Studies of calcium signalling mechanisms in human platelets

Platelet activation is essential in haemostasis and thrombosis and central to this role is cytosolic calcium (Ca2+) elevation. The two ways in which this can occur are release from intracellular Ca2+ stores and the entry of Ca2+ across the plasma membrane (PM). Changes in cytosolic Ca2+ are required to enable a variety of platelet responses. In platelets and other non-excitable cells, the major route of Ca2+ entry occurs as a result of Ca2+ depletion from intracellular stores, and is known as store operated Ca2+ entry (SOCE). STIM1 is the Ca2+ sensing protein of the endoplasmic reticulum (ER) which activates Orai channels in the plasma membrane allowing Ca + entry. However, not all of the details of Ca2+ entry are understood. In platelets, two other pathways also enable Ca2+ entry. The P2X1 receptor is a ligand gated ion channel activated by the binding of ATP. Second messengers (such as 1,2-diacyl-sn- glycerol [DAG]) and phosphatidylinositol-3,4,5-trisphosphate (PI-3,4,5-P3) may directly gate plasma membrane cation channels such as the transient receptor potential canonical 6 (TRPC6) channel. -- The main aim of this study was to examine the role of STIM1 and TRPC proteins in Ca2+ entry in human platelets. The TRPC1 protein was originally proposed to be a major component of the SOC channel based on the observation that a commercial preparation of an anti-TRPCl antibody against the channel impaired SOCE in platelets. However, in the current study I demonstrate the failure of this reagent to bind to TRPC1. The previously reported inhibitory effect on SOCE may be due in part to be a result of the azide component of the antibody preparation.

Name dc:type.qualificationname

Doctor of Philosophy

Level dc:type.qualificationlevel

Doctoral Thesis

Grantor dc:publisher.institution

King's College London

Year dc:date.issued

2012

Author dc:creator

• Ambily, Anju

Advisors dc:contributor.advisor

• Authi, Kalwant Singh
• Pearson, Jeremy David

Language dc:language

eng

Identifier

oai:kclpure.kcl.ac.uk:studenttheses/0754e26d-374a-485e-9387-41e074926048

OAI identifier oai:identifier

oai:kclpure.kcl.ac.uk:studenttheses/0754e26d-374a-485e-9387-41e074926048