title: Kibra and aPKC regulate starvation-induced autophagy in Drosophila.
abstract: Autophagy is a bulk degradation system that functions in response to cellular stresses such as metabolic stress, endoplasmic reticulum stress, oxidative stress, and developmental processes. During autophagy, cytoplasmic components are captured in double-membrane vesicles called autophagosomes. The autophagosome fuses with the lysosome, producing a vacuole known as an autolysosome. The cellular components are degraded by lysosomal proteases and recycled. Autophagy is important for maintaining cellular homeostasis, and the process is evolutionarily conserved. Kibra is an upstream regulator of the hippo signaling pathway, which controls organ size by affecting cell growth, proliferation, and apoptosis. Kibra is mainly localized in the apical membrane domain of epithelial cells and acts as a scaffold protein. We found that Kibra is required for autophagy to function properly. The absence of Kibra caused defects in the formation of autophagic vesicles and autophagic degradation. We also found that the well-known cell polarity protein aPKC interacts with Kibra, and its activity affects autophagy upstream of Kibra. Constitutively active aPKC decreased autophagic vesicle formation and autophagic degradation. We confirmed the interaction between aPKC and Kibra in S2 cells and Drosophila larva. Taken together, our data suggest that Kibra and aPKC are essential for regulating starvation-induced autophagy.
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Ahrum
authors.initials: A
authors.lastname: Jin
authors.affiliation: Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Neufeld
authors.affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea. Electronic address: jchoe@kaist.ac.kr.
authors.forename: Joonho
authors.initials: J
authors.lastname: Choe
mesh_terms: D000818:Animals; D001343:Autophagy; D002460:Cell Line; D016764:Cell Polarity; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000378:metabolism*; D060066:Protein Interaction Maps; D011493:Protein Kinase C / Q000378:metabolism*; D013217:Starvation / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D025521:Tumor Suppressor Proteins; C548168:kibra protein, Drosophila; C115015:PKC-3 protein; D011493:Protein Kinase C
keywords: Atg8a; Autophagy; Kibra; Starvation; aPKC