Essential roles of phosphatidylinositol 4-phosphate phosphatases Sac1p and Sjl3p in yeast autophagosome formation

Increased Phospholipid Flux Bypasses Overlapping Essential Requirements for the Yeast Sac1p Phosphoinositide Phosphatase and ER-PM Membrane Contact Sites

“…These differences suggest that phosphoinositide defects trigger an autophagy response, as opposed to being caused by membrane effects resulting from ER-PM tether deletion. Previous reports showed that autophagosome fusion with the vacuole is dependent on SAC1 and other related phosphoinositide phosphate phosphatases ( 91 , 100 ). However, to our knowledge, these results are the first to show a phosphoinositide-dependent control of autophagy gene expression.…”

Phagophore closure, autophagosome maturation and autophagosome fusion during macroautophagy in the yeast Saccharomyces cerevisiae

“…More recently, it has been shown in yeast, C. elegans, and mammals that dephosphorylation of phosphatidylinositol-4-phosphate (PtdIns4P) into PtdIns by Sac1 is also important for the fusion of autophagosomes with vacuoles/lysosomes [51][52][53][54] (Fig. 3).…”

“…3). In the absence of this phosphatase, high levels of PtdIns4P on autophagosomes impede the recruitment of SNAREs, impairing autophagosome fusion with vacuoles [52,53] (Fig. 3).…”

“…3). PtdIns4P is transported from the Golgi to the PAS by Atg9-positive vesicles when it is accumulated at the Golgi upon Sac1 inactivation [52,53,55]. However, it is unclear whether in wild-type cells PtdIns4P dephosphorylation is important for autophagosome fusion with vacuoles and also plays a role in Atg machinery release.…”