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STIM1 is required for attenuation of PMCA-mediated Ca2+ clearance during T-cell activation
Michael F Ritchie1, Elsie Samakai, Jonathan Soboloff
1Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140, USA.
Abstract:
T-cell activation involves a complex signalling cascade uniquely dependent on elevated cytosolic Ca(2+) levels. Further, the spatiotemporal characteristics of this Ca(2+) signal play a critical role in this process via selective activation of transcription factors. In T cells, store-operated Ca(2+) entry (SOCe) is the primary Ca(2+) influx pathway; however, cytosolic Ca(2+) concentration depends upon the balance between Ca(2+) influx and extrusion. The plasma membrane Ca(2+) ATPase (PMCA) has previously been identified as a critical player in Ca(2+) clearance in T cells. Here, we provide data revealing both functional and physical links between the activation of stromal interacting molecule 1 (STIM1) and PMCA-mediated Ca(2+) clearance. Due to the ubiquitous expression of both STIM1 and PMCA, these findings have wide-ranging implications for Ca(2+) signalling in multiple cell types.
Insights
Stromal interacting molecule 1 (STIM1) activation links to plasma membrane Ca(2+) ATPase (PMCA) in T-cell calcium signaling. This discovery impacts understanding of calcium clearance and T-cell activation across many cell types.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- T-cell activation relies on calcium (Ca2+) signaling, with specific spatiotemporal patterns regulating transcription factors.
- Store-operated Ca2+ entry (SOCe) is the main Ca2+ influx pathway in T cells, but cytosolic Ca2+ levels are determined by influx and extrusion.
- Plasma membrane Ca2+ ATPase (PMCA) is crucial for Ca2+ clearance in T cells.
Purpose of the Study:
- To investigate the functional and physical relationship between STIM1 activation and PMCA-mediated Ca2+ clearance in T cells.
- To elucidate the role of STIM1-PMCA interaction in regulating cytosolic Ca2+ homeostasis during T-cell activation.
Main Methods:
- Utilized techniques to assess functional links between STIM1 activation and PMCA activity.
- Employed methods to demonstrate physical interactions between STIM1 and PMCA.
- Investigated Ca2+ signaling dynamics in T cells.
Main Results:
- Demonstrated a functional link between STIM1 activation and PMCA-mediated Ca2+ extrusion.
- Provided evidence for a physical association between STIM1 and PMCA.
- Showcased the importance of this interaction in controlling Ca2+ homeostasis.
Conclusions:
- STIM1 activation is functionally and physically coupled to PMCA-mediated Ca2+ clearance in T cells.
- These findings highlight a novel regulatory mechanism for Ca2+ signaling in T cells.
- The ubiquitous expression of STIM1 and PMCA suggests broad implications for Ca2+ signaling in various cell types.
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