The short isoform of extended synaptotagmin-2 controls Ca2+ dynamics in T cells via interaction with STIM1

Sci Rep. 2020 Sep 2;10(1):14433. doi: 10.1038/s41598-020-71489-7.

Abstract

Ca2+ release-activated Ca2+ (CRAC) channels elevate cytoplasmic Ca2+ concentration, which is essential for T cell activation, differentiation and effector functions. T cell receptor stimulation induces depletion of the endoplasmic reticulum (ER) Ca2+ stores, which is sensed by stromal interaction molecule 1 (STIM1). STIM1 translocates to the ER-plasma membrane (PM) junctions to interact with ORAI1, the pore subunit of the CRAC channels. Here, we show that two members of the extended synaptotagmin (E-Syt) family, E-Syt1, and the short isoform of E-Syt2 (E-Syt2S), contribute to activation of CRAC channels in T cells. Knockdown or deletion of both ESYT1 and ESYT2 reduced store-operated Ca2+ entry (SOCE) and ORAI1-STIM1 clustering in Jurkat T cells. Further, depletion of E-Syts in primary T cells decreased Ca2+ entry and cytokine production. While the ER-PM junctions were reduced in both HeLa and Jurkat T cells deleted for ESYT1 and ESYT2, SOCE was impaired only in Jurkat T cells, suggesting that the membrane-tethering function of E-Syts is distinct from their role in SOCE. Mechanistically, E-Syt2S, the predominant isoform of E-Syt2 in T cells, recruited STIM1 to the junctions via a direct interaction. This study demonstrates a membrane-tethering-independent role of E-Syts in activation of CRAC channels in T cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Calcium Release Activated Calcium Channels / metabolism
  • Calcium Signaling*
  • Cells, Cultured
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Jurkat Cells
  • Neoplasm Proteins / metabolism*
  • ORAI1 Protein / metabolism
  • Protein Binding
  • Stromal Interaction Molecule 1 / metabolism*
  • Synaptotagmins / genetics
  • Synaptotagmins / metabolism*
  • T-Lymphocytes / metabolism*

Substances

  • Calcium Release Activated Calcium Channels
  • ESYT1 protein, human
  • ESYT2 protein, human
  • Neoplasm Proteins
  • ORAI1 Protein
  • ORAI1 protein, human
  • STIM1 protein, human
  • Stromal Interaction Molecule 1
  • Synaptotagmins