The Endosomal Protein Appl1 Mediates Akt Substrate Specificity and Cell Survival in Vertebrate Development Annette Schenck,1,4 Livia Goto-Silva,1 Claudio Collinet,1 Muriel Rhinn,2,5 Angelika Giner,1 Bianca Habermann,1,3 Michael Brand,2 and Marino Zerial1,* 1Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany 2Biotechnology Center and Center for Regenerative Therapies, University of Technology Dresden, Tatzberg 47-51, 01307 Dresden, Germany 3Scionics Computer Innovation GmbH, Tatzberg 47, 01307 Dresden, Germany 4Present address: Department of Human Genetics, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Geert Grooteplein 10, 6525 GA Nijmegen, The Netherlands. 5Present address: Institut de Ge´ ne´ tique et de Biologie Mole´ culaire et Cellulaire, CNRS/INSERM/ULP, Boite Postal 10142, 67404 Illkirch Cedex, France. *Correspondence:
[email protected] DOI 10.1016/j.cell.2008.02.044 SUMMARY grown in the past decade, uncovering central signaling hubs such protein kinase B (Akt) and mitogen-activated protein During development of multicellular organisms, cells kinases (MAPK) (Dhillon et al., 2007; Manning and Cantley, respond to extracellular cues through nonlinear sig- 2007). However, our understanding of the mechanisms underly- nal transduction cascades whose principal compo- ing the specificity of signal transmission and processing requires nents have been identified. Nevertheless, the molec- new conceptual advances. Signaling components such as ular mechanisms underlying specificity of cellular kinases often possess various potential substrates, leading to responses remain poorly understood. Spatial distri- highly branched signaling networks rather than linear cascades. This poses the problem of how a physiological response can be bution of signaling proteins may contribute to signal- elicited with high specificity, with information flowing through ing specificity.