MSS2-mediated ROS and calcium are essential for Candida albicans invasive behavior and virulence

Mitochondrial function is essential for virulence in Candida albicans, yet the mechanism by which mitochondria influence invasive behavior remains largely undefined. Here, we uncover a novel, mitochondria-centered mechanism in which the mitochondrial-associated gene MSS2 controls invasive growth through the regulation of calcium–ROS homeostasis. Deletion of MSS2 exhibits impaired invasive growth on solid agar without affecting hyphal formation in liquid, suggesting a unique contact-specific regulatory program. Indeed, we found that the regulation of these processes by Mss2 is linked to the regulation of cytosolic calcium levels and cellular ROS production. Furthermore, transcriptomic profiling identified the MSS2-regulated genes, UME6, SAC1, RIM8, and ORF19.1841, whose expression is dependent on calcium and ROS levels. Restoration of invasive phenotypes through exogenous ROS confirms the functional significance of this calcium-ROS circuit. In systemic infection models., mutants lacking MSS2 or its downstream genes exhibit severe host cell invasion and virulence defects. Together, this work is the first to reveal that mitochondrial regulation of a coordinated calcium-ROS circuit is indispensable for invasive hyphal growth in C. albicans. These findings further refine the current model of fungal invasive progression and may provide useful information for future studies aiming to target mitochondrial signaling in pathogenic fungi. Overall design: Total mRNA extracted from wild-type (WT) and mss2? strains in RPMI 1640 liquid medium or on RPMI 1640 agar plate for 24 hours at 30°C was analyzed using RNA sequencing.