Identification of novel Rac-GEF functions
Lead Research Organisation:
University of Cambridge
Department Name: School of Biological Sciences
Abstract
The overall aim of this Ph.D. project is to identify novel functions of Rac-GEFs through the use of new reporter and knock-in mouse strains generated in the lab. The particular aims of this project are three-part.
Firstly, I aim to characterise cytoskeletal dynamics controlled by the Rac-GEF Tiam1 during neutrophil adhesion, using unpublished Tiam1-deficient mouse strains generated in the lab that express a reporter for F-actin structures. This project is based on previous work in the lab by Kirsti Hornigold and Martin Baker, which identified adhesion-dependent defects in Tiam1-deficient neutrophils, leading us to hypothesise that the internal F-actin dynamics and focal adhesion structures may be affected in Tiam1-/- neutrophils.
My second aim is to investigate our hypothesis that different types of neutrophil Rac-GEFs control distinct aspects of adhesion and migration. I will attempt to define which Rac-GEFs generate the complex spatiotemporal patterns of Rac activity that govern neutrophil adhesion, spreading, polarisation and migration. This will be done using FRET imaging of primary isolated neutrophils from unpublished Rac-activity FRET reporter mouse strains generated in the lab that are deficient in the principal neutrophil Rac-GEFs Prex1, Vav1, Tiam1 or DOCK2.
The final aim of my Ph.D. project is to define the adaptor functions of Prex Rac-GEFs in glucose homeostasis. Preliminary data from Elpida Tsonou, a previous Ph.D. student in the lab, show that Prex-deficient mice have altered fasting blood glucose levels, glucose tolerance and insulin sensitivity. Dr Tsonou has since generated a Prex2E22AN204A mouse strain, in which two point mutations have abolished Prex2 Rac-GEF activity. She has also begun to generate an equivalent Prex1 GEF-dead mouse strain. My aim is to use these novel mouse strains to elucidate the importance of the catalytic Rac-GEF activity of Prex1 and Prex2 for glucose homeostasis, as well as attempting to elucidate some of the underlying cellular mechanisms.
Firstly, I aim to characterise cytoskeletal dynamics controlled by the Rac-GEF Tiam1 during neutrophil adhesion, using unpublished Tiam1-deficient mouse strains generated in the lab that express a reporter for F-actin structures. This project is based on previous work in the lab by Kirsti Hornigold and Martin Baker, which identified adhesion-dependent defects in Tiam1-deficient neutrophils, leading us to hypothesise that the internal F-actin dynamics and focal adhesion structures may be affected in Tiam1-/- neutrophils.
My second aim is to investigate our hypothesis that different types of neutrophil Rac-GEFs control distinct aspects of adhesion and migration. I will attempt to define which Rac-GEFs generate the complex spatiotemporal patterns of Rac activity that govern neutrophil adhesion, spreading, polarisation and migration. This will be done using FRET imaging of primary isolated neutrophils from unpublished Rac-activity FRET reporter mouse strains generated in the lab that are deficient in the principal neutrophil Rac-GEFs Prex1, Vav1, Tiam1 or DOCK2.
The final aim of my Ph.D. project is to define the adaptor functions of Prex Rac-GEFs in glucose homeostasis. Preliminary data from Elpida Tsonou, a previous Ph.D. student in the lab, show that Prex-deficient mice have altered fasting blood glucose levels, glucose tolerance and insulin sensitivity. Dr Tsonou has since generated a Prex2E22AN204A mouse strain, in which two point mutations have abolished Prex2 Rac-GEF activity. She has also begun to generate an equivalent Prex1 GEF-dead mouse strain. My aim is to use these novel mouse strains to elucidate the importance of the catalytic Rac-GEF activity of Prex1 and Prex2 for glucose homeostasis, as well as attempting to elucidate some of the underlying cellular mechanisms.
