The Hippo pathway uses different machinery to control cell fate and organ size

•A subset of Hippo pathway proteins control the fate R8 photoreceptor neurons•Hippo are mostly cytoplasmic, not junctional, in cells•Hippo expressed higher growth phase eye development The is a conserved signaling network that regulates organ and cell fate. One such decision cells Drosophila eye, where specifies whether sense blue or green light. We show only via also regulate choice, including STRIPAK complex, Tao, Pez, 14-3-3 proteins. Furthermore, key were primarily cytoplasmic rather than localized to specific membrane domains, as growing epithelial organs. Additionally, Warts was protein be differentially between subtypes, while central at dramatically lower levels adult pupal eyes larval eyes. Therefore, we reveal several important differences contexts an regulator size, integrating signals from surrounding cells, extracellular matrix, mechanical forces proliferation apoptosis (Gaspar Tapon, 2014Gaspar P. Tapon N. Sensing local environment: actin architecture signalling.Curr. 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Homeostatic Hpo/MST autophosphorylation-dependent recruitment phosphatase complex.Cell Rep. 2017; 3612-3623https://doi.org/10.1016/j.celrep.2017.11.076Abstract (49) Although first identified growth, decisions, subtypes (Jukam 2013Jukam Xie Rister Terrell Charlton-Perkins M.A. Pistillo Gebelein Desplan Cook Opposite feedbacks neural fate.Science. 342: 1238016https://doi.org/10.1126/science.1238016Crossref (59) Jukam Desplan, 2011Jukam Binary Merlin/NF2, Kibra, Lgl, melted maintains postmitotic neuronal fate.Dev. 874-887https://doi.org/10.1016/j.devcel.2011.10.004Abstract (41) Mikeladze-Dvali 2005Mikeladze-Dvali Wernet M.F. Mazzoni E.O. Teleman A.A. Y.W. Cohen S.M. regulators warts/lats interact bistable loop specify opposite fates photoreceptors.Cell. 122: 775-787https://doi.org/10.1016/j.cell.2005.07.026Abstract (135) one eight photosensitive types found subunits called ommatidia. Each specialized subcellular compartment tens thousands microvilli, rhabdomere, projects into space center each ommatidium. rhabdomeres neighboring R7 share same optic path, located proximally 1B–1B′) (Ready, 2002Ready compound morphogenesis: blind engineers?.in: Moses Results Problems Differentiation: Eye Development. 37. Springer-Verlag, 2002: 191-204Google expresses G protein-coupled receptor, distinct spectral sensitivity (known rhodopsins), allowing respond range wavelengths light (Schnaitmann 2013Schnaitmann Garbers Wachtler Tanimoto Color discrimination broadband photoreceptors.Curr. 2375-2382https://doi.org/10.1016/j.cub.2013.10.037Abstract (84) Sharkey 2020Sharkey C.R. Blanco Leibowitz M.M. Pinto-Benito Wardill T.J. photoreceptors.bioRxiv. (2020.04.03.024638)Google mediate color vision can express Rhodopsin 3 (Rh3), Rh4, Rh5, Rh6 (Yamaguchi 2010Yamaguchi Heisenberg Contribution wavelength preference Drosophila.Proc. Natl. Acad. Sci. U S 107: 5634-5639https://doi.org/10.1073/pnas.0809398107Crossref (107) rhodopsin determined subtype two main ommatidia known “pale” (p) “yellow” (y) make up around 30% 70% all ommatidia, respectively. In p subtype, pR7 short UV-sensitive Rh3, whereas pR8 blue-sensitive Rh5. y yR7 long Rh4 yR8 green-sensitive 1C). Specification begins late retina, Spineless, stochastically develop remaining taking on (Johnston 2014Johnston R.J. Interchromosomal communication coordinates intrinsically stochastic expression alleles.Science. 343: 661-665https://doi.org/10.1038/nn.2877Crossref (251) 2006Wernet Celik Duncan Stochastic spineless creates retinal mosaic colour vision.Nature. 440: 174-180https://doi.org/10.1038/nature04615Crossref (266) signal conveyed transforming β instructs become 1C) (Wells 2017Wells B.S. Barnhart Parallel Activin BMP R7/R8 pairing retina.eLife. e25301Crossref (14) controlled feedback Yki, Pleckstrin-homology Melted (Melt) active promote Rh5 its activator, melt, repressor, wts. Wts limits activity, thereby preventing 2019Xie Morton D.B. Opposing post-transcriptional roles binary Hippo-dependent decisions.Dev. 455: 51-59https://doi.org/10.1016/j.ydbio.2019.06.022Crossref (4) 1C–1F). essential maintenance eyes, ensuring sensory overlap Interestingly, although cassette, Sd fate, members do so. For example, Ex; planar polarity regulators, Fat Dachsous; mechanosensors β-Spectrin Ajuba (Jub) choice Pojer 2021Pojer J.M. Saiful Hilmi A.J. Kondo Crumbs apical spectrin cytoskeleton eye.Plos Genet. 2021; e1009146https://doi.org/10.1371/journal.pgen.1009146Crossref (2) 1A). Currently, lack complete understanding participate choice. organs like wing discs, regulated different subdomains. majority resides adherens junctions held inactive Jub (Rauskolb 2014Rauskolb Sun Cytoskeletal tension inhibits Ajuba-Warts complex.Cell. 158: 143-156https://doi.org/10.1016/j.cell.2014.05.035Abstract (205) thought activated when recruited sub-apical region medial membrane, forms complexes Ex, Mer, (Su 2017Su Ludwig M.Z. activate spatially expanded.Dev. 40: 478-490https://doi.org/10.1016/j.devcel.2017.02.004Abstract (50) 2015Sun Reddy B.V.V.G. Localization activation vivo.Nat. Commun. 1-12https://doi.org/10.1038/ncomms9402Crossref (51) highly comprise rhabdomere stalk but these membranes unknown. Here, conducted screen new investigated number 14-3-3ε, 14-3-3ζ. discs largely opposed enriched particular obviously differ subtypes. further investigate role specification, assessed effect genetically depleting Mutations repressors/Yki promoters compromise viability tissues. used Glass Multiple Reporter (lGMR)-Gal4 (Wernet 2003Wernet Labhart Baumann Pichaud Homothorax switches function photoreceptors polarized sensors.Cell. 115: 267-279https://doi.org/10.1016/S0092-8674(03)00848-1Abstract (150) drive RNAi lines minimizing other phenotypes affect development. ratio examined analyzing expressing Rh6, relative 1D, β-gal RNAi, approximately consistent previous studies [Jukam Scholar]). components mask, Hipk, myopic (mop), leash. repressed inactivates dephosphorylating motif Two striatin homologue, Cka, C subunit, Mts Other include adaptor link does may still protein. Depletion Cka (0%–4% across three lines, < 0.001) mts (approximately 12% caused strong increase proportion 2A, 2B, 2D , S1A, S1B). Surprisingly, depletion Slmap did alter (23%–26% 2 > 0.032), suggesting so redundant fashion another 2C, S1C). test second hypothesis, either observed similar (around 22% both, = 0.86) S2A, S1B, S1E). These results indicate Mts, indeed not. context phosphorylating Scholar, 2016Poon Mitchell K.A. Cheng L.Y. neuroblasts brain melanogaster.Curr. 2016; 26: 1034-1042https://doi.org/10.1016/j.cub.2016.02.009Abstract (58) determine depleted resulted moderate 39% 0.0007) 3A 3E ). Consistent this,