About the Project
Neutrophils are innate immune cells that combat bacterial and fungal infections and help in wound healing. These immune functions of neutrophils are orchestrated using highly specialized responses. The cells can phagocytose pathogens and debris, extrude their DNA to entrap pathogens, and produce reactive oxygen species (ROS) and secrete lytic enzymes that kill pathogens, as well as producing inflammatory mediators to attract other immune cells. Several of these neutrophil responses are mediated by the guanine-nucleotide exchange factor (GEF) P-Rex1. In vivo, P-Rex1 contributes to the recruitment of neutrophils to sites of infection and to the clearing of bacterial infections (1-4).
These immune P-Rex1 functions are assumed to be mediated through its catalytic GEF activity, which activates the Small GTPase Rac, a key regulator of cytoskeletal dynamics and ROS production. However, we have unpublished data suggesting that P-Rex1 also has important adaptor functions, independent of GEF activity.
This PhD project aims to elucidate the importance of P-Rex1 adaptor functions for neutrophil biology. To this end, we have generated a mouse strain named Prex1* in which the GEF is mutated to be catalytically inactive. We hypothesize that Prex1* neutrophils will have dampened signaling pathways, receptor trafficking and effector responses, and that Prex1* mice will have reduced immunity to bacterial infections.
The PhD student will isolate neutrophils from wild-type, Prex1-deficient and Prex1* mice to evaluate principal neutrophil responses, including phagocytosis, degranulation, ROS, NET and cytokine production, adhesion, and migration. S/he will also measure major neutrophil signaling pathways and receptor trafficking. S/he will employ various techniques such as ROS and enzyme activity assays, imaging, western blotting, ELISA and flow cytometry. In vivo, s/he will assess neutrophil recruitment to inflamed and infected organs and measure the capacity to kill bacteria, using methods such as tissue lavages, histology and bacterial culture. S/he will become an expert in signaling mechanisms, vesicle and receptor trafficking and phagocyte biology. Moreover, the findings from this PhD may have significant impact on the development of future treatment strategies in inflammatory diseases exacerbated by excessive neutrophil recruitment and responses.
The student will join a friendly lab within the Signalling Programme at the Babraham Institute and be part of our vibrant PhD student community (currently ~50 students). Our Graduate Programme is recognised as a model of best practice, promoting in-depth knowledge, critical thinking, clear communication of scientific results and learning of transferable skills. The student will be registered at Cambridge University, which awards the PhD degree, and be a member of a Cambridge college, which offer an intellectually stimulating environment and excellent networking events.
References
1) Pantarelli C, Welch HC (2018) Rac-GTPases and Rac-GEFs in neutrophil adhesion, migration and recruitment. Eur J Clin Invest, e12939.
2) Welch HC (2015) Regulation and Function of P-Rex Family Rac-GEFs. Review. Small GTPases 6, 49-70.
3) Welch HC et al (2005) P-Rex1 regulates neutrophil function. Curr Biol 15, 1867-1873.