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Updated: Mar 17, 2026

Visualizing the Actin and Microtubule Cytoskeletons at the B-cell Immune Synapse Using Stimulated Emission Depletion STED Microscopy
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Calcium influx through CRAC channels controls actin organization and dynamics at the immune synapse

Catherine A Hartzell1,2, Katarzyna I Jankowska3,4, Janis K Burkhardt3,4

  • 1Immunology Program, Stanford University, Stanford, United States.

Elife
|July 22, 2016
PubMed

Insights

Calcium influx is essential for organizing actin dynamics at the immune synapse. This process regulates T cell receptor signaling intensity and duration by controlling actin polymerization and retrograde flow.

Area of Science:

  • Immunology
  • Cell Biology
  • Biochemistry

Background:

  • T cell receptor (TCR) engagement initiates calcium (Ca2+) influx via CRAC channels, forming an immune synapse.
  • Actin reorganization and retrograde flow at the synapse regulate TCR signaling duration and intensity.

Purpose of the Study:

  • To investigate the role of Ca2+ influx in regulating actin organization and dynamics at the immune synapse.
  • To elucidate the mechanisms by which Ca2+ influences actin polymerization, depolymerization, and retrograde flow.

Main Methods:

  • Live-cell imaging of actin dynamics and Ca2+ signaling at the immune synapse.
  • Perturbation of Ca2+ influx and analysis of downstream effects on actin.

Main Results:

  • Ca2+ influx is required for proper actin organization and dynamics at the immune synapse.
  • Calcium promotes actin depolymerization and directs WAVE2 localization to the lamellipod periphery.
  • Ca2+-dependent retrograde actin flow corrals ER tubules and STIM1/Orai1 complexes to the synapse center.

Conclusions:

  • Ca2+ acts as a critical regulator of actin organization and dynamics at the immune synapse.
  • This Ca2+-mediated regulation of actin may involve feedback loops modulating TCR signaling.

Keywords:
T lymphocyteactin dynamicscalciumcalcium release-activated calcium (CRAC) channelscell biologyendoplasmic reticulumhumanimmunological synapseimmunology

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