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Narasimhan M, Johnson A, Prizak R, Kaufmann WA, Tan S, Casillas-Pérez B, Friml J. Evolutionarily unique mechanistic framework of clathrin-mediated endocytosis in plants. eLife 2020; 9:52067. [PMID: 31971511 PMCID: PMC7012609 DOI: 10.7554/elife.52067] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 01/22/2020] [Indexed: 12/13/2022] Open
Abstract
In plants, clathrin mediated endocytosis (CME) represents the major route for cargo internalisation from the cell surface. It has been assumed to operate in an evolutionary conserved manner as in yeast and animals. Here we report characterisation of ultrastructure, dynamics and mechanisms of plant CME as allowed by our advancement in electron microscopy and quantitative live imaging techniques. Arabidopsis CME appears to follow the constant curvature model and the bona fide CME population generates vesicles of a predominantly hexagonal-basket type; larger and with faster kinetics than in other models. Contrary to the existing paradigm, actin is dispensable for CME events at the plasma membrane but plays a unique role in collecting endocytic vesicles, sorting of internalised cargos and directional endosome movement that itself actively promote CME events. Internalized vesicles display a strongly delayed and sequential uncoating. These unique features highlight the independent evolution of the plant CME mechanism during the autonomous rise of multicellularity in eukaryotes.
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Affiliation(s)
| | - Alexander Johnson
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Roshan Prizak
- Institute of Science and Technology Austria, Klosterneuburg, Austria.,Institute of Biological and Chemical Systems - Biological Information Processing, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | | | - Shutang Tan
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | | | - Jiří Friml
- Institute of Science and Technology Austria, Klosterneuburg, Austria
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2
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Adamowski M, Narasimhan M, Kania U, Glanc M, De Jaeger G, Friml J. A Functional Study of AUXILIN-LIKE1 and 2, Two Putative Clathrin Uncoating Factors in Arabidopsis. THE PLANT CELL 2018; 30:700-716. [PMID: 29511054 PMCID: PMC5894831 DOI: 10.1105/tpc.17.00785] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 01/16/2018] [Accepted: 03/05/2018] [Indexed: 05/20/2023]
Abstract
Clathrin-mediated endocytosis (CME) is a cellular trafficking process in which cargoes and lipids are internalized from the plasma membrane into vesicles coated with clathrin and adaptor proteins. CME is essential for many developmental and physiological processes in plants, but its underlying mechanism is not well characterized compared with that in yeast and animal systems. Here, we searched for new factors involved in CME in Arabidopsis thaliana by performing tandem affinity purification of proteins that interact with clathrin light chain, a principal component of the clathrin coat. Among the confirmed interactors, we found two putative homologs of the clathrin-coat uncoating factor auxilin previously described in non-plant systems. Overexpression of AUXILIN-LIKE1 and AUXILIN-LIKE2 in Arabidopsis caused an arrest of seedling growth and development. This was concomitant with inhibited endocytosis due to blocking of clathrin recruitment after the initial step of adaptor protein binding to the plasma membrane. By contrast, auxilin-like1/2 loss-of-function lines did not present endocytosis-related developmental or cellular phenotypes under normal growth conditions. This work contributes to the ongoing characterization of the endocytotic machinery in plants and provides a robust tool for conditionally and specifically interfering with CME in Arabidopsis.
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Affiliation(s)
| | | | - Urszula Kania
- IST Austria, 3400 Klosterneuburg, Austria
- Ghent University, Department of Plant Biotechnology and Bioinformatics, 9052 Ghent, Belgium
- VIB Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Matouš Glanc
- IST Austria, 3400 Klosterneuburg, Austria
- Department of Experimental Plant Biology, Faculty of Science, Charles University, 12844 Prague, Czech Republic
| | - Geert De Jaeger
- Ghent University, Department of Plant Biotechnology and Bioinformatics, 9052 Ghent, Belgium
- VIB Center for Plant Systems Biology, 9052 Ghent, Belgium
| | - Jiří Friml
- IST Austria, 3400 Klosterneuburg, Austria
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3
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Park CJ, Wei T, Sharma R, Ronald PC. Overexpression of Rice Auxilin-Like Protein, XB21, Induces Necrotic Lesions, up-Regulates Endocytosis-Related Genes, and Confers Enhanced Resistance to Xanthomonas oryzae pv. oryzae. RICE (NEW YORK, N.Y.) 2017; 10:27. [PMID: 28577284 PMCID: PMC5457384 DOI: 10.1186/s12284-017-0166-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 05/24/2017] [Indexed: 05/29/2023]
Abstract
BACKGROUND The rice immune receptor XA21 confers resistance to the bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo). To elucidate the mechanism of XA21-mediated immunity, we previously performed a yeast two-hybrid screening for XA21 interactors and identified XA21 binding protein 21 (XB21). RESULTS Here, we report that XB21 is an auxilin-like protein predicted to function in clathrin-mediated endocytosis. We demonstrate an XA21/XB21 in vivo interaction using co-immunoprecipitation in rice. Overexpression of XB21 in rice variety Kitaake and a Kitaake transgenic line expressing XA21 confers a necrotic lesion phenotype and enhances resistance to Xoo. RNA sequencing reveals that XB21 overexpression results in the differential expression of 8735 genes (4939 genes up- and 3846 genes down-regulated) (≥2-folds, FDR ≤0.01). The up-regulated genes include those predicted to be involved in 'cell death' and 'vesicle-mediated transport'. CONCLUSION These results indicate that XB21 plays a role in the plant immune response and in regulation of cell death. The up-regulation of genes controlling 'vesicle-mediated transport' in XB21 overexpression lines is consistent with a functional role for XB21 as an auxilin.
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Affiliation(s)
- Chang-Jin Park
- Department of Plant Pathology and the Genome Center, University of California Davis, Davis, CA, 95616, USA
- Department of Bioresources Engineering and the Plant Engineering Research Institute, Sejong University, Seoul, 05006, Republic of Korea
| | - Tong Wei
- Department of Plant Pathology and the Genome Center, University of California Davis, Davis, CA, 95616, USA
- Feedstocks Division, Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Rita Sharma
- Department of Plant Pathology and the Genome Center, University of California Davis, Davis, CA, 95616, USA
- School of Computational & Integrative Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Pamela C Ronald
- Department of Plant Pathology and the Genome Center, University of California Davis, Davis, CA, 95616, USA.
- Feedstocks Division, Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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4
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Ebrahimie E, Moussavi Nik SH, Newman M, Van Der Hoek M, Lardelli M. The Zebrafish Equivalent of Alzheimer's Disease-Associated PRESENILIN Isoform PS2V Regulates Inflammatory and Other Responses to Hypoxic Stress. J Alzheimers Dis 2017; 52:581-608. [PMID: 27031468 DOI: 10.3233/jad-150678] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Dominant mutations in the PRESENILIN genes PSEN1 and PSEN2 cause familial Alzheimer's disease (fAD) that usually shows onset before 65 years of age. In contrast, genetic variation at the PSEN1 and PSEN2 loci does not appear to contribute to risk for the sporadic, late onset form of the disease (sAD), leading to doubts that these genes play a role in the majority of AD cases. However, a truncated isoform of PSEN2, PS2V, is upregulated in sAD brains and is induced by hypoxia and high cholesterol intake. PS2V can increase γ-secretase activity and suppress the unfolded protein response (UPR), but detailed analysis of its function has been hindered by lack of a suitable, genetically manipulable animal model since mice and rats lack this PRESENILIN isoform. We recently showed that zebrafish possess an isoform, PS1IV, that is cognate to human PS2V. Using an antisense morpholino oligonucleotide, we can block specifically the induction of PS1IV that normally occurs under hypoxia. Here, we exploit this ability to identify gene regulatory networks that are modulated by PS1IV. When PS1IV is absent under hypoxia-like conditions, we observe changes in expression of genes controlling inflammation (particularly sAD-associated IL1B and CCR5), vascular development, the UPR, protein synthesis, calcium homeostasis, catecholamine biosynthesis, TOR signaling, and cell proliferation. Our results imply an important role for PS2V in sAD as a component of a pathological mechanism that includes hypoxia/oxidative stress and support investigation of the role of PS2V in other diseases, including schizophrenia, when these are implicated in the pathology.
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Affiliation(s)
- Esmaeil Ebrahimie
- Department of Genetics and Evolution, School of Biological Sciences, University of Adelaide, Adelaide, Australia.,School of Information Technology and Mathematical Sciences, Division of Information Technology, Engineering and the Environment, University of South Australia, Adelaide, Australia.,School of Biological Sciences, Faculty of Science and Engineering, Flinders University, Adelaide, Australia
| | - Seyyed Hani Moussavi Nik
- Department of Genetics and Evolution, School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | - Morgan Newman
- Department of Genetics and Evolution, School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | - Mark Van Der Hoek
- Centre for Cancer Biology, SA Pathology, Frome Road, Adelaide, Australia
| | - Michael Lardelli
- Department of Genetics and Evolution, School of Biological Sciences, University of Adelaide, Adelaide, Australia
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Song L, He Y, Ou J, Zhao Y, Li R, Cheng J, Lin CH, Ho MS. Auxilin Underlies Progressive Locomotor Deficits and Dopaminergic Neuron Loss in a Drosophila Model of Parkinson’s Disease. Cell Rep 2017; 18:1132-1143. [DOI: 10.1016/j.celrep.2017.01.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 12/08/2016] [Accepted: 01/03/2017] [Indexed: 01/08/2023] Open
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Park BC, Yim YI, Zhao X, Olszewski MB, Eisenberg E, Greene LE. The clathrin-binding and J-domains of GAK support the uncoating and chaperoning of clathrin by Hsc70 in the brain. J Cell Sci 2015; 128:3811-21. [PMID: 26345367 DOI: 10.1242/jcs.171058] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 08/27/2015] [Indexed: 12/19/2022] Open
Abstract
Cyclin-G-associated kinase (GAK), the ubiquitously expressed J-domain protein, is essential for the chaperoning and uncoating of clathrin that is mediated by Hsc70 (also known as HSPA8). Adjacent to the C-terminal J-domain that binds to Hsc70, GAK has a clathrin-binding domain that is linked to an N-terminal kinase domain through a PTEN-like domain. Knocking out GAK in fibroblasts caused inhibition of clathrin-dependent trafficking, which was rescued by expressing a 62-kDa fragment of GAK, comprising just the clathrin-binding and J-domains. Expressing this fragment as a transgene in mice rescued the lethality and the histological defects caused by knocking out GAK in the liver or in the brain. Furthermore, when both GAK and auxilin (also known as DNAJC6), the neuronal-specific homolog of GAK, were knocked out in the brain, mice expressing the 62-kDa GAK fragment were viable, lived a normal life-span and had no major behavior abnormalities. However, these mice were about half the size of wild-type mice. Therefore, the PTEN-like domains of GAK and auxilin are not essential for Hsc70-dependent chaperoning and uncoating of clathrin, but depending on the tissue, these domains appear to increase the efficiency of these co-chaperones.
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Affiliation(s)
- Bum-Chan Park
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yang-In Yim
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xiaohong Zhao
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Maciej B Olszewski
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Evan Eisenberg
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lois E Greene
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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DeLuca GC, Kimball SM, Kolasinski J, Ramagopalan SV, Ebers GC. Review: the role of vitamin D in nervous system health and disease. Neuropathol Appl Neurobiol 2014; 39:458-84. [PMID: 23336971 DOI: 10.1111/nan.12020] [Citation(s) in RCA: 214] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 01/16/2013] [Indexed: 12/13/2022]
Abstract
Vitamin D and its metabolites have pleomorphic roles in both nervous system health and disease. Animal models have been paramount in contributing to our knowledge and understanding of the consequences of vitamin D deficiency on brain development and its implications for adult psychiatric and neurological diseases. The conflation of in vitro, ex vivo, and animal model data provide compelling evidence that vitamin D has a crucial role in proliferation, differentiation, neurotrophism, neuroprotection, neurotransmission, and neuroplasticity. Vitamin D exerts its biological function not only by influencing cellular processes directly, but also by influencing gene expression through vitamin D response elements. This review highlights the epidemiological, neuropathological, experimental and molecular genetic evidence implicating vitamin D as a candidate in influencing susceptibility to a number of psychiatric and neurological diseases. The strength of evidence varies for schizophrenia, autism, Parkinson's disease, amyotrophic lateral sclerosis, Alzheimer's disease, and is especially strong for multiple sclerosis.
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Affiliation(s)
- G C DeLuca
- Nuffield Department of Clinical Neurosciences (Clinical Neurology), University of Oxford, Oxford, UK.
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8
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Lin CH, Chen KH, Chen ML, Lin HI, Wu RM. Vitamin D receptor genetic variants and Parkinson's disease in a Taiwanese population. Neurobiol Aging 2013; 35:1212.e11-3. [PMID: 24239437 DOI: 10.1016/j.neurobiolaging.2013.10.094] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 10/03/2013] [Accepted: 10/26/2013] [Indexed: 01/11/2023]
Abstract
Patients with Parkinson's disease (PD) have hypovitaminosis D status and genetic variants of vitamin D receptor (VDR) gene are recently shown to be associated with PD in a large-scale genome-wide association study in a Caucasian population. Few studies examined VDR genetic variants in large-scale Asian patients with PD. We therefore genotyped 6 VDR genetic variants in a total of 1492 Taiwanese subjects, including 700 patients with PD and 792 age and/or gender matched control subjects. We did not observe any significant associations between the studied genetic variants of VDR and the risk of PD. Our data suggest that genetic variations of the VDR gene did not play a major role in a Taiwanese PD population. Further studies of VDR and its interaction with serum vitamin D levels are warranted to clarify the potential role of vitamin D in PD pathogenesis.
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Affiliation(s)
- Chin-Hsien Lin
- Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Kai-Hsiang Chen
- Department of Neurology, National Taiwan University Hospital, Hsin Chu Branch, Hsin Chu, Taiwan
| | - Meng-Ling Chen
- Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan; Institute of Zoology, National Taiwan University, Taipei, Taiwan
| | - Han-I Lin
- Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Ruey-Meei Wu
- Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan.
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Rusiniak ME, Kunnev D, Freeland A, Cady GK, Pruitt SC. Mcm2 deficiency results in short deletions allowing high resolution identification of genes contributing to lymphoblastic lymphoma. Oncogene 2011; 31:4034-44. [PMID: 22158038 PMCID: PMC3309111 DOI: 10.1038/onc.2011.566] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mini-chromosome maintenance (Mcm) proteins are part of the replication licensing complex that is loaded onto chromatin during the G1-phase of the cell cycle and required for initiation of DNA replication in the subsequent S-phase. Mcm proteins are typically loaded in excess of the number of locations that are utilized during S-phase. Nonetheless, partial depletion of Mcm proteins leads to cancers and stem cell deficiencies. Mcm2 deficient mice, on a 129Sv genetic background, display a high rate of thymic lymphoblastic lymphoma. Here array comparative genomic hybridization (aCGH) is utilized to characterize the genetic damage accruing in these tumors. The predominant events are deletions averaging less than 0.5 Mb, considerably shorter than observed in prior studies using alternative mouse lymphoma models or human tumors. Such deletions facilitate identification of specific genes and pathways responsible for the tumors. Mutations in many genes that have been implicated in human lymphomas are recapitulated in this mouse model. These features, and the fact that the mutation underlying the accelerated genetic damage does not target a specific gene or pathway a priori, are valuable features of this mouse model for identification of tumor suppressor genes. Genes affected in all tumors include Pten, Tcfe2a, Mbd3 and Setd1b. Notch1 and additional genes are affected in subsets of tumors. The high frequency of relatively short deletions is consistent with elevated recombination between nearby stalled replication forks in Mcm2 deficient mice.
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Affiliation(s)
- M E Rusiniak
- Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, Buffalo, NY 14263, USA
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Banks SML, Cho B, Eun SH, Lee JH, Windler SL, Xie X, Bilder D, Fischer JA. The functions of auxilin and Rab11 in Drosophila suggest that the fundamental role of ligand endocytosis in notch signaling cells is not recycling. PLoS One 2011; 6:e18259. [PMID: 21448287 PMCID: PMC3063240 DOI: 10.1371/journal.pone.0018259] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 02/23/2011] [Indexed: 12/03/2022] Open
Abstract
Notch signaling requires ligand internalization by the signal sending cells. Two endocytic proteins, epsin and auxilin, are essential for ligand internalization and signaling. Epsin promotes clathrin-coated vesicle formation, and auxilin uncoats clathrin from newly internalized vesicles. Two hypotheses have been advanced to explain the requirement for ligand endocytosis. One idea is that after ligand/receptor binding, ligand endocytosis leads to receptor activation by pulling on the receptor, which either exposes a cleavage site on the extracellular domain, or dissociates two receptor subunits. Alternatively, ligand internalization prior to receptor binding, followed by trafficking through an endosomal pathway and recycling to the plasma membrane may enable ligand activation. Activation could mean ligand modification or ligand transcytosis to a membrane environment conducive to signaling. A key piece of evidence supporting the recycling model is the requirement in signaling cells for Rab11, which encodes a GTPase critical for endosomal recycling. Here, we use Drosophila Rab11 and auxilin mutants to test the ligand recycling hypothesis. First, we find that Rab11 is dispensable for several Notch signaling events in the eye disc. Second, we find that Drosophila female germline cells, the one cell type known to signal without clathrin, also do not require auxilin to signal. Third, we find that much of the requirement for auxilin in Notch signaling was bypassed by overexpression of both clathrin heavy chain and epsin. Thus, the main role of auxilin in Notch signaling is not to produce uncoated ligand-containing vesicles, but to maintain the pool of free clathrin. Taken together, these results argue strongly that at least in some cell types, the primary function of Notch ligand endocytosis is not for ligand recycling.
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Affiliation(s)
- Susan M. L. Banks
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Bomsoo Cho
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Suk Ho Eun
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Ji-Hoon Lee
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - Sarah L. Windler
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Xuanhua Xie
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
| | - David Bilder
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Janice A. Fischer
- Section of Molecular Cell and Developmental Biology and Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America
- * E-mail:
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Seebald JL, Szeto DP. Zebrafish eve1 regulates the lateral and ventral fates of mesodermal progenitor cells at the onset of gastrulation. Dev Biol 2011; 349:78-89. [DOI: 10.1016/j.ydbio.2010.10.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 10/01/2010] [Accepted: 10/05/2010] [Indexed: 12/13/2022]
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12
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Susa M, Choy E, Liu X, Schwab J, Hornicek FJ, Mankin H, Duan Z. Cyclin G-associated kinase is necessary for osteosarcoma cell proliferation and receptor trafficking. Mol Cancer Ther 2010; 9:3342-50. [PMID: 20881269 DOI: 10.1158/1535-7163.mct-10-0637] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Osteosarcoma is the most frequent primary malignant bone tumor among the children. The advent of neoadjuvant chemotherapy significantly improved the prognosis of patients with osteosarcoma in the 1980s, but it has since plateaued in the past decades. Recently, one of the most researched areas in sarcoma treatment is tyrosine kinases. Here, we describe research on a serine/threonine kinase, cyclin G-associated kinase (GAK), which has not been reported in osteosarcoma previously. In this study, a lentiviral based human shRNA library was utilized to screen for kinases in KHOS and U-2OS osteosarcoma cells. The expression of GAK was examined in osteosarcoma and the effect on cell proliferation was analyzed by GAK siRNA knockdown. The level of GAK expression and its correlation to prognosis was analyzed in osteosarcoma tissue microarray. The effect of GAK depletion on insulin-like growth factor and epidermal growth factor receptor-mediated signal transduction was analyzed by Western blot. We observed that GAK was overexpressed in both osteosarcoma cell lines and tissue samples when compared with human osteoblasts. GAK knockdown by siRNA decreased cell proliferation in both drug-sensitive and multidrug-resistant osteosarcoma cell lines. Immunohistochemistry of osteosarcoma tissue microarray revealed that overexpression of GAK was associated with poor prognosis. Finally, knockdown of GAK resulted in alterations of receptor trafficking and several downstream proteins. In conclusion, our results suggest that osteosarcoma cell proliferation and survival are dependent on GAK. These findings may lead to the development of new therapeutic options for osteosarcoma.
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Affiliation(s)
- Michiro Susa
- Department of Orthopaedic Surgery, and SarcomaBiology Laboratory, Center for Sarcoma and Connective Tissue Oncology, Massachusetts General Hospital, Boston, MA 02114, USA
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