Journal Article

Ambra1 regulates autophagy and development of the nervous system

Fuoco, Claudia, Piacentini, Mauro, Chowdhury, Kamal, Giunta, Luigi, Schwartz, Peter, Stoykova, Anastassia, Nardacci, Roberta, Romagnoli, Alessandra, Gruss, Peter, Corazzari, Marco, Maria Fimia, Gian, Ucar, Ahmet, Di Bartolomeo, Sabrina, Cecconi, Francesco

2007

Overview

The identification of the large protein Ambra-1, which regulates autophagy and plays a crucial role in embryogenesis is described. The absence of Ambra-1 function during development results in severe neural tube defects associated with autophagy impairment, accumulation of ubiquitinated proteins, unbalanced cell proliferation and excessive apoptotic cell death. Autophagy is a self-degradative process involved both in basal turnover of cellular components and in response to nutrient starvation or organelle damage in a wide range of eukaryotes 1 , 2 , 3 . During autophagy, portions of the cytoplasm are sequestered by double-membraned vesicles called autophagosomes, and are degraded after fusion with lysosomes for subsequent recycling 4 . In vertebrates, this process acts as a pro-survival or pro-death mechanism in different physiological and pathological conditions, such as neurodegeneration and cancer 2 , 5 , 6 , 7 ; however, the roles of autophagy during embryonic development are still largely uncharacterized 3 . Beclin1 (Becn1; coiled-coil, myosin-like BCL2-interacting protein) is a principal regulator in autophagosome formation, and its deficiency results in early embryonic lethality 8 , 9 . Here we show that Ambra1 (activating molecule in Beclin1-regulated autophagy), a large, previously unknown protein bearing a WD40 domain at its amino terminus, regulates autophagy and has a crucial role in embryogenesis. We found that Ambra1 is a positive regulator of the Becn1-dependent programme of autophagy, as revealed by its overexpression and by RNA interference experiments in vitro . Notably, Ambra1 functional deficiency in mouse embryos leads to severe neural tube defects associated with autophagy impairment, accumulation of ubiquitinated proteins, unbalanced cell proliferation and excessive apoptotic cell death. In addition to identifying a new and essential element regulating the autophagy programme, our results provide in vivo evidence supporting the existence of a complex interplay between autophagy, cell growth and cell death required for neural development in mammals.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: Adaptor Proteins, Signal Transducing / Animals / Apoptosis / Apoptosis Regulatory Proteins / Autophagy - genetics / Autophagy - physiology / Beclin-1 / Cell death / Cell Line / Cells / Cellular / Embryo, Mammalian - cytology / Embryo, Mammalian - metabolism / Embryonic Development - genetics / Embryonic Development - physiology / Embryonic growth stage / Embryonic Stem Cells / Embryos / Eukaryotes / Female / Humanities and Social Sciences / Impairment / letter / Male / Mammals / Mice / Mice, Inbred C57BL / Microtubule-Associated Proteins - genetics / Microtubule-Associated Proteins - metabolism / Molecular Sequence Data / Molecules / Mortality / multidisciplinary / Mutation - genetics / Nervous system / Nervous System - cytology / Nervous System - embryology / Nervous System - metabolism / Neural Tube Defects - embryology / Neural Tube Defects - genetics / Neural Tube Defects - metabolism / Neural Tube Defects - pathology / Neurology / Nutrients / Physiology / Protein Binding / Proteins / Proteins - metabolism / Regulators / Ribonucleic acids / Science / Vertebrates