1
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Li RG, Martin JF. Legend of MERLIN and the Quest for Cardiac Lineage Commitment. Circulation 2024; 149:1980-1981. [PMID: 38885302 PMCID: PMC11185273 DOI: 10.1161/circulationaha.123.065901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Affiliation(s)
- Rich Gang Li
- Cardiomyocyte Renewal Laboratory, Texas Heart Institute, Houston, TX, 77030
- McGill Gene Editing Laboratory, Texas Heart Institute, Houston, TX, 77030
| | - James F. Martin
- Cardiomyocyte Renewal Laboratory, Texas Heart Institute, Houston, TX, 77030
- McGill Gene Editing Laboratory, Texas Heart Institute, Houston, TX, 77030
- Department of Integrative Physiology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030
- Center for Organ Repair and Renewal, Baylor College of Medicine, One Baylor Plaza, Houston, TX, 77030
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2
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Lee CJM, Autio MI, Zheng W, Song Y, Wang SC, Wong DCP, Xiao J, Zhu Y, Yusoff P, Yei X, Chock WK, Low BC, Sudol M, Foo RSY. Genome-Wide CRISPR Screen Identifies an NF2-Adherens Junction Mechanistic Dependency for Cardiac Lineage. Circulation 2024; 149:1960-1979. [PMID: 38752370 DOI: 10.1161/circulationaha.122.061335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Accepted: 04/05/2024] [Indexed: 06/19/2024]
Abstract
BACKGROUND Cardiomyocyte differentiation involves a stepwise clearance of repressors and fate-restricting regulators through the modulation of BMP (bone morphogenic protein)/Wnt-signaling pathways. However, the mechanisms and how regulatory roadblocks are removed with specific developmental signaling pathways remain unclear. METHODS We conducted a genome-wide CRISPR screen to uncover essential regulators of cardiomyocyte specification in human embryonic stem cells using a myosin heavy chain 6 (MYH6)-GFP (green fluorescence protein) reporter system. After an independent secondary single guide ribonucleic acid validation of 25 candidates, we identified NF2 (neurofibromin 2), a moesin-ezrin-radixin like (MERLIN) tumor suppressor, as an upstream driver of early cardiomyocyte lineage specification. Independent monoclonal NF2 knockouts were generated using CRISPR-Cas9, and cell states were inferred through bulk RNA sequencing and protein expression analysis across differentiation time points. Terminal lineage differentiation was assessed by using an in vitro 2-dimensional-micropatterned gastruloid model, trilineage differentiation, and cardiomyocyte differentiation. Protein interaction and post-translation modification of NF2 with its interacting partners were assessed using site-directed mutagenesis, coimmunoprecipitation, and proximity ligation assays. RESULTS Transcriptional regulation and trajectory inference from NF2-null cells reveal the loss of cardiomyocyte identity and the acquisition of nonmesodermal identity. Sustained elevation of early mesoderm lineage repressor SOX2 and upregulation of late anticardiac regulators CDX2 and MSX1 in NF2 knockout cells reflect a necessary role for NF2 in removing regulatory roadblocks. Furthermore, we found that NF2 and AMOT (angiomotin) cooperatively bind to YAP (yes-associated protein) during mesendoderm formation, thereby preventing YAP activation, independent of canonical MST (mammalian sterile 20-like serine-threonine protein kinase)-LATS (large tumor suppressor serine-threonine protein kinase) signaling. Mechanistically, cardiomyocyte lineage identity was rescued by wild-type and NF2 serine-518 phosphomutants, but not NF2 FERM (ezrin-radixin-meosin homology protein) domain blue-box mutants, demonstrating that the critical FERM domain-dependent formation of the AMOT-NF2-YAP scaffold complex at the adherens junction is required for early cardiomyocyte lineage differentiation. CONCLUSIONS These results provide mechanistic insight into the essential role of NF2 during early epithelial-mesenchymal transition by sequestering the repressive effect of YAP and relieving regulatory roadblocks en route to cardiomyocytes.
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Affiliation(s)
- Chang Jie Mick Lee
- Cardiovascular Metabolic Disease Translational Research Programme, National University Health System, Centre for Translational Medicine, Singapore (C.J.M.L., W.H.Z., Y.Z., P.Y., X.Y., R.S.-Y.F.)
- Institute of Molecular and Cell Biology, Singapore (C.J.M.L., Y.Z., R.S.-Y.F.)
| | | | - Wenhao Zheng
- Cardiovascular Metabolic Disease Translational Research Programme, National University Health System, Centre for Translational Medicine, Singapore (C.J.M.L., W.H.Z., Y.Z., P.Y., X.Y., R.S.-Y.F.)
| | - Yoohyun Song
- Mechanobiology Institute Singapore (Y.S., S.C.W., D.C.P.W., J.X., B.C.L.), National University of Singapore
- Institute of Bioengineering and Bioimaging, Agency for Science, Technology and Research (A*STAR), Singapore (Y.S., S.C.W.)
| | - Shyi Chyi Wang
- Mechanobiology Institute Singapore (Y.S., S.C.W., D.C.P.W., J.X., B.C.L.), National University of Singapore
- Institute of Bioengineering and Bioimaging, Agency for Science, Technology and Research (A*STAR), Singapore (Y.S., S.C.W.)
| | - Darren Chen Pei Wong
- Mechanobiology Institute Singapore (Y.S., S.C.W., D.C.P.W., J.X., B.C.L.), National University of Singapore
- Department of Biological Sciences (D.C.P.W., B.C.L.), National University of Singapore
| | - Jingwei Xiao
- Mechanobiology Institute Singapore (Y.S., S.C.W., D.C.P.W., J.X., B.C.L.), National University of Singapore
| | - Yike Zhu
- Cardiovascular Metabolic Disease Translational Research Programme, National University Health System, Centre for Translational Medicine, Singapore (C.J.M.L., W.H.Z., Y.Z., P.Y., X.Y., R.S.-Y.F.)
- Institute of Molecular and Cell Biology, Singapore (C.J.M.L., Y.Z., R.S.-Y.F.)
| | - Permeen Yusoff
- Cardiovascular Metabolic Disease Translational Research Programme, National University Health System, Centre for Translational Medicine, Singapore (C.J.M.L., W.H.Z., Y.Z., P.Y., X.Y., R.S.-Y.F.)
| | - Xi Yei
- Cardiovascular Metabolic Disease Translational Research Programme, National University Health System, Centre for Translational Medicine, Singapore (C.J.M.L., W.H.Z., Y.Z., P.Y., X.Y., R.S.-Y.F.)
| | | | - Boon Chuan Low
- Mechanobiology Institute Singapore (Y.S., S.C.W., D.C.P.W., J.X., B.C.L.), National University of Singapore
- Department of Biological Sciences (D.C.P.W., B.C.L.), National University of Singapore
- University Scholars Programme (B.C.L.), National University of Singapore
| | - Marius Sudol
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York (M.S.)
| | - Roger S-Y Foo
- Cardiovascular Metabolic Disease Translational Research Programme, National University Health System, Centre for Translational Medicine, Singapore (C.J.M.L., W.H.Z., Y.Z., P.Y., X.Y., R.S.-Y.F.)
- Institute of Molecular and Cell Biology, Singapore (C.J.M.L., Y.Z., R.S.-Y.F.)
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3
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Doddihal V, Mann FG, Ross EJ, McKinney MC, Guerrero-Hernández C, Brewster CE, McKinney SA, Sánchez Alvarado A. A PAK family kinase and the Hippo/Yorkie pathway modulate WNT signaling to functionally integrate body axes during regeneration. Proc Natl Acad Sci U S A 2024; 121:e2321919121. [PMID: 38713625 PMCID: PMC11098123 DOI: 10.1073/pnas.2321919121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 04/03/2024] [Indexed: 05/09/2024] Open
Abstract
Successful regeneration of missing tissues requires seamless integration of positional information along the body axes. Planarians, which regenerate from almost any injury, use conserved, developmentally important signaling pathways to pattern the body axes. However, the molecular mechanisms which facilitate cross talk between these signaling pathways to integrate positional information remain poorly understood. Here, we report a p21-activated kinase (smed-pak1) which functionally integrates the anterior-posterior (AP) and the medio-lateral (ML) axes. pak1 inhibits WNT/β-catenin signaling along the AP axis and, functions synergistically with the β-catenin-independent WNT signaling of the ML axis. Furthermore, this functional integration is dependent on warts and merlin-the components of the Hippo/Yorkie (YKI) pathway. Hippo/YKI pathway is a critical regulator of body size in flies and mice, but our data suggest the pathway regulates body axes patterning in planarians. Our study provides a signaling network integrating positional information which can mediate coordinated growth and patterning during planarian regeneration.
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Affiliation(s)
- Viraj Doddihal
- Stowers Institute for Medical Research, Kansas City, MO64110
| | | | - Eric J. Ross
- Stowers Institute for Medical Research, Kansas City, MO64110
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4
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Pipchuk A, Kelly T, Carew M, Nicol C, Yang X. Development of Novel Bioluminescent Biosensors Monitoring the Conformation and Activity of the Merlin Tumour Suppressor. Int J Mol Sci 2024; 25:1527. [PMID: 38338806 PMCID: PMC10855677 DOI: 10.3390/ijms25031527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Revised: 01/23/2024] [Accepted: 01/24/2024] [Indexed: 02/12/2024] Open
Abstract
Solid tumours can universally evade contact inhibition of proliferation (CIP), a mechanism halting cell proliferation when cell-cell contact occurs. Merlin, an ERM-like protein, crucially regulates CIP and is frequently deactivated in various cancers, indicating its significance as a tumour suppressor in cancer biology. Despite extensive investigations into Merlin's role in cancer, its lack of intrinsic catalytic activity and frequent conformation changes have made it notoriously challenging to study. To address this challenge, we harnessed innovative luciferase technologies to create and validate a NanoBiT split-luciferase biosensor system in which Merlin is cloned between two split components (LgBiT and SmBiT) of NanoLuc luciferase. This system enables precise quantification of Merlin's conformation and activity both in vitro and within living cells. This biosensor significantly enhances the study of Merlin's molecular functions, serving as a potent tool for exploring its contributions to CIP and tumorigenesis.
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Affiliation(s)
| | | | | | | | - Xiaolong Yang
- Department of Pathology and Molecular Medicine, Queen’s University, Kingston, ON K7L 3N6, Canada; (A.P.); (T.K.); (M.C.); (C.N.)
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5
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Moesslacher CS, Auernig E, Woodsmith J, Feichtner A, Jany-Luig E, Jehle S, Worseck JM, Heine CL, Stefan E, Stelzl U. Missense variant interaction scanning reveals a critical role of the FERM domain for tumor suppressor protein NF2 conformation and function. Life Sci Alliance 2023; 6:e202302043. [PMID: 37280085 PMCID: PMC10244618 DOI: 10.26508/lsa.202302043] [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: 03/16/2023] [Revised: 05/24/2023] [Accepted: 05/24/2023] [Indexed: 06/08/2023] Open
Abstract
NF2 (moesin-ezrin-radixin-like [MERLIN] tumor suppressor) is frequently inactivated in cancer, where its NF2 tumor suppressor functionality is tightly coupled to protein conformation. How NF2 conformation is regulated and how NF2 conformation influences tumor suppressor activity is a largely open question. Here, we systematically characterized three NF2 conformation-dependent protein interactions utilizing deep mutational scanning interaction perturbation analyses. We identified two regions in NF2 with clustered mutations which affected conformation-dependent protein interactions. NF2 variants in the F2-F3 subdomain and the α3H helix region substantially modulated NF2 conformation and homomerization. Mutations in the F2-F3 subdomain altered proliferation in three cell lines and matched patterns of disease mutations in NF2 related-schwannomatosis. This study highlights the power of systematic mutational interaction perturbation analysis to identify missense variants impacting NF2 conformation and provides insight into NF2 tumor suppressor function.
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Affiliation(s)
- Christina S Moesslacher
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Elisabeth Auernig
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Jonathan Woodsmith
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Andreas Feichtner
- Institute of Biochemistry and Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Evelyne Jany-Luig
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Stefanie Jehle
- Max-Planck Institute for Molecular Genetics (MPIMG), Otto-Warburg-Laboratory, Berlin, Germany
| | - Josephine M Worseck
- Max-Planck Institute for Molecular Genetics (MPIMG), Otto-Warburg-Laboratory, Berlin, Germany
| | - Christian L Heine
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Eduard Stefan
- Institute of Biochemistry and Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
- Tyrolean Cancer Research Institute (TKFI), Innsbruck, Austria
- Institute of Molecular Biology, Innsbruck, Austria
| | - Ulrich Stelzl
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
- Max-Planck Institute for Molecular Genetics (MPIMG), Otto-Warburg-Laboratory, Berlin, Germany
- BioTechMed-Graz, Graz, Austria
- Field of Excellence BioHealth - University of Graz, Graz, Austria
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6
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Zhou J, Dabiri Y, Gama-Brambila RA, Ghafoory S, Altinbay M, Mehrabi A, Golriz M, Blagojevic B, Reuter S, Han K, Seidel A, Đikić I, Wölfl S, Cheng X. pVHL-mediated SMAD3 degradation suppresses TGF-β signaling. J Cell Biol 2022; 221:212891. [PMID: 34860252 PMCID: PMC8650352 DOI: 10.1083/jcb.202012097] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 06/07/2021] [Accepted: 10/13/2021] [Indexed: 12/20/2022] Open
Abstract
Transforming growth factor β (TGF-β) signaling plays a fundamental role in metazoan development and tissue homeostasis. However, the molecular mechanisms concerning the ubiquitin-related dynamic regulation of TGF-β signaling are not thoroughly understood. Using a combination of proteomics and an siRNA screen, we identify pVHL as an E3 ligase for SMAD3 ubiquitination. We show that pVHL directly interacts with conserved lysine and proline residues in the MH2 domain of SMAD3, triggering degradation. As a result, the level of pVHL expression negatively correlates with the expression and activity of SMAD3 in cells, Drosophila wing, and patient tissues. In Drosophila, loss of pVHL leads to the up-regulation of TGF-β targets visible in a downward wing blade phenotype, which is rescued by inhibition of SMAD activity. Drosophila pVHL expression exhibited ectopic veinlets and reduced wing growth in a similar manner as upon loss of TGF-β/SMAD signaling. Thus, our study demonstrates a conserved role of pVHL in the regulation of TGF-β/SMAD3 signaling in human cells and Drosophila wing development.
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Affiliation(s)
- Jun Zhou
- School of Biomedical Sciences, Hunan University, Changsha, China.,Division of Signaling and Functional Genomics, Department of Cell and Molecular Biology, Medical Faculty Mannheim, German Cancer Research Center and Heidelberg University, Heidelberg, Germany
| | - Yasamin Dabiri
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Rodrigo A Gama-Brambila
- Buchmann Institute for Molecular Life Sciences, Pharmaceutical Chemistry, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - Shahrouz Ghafoory
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Mukaddes Altinbay
- Buchmann Institute for Molecular Life Sciences, Pharmaceutical Chemistry, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - Arianeb Mehrabi
- Department of General, Visceral and Transplantation Surgery, Heidelberg University, Heidelberg, Germany
| | - Mohammad Golriz
- Department of General, Visceral and Transplantation Surgery, Heidelberg University, Heidelberg, Germany
| | - Biljana Blagojevic
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Stefanie Reuter
- Universitätsklinikum Jena, Klinik für Innere Medizin III, Jena, Germany
| | - Kang Han
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Anna Seidel
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Ivan Đikić
- Buchmann Institute for Molecular Life Sciences, Pharmaceutical Chemistry, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
| | - Stefan Wölfl
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany
| | - Xinlai Cheng
- Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Heidelberg, Germany.,Buchmann Institute for Molecular Life Sciences, Pharmaceutical Chemistry, Goethe University Frankfurt am Main, Frankfurt am Main, Germany
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7
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Karasek C, Ashry M, Driscoll CS, Knott JG. A tale of two cell-fates: role of the Hippo signaling pathway and transcription factors in early lineage formation in mouse preimplantation embryos. Mol Hum Reprod 2021; 26:653-664. [PMID: 32647873 PMCID: PMC7473788 DOI: 10.1093/molehr/gaaa052] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/18/2020] [Indexed: 12/26/2022] Open
Abstract
In mammals, the first cell-fate decision occurs during preimplantation embryo development when the inner cell mass (ICM) and trophectoderm (TE) lineages are established. The ICM develops into the embryo proper, while the TE lineage forms the placenta. The underlying molecular mechanisms that govern lineage formation involve cell-to-cell interactions, cell polarization, cell signaling and transcriptional regulation. In this review, we will discuss the current understanding regarding the cellular and molecular events that regulate lineage formation in mouse preimplantation embryos with an emphasis on cell polarity and the Hippo signaling pathway. Moreover, we will provide an overview on some of the molecular tools that are used to manipulate the Hippo pathway and study cell-fate decisions in early embryos. Lastly, we will provide exciting future perspectives on transcriptional regulatory mechanisms that modulate the activity of the Hippo pathway in preimplantation embryos to ensure robust lineage segregation.
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Affiliation(s)
- Challis Karasek
- Developmental Epigenetics Laboratory, Department of Animal Science, Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, USA
| | - Mohamed Ashry
- Developmental Epigenetics Laboratory, Department of Animal Science, Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, USA
| | - Chad S Driscoll
- Developmental Epigenetics Laboratory, Department of Animal Science, Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, USA
| | - Jason G Knott
- Developmental Epigenetics Laboratory, Department of Animal Science, Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, USA
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8
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Primi MC, Rangarajan ES, Patil DN, Izard T. Conformational flexibility determines the Nf2/merlin tumor suppressor functions. Matrix Biol Plus 2021; 12:100074. [PMID: 34337379 PMCID: PMC8318988 DOI: 10.1016/j.mbplus.2021.100074] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/14/2021] [Accepted: 06/15/2021] [Indexed: 10/26/2022] Open
Abstract
The Neurofibromatosis type 2 gene encodes the Nf2/merlin tumor suppressor protein that is responsible for the regulation of cell proliferation. Once activated, Nf2/merlin modulates adhesive signaling pathways and thereby inhibits cell growth. Nf2/merlin controls oncogenic gene expression by modulating the Hippo pathway. By responding to several physical and biochemical stimuli, Hippo signaling determines contact inhibition of proliferation as well as organ size. The large tumor suppressor (LATS) serine/threonine-protein kinase is the key enzyme in the highly conserved kinase cascade that negatively regulates the activity and localization of the transcriptional coactivators Yes-associated protein (YAP) and its paralogue transcriptional coactivator with PDZ-binding motif (TAZ). Nf2/merlin belongs to the band 4.1, ezrin, radixin, moesin (FERM) gene family that links the actin cytoskeleton to adherens junctions, remodels adherens junctions during epithelial morphogenesis and maintains organized apical surfaces on the plasma cell membrane. Nf2/merlin and ERM proteins have a globular N-terminal cloverleaf head domain, the FERM domain, that binds to the plasma membrane, a central α-helical domain, and a tail domain that binds to its head domain. Here we present the high-resolution crystal structure of Nf2/merlin bound to LATS1 which shows that LATS1 binding to Nf2/merlin displaces the Nf2/merlin tail domain and causes an allosteric shift in the Nf2/merlin α-helix that extends from its FERM domain. This is consistent with the fact that full-length Nf2/merlin binds LATS1 ~10-fold weaker compared to LATS1 binding to the Nf2/merlin-PIP2 complex. Our data increase our understanding of Nf2/merlin biology by providing mechanistic insights into the Hippo pathway that are relevant to several diseases in particular oncogenic features that are associated with cancers.
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Affiliation(s)
- Marina C Primi
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter 33458, FL, United States
| | - Erumbi S Rangarajan
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter 33458, FL, United States
| | - Dipak N Patil
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter 33458, FL, United States
| | - Tina Izard
- Cell Adhesion Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, Jupiter 33458, FL, United States
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9
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Johnson B, Leatherman J. Merlin and expanded integrate cell signaling that regulates cyst stem cell proliferation in the Drosophila testis niche. Dev Biol 2021; 477:133-144. [PMID: 34044021 DOI: 10.1016/j.ydbio.2021.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 05/13/2021] [Accepted: 05/16/2021] [Indexed: 09/30/2022]
Abstract
The Drosophila testis is a model organism stem cell niche in which two stem cell populations coordinate together to produce sperm; thus, these stem cells must be balanced in the niche. Merlin, a tumor-suppressor and human disease gene required for contact inhibition of proliferation, is known to limit the proliferation of the somatic cyst stem cells in the testis niche. Expanded encodes a protein that is structurally similar to Merlin in Drosophila, and is semi-redundant with Merlin in multiple tissues. We found that expanded depletion caused similar cyst lineage cell over-proliferation as observed with Merlin, and double mutants showed more severe phenotypes than either gene individually. Thus, these genes have partially redundant functions in the cyst lineage cells of this niche. We also expressed non-phosphorylatable constitutively "tumor suppressing" alleles of Merlin in cyst lineage cells, and surprisingly, we observed a similar cyst lineage over-proliferation phenotype. Merlin is known to impact multiple different signaling pathways to exert its effect on proliferation. We found that the Merlin loss of function phenotype was associated with an increase in MAPK/ERK signaling, consistent with Merlin's established role in transmembrane receptor inhibition. Constitutive Merlin displayed a reduction in both MAPK/ERK signaling and PI3K/Tor signaling. PI3K/Tor signaling is required for cyst cell differentiation, and inhibition of this pathway by Merlin activation phenocopied the Tor cyst lineage loss of function phenotype. Thus, Merlin impacts and integrates the activity of multiple signaling pathways in the testis niche. The ability of Merlin to dynamically change its activity via phosphorylation in response to local contact cues provides an intriguing mechanism whereby the signaling pathways that control these stem cells might be dynamically regulated in response to the division of a neighboring germ cell.
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Affiliation(s)
- Bryan Johnson
- School of Biological Sciences, University of Northern Colorado, Greeley, CO, USA
| | - Judith Leatherman
- School of Biological Sciences, University of Northern Colorado, Greeley, CO, USA.
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10
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Tokamov SA, Su T, Ullyot A, Fehon RG. Negative feedback couples Hippo pathway activation with Kibra degradation independent of Yorkie-mediated transcription. eLife 2021; 10:62326. [PMID: 33555257 PMCID: PMC7895526 DOI: 10.7554/elife.62326] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 02/08/2021] [Indexed: 12/20/2022] Open
Abstract
The Hippo (Hpo) pathway regulates tissue growth in many animals. Multiple upstream components promote Hpo pathway activity, but the organization of these different inputs, the degree of crosstalk between them, and whether they are regulated in a distinct manner is not well understood. Kibra (Kib) activates the Hpo pathway by recruiting the core Hpo kinase cassette to the apical cortex. Here, we show that the Hpo pathway downregulates Drosophila Kib levels independently of Yorkie-mediated transcription. We find that Hpo signaling complex formation promotes Kib degradation via SCFSlimb-mediated ubiquitination, that this effect requires Merlin, Salvador, Hpo, and Warts, and that this mechanism functions independently of other upstream Hpo pathway activators. Moreover, Kib degradation appears patterned by differences in mechanical tension across the wing. We propose that Kib degradation mediated by Hpo pathway components and regulated by cytoskeletal tension serves to control Kib-driven Hpo pathway activation and ensure optimally scaled and patterned tissue growth.
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Affiliation(s)
- Sherzod A Tokamov
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States.,Committee on Development, Regeneration and Stem Cell Biology, The University of Chicago, Chicago, United States
| | - Ting Su
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States
| | - Anne Ullyot
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States
| | - Richard G Fehon
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, United States.,Committee on Development, Regeneration and Stem Cell Biology, The University of Chicago, Chicago, United States
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11
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Yee WB, Delaney PM, Vanderzalm PJ, Ramachandran S, Fehon RG. The CAF-1 complex couples Hippo pathway target gene expression and DNA replication. Mol Biol Cell 2019; 30:2929-2942. [PMID: 31553691 PMCID: PMC6822585 DOI: 10.1091/mbc.e19-07-0387] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The Hippo signaling pathway regulates tissue growth and organ development in many animals, including humans. Pathway activity leads to inactivation of Yorkie (Yki), a transcriptional coactivator that drives expression of growth-promoting genes. In addition, Yki has been shown to recruit chromatin modifiers that enhance chromatin accessibility and thereby enhance Yki function. Here, we asked whether changes in chromatin accessibility that occur during DNA replication could also affect Yki function. We found that depletion of the chromatin assembly complex-1 (CAF-1) complex, a histone chaperone that is required for nucleosome assembly after DNA replication, in the wing imaginal epithelium leads to increased Hippo pathway target gene expression but does not affect expression of other genes. Yki shows greater association with target sites when CAF-1 is depleted and misregulation of target gene expression is Yki-dependent, suggesting that nucleosome assembly competes with Yki for pathway targets post-DNA replication. Consistent with this idea, increased target gene expression is DNA replication dependent and newly replicated chromatin at target sites shows marked nucleosome depletion when CAF-1 function is reduced. These observations suggest a connection between cell cycle progression and Hippo pathway target expression, providing insights into functions of the Hippo pathway in normal and abnormal tissue growth.
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Affiliation(s)
- William B Yee
- Department of Molecular Genetics and Cell Biology.,Graduate Program in Cell and Molecular Biology, and
| | | | - Pamela J Vanderzalm
- Department of Molecular Genetics and Cell Biology.,Department of Biology, John Carroll University, University Heights, OH 44118
| | - Srinivas Ramachandran
- RNA Bioscience Initiative and.,Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045
| | - Richard G Fehon
- Department of Molecular Genetics and Cell Biology.,Graduate Program in Cell and Molecular Biology, and
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12
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Hughes SC, Simmonds AJ. Drosophila mRNA Localization During Later Development: Past, Present, and Future. Front Genet 2019; 10:135. [PMID: 30899273 PMCID: PMC6416162 DOI: 10.3389/fgene.2019.00135] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 02/11/2019] [Indexed: 12/12/2022] Open
Abstract
Multiple mechanisms tightly regulate mRNAs during their transcription, translation, and degradation. Of these, the physical localization of mRNAs to specific cytoplasmic regions is relatively easy to detect; however, linking localization to functional regulatory roles has been more difficult to establish. Historically, Drosophila melanogaster is a highly effective model to identify localized mRNAs and has helped identify roles for this process by regulating various cell activities. The majority of the well-characterized functional roles for localizing mRNAs to sub-regions of the cytoplasm have come from the Drosophila oocyte and early syncytial embryo. At present, relatively few functional roles have been established for mRNA localization within the relatively smaller, differentiated somatic cell lineages characteristic of later development, beginning with the cellular blastoderm, and the multiple cell lineages that make up the gastrulating embryo, larva, and adult. This review is divided into three parts—the first outlines past evidence for cytoplasmic mRNA localization affecting aspects of cellular activity post-blastoderm development in Drosophila. The majority of these known examples come from highly polarized cell lineages such as differentiating neurons. The second part considers the present state of affairs where we now know that many, if not most mRNAs are localized to discrete cytoplasmic regions in one or more somatic cell lineages of cellularized embryos, larvae or adults. Assuming that the phenomenon of cytoplasmic mRNA localization represents an underlying functional activity, and correlation with the encoded proteins suggests that mRNA localization is involved in far more than neuronal differentiation. Thus, it seems highly likely that past-identified examples represent only a small fraction of localization-based mRNA regulation in somatic cells. The last part highlights recent technological advances that now provide an opportunity for probing the role of mRNA localization in Drosophila, moving beyond cataloging the diversity of localized mRNAs to a similar understanding of how localization affects mRNA activity.
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Affiliation(s)
- Sarah C Hughes
- Department of Medical Genetics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada.,Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Andrew J Simmonds
- Department of Cell Biology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
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13
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Abstract
Organ growth is fundamental to animal development. One of major mechanisms for growth control is mediated by the conserved Hippo signaling pathway initially identified in Drosophila. The core of this pathway in Drosophila consists of a cascade of protein kinases Hippo and Warts that negatively regulate transcriptional coactivator Yorkie (Yki). Activation of Yki promotes cell survival and proliferation to induce organ growth. A key issue in Hippo signaling is to understand how core kinase cascade is activated. Activation of Hippo kinase cascade is regulated in the upstream by at least two transmembrane proteins Crumbs and Fat that act in parallel. These membrane proteins interact with additional factors such as FERM-domain proteins Expanded and Merlin to modulate subcellular localization and function of the Hippo kinase cascade. Hippo signaling is also influenced by cytoskeletal networks and cell tension in epithelia of developing organs. These upstream events in the regulation of Hippo signaling are only partially understood. This review focuses on our current understanding of some upstream processes involved in Hippo signaling in developing Drosophila organs.
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Affiliation(s)
- Kwang-Wook Choi
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
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14
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Lipid binding promotes the open conformation and tumor-suppressive activity of neurofibromin 2. Nat Commun 2018; 9:1338. [PMID: 29626191 PMCID: PMC5889391 DOI: 10.1038/s41467-018-03648-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 03/02/2018] [Indexed: 01/29/2023] Open
Abstract
Neurofibromatosis type 2 (NF2) is a tumor-forming disease of the nervous system caused by deletion or by loss-of-function mutations in NF2, encoding the tumor suppressing protein neurofibromin 2 (also known as schwannomin or merlin). Neurofibromin 2 is a member of the ezrin, radixin, moesin (ERM) family of proteins regulating the cytoskeleton and cell signaling. The correlation of the tumor-suppressive function and conformation (open or closed) of neurofibromin 2 has been subject to much speculation, often based on extrapolation from other ERM proteins, and controversy. Here we show that lipid binding results in the open conformation of neurofibromin 2 and that lipid binding is necessary for inhibiting cell proliferation. Collectively, our results provide a mechanism in which the open conformation is unambiguously correlated with lipid binding and localization to the membrane, which are critical for the tumor-suppressive function of neurofibromin 2, thus finally reconciling the long-standing conformation and function debate. Neurofibromin 2 (NF2) is a tumour suppressor that inhibits cell growth. Here the authors combine functional, biochemical, and structural studies and show that lipid-bound NF2 adopts an open conformation and that NF2 lipid binding is required for inhibition of cell proliferation.
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15
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NF2/Merlin Inactivation and Potential Therapeutic Targets in Mesothelioma. Int J Mol Sci 2018; 19:ijms19040988. [PMID: 29587439 PMCID: PMC5979333 DOI: 10.3390/ijms19040988] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 03/19/2018] [Accepted: 03/19/2018] [Indexed: 12/14/2022] Open
Abstract
The neurofibromatosis type 2 (NF2) gene encodes merlin, a tumor suppressor protein frequently inactivated in schwannoma, meningioma, and malignant mesothelioma (MM). The sequence of merlin is similar to that of ezrin/radixin/moesin (ERM) proteins which crosslink actin with the plasma membrane, suggesting that merlin plays a role in transducing extracellular signals to the actin cytoskeleton. Merlin adopts a distinct closed conformation defined by specific intramolecular interactions and regulates diverse cellular events such as transcription, translation, ubiquitination, and miRNA biosynthesis, many of which are mediated through Hippo and mTOR signaling, which are known to be closely involved in cancer development. MM is a very aggressive tumor associated with asbestos exposure, and genetic alterations in NF2 that abrogate merlin’s functional activity are found in about 40% of MMs, indicating the importance of NF2 inactivation in MM development and progression. In this review, we summarize the current knowledge of molecular events triggered by NF2/merlin inactivation, which lead to the development of mesothelioma and other cancers, and discuss potential therapeutic targets in merlin-deficient mesotheliomas.
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16
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Tsai CR, Anderson AE, Burra S, Jo J, Galko MJ. Yorkie regulates epidermal wound healing in Drosophila larvae independently of cell proliferation and apoptosis. Dev Biol 2017; 427:61-71. [PMID: 28514643 DOI: 10.1016/j.ydbio.2017.05.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 05/01/2017] [Accepted: 05/09/2017] [Indexed: 12/19/2022]
Abstract
Yorkie (Yki), the transcriptional co-activator of the Hippo signaling pathway, has well-characterized roles in balancing apoptosis and cell division during organ growth control. Yki is also required in diverse tissue regenerative contexts. In most cases this requirement reflects its well-characterized roles in balancing apoptosis and cell division. Whether Yki has repair functions outside of the control of cell proliferation, death, and growth is not clear. Here we show that Yki and Scalloped (Sd) are required for epidermal wound closure in the Drosophila larval epidermis. Using a GFP-tagged Yki transgene we show that Yki transiently translocates to some epidermal nuclei upon wounding. Genetic analysis strongly suggests that Yki interacts with the known wound healing pathway, Jun N-terminal kinase (JNK), but not with Platelet Derived Growth Factor/Vascular-Endothelial Growth Factor receptor (Pvr). Yki likely acts downstream of or parallel to JNK signaling and does not appear to regulate either proliferation or apoptosis in the larval epidermis during wound repair. Analysis of actin structures after wounding suggests that Yki and Sd promote wound closure through actin regulation. In sum, we found that Yki regulates an epithelial tissue repair process independently of its previously documented roles in balancing proliferation and apoptosis.
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Affiliation(s)
- Chang-Ru Tsai
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Aimee E Anderson
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sirisha Burra
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Juyeon Jo
- Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Genes and Development Graduate Program, Graduate School of Biomedical Sciences, The University of Texas M.D. Anderson Cancer Center, TX 77030, USA
| | - Michael J Galko
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; Genes and Development Graduate Program, Graduate School of Biomedical Sciences, The University of Texas M.D. Anderson Cancer Center, TX 77030, USA.
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17
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Cairns L, Tran T, Kavran JM. Structural Insights into the Regulation of Hippo Signaling. ACS Chem Biol 2017; 12:601-610. [PMID: 28150487 DOI: 10.1021/acschembio.6b01058] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
During development, the Hippo pathway regulates the balance between cell proliferation and apoptosis to control organ size. Appropriate Hippo signaling is associated with stem cell maintenance, while inappropriate signaling can result in tumorigenesis and cancer. Cellular and genetic investigations have identified core components and determined that complex formation and protein phosphorylation are crucial regulatory events. The recent spate of high-resolution structures of Hippo pathway components have begun to reveal the molecular mechanisms controlling these events, including the molecular determinates of complex formation between YAP and TEAD, the role of phosphorylation in controlling complex formation by Mob, and the conformational changes accompanying Mst1/2 kinase domain activation. We will review these advances and revisit previous structures to provide a comprehensive overview of the structural changes associated with the regulation of this pathway as well as discuss areas that could benefit from further mechanistic studies.
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Affiliation(s)
- Leah Cairns
- Department
of Biochemistry and Molecular Biology, Bloomberg School
of Public Health and ‡Department of Biophysics and Biophysical Chemistry, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205, United States
| | - Thao Tran
- Department
of Biochemistry and Molecular Biology, Bloomberg School
of Public Health and ‡Department of Biophysics and Biophysical Chemistry, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205, United States
| | - Jennifer M. Kavran
- Department
of Biochemistry and Molecular Biology, Bloomberg School
of Public Health and ‡Department of Biophysics and Biophysical Chemistry, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205, United States
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18
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Matsuda T, Zhai P, Sciarretta S, Zhang Y, Jeong JI, Ikeda S, Park J, Hsu CP, Tian B, Pan D, Sadoshima J, Del Re DP. NF2 Activates Hippo Signaling and Promotes Ischemia/Reperfusion Injury in the Heart. Circ Res 2016; 119:596-606. [PMID: 27402866 DOI: 10.1161/circresaha.116.308586] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 07/08/2016] [Indexed: 01/07/2023]
Abstract
RATIONALE NF2 (neurofibromin 2) is an established tumor suppressor that promotes apoptosis and inhibits growth in a variety of cell types, yet its function in cardiomyocytes remains largely unknown. OBJECTIVE We sought to determine the role of NF2 in cardiomyocyte apoptosis and ischemia/reperfusion (I/R) injury in the heart. METHODS AND RESULTS We investigated the function of NF2 in isolated cardiomyocytes and mouse myocardium at baseline and in response to oxidative stress. NF2 was activated in cardiomyocytes subjected to H2O2 and in murine hearts subjected to I/R. Increased NF2 expression promoted the activation of Mst1 (mammalian sterile 20-like kinase 1) and the inhibition of Yap (Yes-associated protein), whereas knockdown of NF2 attenuated these responses after oxidative stress. NF2 increased the apoptosis of cardiomyocytes that appeared dependent on Mst1 activity. Mice deficient for NF2 in cardiomyocytes, NF2 cardiomyocyte-specific knockout (CKO), were protected against global I/R ex vivo and showed improved cardiac functional recovery. Moreover, NF2 cardiomyocyte-specific knockout mice were protected against I/R injury in vivo and showed the upregulation of Yap target gene expression. Mechanistically, we observed nuclear association between NF2 and its activator MYPT-1 (myosin phosphatase target subunit 1) in cardiomyocytes, and a subpopulation of stress-induced nuclear Mst1 was diminished in NF2 CKO hearts. Finally, mice deficient for both NF2 and Yap failed to show protection against I/R indicating that Yap is an important target of NF2 in the adult heart. CONCLUSIONS NF2 is activated by oxidative stress in cardiomyocytes and mouse myocardium and facilitates apoptosis. NF2 promotes I/R injury through the activation of Mst1 and inhibition of Yap, thereby regulating Hippo signaling in the adult heart.
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Affiliation(s)
- Takahisa Matsuda
- From the Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers, New Jersey Medical School, Newark (T.M., P.Z., Y.Z., J.I.J., S.I., J.S., D.P.D.R.); Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, New Jersey Medical School, Newark (J.P., B.T.); Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli (IS) (S.S.) and the Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy (S.S.); Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taiwan (C.-P.H.); and Howard Hughes Medical Institute and Department of Physiology, UT Southwestern Medical Center, Dallas, TX (D.P.)
| | - Peiyong Zhai
- From the Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers, New Jersey Medical School, Newark (T.M., P.Z., Y.Z., J.I.J., S.I., J.S., D.P.D.R.); Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, New Jersey Medical School, Newark (J.P., B.T.); Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli (IS) (S.S.) and the Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy (S.S.); Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taiwan (C.-P.H.); and Howard Hughes Medical Institute and Department of Physiology, UT Southwestern Medical Center, Dallas, TX (D.P.)
| | - Sebastiano Sciarretta
- From the Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers, New Jersey Medical School, Newark (T.M., P.Z., Y.Z., J.I.J., S.I., J.S., D.P.D.R.); Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, New Jersey Medical School, Newark (J.P., B.T.); Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli (IS) (S.S.) and the Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy (S.S.); Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taiwan (C.-P.H.); and Howard Hughes Medical Institute and Department of Physiology, UT Southwestern Medical Center, Dallas, TX (D.P.)
| | - Yu Zhang
- From the Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers, New Jersey Medical School, Newark (T.M., P.Z., Y.Z., J.I.J., S.I., J.S., D.P.D.R.); Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, New Jersey Medical School, Newark (J.P., B.T.); Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli (IS) (S.S.) and the Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy (S.S.); Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taiwan (C.-P.H.); and Howard Hughes Medical Institute and Department of Physiology, UT Southwestern Medical Center, Dallas, TX (D.P.)
| | - Jae Im Jeong
- From the Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers, New Jersey Medical School, Newark (T.M., P.Z., Y.Z., J.I.J., S.I., J.S., D.P.D.R.); Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, New Jersey Medical School, Newark (J.P., B.T.); Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli (IS) (S.S.) and the Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy (S.S.); Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taiwan (C.-P.H.); and Howard Hughes Medical Institute and Department of Physiology, UT Southwestern Medical Center, Dallas, TX (D.P.)
| | - Shohei Ikeda
- From the Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers, New Jersey Medical School, Newark (T.M., P.Z., Y.Z., J.I.J., S.I., J.S., D.P.D.R.); Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, New Jersey Medical School, Newark (J.P., B.T.); Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli (IS) (S.S.) and the Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy (S.S.); Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taiwan (C.-P.H.); and Howard Hughes Medical Institute and Department of Physiology, UT Southwestern Medical Center, Dallas, TX (D.P.)
| | - Jiyeon Park
- From the Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers, New Jersey Medical School, Newark (T.M., P.Z., Y.Z., J.I.J., S.I., J.S., D.P.D.R.); Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, New Jersey Medical School, Newark (J.P., B.T.); Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli (IS) (S.S.) and the Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy (S.S.); Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taiwan (C.-P.H.); and Howard Hughes Medical Institute and Department of Physiology, UT Southwestern Medical Center, Dallas, TX (D.P.)
| | - Chiao-Po Hsu
- From the Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers, New Jersey Medical School, Newark (T.M., P.Z., Y.Z., J.I.J., S.I., J.S., D.P.D.R.); Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, New Jersey Medical School, Newark (J.P., B.T.); Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli (IS) (S.S.) and the Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy (S.S.); Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taiwan (C.-P.H.); and Howard Hughes Medical Institute and Department of Physiology, UT Southwestern Medical Center, Dallas, TX (D.P.)
| | - Bin Tian
- From the Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers, New Jersey Medical School, Newark (T.M., P.Z., Y.Z., J.I.J., S.I., J.S., D.P.D.R.); Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, New Jersey Medical School, Newark (J.P., B.T.); Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli (IS) (S.S.) and the Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy (S.S.); Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taiwan (C.-P.H.); and Howard Hughes Medical Institute and Department of Physiology, UT Southwestern Medical Center, Dallas, TX (D.P.)
| | - Duojia Pan
- From the Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers, New Jersey Medical School, Newark (T.M., P.Z., Y.Z., J.I.J., S.I., J.S., D.P.D.R.); Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, New Jersey Medical School, Newark (J.P., B.T.); Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli (IS) (S.S.) and the Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy (S.S.); Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taiwan (C.-P.H.); and Howard Hughes Medical Institute and Department of Physiology, UT Southwestern Medical Center, Dallas, TX (D.P.)
| | - Junichi Sadoshima
- From the Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers, New Jersey Medical School, Newark (T.M., P.Z., Y.Z., J.I.J., S.I., J.S., D.P.D.R.); Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, New Jersey Medical School, Newark (J.P., B.T.); Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli (IS) (S.S.) and the Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy (S.S.); Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taiwan (C.-P.H.); and Howard Hughes Medical Institute and Department of Physiology, UT Southwestern Medical Center, Dallas, TX (D.P.)
| | - Dominic P Del Re
- From the Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers, New Jersey Medical School, Newark (T.M., P.Z., Y.Z., J.I.J., S.I., J.S., D.P.D.R.); Department of Microbiology, Biochemistry, and Molecular Genetics, Rutgers, New Jersey Medical School, Newark (J.P., B.T.); Department of AngioCardioNeurology, IRCCS Neuromed, Pozzilli (IS) (S.S.) and the Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Latina, Italy (S.S.); Department of Surgery, Taipei Veterans General Hospital, National Yang-Ming University School of Medicine, Taiwan (C.-P.H.); and Howard Hughes Medical Institute and Department of Physiology, UT Southwestern Medical Center, Dallas, TX (D.P.).
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Hu L, Xu J, Yin MX, Zhang L, Lu Y, Wu W, Xue Z, Ho MS, Gao G, Zhao Y, Zhang L. Ack promotes tissue growth via phosphorylation and suppression of the Hippo pathway component Expanded. Cell Discov 2016; 2:15047. [PMID: 27462444 PMCID: PMC4860957 DOI: 10.1038/celldisc.2015.47] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 12/01/2015] [Indexed: 12/11/2022] Open
Abstract
Non-receptor tyrosine kinase activated cdc42 kinase was reported to participate in several types of cancers in mammals. It is also believed to have an anti-apoptotic function in Drosophila. Here, we report the identification of Drosophila activated cdc42 kinase as a growth promoter and a novel Hippo signaling pathway regulator. We find that activated cdc42 kinase promotes tissue growth through modulating Yorkie activity. Furthermore, we demonstrate that activated cdc42 kinase interacts with Expanded and induces tyrosine phosphorylation of Expanded on multiple sites. We propose a model that activated cdc42 kinase negatively regulates Expanded by changing its phosphorylation status to promote tissue growth. Moreover, we show that ack genetically interacts with merlin and expanded. Thus, we identify Drosophila activated cdc42 kinase as a Hippo pathway regulator.
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Affiliation(s)
- Lianxin Hu
- State Key Laboratory of Cell Biology, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai, China
| | - Jiajun Xu
- State Key Laboratory of Cell Biology, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai, China
| | - Meng-Xin Yin
- State Key Laboratory of Cell Biology, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai, China
| | - Liguo Zhang
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign , Urbana, IL, USA
| | - Yi Lu
- State Key Laboratory of Cell Biology, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai, China
| | - Wenqing Wu
- State Key Laboratory of Cell Biology, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai, China
| | - Zhaoyu Xue
- School of Life Sciences, Tsinghua University , Beijing, China
| | - Margaret S Ho
- Department of Anatomy and Neurobiology, School of Medicine, Tongji University , Shanghai, China
| | - Guanjun Gao
- School of Life Sciences, Tsinghua University , Beijing, China
| | - Yun Zhao
- State Key Laboratory of Cell Biology, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Lei Zhang
- State Key Laboratory of Cell Biology, Innovation Center for Cell Signaling Network, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; School of Life Science and Technology, ShanghaiTech University, Shanghai, China
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20
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Role of cyclins D1 and D3 in vestibular schwannoma. The Journal of Laryngology & Otology 2015; 130 Suppl 1:S2-10. [PMID: 26165351 DOI: 10.1017/s0022215115001735] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Vestibular schwannomas in younger patients have been observed to be larger in size and grow more quickly. OBJECTIVE This study aimed to evaluate the expression of three important cell cycle proteins, cyclin D1, cyclin D3 and Ki-67, in vestibular schwannoma patients separated into two age groups: ≤ 40 years or > 40 years. METHOD Immunohistochemical detection of cyclin D1, cyclin D3 and Ki-67 was undertaken in 180 surgically resected vestibular schwannomas. RESULTS The proliferation index of vestibular schwannomas was statistically higher in the ≤ 40 years age group compared to that in the > 40 years age group (mean of 4.52 vs 3.27, respectively; p = 0.01). Overexpression of cyclin D1 and cyclin D3 was found in 68 per cent and 44 per cent of tumours, respectively. CONCLUSION There was an increased Ki-67 proliferation index in the younger age group that appears to correlate with clinical behaviour. Vestibular schwannomas in both age groups show increased expression of cyclin D1 and cyclin D3.
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21
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Panneton V, Nath A, Sader F, Delaunay N, Pelletier A, Maier D, Oh K, Hipfner DR. Regulation of Catalytic and Non-catalytic Functions of the Drosophila Ste20 Kinase Slik by Activation Segment Phosphorylation. J Biol Chem 2015; 290:20960-20971. [PMID: 26170449 DOI: 10.1074/jbc.m115.645952] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Indexed: 01/21/2023] Open
Abstract
Protein kinases carry out important functions in cells both by phosphorylating substrates and by means of regulated non-catalytic activities. Such non-catalytic functions have been ascribed to many kinases, including some members of the Ste20 family. The Drosophila Ste20 kinase Slik phosphorylates and activates Moesin in developing epithelial tissues to promote epithelial tissue integrity. It also functions non-catalytically to promote epithelial cell proliferation and tissue growth. We carried out a structure-function analysis to determine how these two distinct activities of Slik are controlled. We find that the conserved C-terminal coiled-coil domain of Slik, which is necessary and sufficient for apical localization of the kinase in epithelial cells, is not required for Moesin phosphorylation but is critical for the growth-promoting function of Slik. Slik is auto- and trans-phosphorylated in vivo. Phosphorylation of at least two of three conserved sites in the activation segment is required for both efficient catalytic activity and non-catalytic signaling. Slik function is thus dependent upon proper localization of the kinase via the C-terminal coiled-coil domain and activation via activation segment phosphorylation, which enhances both phosphorylation of substrates like Moesin and engagement of effectors of its non-catalytic growth-promoting activity.
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Affiliation(s)
- Vincent Panneton
- Institut de Recherches Cliniques de Montréal, Montreal, Quebec H2W 1R7, Canada; Molecular Biology Program, Université de Montréal, Montreal, Quebec H3T 3J7, Canada
| | - Apurba Nath
- Institut de Recherches Cliniques de Montréal, Montreal, Quebec H2W 1R7, Canada; Molecular Biology Program, Université de Montréal, Montreal, Quebec H3T 3J7, Canada
| | - Fadi Sader
- Institut de Recherches Cliniques de Montréal, Montreal, Quebec H2W 1R7, Canada
| | - Nathalie Delaunay
- Institut de Recherches Cliniques de Montréal, Montreal, Quebec H2W 1R7, Canada
| | - Ariane Pelletier
- Institut de Recherches Cliniques de Montréal, Montreal, Quebec H2W 1R7, Canada
| | - Dominic Maier
- Institut de Recherches Cliniques de Montréal, Montreal, Quebec H2W 1R7, Canada; Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 2B2, Canada
| | - Karen Oh
- Institut de Recherches Cliniques de Montréal, Montreal, Quebec H2W 1R7, Canada
| | - David R Hipfner
- Institut de Recherches Cliniques de Montréal, Montreal, Quebec H2W 1R7, Canada; Molecular Biology Program, Université de Montréal, Montreal, Quebec H3T 3J7, Canada; Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec H3A 2B2, Canada; Department of Medicine, Université de Montréal, Montreal, Quebec H3C 3J7, Canada.
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22
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Li Y, Zhou H, Li F, Chan SW, Lin Z, Wei Z, Yang Z, Guo F, Lim CJ, Xing W, Shen Y, Hong W, Long J, Zhang M. Angiomotin binding-induced activation of Merlin/NF2 in the Hippo pathway. Cell Res 2015; 25:801-17. [PMID: 26045165 PMCID: PMC4493278 DOI: 10.1038/cr.2015.69] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Revised: 05/08/2015] [Accepted: 05/11/2015] [Indexed: 12/18/2022] Open
Abstract
The tumor suppressor Merlin/NF2 functions upstream of the core Hippo pathway kinases Lats1/2 and Mst1/2, as well as the nuclear E3 ubiquitin ligase CRL4(DCAF1). Numerous mutations of Merlin have been identified in Neurofibromatosis type 2 and other cancer patients. Despite more than two decades of research, the upstream regulator of Merlin in the Hippo pathway remains unknown. Here we show by high-resolution crystal structures that the Lats1/2-binding site on the Merlin FERM domain is physically blocked by Merlin's auto-inhibitory tail. Angiomotin binding releases the auto-inhibition and promotes Merlin's binding to Lats1/2. Phosphorylation of Ser518 outside the Merlin's auto-inhibitory tail does not obviously alter Merlin's conformation, but instead prevents angiomotin from binding and thus inhibits Hippo pathway kinase activation. Cancer-causing mutations clustered in the angiomotin-binding domain impair angiomotin-mediated Merlin activation. Our findings reveal that angiomotin and Merlin respectively interface cortical actin filaments and core kinases in Hippo signaling, and allow construction of a complete Hippo signaling pathway.
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Affiliation(s)
- Youjun Li
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong, China
| | - Hao Zhou
- 1] State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin 300071, China [2] College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Fengzhi Li
- 1] State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin 300071, China [2] College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Siew Wee Chan
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), 61, Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Zhijie Lin
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong, China
| | - Zhiyi Wei
- 1] Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong, China [2] Department of Biology, South University of Science and Technology of China, Shenzhen, Guangdong 518055, China
| | - Zhou Yang
- Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong, China
| | - Fusheng Guo
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), 61, Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Chun Jye Lim
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), 61, Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Wancai Xing
- 1] State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin 300071, China [2] College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Yuequan Shen
- 1] State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin 300071, China [2] College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Wanjin Hong
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), 61, Biopolis Drive, Proteos, Singapore 138673, Singapore
| | - Jiafu Long
- 1] State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, Tianjin 300071, China [2] College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Mingjie Zhang
- 1] Division of Life Science, State Key Laboratory of Molecular Neuroscience, Hong Kong, China [2] Center of Systems Biology and Human Health, School of Science and Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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23
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Hong L, Cai Y, Jiang M, Zhou D, Chen L. The Hippo signaling pathway in liver regeneration and tumorigenesis. Acta Biochim Biophys Sin (Shanghai) 2015; 47:46-52. [PMID: 25476204 DOI: 10.1093/abbs/gmu106] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Hippo signaling pathway is an evolutionarily conserved signaling module that plays critical roles in liver size control and tumorigenesis. The Hippo pathway consists of a core kinase cascade in which the mammalian Ste20-like kinases (Mst1/2, orthologs of Drosophila Hippo) and their cofactor Salvador (Sav1) form a complex to phosphorylate and activate the large tumor suppressor (Lats1/2). Lats1/2 kinases in turn phosphorylate and inhibit the transcription co-activators, the Yes-associated protein (YAP) and the transcriptional co-activator with PDZ-binding motif (TAZ), two major downstream effectors of the Hippo pathway. Losses of the Hippo pathway components induce aberrant hepatomegaly and tumorigenesis, in which YAP coordinates regulation of cell proliferation and apoptosis and plays an essential role. This review summarizes the current findings of the regulation of Hippo signaling in liver regeneration and tumorigenesis, focusing on how the loss of tumor suppressor components of the Hippo pathway results in liver cancers and discussing the molecular mechanisms that regulate the expression and activation of its downstream effector YAP in liver tumorigenesis.
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Affiliation(s)
- Lixin Hong
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Biology, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Yabo Cai
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Biology, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Mingting Jiang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Biology, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Dawang Zhou
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Biology, School of Life Sciences, Xiamen University, Xiamen 361102, China
| | - Lanfen Chen
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Biology, School of Life Sciences, Xiamen University, Xiamen 361102, China
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24
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Abeysundara N, Leung AC, Primrose DA, Hughes SC. Regulation of cell proliferation and adhesion by means of a novel region of drosophila merlin interacting with Sip1. Dev Dyn 2014; 243:1554-70. [DOI: 10.1002/dvdy.24187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 08/08/2014] [Accepted: 09/03/2014] [Indexed: 01/22/2023] Open
Affiliation(s)
- Namal Abeysundara
- Department of Medical Genetics; University of Alberta; Edmonton Alberta Canada
| | - Albert C. Leung
- Department of Medical Genetics; University of Alberta; Edmonton Alberta Canada
| | - David A. Primrose
- Department of Medical Genetics; University of Alberta; Edmonton Alberta Canada
| | - Sarah C. Hughes
- Department of Medical Genetics; University of Alberta; Edmonton Alberta Canada
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25
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Garcia C, Gutmann DH. Using the neurofibromatosis tumor predisposition syndromes to understand normal nervous system development. SCIENTIFICA 2014; 2014:915725. [PMID: 25243094 PMCID: PMC4163293 DOI: 10.1155/2014/915725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 05/07/2014] [Indexed: 06/03/2023]
Abstract
Development is a tightly regulated process that involves stem cell self-renewal, differentiation, cell-to-cell communication, apoptosis, and blood vessel formation. These coordinated processes ensure that tissues maintain a size and architecture that is appropriate for normal tissue function. As such, tumors arise when cells acquire genetic mutations that allow them to escape the normal growth constraints. In this regard, the study of tumor predisposition syndromes affords a unique platform to better understand normal development and the process by which normal cells transform into cancers. Herein, we review the processes governing normal brain development, discuss how brain cancer represents a disruption of these normal processes, and highlight insights into both normal development and cancer made possible by the study of tumor predisposition syndromes.
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Affiliation(s)
- Cynthia Garcia
- Department of Neurology, Washington University School of Medicine, Box 8111, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - David H. Gutmann
- Department of Neurology, Washington University School of Medicine, Box 8111, 660 South Euclid Avenue, St. Louis, MO 63110, USA
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26
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Molecular insights into NF2/Merlin tumor suppressor function. FEBS Lett 2014; 588:2743-52. [PMID: 24726726 DOI: 10.1016/j.febslet.2014.04.001] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/01/2014] [Accepted: 04/02/2014] [Indexed: 02/07/2023]
Abstract
The FERM domain protein Merlin, encoded by the NF2 tumor suppressor gene, regulates cell proliferation in response to adhesive signaling. The growth inhibitory function of Merlin is induced by intercellular adhesion and inactivated by joint integrin/receptor tyrosine kinase signaling. Merlin contributes to the formation of cell junctions in polarized tissues, activates anti-mitogenic signaling at tight-junctions, and inhibits oncogenic gene expression. Thus, inactivation of Merlin causes uncontrolled mitogenic signaling and tumorigenesis. Merlin's predominant tumor suppressive functions are attributable to its control of oncogenic gene expression through regulation of Hippo signaling. Notably, Merlin translocates to the nucleus where it directly inhibits the CRL4(DCAF1) E3 ubiquitin ligase, thereby suppressing inhibition of the Lats kinases. A dichotomy in NF2 function has emerged whereby Merlin acts at the cell cortex to organize cell junctions and propagate anti-mitogenic signaling, whereas it inhibits oncogenic gene expression through the inhibition of CRL4(DCAF1) and activation of Hippo signaling. The biochemical events underlying Merlin's normal function and tumor suppressive activity will be discussed in this Review, with emphasis on recent discoveries that have greatly influenced our understanding of Merlin biology.
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27
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Gavilan HS, Kulikauskas RM, Gutmann DH, Fehon RG. In vivo functional analysis of the human NF2 tumor suppressor gene in Drosophila. PLoS One 2014; 9:e90853. [PMID: 24595234 PMCID: PMC3942481 DOI: 10.1371/journal.pone.0090853] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 02/04/2014] [Indexed: 11/19/2022] Open
Abstract
The proper control of tissue growth is essential during normal development and an important problem in human disease. Merlin, the product of the Neurofibromatosis 2 tumor suppressor gene, has been extensively studied to understand its functions in growth control. Here we describe experiments in which we used Drosophila as an in vivo system to test the functions of the normal human NF2 gene products and patient-derived mutant alleles. Although the predominant NF2 gene isoform, isoform 1, could functionally replace the Drosophila Merlin gene, a second isoform with a distinct C-terminal tail could not. Immunofluorescence studies show that the two isoforms have distinct subcellular localizations when expressed in the polarized imaginal epithelium, and function in genetic rescue assays correlates with apical localization of the NF2 protein. Interestingly, we found that a patient-derived missense allele, NF2L64P, appears to be temperature sensitive. These studies highlight the utility of Drosophila for in vivo functional analysis of highly conserved human disease genes.
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Affiliation(s)
- Heather S. Gavilan
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - Rima M. Kulikauskas
- Department of Biology, Duke University, Durham, North Carolina, United States of America
| | - David H. Gutmann
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Richard G. Fehon
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois, United States of America
- * E-mail:
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28
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Spatial organization of Hippo signaling at the plasma membrane mediated by the tumor suppressor Merlin/NF2. Cell 2013; 154:1342-55. [PMID: 24012335 DOI: 10.1016/j.cell.2013.08.025] [Citation(s) in RCA: 402] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 06/26/2013] [Accepted: 08/15/2013] [Indexed: 12/22/2022]
Abstract
Although Merlin/NF2 was discovered two decades ago as a tumor suppressor underlying Neurofibromatosis type II, its precise molecular mechanism remains poorly understood. Recent studies in Drosophila revealed a potential link between Merlin and the Hippo pathway by placing Merlin genetically upstream of the kinase Hpo/Mst. In contrast to the commonly depicted linear model of Merlin functioning through Hpo/Mst, here we show that in both Drosophila and mammals, Merlin promotes downstream Hippo signaling without activating the intrinsic kinase activity of Hpo/Mst. Instead, Merlin directly binds and recruits the effector kinase Wts/Lats to the plasma membrane. Membrane recruitment, in turn, promotes Wts phosphorylation by the Hpo-Sav kinase complex. We further show that disruption of the actin cytoskeleton promotes Merlin-Wts interactions, which implicates Merlin in actin-mediated regulation of Hippo signaling. Our findings elucidate an important molecular function of Merlin and highlight the plasma membrane as a critical subcellular compartment for Hippo signal transduction.
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29
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The neuronal transcription factor erect wing regulates specification and maintenance of Drosophila R8 photoreceptor subtypes. Dev Biol 2013; 381:482-90. [PMID: 23850772 DOI: 10.1016/j.ydbio.2013.07.001] [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] [Received: 04/11/2013] [Revised: 06/15/2013] [Accepted: 07/03/2013] [Indexed: 01/27/2023]
Abstract
Signaling pathways are often re-used during development in surprisingly different ways. The Hippo tumor suppressor pathway is best understood for its role in the control of growth. The pathway is also used in a very different context, in the Drosophila eye for the robust specification of R8 photoreceptor neuron subtypes, which complete their terminal differentiation by expressing light-sensing Rhodopsin (Rh) proteins. A double negative feedback loop between the Warts kinase of the Hippo pathway and the PH-domain growth regulator Melted regulates the choice between 'pale' R8 (pR8) fate defined by Rh5 expression and 'yellow' R8 (yR8) fate characterized by Rh6 expression. Here, we show that the gene encoding the homolog of human Nuclear respiratory factor 1, erect wing (ewg), is autonomously required to inhibit warts expression and to promote melted expression to specify pR8 subtype fate and induce Rh5. ewg mutants express Rh6 in most R8s due to ectopic warts expression. Further, ewg is continuously required to maintain repression of Rh6 in pR8s in aging flies. Our work shows that Ewg is a critical factor for the stable down-regulation of Hippo pathway activity to determine neuronal subtype fates. Neural-enriched factors, such as Ewg, may generally contribute to the contextual re-use of signaling pathways in post-mitotic neurons.
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30
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Cockburn K, Biechele S, Garner J, Rossant J. The Hippo pathway member Nf2 is required for inner cell mass specification. Curr Biol 2013; 23:1195-201. [PMID: 23791728 DOI: 10.1016/j.cub.2013.05.044] [Citation(s) in RCA: 162] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Revised: 05/18/2013] [Accepted: 05/22/2013] [Indexed: 02/03/2023]
Abstract
During mammalian development, the first two lineages to be specified are the trophectoderm (TE) and the inner cell mass (ICM). The Hippo pathway kinases Lats 1 and 2 (Lats1/2) and the transcriptional coactivator Yap play important roles in this specification process [1]. In outside cells of the embryo, Yap is nuclear localized and cooperates with Tead4 to induce the TE-specifying transcription factor Cdx2. In inside cells, Lats1/2 phosphorylate Yap and prevent its nuclear localization. The factors acting upstream of Lats1/2 and Yap in this context have not been identified. Here, we demonstrate that the upstream Hippo pathway member Nf2/Merlin is required for Lats1/2-dependent Yap phosphorylation in the preimplantation embryo. Injection of dominant-negative Nf2 mRNA causes Yap mislocalization and ectopic Cdx2 expression, effects that can be rescued by overexpression of Lats2 kinase. Zygotic Nf2 mutant blastocysts have mild defects in Yap localization and Cdx2 expression, but these become much more severe upon removal of both maternal and zygotic Nf2. The inside cells of maternal-zygotic mutants fail to establish a pluripotent ICM and form excess TE, resulting in peri-implantation lethality. Together, these data establish a clear role for Nf2 upstream of Yap in the preimplantation embryo and demonstrate that Hippo signaling is essential to segregate the ICM from the TE.
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Affiliation(s)
- Katie Cockburn
- Department of Molecular Genetics, University of Toronto, ON M5S 1A8, Canada
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31
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Strano S, Fausti F, Di Agostino S, Sudol M, Blandino G. PML Surfs into HIPPO Tumor Suppressor Pathway. Front Oncol 2013; 3:36. [PMID: 23459691 PMCID: PMC3585432 DOI: 10.3389/fonc.2013.00036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 02/09/2013] [Indexed: 01/21/2023] Open
Abstract
Growth arrest, inhibition of cell proliferation, apoptosis, senescence, and differentiation are the most characterized effects of a given tumor suppressor response. It is becoming increasingly clear that tumor suppression results from the integrated and synergistic activities of different pathways. This implies that tumor suppression includes linear, as well as lateral, crosstalk signaling. The latter may happen through the concomitant involvement of common nodal proteins. Here, we discuss the role of Promyelocytic leukemia protein (PML) in functional cross-talks with the HIPPO and the p53 family tumor suppressor pathways. PML, in addition to its own anti-tumor activity, contributes to the assembly of an integrated and superior network that may be necessary for the maximization of the tumor suppressor response to diverse oncogenic insults.
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Affiliation(s)
- Sabrina Strano
- Molecular Chemoprevention Group, Molecular Medicine Area, Regina Elena National Cancer Institute Rome, Italy
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32
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Hebert AM, DuBoff B, Casaletto JB, Gladden AB, McClatchey AI. Merlin/ERM proteins establish cortical asymmetry and centrosome position. Genes Dev 2013; 26:2709-23. [PMID: 23249734 DOI: 10.1101/gad.194027.112] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The ability to generate asymmetry at the cell cortex underlies cell polarization and asymmetric cell division. Here we demonstrate a novel role for the tumor suppressor Merlin and closely related ERM proteins (Ezrin, Radixin, and Moesin) in generating cortical asymmetry in the absence of external cues. Our data reveal that Merlin functions to restrict the cortical distribution of the actin regulator Ezrin, which in turn positions the interphase centrosome in single epithelial cells and three-dimensional organotypic cultures. In the absence of Merlin, ectopic cortical Ezrin yields mispositioned centrosomes, misoriented spindles, and aberrant epithelial architecture. Furthermore, in tumor cells with centrosome amplification, the failure to restrict cortical Ezrin abolishes centrosome clustering, yielding multipolar mitoses. These data uncover fundamental roles for Merlin/ERM proteins in spatiotemporally organizing the cell cortex and suggest that Merlin's role in restricting cortical Ezrin may contribute to tumorigenesis by disrupting cell polarity, spindle orientation, and, potentially, genome stability.
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Affiliation(s)
- Alan M Hebert
- Massachusetts General Hospital Center for Cancer Research, Charlestown, Massachusetts 02129, USA
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33
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Laulajainen M, Melikova M, Muranen T, Carpén O, Grönholm M. Distinct overlapping sequences at the carboxy-terminus of merlin regulate its tumour suppressor and morphogenic activity. J Cell Mol Med 2013; 16:2161-75. [PMID: 22325036 PMCID: PMC3822986 DOI: 10.1111/j.1582-4934.2012.01525.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The Neurofibromatosis 2 (NF2) gene product merlin is a tumour suppressor, which in addition to inhibiting cell proliferation regulates cell morphology. The morphogenic properties of merlin may play a role in tumour suppression, as patient-derived tumour cells demonstrate cytoskeletal abnormalities. However, it is still unclear how these functions are linked. The N-terminal FERM-domain of merlin is highly homologous to the oncogenic protein ezrin, while the C-termini are less conserved, suggesting that the opposite effect of the proteins on proliferation could be mediated by their distinct C-terminal regions. In this study we characterize the role of the most C-terminal residues of merlin in the regulation of proliferation, cytoskeletal organization, phosphorylation and intramolecular associations. In addition to the two full-length merlin isoforms and truncating mutations found in patients, we focused on the evolutionally conserved C-terminal residues 545-547, also harbouring disease-causing mutations. We demonstrate that merlin induces cell extensions, which result from impaired retraction of protrusions rather than from increased formation of filopodia. The residues 538-568 were found particularly important for this morphogenic activity. The results further show that both merlin isoforms are able to equally inhibit proliferation, whereas C-terminal mutants affecting residues 545-547 are less effective in growth suppression. This study demonstrates that the C-terminus contains distinct but overlapping functional domains important for regulation of the morphogenic activity, intramolecular associations and cell proliferation.
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Affiliation(s)
- Minja Laulajainen
- Biomedicum Helsinki, Department of Pathology, University of Helsinki, Helsinki, Finland.
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34
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Li W, Cooper J, Karajannis MA, Giancotti FG. Merlin: a tumour suppressor with functions at the cell cortex and in the nucleus. EMBO Rep 2012; 13:204-15. [PMID: 22482125 DOI: 10.1038/embor.2012.11] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Inhibition of proliferation by cell-to-cell contact is essential for tissue organization, and its disruption contributes to tumorigenesis. The FERM domain protein Merlin, encoded by the NF2 tumour suppressor gene, is an important mediator of contact inhibition. Merlin was thought to inhibit mitogenic signalling and activate the Hippo pathway by interacting with diverse target-effectors at or near the plasma membrane. However, recent studies highlight that Merlin pleiotropically affects signalling by migrating into the nucleus and inducing a growth-suppressive programme of gene expression through its direct inhibition of the CRL4DCAF1 E3 ubiquitin ligase. In addition, Merlin promotes the establishment of epithelial adhesion and polarity by recruiting Par3 and aPKC to E-cadherin-dependent junctions, and by ensuring the assembly of tight junctions. These recent advances suggest that Merlin acts at the cell cortex and in the nucleus in a similar, albeit antithetic, manner to the oncogene β-catenin.
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Affiliation(s)
- Wei Li
- Cell Biology Program, Sloan–Kettering Institute for Cancer Research, Memorial Sloan–Kettering Cancer Center, 1275 York Avenue, Box 216, New York, New York 10065, USA
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35
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Hippo and rassf1a Pathways: A Growing Affair. Mol Biol Int 2012; 2012:307628. [PMID: 22830020 PMCID: PMC3399428 DOI: 10.1155/2012/307628] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2012] [Accepted: 05/18/2012] [Indexed: 01/15/2023] Open
Abstract
First discovered in Drosophila, the Hippo pathway regulates the size and shape of organ development. Its discovery and study have helped to address longstanding questions in developmental biology. Central to this pathway is a kinase cascade leading from the tumor suppressor Hippo (Mst1 and Mst2 in mammals) to the Yki protein (YAP and TAZ in mammals), a transcriptional coactivator of target genes involved in cell proliferation, survival, and apoptosis. A dysfunction of the Hippo pathway activity is frequently detected in human cancers. Recent studies have highlighted that the Hippo pathway may play an important role in tissue homoeostasis through the regulation of stem cells, cell differentiation, and tissue regeneration. Recently, the impact of RASSF proteins on Hippo signaling potentiating its proapoptotic activity has been addressed, thus, providing further evidence for Hippo's key role in mammalian tumorigenesis as well as other important diseases.
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36
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37
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Thomson TC, Schneemann A, Johnson J. Oocyte destruction is activated during viral infection. Genesis 2012; 50:453-65. [PMID: 22173880 DOI: 10.1002/dvg.22004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 11/30/2011] [Accepted: 12/11/2011] [Indexed: 11/10/2022]
Abstract
Viral infection has been associated with a starvation-like state in Drosophila melanogaster. Because starvation and inhibiting TOR kinase activity in vivo result in blocked oocyte production, we hypothesized that viral infection would also result in compromised oogenesis. Wild-type flies were injected with flock house virus (FHV) and survival and embryo production were monitored. Infected flies had a dose-responsive loss of fecundity that corresponded to a global reduction in Akt/TOR signaling. Highly penetrant egg chamber destruction mid-way through oogenesis was noted and FHV coat protein was detected within developing egg chambers. As seen with in vivo TOR inhibition, oogenesis was partially rescued in loss of function discs large and merlin mutants. As expected, mutants in genes known to be involved in virus internalization and trafficking [Clathrin heavy chain (chc) and synaptotagmin] survive longer during infection. However, oogenesis was rescued only in chc mutants. This suggests that viral response mechanisms that control fly survival and egg chamber survival are separable. The genetic and signaling requirements for oocyte destruction delineated here represent a novel host-virus interaction with implications for the control of both fly and virus populations.
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Affiliation(s)
- Travis C Thomson
- Department of Obstetrics, Gynecology, and Reproductive Sciences/Division of Reproductive Endocrinology and Infertility, Yale School of Medicine, New Haven, Connecticut, USA
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38
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McLaughlin M, Patrizio P, Kayisli U, Luk J, Thomson TC, Anderson RA, Telfer EE, Johnson J. mTOR kinase inhibition results in oocyte loss characterized by empty follicles in human ovarian cortical strips cultured in vitro. Fertil Steril 2011; 96:1154-9.e1. [PMID: 22036052 DOI: 10.1016/j.fertnstert.2011.08.040] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 07/27/2011] [Accepted: 08/22/2011] [Indexed: 01/01/2023]
Abstract
OBJECTIVE To determine whether oocyte loss is induced by mTOR kinase inhibition in human cortical strips as seen in model organisms in vivo and in vitro. DESIGN Ovarian cortex was collected at two centers and cut into small strips. Strips were cultured for 6 days with or without the mTOR inhibitor rapamycin (RAP; 100 nM). Strips were then embedded in paraffin, and serial sections were prepared. SETTING Samples were collected in general obstetric (Edinburgh), gynecologic surgery (New Haven), and fertility preservation assisted reproductive technology (ART) (New Haven) practices. PATIENT(S) Ovarian cortex collected from patients (15-34 years of age) during cesarean section (donated tissue) was removed for the purposes of fertility preservation or was prepared after oophorectomy. INTERVENTION(S) Tissue was used for research purposes only, with no subsequent patient intervention. MAIN OUTCOME MEASURE(S) Follicles were counted and assessed in each serial section. Caspase activity was monitored to determine whether mTOR inhibition activated apoptosis. RESULT(S) The RAP inclusion in cultures results in significantly fewer follicles compared with ethanol vehicle-treated controls. Furthermore, RAP treatment resulted in the induction of follicles that lacked an oocyte in any serial section (30/161 follicles vs. 1/347 ethanol vehicle-treated follicles). Caspase activity was not elevated by RAP treatment. CONCLUSION(S) mTOR inhibition results in a conserved destruction of the oocyte by adjacent granulosa cells (GC) in the absence of increased caspase activity. This model of oocyte loss is not consistent with classic apoptosis/atresia.
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Affiliation(s)
- Marie McLaughlin
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, United Kingdom
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Yang Y, Primrose DA, Leung AC, Fitzsimmons RB, McDermand MC, Missellbrook A, Haskins J, Smylie AS, Hughes SC. The PP1 phosphatase flapwing regulates the activity of Merlin and Moesin in Drosophila. Dev Biol 2011; 361:412-26. [PMID: 22133918 DOI: 10.1016/j.ydbio.2011.11.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 11/09/2011] [Accepted: 11/10/2011] [Indexed: 01/21/2023]
Abstract
The signalling activities of Merlin and Moesin, two closely related members of the protein 4.1 Ezrin/Radixin/Moesin family, are regulated by conformational changes. These changes are regulated in turn by phosphorylation. The same sterile 20 kinase-Slik co-regulates Merlin or Moesin activity whereby phosphorylation inactivates Merlin, but activates Moesin. Thus, the corresponding coordinate activation of Merlin and inactivation of Moesin would require coordinated phosphatase activity. We find that Drosophila melanogaster protein phosphatase type 1 β (flapwing) fulfils this role, co-regulating dephosphorylation and altered activity of both Merlin and Moesin. Merlin or Moesin are detected in a complex with Flapwing both in-vitro and in-vivo. Directed changes in flapwing expression result in altered phosphorylation of both Merlin and Moesin. These changes in the levels of Merlin and Moesin phosphorylation following reduction of flapwing expression are associated with concomitant defects in epithelial integrity and increase in apoptosis in developing tissues such as wing imaginal discs. Functionally, the defects can be partially recapitulated by over expression of proteins that mimic constitutively phosphorylated or unphosphorylated Merlin or Moesin. Our results suggest that changes in the phosphorylation levels of Merlin and Moesin lead to changes in epithelial organization.
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Affiliation(s)
- Yang Yang
- Department of Cell Biology, University of Alberta, Edmonton, AB, Canada T6G 2H7
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40
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Yogesha SD, Sharff AJ, Giovannini M, Bricogne G, Izard T. Unfurling of the band 4.1, ezrin, radixin, moesin (FERM) domain of the merlin tumor suppressor. Protein Sci 2011; 20:2113-20. [PMID: 22012890 DOI: 10.1002/pro.751] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 10/07/2011] [Indexed: 12/30/2022]
Abstract
The merlin-1 tumor suppressor is encoded by the Neurofibromatosis-2 (Nf2) gene and loss-of-function Nf2 mutations lead to nervous system tumors in man and to several tumor types in mice. Merlin is an ERM (ezrin, radixin, moesin) family cytoskeletal protein that interacts with other ERM proteins and with components of cell-cell adherens junctions (AJs). Merlin stabilizes the links of AJs to the actin cytoskeleton. Thus, its loss destabilizes AJs, promoting cell migration and invasion, which in Nf2(+/-) mice leads to highly metastatic tumors. Paradoxically, the "closed" conformation of merlin-1, where its N-terminal four-point-one, ezrin, radixin, moesin (FERM) domain binds to its C-terminal tail domain, directs its tumor suppressor functions. Here we report the crystal structure of the human merlin-1 head domain when crystallized in the presence of its tail domain. Remarkably, unlike other ERM head-tail interactions, this structure suggests that binding of the tail provokes dimerization and dynamic movement and unfurling of the F2 motif of the FERM domain. We conclude the "closed" tumor suppressor conformer of merlin-1 is in fact an "open" dimer whose functions are disabled by Nf2 mutations that disrupt this architecture.
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Affiliation(s)
- S D Yogesha
- Cell Adhesion Laboratory, Department of Cancer Biology, The Scripps Research Institute, Jupiter, Florida 33458, USA
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41
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Jukam D, Desplan C. Binary regulation of Hippo pathway by Merlin/NF2, Kibra, Lgl, and Melted specifies and maintains postmitotic neuronal fate. Dev Cell 2011; 21:874-87. [PMID: 22055343 DOI: 10.1016/j.devcel.2011.10.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 06/21/2011] [Accepted: 10/06/2011] [Indexed: 12/19/2022]
Abstract
Patterning the Drosophila retina for color vision relies on postmitotic specification of photoreceptor subtypes. R8 photoreceptors express one of two light-sensing Rhodopsins, Rh5 or Rh6. This fate decision involves a bistable feedback loop between Melted, a PH-domain protein, and Warts, a kinase in the Hippo growth pathway. Here, we show that a subset of the Hippo pathway-Merlin, Kibra, and Lethal(2)giant larvae (Lgl), but not Expanded or Fat-is required for Warts expression and activity in R8 to specify Rh6 fate. Melted represses warts transcription to disrupt Hippo pathway activity and specify Rh5 fate. Therefore, R8 Hippo signaling exhibits ON-or-OFF regulation, promoting mutually exclusive fates. Furthermore, Merlin and Lgl are continuously required to maintain R8 neuronal subtypes. These results reveal roles for Merlin, Kibra, and Lgl in neuronal specification and maintenance and show that the Hippo pathway is reimplemented for sensory neuron fate by combining canonical and noncanonical regulatory steps.
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Affiliation(s)
- David Jukam
- Center for Developmental Genetics, Department of Biology, New York University, 100 Washington Square East, New York, NY 10003-6688, USA
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42
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A Laminin G-EGF-Laminin G module in Neurexin IV is essential for the apico-lateral localization of Contactin and organization of septate junctions. PLoS One 2011; 6:e25926. [PMID: 22022470 PMCID: PMC3195077 DOI: 10.1371/journal.pone.0025926] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 09/13/2011] [Indexed: 01/01/2023] Open
Abstract
Septate junctions (SJs) display a unique ultrastructural morphology with ladder-like electron densities that are conserved through evolution. Genetic and molecular analyses have identified a highly conserved core complex of SJ proteins consisting of three cell adhesion molecules Neurexin IV, Contactin, and Neuroglian, which interact with the cytoskeletal FERM domain protein Coracle. How these individual proteins interact to form the septal arrays that create the paracellular barrier is poorly understood. Here, we show that point mutations that map to specific domains of neurexin IV lead to formation of fewer septae and disorganization of SJs. Consistent with these observations, our in vivo domain deletion analyses identified the first Laminin G-EGF-Laminin G module in the extracellular region of Neurexin IV as necessary for the localization of and association with Contactin. Neurexin IV protein that is devoid of its cytoplasmic region is able to create septae, but fails to form a full complement of SJs. These data provide the first in vivo evidence that specific domains in Neurexin IV are required for protein-protein interactions and organization of SJs. Given the molecular conservation of SJ proteins across species, our studies may provide insights into how vertebrate axo-glial SJs are organized in myelinated axons.
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Staley BK, Irvine KD. Hippo signaling in Drosophila: recent advances and insights. Dev Dyn 2011; 241:3-15. [PMID: 22174083 DOI: 10.1002/dvdy.22723] [Citation(s) in RCA: 205] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/05/2011] [Indexed: 01/08/2023] Open
Abstract
The Hippo signaling pathway emerged from studies of Drosophila tumor suppressor genes, and is now appreciated as a major growth control pathway in vertebrates as well as arthropods. As a recently discovered pathway, key components of the pathway are continually being identified, and new insights into how the pathway is regulated and deployed are arising at a rapid pace. Over the past year and a half, significant advances have been made in our understanding of upstream regulatory inputs into Hippo signaling, key negative regulators of Hippo pathway activity have been identified, and important roles for the pathway in regeneration have been described. This review describes these and other advances, focusing on recent progress in our understanding of Hippo signaling that has come from continued studies in Drosophila.
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Affiliation(s)
- Binnaz Kucuk Staley
- Howard Hughes Medical Institute, Waksman Institute and Department of Molecular Biology and Biochemistry, Rutgers The State University of New Jersey, Piscataway, New Jersey 08854, USA
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Fong B, Barkhoudarian G, Pezeshkian P, Parsa AT, Gopen Q, Yang I. The molecular biology and novel treatments of vestibular schwannomas. J Neurosurg 2011; 115:906-14. [PMID: 21800959 DOI: 10.3171/2011.6.jns11131] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Vestibular schwannomas are histopathologically benign tumors arising from the Schwann cell sheath surrounding the vestibular branch of cranial nerve VIII and are related to the NF2 gene and its product merlin. Merlin acts as a tumor suppressor and as a mediator of contact inhibition. Thus, deficiencies in both NF2 genes lead to vestibular schwannoma development. Recently, there have been major advances in our knowledge of the molecular biology of vestibular schwannomas as well as the development of novel therapies for its treatment. In this article the authors comprehensively review the recent advances in the molecular biology and characterization of vestibular schwannomas as well as the development of modern treatments for vestibular schwannoma. For instance, merlin is involved with a number of receptors including the CD44 receptor, EGFR, and signaling pathways, such as the Ras/raf pathway and the canonical Wnt pathway. Recently, merlin was also shown to interact in the nucleus with E3 ubiquitin ligase CRL4(DCAF1). A greater understanding of the molecular mechanisms behind vestibular schwannoma tumorigenesis has begun to yield novel therapies. Some authors have shown that Avastin induces regression of progressive schwannomas by over 40% and improves hearing. An inhibitor of VEGF synthesis, PTC299, is currently in Phase II trials as a potential agent to treat vestibular schwannoma. Furthermore, in vitro studies have shown that trastuzumab (an ERBB2 inhibitor) reduces vestibular schwannoma cell proliferation. With further research it may be possible to significantly reduce morbidity and mortality rates by decreasing tumor burden, tumor volume, hearing loss, and cranial nerve deficits seen in vestibular schwannomas.
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Affiliation(s)
- Brendan Fong
- Department of Neurological Surgery, University of California, Los Angeles, CA 90095-1761, USA
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Abstract
The establishment and maintenance of apico–basal cell polarity is a pre-requisite for the formation of a functioning epithelial tissue. Many lines of evidence suggest that cell polarity perturbations favour cancer formation, even though the mechanistic basis for this link remains unclear. Studies in Drosophila have uncovered complex interactions between the conserved Hpo (Hippo) tumour suppressor pathway and apico–basal polarity determinants. The Hpo pathway is a crucial growth regulatory network whose inactivation in Drosophila epithelial tissues induces massive overproliferation. Its core consists of a phosphorylation cascade (comprising the kinases Hpo and Warts) that mediates the inactivation of the pro-growth transcriptional co-activator Yki [Yorkie; YAP (Yes-associated protein) in mammals]. Several apically located proteins, such as Merlin, Expanded or Kibra, have been identified as upstream regulators of the Hpo pathway, leading to the notion that an apical multi-molecular complex modulates core kinase activity and promotes Yki/YAP inactivation. In the present review, we explore the links between apico–basal polarity and Hpo signalling. We focus on the regulation of Yki/YAP by apical proteins, but also on how the Hpo pathway might in turn influence apical domain size as part of a regulatory feedback loop.
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Bolobolova EU, Yudina OS, Dorogova NV. Drosophila tumor suppressor merlin is essential for mitochondria morphogenesis during spermatogenesis in Drosophila melanogaster. ACTA ACUST UNITED AC 2011. [DOI: 10.1134/s1990519x11020040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Fernández BG, Gaspar P, Brás-Pereira C, Jezowska B, Rebelo SR, Janody F. Actin-Capping Protein and the Hippo pathway regulate F-actin and tissue growth in Drosophila. Development 2011; 138:2337-46. [PMID: 21525075 DOI: 10.1242/dev.063545] [Citation(s) in RCA: 236] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The conserved Hippo tumor suppressor pathway is a key kinase cascade that controls tissue growth by regulating the nuclear import and activity of the transcription co-activator Yorkie. Here, we report that the actin-Capping Protein αβ heterodimer, which regulates actin polymerization, also functions to suppress inappropriate tissue growth by inhibiting Yorkie activity. Loss of Capping Protein activity results in abnormal accumulation of apical F-actin, reduced Hippo pathway activity and the ectopic expression of several Yorkie target genes that promote cell survival and proliferation. Reduction of two other actin-regulatory proteins, Cofilin and the cyclase-associated protein Capulet, cause abnormal F-actin accumulation, but only the loss of Capulet, like that of Capping Protein, induces ectopic Yorkie activity. Interestingly, F-actin also accumulates abnormally when Hippo pathway activity is reduced or abolished, independently of Yorkie activity, whereas overexpression of the Hippo pathway component expanded can partially reverse the abnormal accumulation of F-actin in cells depleted for Capping Protein. Taken together, these findings indicate a novel interplay between Hippo pathway activity and actin filament dynamics that is essential for normal growth control.
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Dubatolova TD, Dorogova NV, Omel’yanchuk LV, Chang LS. Duration of the cell cycle phases in mutants for the tumor suppressor Merlin in Drosophila melanogaster. RUSS J GENET+ 2011. [DOI: 10.1134/s1022795411040041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Thaxton C, Bott M, Walker B, Sparrow NA, Lambert S, Fernandez-Valle C. Schwannomin/merlin promotes Schwann cell elongation and influences myelin segment length. Mol Cell Neurosci 2010; 47:1-9. [PMID: 21182951 DOI: 10.1016/j.mcn.2010.12.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 11/19/2010] [Accepted: 12/09/2010] [Indexed: 11/30/2022] Open
Abstract
The Neurofibromatosis type 2 tumor suppressor, schwannomin (Sch) is a plasma membrane-cytoskeleton linking protein that regulates receptor signaling and actin dynamics. We examined Sch's role in specifying morphological changes needed for Schwann cell (SC) function in vitro. Isolated Sch-GFP-expressing SCs extended bipolar processes 82% longer than those formed by GFP-expressing cells. In contrast, SCs expressing dominant negative Sch-BBA-GFP extended bipolar processes 16% shorter than controls and 64% shorter than Sch-GFP-expressing SCs. nf2 gene inactivation caused isolated mouse SCs to transition from bipolar to multipolar cells. Live imaging revealed that SCs co-expressing Sch-GFP and dominant negative RacN17 behaved similarly in dorsal root ganglion explant cultures; they quickly aligned on axons and slowly elongated bipolar processes. In contrast, SCs expressing constitutively active RacV12 underwent continuous transitions in morphology that interfered with axon alignment. When co-cultured with neurons under myelin-promoting conditions, Sch-GFP-expressing SCs elaborated longer myelin segments than GFP-expressing SCs. In contrast, Sch-BBA-GFP-expressing SCs failed to align on or myelinate axons. Together, these results demonstrate that Sch plays an essential role in inducing and/or maintaining the SC's spindle shape and suggest that the mechanism involves Sch-dependent inhibition of Rac activity. By stabilizing the bipolar morphology, Sch promotes the alignment of SCs with axons and ultimately influences myelin segment length.
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Affiliation(s)
- Courtney Thaxton
- Department of Molecular Biology and Microbiology, Burnett School of Biomedical Science, College of Medicine, University of Central Florida, Health Science Campus, 6900 Lake Nona Boulevard, Orlando, FL 32827, USA
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Pirraglia C, Walters J, Myat MM. Pak1 control of E-cadherin endocytosis regulates salivary gland lumen size and shape. Development 2010; 137:4177-89. [PMID: 21068057 DOI: 10.1242/dev.048827] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Generating and maintaining proper lumen size and shape in tubular organs is essential for organ function. Here, we demonstrate a novel role for p21-activated kinase 1 (Pak1) in defining the size and shape of the Drosophila embryonic salivary gland lumen by regulating the size and elongation of the apical domain of individual cells. Pak1 mediates these effects by decreasing and increasing E-cadherin levels at the adherens junctions and basolateral membrane, respectively, through Rab5- and Dynamin-dependent endocytosis. We also demonstrate that Cdc42 and Merlin act together with Pak1 to control lumen size. A role for Pak1 in E-cadherin endocytosis is supported by our studies of constitutively active Pak1, which induces the formation of multiple intercellular lumens in the salivary gland in a manner dependent on Rab5, Dynamin and Merlin. These studies demonstrate a novel and crucial role for Pak1 and E-cadherin endocytosis in determining lumen size and shape, and also identify a mechanism for multiple lumen formation, a poorly understood process that occurs in normal embryonic development and pathological conditions.
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Affiliation(s)
- Carolyn Pirraglia
- BCMB Program of Weill Graduate School of Medical Sciences at Cornell University, New York, NY 10065, USA
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