title: Human Atg8-cardiolipin interactions in mitophagy: Specific properties of LC3B, GABARAPL2 and GABARAP.
abstract: The phospholipid cardiolipin (CL) has been proposed to play a role in selective mitochondrial autophagy, or mitophagy. CL externalization to the outer mitochondrial membrane would act as a signal for the human Atg8 ortholog subfamily, MAP1LC3 (LC3). The latter would mediate both mitochondrial recognition and autophagosome formation, ultimately leading to removal of damaged mitochondria. We have applied quantitative biophysical techniques to the study of CL interaction with various Atg8 human orthologs, namely LC3B, GABARAPL2 and GABARAP. We have found that LC3B interacts preferentially with CL over other di-anionic lipids, that CL-LC3B binding occurs with positive cooperativity, and that the CL-LC3B interaction relies only partially on electrostatic forces. CL-induced increased membrane fluidity appears also as an important factor helping LC3B to bind CL. The LC3B C terminus remains exposed to the hydrophilic environment after protein binding to CL-enriched membranes. In intact U87MG human glioblastoma cells rotenone-induced autophagy leads to LC3B translocation to mitochondria and subsequent delivery of mitochondria to lysosomes. We have also observed that GABARAP, but not GABARAPL2, interacts with CL in vitro. However neither GABARAP nor GABARAPL2 were translocated to mitochondria in rotenone-treated U87MG cells. Thus the various human Atg8 orthologs might play specific roles in different autophagic processes.
authors.affiliation: a Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular , Universidad del País Vasco , Bilbao , Spain.
authors.forename: Zuriñe
authors.initials: Z
authors.lastname: Antón
authors.affiliation: a Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular , Universidad del País Vasco , Bilbao , Spain.
authors.forename: Ane
authors.initials: A
authors.lastname: Landajuela
authors.affiliation: a Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular , Universidad del País Vasco , Bilbao , Spain.
authors.forename: Javier H
authors.initials: JH
authors.lastname: Hervás
authors.affiliation: a Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular , Universidad del País Vasco , Bilbao , Spain.
authors.forename: L Ruth
authors.initials: LR
authors.lastname: Montes
authors.affiliation: b Departamento de Bioquímica y Biología Molecular I , Universidad Complutense , Madrid , Spain.|c Instituto de Investigaciones Sanitarias San Carlos (IdISSC) , Madrid , Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: Hernández-Tiedra
authors.affiliation: b Departamento de Bioquímica y Biología Molecular I , Universidad Complutense , Madrid , Spain.|c Instituto de Investigaciones Sanitarias San Carlos (IdISSC) , Madrid , Spain.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Velasco
authors.affiliation: a Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular , Universidad del País Vasco , Bilbao , Spain.
authors.forename: Felix M
authors.initials: FM
authors.lastname: Goñi
authors.affiliation: a Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular , Universidad del País Vasco , Bilbao , Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Alonso
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000595:Amino Acid Sequence; D051017:Apoptosis Regulatory Proteins; D001343:Autophagy / Q000187:drug effects; D000071190:Autophagy-Related Protein 8 Family / Q000737:chemistry / Q000378:metabolism*; D002308:Cardiolipins / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D013759:Dronabinol / Q000494:pharmacology; D005909:Glioblastoma / Q000378:metabolism / Q000473:pathology; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D051336:Mitochondrial Membranes / Q000187:drug effects / Q000378:metabolism; D063306:Mitophagy / Q000187:drug effects; D011312:Pressure; D011485:Protein Binding / Q000187:drug effects; D012402:Rotenone / Q000494:pharmacology; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: C113757:ATG8 protein, S cerevisiae; D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D000071190:Autophagy-Related Protein 8 Family; D002308:Cardiolipins; C116741:GABARAP protein, human; C498698:GABARAPL2 protein, human; C502070:MAP1LC3B protein, human; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins; D012402:Rotenone; D013759:Dronabinol
keywords: CL; GABARAP; GABARAPL2; LC3B; glioblastoma; mitophagy