The opportunistic pathogen Candida albicans is a common and mostly harmless inhabitant of the human gastrointestinal tract.However, the fungus can cause life-threatening blood stream infections in immunocompromised patients. The main entry site is believed to be the intestine, where the fungus can switch from its commensal state to a pathogenic state and translocate from the lumen into the blood stream. To date, the molecular mechanisms of this translocation are widely unknown. We discovered that the well known hyphae-associated gene ECE1 encodes a polypeptide, which seems to be processed into eight peptides via an unknown protease. One of the proposed peptides, Ece1-PIII, acts as a pore-forming toxin. To elucidate the role of Ece1-PIII in the translocation process, we created an ece1D deletion mutant, a revertant ece1D+ECE1 and a mutant that lacks only the PIII-encoding sequence. We used these strains and various synthetic versions of Ece1-PIII to assess its inﬂuence in all different processes that contribute to translocation. These include ﬁlamentation, adhesion, invasion, interepithelial dissemination, barrier function integrity (measurement of electrical resistance,TEER), damage and translocation itself. The latter was investigated with a modiﬁed established translocation assay and for all analyses we used differentiated Caco-2 intestinal cell monolayers. Our data show that Ece1 is dispensable for ﬁlamentation, adhesion and invasion, but is essential for epithelial damage of Caco-2 cells. The ability to impair the barrier function and the translocationpotential differ highly between different subclones of Caco-2 cells. We found that mutants lacking Ece1-PIII were not affected in translocation through monolayers of subclone HTB37, while Ece-PIII was essential for maximal translocation through the monolayers of sub-clone C2BBe1.
Foerster, T., Mogavero, S., Wilson, D., Mayer, F., Kasper, L., Allert, S., Hofs, S., Naglik, J., & Hube, B. (2015). The role of the pore-forming toxin Ece1 of Candida albicans during translocation through the intestinal epithelial barrier. Mycoses, 58, 66-67. https://doi.org/10.1111/myc.12362