1
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Seong CS, Huang C, Boese AC, Hou Y, Koo J, Mouw JK, Rupji M, Joseph G, Johnston HR, Claussen H, Switchenko JM, Behera M, Churchman M, Kolesar JM, Arnold SM, Kerrigan K, Akerley W, Colman H, Johns MA, Arciero C, Zhou W, Marcus AI, Ramalingam SS, Fu H, Gilbert-Ross M. Loss of the endocytic tumor suppressor HD-PTP phenocopies LKB1 and promotes RAS-driven oncogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.26.525772. [PMID: 36747658 PMCID: PMC9900931 DOI: 10.1101/2023.01.26.525772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Oncogenic RAS mutations drive aggressive cancers that are difficult to treat in the clinic, and while direct inhibition of the most common KRAS variant in lung adenocarcinoma (G12C) is undergoing clinical evaluation, a wide spectrum of oncogenic RAS variants together make up a large percentage of untargetable lung and GI cancers. Here we report that loss-of-function alterations (mutations and deep deletions) in the gene that encodes HD-PTP (PTPN23) occur in up to 14% of lung cancers in the ORIEN Avatar lung cancer cohort, associate with adenosquamous histology, and occur alongside an altered spectrum of KRAS alleles. Furthermore, we show that in publicly available early-stage NSCLC studies loss of HD-PTP is mutually exclusive with loss of LKB1, which suggests they restrict a common oncogenic pathway in early lung tumorigenesis. In support of this, knockdown of HD-PTP in RAS-transformed lung cancer cells is sufficient to promote FAK-dependent invasion. Lastly, knockdown of the Drosophila homolog of HD-PTP (dHD-PTP/Myopic) synergizes to promote RAS-dependent neoplastic progression. Our findings highlight a novel tumor suppressor that can restrict RAS-driven lung cancer oncogenesis and identify a targetable pathway for personalized therapeutic approaches for adenosquamous lung cancer.
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Affiliation(s)
- Chang-Soo Seong
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA USA
| | - Chunzi Huang
- Cancer Animal Models Shared Resource, Winship Cancer Institute of Emory University, Atlanta, GA, USA
| | - Austin C. Boese
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA USA
- Cancer Biology Graduate Program, Laney Graduate School, Emory University, Atlanta, GA, USA
| | - Yuning Hou
- Cancer Animal Models Shared Resource, Winship Cancer Institute of Emory University, Atlanta, GA, USA
| | - Junghui Koo
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA USA
| | - Janna K. Mouw
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA USA
| | - Manali Rupji
- Biostatistics Shared Resource, Winship Cancer Institute of Emory University, Atlanta, GA, USA
| | - Greg Joseph
- Data and Technology Applications Shared Resource, Winship Cancer Institute of Emory University, Atlanta, GA, USA
| | | | - Henry Claussen
- Emory Integrated Computational Core, Emory University, Atlanta, GA
| | - Jeffrey M. Switchenko
- Biostatistics Shared Resource, Winship Cancer Institute of Emory University, Atlanta, GA, USA
| | - Madhusmita Behera
- Data and Technology Applications Shared Resource, Winship Cancer Institute of Emory University, Atlanta, GA, USA
| | | | - Jill M. Kolesar
- Markey Cancer Center, University of Kentucky, Lexington, KY, USA
| | | | - Katie Kerrigan
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Wallace Akerley
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | - Howard Colman
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT, USA
| | | | - Cletus Arciero
- Department of Surgery, Emory University School of Medicine, Atlanta, GA USA
| | - Wei Zhou
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA USA
- Winship Cancer Institute of Emory University, Atlanta, GA, USA
| | - Adam I. Marcus
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA USA
- Winship Cancer Institute of Emory University, Atlanta, GA, USA
| | - Suresh S. Ramalingam
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA USA
- Winship Cancer Institute of Emory University, Atlanta, GA, USA
| | - Haian Fu
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA USA
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - Melissa Gilbert-Ross
- Department of Hematology and Medical Oncology, Emory University School of Medicine, Atlanta, GA USA
- Winship Cancer Institute of Emory University, Atlanta, GA, USA
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2
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Weisman NY. Genetic and Epigenetic Pathways of lethal (2) giant larvae Tumor Suppressor in Drosophila melanogaster. RUSS J GENET+ 2019. [DOI: 10.1134/s1022795419020145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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3
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Perea D, Guiu J, Hudry B, Konstantinidou C, Milona A, Hadjieconomou D, Carroll T, Hoyer N, Natarajan D, Kallijärvi J, Walker JA, Soba P, Thapar N, Burns AJ, Jensen KB, Miguel-Aliaga I. Ret receptor tyrosine kinase sustains proliferation and tissue maturation in intestinal epithelia. EMBO J 2017; 36:3029-3045. [PMID: 28899900 PMCID: PMC5641678 DOI: 10.15252/embj.201696247] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 07/26/2017] [Accepted: 07/28/2017] [Indexed: 01/25/2023] Open
Abstract
Expression of the Ret receptor tyrosine kinase is a defining feature of enteric neurons. Its importance is underscored by the effects of its mutation in Hirschsprung disease, leading to absence of gut innervation and severe gastrointestinal symptoms. We report a new and physiologically significant site of Ret expression in the intestine: the intestinal epithelium. Experiments in Drosophila indicate that Ret is expressed both by enteric neurons and adult intestinal epithelial progenitors, which require Ret to sustain their proliferation. Mechanistically, Ret is engaged in a positive feedback loop with Wnt/Wingless signalling, modulated by Src and Fak kinases. We find that Ret is also expressed by the developing intestinal epithelium of mice, where its expression is maintained into the adult stage in a subset of enteroendocrine/enterochromaffin cells. Mouse organoid experiments point to an intrinsic role for Ret in promoting epithelial maturation and regulating Wnt signalling. Our findings reveal evolutionary conservation of the positive Ret/Wnt signalling feedback in both developmental and homeostatic contexts. They also suggest an epithelial contribution to Ret loss‐of‐function disorders such as Hirschsprung disease.
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Affiliation(s)
- Daniel Perea
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| | - Jordi Guiu
- BRIC-Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen N, Denmark
| | - Bruno Hudry
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| | | | - Alexandra Milona
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| | - Dafni Hadjieconomou
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| | - Thomas Carroll
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
| | - Nina Hoyer
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf (UKE), University of Hamburg, Hamburg, Germany
| | - Dipa Natarajan
- Stem Cells and Regenerative Medicine, UCL Institute of Child Health, London, UK
| | - Jukka Kallijärvi
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - James A Walker
- Center for Human Genetic Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Peter Soba
- Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf (UKE), University of Hamburg, Hamburg, Germany
| | - Nikhil Thapar
- Stem Cells and Regenerative Medicine, UCL Institute of Child Health, London, UK
| | - Alan J Burns
- Stem Cells and Regenerative Medicine, UCL Institute of Child Health, London, UK
| | - Kim B Jensen
- BRIC-Biotech Research and Innovation Centre, University of Copenhagen, Copenhagen N, Denmark.,The Danish Stem Cell Center (Danstem), Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Irene Miguel-Aliaga
- MRC London Institute of Medical Sciences, Imperial College London, London, UK
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Functional screening of Alzheimer risk loci identifies PTK2B as an in vivo modulator and early marker of Tau pathology. Mol Psychiatry 2017; 22:874-883. [PMID: 27113998 PMCID: PMC5444024 DOI: 10.1038/mp.2016.59] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 12/12/2015] [Accepted: 01/20/2016] [Indexed: 01/02/2023]
Abstract
A recent genome-wide association meta-analysis for Alzheimer's disease (AD) identified 19 risk loci (in addition to APOE) in which the functional genes are unknown. Using Drosophila, we screened 296 constructs targeting orthologs of 54 candidate risk genes within these loci for their ability to modify Tau neurotoxicity by quantifying the size of >6000 eyes. Besides Drosophila Amph (ortholog of BIN1), which we previously implicated in Tau pathology, we identified p130CAS (CASS4), Eph (EPHA1), Fak (PTK2B) and Rab3-GEF (MADD) as Tau toxicity modulators. Of these, the focal adhesion kinase Fak behaved as a strong Tau toxicity suppressor in both the eye and an independent focal adhesion-related wing blister assay. Accordingly, the human Tau and PTK2B proteins biochemically interacted in vitro and PTK2B co-localized with hyperphosphorylated and oligomeric Tau in progressive pathological stages in the brains of AD patients and transgenic Tau mice. These data indicate that PTK2B acts as an early marker and in vivo modulator of Tau toxicity.
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Mapping Heart Development in Flies: Src42A Acts Non-Autonomously to Promote Heart Tube Formation in Drosophila. Vet Sci 2017; 4:vetsci4020023. [PMID: 29056682 PMCID: PMC5606601 DOI: 10.3390/vetsci4020023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 11/27/2016] [Accepted: 12/07/2016] [Indexed: 12/26/2022] Open
Abstract
Congenital heart defects, clinically identified in both small and large animals, are multifactorial and complex. Although heritable factors are known to have a role in cardiovascular disease, the full genetic aetiology remains unclear. Model organism research has proven valuable in providing a deeper understanding of the essential factors in heart development. For example, mouse knock-out studies reveal a role for the Integrin adhesion receptor in cardiac tissue. Recent research in Drosophila melanogaster (the fruit fly), a powerful experimental model, has demonstrated that the link between the extracellular matrix and the cell, mediated by Integrins, is required for multiple aspects of cardiogenesis. Here we test the hypothesis that Integrins signal to the heart cells through Src42A kinase. Using the powerful genetics and cell biology analysis possible in Drosophila, we demonstrate that Src42A acts in early events of heart tube development. Careful examination of mutant heart tissue and genetic interaction data suggests that Src42A’s role is independent of Integrin and the Integrin-related Focal Adhesion Kinase. Rather, Src42A acts non-autonomously by promoting programmed cell death of the amnioserosa, a transient tissue that neighbors the developing heart.
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Schardt L, Ander JJ, Lohmann I, Papagiannouli F. Stage-specific control of niche positioning and integrity in the Drosophila testis. Mech Dev 2015; 138 Pt 3:336-48. [PMID: 26226434 DOI: 10.1016/j.mod.2015.07.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 06/23/2015] [Accepted: 07/24/2015] [Indexed: 12/11/2022]
Abstract
A fundamental question is how complex structures are maintained after their initial specification. Stem cells reside in a specialized microenvironment, called niche, which provides essential signals controlling stem cell behavior. We addressed this question by studying the Drosophila male stem cell niche, called the hub. Once specified, the hub cells need to maintain their position and architectural integrity through embryonic, larval and pupal stages of testis organogenesis and during adult life. The Hox gene Abd-B, in addition to its described role in male embryonic gonads, maintains the architecture and positioning of the larval hub from the germline by affecting integrin localization in the neighboring somatic cyst cells. We find that the AbdB-Boss/Sev cascade affects integrin independent of Talin, while genetic interactions depict integrin as the central downstream player in this system. Focal adhesion and integrin-adaptor proteins within the somatic stem cells and cyst cells, such as Paxillin, Pinch and Vav, also contribute to proper hub integrity and positioning. During adult stages, hub positioning is controlled by Abd-B activity in the outer acto-myosin sheath, while Abd-B expression in adult spermatocytes exerts no effect on hub positioning and integrin localization. Our data point at a cell- and stage-specific function of Abd-B and suggest that the occurrence of new cell types and cell interactions in the course of testis organogenesis made it necessary to adapt the whole system by reusing the same players for male stem cell niche positioning and integrity in an alternative manner.
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Affiliation(s)
- Lisa Schardt
- Centre for Organismal Studies (COS) Heidelberg, Cell Networks - Cluster of Excellence, University of Heidelberg, D-69120, Germany; Deutsches Krebsforschungszentrum (DKFZ), D-69120, Germany
| | - Janina-Jacqueline Ander
- Centre for Organismal Studies (COS) Heidelberg, Cell Networks - Cluster of Excellence, University of Heidelberg, D-69120, Germany
| | - Ingrid Lohmann
- Centre for Organismal Studies (COS) Heidelberg, Cell Networks - Cluster of Excellence, University of Heidelberg, D-69120, Germany.
| | - Fani Papagiannouli
- Centre for Organismal Studies (COS) Heidelberg, Cell Networks - Cluster of Excellence, University of Heidelberg, D-69120, Germany.
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7
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Cordero JB, Ridgway RA, Valeri N, Nixon C, Frame MC, Muller WJ, Vidal M, Sansom OJ. c-Src drives intestinal regeneration and transformation. EMBO J 2014; 33:1474-91. [PMID: 24788409 PMCID: PMC4194090 DOI: 10.1002/embj.201387454] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 03/11/2014] [Accepted: 04/08/2014] [Indexed: 12/11/2022] Open
Abstract
The non-receptor tyrosine kinase c-Src, hereafter referred to as Src, is overexpressed or activated in multiple human malignancies. There has been much speculation about the functional role of Src in colorectal cancer (CRC), with Src amplification and potential activating mutations in up to 20% of the human tumours, although this has never been addressed due to multiple redundant family members. Here, we have used the adult Drosophila and mouse intestinal epithelium as paradigms to define a role for Src during tissue homeostasis, damage-induced regeneration and hyperplasia. Through genetic gain and loss of function experiments, we demonstrate that Src is necessary and sufficient to drive intestinal stem cell (ISC) proliferation during tissue self-renewal, regeneration and tumourigenesis. Surprisingly, Src plays a non-redundant role in the mouse intestine, which cannot be substituted by the other family kinases Fyn and Yes. Mechanistically, we show that Src drives ISC proliferation through upregulation of EGFR and activation of Ras/MAPK and Stat3 signalling. Therefore, we demonstrate a novel essential role for Src in intestinal stem/progenitor cell proliferation and tumourigenesis initiation in vivo.
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Affiliation(s)
- Julia B Cordero
- The Beatson Institute for Cancer Research, Bearsden Glasgow, UK
| | | | | | - Colin Nixon
- The Beatson Institute for Cancer Research, Bearsden Glasgow, UK
| | - Margaret C Frame
- Edinburgh Cancer Research Centre Institute of Genetics & Molecular Medicine University of Edinburgh, Edinburgh, UK
| | - William J Muller
- Goodman Cancer Research Center McGill University, Montreal, QC, Canada
| | - Marcos Vidal
- The Beatson Institute for Cancer Research, Bearsden Glasgow, UK
| | - Owen J Sansom
- The Beatson Institute for Cancer Research, Bearsden Glasgow, UK
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8
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Macagno JP, Diaz Vera J, Yu Y, MacPherson I, Sandilands E, Palmer R, Norman JC, Frame M, Vidal M. FAK acts as a suppressor of RTK-MAP kinase signalling in Drosophila melanogaster epithelia and human cancer cells. PLoS Genet 2014; 10:e1004262. [PMID: 24676055 PMCID: PMC3967952 DOI: 10.1371/journal.pgen.1004262] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2013] [Accepted: 02/10/2014] [Indexed: 11/18/2022] Open
Abstract
Receptor Tyrosine Kinases (RTKs) and Focal Adhesion Kinase (FAK) regulate multiple signalling pathways, including mitogen-activated protein (MAP) kinase pathway. FAK interacts with several RTKs but little is known about how FAK regulates their downstream signalling. Here we investigated how FAK regulates signalling resulting from the overexpression of the RTKs RET and EGFR. FAK suppressed RTKs signalling in Drosophila melanogaster epithelia by impairing MAPK pathway. This regulation was also observed in MDA-MB-231 human breast cancer cells, suggesting it is a conserved phenomenon in humans. Mechanistically, FAK reduced receptor recycling into the plasma membrane, which resulted in lower MAPK activation. Conversely, increasing the membrane pool of the receptor increased MAPK pathway signalling. FAK is widely considered as a therapeutic target in cancer biology; however, it also has tumour suppressor properties in some contexts. Therefore, the FAK-mediated negative regulation of RTK/MAPK signalling described here may have potential implications in the designing of therapy strategies for RTK-driven tumours.
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Affiliation(s)
- Juan Pablo Macagno
- Cancer Research UK Beatson Institute, Garscube Estate, Glasgow, United Kingdom
| | - Jesica Diaz Vera
- Cancer Research UK Beatson Institute, Garscube Estate, Glasgow, United Kingdom
| | - Yachuan Yu
- Cancer Research UK Beatson Institute, Garscube Estate, Glasgow, United Kingdom
| | - Iain MacPherson
- Cancer Research UK Beatson Institute, Garscube Estate, Glasgow, United Kingdom
| | - Emma Sandilands
- Edinburgh Cancer Research UK Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Ruth Palmer
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Jim C. Norman
- Cancer Research UK Beatson Institute, Garscube Estate, Glasgow, United Kingdom
| | - Margaret Frame
- Edinburgh Cancer Research UK Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom
| | - Marcos Vidal
- Cancer Research UK Beatson Institute, Garscube Estate, Glasgow, United Kingdom
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Golubovskaya VM. Targeting FAK in human cancer: from finding to first clinical trials. Front Biosci (Landmark Ed) 2014; 19:687-706. [PMID: 24389213 DOI: 10.2741/4236] [Citation(s) in RCA: 132] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
It is twenty years since Focal Adhesion Kinase (FAK) was found to be overexpressed in many types of human cancer. FAK plays an important role in adhesion, spreading, motility, invasion, metastasis, survival, angiogenesis, and recently has been found to play an important role as well in epithelial to mesenchymal transition (EMT), cancer stem cells and tumor microenvironment. FAK has kinase-dependent and kinase independent scaffolding, cytoplasmic and nuclear functions. Several years ago FAK was proposed as a potential therapeutic target; the first clinical trials were just reported, and they supported further studies of FAK as a promising therapeutic target. This review discusses the main functions of FAK in cancer, and specifically focuses on recent novel findings on the role of FAK in cancer stem cells, microenvironment, epithelial-to-mesenchymal transition, invasion, metastasis, and also highlight new approaches of targeting FAK and critically discuss challenges that lie ahead for its targeted therapeutics. The review provides a summary of translational approaches of FAK-targeted and combination therapies and outline perspectives and future directions of FAK research.
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Goulas S, Conder R, Knoblich J. The Par complex and integrins direct asymmetric cell division in adult intestinal stem cells. Cell Stem Cell 2013; 11:529-40. [PMID: 23040479 PMCID: PMC3465556 DOI: 10.1016/j.stem.2012.06.017] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 03/09/2012] [Accepted: 06/07/2012] [Indexed: 01/25/2023]
Abstract
The adult Drosophila midgut is maintained by intestinal stem cells (ISCs) that generate both self-renewing and differentiating daughter cells. How this asymmetry is generated is currently unclear. Here, we demonstrate that asymmetric ISC division is established by a unique combination of extracellular and intracellular polarity mechanisms. We show that Integrin-dependent adhesion to the basement membrane induces cell-intrinsic polarity and results in the asymmetric segregation of the Par proteins Par-3, Par-6, and aPKC into the apical daughter cell. Cell-specific knockdown and overexpression experiments suggest that increased activity of aPKC enhances Delta/Notch signaling in one of the two daughter cells to induce terminal differentiation. Perturbing this mechanism or altering the orientation of ISC division results in the formation of intestinal tumors. Our data indicate that mechanisms for intrinsically asymmetric cell division can be adapted to allow for the flexibility in lineage decisions that is required in adult stem cells.
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Affiliation(s)
- Spyros Goulas
- Institute of Molecular Biotechnology of the Austrian Academy of Science (IMBA), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Ryan Conder
- Institute of Molecular Biotechnology of the Austrian Academy of Science (IMBA), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Juergen A. Knoblich
- Institute of Molecular Biotechnology of the Austrian Academy of Science (IMBA), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
- Corresponding author
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11
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Neurofibromin mediates FAK signaling in confining synapse growth at Drosophila neuromuscular junctions. J Neurosci 2013; 32:16971-81. [PMID: 23175848 DOI: 10.1523/jneurosci.1756-12.2012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neurofibromatosis type I (NF1), caused by the mutation in the NF1 gene, is characterized by multiple pathological symptoms. Importantly, ~50% of NF1 patients also suffer learning difficulty. Although downstream pathways are well studied, regulation of the NF1-encoded neurofibromin protein is less clear. Here, we focused on the pathophysiology of Drosophila NF1 mutants in synaptic growth at neuromuscular junctions. Our analysis suggests that the Drosophila neurofibromin protein NF1 is required to constrain synaptic growth and transmission. NF1 functions downstream of the Drosophila focal adhesion kinase (FAK) Fak56 and physically interacts with Fak56. The N-terminal region of NF1 mediates the interaction with Fak56 and is required for the signaling activity and presynaptic localization of NF1. In presynapses, NF1 acts via the cAMP pathway, but independent of its GAP activity, to restrain synaptic growth. Thus, presynaptic FAK signaling may be disrupted, causing abnormal synaptic growth and transmission in the NF1 genetic disorder.
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12
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Papagiannouli F, Lohmann I. Shaping the niche: lessons from the Drosophila testis and other model systems. Biotechnol J 2012; 7:723-36. [PMID: 22488937 DOI: 10.1002/biot.201100352] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 01/31/2012] [Accepted: 02/27/2012] [Indexed: 11/12/2022]
Abstract
Stem cells are fascinating, as they supply the cells that construct our adult bodies and replenish, as we age, worn out, damaged, and diseased tissues. Stem cell regulation relies on intrinsic signals but also on inputs emanating from the neighbouring niche. The Drosophila testis provides an excellent system for studying such processes. Although recent advances have uncovered several signalling, cytoskeletal and other factors affecting niche homeostasis and testis differentiation, many aspects of niche regulation and maintenance remain unsolved. In this review, we discuss aspects of niche establishment and integrity not yet fully understood and we compare it to the current knowledge in other model systems such as vertebrates and plants. We also address specific questions on stem cell maintenance and niche regulation in the Drosophila testis under the control of Hox genes. Finally, we provide insights on the striking functional conservation of homologous genes in plants and animals and their respective stem cell niches. Elucidating conserved mechanisms of stem cell control in both lineages could reveal the importance underlying this conservation and justify the evolutionary pressure to adapt homologous molecules for performing the same task.
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Affiliation(s)
- Fani Papagiannouli
- Centre for Organismal Studies (COS) Heidelberg and CellNetworks - Cluster of Excellence, Heidelberg, Germany.
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13
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Nagaosa K, Okada R, Nonaka S, Takeuchi K, Fujita Y, Miyasaka T, Manaka J, Ando I, Nakanishi Y. Integrin βν-mediated phagocytosis of apoptotic cells in Drosophila embryos. J Biol Chem 2011; 286:25770-7. [PMID: 21592968 DOI: 10.1074/jbc.m110.204503] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To identify molecules that play roles in the clearance of apoptotic cells by Drosophila phagocytes, we examined a series of monoclonal antibodies raised against larval hemocytes for effects on phagocytosis in vitro. One antibody that inhibited phagocytosis recognized terribly reduced optic lobes (Trol), a core protein of the perlecan-type proteoglycan, and the level of phagocytosis in embryos of a Trol-lacking fly line was lower than in a control line. The treatment of a hemocyte cell line with a recombinant Trol protein containing the amino acid sequence RGD augmented the phosphorylation of focal adhesion kinase, a hallmark of integrin activation. A loss of integrin βν, one of the two β subunits of Drosophila integrin, brought about a reduction in the level of apoptotic cell clearance in embryos. The presence of integrin βν at the surface of embryonic hemocytes was confirmed, and forced expression of integrin βν in hemocytes of an integrin βν-lacking fly line recovered the defective phenotype of phagocytosis. Finally, the level of phagocytosis in a fly line that lacks both integrin βν and Draper, another receptor required for the phagocytosis of apoptotic cells, was lower than that in a fly line lacking either protein. We suggest that integrin βν serves as a phagocytosis receptor responsible for the clearance of apoptotic cells in Drosophila, independent of Draper.
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Affiliation(s)
- Kaz Nagaosa
- Graduate School of Medical Science, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
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Delon I, Brown NH. The integrin adhesion complex changes its composition and function during morphogenesis of an epithelium. J Cell Sci 2009; 122:4363-74. [PMID: 19903692 PMCID: PMC2779134 DOI: 10.1242/jcs.055996] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Cell adhesion to the extracellular matrix (ECM) is mediated by the integrin family of transmembrane receptors. Integrins link ECM ligands to the cytoskeleton, providing strong attachment to enable cell-shape change and tissue integrity. This connection is made possible by an intracellular complex of proteins, which links to actin filaments and controls signalling cascades that regulate cytoskeletal rearrangements. We have identified stress-fibre-associated focal adhesions that change their composition during tissue morphogenesis. Early expression of alphaPS1betaPS integrin decreases the levels of the actin-nucleating factors Enabled, Diaphanous and profilin, as well as downregulating the amount of F-actin incorporated into the stress fibres. As follicle cells mature in their developmental pathway and become squamous, the integrin in the focal adhesions changes from alphaPS1betaPS to alphaPS2betaPS. During the switch, stress fibres increase their length and change orientation, first changing by 90 degrees and then reorienting back. The normal rapid reorientation requires new expression of alphaPS2betaPS, which also permits recruitment of the adaptor protein tensin. Unexpectedly, it is the extracellular portion of the alphaPS2 subunit that provides the specificity for intracellular recruitment of tensin. Molecular variation of the integrin complex is thus a key component of developmentally programmed morphogenesis.
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Affiliation(s)
- Isabelle Delon
- Gurdon Institute and Department of Physiology, Development and Neuroscience, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
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Zhang M, Wang H, Li D, Xu X. A novel focal adhesion kinase from Marsupenaeus japonicus and its response to WSSV infection. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2009; 33:533-539. [PMID: 19013481 DOI: 10.1016/j.dci.2008.10.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Revised: 10/17/2008] [Accepted: 10/18/2008] [Indexed: 05/27/2023]
Abstract
Focal adhesion kinase (FAK) is a cytoplasmic protein-tyrosine kinase involved in integrin-mediated signal transduction which regulates multiple cell functions in mammalian cells. In contrast to the well document of FAK in mammalian cells, the properties of FAK in crustacean have not been reported yet and even none of their gene or protein sequences is known to date. Here, we report for the first time the cloning of FAK from Marsupenaeus japonicus (designated as MjFAK) and the identification of its involvement in the virus infection and host defense. Sequence analysis displayed that MjFAK shared strong similarity to FAK family protein-tyrosine kinase, including conserved tyrosine phosphorylation sites, PTK domain and FAT domain. Immunofluorescence staining analysis showed that MjFAK was located prominently at the cell periphery and partly in cytoplasm and nucleus. Notably, considerable high content of MjFAK and MjFAK (pY399) were found in shrimp, which differs greatly from the low level of endogenous FAK and pFAK in the mammalian cells. It implies that pMjFAK may play a significant role in shrimp. Moreover, pMjFAK increased at the early infection stage, and the hemocyte adhesion activity of fibronectin also increased significantly accompanying with its phosphorylation. These results suggest that pMjFAK may not only promote the WSSV infection, but also participate in the defense mechanism via the enhancement of the immune-cell adhesion. Our data provide a clue to recognize the FAK-mediated signaling connection in the control of immunity and virus infection in crustaceans, which will be helpful to shrimp viral disease control.
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Affiliation(s)
- Mingchang Zhang
- School of Life Science, Xiamen University, Xiamen 361005, PR China
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16
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Marmaras VJ, Lampropoulou M. Regulators and signalling in insect haemocyte immunity. Cell Signal 2009; 21:186-95. [DOI: 10.1016/j.cellsig.2008.08.014] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Accepted: 08/24/2008] [Indexed: 02/06/2023]
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17
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Tsai PI, Kao HH, Grabbe C, Lee YT, Ghose A, Lai TT, Peng KP, Van Vactor D, Palmer RH, Chen RH, Yeh SR, Chien CT. Fak56 functions downstream of integrin alphaPS3betanu and suppresses MAPK activation in neuromuscular junction growth. Neural Dev 2008; 3:26. [PMID: 18925939 PMCID: PMC2576229 DOI: 10.1186/1749-8104-3-26] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Accepted: 10/16/2008] [Indexed: 12/11/2022] Open
Abstract
Background Focal adhesion kinase (FAK) functions in cell migration and signaling through activation of the mitogen-activated protein kinase (MAPK) signaling cascade. Neuronal function of FAK has been suggested to control axonal branching; however, the underlying mechanism in this process is not clear. Results We have generated mutants for the Drosophila FAK gene, Fak56. Null Fak56 mutants display overgrowth of larval neuromuscular junctions (NMJs). Localization of phospho-FAK and rescue experiments suggest that Fak56 is required in presynapses to restrict NMJ growth. Genetic analyses imply that FAK mediates the signaling pathway of the integrin αPS3βν heterodimer and functions redundantly with Src. At NMJs, Fak56 downregulates ERK activity, as shown by diphospho-ERK accumulation in Fak56 mutants, and suppression of Fak56 mutant NMJ phenotypes by reducing ERK activity. Conclusion We conclude that Fak56 is required to restrict NMJ growth during NMJ development. Fak56 mediates an extracellular signal through the integrin receptor. Unlike its conventional role in activating MAPK/ERK, Fak56 suppresses ERK activation in this process. These results suggest that Fak56 mediates a specific neuronal signaling pathway distinct from that in other cellular processes.
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Affiliation(s)
- Pei-I Tsai
- Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan.
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18
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Alves-Silva J, Hahn I, Huber O, Mende M, Reissaus A, Prokop A. Prominent actin fiber arrays in Drosophila tendon cells represent architectural elements different from stress fibers. Mol Biol Cell 2008; 19:4287-97. [PMID: 18667532 PMCID: PMC2555930 DOI: 10.1091/mbc.e08-02-0182] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Tendon cells are specialized cells of the insect epidermis that connect basally attached muscle tips to the cuticle on their apical surface via prominent arrays of microtubules. Tendon cells of Drosophila have become a useful genetic model system to address questions with relevance to cell and developmental biology. Here, we use light, confocal, and electron microscopy to present a refined model of the subcellular organization of tendon cells. We show that prominent arrays of F-actin exist in tendon cells that fully overlap with the microtubule arrays, and that type II myosin accumulates in the same area. The F-actin arrays in tendon cells seem to represent a new kind of actin structure, clearly distinct from stress fibers. They are highly resistant to F-actin-destabilizing drugs, to the application of myosin blockers, and to loss of integrin, Rho1, or mechanical force. They seem to represent an important architectural element of tendon cells, because they maintain a connection between apical and basal surfaces even when microtubule arrays of tendon cells are dysfunctional. Features reported here and elsewhere for tendon cells are reminiscent of the structural and molecular features of support cells in the inner ear of vertebrates, and they might have potential translational value.
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Affiliation(s)
- Juliana Alves-Silva
- Faculty of Life Sciences, Wellcome Trust Centre of Cell-Matrix Research, Manchester M13 9PT, United Kingdom
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19
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Ueda A, Grabbe C, Lee J, Lee J, Palmer RH, Wu CF. Mutation of Drosophila focal adhesion kinase induces bang-sensitive behavior and disrupts glial function, axonal conduction and synaptic transmission. Eur J Neurosci 2008; 27:2860-70. [PMID: 18540882 DOI: 10.1111/j.1460-9568.2008.06252.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The role of the conserved focal adhesion kinase (FAK) family of protein tyrosine kinases in the development and physiological functions of the CNS has long been an area of interest among neuroscientists. In this report, we observe that Drosophila mutants lacking Fak56 exhibit a decreased lifespan, accompanied by a bang-sensitive phenotype, which is characterized by sensitivity to mechanical and high-frequency electrical stimulation. Fak56 mutant animals display lower thresholds and higher rates of seizures in response to electroconvulsive stimuli. Direct measurements of action potential conduction in larval segmental nerves demonstrate a slowed propagation speed and failure during high-frequency nerve stimulation. In addition, neuromuscular junctions in Fak56 mutant animals display transmission blockade during high-frequency activity as a result of action potential failure. Endogenous Fak56 protein is abundant in glial cells ensheathing the axon bundles, and structural alterations of segmental nerve bundles can be observed in mutants. Manipulation of Fak56 function specifically in glial cells also disrupts action potential conduction and neurotransmission, suggesting a glial component in the Fak56 bang-sensitive phenotype. Furthermore, we show that increased intracellular calcium levels result in the dephosphorylation of endogenous Fak56 protein in Drosophila cell lines, in parallel with our observations of highly variable synaptic potentials at a higher Ca2+ level in Fak56 mutant larvae. Together these findings suggest that modulation of Fak56 function is important for action potential propagation and Ca2+-regulated neuromuscular transmission in vivo.
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Affiliation(s)
- Atsushi Ueda
- Department of Biological Sciences, University of Iowa, Iowa City, IA 52242, USA
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20
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Mamali I, Tatari MN, Micheva I, Lampropoulou M, Marmaras VJ. Apoptosis in medfly hemocytes is regulated during pupariation through FAK, Src, ERK, PI-3K p85a, and Akt survival signaling. J Cell Biochem 2007; 101:331-47. [PMID: 17177294 DOI: 10.1002/jcb.21175] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Focal adhesion kinase (FAK) and its downstream signaling targets are implicated in the process of apoptosis induced by external stimuli, in several mammalian systems. In this report, we demonstrate, that medfly (Ceratitis capitata) hemocytes do undergo apoptosis during larval development. In particular, we show using Western blot, ELISA and flow cytometry analysis, that FAK expression silencing in transfected by FAK double-stranded RNA (dsRNA) hemocytes, enhances twofold hemocyte apoptosis, by signaling through Src, MEK/ERK, and PI-3K/Akt signaling pathways. FAK expression silencing, in response to FAK dsRNA treatment, blocks partially the phosphorylation of its downstream targets. Pre-incubation of hemocytes, with specific inhibitors of FAK downstream signaling molecules, demonstrated that all these inhibitors reduced hemocyte viability and enhanced the magnitude of apoptosis about threefold. This data suggest that these pathways contribute to hemocyte survival and/or death during development. The expression and phosphorylation of FAK, Src, PI-3K p85a, Akt, and ERK signaling molecules appear to be dependent upon developmental stages. The expression and phosphorylation of the above signaling molecules, in annexin-positive and annexin-negative hemocytes is also distinct. The maximum expression and phosphorylation of FAK, Src, PI-3K p85a, Akt, and ERK appeared in annexin-positive hemocytes, in both early and late apoptotic hemocytes. The novel aspect of this report is based on the fact that hemocytes attempt to suppress apoptosis, by increasing the expression/phosphorylation of FAK and, hence its downstream targets signaling molecules Src, ERK, PI-3K p85a, and Akt. Evidently, the basic survival pathways among insects and mammals appear to remain unchanged, during evolution.
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Affiliation(s)
- Irene Mamali
- Department of Biology, University of Patras, Patras, Greece
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21
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Murakami S, Umetsu D, Maeyama Y, Sato M, Yoshida S, Tabata T. Focal adhesion kinase controls morphogenesis of the Drosophilaoptic stalk. Development 2007; 134:1539-48. [PMID: 17360775 DOI: 10.1242/dev.001529] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Photoreceptor cell axons (R axons) innervate optic ganglia in the Drosophila brain through the tubular optic stalk. This structure consists of surface glia (SG) and forms independently of R axon projection. In a screen for genes involved in optic stalk formation, we identified Fak56D encoding a Drosophila homolog of mammalian focal adhesion kinase (FAK). FAK is a main component of the focal adhesion signaling that regulates various cellular events, including cell migration and morphology. We show that Fak56D mutation causes severe disruption of the optic stalk structure. These phenotypes were completely rescued by Fak56D transgene expression in the SG cells but not in photoreceptor cells. Moreover, Fak56D genetically interacts with myospheroid, which encodes an integrin β subunit. In addition,we found that CdGAPr is also required for optic stalk formation and genetically interacts with Fak56D. CdGAPr encodes a GTPase-activating domain that is homologous to that of mammalian CdGAP, which functions in focal adhesion signaling. Hence the optic stalk is a simple monolayered structure that can serve as an ideal system for studying glial cell morphogenesis and the developmental role(s) of focal adhesion signaling.
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Affiliation(s)
- Satoshi Murakami
- Laboratory of Morphogenesis, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-Ku, Tokyo 113-0032, Japan
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22
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Corsi JM, Rouer E, Girault JA, Enslen H. Organization and post-transcriptional processing of focal adhesion kinase gene. BMC Genomics 2006; 7:198. [PMID: 16889663 PMCID: PMC1570463 DOI: 10.1186/1471-2164-7-198] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Accepted: 08/04/2006] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase critical for processes ranging from embryo development to cancer progression. Although isoforms with specific molecular and functional properties have been characterized in rodents and chicken, the organization of FAK gene throughout phylogeny and its potential to generate multiple isoforms are not well understood. Here, we study the phylogeny of FAK, the organization of its gene, and its post-transcriptional processing in rodents and human. RESULTS A single orthologue of FAK and the related PYK2 was found in non-vertebrate species. Gene duplication probably occurred in deuterostomes after the echinoderma embranchment, leading to the evolution of PYK2 with distinct properties. The amino acid sequence of FAK and PYK2 is conserved in their functional domains but not in their linker regions, with the absence of autophosphorylation site in C. elegans. Comparison of mouse and human FAK genes revealed the existence of multiple combinations of conserved and non-conserved 5'-untranslated exons in FAK transcripts suggesting a complex regulation of their expression. Four alternatively spliced coding exons (13, 14, 16, and 31), previously described in rodents, are highly conserved in vertebrates. Cis-regulatory elements known to regulate alternative splicing were found in conserved alternative exons of FAK or in the flanking introns. In contrast, other reported human variant exons were restricted to Homo sapiens, and, in some cases, other primates. Several of these non-conserved exons may correspond to transposable elements. The inclusion of conserved alternative exons was examined by RT-PCR in mouse and human brain during development. Inclusion of exons 14 and 16 peaked at the end of embryonic life, whereas inclusion of exon 13 increased steadily until adulthood. Study of various tissues showed that inclusion of these exons also occurred, independently from each other, in a tissue-specific fashion. CONCLUSION The alternative coding exons 13, 14, 16, and 31 are highly conserved in vertebrates and their inclusion in mRNA is tightly but independently regulated. These exons may therefore be crucial for FAK function in specific tissues or during development. Conversely pathological disturbance of the expression of FAK and of its isoforms could lead to abnormal cellular regulation.
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Affiliation(s)
- Jean-Marc Corsi
- Unité Mixte de Recherche-Santé (UMR-S) 536, Institut National de la Santé et de la Recherche Médicale (INSERM) F-75005, Paris, France; Université Pierre et Marie Curie-Paris 6, F-75005, Paris, France; Institut du Fer-à-Moulin, F-75005, Paris, France
| | - Evelyne Rouer
- Unité Mixte de Recherche-Santé (UMR-S) 536, Institut National de la Santé et de la Recherche Médicale (INSERM) F-75005, Paris, France; Université Pierre et Marie Curie-Paris 6, F-75005, Paris, France; Institut du Fer-à-Moulin, F-75005, Paris, France
| | - Jean-Antoine Girault
- Unité Mixte de Recherche-Santé (UMR-S) 536, Institut National de la Santé et de la Recherche Médicale (INSERM) F-75005, Paris, France; Université Pierre et Marie Curie-Paris 6, F-75005, Paris, France; Institut du Fer-à-Moulin, F-75005, Paris, France
| | - Hervé Enslen
- Unité Mixte de Recherche-Santé (UMR-S) 536, Institut National de la Santé et de la Recherche Médicale (INSERM) F-75005, Paris, France; Université Pierre et Marie Curie-Paris 6, F-75005, Paris, France; Institut du Fer-à-Moulin, F-75005, Paris, France
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23
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Grabbe C, Zervas CG, Hunter T, Brown NH, Palmer RH. Focal adhesion kinase is not required for integrin function or viability inDrosophila. Development 2004; 131:5795-805. [PMID: 15525665 DOI: 10.1242/dev.01462] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The mammalian focal adhesion kinase (FAK) family of non-receptor protein-tyrosine kinases has been implicated in controlling a multitude of cellular responses to the engagement of cell-surface integrins and G-protein-coupled receptors. The high level of sequence conservation between the mammalian proteins and the Drosophila homologue of FAK, Fak56,suggested that it would have similar functions. However, we show here that Drosophila Fak56 is not essential for integrin functions in adhesion,migration or signaling in vivo. Furthermore, animals lacking Fak56 are viable and fertile, demonstrating that Fak56 is not essential for other developmental or physiological functions. Despite this, overexpressed Fak56 is a potent inhibitor of integrins binding to the extracellular matrix, suggesting that Fak56 may play a subtle role in the negative regulation of integrin adhesion.
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Affiliation(s)
- Caroline Grabbe
- Umeå Center for Molecular Pathogenesis, Building 6L, Umeå University, Umeå, 901 87, Sweden
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24
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García MG, Toney SJ, Hille MB. Focal adhesion kinase (FAK) expression and phosphorylation in sea urchin embryos. Gene Expr Patterns 2004; 4:223-34. [PMID: 15161103 DOI: 10.1016/j.modgep.2003.08.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2003] [Revised: 08/13/2003] [Accepted: 08/19/2003] [Indexed: 11/20/2022]
Abstract
We have cloned three cDNA isoforms of focal adhesion kinase (FAK) from the sea urchin, Lytechinus variegatus. The sea urchin FAK is more closely related to FAK from other deuterostomes than from invertebrate protostomes or to cell adhesion kinase beta (CAKbeta/Pyk2/FAK2). FAK is expressed in all cells of sea urchin embryos by the 120-cell stage and strongly in blastulae. Phospho-FAK concentrates on basal surfaces of epithelial cells in early blastulae and occurs in syncytial cables of primary mesenchyme cells (PMC). Inhibition of FAK by constructs of FAK-related non-kinase delays blastocoel expansion and early PMC ingression. These results suggest that FAK has roles in cell adhesion and in the shape and integrity of the epithelial cells in sea urchin embryos.
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Affiliation(s)
- María Guadalupe García
- Department of Biology, University of Washington, Box 351800, Seattle, WA 98195-1800, USA
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25
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Schlaepfer DD, Mitra SK, Ilic D. Control of motile and invasive cell phenotypes by focal adhesion kinase. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1692:77-102. [PMID: 15246681 DOI: 10.1016/j.bbamcr.2004.04.008] [Citation(s) in RCA: 350] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Accepted: 04/08/2004] [Indexed: 01/09/2023]
Abstract
Cell motility is stimulated by extracellular stimuli and initiated by intracellular signaling proteins that localize to sites of cell contact with the extracellular matrix termed focal contacts. Focal adhesion kinase (FAK) is an intracellular protein-tyrosine kinase (PTK) that acts to regulate the cycle of focal contact formation and disassembly required for efficient cell movement. FAK is activated by a variety of cell surface receptors and transmits signals to a range of targets. Thus, FAK acts as an integrator of cell motility-associated signaling events. We will review the stimulatory and regulatory mechanisms of FAK activation, the different signaling connections of FAK that are mediated by a growing number of FAK-interacting proteins, and the modulation of FAK function by tyrosine and serine phosphorylation. We will also summarize findings with regard to FAK function in vertebrate and invertebrate development as well as recent insights into the mechanistic role(s) of FAK in promoting cell migration. As increased FAK expression and tyrosine phosphorylation have been correlated with the progression to an invasive cell phenotype, there is growing interest in elucidating the important FAK-related signaling connections promoting invasive tumor cell movement. To this end, we will discuss the effects of FAK inhibition via the dominant-negative expression of the FAK C-terminal domain termed FAK-related non-kinase (FRNK) and how these studies have uncovered a distinct role for FAK in promoting cell invasion that may differ from its role in promoting cell motility.
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Affiliation(s)
- David D Schlaepfer
- Department of Immunology, Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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26
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Englund C, Lorén CE, Grabbe C, Varshney GK, Deleuil F, Hallberg B, Palmer RH. Jeb signals through the Alk receptor tyrosine kinase to drive visceral muscle fusion. Nature 2003; 425:512-6. [PMID: 14523447 DOI: 10.1038/nature01950] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2003] [Accepted: 07/29/2003] [Indexed: 11/09/2022]
Abstract
The Drosophila melanogaster gene Anaplastic lymphoma kinase (Alk) is homologous to mammalian Alk, a member of the Alk/Ltk family of receptor tyrosine kinases (RTKs). We have previously shown that the Drosophila Alk RTK is crucial for visceral mesoderm development during early embryogenesis. Notably, observed Alk visceral mesoderm defects are highly reminiscent of the phenotype reported for the secreted molecule Jelly belly (Jeb). Here we show that Drosophila Alk is the receptor for Jeb in the developing visceral mesoderm, and that Jeb binding stimulates an Alk-driven, extracellular signal-regulated kinase-mediated signalling pathway, which results in the expression of the downstream gene duf (also known as kirre)--needed for muscle fusion. This new signal transduction pathway drives specification of the muscle founder cells, and the regulation of Duf expression by the Drosophila Alk RTK explains the visceral-mesoderm-specific muscle fusion defects observed in both Alk and jeb mutant animals.
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Affiliation(s)
- Camilla Englund
- Umeå Center for Molecular Pathogenesis, Umeå University, Umeå, S-901 87, Sweden
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27
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Abstract
The protein tyrosine kinase focal adhesion kinase (FAK) plays a prominent role in integrin signaling. FAK activation, demonstrated by an increase in phosphorylation of Tyr397 as well as other sites in the protein, is best understood in the context of the engagement of integrins at the cell surface. Activation of FAK results in recruitment of a number of SH2-domain- and SH3-domain-containing proteins, which mediate signaling to several downstream pathways. FAK-dependent activation of these pathways has been implicated in a diverse array of cellular processes, including cell migration, growth factor signaling, cell cycle progression and cell survival.
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Affiliation(s)
- J Thomas Parsons
- Department of Microbiology, University of Virginia Health System, Charlottesville, VA 22908, USA.
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28
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Enerly E, Larsson J, Lambertsson A. Reverse genetics in Drosophila: from sequence to phenotype using UAS-RNAi transgenic flies. Genesis 2002; 34:152-5. [PMID: 12324972 DOI: 10.1002/gene.10111] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Espen Enerly
- Institute of Biology, Division of Molecular Biology, University of Oslo, Oslo, Norway
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29
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Geisbrecht ER, Montell DJ. Myosin VI is required for E-cadherin-mediated border cell migration. Nat Cell Biol 2002; 4:616-20. [PMID: 12134162 DOI: 10.1038/ncb830] [Citation(s) in RCA: 174] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Myosin VI (MyoVI) is a pointed-end-directed, actin-based motor protein, and mutations in the gene result in disorganization of hair cell stereocilia and cause deafness in mice. MyoVI also localizes to the leading edges of growth-factor-stimulated fibroblast cells and has been suggested to be involved in cell motility. There has been no direct test of this hypothesis, however. Drosophila melanogaster MyoVI is expressed in a small group of migratory follicle cells, known as border cells. Here we show that depletion of MyoVI specifically from border cells severely inhibited their migration. Similar to MyoVI, E-cadherin is required for border cell migration. We found that E-cadherin and Armadillo (Arm, Drosophila beta-catenin) protein levels were specifically reduced in cells lacking MyoVI, whereas other proteins were not. In addition, MyoVI protein levels were reduced in cells lacking DE-cadherin or Arm. MyoVI and Arm co-immunoprecipitated from ovarian protein extracts. These data suggest that MyoVI is required for border cell migration where it stabilizes E-cadherin and Arm. Mutations in MyoVIIA, another unconventional myosin protein, also lead to deafness, and MyoVIIA interacts with E-cadherin through a membrane protein called vezatin. Multiple biochemical mechanisms may exist, therefore, for cadherins to associate with diverse unconventional myosins that are required for normal stereocilium formation or maintenance.
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Affiliation(s)
- Erika R Geisbrecht
- Department of Biological Chemistry, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205-2185, USA
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30
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Silver DL, Montell DJ. Paracrine signaling through the JAK/STAT pathway activates invasive behavior of ovarian epithelial cells in Drosophila. Cell 2001; 107:831-41. [PMID: 11779460 DOI: 10.1016/s0092-8674(01)00607-9] [Citation(s) in RCA: 240] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The JAK/STAT signaling pathway, renowned for its effects on cell proliferation and survival, is constitutively active in various human cancers, including ovarian. We have found that JAK and STAT are required to convert the border cells in the Drosophila ovary from stationary, epithelial cells to migratory, invasive cells. The ligand for this pathway, Unpaired (UPD), is expressed by two central cells within the migratory cell cluster. Mutations in upd or jak cause defects in migration and a reduction in the number of cells recruited to the cluster. Ectopic expression of either UPD or JAK is sufficient to induce extra epithelial cells to migrate. Thus, a localized signal activates the JAK/STAT pathway in neighboring epithelial cells, causing them to become invasive.
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Affiliation(s)
- D L Silver
- Department of Biological Chemistry, Johns Hopkins School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA
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31
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Abstract
Paxillin is a focal adhesion-associated, phosphotyrosine-containing protein that may play a role in several signaling pathways. Paxillin contains a number of motifs that mediate protein-protein interactions, including LD motifs, LIM domains, an SH3 domain-binding site and SH2 domain-binding sites. These motifs serve as docking sites for cytoskeletal proteins, tyrosine kinases, serine/threonine kinases, GTPase activating proteins and other adaptor proteins that recruit additional enzymes into complex with paxillin. Thus paxillin itself serves as a docking protein to recruit signaling molecules to a specific cellular compartment, the focal adhesions, and/or to recruit specific combinations of signaling molecules into a complex to coordinate downstream signaling. The biological function of paxillin coordinated signaling is likely to regulate cell spreading and motility.
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Affiliation(s)
- M D Schaller
- Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina, NC 27599, USA.
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32
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Schaller MD. Biochemical signals and biological responses elicited by the focal adhesion kinase. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1540:1-21. [PMID: 11476890 DOI: 10.1016/s0167-4889(01)00123-9] [Citation(s) in RCA: 419] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The focal adhesion kinase, FAK, is an important component of an integrin-dependent signaling pathway, which functions to transmit signals from the extracellular matrix into the cytoplasm. FAK is an essential gene product, since the fak-/- mouse exhibits embryonic lethality. A number of important biological processes, including cell motility and cell survival, are controlled by integrin-dependent signals and FAK has been implicated in regulating these processes. This review will focus upon recent findings providing insight into the mechanisms by which FAK transmits biochemical signals and elicits biological effects.
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Affiliation(s)
- M D Schaller
- Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill 27599, USA.
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33
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Lorén CE, Scully A, Grabbe C, Edeen PT, Thomas J, McKeown M, Hunter T, Palmer RH. Identification and characterization of DAlk: a novel Drosophila melanogaster RTK which drives ERK activation in vivo. Genes Cells 2001; 6:531-44. [PMID: 11442633 PMCID: PMC1975818 DOI: 10.1046/j.1365-2443.2001.00440.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The mammalian receptor protein tyrosine kinase (RTK), Anaplastic Lymphoma Kinase (ALK), was first described as the product of the t(2;5) chromosomal translocation found in non-Hodgkin's lymphoma. While the mechanism of ALK activation in non-Hodgkin's lymphoma has been examined, to date, no in vivo role for this orphan insulin receptor family RTK has been described. RESULTS We describe here a novel Drosophila melanogaster RTK, DAlk, which we have mapped to band 53 on the right arm of the second chromosome. Full-length DAlk cDNA encodes a phosphoprotein of 200 kDa, which shares homology not only with mammalian ALK but also with the orphan RTK LTK. Analysis of both mammalian and Drosophila ALK reveals that the ALK family of RTKs contains a newly identified MAM domain within their extracellular domains. Like its mammalian counterpart, DAlk appears to be expressed in the developing CNS by in situ analysis. However, in addition to expression of DAlk in the Drosophila brain, careful analysis reveals an additional early role for DAlk in the developing visceral mesoderm where its expression is coincident with activated ERK. CONCLUSION In this paper we describe a Drosophila melanogaster Alk RTK which is expressed in the developing embryonic mesoderm and CNS. Our data provide evidence for the existence of a DAlk RTK pathway in Drosophila. We show that ERK participates in this pathway, and that it is activated by DAlk in vivo. Expression patterns of dALK, together with activated ERK, suggest that DAlk fulfils the criteria of the missing RTK pathway, leading to ERK activation in the developing visceral mesoderm.
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Affiliation(s)
- Christina E. Lorén
- Umeå Center for Molecular Pathogenesis, Building 6L, Umeå University, S-901 87, Sweden
| | - Audra Scully
- The Salk Institute, Molecular Biology and Virology Laboratory, 10010 N. Torrey Pines Road, La Jolla, CA 2037-1099, USA
| | - Caroline Grabbe
- Umeå Center for Molecular Pathogenesis, Building 6L, Umeå University, S-901 87, Sweden
| | - Philip T. Edeen
- The Salk Institute, Molecular Biology and Virology Laboratory, 10010 N. Torrey Pines Road, La Jolla, CA 2037-1099, USA
| | - John Thomas
- The Salk Institute, Molecular Biology and Virology Laboratory, 10010 N. Torrey Pines Road, La Jolla, CA 2037-1099, USA
| | - Michael McKeown
- The Salk Institute, Molecular Biology and Virology Laboratory, 10010 N. Torrey Pines Road, La Jolla, CA 2037-1099, USA
| | - Tony Hunter
- The Salk Institute, Molecular Biology and Virology Laboratory, 10010 N. Torrey Pines Road, La Jolla, CA 2037-1099, USA
| | - Ruth H. Palmer
- Umeå Center for Molecular Pathogenesis, Building 6L, Umeå University, S-901 87, Sweden
- *Correspondence: E-mail:
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Metheniti A, Paraskevopoulou N, Lambropoulou M, Marmaras VJ. Involvement of FAK/Src complex in the processes of Escherichia coli phagocytosis by insect hemocytes. FEBS Lett 2001; 496:55-9. [PMID: 11343706 DOI: 10.1016/s0014-5793(01)02405-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Recently we demonstrated that lipopolysaccharide promotes activation of the Ras/mitogen-activated protein cascade in hemocytes and that phagocytosis of Escherichia coli by insect hemocytes is mediated by an integrin-dependent process [Foukas et al. (1998) J. Biol. Chem. 273, 14813--14818]. Here we report data concerning the focal adhesion kinase (FAK) tyrosine phosphorylation status in hemocytes in response to E. coli. We demonstrate that E. coli-triggering stimulates a significant increase in tyrosine phosphorylation of FAK in hemocytes. Furthermore, immunoblotting analysis using anti-Y397 demonstrated intense FAK activity at the Y397/SH2-binding site in hemocytes treated with E. coli. In addition, antibody-mediated inhibition of FAK and Src-kinase has been shown to abolish FAK phosphorylation and E. coli phagocytosis, indicating a specific role for the FAK/Src complex in the processes of promoting cell phagocytosis. These findings expand the known signaling functions of FAK and provide insight into signal transduction events associated with hemocyte phagocytosis in response to E. coli.
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Affiliation(s)
- A Metheniti
- Department of Biology, University of Patras, Patras 265 00, Greece
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35
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Zervas CG, Gregory SL, Brown NH. Drosophila integrin-linked kinase is required at sites of integrin adhesion to link the cytoskeleton to the plasma membrane. J Cell Biol 2001; 152:1007-18. [PMID: 11238456 PMCID: PMC2198807 DOI: 10.1083/jcb.152.5.1007] [Citation(s) in RCA: 238] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Integrin-linked kinase (ILK) was identified by its interaction with the cytoplasmic tail of human beta1 integrin and previous data suggest that ILK is a component of diverse signaling pathways, including integrin, Wnt, and protein kinase B. Here we show that the absence of ILK function in Drosophila causes defects similar to loss of integrin adhesion, but not similar to loss of these signaling pathways. ILK mutations cause embryonic lethality and defects in muscle attachment, and clones of cells lacking ILK in the adult wing fail to adhere, forming wing blisters. Consistent with this, an ILK-green fluorescent protein fusion protein colocalizes with the position-specific integrins at sites of integrin function: muscle attachment sites and the basal junctions of the wing epithelium. Surprisingly, mutations in the kinase domain shown to inactivate the kinase activity of human ILK do not show any phenotype in Drosophila, suggesting a kinase-independent function for ILK. The muscle detachment in ILK mutants is associated with detachment of the actin filaments from the muscle ends, unlike integrin mutants, in which the primary defect is detachment of the plasma membrane from the extracellular matrix. Our data suggest that ILK is a component of the structure linking the cytoskeleton and the plasma membrane at sites of integrin-mediated adhesion.
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Affiliation(s)
- Christos G. Zervas
- Wellcome/CRC Institute and Department of Anatomy, University of Cambridge, Cambridge CB2 1QR, United Kingdom
| | - Stephen L. Gregory
- Wellcome/CRC Institute and Department of Anatomy, University of Cambridge, Cambridge CB2 1QR, United Kingdom
| | - Nicholas H. Brown
- Wellcome/CRC Institute and Department of Anatomy, University of Cambridge, Cambridge CB2 1QR, United Kingdom
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Wheeler GN, Hynes RO. The cloning, genomic organization and expression of the focal contact protein paxillin in Drosophila. Gene 2001; 262:291-9. [PMID: 11179695 DOI: 10.1016/s0378-1119(00)00512-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Paxillin is a focal adhesion scaffolding protein, which has been proposed to play a role in focal adhesion dynamics. We have isolated a cDNA clone of the Drosophila homologue of paxillin. Comparison of the Drosophila paxillin sequence with those of vertebrate paxillins shows strong conservation of the LIM domains and LD repeats. Using the Drosophila genomic sequence we have identified two partial curated transcripts and deduced the structure of the paxillin gene. No homologues of other members of the paxillin family such as HIC-5 or leupaxin are to be found in the Drosophila genome. Surprisingly paxillin mRNA is expressed in a restricted pattern during embryogenesis. In particular it is strongly expressed in cells and tissues undergoing cell shape changes or cell migration. Many of the sites of expression are also known to be sites of integrin function or FAK expression. The data support a role for paxillin as an adapter and/or signaling protein during developmental processes involving integrin-mediated adhesion.
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Affiliation(s)
- G N Wheeler
- Howard Hughes Medical Institute and Center for Cancer Research, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Bai J, Uehara Y, Montell DJ. Regulation of invasive cell behavior by taiman, a Drosophila protein related to AIB1, a steroid receptor coactivator amplified in breast cancer. Cell 2000; 103:1047-58. [PMID: 11163181 DOI: 10.1016/s0092-8674(00)00208-7] [Citation(s) in RCA: 223] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Steroid hormones are key regulators of numerous physiological and developmental processes, including metastasis of breast and ovarian cancer. Here we report the identification of a Drosophila gene, named taiman, which encodes a steroid hormone receptor coactivator related to AIB1. Mutations in tai caused defects in the migration of specific follicle cells, the border cells, in the Drosophila ovary. Mutant cells exhibited abnormal accumulation of E-cadherin, beta-catenin, and focal adhesion kinase. TAI protein colocalized with the ecdysone receptor in vivo and augmented transcriptional activation by the ecdysone receptor in cultured cells. The finding of this type of coactivator required for cell motility suggests a novel role for steroid hormones, in stimulating invasive cell behavior, independent of effects on proliferation.
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Affiliation(s)
- J Bai
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA
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Parsons JT, Martin KH, Slack JK, Taylor JM, Weed SA. Focal adhesion kinase: a regulator of focal adhesion dynamics and cell movement. Oncogene 2000; 19:5606-13. [PMID: 11114741 DOI: 10.1038/sj.onc.1203877] [Citation(s) in RCA: 507] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Engagement of integrin receptors with extracellular ligands gives rise to the formation of complex multiprotein structures that link the ECM to the cytoplasmic actin cytoskeleton. These adhesive complexes are dynamic, often heterogeneous structures, varying in size and organization. In motile cells, sites of adhesion within filopodia and lamellipodia are relatively small and transient and are referred to as 'focal complexes,' whereas adhesions underlying the body of the cell and localized to the ends of actin stress fibers are referred to as 'focal adhesions'. Signal transduction through focal complexes and focal adhesions has been implicated in the regulation of a number of key cellular processes, including growth factor induced mitogenic signals, cell survival and cell locomotion. The formation and remodeling of focal contacts is a dynamic process under the regulation of protein tyrosine kinases and small GTPases of the Rho family. In this review, we consider the role of the focal complex associated protein tyrosine kinase, Focal Adhesion Kinase (FAK), in the regulation of cell movement with the emphasis on how FAK regulates the flow of signals from the ECM to the actin cytoskeleton.
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Affiliation(s)
- J T Parsons
- Department of Microbiology, Health Science Center, University of Virginia, Charlottesville, Virginia, VA 22908, USA
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Vial D, Okazaki H, Siraganian RP. The NH2-terminal region of focal adhesion kinase reconstitutes high affinity IgE receptor-induced secretion in mast cells. J Biol Chem 2000; 275:28269-75. [PMID: 10862765 DOI: 10.1074/jbc.m002842200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Focal adhesion kinase (FAK) is tyrosine-phosphorylated by adherence of cells and also by FcepsilonRI aggregation in RBL-2H3 mast cells. Using phosphorylation site-specific antibodies, we observed that FcepsilonRI activation in these cells led to an increase in FAK phosphorylation at the same tyrosine residues that are phosphorylated by integrin-induced activation. Previous studies in the 3B6 line, a FAK-deficient variant of the RBL-2H3 cells, suggest that FAK plays a role in FcepsilonRI-induced secretion. Stable cell lines expressing either full-length or truncated forms of FAK were isolated after transfection of the FAK-deficient 3B6 variant cells. The NH(2) domain of FAK, which lacks the enzymatic and the COOH-terminal regions, was sufficient to reconstitute secretion. The different truncated forms of FAK were still tyrosine-phosphorylated after FcepsilonRI aggregation. Therefore, the kinase domain and the COOH-terminal region are not essential for FcepsilonRI-induced tyrosine phosphorylation of FAK or for secretion. Taken together, our data demonstrate that the reconstitution of secretion is dissociated from FAK activation and that the NH(2)-terminal region of FAK is the only critical element that may play a role in FcepsilonRI-induced secretion by acting as an adaptor or linker molecule.
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Affiliation(s)
- D Vial
- Receptors and Signal Transduction Section, OIIB, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, USA.
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