PhD Studentship: An integrated light microscopy and structural biology approach to studying recepto

Platelets are blood cells that are vital in preventing bleeding when a blood vessel is damaged. Platelets sense vascular damage via proteins on their surface (receptors) which activate platelets, making them become ‘sticky’ and allowing them to plug the vessel to prevent blood loss. However, excessive or inappropriate activation of platelets can result in thrombosis (blood clots) which can cause heart attack or stroke, one of the biggest killers worldwide. Conversely, inefficient platelet activation can cause unregulated bleeding. Understanding how platelets become activated is therefore a major area of research.

This PhD studentship involves investigating the platelet receptor complex GPIb. This receptor is involved in the first step of platelet adhesion to a damaged vessel where loss of functional GPIb results in Bernard Soulier Syndrome (Othman and Emsley), a condition where patients suffer from severe clinical bleeding (e.g. nosebleeds and bruising). Through the GAPP project (Johnson et al) we have recently identified patients who exhibit mild bleeding and have novel variations in their GPIb gene sequence. This project aims to elucidate the mechanism by which these genetic variations cause bleeding, using a wide range of techniques established at the two hosting institutions. The successful candidate will spend time at both the Universities of Birmingham and Nottingham. In Birmingham the student will further scrutinise the established GAPP patient database to identify further patients with potential GPIb complex mutations and use advanced microscopy (e.g. single molecule localisation microscopy) and CRISPR/Cas9 genome editing to characterise the effect these genetic variations have on receptor location and clustering (Poulter et al., Khan et al). Effects on platelet activation will also be tested using standard assays such as platelet aggregation. In Nottingham, the student will carry out protein biochemistry to investigate the ability of the GPIb variants to bind to a range of GPIb ligands using assays such as surface plasmon resonance (Biacore) and isothermal titration calorimetry (ITC) (McEwan et al).

The project is one of six that has been funded through the Centre of Membrane Proteins and Receptors (COMPARE: http://www.birmingham-nottingham.ac.uk/compare/index.aspx) that focus on receptor clustering. The six studentships will form a doctoral training programme that will provide additional training and opportunities for collaboration.

Applications should be sent by 31 January.

Funding Notes

Funded by COMPARE, fees and stipend at UK rates for UK and EU nationals

References

• Johnson et al (2016) Whole exome sequencing identifies genetic variants in inherited thrombocytopenia with secondary qualitative function defects. Haematologica 101: 1170-79.
• Othman M, Emsley J. Gene of the issue: GP1BA gene mutations associated with bleeding. Platelets. 2017 Dec;28(8):832-836
• Poulter et al (2017) Clustering of glycoprotein VI (GPVI) dimers upon adhesion to collagen as a mechanism to regulate GPVI signaling in platelets. J Thromb Haemost., 5(3):549-564
• Khan et al (2017) CRISPR-Cas9 Mediated Labelling Allows for Single Molecule Imaging and Resolution. Sci Rep., 7(1):8450.
• McEwan et al (2011) Quaternary organization of GPIb-IX complex and insights into Bernard-Soulier syndrome revealed by the structures of GPIbβ and a GPIbβ/GPIX chimera. Blood 118(19):5292-301