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Tripathi BK, Irvine KD. Contributions of the Dachsous intracellular domain to Dachsous-Fat signaling. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.03.587940. [PMID: 38617303 PMCID: PMC11014530 DOI: 10.1101/2024.04.03.587940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
The protocadherins Fat and Dachsous regulate organ growth, shape, patterning, and planar cell polarity. Although Dachsous and Fat have been described as ligand and receptor, respectively, in a signal transduction pathway, there is also evidence for bidirectional signaling. Here we assess signaling downstream of Dachsous through analysis of its intracellular domain. Genomic deletions of conserved sequences within dachsous identified regions of the intracellular domain required for normal development. Deletion of the A motif increased Dachsous protein levels and decreased wing size. Deletion of the D motif decreased Dachsous levels at cell membranes, increased wing size, and disrupted wing, leg and hindgut patterning and planar cell polarity. Co-immunoprecipitation experiments established that the D motif is necessary and sufficient for association of Dachsous with four key partners: Lowfat, Dachs, Spiny-legs, and MyoID. Subdivision of the D motif identified distinct regions that are preferentially responsible for association with Lft versus Dachs. Our results identify motifs that are essential for Dachsous function and are consistent with the hypothesis that the key function of Dachsous is regulation of Fat.
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Fulford AD, Enderle L, Rusch J, Hodzic D, Holder MV, Earl A, Oh RH, Tapon N, McNeill H. Expanded directly binds conserved regions of Fat to restrain growth via the Hippo pathway. J Cell Biol 2023; 222:e202204059. [PMID: 37071483 PMCID: PMC10120405 DOI: 10.1083/jcb.202204059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 11/26/2022] [Accepted: 02/09/2023] [Indexed: 04/19/2023] Open
Abstract
The Hippo pathway is a conserved and critical regulator of tissue growth. The FERM protein Expanded is a key signaling hub that promotes activation of the Hippo pathway, thereby inhibiting the transcriptional co-activator Yorkie. Previous work identified the polarity determinant Crumbs as a primary regulator of Expanded. Here, we show that the giant cadherin Fat also regulates Expanded directly and independently of Crumbs. We show that direct binding between Expanded and a highly conserved region of the Fat cytoplasmic domain recruits Expanded to the apicolateral junctional zone and stabilizes Expanded. In vivo deletion of Expanded binding regions in Fat causes loss of apical Expanded and promotes tissue overgrowth. Unexpectedly, we find Fat can bind its ligand Dachsous via interactions of their cytoplasmic domains, in addition to the known extracellular interactions. Importantly, Expanded is stabilized by Fat independently of Dachsous binding. These data provide new mechanistic insights into how Fat regulates Expanded, and how Hippo signaling is regulated during organ growth.
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Affiliation(s)
- Alexander D. Fulford
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, USA
| | - Leonie Enderle
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Jannette Rusch
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, USA
| | - Didier Hodzic
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, USA
| | - Maxine V. Holder
- Apoptosis and Proliferation Control Laboratory, The Francis Crick Institute, London, UK
| | - Alex Earl
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, USA
| | - Robin Hyunseo Oh
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Nicolas Tapon
- Apoptosis and Proliferation Control Laboratory, The Francis Crick Institute, London, UK
| | - Helen McNeill
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, USA
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
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3
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Gridnev A, Misra JR. Emerging Mechanisms of Growth and Patterning Regulation by Dachsous and Fat Protocadherins. Front Cell Dev Biol 2022; 10:842593. [PMID: 35372364 PMCID: PMC8967653 DOI: 10.3389/fcell.2022.842593] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 02/08/2022] [Indexed: 01/14/2023] Open
Abstract
Dachsous (Ds) and Fat are evolutionarily conserved cell adhesion molecules that play a critical role in development of multiple organ systems, where they coordinate tissue growth and morphogenesis. Much of our understanding of Ds-Fat signaling pathway comes from studies in Drosophila, where they initiate a signaling pathway that regulate growth by influencing Hippo signaling and morphogenesis by regulating Planar Cell Polarity (PCP). In this review, we discuss recent advances in our understanding of the mechanisms by which Ds-Fat signaling pathway regulates these critical developmental processes. Further, we discuss the progress in our understanding about how they function in mammals.
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DeAngelis MW, Coolon JD, Johnson RI. Comparative transcriptome analyses of the Drosophila pupal eye. G3-GENES GENOMES GENETICS 2021; 11:5995320. [PMID: 33561221 PMCID: PMC8043229 DOI: 10.1093/g3journal/jkaa003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 10/08/2020] [Indexed: 12/04/2022]
Abstract
Tissue function is dependent on correct cellular organization and behavior. As a result, the identification and study of genes that contribute to tissue morphogenesis is of paramount importance to the fields of cell and developmental biology. Many of the genes required for tissue patterning and organization are highly conserved between phyla. This has led to the emergence of several model organisms and developmental systems that are used to study tissue morphogenesis. One such model is the Drosophila melanogaster pupal eye that has a highly stereotyped arrangement of cells. In addition, the pupal eye is postmitotic that allows for the study of tissue morphogenesis independent from any effects of proliferation. While the changes in cell morphology and organization that occur throughout pupal eye development are well documented, less is known about the corresponding transcriptional changes that choreograph these processes. To identify these transcriptional changes, we dissected wild-type Canton S pupal eyes and performed RNA-sequencing. Our analyses identified differential expression of many loci that are documented regulators of pupal eye morphogenesis and contribute to multiple biological processes including signaling, axon projection, adhesion, and cell survival. We also identified differential expression of genes not previously implicated in pupal eye morphogenesis such as components of the Toll pathway, several non-classical cadherins, and components of the muscle sarcomere, which could suggest these loci function as novel patterning factors.
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Affiliation(s)
- Miles W DeAngelis
- Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
| | - Joseph D Coolon
- Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
| | - Ruth I Johnson
- Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA
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5
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Fat-regulated adaptor protein Dlish binds the growth suppressor Expanded and controls its stability and ubiquitination. Proc Natl Acad Sci U S A 2019; 116:1319-1324. [PMID: 30606799 PMCID: PMC6347691 DOI: 10.1073/pnas.1811891116] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
To regulate the growth and size of organs, cells can use information from their neighbors to modify intracellular mediators of cell proliferation. The intracellular Hippo pathway is a widely utilized nexus for growth control in animals, but its regulation by extracellular signals is not fully understood. We here identify a pathway that regulates organ size in Drosophila, triggered by the transmembrane receptor, the giant protocadherin Fat. We show that the Fat-regulated SH3 domain adaptor protein Dlish binds to and reduces the stability of the growth suppressor Expanded, a known regulator of the Hippo pathway. The destabilization of Expanded by Dlish works in parallel to a previously established pathway in which Dlish increases levels of the growth-stimulating protein Dachs. The Drosophila protocadherin Fat controls organ size through the Hippo pathway, but the biochemical links to the Hippo pathway components are still poorly defined. We previously identified Dlish, an SH3 domain protein that physically interacts with Fat and the type XX myosin Dachs, and showed that Fat’s regulation of Dlish levels and activity helps limit Dachs-mediated inhibition of Hippo pathway activity. We here characterize a parallel growth control pathway downstream of Fat and Dlish. Using immunoprecipitation and mass spectrometry to search for Dlish partners, we find that Dlish binds the FERM domain growth repressor Expanded (Ex); Dlish SH3 domains directly bind sites in the Ex C terminus. We further show that, in vivo, Dlish reduces the subapical accumulation of Ex, and that loss of Dlish blocks the destabilization of Ex caused by loss of Fat. Moreover, Dlish can bind the F-box E3 ubiquitin ligase Slimb and promote Slimb-mediated ubiquitination of Expanded in vitro. Both the in vitro and in vivo effects of Dlish on Ex require Slimb, strongly suggesting that Dlish destabilizes Ex by helping recruit Slimb-containing E3 ubiquitin ligase complexes to Ex.
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Abstract
To create an intricately patterned and reproducibly sized and shaped organ, many cellular processes must be tightly regulated. Cell elongation, migration, metabolism, proliferation rates, cell-cell adhesion, planar polarization and junctional contractions all must be coordinated in time and space. Remarkably, a pair of extremely large cell adhesion molecules called Fat (Ft) and Dachsous (Ds), acting largely as a ligand-receptor system, regulate, and likely coordinate, these many diverse processes. Here we describe recent exciting progress on how the Ds-Ft pathway controls these diverse processes, and highlight a few of the many questions remaining as to how these enormous cell adhesion molecules regulate development.
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Affiliation(s)
- Seth Blair
- Department of Integrative Biology, University of Wisconsin, Madison, USA
| | - Helen McNeill
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA; Department of Molecular Genetics, University of Toronto, Toronto, Canada; Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Canada.
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7
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Tissue growth and tumorigenesis in Drosophila: cell polarity and the Hippo pathway. Curr Opin Cell Biol 2017; 48:1-9. [PMID: 28364663 DOI: 10.1016/j.ceb.2017.03.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Revised: 03/07/2017] [Accepted: 03/10/2017] [Indexed: 12/17/2022]
Abstract
Cell polarity regulation is critical for defining membrane domains required for the establishment and maintenance of the apical-basal axis in epithelial cells (apico-basal polarity), asymmetric cell divisions, planar organization of tissues (planar cell polarity), and the formation of the front-rear axis in cell migration (front-rear polarity). In the vinegar fly, Drosophila melanogaster, cell polarity regulators also interact with the Hippo tissue growth control signaling pathway. In this review we survey the recent Drosophila literature linking cell polarity regulators with the Hippo pathway in epithelial tissue growth, neural stem cell asymmetric divisions and in cell migration in physiological and tumorigenic settings.
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Misra JR, Irvine KD. Vamana Couples Fat Signaling to the Hippo Pathway. Dev Cell 2016; 39:254-266. [PMID: 27746048 DOI: 10.1016/j.devcel.2016.09.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 08/09/2016] [Accepted: 09/15/2016] [Indexed: 01/08/2023]
Abstract
The protocadherins Dachsous and Fat initiate a signaling pathway that controls growth and planar cell polarity by regulating the membrane localization of the atypical myosin Dachs. How Dachs is regulated by Fat signaling has remained unclear. Here we identify the vamana gene as playing a crucial role in regulating membrane localization of Dachs and in linking Fat and Dachsous to Dachs regulation. Vamana, an SH3-domain-containing protein, physically associates with and co-localizes with Dachs and promotes its membrane localization. Vamana also associates with the Dachsous intracellular domain and with a region of the Fat intracellular domain that is essential for controlling Hippo signaling and levels of Dachs. Epistasis experiments, structure-function analysis, and physical interaction experiments argue that Fat negatively regulates Dachs in a Vamana-dependent process. Our findings establish Vamana as a crucial component of the Dachsous-Fat pathway that transmits Fat signaling by regulating Dachs.
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Affiliation(s)
- Jyoti R Misra
- Department of Molecular Biology and Biochemistry, Howard Hughes Medical Institute, Waksman Institute, Rutgers University, Piscataway NJ 08854, USA
| | - Kenneth D Irvine
- Department of Molecular Biology and Biochemistry, Howard Hughes Medical Institute, Waksman Institute, Rutgers University, Piscataway NJ 08854, USA.
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9
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Saavedra P, Brittle A, Palacios IM, Strutt D, Casal J, Lawrence PA. Planar cell polarity: the Dachsous/Fat system contributes differently to the embryonic and larval stages of Drosophila. Biol Open 2016; 5:397-408. [PMID: 26935392 PMCID: PMC4890672 DOI: 10.1242/bio.017152] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 02/01/2016] [Indexed: 11/20/2022] Open
Abstract
The epidermal patterns of all three larval instars (L1-L3) ofDrosophilaare made by one unchanging set of cells. The seven rows of cuticular denticles of all larval stages are consistently planar polarised, some pointing forwards, others backwards. In L1 all the predenticles originate at the back of the cells but, in L2 and L3, they form at the front or the back of the cell depending on the polarity of the forthcoming denticles. We find that, to polarise all rows, the Dachsous/Fat system is differentially utilised; in L1 it is active in the placement of the actin-based predenticles but is not crucial for the final orientation of the cuticular denticles, in L2 and L3 it is needed for placement and polarity. We find Four-jointed to be strongly expressed in the tendon cells and show how this might explain the orientation of all seven rows. Unexpectedly, we find that L3 that lack Dachsous differ from larvae lacking Fat and we present evidence that this is due to differently mislocalised Dachs. We make some progress in understanding how Dachs contributes to phenotypes of wildtype and mutant larvae and adults.
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Affiliation(s)
- Pedro Saavedra
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 2EJ, UK
| | - Amy Brittle
- Department of Biomedical Science, The University of Sheffield, Sheffield S10 2TN, UK
| | - Isabel M Palacios
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 2EJ, UK
| | - David Strutt
- Department of Biomedical Science, The University of Sheffield, Sheffield S10 2TN, UK
| | - José Casal
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 2EJ, UK
| | - Peter A Lawrence
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 2EJ, UK
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10
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Badouel C, Zander MA, Liscio N, Bagherie-Lachidan M, Sopko R, Coyaud E, Raught B, Miller FD, McNeill H. Fat1 interacts with Fat4 to regulate neural tube closure, neural progenitor proliferation and apical constriction during mouse brain development. Development 2015. [PMID: 26209645 DOI: 10.1242/dev.123539] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mammalian brain development requires coordination between neural precursor proliferation, differentiation and cellular organization to create the intricate neuronal networks of the adult brain. Here, we examined the role of the atypical cadherins Fat1 and Fat4 in this process. We show that mutation of Fat1 in mouse embryos causes defects in cranial neural tube closure, accompanied by an increase in the proliferation of cortical precursors and altered apical junctions, with perturbations in apical constriction and actin accumulation. Similarly, knockdown of Fat1 in cortical precursors by in utero electroporation leads to overproliferation of radial glial precursors. Fat1 interacts genetically with the related cadherin Fat4 to regulate these processes. Proteomic analysis reveals that Fat1 and Fat4 bind different sets of actin-regulating and junctional proteins. In vitro data suggest that Fat1 and Fat4 form cis-heterodimers, providing a mechanism for bringing together their diverse interactors. We propose a model in which Fat1 and Fat4 binding coordinates distinct pathways at apical junctions to regulate neural progenitor proliferation, neural tube closure and apical constriction.
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Affiliation(s)
- Caroline Badouel
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada
| | - Mark A Zander
- Neuroscience and Mental Health Program, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Nicole Liscio
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada
| | | | - Richelle Sopko
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Etienne Coyaud
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, M5G 2M9, Canada
| | - Brian Raught
- Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, M5G 2M9, Canada
| | - Freda D Miller
- Neuroscience and Mental Health Program, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada Institute of Medical Sciences, University of Toronto, Toronto, Ontario, Canada Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Helen McNeill
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
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11
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The Atypical Cadherin Fat Directly Regulates Mitochondrial Function and Metabolic State. Cell 2014; 158:1293-1308. [DOI: 10.1016/j.cell.2014.07.036] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 06/09/2014] [Accepted: 07/10/2014] [Indexed: 11/21/2022]
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12
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Bosch JA, Sumabat TM, Hafezi Y, Pellock BJ, Gandhi KD, Hariharan IK. The Drosophila F-box protein Fbxl7 binds to the protocadherin fat and regulates Dachs localization and Hippo signaling. eLife 2014; 3:e03383. [PMID: 25107277 PMCID: PMC4144329 DOI: 10.7554/elife.03383] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The Drosophila protocadherin Fat (Ft) regulates growth, planar cell polarity (PCP) and proximodistal patterning. A key downstream component of Ft signaling is the atypical myosin Dachs (D). Multiple regions of the intracellular domain of Ft have been implicated in regulating growth and PCP but how Ft regulates D is not known. Mutations in Fbxl7, which encodes an F-box protein, result in tissue overgrowth and abnormalities in proximodistal patterning that phenocopy deleting a specific portion of the intracellular domain (ICD) of Ft that regulates both growth and PCP. Fbxl7 binds to this same portion of the Ft ICD, co-localizes with Ft to the proximal edge of cells and regulates the levels and asymmetry of D at the apical membrane. Fbxl7 can also regulate the trafficking of proteins between the apical membrane and intracellular vesicles. Thus Fbxl7 functions in a subset of pathways downstream of Ft and links Ft to D localization. DOI:http://dx.doi.org/10.7554/eLife.03383.001 Multi-cellular organisms are made up of cells that are organized into tissues and organs that reach a predictable size and shape at the end of their development. To do this, cells must be able to sense their position and orientation within the body and know when to stop growing. Epithelial cells—which make up the outer surface of an animal's body and line the cavities of its internal organs—connect to each other to form flat sheets. These sheets of cells contain structures that are oriented along the plane of the sheet. However, how this so-called ‘planar cell polarity’ coordinates with cell growth in order to build complex tissues and organs remains to be discovered. A protein called Fat is a major player in both planar cell polarity and the Hippo signaling pathway, which controls cell growth. As such, the Fat protein appears to be crucial for controlling the size and shape of organs. Mutations in the Fat protein cause massive tissue overgrowth, prevent planar cell polarity being established correctly, and stop the legs and wings of fruit flies developing normally. The Fat protein also plays a role in distributing another protein called Dachs—which is also part of the Hippo signaling pathway. In epithelial cells of the developing wing, Dachs is mostly located on the side of the cell that is closest to the tip of the developing wing (the so-called ‘distal surface’). How Fat and Dachs work together is not understood, but it is known that they do not bind to each other directly. Now, Bosch et al. show that in the fruit fly Drosophila, the Fat protein binds to another protein called Fbxl7. Flies that cannot produce working Fbxl7 have defects in some aspects of planar cell polarity and a modest increase in tissue growth. Fbxl7 seems to account for part, but not all, of the ability of Fat to restrict tissue growth. Furthermore, a lack of the Fbxl7 protein results in a spreading of Dachs protein across the apical surface—which faces out of the epithelial sheet—of epithelial cells. On the other hand, if Fbxl7 is over-expressed, Dachs is driven to the interior of each cell. Hence, a normal level of Fbxl7 protein restricts the Dachs protein to the correct parts of the cell surface. Together, the findings of Bosch et al. show that the Fbxl7 protein is a key link between the Fat and Dachs proteins. These results also provide an understanding of how growth and planar cell polarity—two processes that are essential for normal development of all multi-cellular organisms—are coordinated. DOI:http://dx.doi.org/10.7554/eLife.03383.002
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Affiliation(s)
- Justin A Bosch
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Taryn M Sumabat
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Yassi Hafezi
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Brett J Pellock
- Department of Biology, Providence College, Providence, United States
| | - Kevin D Gandhi
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Iswar K Hariharan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
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13
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Abstract
Planar cell polarity (PCP) in epithelia, orthogonal to the apical-basal axis, is essential for numerous developmental events and physiological functions. Drosophila model systems have been at the forefront of studies revealing insights into mechanisms regulating PCP and have revealed distinct signaling modules. One of these, involving the atypical cadherins Fat and Dachsous and the ectokinase Four-jointed, appears to link the direction of cell polarization to the tissue axes. We discuss models for the function of this signaling module as well as several unanswered questions that may guide future investigations.
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Affiliation(s)
- Maja Matis
- Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA
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14
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Abstract
The Hippo pathway is a kinase cascade, formed by Hippo, Salvador, Warts, and Mats, that regulates the subcellular distribution and transcriptional activity of Yorkie. Yorkie is a transcriptional coactivator that promotes the expression of genes that inhibit apoptosis and drive cell proliferation. We review recent studies indicating that activity of the Hippo pathway is controlled by cell-cell junctions, cell adhesion molecules, scaffolding proteins, and cytoskeletal proteins, as well as by regulators of apical-basal polarity and extracellular tension.
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Affiliation(s)
- Leonie Enderle
- 1Biozentrum, University of Basel, 4056 Basel, Switzerland
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15
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Lawlor KT, Ly DC, DiNardo S. Drosophila Dachsous and Fat polarize actin-based protrusions over a restricted domain of the embryonic denticle field. Dev Biol 2013; 383:285-94. [PMID: 24051227 DOI: 10.1016/j.ydbio.2013.09.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 09/02/2013] [Accepted: 09/05/2013] [Indexed: 12/16/2022]
Abstract
Atypical cadherins Dachsous (Ds) and Fat coordinate the establishment of planar polarity, essential for the patterning of complex tissues and organs. The precise mechanisms by which this system acts, particularly in cases where Ds and Fat act independently of the 'core' frizzled system, are still the subject of investigation. Examining the deployment of the Ds-Fat system in different tissues of the model organism Drosophila, has provided insights into the general mechanisms by which polarity is established and propagated to coordinate outcomes across a field of cells. The Drosophila embryonic epidermis provides a simple model epithelia where the establishment of polarity can be observed from start to finish, and in the absence of proliferation, over a fixed number of cells. Using the asymmetric placement of f-actin during denticle assembly as a read-out of polarity, we examine the requirement for Ds and Fat in establishing polarity across the denticle field. Comparing detailed phenotypic analysis with steady state protein enrichment revealed a spatially restricted requirement for the Ds-Fat system within the posterior denticle field. Ectopic Ds signaling provides evidence for a model whereby Ds acts to asymmetrically enrich Fat in a neighboring cell, in turn polarizing the cell to specify the position of the actin-based protrusions at the cell cortex.
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Affiliation(s)
- Kynan T Lawlor
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, United States
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16
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Sharma P, McNeill H. Regulation of long-range planar cell polarity by Fat-Dachsous signaling. Development 2013; 140:3869-81. [PMID: 23946440 DOI: 10.1242/dev.094730] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Fat (Ft) and Dachsous (Ds) are large cadherins that bind each other and have conserved roles in regulating planar cell polarity (PCP). We quantitatively analyzed Ft-Ds pathway mutant clones for their effects on ommatidial polarity in the Drosophila eye. Our findings suggest that the Ft-Ds pathway regulates PCP propagation independently of asymmetric cellular accumulation of Ft or Ds. We find that the Ft effector Atrophin has a position-specific role in regulating polarity in the eye, and that asymmetric accumulation of the atypical myosin Dachs is not essential for production and propagation of a long-range PCP signal. Our observations suggest that Ft and Ds interact to modulate a secondary signal that regulates long-range polarity, that signaling by the Ds intracellular domain is dependent on Ft, and that ommatidial fate specification is genetically separable from long-range signaling.
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Affiliation(s)
- Praveer Sharma
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada
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