Monitoring of Iron Depletion-Induced Mitophagy in Pathogenic Yeast

Abstract

Mitophagy, which is the degradation of mitochondria via selective autophagic machinery, is thought to be involved in regulating the mass and function of mitochondria. Methods for detection of mitophagy have been reported for several fungal cells including some budding yeast, methylotrophic yeast, and filamentous fungi. Mitophagy in Saccharomyces cerevisiae is activated under nitrogen-poor conditions; however, the regulatory mechanism of mitophagy in most fungi has not been elucidated. Here we describe methods to monitor mitophagy in the pathogenic yeast Candida glabrata under iron-depleted conditions but not under nitrogen starvation. This observation may provide some clues to elucidate the physiological roles of mitophagy in eukaryotes.

Selective Degradation of Mitochondria by Mitophagy in Pathogenic Fungi

“…Since the first evidence of mitophagy in yeast was reported by Kissova et al [34], a considerable amount of work has been conducted in mitophagy. Methods for detecting mitophagy in fungi include transmission electron microscopy (TEM), fluorescence microscopy for co-localization of mitochondria with autophagosomes, and western blotting to quantify degradation of mitochondrial proteins [35] [36] [37]. TEM is a widely used methodology to detect mitophagy [36].…”

“…This assay is more appropriate and specific for mitophagy [42]. However, high levels of mitophagy may be required to detect mitochondrial protein degradation, and changes in protein levels can be seriously affected by other factors, for example, by proteasomal degradation pathways and alterations in biogenesis [37]. The outer mitochondrial membrane proteins are degraded by both autophagy and the proteasome, which makes interpretation of data from Western blot assays very complicated [43].…”