title: What is the Hippo pathway? Is the Hippo pathway conserved in Caenorhabditis elegans?
abstract: The Hippo pathway was originally identified in Drosophila as the signalling pathway that governs organ size. The core of the pathway harbours two protein kinases (Hippo and Warts). Hippo phosphorylates and activates Warts, which in turn phosphorylates and inactivates the transcriptional co-activator Yorkie. As Yorkie mediates cell cycle-promoting and anti-apoptotic gene transcriptions, the Hippo pathway suppresses cell cycle progression and induces apoptosis. The pathway was named after Hippo, which was regarded as a key component. The pathway was initially considered to be well conserved in mammals. Indeed the mammalian homologues of Hippo, and Warts negatively regulate Yorkie homologue and function as the tumour suppressors. However, the researchers have identified numerous additional components both in Drosophila and mammals and the significant interspecies diversity is now evident. To make things more complicated, the regulation of the pathway does not necessarily depend on Hippo homologues. In this commentary, we reconsider what is essential for the Hippo pathway and try to sort out the controversial arguments in the discussion of the evolutionary root of the pathway.
authors.affiliation: Department of Medical Biochemistry, Graduate School of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
authors.forename: Zeyu
authors.initials: Z
authors.lastname: Yang
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hata
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001833:Body Temperature Regulation / Q000235:genetics; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D009929:Organ Size / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000091102:YAP-Signaling Proteins; D000099317:Hippo Kinases
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D029742:Caenorhabditis elegans Proteins; D029721:Drosophila Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D015534:Trans-Activators; D014157:Transcription Factors; D000091102:YAP-Signaling Proteins; C581014:YAP-1 protein, C elegans; C503814:Yki protein, Drosophila; C093503:wts protein, Drosophila; C544539:WTS-1 protein, C elegans; C499474:hpo protein, Drosophila; D000099317:Hippo Kinases
keywords: Caenorhabditis elegans; Hippo pathway; Yes-associated protein; evolution; tumour suppressor