Inhibitor of growth protein 4 interacts with Beclin 1 and represses autophagy

// Valentina Sica 1,2,3,4,5,* , José Manuel Bravo-San Pedro 1,2,3,4,5,* , Guo Chen 1,2,3,4,5 , Guillermo Mariño 3,6 , Sylvie Lachkar 1,2,3,4,5 , Valentina Izzo 1,2,3,4,5 , Maria Chiara Maiuri 1,2,3,4,5 , Mireia Niso-Santano 3,7,8,** and Guido Kroemer 1,2,3,4,5,9,10,** 1 Université Paris Descartes, Sorbonne Paris Cité, Paris, France 2 Equipe 11 labellisée Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, Paris, France 3 Institut National de la Santé et de la Recherche Médicale, Paris, France 4 Université Pierre et Marie Curie, Paris, France 5 Metabolomics and Cell Biology Platforms, Gustave Roussy Cancer Campus, Villejuif, France 6 Departamento de Biología Fundamental, Instituto de Investigación Sanitaria del Principado de Asturias, Universidad de Oviedo, Spain 7 Centro de Investigación Biomédica en Red en Enfermedades Neurodegenerativas, Cáceres, Spain 8 Facultad de Enfermería y Terapia Ocupacional, Universidad de Extremadura, C.P, Cáceres, Cáceres, Spain 9 Pôle de Biologie, Hôpital Européen Georges Pompidou, AP-HP, Paris, France 10 Department of Women's and Children's Health, Karolinska University Hospital, Stockholm, Sweden * These authors have contributed equally to this article ** These authors share co-senior authorship Correspondence to: Guido Kroemer, email: // Keywords : cancer, ING4, PIK3C3, TP53, Autophagy Received : March 16, 2017 Accepted : April 17, 2017 Published : July 06, 2017 Abstract Beclin 1 (BECN1) is a multifunctional protein that activates the pro-autophagic class III phosphatidylinositol 3-kinase (PIK3C3, best known as VPS34), yet also interacts with multiple negative regulators. Here we report that BECN1 interacts with inhibitor of growth family member 4 (ING4), a tumor suppressor protein that is best known for its capacity to interact with the tumor suppressor protein p53 (TP53) and the acetyltransferase E1A binding protein p300 (EP300). Removal of TP53 or EP300 did not affect the BECN1/ING4 interaction, which however was lost upon culture of cells in autophagy-inducing, nutrient free conditions. Depletion of ING4 stimulated the enzymatic activity of PIK3C3, as visualized by means of a red fluorescent protein-tagged short peptide (FYVE) that specifically binds to phosphatidylinositol-3-phosphate (PI3P)-containing subcellular vesicles and enhanced autophagy, as indicated by an enhanced lipidation of microtubule-associated proteins 1A/1B light chain 3 beta (LC3B) and the redistribution of a green-fluorescent protein (GFP)-LC3B fusion protein to cytoplasmic puncta. The generation of GFP-LC3B puncta stimulated by ING4 depletion was reduced by simultaneous depletion, or pharmacological inhibition, of PIK3C3/VPS34. In conclusion, ING4 acts as a negative regulator of the lipid kinase activity of the BECN1 complex, and starvation-induced autophagy is accompanied by the dissociation of the ING4/BECN1 interaction.