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J Cell Sci. 2014 Jul 15;127(Pt 14):3184-96. doi: 10.1242/jcs.153254. Epub 2014 May 16.

Tor and the Sin3-Rpd3 complex regulate expression of the mitophagy receptor protein Atg32 in yeast.

Author information

1
Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka 812-8582, Japan.
2
Laboratory of Biosignaling, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan.
3
Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka 812-8582, Japan Laboratory of Biosignaling, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan.
4
Department of Structural Pathology, Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, Niigata 951-8510, Japan.
5
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
6
Laboratory of Biosignaling, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan kanki@med.niigata-u.ac.jp.

Abstract

When mitophagy is induced in Saccharomyces cerevisiae, the mitochondrial outer membrane protein ScAtg32 interacts with the cytosolic adaptor protein ScAtg11. ScAtg11 then delivers the mitochondria to the pre-autophagosomal structure for autophagic degradation. Despite the importance of ScAtg32 for mitophagy, the expression and functional regulation of ScAtg32 are poorly understood. In this study, we identified and characterized the ScAtg32 homolog in Pichia pastoris (PpAtg32). Interestingly, we found that PpAtg32 was barely expressed before induction of mitophagy and was rapidly expressed after induction of mitophagy by starvation. Additionally, PpAtg32 was phosphorylated when mitophagy was induced. We found that PpAtg32 expression was suppressed by Tor and the downstream PpSin3-PpRpd3 complex. Inhibition of Tor by rapamycin induced PpAtg32 expression, but could neither phosphorylate PpAtg32 nor induce mitophagy. Based on these findings, we conclude that the Tor and PpSin3-PpRpd3 pathway regulates PpAtg32 expression, but not PpAtg32 phosphorylation.

KEYWORDS:

Atg32; Autophagy; Mitochondria; Mitophagy; Rpd3; Sin3; Tor; Yeast

PMID:
24838945
DOI:
10.1242/jcs.153254
[Indexed for MEDLINE]
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