title: ATG14 facilitated lipophagy in cancer cells induce ER stress mediated mitoptosis through a ROS dependent pathway.
abstract: Understanding the dynamics of autophagy and apoptosis crosstalk in cancer progression remains a challenging task. Here, we reported how the autophagy protein ATG14 induces lipophagy-mediated mitochondrial apoptosis. The overexpression of ATG14 in HeLa cells inhibited cell viability and increased mitochondrial apoptosis and endoplasmic reticulum (ER) stress. Furthermore, inhibition of this ATG14-induced autophagy promoted apoptosis. ATG14 overexpression resulted in the accumulation of free fatty acids (FFA), with a concomitant decrease in the number of lipid droplets. Our data showed that ER stress induced by ATG14 was due to the lipophagy-mediated FFA accumulation, which resulted in ROS-dependent mitochondrial stress leading to apoptosis. Inhibition of lipophagy in HeLa-ATG14 cells enhanced the cellular viability and rescued them from lipotoxicity. Mechanistically, we found that ATG14 interacted with Ulk1 and LC3, and knock down of Ulk1 prevented the lipidation of LC3 and autophagy in HeLa-ATG14 cells. We also identified a phosphatidylethanolamine (PE) binding region in ATG14, and the addition of Ulk1 to Hela-ATG14 cells decreased the ATG14-PE interaction. Lastly, confocal microscopy studies showed that the decrease in ATG14-PE binding was concomitant with the increase in LC3 lipidation over time, confirming the importance of Ulk1 to sort PE to LC3 during ATG14 mediated lipophagy induction. In conclusion, ATG14 and Ulk1 interact to induce lipophagy resulting in FFA accumulation leading to ER stress-mediated apoptosis.
authors.affiliation: Department of Life Science, National Institute of Technology, Rourkela 769008, Odisha, India.
authors.forename: Subhadip
authors.initials: S
authors.lastname: Mukhopadhyay
authors.affiliation: Division of Medical Oncology, University of Colorado School of Medicine, United States.
authors.forename: Isabel R
authors.initials: IR
authors.lastname: Schlaepfer
authors.affiliation: Division of Endocrinology Metabolism and Diabetes, University of Colorado School of Medicine, United States.
authors.forename: Bryan C
authors.initials: BC
authors.lastname: Bergman
authors.affiliation: Department of Life Science, National Institute of Technology, Rourkela 769008, Odisha, India.
authors.forename: Prashanta Kumar
authors.initials: PK
authors.lastname: Panda
authors.affiliation: Department of Life Science, National Institute of Technology, Rourkela 769008, Odisha, India.
authors.forename: Prakash Priyadarshi
authors.initials: PP
authors.lastname: Praharaj
authors.affiliation: Department of Life Science, National Institute of Technology, Rourkela 769008, Odisha, India.
authors.forename: Prajna Paramita
authors.initials: PP
authors.lastname: Naik
authors.affiliation: Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, Colorado University of Colorado Cancer Center, University of Colorado Denver, Aurora, CO, United States.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Agarwal
authors.affiliation: Department of Life Science, National Institute of Technology, Rourkela 769008, Odisha, India. Electronic address: sbhutia@nitrkl.ac.in.
authors.forename: Sujit Kumar
authors.initials: SK
authors.lastname: Bhutia
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics* / Q000378:metabolism; D017209:Apoptosis / Q000235:genetics; D001343:Autophagy / Q000235:genetics; D000071189:Autophagy-Related Protein-1 Homolog / Q000235:genetics* / Q000378:metabolism; D000071183:Autophagy-Related Proteins / Q000235:genetics* / Q000378:metabolism; D059865:Endoplasmic Reticulum Stress / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000235:genetics* / Q000378:metabolism; D008928:Mitochondria / Q000235:genetics / Q000473:pathology; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D010714:Phosphatidylethanolamines / Q000378:metabolism; D011485:Protein Binding; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: C539000:ATG14 protein, human; D033942:Adaptor Proteins, Vesicular Transport; D000071183:Autophagy-Related Proteins; D047908:Intracellular Signaling Peptides and Proteins; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D010714:Phosphatidylethanolamines; D017382:Reactive Oxygen Species; C483858:phosphatidylethanolamine; D000071189:Autophagy-Related Protein-1 Homolog; C484754:ULK1 protein, human
keywords: ATG14; Apoptosis; ER stress; Lipophagy; Reactive oxygen species; Ulk1