Zyxin antagonizes the FERM protein expanded to couple F-actin and Yorkie-dependent organ growth.
BACKGROUND
Coordinated multicellular growth during development is achieved by the sensing of spatial and nutritional boundaries. The conserved Hippo (Hpo) signaling pathway has been proposed to restrict tissue growth by perceiving mechanical constraints through actin cytoskeleton networks. The actin-associated LIM proteins Zyxin (Zyx) and Ajuba (Jub) have been linked to the control of tissue growth via regulation of Hpo signaling, but the study of Zyx has been hampered by a lack of genetic tools.


RESULTS
We generated a zyx mutant in Drosophila using TALEN endonucleases and used this to show that Zyx antagonizes the FERM-domain protein Expanded (Ex) to control tissue growth, eye differentiation, and F-actin accumulation. Zyx membrane targeting promotes the interaction between the transcriptional co-activator Yorkie (Yki) and the transcription factor Scalloped (Sd), leading to activation of Yki target gene expression and promoting tissue growth. Finally, we show that Zyx's growth-promoting function is dependent on its interaction with the actin-associated protein Enabled (Ena) via a conserved LPPPP motif and is antagonized by Capping Protein (CP).


CONCLUSIONS
Our results show that Zyx is a functional antagonist of Ex in growth control and establish a link between actin filament polymerization and Yki activity.
Apoptosis and Proliferation Control Laboratory, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK; Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal.
Pedro
P
Gaspar
Apoptosis and Proliferation Control Laboratory, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK.
Maxine V
MV
Holder
Apoptosis and Proliferation Control Laboratory, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK.
Birgit L
BL
Aerne
Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal. Electronic address: fjanody@igc.gulbenkian.pt.
Florence
F
Janody
Apoptosis and Proliferation Control Laboratory, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK. Electronic address: nic.tapon@cancer.org.uk.
Nicolas
N
Tapon
D000199:Actins / Q000502:physiology*; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics / Q000502:physiology*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*; D005123:Eye / Q000254:growth & development / Q000378:metabolism; D005260:Female; D017344:Genes, Insect; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000235:genetics / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology*; D009929:Organ Size / Q000235:genetics / Q000502:physiology; D038081:Organogenesis / Q000235:genetics / Q000502:physiology; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*; D014921:Wings, Animal / Q000254:growth & development / Q000378:metabolism; D000091102:YAP-Signaling Proteins; D060589:Zyxin / Q000235:genetics / Q000502:physiology*
D000199:Actins; D029721:Drosophila Proteins; D008565:Membrane Proteins; D050505:Mutant Proteins; D009687:Nuclear Proteins; D015534:Trans-Activators; D000091102:YAP-Signaling Proteins; C503814:Yki protein, Drosophila; C499520:Zyx protein, Drosophila; D060589:Zyxin; C085090:ex protein, Drosophila; D004247:DNA