ESCRT mediates micronucleophagy and macronucleophagy in yeast

Abstract

Endosomal sorting complex required for transport (ESCRT) is required for maintenance of nuclear functions and prevention of neurodegenerative diseases. The budding yeast Saccharomyces cerevisiae is an ideal model for studying ESCRT-dependent diseases. Nucleolar proteins are degraded by macronucleophagy and micronucleophagy after nutrient depletion and inactivation of target of rapamycin complex 1 (TORC1) kinase. Here, we show that ESCRT is critical for micronucleophagic degradation of nucleolar proteins upon TORC1 inactivation. In addition, ESCRT was also critical for rDNA condensation and nucleolar remodeling, which is necessary for proper micronucleophagic degradation of nucleolar proteins after TORC1 inactivation. On the other hand, ESCRT was dispensable for bulk macroautophagy, whereas it was also critical for macronucleophagy. Thus, ESCRT has an important role for elimination of nucleolar proteins in response to nutrient deprivation.

Keywords: Autophagy; ESCRT; Micronucleophagy; Nucleophagy; TORC1; macronucleophagy.