Iron triggers TvPI4P5K proteostasis and Arf-mediated cell membrane trafficking to regulate PIP2 signaling crucial for multiple pathogenic activities of the parasitic protozoan Trichomonas vaginalis

Abstract

Trichomonas vaginalis is the etiologic agent of trichomoniasis, one of the most common non-viral sexually transmitted infections globally. Our previous work reported the role of phosphatidylinositol 4,5-bisphosphates (PIP2) signaling in the actin-dependent pathogenicity of T. vaginalis. This study further demonstrated that iron transiently regulated T. vaginalis phosphatidylinositol-4-phosphate 5-kinase (TvPI4P5K) proteostasis and its complex formation with an active ADP ribosylation factor TvArf220, facilitating co-trafficking to the plasma membrane, crucial for PIP2 production. In dominant-active HA-TvArf220 Q71L mutant, TvPI4P5K plasma membrane trafficking, PIP2 production, and intracellular calcium levels were increased, while these processes were inhibited in dominant-negative T31N mutant or those by Brefeldin A (BFA) treatment. Additionally, PIP2 replenishment reversed these inhibitions in the T31N mutant, suggesting the critical role of TvArf220 activation in PIP2-calcium signaling. Also, T31N mutant and BFA treatment impaired actin dynamics and cytoskeleton-dependent processes in T. vaginalis, further linking the role of TvArf220 to PIP2-calcium-dependent actin dynamics. Beyond cytoadherence, during host-parasite interactions, TvArf220 influenced both contact-dependent and -independent cytotoxicity, as well as phagocytotic capacity, contributing to the cytopathogenesis of human vaginal epithelial cells. Our findings underscore the key upstream regulation mechanisms of the PIP2 signaling, orchestrating the interplay between TvArf220-PIP2-calcium signaling and downstream actin cytoskeleton-driven pathogenicity in T. vaginalis.