General autophagy-dependent and -independent lipophagic processes collaborate to regulate the overall level of lipophagy in yeast

ABSTRACT

Lipophagy in the yeast Saccharomyces cerevisiae is a microautophagic process in which lipid droplets (LDs) are directly engulfed into the vacuole, despite the fact that multiple core ATG (autophagy related) genes related to general autophagy have been reported to be essential for this process for unknown reasons. In this study, we report new findings about the regulation of lipophagy by analyzing, under different culture conditions, both the engulfment of LDs into the vacuole and the degradation of LD surface proteins. We find that the degradation of LD surface proteins relies on autophagy and can occur independently of lipophagy. Furthermore, glucose restriction can trigger an ATG1-independent lipophagic process, depending on the glucose concentration in the mediums. In summary, we describe an ATG-independent lipophagic process in yeast, such that the overall level of lipophagy in cells is governed by a dynamic balance between the ATG-dependent and -independent lipophagic processes.

Abbreviation

AP: autophagosome; ATG: autophagy related; CMA: chaperone-mediated autophagy; ESCRT: endosomal sorting complex required for transport; FA: fatty acid; LD: lipid droplet; Ld microdomains: liquid-disordered microdomains; NL: neutral lipid.

KEYWORDS:

• Autophagy
• autophagy related genes
• lipid droplet surface proteins
• lipid droplets
• lipophagy

Acknowledgements

A sincere thanks to Dr. Joel M. Goodman for his helpful discussion and suggestions for editing the paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15548627.2024.2325297

Additional information

Funding

This study was supported by the grants from the National Natural Science Foundation of China [31970051 and 32370047 to QG], and a grant from the Natural Science Foundation of Hunan Province, China [2020JJ4178 to QG].