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Dr. Hassan Badrane is investigating opportunistic infections caused by Candida species of yeasts, particularly C. albicans. He is characterizing genes where expression has been found to be induced in vivo and their encoded protein have an immunogenic property. Presumably, these genes will be important during infection. Among them, he characterized IRS4 to encode for an Eps15 homology (EH) domain protein, which regulates the levels of phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P2). This regulation is exerted by activating lnp51p, a 5-phosphatase enzyme that converts PI(4,5)P2 to PI4P. Indeed, mutant strains in which either IRS4 or INP51 has been knocked-out, had higher levels of PI(4,5)P2, which in tum affected the cell wall integrity pathway and hyphal growth, and attenuated virulence to mice in a disseminated candidiasis model. In addition, these mutant strains exhibited abnormal intracellular patches of PI(4,5)P2 that colocalized with septins. Currently, he is deciphering the upstream regulation that controls the function of lrs4p/lnp51p as well as setpins.
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