Doctor Simon Gras

Endocytosis, recycling, and plasma membrane dynamics of the apicomplexan parasite Toxoplasma gondii

Endocytosis processes are present in all organisms and are involved in a myriad of function such as motility, signalling, cell homeostasis etc… In apicomplexan parasites, endocytosis has mostly been studied for Plasmodium falciparum and very few information is available for Toxoplasma. One of the critical pitfalls for the study of endocytosis is the absence of reliable endocytosis assays. Using antibodies, we are able to demonstrate the presence of endocytic events (Gras S et al. PLOS Biology 2019). Now using a dual labelling strategy, we developed a new assay opening the road to the analysis of endocytosis in Toxoplasma gondii.

Research Focus:

• Identification of endocytosed and recycled proteins
• Identification and characterisation of proteins involved in endocytic mechanisms
• Analysis of plasma membrane endocytosis and potential recycling in intracellular parasite
• Exploiting the endocytic machinery for novel treatment strategies against Toxoplasma
  
  

Project origin: While adapting the bead translocation assay in Toxoplasma (Whitelaw JA et al. BMC Biology, 2017), I observed beads translocation independently of motility. This observation suggested that the plasma membrane could be quite dynamic, and that trail formation was not the only way to get rid of the translocated material. Although SAG1 has been usually used as a simple plasma membrane marker, the fate during gliding and replication of this surface protein, and by extension of the plasma membrane, has not been really studied to date. Starting from this point and after two years of work (Gras S et al. PLOS Biology 2019), we obtained enough data to show that endocytosis was happening in Toxoplasma using SAG1 antibodies. Now I aiming to improve this detection methods and go further in the characterisation of the plasma membrane dynamics (endocytosis, recycling, and secretion).