title: Mammalian Hippo signalling: a kinase network regulated by protein-protein interactions.
abstract: The Hippo signal transduction cascade controls cell growth, proliferation and death, all of which are frequently deregulated in tumour cells. Since initial studies in Drosophila melanogaster were instrumental in defining Hippo signalling, the machinery was named after the central Ste20-like kinase Hippo. Moreover, given that loss of Hippo signalling components Hippo, Warts, and Mats resulted in uncontrolled tissue overgrowth, Hippo signalling was defined as a tumour-suppressor cascade. Significantly, all of the core factors of Hippo signalling have mammalian orthologues that functionally compensate for loss of their counterparts in Drosophila. Furthermore, studies in Drosophila and mammalian cell systems showed that Hippo signalling represents a kinase cascade that is tightly regulated by PPIs (protein-protein interactions). Several Hippo signalling molecules contain SARAH (Salvador/RASSF1A/Hippo) domains that mediate specific PPIs, thereby influencing the activities of MST1/2 (mammalian Ste20-like serine/threonine kinase 1/2) kinases, the human Hippo orthologues. Moreover, WW domains are present in several Hippo factors, and these domains also serve as interaction surfaces for regulatory PPIs in Hippo signalling. Finally, the kinase activities of LATS1/2 (large tumour-suppressor kinase 1/2), the human counterparts of Warts, are controlled by binding to hMOB1 (human Mps one binder protein 1), the human Mats. Therefore Hippo signalling is regulated by PPIs on several levels. In the present paper, I review the current understanding of how these regulatory PPIs are regulated and contribute to the functionality of Hippo signalling.
authors.affiliation: Tumour Suppressor Signalling Networks Laboratory, UCL Cancer Institute, University College London, London WC1E 6BT, UK. a.hergovich@ucl.ac.uk
authors.forename: Alexander
authors.initials: A
authors.lastname: Hergovich
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D029721:Drosophila Proteins / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D009369:Neoplasms / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D060066:Protein Interaction Maps; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D015398:Signal Transduction; D000099317:Hippo Kinases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D017346:Protein Serine-Threonine Kinases; C109163:STK24 protein, human; D000099317:Hippo Kinases; C499474:hpo protein, Drosophila