Tweeters, Woofers and Horns: The Complex Orchestration of Calcium Currents in T Lymphocytes

摘要

Elevation of intracellular calcium ion (Ca~(2+)) levels is a vital event that regulates T lymphocyte homeostasis, activation, proliferation, differentiation, and apoptosis. The mechanisms that regulate intracellular Ca~(2+)signaling in lymphocytes involve tightly controlled concinnity of multiple ion channels, membrane receptors, and signaling molecules. T cell receptor (TCR) engagement results in depletion of endoplasmic reticulum (ER) Ca~(2+)stores and subsequent sustained influx of extracellular Ca~(2+)through Ca~(2+)release-activated Ca~(2+)(CRAC) channels in the plasma membrane. This process termed store-operated Ca~(2+)entry (SOCE) involves the ER Ca~(2+)sensing molecule, STIM1, and a pore-forming plasma membrane protein, ORAI1. However, several other important Ca~(2+)channels that are instrumental in T cell function also exist. In this review, we discuss the role of additional Ca~(2+)channel families expressed on the plasma membrane of T cells that likely contribute to Ca~(2+)influx following TCR engagement, which include the TRP channels, the NMDA receptors, the P2X receptors, and the IP_(3)receptors, with a focus on the voltage-dependent Ca~(2+)(Ca_(V)) channels.