title: DAP1, a negative regulator of autophagy, controls SubAB-mediated apoptosis and autophagy.
abstract: Autophagy and apoptosis play critical roles in cellular homeostasis and survival. Subtilase cytotoxin (SubAB), produced by non-O157 type Shiga-toxigenic Escherichia coli (STEC), is an important virulence factor in disease. SubAB, a protease, cleaves a specific site on the endoplasmic reticulum (ER) chaperone protein BiP/GRP78, leading to ER stress, and induces apoptosis. Here we report that in HeLa cells, activation of a PERK (RNA-dependent protein kinase [PKR]-like ER kinase)-eIF2α (α subunit of eukaryotic initiation factor 2)-dependent pathway by SubAB-mediated BiP cleavage negatively regulates autophagy and induces apoptosis through death-associated protein 1 (DAP1). We found that SubAB treatment decreased the amounts of autophagy markers LC3-II and p62 as well as those of mTOR (mammalian target of rapamycin) signaling proteins ULK1 and S6K. These proteins showed increased expression levels in PERK knockdown or DAP1 knockdown cells. In addition, depletion of DAP1 in HeLa cells dramatically inhibited the SubAB-stimulated apoptotic pathway: SubAB-induced Bax/Bak conformational changes, Bax/Bak oligomerization, cytochrome c release, activation of caspases, and poly(ADP-ribose) polymerase (PARP) cleavage. These results show that DAP1 is a key regulator, through PERK-eIF2α-dependent pathways, of the induction of apoptosis and reduction of autophagy by SubAB.
authors.affiliation: Department of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba, Japan yahirok@faculty.chiba-u.jp.
authors.forename: Kinnosuke
authors.initials: K
authors.lastname: Yahiro
authors.affiliation: Department of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Tsutsuki
authors.affiliation: Department of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Ogura
authors.affiliation: Department of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba, Japan Department of Legal Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Nagasawa
authors.affiliation: Cardiovascular and Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Joel
authors.initials: J
authors.lastname: Moss
authors.affiliation: Department of Molecular Infectiology, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Noda
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D001343:Autophagy / Q000502:physiology*; D000091342:Endoplasmic Reticulum Chaperone BiP; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000276:immunology*; D006367:HeLa Cells; D006801:Humans; D013381:Subtilisins / Q000235:genetics / Q000378:metabolism*; D050998:bcl-2 Homologous Antagonist-Killer Protein / Q000235:genetics / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; C494772:BAK1 protein, human; C494826:BAX protein, human; C091572:DAP protein, human; D000091342:Endoplasmic Reticulum Chaperone BiP; D029968:Escherichia coli Proteins; C000717247:HSPA5 protein, human; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D013381:Subtilisins; C527234:subtilase cytotoxin, E coli