Role of Apolipoproteins L in immunity and disease (APOLs)
Role of Apolipoproteins L in immunity and disease
Start date: Sep 1, 2015,
End date: Aug 31, 2020
Work conducted in my laboratory on the trypanosome killing factor of human serum led to the identification of the primate-specific Apolipoprotein L1 (APOL1) as a novel pore-forming protein with striking similarities with proteins of the apoptotic BCL2 family. APOL1 belongs to a family of proteins induced under inflammatory conditions in myeloid and endothelial cells. APOL1 is efficiently neutralized by the SRA protein of Trypanosoma rhodesiense, accounting for the ability of this trypanosome subspecies to infect humans and cause sleeping sickness. We found that natural APOL1 variants escaping SRA neutralization and therefore conferring human resistance to T. rhodesiense are associated with chronic kidney disease.Moreover, transgenic mice expressing these APOL1 variants exhibit an obese phenotype. Our unpublished results also indicate that APOLs control the lifespan of dendritic cells and podocytes activated by viral stimuli. Therefore, we propose that the pathology of APOL variants is due to their deregulated activity on the control of the cellular lifespan in myeloid/endothelial cells activated by pathogen detection.This project aims at characterizing (i) the molecular mechanism by which APOLs control the lifespan of activated dendritic cells and podocytes, which has direct impact on innate immunity and inflammation, and (ii) the mechanism by which APOL1 variants cause pathology. In addition, we plan to detail the physiological function of APOLs by studying the phenotype of transgenic mice either expressing human APOL1 (wild-type and variants) or devoid of APOL genes, which we have recently generated. Finally, we propose to exploit the extraordinary potential of trypanosomes for antigenic variation in order to produce SRA variants able to neutralize the pathogenic APOL1 variants. Preliminary experiments suggest that in podocytes SRA antagonizes APOL1 induction by viral stimulus and subsequent cell death, opening new perspectives to treat kidney disease.
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