1
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Sudo H, Nakajima K. The mitotic tensegrity guardian tau protects mammary epithelia from katanin-like1-induced aneuploidy. Oncotarget 2016; 7:53712-53734. [PMID: 27447563 PMCID: PMC5288216 DOI: 10.18632/oncotarget.10728] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 06/16/2016] [Indexed: 11/25/2022] Open
Abstract
The microtubule associated-protein tau has been identified as an effective positive prognostic indicator in breast cancer. To explore the physiological function of tau in early carcinogenesis, endogenous tau was knocked down in primary cultured human mammary epithelial cells. This resulted in chromosome-bridging during anaphase followed by micronucleation, both of which were suppressed by a further katanin-like1 knockdown. We also detected that the exogenously expressed katanin-like1 induction of cellular transformation is prevented by exogenous tau in rat fibroblasts. The mutant katanin-like1 (L123V) identified in breast cancer showed an increase in this transformation capacity as well as microtubule severing activity resistant to tau. The tau knockdown resulted in a loss of the kinetochore fibers on which tau is normally localized. This physical fragility was also observed in isolated tau-knockdown mitotic spindles, supporting the relevance of microtubule damage to the onset of transformation. The karyotyping of tau-knockdown cells showed increased frequency of loss of one X chromosome, further suggesting the involvement of tau in breast tumorigenesis. We propose that tau may contribute to tumor progression by protecting spindle microtubules from excess severing by katanin-like1. We also present data indicating that the microtubule-binding octapeptide NAP is a candidate modifier against the tau deficiency in tumor cells.
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Affiliation(s)
- Haruka Sudo
- Department of Biochemistry, The Nippon Dental University School of Life Dentistry at Tokyo, Chiyoda-ku, Tokyo 102-8159, Japan.,Department of Anatomy, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan
| | - Kazunori Nakajima
- Department of Anatomy, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan
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2
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Puts CF, Lenoir G, Krijgsveld J, Williamson P, Holthuis JCM. A P4-ATPase Protein Interaction Network Reveals a Link between Aminophospholipid Transport and Phosphoinositide Metabolism. J Proteome Res 2009; 9:833-42. [DOI: 10.1021/pr900743b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Catheleyne F. Puts
- Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, and Biomolecular Mass Spectometry and Proteomics Group, Bijvoet Center and Netherlands Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands and Department of Biology, Amherst College, Amherst, Massachusetts 01002
| | - Guillaume Lenoir
- Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, and Biomolecular Mass Spectometry and Proteomics Group, Bijvoet Center and Netherlands Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands and Department of Biology, Amherst College, Amherst, Massachusetts 01002
| | - Jeroen Krijgsveld
- Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, and Biomolecular Mass Spectometry and Proteomics Group, Bijvoet Center and Netherlands Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands and Department of Biology, Amherst College, Amherst, Massachusetts 01002
| | - Patrick Williamson
- Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, and Biomolecular Mass Spectometry and Proteomics Group, Bijvoet Center and Netherlands Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands and Department of Biology, Amherst College, Amherst, Massachusetts 01002
| | - Joost C. M. Holthuis
- Membrane Enzymology, Bijvoet Center and Institute of Biomembranes, and Biomolecular Mass Spectometry and Proteomics Group, Bijvoet Center and Netherlands Proteomics Center, Utrecht University, 3584 CH Utrecht, The Netherlands and Department of Biology, Amherst College, Amherst, Massachusetts 01002
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3
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Lim J, Lu KP. Pinning down phosphorylated tau and tauopathies. Biochim Biophys Acta Mol Basis Dis 2005; 1739:311-22. [PMID: 15615648 DOI: 10.1016/j.bbadis.2004.10.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2004] [Revised: 09/09/2004] [Accepted: 10/07/2004] [Indexed: 12/23/2022]
Abstract
Neurofibrillary tangles (NFTs) are prominent neuronal lesions in a large subset of neurodegenerative diseases, including Alzheimer's disease (AD). NFTs are mainly composed of insoluble Tau that is hyperphosphorylated on many serine or threonine residues preceding proline (pSer/Thr-Pro). Tau hyperphosphorylation abolishes its biological function to bind microtubules and promotes microtubule assembly and precedes neurodegeneration. Not much is known about how tau is further regulated following phosphorylation. Notably, we have recently shown that phosphorylated Ser/Thr-Pro motifs exist in two distinct conformations. The conversion between two conformations in some proteins is catalyzed by the prolyl isomerase Pin1. Pin1 binds to tau phosphorylated specifically on the Thr231-Pro site and probably catalyzes cis/trans isomerization of pSer/Thr-Pro motif(s), thereby inducing conformational changes in tau. Such conformational changes can directly restore the ability of phosphorylated Tau to bind microtubules and promote microtubule assembly and/or facilitate tau dephosphorylation by its phosphatase PP2A, as PP2A activity is conformation-specific. Furthermore, Pin1 expression inversely correlates with the predicted neuronal vulnerability in normally aged brain and also with actual neurofibrillary degeneration in AD brain. Moreover, deletion of the gene encoding Pin1 in mice causes progressive age-dependent neuropathy characterized by motor and behavioral deficits, tau hyperphosphorylation, tau filament formation and neuronal degeneration. Distinct from all other mouse models where transgenic overexpression of specific proteins elicits tau-related pathologies, Pin1 is the first protein whose depletion causes age-dependent neurodegeneration and tau pathologies. Thus, Pin1 is pivotal in maintaining normal neuronal function and preventing age-dependent neurodegeneration. This could represent a promising interventive target to prevent neurodegenerative diseases.
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Affiliation(s)
- Jormay Lim
- Cancer Biology Program Division of Hematology/Oncology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, NRB 1030K, Boston, MA 02215, USA.
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4
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Arikan MC, Memmott J, Broderick JA, Lafyatis R, Screaton G, Stamm S, Andreadis A. Modulation of the membrane-binding projection domain of tau protein: splicing regulation of exon 3. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2002; 101:109-21. [PMID: 12007838 DOI: 10.1016/s0169-328x(02)00178-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Tau is a microtubule-associated protein whose transcript undergoes complex regulated splicing in the mammalian nervous system. The N-terminal domain of the protein interacts with the axonal membrane, and is modulated by differential inclusion of exons 2 and 3. These two tau exons are alternatively spliced cassettes, in which exon 3 never appears independently of exon 2. Previous work with tau minigene constructs indicated that exon 3 is intrinsically suboptimal and its primary regulator is a weak branch point. In this study, we confirm the role of the weak branch point in the regulation of exon 3 but also show that the exon is additionally regulated by a combination of exonic enhancers and silencers. Furthermore, we demonstrate that known splicing regulators affect the ratio of exon 3 isoforms, Lastly, we tentatively pinpoint the site of action of several splicing factors which regulate tau exon 3.
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Affiliation(s)
- Meltem Cevik Arikan
- Department of Biomedical Sciences, E.K. Shriver Center for Mental Retardation, Waltham, MA 02454, USA
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5
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Walsh EP, Lamont DJ, Beattie KA, Stark MJR. Novel interactions of Saccharomyces cerevisiae type 1 protein phosphatase identified by single-step affinity purification and mass spectrometry. Biochemistry 2002; 41:2409-20. [PMID: 11841235 DOI: 10.1021/bi015815e] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The catalytic subunit of Saccharomyces cerevisiae type 1 protein phosphatase (PP1(C)) is encoded by the essential gene GLC7 and is involved in regulating diverse cellular processes. To identify potential regulatory or targeting subunits of yeast PP1(C), we tagged Glc7p at its amino terminus with protein A and affinity-purified Glc7p protein complexes from yeast. The purified proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and identified by peptide mass fingerprint analysis using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. To confirm the accuracy of our identifications, peptides from some of the proteins were also sequenced using high-performance liquid chromatography (HPLC) coupled to tandem mass spectrometry. Only four of the Glc7p-associated proteins that we identified (Mhp1p, Bni4p, Ref2p, and Sds22p) have previously been shown to interact with Glc7p, and multiple components of the CPF (cleavage and polyadenylation factor) complex involved in messenger RNA 3'-end processing were present as major components in the Glc7p-associated protein fraction. To confirm the interaction of Glc7p with this complex, we used the same approach to purify and characterize the components of the yeast CPF complex using protein A-tagged Pta1p. Six known components of the yeast (CPF) complex, together with Glc7p, were identified among the Pta1p-associated polypeptides using peptide mass fingerprint analysis. Thus Glc7p is a novel component of the CPF complex and may therefore be involved regulating mRNA 3'-end processing.
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Affiliation(s)
- Edmund P Walsh
- School of Life Sciences Biocentre, University of Dundee, Dundee DD1 5EH, UK
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6
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Goedert M, Spillantini MG, Serpell LC, Berriman J, Smith MJ, Jakes R, Crowther RA. From genetics to pathology: tau and alpha-synuclein assemblies in neurodegenerative diseases. Philos Trans R Soc Lond B Biol Sci 2001; 356:213-27. [PMID: 11260802 PMCID: PMC1088427 DOI: 10.1098/rstb.2000.0767] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The most common degenerative diseases of the human brain are characterized by the presence of abnormal filamentous inclusions in affected nerve cells and glial cells. These diseases can be grouped into two classes, based on the identity of the major proteinaceous components of the filamentous assemblies. The filaments are made of either the microtubule-associated protein tau or the protein alpha-synuclein. Importantly, the discovery of mutations in the tau gene in familial forms of frontotemporal dementia and of mutations in the alpha-synuclein gene in familial forms of Parkinson's disease has established that dysfunction of tau protein and alpha-synuclein can cause neurodegeneration.
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Affiliation(s)
- M Goedert
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK.
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7
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RayChaudhuri D. ZipA is a MAP-Tau homolog and is essential for structural integrity of the cytokinetic FtsZ ring during bacterial cell division. EMBO J 1999; 18:2372-83. [PMID: 10228152 PMCID: PMC1171320 DOI: 10.1093/emboj/18.9.2372] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The first visible event in prokaryotic cell division is the assembly of the soluble, tubulin-like FtsZ GTPase into a membrane-associated cytokinetic ring that defines the division plane in bacterial and archaeal cells. In the temperature-sensitive ftsZ84 mutant of Escherichia coli, this ring assembly is impaired at the restrictive temperature causing lethal cell filamentation. Here I present genetic and morphological evidence that a 2-fold higher dosage of the division gene zipA suppresses thermosensitivity of the ftsZ84 mutant by stabilizing the labile FtsZ84 ring structure in vivo. I demonstrate that purified ZipA promotes and stabilizes protofilament assembly of both FtsZ and FtsZ84 in vitro and cosediments with the protofilaments. Furthermore, ZipA organizes FtsZ protofilaments into arrays of long bundles or sheets that probably represent the physiological organization of the FtsZ ring in bacterial cells. The N-terminal cytoplasmic domain of membrane-anchored ZipA contains sequence elements that resemble the microtubule-binding signature motifs in eukaryotic Tau, MAP2 and MAP4 proteins. It is postulated that the MAP-Tau-homologous motifs in ZipA mediate its binding to FtsZ, and that FtsZ-ZipA interaction represents an ancient prototype of the protein-protein interaction that enables MAPs to suppress microtubule catastrophe and/or to promote rescue.
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Affiliation(s)
- D RayChaudhuri
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA.
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8
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Goedert M. Neurofibrillary pathology of Alzheimer's disease and other tauopathies. PROGRESS IN BRAIN RESEARCH 1999; 117:287-306. [PMID: 9932415 DOI: 10.1016/s0079-6123(08)64022-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- M Goedert
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.
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9
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Irminger-Finger I, Soriano JV, Vaudan G, Montesano R, Sappino AP. In vitro repression of Brca1-associated RING domain gene, Bard1, induces phenotypic changes in mammary epithelial cells. J Biophys Biochem Cytol 1998; 143:1329-39. [PMID: 9832560 PMCID: PMC2133073 DOI: 10.1083/jcb.143.5.1329] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
BRCA1-associated RING domain (BARD1) was identified as a protein interacting with the breast cancer gene product BRCA1. The identification of tumorigenic missense mutations within BRCA1 that impair the formation of BARD1-BRCA1 complexes, and of BARD1 mutations in breast carcinomas, sustain the view that BARD1 is involved in BRCA1-mediated tumor suppression. We have cloned the murine Bard1 gene and determined that its expression in different tissues correlates with the expression profile of Brca1. To investigate the function of Bard1, we have reduced Bard1 gene expression in TAC-2 cells, a murine mammary epithelial cell line that retains morphogenetic properties characteristic of normal breast epithelium. Partial repression of Bard1, achieved by the transfection of TAC-2 cells with plasmids constitutively expressing ribozymes or antisense RNAs, resulted in marked phenotypic changes, consisting of altered cell shape, increased cell size, high frequency of multinucleated cells, and aberrant cell cycle progression. Furthermore, Bard1-repressed cell clones overcame contact inhibition of cell proliferation when grown in monolayer cultures and lost the capacity to form luminal structures in three-dimensional collagen gels. These results demonstrate that Bard1 repression induces complex changes in mammary epithelial cell properties which are suggestive of a premalignant phenotype.
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Affiliation(s)
- I Irminger-Finger
- Laboratory of Biology of Aging and Department of Geriatrics, University of Geneva, Switzerland.
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10
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Abstract
The presence of intervening sequences or introns in eukaryotic genes has been known for more than 20 years, and the mechanisms underlying RNA splicing have been studied in depth both genetically and biochemically. In recent years, however, an increasing number of bacterial genes have been introduced into higher eukaryotes as important tools for genetic studies. Their gene products are frequently used as an indirect measure for cell type-specific promoter activity, as, for example, in the case of chloramphenicol acetyl transferase (CAT assay) or beta-galactosidase. Here we show that RNA splicing of two prokaryotic genes encoding site-specific DNA recombinases occurs in eukaryotic cells. In one case, splicing is only observed after treatment of cells with the cytokine alpha interferon. We further demonstrate that mutating an intragenic donor splice site in a bacterial gene apparently activates a second, alternative splicing pathway. In conjunction with previous reports, our findings should also be regarded as a warning that splicing of bacterial genes in higher eukaryotes is a more common phenomenon than presently recognized, which may be difficult to overcome and may cause problems in the interpretation of experimental results.
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Affiliation(s)
- E Lorbach
- Institute of Genetics, University of Cologne, Germany
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11
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Abstract
Microtubules (MTs) serve as tracks for cellular transport, and regulate cell shape and polarity. Rapid transitions between stable and dynamic forms of MTs are central to these processes. This dynamic instability is regulated by a number of cellular factors, including the structural MT-associated proteins (MAPs), which in turn are regulated by phosphorylation. MT-affinity-regulating kinases (MARKs) are novel mammalian serine/threonine kinases that phosphorylate the tubulin-binding domain of MAPs and thereby cause their detachment from MTs and increased MT dynamics. Molecular cloning of MARKs revealed a family of four closely related protein kinases that share homology with genes from the nematode Caenorhabditis elegans and fission yeast that are involved in the generation of cell shape and polarity. Hence, MARKs might play a role in the regulation of MT stability during morphogenesis.
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Affiliation(s)
- G Drewes
- Max-Planck-Unit for Structural Molecular Biology, Hamburg, Germany
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12
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Radcliffe P, Hirata D, Childs D, Vardy L, Toda T. Identification of novel temperature-sensitive lethal alleles in essential beta-tubulin and nonessential alpha 2-tubulin genes as fission yeast polarity mutants. Mol Biol Cell 1998; 9:1757-71. [PMID: 9658169 PMCID: PMC25415 DOI: 10.1091/mbc.9.7.1757] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We have screened for temperature-sensitive (ts) fission yeast mutants with altered polarity (alp1-15). Genetic analysis indicates that alp2 is allelic to atb2 (one of two alpha-tubulin genes) and alp12 to nda3 (the single beta-tubulin gene). atb2(+) is nonessential, and the ts atb2 mutations we have isolated are dominant as expected. We sequenced two alleles of ts atb2 and one allele of ts nda3. In the ts atb2 mutants, the mutated residues (G246D and C356Y) are found at the longitudinal interface between alpha/beta-heterodimers, whereas in ts nda3 the mutated residue (Y422H) is situated in the domain located on the outer surface of the microtubule. The ts nda3 mutant is highly sensitive to altered gene dosage of atb2(+); overexpression of atb2(+) lowers the restrictive temperature, and, conversely, deletion rescues ts. Phenotypic analysis shows that contrary to undergoing mitotic arrest with high viability via the spindle assembly checkpoint as expected, ts nda3 mutants execute cytokinesis and septation and lose viability. Therefore, it appears that the ts nda3 mutant becomes temperature lethal because of irreversible progression through the cell cycle in the absence of activating the spindle assembly checkpoint pathway.
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Affiliation(s)
- P Radcliffe
- Laboratory of Cell Regulation, Imperial Cancer Research Fund, London WC2A 3PX, United Kingdom
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13
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Poorkaj P, Bird TD, Wijsman E, Nemens E, Garruto RM, Anderson L, Andreadis A, Wiederholt WC, Raskind M, Schellenberg GD. Tau is a candidate gene for chromosome 17 frontotemporal dementia. Ann Neurol 1998; 43:815-25. [PMID: 9629852 DOI: 10.1002/ana.410430617] [Citation(s) in RCA: 957] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Frontotemporal dementia with parkinsonism, chromosome 17 type (FTDP-17), a recently defined disease entity, is clinically characterized by personality changes sometimes associated with psychosis, hyperorality, and diminished speech output, disturbed executive function and nonfluent aphasia, bradykinesia, and rigidity. Neuropathological changes include frontotemporal atrophy often associated with atrophy of the basal ganglia, substantia nigra, and amygdala. Neurofibrillary tangles (NFTs) are seen in some but not all families. Inheritance is autosomal dominant and the gene has been regionally localized to 17q21-22 in a 2- to 4-centimorgan (cM) region flanked by markers D17S800 and D17S791. The gene for tau, the primary component of NFTs, is located in the same region of chromosome 17. Tau was evaluated as a candidate gene. Physical mapping studies place tau within 2 megabases or less of D17S791, but it is probably outside the D17S800-D17S791 FTDP-17 interval. DNA sequence analysis of tau coding regions in affected subjects from two FTDP-17 families revealed nine DNA sequence variants, eight of which were also identified in controls and are thus polymorphisms. A ninth variant (Val279Met) was found in one FTDP-17 family but not in the second FTDP-17 family. Three lines of evidence indicate that the Val279Met change is an FTDP-17 causative mutation. First, the mutation site is highly conserved, and a normal valine is found at this position in all three tau interrepeat sequences and in other microtubule associated protein tau homologues. Second, the mutation co-segregates with the disease in family A. Third, the mutation is not found in normal controls.
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Affiliation(s)
- P Poorkaj
- Geriatric Research Education Clinical Center, Veterans Affairs Puget Sound Health Care System, Division of Gerontology, University of Washington, Seattle 98108, USA
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14
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Wigge PA, Jensen ON, Holmes S, Souès S, Mann M, Kilmartin JV. Analysis of the Saccharomyces spindle pole by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. J Cell Biol 1998; 141:967-77. [PMID: 9585415 PMCID: PMC2132767 DOI: 10.1083/jcb.141.4.967] [Citation(s) in RCA: 262] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
A highly enriched spindle pole preparation was prepared from budding yeast and fractionated by SDS gel electrophoresis. Forty-five of the gel bands that appeared enriched in this fraction were analyzed by high-mass accuracy matrix-assisted laser desorption/ ionization (MALDI) peptide mass mapping combined with sequence database searching. This identified twelve of the known spindle pole components and an additional eleven gene products that had not previously been localized to the spindle pole. Immunoelectron microscopy localized eight of these components to different parts of the spindle. One of the gene products, Ndc80p, shows homology to human HEC protein (Chen, Y., D.J. Riley, P-L. Chen, and W-H. Lee. 1997. Mol. Cell Biol. 17:6049-6056) and temperature-sensitive mutants show defects in chromosome segregation. This is the first report of the identification of the components of a large cellular organelle by MALDI peptide mapping alone.
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MESH Headings
- Amino Acid Sequence
- Chromosomes, Fungal/physiology
- Chromosomes, Fungal/ultrastructure
- Cloning, Molecular
- Cytoskeletal Proteins
- Databases, Factual
- Humans
- Kinetochores
- Microscopy, Immunoelectron
- Models, Biological
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Neoplasm Proteins/chemistry
- Nuclear Proteins/analysis
- Nuclear Proteins/biosynthesis
- Nuclear Proteins/chemistry
- Peptide Library
- Peptide Mapping
- Saccharomyces cerevisiae/physiology
- Saccharomyces cerevisiae/ultrastructure
- Saccharomyces cerevisiae Proteins
- Schizosaccharomyces
- Sequence Alignment
- Sequence Homology, Amino Acid
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods
- Spindle Apparatus/physiology
- Spindle Apparatus/ultrastructure
- Temperature
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Affiliation(s)
- P A Wigge
- Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge CB2 2QH, United Kingdom
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15
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Abstract
The polymerization dynamics of microtubules are central to their biological functions. Polymerization dynamics allow microtubules to adopt spatial arrangements that can change rapidly in response to cellular needs and, in some cases, to perform mechanical work. Microtubules utilize the energy of GTP hydrolysis to fuel a unique polymerization mechanism termed dynamic instability. In this review, we first describe progress toward understanding the mechanism of dynamic instability of pure tubulin and then discuss the function and regulation of microtubule dynamic instability in living cells.
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Affiliation(s)
- A Desai
- Department of Biochemistry and Biophysics, University of California, San Francisco 94143, USA.
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16
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Schwartz K, Richards K, Botstein D. BIM1 encodes a microtubule-binding protein in yeast. Mol Biol Cell 1997; 8:2677-91. [PMID: 9398684 PMCID: PMC25736 DOI: 10.1091/mbc.8.12.2677] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/1997] [Accepted: 09/15/1997] [Indexed: 02/05/2023] Open
Abstract
A previously uncharacterized yeast gene (YER016w) that we have named BIM1 (binding to microtubules) was obtained from a two-hybrid screen of a yeast cDNA library using as bait the entire coding sequence of TUB1 (encoding alpha-tubulin). Deletion of BIM1 results in a strong bilateral karyogamy defect, hypersensitivity to benomyl, and aberrant spindle behavior, all phenotypes associated with mutations affecting microtubules in yeast, and inviability at extreme temperatures (i.e., >/=37 degrees C or =14 degrees C). Overexpression of BIM1 in wild-type cells is lethal. A fusion of Bim1p with green fluorescent protein that complements the bim1Delta phenotypes allows visualization in vivo of both intranuclear spindles and extranuclear microtubules in otherwise wild-type cells. A bim1 deletion displays synthetic lethality with deletion alleles of bik1, num1, and bub3 as well as a limited subset of tub1 conditional-lethal alleles. A systematic study of 51 tub1 alleles suggests a correlation between specific failure to interact with Bim1p in the two-hybrid assay and synthetic lethality with the bim1Delta allele. The sequence of BIM1 shows substantial similarity to sequences from organisms across the evolutionary spectrum. One of the human homologues, EB1, has been reported previously as binding APC, itself a microtubule-binding protein and the product of a gene implicated in the etiology of human colon cancer.
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Affiliation(s)
- K Schwartz
- Department of Genetics, Stanford University School of Medicine, Stanford, California 94305, USA
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17
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Lai MH, Silverman SJ, Gaughran JP, Kirsch DR. Multiple copies of PBS2, MHP1 or LRE1 produce glucanase resistance and other cell wall effects in Saccharomyces cerevisiae. Yeast 1997; 13:199-213. [PMID: 9090049 DOI: 10.1002/(sici)1097-0061(19970315)13:3<199::aid-yea76>3.0.co;2-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Five sequences were isolated by selection for multiple copy plasmids that conferred resistance to laminarinase, an enzyme that specifically degrades cell wall beta(1-3) glucan linkages. Strains carrying three of these plasmids showed alterations in cell wall glucan labelling. One of these plasmids carried PBS2, a previously identified, non-essential gene which produces a variety of phenotypes and encodes a mitogen-activated protein kinase kinase analogue (Boguslawski and Polazzi, 1987). Cells carrying PBS2 at multiple copy show a small decrease in cell wall beta(1-6) glucans. Measurements of beta(1-3) glucan synthase activity in multi-copy PBS2 cells showed an approximate 30-45% increase in enzyme specific activity while a pbs2 delta disruption strain showed a decrease in glucan synthase activity of approximately 45% relative to control. A pbs2 delta disruption strain was laminarinase super-sensitive and supersensitive to K1 killer toxin while a strain carrying PBS2 at multiple copy was resistant to killer toxin. A second plasmid carried a portion of the MHP1 gene which has been reported to encode a microtubule-interacting protein (Irminger-Finger et al., 1996). The MHP1 gene product is a predicted 1398 amino acid protein and only approximately 80% of the amino portion of this protein is required for laminarinase resistance. Cells carrying the amino portion of MHP1 at multiple copy show a decrease in high molecular weight cell wall beta(1-6) glucans and were killer toxin resistant while a disruption strain was viable and killer toxin super-sensitive. Cells carrying this plasmid showed decreased levels of high molecular weight beta(1-6) glucans and increased glucan synthase activity. The laminarinase resistance conferred by the third plasmid mapped to the previously uncharacterized YCL051W open reading frame and this gene was therefore named LRE1 (laminarinase resistance). The LRE1 gene encodes a non-essential 604 amino acid hydrophilic protein. Unexpectedly, cells carrying LRE1 at multiple copy show no alteration in cell wall glucans or glucan synthase activity. Subcloning experiments demonstrated that the production of these cell wall effects requires the presence of both LRE1 and YCL052C (PBN1), a second open reading frame present on the original plasmid. Cells carrying multiple copies of PBN1 alone show no significant alterations in cell wall glucans or glucan synthase activity, indicating that these effects require the presence of multiple copies of both genes.
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Affiliation(s)
- M H Lai
- American Cyanamid, Agricultural Products Research Division, Princeton, NJ 08543-0400, USA
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