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Yusuf IO, Chen HM, Cheng PH, Chang CY, Tsai SJ, Chuang JI, Wu CC, Huang BM, Sun HS, Chen CM, Yang SH. FGF9 induces neurite outgrowth upon ERK signaling in knock-in striatal Huntington's disease cells. Life Sci 2020; 267:118952. [PMID: 33383048 DOI: 10.1016/j.lfs.2020.118952] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/07/2020] [Accepted: 12/16/2020] [Indexed: 12/17/2022]
Abstract
AIMS Huntington's disease (HD) is a neurodegenerative disease that causes deficits in neurite outgrowth, which suggests that enhancement of neurite outgrowth is a potential direction by which to improve HD. Our previous publications showed that fibroblast growth factor 9 (FGF9) provides anti-apoptosis and anti-oxidative functions in striatal cell models of HD through the extracellular signal-regulated kinases (ERK) pathway, and FGF9 also stimulates cytoskeletons to enhance neurite outgrowth via nuclear factor kappa B (NF-kB) signaling. In this study, we further demonstrate the importance of the ERK pathway for the neurite outgrowth induced by FGF9 in HD striatal models. MATERIALS AND METHODS FGF9 was treated with ERK (U0126) or NF-kB (BAY11-7082) inhibitors in STHdhQ7/Q7 and STHdhQ111/Q111 striatal knock-in cell lines to examine neurite outgrowth, cytoskeletal markers, and synaptic proteins via immunofluorescence staining and Western blotting. NF-kB activity was analyzed by NF-kB promoter reporter assay. KEY FINDINGS Here, we show that suppression of ERK signaling significantly inhibits FGF9-induced neurite outgrowth, cytoskeletal markers, and synaptic proteins in HD striatal cells. In addition, we also show suppression of ERK signaling significantly decreases FGF9-induced NF-kB activation, whereas suppression of NF-kB does not decrease FGF9-induced ERK signaling. These results suggest that FGF9 activates ERK signaling first, stimulates NF-kB upregulation, and then enhances neurite outgrowth in HD striatal cells. SIGNIFICANCE We elucidate the more detailed mechanisms of neurite outgrowth enhanced by FGF9 in these HD striatal cells. This study may provide insights into targeting neurite outgrowth for HD therapy.
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Affiliation(s)
- Issa Olakunle Yusuf
- Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Cheng Kung University and Academia Sinica, Taipei 11529, Taiwan; Institute of Clinical Medicine, College of Medicine, Taiwan; Department of Physiology, College of Medicine, Taiwan
| | - Hsiu-Mei Chen
- Department of Physiology, College of Medicine, Taiwan
| | | | - Chih-Yi Chang
- Department of Physiology, College of Medicine, Taiwan
| | - Shaw-Jenq Tsai
- Department of Physiology, College of Medicine, Taiwan; Institute of Basic Medical Sciences, Taiwan
| | - Jih-Ing Chuang
- Department of Physiology, College of Medicine, Taiwan; Institute of Basic Medical Sciences, Taiwan
| | - Chia-Ching Wu
- Institute of Basic Medical Sciences, Taiwan; Department of Cell Biology and Anatomy, Taiwan
| | - Bu-Miin Huang
- Institute of Basic Medical Sciences, Taiwan; Department of Cell Biology and Anatomy, Taiwan
| | - H Sunny Sun
- Institute of Basic Medical Sciences, Taiwan; Institute of Molecular Medicine, National Cheng Kung University, Tainan 70101, Taiwan
| | - Chuan-Mu Chen
- Department of Life Sciences, College of Life Sciences, National Chung Hsing University, Taichung 40227, Taiwan
| | - Shang-Hsun Yang
- Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Cheng Kung University and Academia Sinica, Taipei 11529, Taiwan; Department of Physiology, College of Medicine, Taiwan; Institute of Basic Medical Sciences, Taiwan.
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Blumenthal J, Cohen-Matsliah SI, Levenberg S. Olfactory Bulb-Derived Cells Seeded on 3D Scaffolds Exhibit Neurotrophic Factor Expression and Pro-Angiogenic Properties. Tissue Eng Part A 2013; 19:2284-91. [DOI: 10.1089/ten.tea.2012.0090] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Affiliation(s)
- Jacob Blumenthal
- Department of Biomedical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | | | - Shulamit Levenberg
- Department of Biomedical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
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Tsymbalyuk VI, Vasil’eva IG, Oleksenko NP, Chopik NG, Tsyubko OI, Galanta OS. Stimulation of cholinogenesis in human fetal nerve cell cultures. CYTOL GENET+ 2013. [DOI: 10.3103/s0095452713030109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Fanarraga ML, Avila J, Zabala JC. Expression of unphosphorylated class III β-tubulin isotype in neuroepithelial cells demonstrates neuroblast commitment and differentiation. Eur J Neurosci 2008. [DOI: 10.1046/j.1460-9568.1999.00459.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Laggner U, Pipp I, Budka H, Hainfellner JA, Preusser M. Immunohistochemical detection of class III ?-tubulin in primary brain tumours: variable expression in most tumour types limits utility as a differential diagnostic marker. Histopathology 2007; 50:949-52. [PMID: 17543088 DOI: 10.1111/j.1365-2559.2007.02696.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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7
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Ku HT, Chai J, Kim YJ, White P, Purohit-Ghelani S, Kaestner KH, Bromberg JS. Insulin-expressing colonies developed from murine embryonic stem cell-derived progenitors. Diabetes 2007; 56:921-9. [PMID: 17395739 DOI: 10.2337/db06-0468] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Previous studies describe a unique culture method for the commitment of murine embryonic stem cells to early endocrine pancreata. In this report, early pancreatic-like beta-cell progenitors were enriched and a colony assay devised to allow these progenitors to differentiate into insulin-expressing colonies in vitro. An embryonic stem cell line with enhanced green fluorescent protein (EGFP) inserted into one allele of neurogenin 3 (Ngn3), a marker for pancreatic endocrine progenitors, was differentiated. During the late stage of culture, 20-30% of cells were Ngn3-EGFP(+). Gene expression profiling using the PancChip microarray platform demonstrated that Ngn3-EGFP(+) cells differentially express endocrine-related genes. A novel semisolid culture method was developed to support the formation of individual insulin/C-peptide-expressing colonies from dissociated single cells. Approximately 0.1-0.6% of Ngn3-EGFP(+) cells gave rise to insulin-expressing colonies, a three- to fivefold enrichment of beta-cell-like progenitors, or insulin-expressing colony-forming units (ICFUs), compared with nonsorted cells. All of the single colonies expressed insulin II, while 69% coexpressed insulin I and 44% coexpressed glucagon. Some single colonies expressed insulin I, insulin II, and Pdx-1 (pancreatic duodenal homeobox-1), but not glucagon. In other colonies, glucagon expression overlapped with C-peptide II in double immunostaining analysis, suggesting heterogeneity among the ICFUs and their resulting colonies. Together, these results demonstrate that progenitors that have the potential to give rise to insulin-expressing cells can be derived from murine embryonic stem cells.
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Affiliation(s)
- Hsun Teresa Ku
- Department of Gene and Cell Medicine and Surgery, Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
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8
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Abstract
The Grueneberg ganglion (GG) is a cluster of neurones present in the vestibule of the anterior nasal cavity. Although its function is still elusive, recent studies have shown that cells of the GG transcribe the gene encoding the olfactory marker protein (OMP) and project their axons to glomeruli of the olfactory bulb, suggesting that they may have a chemosensory function. Chemosensory responsiveness of olfactory neurones in the main olfactory epithelium (MOE) and the vomeronasal organ (VNO) is based on the expression of either odorant receptors or vomeronasal putative pheromone receptors. To scrutinize its presumptive olfactory nature, the GG was assessed for receptor expression by extensive RT-PCR analyses, leading to the identification of a distinct vomeronasal receptor which was expressed in the majority of OMP-positive GG neurones. Along with this receptor, these cells expressed the G proteins Go and Gi, both of which are also present in sensory neurones of the vomeronasal organ. Odorant receptors were expressed by very few cells during prenatal and perinatal stages; a similar number of cells expressed adenylyl cyclase type III and G(olf/s), characteristic signalling elements of the main olfactory system. The findings of the study support the notion that the GG is in fact a subunit of the complex olfactory system, comprising cells with either a VNO-like or a MOE-like phenotype. Moreover, expression of a vomeronasal receptor indicates that the GG might serve to detect pheromones.
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Affiliation(s)
- Jörg Fleischer
- University of Hohenheim, Institute of Physiology, Stuttgart, Germany.
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Fleischer J, Hass N, Schwarzenbacher K, Besser S, Breer H. A novel population of neuronal cells expressing the olfactory marker protein (OMP) in the anterior/dorsal region of the nasal cavity. Histochem Cell Biol 2005; 125:337-49. [PMID: 16273384 DOI: 10.1007/s00418-005-0077-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2005] [Indexed: 10/25/2022]
Abstract
The olfactory marker protein (OMP) is expressed in mature chemosensory neurons in the nasal neuroepithelium. Here, we report the identification of a novel population of OMP-expressing neurons located bilaterally in the anterior/dorsal region of each nasal cavity at the septum. These cells are clearly separated from the regio olfactoria, harboring the olfactory sensory neurons. During mouse development, the arrangement of the anterior OMP-cells undergoes considerable change. They appear at about stage E13 and are localized in the nasal epithelium during early stages; by epithelial budding, ganglion-shaped clusters are formed in the mesenchyme during the perinatal phase, and a filiform layer directly underneath the nasal epithelium is established in adults. The anterior OMP-cells extend long axonal processes which form bundles and project towards the brain. The data suggest that the newly discovered group of OMP-cells in the anterior region of the nasal cavity may serve a distinct sensory function.
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Affiliation(s)
- Jörg Fleischer
- Institute of Physiology, University of Hohenheim, Garbenstrasse 30, 70599, Stuttgart, Germany
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10
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Abstract
Vertebrate tubulin is encoded by a multigene family that produces distinct gene products, or isotypes, of both the alpha- and beta-tubulin subunits. The isotype sequences are conserved across species supporting the hypothesis that different isotypes subserve different functions. To date, however, most studies have demonstrated that tubulin isotypes are freely interchangeable and coassemble into all classes of microtubules. We now report that, in contrast to other isotypes, overexpression of a mouse class V beta-tubulin cDNA in mammalian cells produces a strong, dose-dependent disruption of microtubule organization, increased microtubule fragmentation, and a concomitant reduction in cellular microtubule polymer levels. These changes also disrupt mitotic spindle assembly and block cell proliferation. Consistent with diminished microtubule assembly, there is an increased tolerance for the microtubule stabilizing drug, paclitaxel, which is able to reverse many of the effects of class V beta-tubulin overexpression. Moreover, transfected cells selected in paclitaxel exhibit increased expression of class V beta-tubulin, indicating that this isotype is responsible for the drug resistance. The results show that class V beta-tubulin is functionally distinct from other tubulin isotypes and imparts unique properties on the microtubules into which it incorporates.
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Affiliation(s)
- Rajat Bhattacharya
- Department of Integrative Biology and Pharmacology, The University of Texas Medical School, Houston, Texas 77030, USA
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11
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Katsetos CD, Legido A, Perentes E, Mörk SJ. Class III beta-tubulin isotype: a key cytoskeletal protein at the crossroads of developmental neurobiology and tumor neuropathology. J Child Neurol 2003; 18:851-66; discussion 867. [PMID: 14736079 DOI: 10.1177/088307380301801205] [Citation(s) in RCA: 190] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The expression of the cytoskeletal protein class III beta-tubulin isotype is reviewed in the context of human central nervous system development and neoplasia. Compared to systemic organs and tissues, class III beta-tubulin is abundant in the brain, where it is prominently expressed during fetal and postnatal development. As exemplified in cerebellar neurogenesis, the distribution of class III beta-tubulin is neuron associated, exhibiting different temporospatial gradients in the neuronal progeny of the external granule layer versus the neuroepithelial germinal matrix of the velum medullare. However, transient expression of this protein is also present in the telencephalic subventricular zones comprising putative neuronal and/or glial precursor cells. This temporospatially restricted, potentially non-neuronal expression of class III beta-tubulin may have implications in the accurate identification of presumptive neurons derived from transplanted embryonic stem cells. In the adult central nervous system, the distribution of class III beta-tubulin is almost exclusively neuron specific. Altered patterns of expression are noted in brain tumors. In "embryonal"-type neuronal/neuroblastic tumors of the central nervous system, such as the medulloblastomas, class III beta-tubulin expression is associated with neuronal differentiation and decreased cell proliferation. In contrast, the expression of class III beta-tubulin in gliomas is associated with an ascending grade of histologic malignancy and with correspondingly high proliferative indices. Thus, class III beta-tubulin expression in neuronal or neuroblastic tumors is differentiation dependent, whereas in glial tumors, it is aberrant and/or represents "dedifferentiation" associated with the acquisition of glial progenitor-like phenotype(s). From a diagnostic perspective, the detection of class III beta-tubulin immunostaining in neoplastic cells should not be construed as categorical evidence of divergent neuronal differentiation in tumors, which are otherwise phenotypically glial. Because class III beta-tubulin is present in neoplastic but not in normal differentiated glial cells, the elucidation of molecular mechanisms responsible for the altered expression of this isotype may provide critical insights into the dynamics of the microtubule cytoskeleton in the growth and progression of gliomas.
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Affiliation(s)
- Christos D Katsetos
- Department of Pediatrics, Drexel University College of Medicine, Philadelphia, PA, USA.
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12
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Hari M, Yang H, Zeng C, Canizales M, Cabral F. Expression of class III beta-tubulin reduces microtubule assembly and confers resistance to paclitaxel. Cell Motil Cytoskeleton 2003; 56:45-56. [PMID: 12905530 DOI: 10.1002/cm.10132] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Human brain and testis specific betaIII-tubulin was amplified from a cDNA library, modified to encode a C-terminal hemagglutinin antigen epitope tag, and cloned into a vector that allows tetracycline regulated expression in mammalian cells. Immunofluorescence analysis of transfected Chinese hamster ovary cells demonstrated that expressed HA-tagged betaIII-tubulin is able to assemble with endogenous tubulin into microtubules even though betaIII-tubulin is not a normal constituent of these cells. A stable G418-resistant clone with moderate HAbetaIII-tubulin expression displayed weak (1.5-2-fold) resistance to paclitaxel. A second clone with higher HAbetaIII-tubulin expression could not grow unless tetracycline was present to repress transcription of the transfected cDNA. Analysis of cellular microtubules in each of these clones indicated that incorporation of HAbetaIII-tubulin led to a significant expression-dependent decrease in assembled tubulin. Paclitaxel resistant cells were also directly selected from the transfected cell population using a paclitaxel concentration 4 times higher than the minimum toxic dose. Few cells were able to survive the selection and they grew very slowly. Western blot analysis of these resistant cells revealed very high HAbetaIII-tubulin expression that led to almost complete replacement of endogenous beta-tubulin at steady state. Transfected betaIII-tubulin with no epitope tag behaved in a very similar fashion indicating that presence of the HA tag had no discernible functional effect. The results demonstrate that betaIII-tubulin diminishes microtubule assembly, is toxic when present at high levels, but is able to confer weak resistance to paclitaxel when expressed at moderate levels in mammalian cells.
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Affiliation(s)
- Malathi Hari
- Department of Integrative Biology and Pharmacology, University of Texas Medical School, Houston, TX 77225, USA
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Abstract
The differential cellular expression of class III beta-tubulin isotype (betaIII) is reviewed in the context of human embryological development and neoplasia. As compared to somatic organs and tissues, betaIII is abundant in the central and peripheral nervous systems (CNS and PNS) where it is prominently expressed during fetal and postnatal development. As exemplified in cerebellar and sympathoadrenal neurogenesis, the distribution of betaIII is neuron-associated, exhibiting distinct temporospatial gradients according to the regional neuroepithelia of origin. However, transient expression of this protein is also present in the subventricular zones of the CNS comprising putative neuronal- and/or glial precursor cells, as well as in Kulchitsky neuroendocrine cells of the fetal respiratory epithelium. This temporally restricted, potentially non-neuronal expression may have implications in the identification of presumptive neurons derived from embryonic stem cells. In adult tissues, the distribution of betaIII is almost exclusively neuron-specific. Altered patterns of expression are noted in cancer. In "embryonal"- and "adult-type" neuronal tumors of the CNS and PNS, betaIII is associated with neuronal differentiation and decreased cell proliferation. In contrast, the presence of betaIII in gliomas and lung cancer is associated with an ascending histological grade of malignancy. Thus, betaIII expression in neuronal tumors is differentiation-dependent, while in non-neuronal tumors it is aberrant and/or represents "dedifferentiation" associated with the acquisition of progenitor-like phenotypic properties. Increased expression in various epithelial cancer cell lines is associated with chemoresistance to taxanes. Because betaIII is present in subpopulations of neoplastic, but not in normal differentiated glial or somatic epithelial cells, the elucidation of mechanisms responsible for the altered expression of this isotype may provide insights into the role of the microtubule cytoskeleton in tumorigenesis and tumor progression.
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Affiliation(s)
- Christos D Katsetos
- Department of Pediatrics, Section of Neurology, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA.
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Carpenter MK, Cui X, Hu ZY, Jackson J, Sherman S, Seiger A, Wahlberg LU. In vitro expansion of a multipotent population of human neural progenitor cells. Exp Neurol 1999; 158:265-78. [PMID: 10415135 DOI: 10.1006/exnr.1999.7098] [Citation(s) in RCA: 366] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The isolation and expansion of human neural progenitor cells have important potential clinical applications, because these cells may be used as graft material in cell therapies to regenerate tissue and/or function in patients with central nervous system (CNS) disorders. This paper describes a continuously dividing multipotent population of progenitor cells in the human embryonic forebrain that can be propagated in vitro. These cells can be maintained and expanded using a serum-free defined medium containing basic fibroblast growth factor (bFGF), leukemia inhibitory factor (LIF), and epidermal growth factor (EGF). Using these three factors, the cell cultures expand and remain multipotent for at least 1 year in vitro. This period of expansion results in a 10(7)-fold increase of this heterogeneous population of cells. Upon differentiation, they form neurons, astrocytes, and oligodendrocytes, the three main phenotypes in the CNS. Moreover, GABA-immunoreactive and tyrosine hydroxylase-immunoreactive neurons can be identified. These results demonstrate the feasibility of long-term in vitro expansion of human neural progenitor cells. The advantages of such a population of neural precursors for allogeneic transplantation include the ability to provide an expandable, well-characterized, defined cell source which can form specific neuronal or glial subtypes.
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Affiliation(s)
- M K Carpenter
- Cell and Molecular Neurobiology, CytoTherapeutics, Inc., Lincoln, Rhode Island, 02865, USA.
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Katsetos CD, Herman MM, Balin BJ, Vinores SA, Hessler RB, Arking EJ, Karkavelas G, Frankfurter A. Class III beta-tubulin isotype (beta III) in the adrenal medulla: III. Differential expression of neuronal and glial antigens identifies two distinct populations of neuronal and glial-like (sustentacular) cells in the PC12 rat pheochromocytoma cell line maintained in a Gelfoam matrix system. Anat Rec (Hoboken) 1998; 250:351-65. [PMID: 9517852 DOI: 10.1002/(sici)1097-0185(199803)250:3<351::aid-ar10>3.0.co;2-n] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND The rat PC12 pheochromocytoma cell line provides an established system for the study of neuronal differentiation. To our knowledge, glial differentiation has not been reported in this cell line. METHODS We have studied, by immunohistochemistry and immunoblotting, the presence of neuronal cytoskeletal antigens [class III beta-tubulin isotype (beta III), microtubule associated proteins MAP2, MAP1B and tau, and different neurofilament (NF) protein components], and synaptophysin in comparison with the glial fibrillary acidic protein (GFAP) and S-100 protein in the PC12 cell line. In three different experiments, PC12 cells were maintained in a three-dimensional gelatin foam (Gelfoam) matrix system for up to 34 days with and without treatment with 1 mM dibutyryl cyclic (dc)AMP. Immunohistochemistry was performed on explants ranging from 2 to 32 days-in vitro, which were fixed in either Bouin's solution, 70% ethanol, or 10% neutral-buffered formalin and embedded in paraffin. Immunoblotting was performed on Gelfoam explants with a panel of antibodies against all aforementioned neuronal and glial markers. Additional immunoblot experiments using anti-GFAP and anti-beta III monoclonal antibodies in cell suspensions and homogenates from PC12 monolayer cultures were carried out to compare growth conditions in relation to the expression of these proteins. RESULTS Beta III and MAP2 were demonstrated by immunohistochemistry and immunoblotting of PC12 explants maintained for up to 32 days in Gelfoam matrices with and without treatment with dcAMP. Intense filamentous and granular beta III staining of PC12 cells was observed in dcAMP-treated cultures concomitant with neuronal morphologic alterations (neuritogenesis and ganglionic phenotype). In untreated cultures, beta III staining was present in less differentiated cells, as well in cells undergoing neuritic development. The neuronal phenotype of PC12 cells was confirmed by staining for MAP2, tau, and NF proteins, as well as for synaptophysin. The presence of beta III, MAP2, MAP1B, tau, and NF proteins was confirmed by immunoblotting. Clusters of GFAP-positive and S-100 protein-positive spindle cells, phenotypically distinct from the chromaffin-like or neuronal cells, were demonstrated in Gelfoam explants at 5-30 days in vitro. In 30-day-old cultures treated with dcAMP, there was strong filamentous GFAP and diffuse S-100 protein staining in an increased number of sustentacular-like PC12 cells. GFAP staining was corroborated by immunoblotting of explants maintained under identical conditions in vitro. In contrast, immunoblots performed on homogenates from PC12 suspension and monolayer cultures were GFAP-negative. CONCLUSIONS Neuronal and glial-like, presumed sustentacular, phenotypes were demonstrated in PC12 cells grown in Gelfoam matrices with and without treatment with dcAMP for up to 34 days. To our knowledge, the occurrence of glial differentiation in the PC12 line is a hitherto unreported finding. Adult rat medullary sustentacular cells are known to express S-100 and GFA proteins (Suzuki and Kachi, Kaibogaku Zasshi-Anat 70(2): 130-139, 1995), and the organ culture system employed in our study may well have favored this direction of differentiation.
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Affiliation(s)
- C D Katsetos
- Neuropathology Laboratory, Hahnemann University, Philadelphia, Pennsylvania, USA
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Karkavelas G, Katsetos CD, Geddes JF, Herman MM, Vinores SA, Cooper HS, Provencio J, Frankfurter A. Class III beta-tubulin isotype (beta III) in the adrenal medulla: II. Localization in primary human pheochromocytomas. Anat Rec (Hoboken) 1998; 250:344-50. [PMID: 9517851 DOI: 10.1002/(sici)1097-0185(199803)250:3<344::aid-ar9>3.0.co;2-#] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND The Class III beta-tubulin isotype (beta III) is expressed specifically in central and peripheral nervous system neurons at various stages of neuronal differentiation. We have shown previously that beta III is expressed in a differentiation-dependent manner in human neuroblastomas arising in the adrenal medulla and sympathetic chains (Katsetos et al., Clin Neuropathol 13:241-255, 1994). The neuronal distribution of beta III in the developing and mature human adrenal medullae is detailed in the companion article (Katsetos et al., 1998A). METHODS We have compared the localization of the neuronal beta III to S-100 protein, a sustentacular cell marker, in 14 formalin-fixed, paraffin-embedded primary human pheochromocytomas of the adrenal medulla and 14 adrenocortical tumors (adenomas and carcinomas). RESULTS In pheochromocytomas, beta III staining was present in all tumors, but the number of stained cells varied in the two neural neoplastic phenotypes. Although the majority of chromaffin-like cells were beta III-positive, there was a lack of beta III in one-third of the tumor cells. Compared to chromaffin-like phenotypes, neuronal (ganglion-like cells) were invariably beta III-positive. Stromal sustentacular cells, stromal fibroblasts, and tumor blood vessels were beta III-negative. Sustentacular cells in pheochromocytomas were S-100 protein-positive, but beta III-negative. Primary adrenocortical tumors were beta III-negative with the exception of rare beta III-positive cells demonstrated in one case. CONCLUSIONS The distribution of beta III in human pheochromocytomas of the adrenal gland is differentiation-dependent, closely recapitulating chromaffin cell and neuronal phenotypes of the normal adrenal medulla. Our findings indicate that beta III may be used as one of the adjuvant neural markers in the differential diagnosis of adrenal tumors, i.e., pheochromocytoma versus adrenocortical carcinoma. The occurrence of rare beta III-positive cells in cortical carcinomas is exceptional and probably represents the acquisition of a divergent neuroendocrine phenotype. The significance of the latter is unclear, although it may constitute a marker for malignancy.
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Affiliation(s)
- G Karkavelas
- Neuropathology Laboratory, Hahnemann University, Philadelphia, Pennsylvania, USA
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Abstract
The olfactory neuroepithelium retains the unique capacity to produce a new set of mature neurons every three to four weeks from a precursor population situated at the base of the epithelium. It is not known however, whether developing olfactory neurons in the adult rat follow the same program that is initiated embryonically. By tracking the expression of beta-III tubulin (by immunoreactivity to TuJ-1, an isoform-specific antibody) throughout embryogenesis, we have demonstrated a commitment to the olfactory neuron lineage in a subset of cells in the embryonic olfactory placode and followed their development into adulthood. We have also shown that this developmental pattern of beta-III tubulin expression is recapitulated in neurons undergoing a synchronized neurogenic response to either physical or chemical lesion in the adult neuroepithelium. The embryonic expression pattern reported here is similar to, but earlier than that reported for other markers of developing neurons, such as growth-associated protein-43 and neural cell adhesion molecule. The results of these studies suggest the retention of a conserved neurogenic program from embryonic to adult life in the olfactory neuron and, in addition, support the use of a readily accessible system such as the regenerating olfactory neuroepithelium as an alternative means of studying genes which may be crucial to normal neuronal development.
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Affiliation(s)
- A J Roskams
- Department of Neuroscience, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
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18
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Abstract
Tubulin, the subunit protein of microtubules, is an alpha/beta heterodimer. In many organisms, both alpha and beta exist in numerous isotypic forms encoded by different genes. In addition, both alpha and beta undergo a variety of posttranslational covalent modifications, including acetylation, phosphorylation, detyrosylation, polyglutamylation, and polyglycylation. In this review the distribution and possible functional significance of the various forms of tubulin are discussed. In analyzing the differences among tubulin isotypes encoded by different genes, some appear to have no functional significance, some increase the overall adaptability of the organism to environmental challenges, and some appear to perform specific functions including formation of particular organelles and interactions with specific proteins. Purified isotypes also display different properties in vitro. Although the significance of all the covalent modification of tubulin is not fully understood, some of them may influence the stability of modified microtubules in vivo as well as interactions with certain proteins and may help to determine the functional role of microtubules in the cell. The review also discusses isotypes of gamma-tubulin and puts various forms of tubulin in an evolutionary context.
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Affiliation(s)
- R F Ludueña
- Department of Biochemistry, University of Texas Health Science Center at San Antonio 78284, USA
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Abstract
Nerve growth factor (NGF) produces both rapid and delayed cellular responses that are involved in neuronal differentiation. Neurite formation, a conspicuous delayed response, is accompanied by phosphorylation of beta-tubulin in PC12 cells. The present work provides further characterization of the phospho form of beta-tubulin in this neuronal model system with regard to isotype, cellular localization, and the circumstances that favor its formation. The results indicate that neuron-specific type III beta-tubulin (beta III-tubulin) is selectively affected during neurite formation. This phosphorylation occurs relatively late in the NGF signal transduction cascade and increases progressively with increasing duration of NGF treatment concomitant with more extensive neurite growth. The subcellular distribution of beta III-tubulin is not markedly different from that of total tubulin, but the phosphorylated protein is uniquely associated with microtubules that are calcium and cold labile. Although NGF is capable of inducing phosphorylation of beta III-tubulin, it is not necessarily sufficient. Based on experiments that employ either nonpermissive substrate conditions or microtubule-depolymerizing drugs, this phosphorylation requires neurite outgrowth. Direct measurements of the phospho form in neurites versus cell bodies by means of a microculture system indicate that phosphorylated beta III-tubulin is enriched in neurites. The enrichment of phospho-beta III-tubulin in calcium- and cold-labile polymer within neurites and its near absence in nonneurite bearing, NGF-treated cells suggests a role for this posttranslationally modified protein in the regulation of dynamic microtubules involved in neurite formation.
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Affiliation(s)
- J M Aletta
- Department of Pharmacology and Toxicology, University at Buffalo, School of Medicine, New York 14214-3000, USA.
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20
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Abstract
The hyt/hyt mouse has an autosomal recessive, fetal onset, characterized by severe hypothyroidism that persists throughout life and is a reliable model of human sporadic congenital hypothyroidism. The hypothyroidism in the hyt/hyt mouse reflects the hyporesponsiveness of the thyroid gland to thyrotropin (TSH). This is attributable to a point mutation of C to T at nucleotide position 1666, resulting in the replacement of a Pro with Leu at position 556 in transmembrane domain IV of the G protein-linked TSH receptor. This mutation leads to a reduction in all cAMP-regulated events, including thyroid hormone synthesis. The diminution in T3/T4 in serum and other organs, including the brain, also leads to alterations in the level and timing of expression of critical brain molecules, i.e. selected tubulin isoforms (M beta 5, M beta 2, and M alpha 1), microtubule associated proteins (MAPs), and myelin basic protein, as well as to changes in important neuronal cytoskeletal events, i.e. microtubule assembly and SCa and SCb axonal transport. In the hyt/hyt mouse, fetal hypothyroidism leads to reductions in M beta 5, M beta 2, and M alpha 1 mRNAs, important tubulin isoforms, and M beta 5 and M beta 2 proteins, which comprise the microtubules. These molecules are localized to layer V pyramidal neurons in the sensorimotor cortex, a site of differentiating neurons, as well as a site for localization of specific thyroid hormone receptors. These molecular abnormalities in specific cells and at specific times of development or maturation may contribute to the observed neuroanatomical abnormalities, i.e. altered neuronal process growth and maintenance, synaptogenesis, and myelination, in hypothyroid brain. Abnormal neuroanatomical development in selected brain regions may be the factor underlying the abnormalities in reflexive, locomotor, and adaptive behavior seen in the hyt/hyt mouse and other hypothyroid animals.
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Affiliation(s)
- E Biesiada
- Division of Neurology, Children's Hospital of Orange County, CA 92868, USA
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21
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Laferrière NB, Brown DL. Expression and posttranslational modification of class III beta-tubulin during neuronal differentiation of P19 embryonal carcinoma cells. Cell Motil Cytoskeleton 1996; 35:188-99. [PMID: 8913640 DOI: 10.1002/(sici)1097-0169(1996)35:3<188::aid-cm2>3.0.co;2-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We have used a combination of immunofluorescence microscopy, northern blotting, ELISA, and isoelectric focusing to characterize the expression of neuronal Class III beta-tubulin in P19 embryonal carcinoma cells induced to differentiate along a neuronal pathway by retinoic acid. Following 48 h differentiation, beta-III tubulin mRNA is evident and beta-III tubulin appears in the mitotic spindle of neuroblasts. Neurite outgrowth is obvious by day 3, and beta-III tubulin protein and mRNA levels increase concurrently until approximately day 7, when beta-III mRNA levels begin to decrease while protein levels remain high. In addition, increasingly acidic beta-III tubulin isoforms appear during neuronal differentiation. The expression of these isoelectric variants occurs concomitant with a temporal increase in the levels of beta-III tubulin present in the colchicine-stable microtubules. These results implicate posttranslational modifications of beta-III tubulin in the increased microtubule stability noted in differentiating P19 neurons.
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Affiliation(s)
- N B Laferrière
- Department of Biology, University of Ottawa, Ontario, Canada
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22
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Haber M, Burkhart CA, Regl DL, Madafiglio J, Norris MD, Horwitz SB. Altered expression of M beta 2, the class II beta-tubulin isotype, in a murine J774.2 cell line with a high level of taxol resistance. J Biol Chem 1995; 270:31269-75. [PMID: 8537394 DOI: 10.1074/jbc.270.52.31269] [Citation(s) in RCA: 113] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
A series of taxol- and taxotere-resistant J774.2 cell lines has been characterized with respect to altered expression of beta-tubulin, the cellular target for these drugs. Vertebrates have six classes of beta-tubulin isotypes, each displaying a distinct pattern of expression. Although the functional significance of multiple beta-tubulins has not been fully defined, there is evidence that the individual isotypes contribute to differences in microtubule dynamics and drug binding. To determine if alterations in the expression of beta-tubulin isotypes play a role in taxol resistance, a PCR-based methodology was developed that permits highly specific amplification of each of the six known murine beta-tubulin isotypes. Two isotypes, M beta 5 and M beta 3, were expressed abundantly in the drug-sensitive parental J774.2 cells. Although expressed at an extremely low level in the parental cells, expression of the M beta 2 isotype was increased 21-fold (< 0.005) in the cell line most resistant to taxol. These findings suggest that a cell can alter its relative tubulin isotype composition in response to an external stress and specifically imply that altered expression of M beta 2, the class II beta-tubulin isotype, may contribute to the development of high resistance to taxol.
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Affiliation(s)
- M Haber
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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23
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Affiliation(s)
- R F Ludueña
- Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284-7760
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24
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Affiliation(s)
- J M Andreu
- Centro de Investigaciones Biológicas, C.S.I.C., Madrid, Spain
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25
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Abstract
Four different isotypes of beta-tubulin are known to be expressed in mammalian brain. Monoclonal antibodies against beta II, beta III, and beta IV were used to characterize the beta-tubulin isotypes in two ciliated bovine tissues: non-motile sensory cilia of retinal rod cells and motile cilia of tracheal epithelium. Retinal rod outer segment (ROS) connecting cilia and cytoskeletons were purified by density gradient centrifugation. This preparation contained more than 20 major protein components, as shown by dodecyl sulfate polyacrylamide gel electrophoresis. Electroblots were used to quantitate the relative amounts of beta II, beta III, and beta IV. The connecting cilium and cytoskeleton of the rod outer segment has less type III beta-tubulin than brain and more type IV. The ratio of beta IV to beta II in the ROS is nearly a factor of 8 larger than in brain. Electron microscopic immunocytochemistry showed extensive labeling of cilia by anti-type IV in thin sections of retinas and trachea, and also in purified ROS cilia and cytoskeletons. Labeling of cilia by anti-beta II was also observed, although in the purified ROS cilia and cytoskeleton, the anti-beta II labeling was primarily on amorphous non-ciliary material. The results suggest that both motile and non-motile cilia are enriched in the type IV beta-tubulin subunit.
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Affiliation(s)
- R Renthal
- Department of Biochemistry, University of Texas Health Science Center, San Antonio 78249
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26
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Linhartová I, Dráber P, Dráberová E, Viklický V. Immunological discrimination of beta-tubulin isoforms in developing mouse brain. Post-translational modification of non-class-III beta-tubulins. Biochem J 1992; 288 ( Pt 3):919-24. [PMID: 1281983 PMCID: PMC1131974 DOI: 10.1042/bj2880919] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Individual beta-tubulin isoforms in developing mouse brain were characterized using immunoblotting, after preceding high-resolution isoelectric focusing, with monoclonal antibodies against different structural regions of beta-tubulin. Some of the antibodies reacted with a limited number of tubulin isoforms in all stages of brain development and in HeLa cells. The epitope for the TU-14 antibody was located in the isotype-defining domain and was present on the beta-tubulin isotypes of classes I, II and IV, but absent on the neuron-specific class-III isotype. The data suggest that non-class-III beta-tubulins in mouse brain are substrates for developmentally regulated post-translational modifications and that beta-tubulins of non-neuronal cells are also post-translationally modified.
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Affiliation(s)
- I Linhartová
- Institute of Molecular Genetics, Czechoslovak Academy of Sciences, Prague
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27
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Abstract
The expression of the class III beta-tubulin isotype was studied in cultured brain neurons by means of a monoclonal antibody (TuJ1). The results obtained indicate that during early axonal outgrowth most of the class III beta-tubulin is not incorporated into microtubules, a phenomenon which is also observed under conditions which alter the rate and extent of the neurite outgrowth response. On the other hand, a dramatic increase in its incorporation into microtubules is observed after the neurons have differentiated their neurites as axons and dendrites. In addition, the appearance of colchicine-resistant microtubules containing this isotype, a phenomenon which occurs late in neurite development, is highly coincident with the appearance of stable microtubules containing high molecular weight microtubule-associated proteins (MAPs). This pattern is different from that of the accumulation and incorporation of other beta-tubulin isotypes into microtubules. Taken collectively, our results indicate that differences exist in the in vivo utilization of tubulin isotypes in developing brain neurons and suggest that the class III beta-tubulin isotype is not a primary factor involved in the regulation of microtubule assembly during early neurite outgrowth, but that it may be important for maintaining further neurite elongation and/or determining some unique binding property of MAPs to specific microtubule subsets.
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Affiliation(s)
- A Ferreira
- Department of Biology, University of Virginia, Charlottesville
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28
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Falconer MM, Echeverri CJ, Brown DL. Differential sorting of beta tubulin isotypes into colchicine-stable microtubules during neuronal and muscle differentiation of embryonal carcinoma cells. Cell Motil Cytoskeleton 1992; 21:313-25. [PMID: 1628327 DOI: 10.1002/cm.970210407] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Pluripotent P19 embryonal carcinoma (EC) cells were differentiated along the neuronal and muscle pathways. Comparisons of class I, II, III, and IV beta tubulin isotypes in total and colchicine-stable microtubule (MT) arrays from uncommitted EC, neuronal, and muscle cells were made by immunoblotting and by indirect immunofluorescence microscopy. In undifferentiated EC cells the relative amounts of these four isotypes are the same in both the total and stable MT populations. Subcellular sorting of beta tubulin isotypes was demonstrated in both neuronal and muscle differentiated cells. During neuronal differentiation, class II beta tubulin is preferentially incorporated into the colchicine-stable MTs while class III beta tubulin is preferentially found in the colchicine-labile MTs. The subcellular sorting of class II into stable MTs correlates with the increased staining of MAP 1B, and with the expression of MAP 2C and tau. Although muscle differentiated cells express class II beta tubulin, stable MTs in these cells do not preferentially incorporate this isotype but instead show increased incorporation of class IV beta tubulin. Muscle cells do not show high levels of MAP 1B and do not express MAP 2C or tau. These results are consistent with the hypothesis that a subcellular sorting of tubulin isotypes is the result of a complex interaction between tubulin isotypes and MT-associated proteins.
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Affiliation(s)
- M M Falconer
- Department of Biology, University of Ottawa, Canada
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29
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Abstract
The biological significance of tubulin isotypes lies in their ability to function in different chemical and physical environments. Recent papers document the origin and distribution of several new tubulin isotypes and suggest new ways for studying their assembly and function in specialized cells.
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Affiliation(s)
- D B Murphy
- Department of Cell Biology and Anatomy, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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30
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31
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Matthews KA, Miller DF, Kaufman TC. Functional implications of the unusual spatial distribution of a minor alpha-tubulin isotype in Drosophila: a common thread among chordotonal ligaments, developing muscle, and testis cyst cells. Dev Biol 1990; 137:171-83. [PMID: 2295363 DOI: 10.1016/0012-1606(90)90018-e] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Three of the four alpha-tubulin genes in Drosophila melanogaster are temporally regulated. mRNA from one of these genes, alpha 85E-tubulin, first appears in 6- to 8-hr embryos and persists, with marked fluctuations, through the end of pupal development. In adults, alpha 85E mRNA has been unequivocally identified only in testes. In the present study, isotype-specific antibodies have been used to localize alpha 85E tubulin protein in whole tissues. The results demonstrate a spatially restricted expression pattern of the alpha 85E gene that includes tissues of both ectodermal and mesodermal origins. Specifically, embryonic accumulation of alpha 85E tubulin is limited to support cells of chordotonal organs and the developing musculature of the viscera and body wall. In late third instar larvae, chordotonal organs and a subset of larval nerves, but not muscle, stain with anti-alpha 85E. The timing of protein accumulation during pupal development suggests that alpha 85E tubulin is involved in the construction of the adult as well as the larval musculature. In testis, only the somatically derived cyst cells that surround developing spermatid bundles accumulate alpha 85E-tubulin. The cell types that express alpha 85E share a requirement for extensive cell shape changes during development, suggesting that this minor alpha-tubulin may have distinct functional properties.
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Affiliation(s)
- K A Matthews
- Department of Biology, Indiana University, Bloomington 47405
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32
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Lee MK, Tuttle JB, Rebhun LI, Cleveland DW, Frankfurter A. The expression and posttranslational modification of a neuron-specific beta-tubulin isotype during chick embryogenesis. Cell Motil Cytoskeleton 1990; 17:118-32. [PMID: 2257630 DOI: 10.1002/cm.970170207] [Citation(s) in RCA: 496] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Five beta-tubulin isotypes are expressed differentially during chicken brain development. One of these isotypes is encoded by the gene c beta 4 and has been assigned to an isotypic family designated as Class III (beta III). In the nervous system of higher vertebrates, beta III is synthesized exclusively by neurons. A beta III-specific monoclonal antibody was used to determine when during chick embryogenesis c beta 4 is expressed, the cellular localization of beta III, and the number of charge variants (isoforms) into which beta III can be resolved by isoelectric focusing. On Western blots, beta III is first detectable at stages 12-13. Thereafter, the relative abundance of beta III in brain increases steadily, apparently in conjunction with the rate of neural differentiation. The isotype was not detectable in non-neural tissue extracts from older embryos (days 10-14) and hatchlings. Western blots of protein separated by two-dimensional gel electrophoresis (2D-PAGE) reveal that the number of beta III isoforms increases from one to three during neural development. This evidence indicates that beta III is a substrate for developmentally regulated, multiple-site posttranslational modification. Immunocytochemical studies reveal that while c beta 4 expression is restricted predominantly to the nervous system, it is transiently expressed in some embryonic structures. More importantly, in the nervous system, immunoreactive cells were located primarily in the non-proliferative marginal zone of the neural epithelia. Regions containing primarily mitotic neuroblasts were virtually unstained. This localization pattern indicates that c beta 4 expression occurs either during or immediately following terminal mitosis, and suggests that beta III may have a unique role during early neuronal differentiation and neurite outgrowth.
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Affiliation(s)
- M K Lee
- Neuroscience Program, University of Virginia, Charlottesville
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33
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Abstract
Cells contain multiple tubulin isotypes that are the products of different genes and posttranslational modifications. It has been proposed that tubulin isotypes become segregated into different classes of microtubules each adapted to specific activities and functions. To determine if mixtures of tubulin isotypes segregate into different classes of polymers in vitro, we used immunoelectron microscopy to examine the composition of microtubule copolymers that assembled from mixtures of purified tubulin subunits from chicken brain and erythrocytes, each of which has been shown to exhibit distinct assembly properties in vitro. We observed that (a) the two isotypes coassemble rapidly and efficiently despite the fact that each isotype exhibits its own unique biochemical and assembly properties; (b) at low monomer concentrations the ratio of tubulin isotypes changes along the lengths of elongating copolymers resulting in gradients in immuno-gold labeling; (c) two distinct classes of copolymers each containing a distinct ratio of isotypes assemble simultaneously in the same subunit mixture; and (d) subunits and polymers of different isotypes associate nearly equally well with each other, there being only a slight bias favoring interactions among subunits and polymers of the same isotype. The observations agree with previous studies on the homogeneous distribution of multiple isotypes within cells and suggest that if segregation of isotypes does occur in vivo, it is most likely directed by cell-specific microtubule-associated proteins (MAPs) or specialized intracellular conditions.
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Affiliation(s)
- H N Baker
- Department of Cell Biology and Anatomy, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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34
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Abstract
The determination of the structure and the expression of dynein during embryonic development are central to the understanding of dynein function. As an important first step toward these objectives, cDNAs encoding portions of sea urchin ciliary dynein were identified by antibody screening of a sea urchin cDNA expression library. Because of the complete lack of protein sequence data, it was first necessary to prove the identity of the dynein cDNAs. Of the five cDNA inserts initially cloned, one, designated P72A1, was characterized extensively. Four independent criteria demonstrated that P72A1 encoded a portion of a dynein heavy chain. (1) The beta-galactosidase-P72A1 fusion protein affinity-purified dynein-specific antibodies from crude antiserum. (2) Two other antisera to dynein, raised independently of the antiserum used to screen the cDNA library, reacted with the fusion protein. (3) A new antiserum raised against the fusion protein reacted with authentic dynein heavy chain on Western blots and stained embryonic cilia by indirect immunofluorescence microscopy. (4) Two new antisera, elicited against opposite ends of the P72A1 open reading frame, each reacted with authentic dynein heavy chain protein. Western blot analyses of dissociated dynein heavy chains revealed that P72A1 encoded a portion of the beta heavy chain. Epitope mapping experiments confirmed the identity of P72A1 as part of the beta heavy chain and also demonstrated that P72A1 encoded epitopes of the carboxyl-terminal fragment B domain of the dynein beta heavy chain. Northern blot analyses of poly(A)+ RNA revealed that P72A1 hybridized with a large RNA species ca. 12.5 kb in length. The dynein mRNA concentration increased during embryonic development. Dot blot analyses of RNA isolated at various times after embryo deciliation demonstrated that the dynein beta heavy chain mRNA accumulated rapidly in response to deciliation. The accumulation was similar to but not identical with the induction of tubulin mRNA in response to the same stimulus.
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Affiliation(s)
- K R Foltz
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907
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35
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Driscoll M, Dean E, Reilly E, Bergholz E, Chalfie M. Genetic and molecular analysis of a Caenorhabditis elegans beta-tubulin that conveys benzimidazole sensitivity. J Cell Biol 1989; 109:2993-3003. [PMID: 2592410 PMCID: PMC2115974 DOI: 10.1083/jcb.109.6.2993] [Citation(s) in RCA: 174] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Benzimidazole anti-microtubule drugs, such as benomyl, induce paralysis and slow the growth of the nematode Caenorhabditis elegans. We have identified 28 mutations in C. elegans that confer resistance to benzimidazoles. All resistant mutations map to a single locus, ben-1. Virtually all these mutations are genetically dominant. Molecular cloning and DNA sequence analysis established that ben-1 encodes a beta-tubulin. Some resistant mutants are completely deleted for the ben-1 gene. Since the deletion strains appear to be fully resistant to the drugs, the ben-1 product appears to be the only benzimidazole-sensitive beta-tubulin in C. elegans. Furthermore, since animals lacking ben-1 are viable and coordinated, the ben-1 beta-tubulin appears to be nonessential for growth and movement. The ben-1 function is likely to be redundant in the nematode genome.
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Affiliation(s)
- M Driscoll
- Department of Biological Sciences, Columbia University, New York 10027
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