. Elevation of [Ca(2+)](i) slowly modulates pump activity to ensure the stability and enhance the dynamic nature of Ca(2+) signals. In this study we probed the functional organization of PMCA and CRAC channels in T cells by manipulating Ca(2+) microdomains near CRAC channels and measuring the resultant modulation of PMCAs. The amplitude and spatial extent of microdomains was increased by elevating the rate of Ca(2+) entry, either by raising extracellular [Ca(2+)], by increasing the activity of CRAC channels with 2-aminoethoxyborane (2-APB), or by hyperpolarizing the plasma membrane. Surprisingly, doubling the rate of Ca(2+) influx does not further increase global [Ca(2+)](i) in a substantial fraction of cells, due to a compensatory increase in PMCA activity. The enhancement of PMCA activity without changes in global [Ca(2+)](i) suggests that local [Ca(2+)](i) microdomains near CRAC channels effectively promote PMCA modulation. These results reveal an intimate functional association between CRAC channels and Ca(2+) pumps in the plasma membrane which may play an important role in governing the time course and magnitude of Ca(2+) signals in T cells.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Algorithms
  • Boron Compounds / pharmacology
  • Calcium / metabolism*
  • Calcium / pharmacology
  • Calcium Channel Agonists / pharmacology
  • Calcium Channels / drug effects
  • Calcium Channels / physiology*
  • Calcium-Transporting ATPases / metabolism*
  • Cation Transport Proteins
  • Fura-2 / chemistry
  • Humans
  • Jurkat Cells
  • Lanthanum / pharmacology
  • Membrane Potentials / physiology
  • Microscopy, Fluorescence
  • Models, Biological
  • Patch-Clamp Techniques
  • Plasma Membrane Calcium-Transporting ATPases
  • T-Lymphocytes / drug effects
  • T-Lymphocytes / metabolism
  • T-Lymphocytes / physiology*
  • Thapsigargin / pharmacology

Substances

  • Boron Compounds
  • Calcium Channel Agonists
  • Calcium Channels
  • Cation Transport Proteins
  • Thapsigargin
  • Lanthanum
  • 2-aminoethoxydiphenyl borate
  • Plasma Membrane Calcium-Transporting ATPases
  • Calcium-Transporting ATPases
  • Calcium
  • Fura-2