Two-pore channel 2 (TPC2) modulates store-operated Ca(2+) entry.
Jośe López1, Natalia Dionisio, Alejandro Berna-Erro
1Department of Physiology (Cell Physiology Research Group), University of Extremadura, Cáceres, Spain.
Biochimica Et Biophysica Acta
|October 19, 2012
Summary
Two-pore channels (TPCs) regulate calcium (Ca2+) release and store-operated calcium entry (SOCE). This study reveals that TPC2 modulates SOCE by interacting with STIM1 and Orai1 in human cells.
Area of Science:
- Cellular Biology
- Ion Channel Physiology
- Calcium Signaling
Background:
- Two-pore channels (TPCs) are NAADP-sensitive channels mediating Ca2+ efflux from intracellular stores.
- Discharge of Ca2+ stores activates store-operated Ca2+ entry (SOCE).
- The specific role of TPCs in SOCE regulation was previously unknown.
Purpose of the Study:
- To investigate the role of TPCs, specifically TPC1 and TPC2, in the modulation of SOCE in human cells.
- To determine the interaction of TPCs with key SOCE components like STIM1 and Orai1.
Main Methods:
- Utilized gene silencing (siRNA) to reduce TPC2 expression in MEG01 and HEK293 cells.
- Measured thapsigargin (TG)- and thrombin-induced Ca2+ entry.
- Performed biotinylation assays to assess membrane localization of TPCs.
- Conducted co-immunoprecipitation experiments to identify protein interactions.
Main Results:
- Silencing TPC2 significantly attenuated TG- and thrombin-induced SOCE without affecting Ca2+ store loading.
- TPC1 and TPC2 were found to be localized in internal membranes.
- TPC2, but not TPC1, was shown to associate with STIM1 and Orai1 in Ca2+-depleted cells.
Conclusions:
- TPC2 plays a crucial role in modulating SOCE in human cells.
- The interaction between TPC2, STIM1, and Orai1 is a novel mechanism for SOCE regulation.
- This finding expands our understanding of calcium signaling pathways involving TPCs.
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