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Endogenously expressed Trp1 is involved in store-mediated Ca2+ entry by conformational coupling in human platelets
Juan A Rosado1, Sharon L Brownlow, Stewart O Sage
1Department of Physiology, University of Cambridge, United Kingdom.
The Journal of Biological Chemistry
|August 28, 2002
Summary
Human TRP1 channels interact with IP3 receptors to control calcium entry in platelets. This interaction is crucial for store-operated calcium influx, a key process in cell signaling.
Area of Science:
- Cell Biology
- Ion Channel Physiology
Background:
- Physical interactions between transient receptor potential (Trp) channels and inositol 1,4,5-trisphosphate receptors (IP(3)Rs) are proposed mechanisms for store-mediated calcium entry.
- The human homologue of Drosophila TRP channel, hTrp1, is investigated for its role in store-mediated calcium influx.
Purpose of the Study:
- To examine the role of hTrp1 in store-mediated calcium entry in human platelets.
- To investigate the coupling between hTrp1 and IP(3)R type II during platelet activation.
Main Methods:
- Utilized a specific antibody against hTrp1 to inhibit calcium and manganese entry.
- Stimulated human platelets with thrombin to study receptor coupling.
- Employed inhibitors of IP(3) recycling and IP(3)Rs, and jasplakinolide to stabilize actin filaments.
Main Results:
- An anti-hTrp1 antibody inhibited store depletion-induced Ca(2+) and Mn(2+) entry in a dose-dependent manner.
- Thrombin stimulation led to coupling between IP(3) receptor type II and hTrp1, which was reversible by store refilling.
- Inhibition of IP(3) recycling, IP(3)Rs, or actin stabilization abolished thrombin-induced coupling.
Conclusions:
- hTrp1 is involved in activating store-mediated calcium entry by coupling with IP(3)R type II in human platelets.
- This interaction is essential for thrombin-evoked calcium influx, independent of intracellular calcium release.