The WW Domain Protein Kibra Acts Upstream of Hippo in Drosophila

• Published in: Developmental cell Vol. 18; no. 2; pp. 309 - 316
• Main Authors: Baumgartner, Roland, Poernbacher, Ingrid, Buser, Nathalie, Hafen, Ernst, Stocker, Hugo
• Format: Journal Article
• Language: English
• Published: Cambridge, MA Elsevier Inc 16.02.2010; Cell Press
• Subjects: Animals; Animals, Genetically Modified; Apoptosis; Biological and medical sciences; Cell Count; Cell differentiation, maturation, development, hematopoiesis; Cell Line; Cell physiology; CELLCYCLE; DEVBIO; Drosophila; Drosophila - genetics; Drosophila - growth & development; Drosophila - physiology; Drosophila Proteins - chemistry; Drosophila Proteins - genetics; Drosophila Proteins - physiology; Epistasis, Genetic; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Developmental; Genes, Insect; Intracellular Signaling Peptides and Proteins - genetics; Intracellular Signaling Peptides and Proteins - physiology; Membrane Proteins - genetics; Membrane Proteins - physiology; Molecular and cellular biology; Mutation; Neurofibromin 2 - genetics; Neurofibromin 2 - physiology; Nuclear Proteins - genetics; Nuclear Proteins - physiology; Organ Size; Protein Structure, Tertiary; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - physiology; Signal Transduction; SIGNALING; Trans-Activators - genetics; Trans-Activators - physiology; Tumor Suppressor Proteins - chemistry; Tumor Suppressor Proteins - genetics; Tumor Suppressor Proteins - physiology; CELLCYCLE; DEVBIO; SIGNALING; Arthropoda; Insecta; Development; Invertebrata; Drosophila melanogaster; Diptera; Protein; Drosophilidae
• ISSN: 1534-5807; 1878-1551
• DOI: 10.1016/j.devcel.2009.12.013

The conserved Hippo kinase pathway plays a pivotal role in organ size control and tumor suppression by restricting proliferation and promoting apoptosis. Whereas the function of the core kinase cascade, consisting of the serine/threonine kinases Hippo and Warts, in phosphorylating and thereby inactivating the transcriptional coactivator Yorkie is well established, much less is known about the upstream events that regulate Hippo signaling activity. The FERM domain proteins Expanded and Merlin appear to represent two different signaling branches that feed into the Hippo pathway. Signaling by the atypical cadherin Fat may act via Expanded, but how Merlin is regulated has remained elusive. Here, we show that the WW domain protein Kibra is a Hippo signaling component upstream of Hippo and Merlin. Kibra acts synergistically with Expanded, and it physically interacts with Merlin. Thus, Kibra predominantly acts in the Merlin branch upstream of the core kinase cascade to regulate Hippo signaling. [Display omitted] ► The WW domain protein Kibra is a Hippo signalling component ► Kibra restricts organ size via Yorkie and acts upstream of Hippo and Merlin ► Kibra synergizes with Expanded and binds to Merlin