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Steinboeck F, Kristufek D. Identification of the cytolinker protein plectin in neuronal cells - expression of a rodless isoform in neurons of the rat superior cervical ganglion. Cell Mol Neurobiol 2007; 25:1151-69. [PMID: 16392043 DOI: 10.1007/s10571-005-8503-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2004] [Accepted: 08/12/2004] [Indexed: 10/25/2022]
Abstract
Plectin, a large (> 500 kDa) dumbbell-shaped cytolinker protein plays an important role in the organization of the cytoskeletal network and the maintenance of cell integrity in a wide variety of tissues and cell types. Earlier experiments revealed the presence of plectin in the central nervous system, whereas the expression in the peripheral nervous system remained unclear. Our results obtained with reverse transcriptase-PCR (RT-PCR) provide evidence that plectin is expressed in structures of the rat peripheral nervous system. In addition to well-characterized plectin transcripts we were able to reveal novel splicing variants affecting the region coding for the central rod domain. Previous studies report a high, but tissue-specific variability of the N-terminal domain of plectin due to alternatively spliced first coding exons and the optionally spliced small exons 2 alpha and 3 alpha. We demonstrate for the first time, using single-cell RT-PCR and immunocytochemistry, that plectin is expressed in neurons of the rat superior cervical ganglion (SCG). Plectin transcripts of single SCG neurons, starting with exon 1c as the first coding exon, contain the optionally spliced exon 2 alpha but lack exon 31. These data therefore suggest that plectin is expressed in rat SCG neurons as a rodless isoform with the molecular mass of 390 kDa.
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Affiliation(s)
- Ferdinand Steinboeck
- Institute of Cancer Research, Department of Medicine I, Medical University of Vienna, Vienna, Austria.
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152
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Liu JJ, Ding J, Wu C, Bhagavatula P, Cui B, Chu S, Mobley WC, Yang Y. Retrolinkin, a membrane protein, plays an important role in retrograde axonal transport. Proc Natl Acad Sci U S A 2007; 104:2223-8. [PMID: 17287360 PMCID: PMC1892971 DOI: 10.1073/pnas.0602222104] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Retrograde axonal transport plays an important role in the maintenance of neuronal functions, but the mechanism is poorly defined partly because the constituents of the retrograde transport system and their interactions have yet to be elucidated. Of special interest is how dynein/dynactin motor proteins interact with membrane cargoes. Here, we report that an endosomal vesicle protein, termed retrolinkin, functions as a receptor tethering vesicles to dynein/dynactin through BPAG1n4. Retrolinkin, a membrane protein highly enriched in neuronal endosomes, binds directly to BPAG1n4. Deletion of retrolinkin membrane-association domains disrupts retrograde vesicular transport, recapitulating the BPAG1 null phenotype. We propose that retrolinkin acts with BPAG1n4 to specifically regulate retrograde axonal transport. Our work lays the foundation for understanding fundamental issues of axonal transport and provides insights into the molecular mechanisms underlying human neurodegenerative disorders.
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Affiliation(s)
- Jia-Jia Liu
- *Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305; and
| | - Jianqing Ding
- *Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305; and
| | - Chengbiao Wu
- *Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305; and
| | - Prasanthi Bhagavatula
- *Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305; and
| | - Bianxiao Cui
- Department of Physics, Stanford University, Stanford, CA 94305
| | - Steve Chu
- Department of Physics, Stanford University, Stanford, CA 94305
| | - William C. Mobley
- *Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305; and
| | - Yanmin Yang
- *Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305; and
- To whom correspondence should be addressed. E-mail:
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153
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Di Zenzo G, Marazza G, Borradori L. Bullous pemphigoid: physiopathology, clinical features and management. ADVANCES IN DERMATOLOGY 2007; 23:257-88. [PMID: 18159905 DOI: 10.1016/j.yadr.2007.07.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
There has been a considerable progress in the understanding of the physiopathology of BP during the past 2 decades. The insights into the humoral and cellular immune response against BP180 and BP230 have increased significantly. Nevertheless, the factors underlying the initiation of the disease leading to a disruption of self-tolerance remain unclear. Clinically, the disease shows protean presentations, and diagnostic delay is common. A practical, relevant, and unresolved question is how to identify patients suffering from BP at an early stage of the disease, when direct immunofluorescence microscopy findings still may be negative. The characterization of markers allowing the differentiation of BP from other pruritic eruptions occurring in the elderly population would be extremely helpful in daily practice. Finally, despite the knowledge that potent topical steroids are efficient in controlling the disease, management of BP sometimes remains difficult and requires systemic therapies. It is hoped that a better knowledge of the regulation of the autoimmune response in BP also will facilitate the design of novel immunomodulatory therapeutic approaches devoid of the severe side effects of current immunosuppressive treatments.
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Affiliation(s)
- Giovanni Di Zenzo
- Molecular and Cell Biology Laboratory, Istituto Dermopatico dell'Immacolata, IDI-IRCCS, Via Monti di Creta 104, 00167 Rome, Italy.
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154
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Long HA, Boczonadi V, McInroy L, Goldberg M, Määttä A. Periplakin-dependent re-organisation of keratin cytoskeleton and loss of collective migration in keratin-8-downregulated epithelial sheets. J Cell Sci 2006; 119:5147-59. [PMID: 17158917 DOI: 10.1242/jcs.03304] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Collective migration of epithelial sheets requires maintenance of cell-cell junctions and co-ordination of the movement of the migrating front. We have investigated the role of keratin intermediate filaments and periplakin, a cytoskeletal linker protein, in the migration of simple epithelial cells. Scratch wounding induces bundling of keratins into a cable of tightly packed filaments adjacent to the free wound edge. Keratin re-organisation is preceded by a re-distribution of periplakin away from the free wound edge. Periplakin participates with dynamic changes in the keratin cytoskeleton via its C-terminal linker domain that co-localises with okadaic-acid-treated keratin granules. Stable expression of the periplakin C-terminal domain increases keratin bundling and Ser431 keratin phosphorylation at wound edge resulting in a delay in wound closure. Ablation of periplakin by siRNA inhibits keratin cable formation and impairs wound closure. Knockdown of keratin 8 with siRNA results in (1) a loss of desmoplakin localisation at cell borders, (2) a failure of MCF-7 epithelial sheets to migrate as a collective unit and (3) accelerated wound closure in vimentin-positive HeLa and Panc-1 cell lines. Thus, keratin 8 is required for the maintenance of epithelial integrity during migration and periplakin participates in the re-organisation of keratins in migrating cells.
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Affiliation(s)
- Heather A Long
- Centre for Stem Cell Research and Regenerative Medicine, School of Biological and Biomedical Sciences, University of Durham, Durham, DH1 3LE, UK
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155
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Jefferson JJ, Leung CL, Liem RKH. Dissecting the sequence specific functions of alternative N-terminal isoforms of mouse bullous pemphigoid antigen 1. Exp Cell Res 2006; 312:2712-25. [PMID: 16797530 DOI: 10.1016/j.yexcr.2006.04.025] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Revised: 04/05/2006] [Accepted: 04/06/2006] [Indexed: 11/21/2022]
Abstract
Bullous pemphigoid antigen 1 (BPAG1) is a member of the plakin family of proteins that is involved in cross-linking the cytoskeletal elements and attaching them to cell junctions. BPAG1 null mice develop severe degeneration of sensory neurons that was attributed in part due to the absence of a splice variant called BPAG1a that harbors an actin-binding domain at the N-terminus. Additional alternative splicing also results in BPAG1a isoforms with different first exons, leading to three additional types of BPAG1a called isoforms 1, 2 and 3 (or BPAG1a1, BPAG1a2, and BPAG1a3). These unique N-terminal extensions of the BPAG1a isoforms are of variable length. In this study, we characterized these N-terminal isoforms and evaluated the influence of these unique N-terminal sequences to the actin-binding properties. The unique N-terminal region of isoform 1 is very short and was not expected to affect the property of the ABD that followed it. In contrast, transfection studies and mutagenesis analyses signified that the N-terminal sequences of isoform 2 had the ability to bundle actin filaments and the N-terminal region that contained isoform 3 showed cortical localization. Isoforms 1, 2 and 3 also displayed differential tissue expression profiles. Taken together, these data suggested that the unique N-terminal regions of these isoforms have different roles that may be tailored to meet tissue specific functions.
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Affiliation(s)
- Julius J Jefferson
- Department of Pathology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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156
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Wilhelmsen K, Litjens SHM, Sonnenberg A. Multiple functions of the integrin alpha6beta4 in epidermal homeostasis and tumorigenesis. Mol Cell Biol 2006; 26:2877-86. [PMID: 16581764 PMCID: PMC1446957 DOI: 10.1128/mcb.26.8.2877-2886.2006] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Kevin Wilhelmsen
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
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157
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Foureur N, Mignot S, Senet P, Verpillat P, Picard-Dahan C, Crickx B, Labarre C, Nicaise-Roland P, Descamps V. Corrélation entre présence d’anticorps anti-antigène de type 2 de la pemphigoïde et démence chez les sujets âgés sans manifestation clinique de pemphigoïde. Ann Dermatol Venereol 2006; 133:439-43. [PMID: 16760830 DOI: 10.1016/s0151-9638(06)70935-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Pemphigoid is a form of auto-immune bullous dermatosis characterised by the production of antibodies directed against components of hemidesmosomes in the basal membrane. The physiopathological process responsible for unmasking of these antigens is unknown. Pemphigoid is more common in elderly subjects and is most often seen in debilitated subjects. The prevalence of pemphigoid anti-pemphigoid antibodies (anti-PB) is not known in the elderly population presenting no dermatological signs evocative of the disease. We studied the prevalence of anti-PBAg2 antibodies in elderly subjects with no signs of pemphigoid as well as in the correlation between the presence of these antibodies and diagnosis of dementia. PATIENTS AND METHODS Elderly subjects (aged over 69 years) with no signs of pemphigoid were recruited consecutively in dermatology and geriatrics departments (138 subjects). Details of concomitant medication were recorded for all subjects and clinical examination was performed with calculation of MMS (Mini Mental Score). The subjects were then divided into two groups based on MMS score. The first group comprised subjects without dementia (MMS > 24) while the second comprised subjects with dementia. Serum anti-PBAg2 antibodies were determined by ELISA and indirect immunofluorescence with confirmation by Western blot. Antinuclear antibodies, used as a control for non-specific immune response, were assayed in all serum samples. The prevalence of these antibodies was compared between the two groups. RESULTS The two groups were comparable in terms of age, sex and presence of dermatological diseases (ulcers, bedsores, erysipelas). Each group comprised 69 subjects. The overall presence of anti-PBAg2 antibodies in subjects with no signs are suggestive of pemphigoid was 3.6%. Presence of anti-PBAg2 antibodies was associated with diagnosis of dementia (p=0.04; 0% and 7% in groups 1 and 2, respectively). No correlation was seen between the presence of anti-PBAg2 antibodies and concomitant medication or dermatological disease. The overall prevalence of antinuclear antibodies was 14.5% and the figure was similar between the two groups. DISCUSSION The presence of anti-PBAg2 could be associated with the diagnosis of dementia in elderly subjects.
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Affiliation(s)
- N Foureur
- Service de Gérontologie, Hôpital Charles Foix, Assistance Publique, Hôpitaux de Paris, Ivry-sur-Seine
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158
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Lalonde R, Strazielle C. Spontaneous and induced mouse mutations with cerebellar dysfunctions: behavior and neurochemistry. Brain Res 2006; 1140:51-74. [PMID: 16499884 DOI: 10.1016/j.brainres.2006.01.031] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Accepted: 01/12/2006] [Indexed: 11/20/2022]
Abstract
Grid2(Lc) (Lurcher), Grid2(ho) (hot-foot), Rora(sg) (staggerer), nr (nervous), Agtpbp1(pcd) (Purkinje cell degeneration), Reln(rl) (reeler), and Girk2(Wv) (Weaver) are spontaneous mutations with cerebellar atrophy, ataxia, and deficits in motor coordination tasks requiring balance and equilibrium. In addition to these signs, the Dst(dt) (dystonia musculorum) spinocerebellar mutant displays dystonic postures and crawling. More recently, transgenic models with human spinocerebellar ataxia mutations and alterations in calcium homeostasis have been shown to exhibit cerebellar anomalies and motor coordination deficits. We describe neurochemical characteristics of these mutants with respect to regional brain metabolism as well as amino acid and biogenic amine concentrations, uptake sites, and receptors.
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Affiliation(s)
- R Lalonde
- Université de Rouen, Faculté de Médecine et de Pharmacie, INSERM U614, 76183 Rouen Cedex, France.
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159
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Wilhelmsen K, Litjens SHM, Kuikman I, Tshimbalanga N, Janssen H, van den Bout I, Raymond K, Sonnenberg A. Nesprin-3, a novel outer nuclear membrane protein, associates with the cytoskeletal linker protein plectin. ACTA ACUST UNITED AC 2006; 171:799-810. [PMID: 16330710 PMCID: PMC2171291 DOI: 10.1083/jcb.200506083] [Citation(s) in RCA: 364] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Despite their importance in cell biology, the mechanisms that maintain the nucleus in its proper position in the cell are not well understood. This is primarily the result of an incomplete knowledge of the proteins in the outer nuclear membrane (ONM) that are able to associate with the different cytoskeletal systems. Two related ONM proteins, nuclear envelope spectrin repeat (nesprin)–1 and –2, are known to make direct connections with the actin cytoskeleton through their NH2-terminal actin-binding domain (ABD). We have now isolated a third member of the nesprin family that lacks an ABD and instead binds to the plakin family member plectin, which can associate with the intermediate filament (IF) system. Overexpression of nesprin-3 results in a dramatic recruitment of plectin to the nuclear perimeter, which is where these two molecules are colocalized with both keratin-6 and -14. Importantly, plectin binds to the integrin α6β4 at the cell surface and to nesprin-3 at the ONM in keratinocytes, suggesting that there is a continuous connection between the nucleus and the extracellular matrix through the IF cytoskeleton.
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Affiliation(s)
- Kevin Wilhelmsen
- Division of Cell Biology, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
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160
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Spazierer D, Fuchs P, Reipert S, Fischer I, Schmuth M, Lassmann H, Wiche G. Epiplakin is dispensable for skin barrier function and for integrity of keratin network cytoarchitecture in simple and stratified epithelia. Mol Cell Biol 2006; 26:559-68. [PMID: 16382147 PMCID: PMC1346901 DOI: 10.1128/mcb.26.2.559-568.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Epiplakin, a giant epithelial protein of >700 kDa, belongs to the plakin family of cytolinker proteins. It represents an atypical family member, however, as it consists entirely of plakin repeat domains but lacks any of the other domains commonly shared by plakins. Hence, its putative function as a cytolinker protein remains to be shown. To investigate epiplakin's biological role, we generated epiplakin-deficient mice by gene targeting in embryonic stem cells. Epiplakin-deficient mice were viable and fertile, without developing any discernible phenotype. Ultrastructurally, their epidermis revealed no differences compared to wild-type littermates, and cornified envelopes isolated from skin showed no alterations in shape or stability. Furthermore, neither embryonal formation nor later function of the epithelial barrier was affected. In primary cultures of epiplakin-deficient keratinocytes, the organization of actin filaments, microtubules, and keratin networks was found to be normal. Similarly, no alterations in keratin network organization were observed in simple epithelia of small intestine and liver or in primary hepatocytes. We conclude that, despite epiplakin's abundant and highly specific expression in stratified and simple epithelia, its absence in mice does not lead to severe skin dysfunctions, nor has it detectable consequences for keratin filament organization and cytoarchitecture of cells.
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Affiliation(s)
- Daniel Spazierer
- Department of Molecular Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohrgasse 9, A-1030 Vienna, Austria
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161
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Goto M, Sumiyoshi H, Sakai T, Fässler R, Ohashi S, Adachi E, Yoshioka H, Fujiwara S. Elimination of epiplakin by gene targeting results in acceleration of keratinocyte migration in mice. Mol Cell Biol 2006; 26:548-58. [PMID: 16382146 PMCID: PMC1346887 DOI: 10.1128/mcb.26.2.548-558.2006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epiplakin (EPPK) was originally identified as a human epidermal autoantigen. To identify the function of epiplakin, we generated epiplakin "knockout" mice. These mice developed normally, with apparently normal epidermis and hair. Electron microscopy after immunostaining revealed the presence of EPPK adjacent to keratin filaments in wild-type mice, suggesting that epiplakin might associate with keratin. The appearance and localization of keratin bundles in intact epidermal keratinocytes of EPPK-/- mice were similar to those in wild-type mice. Wounds on the backs of EPPK-/- mice closed more rapidly than those on the backs of wild-type and heterozygous mice. The outgrowth of keratinocytes from skin explants from knockout mice was enhanced compared to outgrowth from explants from wild-type mice, even in the presence of mitomycin C, suggesting that the difference in keratinocyte outgrowth might be due to a difference in the speed of migration of keratinocytes. At wound edges in wild-type mice, EPPK was expressed in proliferating keratinocytes in conjunction with keratin 6. In EPPK-/- mice, no similar proliferating keratinocytes were observed, but migrating keratinocytes weakly expressed keratin 6. EPPK was coexpressed with keratin 6 in some keratinocytes in explant cultures from wild mice. We propose that EPPK might be linked functionally with keratin 6.
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Affiliation(s)
- Mizuki Goto
- Department of Anatomy, Biology and Medicine (Dermatology and Biochemistry), Faculty of Medicine, Oita University, Idaigaoka 1-1, Hasama-machi, Yufu 879-5593, Japan
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162
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Thoma-Uszynski S, Uter W, Schwietzke S, Schuler G, Borradori L, Hertl M. Autoreactive T and B cells from bullous pemphigoid (BP) patients recognize epitopes clustered in distinct regions of BP180 and BP230. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2006; 176:2015-23. [PMID: 16424234 DOI: 10.4049/jimmunol.176.3.2015] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Bullous pemphigoid (BP) is a well-characterized model of autoantibody-mediated autoimmunity, which presumably depends on autoreactive Th cells that promote the activation of autoreactive B cells. The two major autoantigens of BP are BP180 and BP230, two components of dermoepidermal adhesion complexes. Both, autoreactive Th cell responses and autoantibody profiles were characterized in 35 patients with acute onset BP using BP180 and BP230 proteins. Our findings indicate the following: 1) autoreactive Th cells recognized epitopes within the NH2-terminal (77.1%), COOH-terminal (65.7%), and central portion (57.1%) of the BP180 ectodomain; 2) IgG autoantibodies were found to exhibit similar or identical reactivity against the NH2-terminal (82.8%), COOH-terminal (77.1%), and central portion (37.1%) of the BP180 ectodomain; 3) T and B cell reactivity with the NH2-terminal portion of the BP180 ectodomain was associated with extensive BP, whereas the central portion was more frequently recognized in limited BP; 4) only 7 of 16 (43.7%) and 6 of 16 (37.5%) BP patients showed a Th cellular response against the COOH- and NH2-terminal regions of BP230, respectively, whereas 5) IgG reactivity against the COOH- and NH2-termini of BP230 was detected in 5 of 16 (31.3%) and 6 of 16 (37.5%) patients, respectively. These results demonstrate that Th and B cell reactivities against BP180, are, in contrast to BP230 reactivity, almost constantly detectable in BP patients, and differential epitope recognition of BP180 seems to be associated with distinct clinical severity. These observations support the concept that BP180, but not BP230, is the primary autoantigen of BP critical for disease development.
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163
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Pool M, Boudreau Larivière C, Bernier G, Young KG, Kothary R. Genetic alterations at the Bpag1 locus in dt mice and their impact on transcript expression. Mamm Genome 2005; 16:909-17. [PMID: 16341670 DOI: 10.1007/s00335-005-0073-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Accepted: 08/23/2005] [Indexed: 10/25/2022]
Abstract
The dystonin/Bpag1 gene encodes several tissue-specific alternatively spliced transcripts that encode cytoskeletal binding proteins. These various isoforms are necessary for maintaining the structural integrity of epithelial, neural, and muscle tissues. Mutations in the dystonin/Bpag1 gene cause dystonia musculorum (dt), a hereditary neuropathy of the mouse characterized by the progressive degeneration of sensory neurons. Several dt mutant alleles exist, most of which have arisen through spontaneous mutations. In this article we demonstrate that the dt locus encodes 107 exons spanning 400 kb. The high frequency of occurrence of spontaneous dt mutants may therefore be a result of the large size of the gene. Analysis of genomic DNA from several dt spontaneous mutant alleles, dt(24J), dt(27J), dt(Alb), and dt(Frk), shows a deletion of the central portion of the gene in dt(Alb) but no large rearrangements or deletions in the other alleles. These other alleles likely have small deletions or rearrangements, or point mutations. To determine the impact of the known and unknown mutations on transcript levels, RT-PCR was performed to detect various coding regions of the dystonin/Bpag1 transcripts in brain and muscle from multiple dt alleles: dt(Tg4), dt(Alb), dt(24J), dt(27J), and dt(Frk). With the exception of dt(Frk), reduced transcript levels were observed for all alleles tested. Such alterations likely result in reduced or absent dystonin/Bpag1 protein levels. Thus, distinct genetic defects lead to a common outcome of reduced transcript expression causing the same phenotype in multiple dt alleles.
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Affiliation(s)
- Madeline Pool
- Molecular Medicine Program, Ottawa Health Research Institute, Ottawa, Ontario, K1H 8L6, Canada
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164
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Huang CM, Elmets CA, van Kampen KR, Desilva TS, Barnes S, Kim H, Tang DCC. Prospective highlights of functional skin proteomics. MASS SPECTROMETRY REVIEWS 2005; 24:647-660. [PMID: 15376279 DOI: 10.1002/mas.20037] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Although a wide variety of protein profiles have been extensively constructed via proteomic analysis, the comprehensive proteomic profiling of the skin, which is considered to be the largest organ of the human body, is still far from complete. Our efforts to establish the functional skin proteome, a protein database describing the protein networks that underlie biological processes, has set in motion the identification and characterization of proteins expressed in the epidermis and dermis of the BALB/c mice. In this review, we will highlight various cutaneous proteins we have characterized and discuss their biological functions associated with skin distress, immunity, and cancer. This type of research into functional skin proteomics will provide a critical step toward understanding disease and developing successful therapeutic strategies.
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Affiliation(s)
- Chun-Ming Huang
- Department of Dermatology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
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165
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Lalonde R, Marchetti N, Strazielle C. Primary neurologic screening and motor coordination of Dstdt-J mutant mice (dystonia musculorum) with spinocerebellar atrophy. Physiol Behav 2005; 86:46-51. [PMID: 16087202 DOI: 10.1016/j.physbeh.2005.06.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2005] [Revised: 05/30/2005] [Accepted: 06/20/2005] [Indexed: 11/27/2022]
Abstract
The autosomal recessive dystonia musculorum (Dst(dt-J)) mutation causes degenerative lesions of peripheral and central sensory pathways. A test battery of motor, sensory, postural, and autonomic functions was used to compare young control and homozygous Dst(dt-J) mice. The Dst(dt-J) mutants were severely impaired for muscle strength, limb coordination, and postural reflexes. As a result of a loss in motor control, the mutants were hypoactive in the open-field and fell quickly from the stationary beam. In sensory tests, the acoustic startle response was impaired, but not tactile reflexes and contact righting, attesting to preserved labyrinthine function and non-lemniscal pathways. Dst(dt-J) mutants were also distinguishable from controls on the basis of tremor, a paler skin, piloerection, and half-open eyes, as well as low body weight and fecal boli. Grooming episodes were less frequent in the mutants but without any reduction in grooming time. The neurologic screening battery delineated the functional integrity of some sensorimotor pathways in a spinocerebellar mutant whose severe phenotype prevents a more elaborate evaluation.
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Affiliation(s)
- R Lalonde
- Université de Rouen, Faculté de Médecine et de Pharmacie, INSERM U614, Bâtiment de Recherche, Salle 1D18, France.
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166
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Abstract
Injury to the skin initiates a cascade of events including inflammation, new tissue formation, and tissue remodeling, that finally lead to at least partial reconstruction of the original tissue. Historically, animal models of repair have taught us much about how this repair process is orchestrated and, over recent years, the use of genetically modified mice has helped define the roles of many key molecules. Aside from conventional knockout technology, many ingenious approaches have been adopted, allowing researchers to circumvent such problems as embryonic lethality, or to affect gene function in a tissue- or temporal-specific manner. Together, these studies provide us with a growing source of information describing, to date, the in vivo function of nearly 100 proteins in the context of wound repair. This article focuses on the studies in which genetically modified mouse models have helped elucidate the roles that many soluble mediators play during wound repair, encompassing the fibroblast growth factor (FGF) and transforming growth factor-beta (TGF-beta) families and also data on cytokines and chemokines. Finally, we include a table summarizing all of the currently published data in this rapidly growing field. For a regularly updated web archive of studies, we have constructed a Compendium of Published Wound Healing Studies on Genetically Modified Mice which is avaialble at http://icbxs.ethz.ch/members/grose/woundtransgenic/home.html.
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Affiliation(s)
- Richard Grose
- London Research Institute Lab 214, Cancer Research UK, 61 Lincoln's Inn Fields, London WC2A 3PX, UK.
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167
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Jang SI, Kalinin A, Takahashi K, Marekov LN, Steinert PM. Characterization of human epiplakin: RNAi-mediated epiplakin depletion leads to the disruption of keratin and vimentin IF networks. J Cell Sci 2005; 118:781-93. [PMID: 15671067 DOI: 10.1242/jcs.01647] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epiplakin is a member of the plakin family with multiple copies of the plakin repeat domain (PRD). We studied the subcellular distribution and interactions of human epiplakin by immunostaining, overlay assays and RNAi knockdown. Epiplakin decorated the keratin intermediate filaments (IF) network and partially that of vimentin. In the binding assays, the repeat unit (PRD plus linker) showed strong binding and preferentially associated with assembled IF over keratin monomers. Epiplakin knockdown revealed disruption of IF networks in simple epithelial but not in epidermal cells. In rescue experiments, the repeat unit was necessary to prevent the collapse of IF networks in transient knockdown; however, it could only partially restore the keratin but not the vimentin IF network in stably knocked down HeLa cells. We suggest that epiplakin is a cytolinker involved in maintaining the integrity of IF networks in simple epithelial cells. Furthermore, we observed an increase of epiplakin expression in keratinocytes after the calcium switch, suggesting the involvement of epiplakin in the process of keratinocyte differentiation.
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Affiliation(s)
- Shyh-Ing Jang
- Laboratory of Skin Biology, NIAMS, National Institutes of Health, Bethesda, MD 20892-8023, USA
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168
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Goryunov D, Leung CL, Liem RKH. Studying cytolinker proteins. Methods Cell Biol 2005; 78:787-816. [PMID: 15646639 DOI: 10.1016/s0091-679x(04)78027-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Affiliation(s)
- Dmitry Goryunov
- Columbia University College of Physicians and Surgeons, New York, New York 10032, USA
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169
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170
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Green KJ, Böhringer M, Gocken T, Jones JCR. Intermediate filament associated proteins. ADVANCES IN PROTEIN CHEMISTRY 2005; 70:143-202. [PMID: 15837516 DOI: 10.1016/s0065-3233(05)70006-1] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Intermediate filament associated proteins (IFAPs) coordinate interactions between intermediate filaments (IFs) and other cytoskeletal elements and organelles, including membrane-associated junctions such as desmosomes and hemidesmosomes in epithelial cells, costameres in striated muscle, and intercalated discs in cardiac muscle. IFAPs thus serve as critical connecting links in the IF scaffolding that organizes the cytoplasm and confers mechanical stability to cells and tissues. However, in recent years it has become apparent that IFAPs are not limited to structural crosslinkers and bundlers but also include chaperones, enzymes, adapters, and receptors. IF networks can therefore be considered scaffolding upon which associated proteins are organized and regulated to control metabolic activities and maintain cell homeostasis.
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Affiliation(s)
- Kathleen J Green
- Departments of Pathology and Dermatology and R.H. Lurie Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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171
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Aho S, Li K, Ryoo Y, McGee C, Ishida-Yamamoto A, Uitto J, Klement JF. Periplakin gene targeting reveals a constituent of the cornified cell envelope dispensable for normal mouse development. Mol Cell Biol 2004; 24:6410-8. [PMID: 15226441 PMCID: PMC434234 DOI: 10.1128/mcb.24.14.6410-6418.2004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The members of the plakin family of proteins serve as epidermal cytolinkers and components of cell-cell and cell-matrix adhesion complexes, i.e., desmosomes and hemidesmosomes, respectively. Periplakin is a recently characterized member of this family. Human and mouse periplakin genomic loci are conserved, and the proteins are highly homologous, suggesting a role for periplakin in vertebrate physiology. In order to evaluate the functional role of periplakin, we generated periplakin null mice through targeted homologous recombination of mouse embryonic stem cells, followed by development of Ppl(-/-) mice. Mice homozygous for the targeted allele were born in the expected Mendelian frequency, developed normally, possessed grossly normal epidermis and hair, and were healthy and fertile. The epidermal barrier appeared to develop normally during fetal days E15.5 to E16.5, and the cornified envelope and desmosomes in the newborn mice were ultrastructurally normal. No compensatory increase in the expression of other epithelial proteins was detected in the neonatal mouse epidermis lacking periplakin. Consequently, the primary role of periplakin may not relate to the physiology of the cornified cell envelope in epidermal keratinocytes but may reside in the challenges, which normal laboratory mice do not encounter.
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Affiliation(s)
- Sirpa Aho
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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172
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Jefferson JJ, Leung CL, Liem RKH. Plakins: goliaths that link cell junctions and the cytoskeleton. Nat Rev Mol Cell Biol 2004; 5:542-53. [PMID: 15232572 DOI: 10.1038/nrm1425] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Julius J Jefferson
- Department of Pathology, Columbia University College of Physicians & Surgeons, 630 West 168th Street, New York 10032, USA
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173
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Abstract
Intermediate filaments, actin-containing microfilaments and microtubules are the three main cytoskeletal systems of vertebrate and many invertebrate cells. Although these systems are composed of distinctly different proteins, they are in constant and intimate communication with one another. Understanding the molecular basis of this cytoskeletal crosstalk is essential for determining the mechanisms that underlie many cell-biological phenomena. Recent studies have revealed that intermediate filaments and their associated proteins are important components in mediating this crosstalk.
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Affiliation(s)
- Lynne Chang
- Feinberg School of Medicine, Northwestern University, Department of Cell and Molecular Biology, 303 East Chicago Avenue, Chicago, Illinois 60611, USA.
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174
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Thoma-Uszynski S, Uter W, Schwietzke S, Hofmann SC, Hunziker T, Bernard P, Treudler R, Zouboulis CC, Schuler G, Borradori L, Hertl M. BP230- and BP180-specific auto-antibodies in bullous pemphigoid. J Invest Dermatol 2004; 122:1413-22. [PMID: 15175032 DOI: 10.1111/j.0022-202x.2004.22603.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Bullous pemphigoid is a subepidermal blistering disease associated with auto-antibodies (auto-ab) to BP180 and BP230. We developed ELISAs utilizing baculovirus-encoded recombinant proteins of BP230 and BP180 and studied their diagnostic and prognostic values by assessing the profile of the auto-ab response in 127 patients with BP. 39 patients had focal involvement, whereas 88 had generalized disease; 51 individuals served as controls. The results indicate: (1) BP180 IgG reactivity was associated with an overall sensitivity of 0.953 and specificity of 0.940; (2) 105 of 127 BP patients also displayed BP230 auto-reactivity, the global diagnostic performance of which, however, was moderate compared to BP180-auto-reactivity (sensitivity 0.815 vs 0.953, specificity 0.648 vs 0.940); (3) 101 patients (79.5%) had concordant BP180 and BP230 reactivity; (4) the association between the presence of BP230 auto-reactivity and focal involvement was stronger than in generalized disease (odds ratio (OR) 17.7 vs 10.2), independently from BP180 auto-ab profile; (5) correlation of total IgG with IgG1 and IgG4 was variable for both BP180 and BP230. Collectively, the global diagnostic properties of the BP180-ELISA outperform those of the BP230-ELISA. Presence of BP230 auto-reactivity, however, supports the diagnosis of BP and might be indicative for the extent of the disease.
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175
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Lalonde R, Strazielle C. The effects of cerebellar damage on maze learning in animals. THE CEREBELLUM 2004; 2:300-9. [PMID: 14964689 DOI: 10.1080/14734220310017456] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The role of the cerebellum in spatial learning has recently been investigated in genetically and non-genetically lesioned animal models, particularly in water mazes, in view of the minimal impact such lesions exert on swimming movements. A dissociation between place and cued learning in the Morris water maze has been observed in several models, including cerebellar mutant mice (Rora(sg), Nna1(pcd-1J), nervous), rats with lesions of either the lateral cerebellar cortex or the dentate nucleus, and rats with selective Purkinje cell loss caused by intracerebroventricular injections of OX-7-saporin, confirming the hypothesis that cerebellar damage may cause a cognitive deficit independently of fine motor control. In addition, the results of hemicerebellectomized rats indicate the probable involvement of the cerebellum in working memory and the procedural aspect of maze learning. The findings of impaired maze learning in cerebellar-lesioned mice and rats are concordant with those of deficient visuospatial functions in patients with cerebellar atrophy. The spatial deficits may be ascribed to altered metabolic activity in cerebellar-related pathways.
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Affiliation(s)
- R Lalonde
- Hôtel-Dieu du Centre Hospitalier de l'Université de Montréal, Service de Neurologie, 3840 St-Urbain, Montréal, Québec, Canada.
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176
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Abstract
For many years, cytoplasmic intermediate filaments (IFs) were considered to be stable cytoskeletal elements contributing primarily to the maintenance of the structural and mechanical integrity of cells. However, recent studies of living cells have revealed that IFs and their precursors possess a remarkably wide array of dynamic and motile properties. These properties are in large part due to interactions with molecular motors such as conventional kinesin, cytoplasmic dynein, and myosin. The association between IFs and motors appears to account for much of the well-documented molecular cross talk between IFs and the other major cytoskeletal elements, microtubules, and actin-containing microfilaments. Furthermore, the associations with molecular motors are also responsible for the high-speed, targeted delivery of nonfilamentous IF protein cargo to specific regions of the cytoplasm where they polymerize into IFs. This review considers the functional implications of the motile properties of IFs and discusses the potential relationships between malfunctions in these motile activities and human diseases.
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Affiliation(s)
- Brian T Helfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA.
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177
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Koster J, Borradori L, Sonnenberg A. Hemidesmosomes: molecular organization and their importance for cell adhesion and disease. Handb Exp Pharmacol 2004:243-280. [PMID: 20455096 DOI: 10.1007/978-3-540-68170-0_9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
In the skin, basal epithelial cells constantly divide to renew the epidermis. The newly formed epithelial cells then differentiate in a process called keratinization, ultimately leading to the death of these cells and a pile-up of cell material containing vast amounts of keratins. The basal keratinocytes in skin are attached to their underlying basement membrane via specialized adhesion complexes termed hemidesmosomes (HDs). These complexes ascertain stable adhesion of the epidermis to the dermis, and mutations in components of these complexes often result in tissue fragility and blistering of the skin. In this review, we will describe the various hemidesmosomal proteins in detail as well as, briefly, the protein families to which they belong. Specifically, we will report the protein-protein interactions involved in the assembly of hemidesmosomes and their molecular organization. Some signaling pathways involving primarily the alpha6beta4 integrin will be discussed, since they appear to profoundly modulate the assembly and function of hemidesmosomes. Furthermore, the importance of these hemidesmosomal components for the maintenance of tissue homeostasis and their involvement in various clinical disorders will be emphasized. Finally, we will present a model for the assembly of HDs, based on our present knowledge.
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Affiliation(s)
- J Koster
- Division of Cell Biology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
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178
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Fontao L, Tasanen K, Huber M, Hohl D, Koster J, Bruckner-Tuderman L, Sonnenberg A, Borradori L. Molecular consequences of deletion of the cytoplasmic domain of bullous pemphigoid 180 in a patient with predominant features of epidermolysis bullosa simplex. J Invest Dermatol 2004; 122:65-72. [PMID: 14962091 DOI: 10.1046/j.0022-202x.2003.22125.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bullous pemphigoid antigen 2 (BP180; COL17A1) collagen gene mutations typically result in nonlethal junctional epidermolysis bullosa. We have identified a patient, who had phenotypic features of mainly epidermolysis bullosa simplex and evidence for both intraepidermal and junctional blister formation. Mutation analysis disclosed compound heterozygous mutations in the COL17A1 gene, leading to deletion of Ile-18 to Asn-407 from the intracellular domain of BP180, BP180 Delta 18-407. To gain insight into the mechanisms underlying the phenotype, we have investigated the functional consequences of this truncation in BP180. The results demonstrate that: (1) in cultured keratinocytes of the patient, the assembly of hemidesmosomes, and their linkage with intermediate filaments are impaired; (2) BP180 Delta 18-407 is not capable of binding to the hemidesmosomal components BP230, plectin, and the beta 4 subunit of the alpha 6 beta 4 integrin in yeast two-hybrid assays; (3) BP180 Delta 18-407 is recruited into hemidesmosome-like structures in both normal and BP180-deficient transfected keratinocytes when ectopically expressed, suggesting that the extracellular domain of BP180 Delta 18-407 determines its topogenic fate; and, finally (4) the proteolytic shedding of the extracellular domain of BP180 Delta 18-407 is not impaired in transfected COS-7 cells. Collectively, the data demonstrate that the truncation of the intracellular domain of BP180 impairs the organization of hemidesmosomes, affecting both the mechanical stability of basal keratinocytes and dermoepidermal cohesion.
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Affiliation(s)
- Lionel Fontao
- Department of Dermatology, University Hospital, Geneva, Switzerland
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179
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Tsuruta D, Jones JCR. The vimentin cytoskeleton regulates focal contact size and adhesion of endothelial cells subjected to shear stress. J Cell Sci 2003; 116:4977-84. [PMID: 14625391 DOI: 10.1242/jcs.00823] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Recently, we reported that vimentin-type intermediate filaments, in addition to microfilaments, associate with αvβ3 integrin-positive focal contacts in endothelial cells. To gain insight into intermediate filament-focal contact interaction, we induced expression of yellow fluorescent protein (YFP)-integrin β3 and cyan fluorescent protein (CFP)-vimentin protein in endothelial cells. At least 50% of the YFP-β3 integrin-labeled focal contacts associated with CFP-labeled vimentin intermediate filaments in live cells. Moreover, focal contacts and intermediate filaments moved in concert in the plane of the membrane and assembling focal contacts were sites of vimentin filament assembly. When endothelial cells were subjected to flow, large focal contacts assembled and associated with thick vimentin bundles. These large focal contacts showed minimal dynamic activity. Cells in which vimentin expression had been inhibited by RNA interference assembled smaller than normal focal contacts. More dramatically, such cells showed decreased adhesion to the substratum. These data provide evidence that the vimentin cytoskeleton regulates focal contact size and helps stabilize cell-matrix adhesions in endothelial cells.
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Affiliation(s)
- Daisuke Tsuruta
- Department of Cell and Molecular Biology, Northwestern University Medical School, Morton 4-616, 303 E. Chicago Avenue, Chicago, IL 60611, USA
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180
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Koster J, van Wilpe S, Kuikman I, Litjens SHM, Sonnenberg A. Role of binding of plectin to the integrin beta4 subunit in the assembly of hemidesmosomes. Mol Biol Cell 2003; 15:1211-23. [PMID: 14668477 PMCID: PMC363110 DOI: 10.1091/mbc.e03-09-0697] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
We have previously shown that plectin is recruited into hemidesmosomes through association of its actin-binding domain (ABD) with the first pair of fibronectin type III (FNIII) repeats and a small part of the connecting segment (residues 1328-1355) of the integrin beta4 subunit. Here, we show that two proline residues (P1330 and P1333) in this region of the connecting segment are critical for supporting beta4-mediated recruitment of plectin. Additional binding sites for the plakin domain of plectin on beta4 were identified in biochemical and yeast two-hybrid assays. These sites are located at the end of the connecting segment (residues 1383-1436) and in the region containing the fourth FNIII repeat and the C-tail (residues 1570-1752). However, in cells, these additional binding sites cannot induce the assembly of hemidesmosomes without the interaction of the plectin-ABD with beta4. Because the additional plectin binding sites overlap with sequences that mediate an intramolecular association of the beta4 cytoplasmic domain, we propose that they are not accessible for binding and need to become exposed as the result of the binding of the plectin-ABD to beta4. Furthermore, these additional binding sites might be necessary to position the beta4 cytoplasmic domain for an optimal interaction with other hemidesmosomal components, thereby increasing the efficiency of hemidesmosome assembly.
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Affiliation(s)
- J Koster
- The Netherlands Cancer Institute, Division of Cell Biology, 1066 CX Amsterdam, The Netherlands
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181
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Young KG, Pool M, Kothary R. Bpag1 localization to actin filaments and to the nucleus is regulated by its N-terminus. J Cell Sci 2003; 116:4543-55. [PMID: 14576348 DOI: 10.1242/jcs.00764] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Plakins are a family of giant cytoskeleton binding proteins. One member of this group is bullous pemphigoid antigen 1 (Bpag1)/dystonin, which has neuronal and muscle isoforms that consist of actin-binding and microtubule-binding domains at either end separated by a plakin domain and several spectrin repeats. The better-characterized epithelial isoform has only the plakin domain in common with the neuronal and muscle isoforms. Here, we have analyzed the localization of muscle/neuronal (Bpag1a/b) isoforms and the epithelial (Bpag1e) isoform within C2C12 myoblast cells. Although an antibody specific to Bpag1a/b isoform 2 detected protein co-aligning actin stress fibers, this same antibody and two Bpag1e antibodies predominantly detected protein in the nuclei. A Bpag1a/b isoform 2 N-terminal fusion protein containing the plakin domain also localized to actin stress fibers and to nuclei. Within the plakin domain, we characterized a functional nuclear localization signal, which was responsible for localization of the fusion protein to the nucleus. Bpag1a/b isoform 1 N-terminal fusion proteins differed in their interaction with the actin cytoskeleton and with their ability to localize to the nucleus, suggesting that Bpag1 isoforms with different N-termini have differing roles. These results show the importance of N-terminal domains in dictating the localization and function of Bpag1 isoforms. We provide the first indication that Bpag1 is not strictly a cytoplasmic/membrane protein but that it can also localize to the nucleus.
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Affiliation(s)
- Kevin G Young
- Ottawa Health Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6, and Center for Neuromuscular Disease, and Departments of Cellular and Molecular Medicine, and Medicine, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
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182
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Röper K, Brown NH. Maintaining epithelial integrity: a function for gigantic spectraplakin isoforms in adherens junctions. ACTA ACUST UNITED AC 2003; 162:1305-15. [PMID: 14517208 PMCID: PMC2173965 DOI: 10.1083/jcb.200307089] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The Short stop (Shot/Kakapo) spectraplakin is a giant cytoskeletal protein, which exists in multiple isoforms with characteristics of both spectrin and plakin superfamilies. Previously characterized Shot isoforms are similar to spectrin and dystrophin, with an actin-binding domain followed by spectrin repeats. We describe a new large exon within the shot locus, which encodes a series of plakin repeats similar to the COOH terminus of plakins such as plectin and BPAG1e. We find that the plakin repeats are inserted between the actin-binding domain and spectrin repeats, generating isoforms as large as 8,846 residues, which could span 400 nm. These novel isoforms localized to adherens junctions of embryonic and follicular epithelia. Loss of Shot within the follicle epithelium leads to double layering and accumulation of actin and ZO-1 in between, and a reduction of Armadillo and Discs lost within, mutant cells, indicative of a disruption of adherens junction integrity. Thus, we identify a new role for spectraplakins in mediating cell–cell adhesion.
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Affiliation(s)
- Katja Röper
- Wellcome Trust/Cancer Research UK Institute, University of Cambridge, Cambridge, CB2 1QR UK
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183
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Liu JJ, Ding J, Kowal AS, Nardine T, Allen E, Delcroix JD, Wu C, Mobley W, Fuchs E, Yang Y. BPAG1n4 is essential for retrograde axonal transport in sensory neurons. J Cell Biol 2003; 163:223-9. [PMID: 14581450 PMCID: PMC2173519 DOI: 10.1083/jcb.200306075] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2003] [Accepted: 09/15/2003] [Indexed: 11/22/2022] Open
Abstract
Disruption of the BPAG1 (bullous pemphigoid antigen 1) gene results in progressive deterioration in motor function and devastating sensory neurodegeneration in the null mice. We have previously demonstrated that BPAG1n1 and BPAG1n3 play important roles in organizing cytoskeletal networks in vivo. Here, we characterize functions of a novel BPAG1 neuronal isoform, BPAG1n4. Results obtained from yeast two-hybrid screening, blot overlay binding assays, and coimmunoprecipitations demonstrate that BPAG1n4 interacts directly with dynactin p150Glued through its unique ezrin/radixin/moesin domain. Studies using double immunofluorescent microscopy and ultrastructural analysis reveal physiological colocalization of BPAG1n4 with dynactin/dynein. Disruption of the interaction between BPAG1n4 and dynactin results in severe defects in retrograde axonal transport. We conclude that BPAG1n4 plays an essential role in retrograde axonal transport in sensory neurons. These findings might advance our understanding of pathogenesis of axonal degeneration and neuronal death.
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Affiliation(s)
- Jia-Jia Liu
- Department of Neurology, Stanford University School of Medicine, Stanford, CA 94305-5489, USA.
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184
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Herrmann H, Hesse M, Reichenzeller M, Aebi U, Magin TM. Functional complexity of intermediate filament cytoskeletons: from structure to assembly to gene ablation. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 223:83-175. [PMID: 12641211 DOI: 10.1016/s0074-7696(05)23003-6] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The cell biology of intermediate filament (IF) proteins and their filaments is complicated by the fact that the members of the gene family, which in humans amount to at least 65, are differentially expressed in very complex patterns during embryonic development. Thus, different tissues and cells express entirely different sets and amounts of IF proteins, the only exception being the nuclear B-type lamins, which are found in every cell. Moreover, in the course of evolution the individual members of this family have, within one species, diverged so much from each other with regard to sequence and thus molecular properties that it is hard to envision a unifying kind of function for them. The known epidermolytic diseases, caused by single point mutations in keratins, have been used as an argument for a role of IFs in mechanical "stress resistance," something one would not have easily ascribed to the beaded chain filaments, a special type of IF in the eye lens, or to nuclear lamins. Therefore, the power of plastic dish cell biology may be limited in revealing functional clues for these structural elements, and it may therefore be of interest to go to the extreme ends of the life sciences, i.e., from the molecular properties of individual molecules including their structure at the atomic level to targeted inactivation of their genes in living animals, mouse, and worm to define their role more precisely in metazoan cell physiology.
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Affiliation(s)
- Harald Herrmann
- Division of Cell Biology, German Cancer Research Center, D-69120 Heidelberg, Germany
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185
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Spazierer D, Fuchs P, Pröll V, Janda L, Oehler S, Fischer I, Hauptmann R, Wiche G. Epiplakin gene analysis in mouse reveals a single exon encoding a 725-kDa protein with expression restricted to epithelial tissues. J Biol Chem 2003; 278:31657-66. [PMID: 12791695 DOI: 10.1074/jbc.m303055200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Based on cDNA cloning and sequencing, human epiplakin has been classified as a member of the plakin protein family of cytolinkers. We report here the characterization of the mouse epiplakin gene locus and the isolation of full-length mouse epiplakin cDNA using BAC vectors. We found that the protein is encoded by a single remarkably large exon (>20 kb) that consists of a series of 0.8-1.5-kb-long DNA repeats, eight of which are virtually identical. Consequently, mouse epiplakin contains 16 plakin repeat domains, three more than reported for the human protein and eight more than predicted for the mouse protein based on the contig characterized by the Mouse Genome Sequencing Consortium. Using antibodies raised to a highly conserved repeating epiplakin sequence domain, we show that the protein in cells is expressed in its full length (725 kDa), and we provide evidence that the size of human epiplakin previously may have been underestimated. In addition we show on transcript and protein levels that epiplakin is restricted to epithelial tissues and that its gene maps to mouse chromosome 15 (human chromosome 8). This study lays the groundwork for future genetic approaches aimed at defining the biological role of this unique protein.
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Affiliation(s)
- Daniel Spazierer
- Vienna Biocenter, Institute of Biochemistry and Molecular Cell Biology, University of Vienna, A-1030 Vienna, Austria
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186
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De Repentigny Y, Deschênes-Furry J, Jasmin BJ, Kothary R. Impaired fast axonal transport in neurons of the sciatic nerves from dystonia musculorum mice. J Neurochem 2003; 86:564-71. [PMID: 12859670 DOI: 10.1046/j.1471-4159.2003.01861.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dystonia musculorum (dt) mice suffer from a severe sensory neuropathy caused by mutations in the gene encoding the cytoskeletal cross-linker protein dystonin/bullous pemphigoid antigen 1 (Bpag1). Loss of function of dystonin/Bpag1 within neurons leads to a loss in the maintenance of cytoskeletal organization and to the development of focal axonal swellings prior to death of the neuron. In the present study, we demonstrate that neurons within the sciatic nerves of dt27J mice undergo axonal degeneration as has been previously reported for the dorsal roots. Furthermore, ultrastructural studies reveal a perturbed organization of the neurofilament and microtubule networks within the axons of sciatic nerves in dt27J mice. The disrupted cytoskeletal organization suggested that axonal transport is affected in dt mice. To address this, we assessed fast axonal transport by measuring the rate of accumulation of acetylcholinesterase (AChE) proximal and distal to a surgically introduced ligature on the sciatic nerves of normal and dt27J mice. Our findings demonstrate that axonal transport of AChE in both orthograde and retrograde directions is markedly affected, and allow us to conclude that axonal transport defects do exist in the sciatic nerves of dt27J mice.
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187
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Huang CM, Foster KW, DeSilva T, Zhang J, Shi Z, Yusuf N, Van Kampen KR, Elmets CA, Tang DCC. Comparative proteomic profiling of murine skin. J Invest Dermatol 2003; 121:51-64. [PMID: 12839563 DOI: 10.1046/j.1523-1747.2003.12327.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Mammalian skin is regularly exposed to different environmental stresses, each of which results in specific compensatory changes in protein expression that can be assessed by proteomic analysis. We have established a reference proteome map of BALB/c murine skin allowing the resolution of greater than 500 protein spots in a single two-dimensional polyacrylamide gel. Forty-four protein spots, corresponding to 28 different cutaneous proteins, were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and the Mascot online database searching algorithm. Twenty-five proteins were expressed at higher levels in the epidermis, whereas only nine were found predominantly in the subepidermal tissues. A subset of protein spots exhibited strain-specific expression. Proteins of diverse function were identified, including those involved in stress response, apoptosis, growth inhibition, the maintenance of structural integrity, translational control, energy metabolism, calcium binding, cholesterol transport, and the scavenging of free radicals. Prohibitin expression was detected cutaneously, with more abundant protein and mRNA levels in the epidermis. Five molecular chaperones including protein di-sulfide isomerase, 78 kDa glucose-regulated protein precursor, heat shock protein 60 (HSP60), HSP70, and HSP27 were also identified. Of these, HSP27 expression was confined mainly to the epidermis, and expression of protein disulfide isomerase was found primarily in the subepidermal tissues. Proteomic analysis of skin following heat or cold shock resulted in increased levels of HSP27, HSP60, and HSP70 suggesting involvement of these chaperones in the cutaneous response mechanism to temperature stress. These data establish numerous reference markers within the proteome map of murine skin and provide an important framework for future efforts aimed at characterization of the epidermal and subepidermal responses to environmental changes.
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Affiliation(s)
- Chun-Ming Huang
- Department of Dermatology, University of Alabama at Birmingham, USA.
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188
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Werrlein RJ, Madren-Whalley JS. Multiphoton microscopy: an optical approach to understanding and resolving sulfur mustard lesions. JOURNAL OF BIOMEDICAL OPTICS 2003; 8:396-409. [PMID: 12880345 DOI: 10.1117/1.1584687] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Sulfur mustard (SM; 2,2(')-dichloroethyl sulfide) is a percutaneous alkylating agent first used as a chemical weapon at Ypres, Belgium, in World War I. Despite its well-documented history, the primary lesions effecting dermal-epidermal separation and latent onset of incapacitating blisters remain poorly understood. By immunofluorescent imaging of human epidermal keratinocytes (HEK) and epidermal tissues exposed to SM (400 microM for 5 min), we have amassed unequivocal evidence that SM disrupts adhesion complex molecules, which are also disrupted by epidermolysis bullosa-type blistering diseases of the skin. Images of keratin 14 (K14) in control cells showed tentlike filament networks linking the HEK's basolateral anchoring sites to the dorsal surface of its nuclei. Images from 6-h postexposure profiles revealed early disruption (</=1 h) and progressive collapse of the K14 cytoskeleton. Collapse involved focal erosions, loss of functional asymmetry, and displacement of nuclei beneath a mat of jumbled filaments. In complementary studies, 1-h images showed statistically significant (p<0.01) decreases of 25 to 30% in emissions from labeled alpha(6)beta(4) integrin and laminin 5, plus disruption of their receptor-ligand organization. Results indicate that SM alkylation destabilizes dermal-epidermal attachments and potentiates vesication by disrupting adhesion complex molecules and associated signaling mechanisms required for their maintenance and repair.
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Affiliation(s)
- Robert J Werrlein
- U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, Maryland 21010-5400, USA.
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189
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Dunnwald M, Zuberi AR, Stephens K, Le R, Sundberg JP, Fleckman P, Dale BA. The ichq mutant mouse, a model for the human skin disorder harlequin ichthyosis: mapping, keratinocyte culture, and consideration of candidate genes involved in epidermal growth regulation. Exp Dermatol 2003; 12:245-54. [PMID: 12823437 DOI: 10.1034/j.1600-0625.2003.120303.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Harlequin ichthyosis (HI) is a rare and usually fatal scaling skin disorder. The HI mutant mouse (ichq/ichq) has many similarities to the human disorder and provides an important model to identify candidate genes. In this study, we report refined mapping of the mouse ichq locus and consideration of the candidate genes: calpain 1 (Capn1), phospholipase C beta 3 (Plcb3), and Rela and Ikka/Chuk that encode components of the nuclear factor-kappa B (NF-kappaB) pathway. Each are strong candidates because of epidermal expression and/or changes in expression in human HI. All candidates are linked to the ichq locus on mouse Chromosome 19, although Ikka is located more distally. Genetic mapping in mouse has narrowed the ichq critical region to 4 cM. Keratinocytes from skin of +/+, +/ichq and ichq/ichq mice were cultured; all genotypes had similar expression of epidermal differentiation markers. RT-PCR amplification and sequence analysis of each candidate gene did not reveal any mutations in the ichq mouse. Mutational screening of CAPN1 cDNA from different human HI cases revealed a R433P change, but analysis of 50 normal samples demonstrated that this was an apparent polymorphism. Sequence of RELA in five unrelated human HI cases was normal. The results provide compelling evidence that none of these genes are the primary defect in the ichq mouse and that CAPN1 and RELA are not mutated in the human disorder.
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Affiliation(s)
- Martine Dunnwald
- Department of Oral Biology, University of Washington, Seattle, WA., USA
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190
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Bosher JM, Hahn BS, Legouis R, Sookhareea S, Weimer RM, Gansmuller A, Chisholm AD, Rose AM, Bessereau JL, Labouesse M. The Caenorhabditis elegans vab-10 spectraplakin isoforms protect the epidermis against internal and external forces. J Cell Biol 2003; 161:757-68. [PMID: 12756232 PMCID: PMC2199363 DOI: 10.1083/jcb.200302151] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Morphogenesis of the Caenorhabditis elegans embryo is driven by actin microfilaments in the epidermis and by sarcomeres in body wall muscles. Both tissues are mechanically coupled, most likely through specialized attachment structures called fibrous organelles (FOs) that connect muscles to the cuticle across the epidermis. Here, we report the identification of new mutations in a gene known as vab-10, which lead to severe morphogenesis defects, and show that vab-10 corresponds to the C. elegans spectraplakin locus. Our analysis of vab-10 reveals novel insights into the role of this plakin subfamily. vab-10 generates isoforms related either to plectin (termed VAB-10A) or to microtubule actin cross-linking factor plakins (termed VAB-10B). Using specific antibodies and mutations, we show that VAB-10A and VAB-10B have distinct distributions and functions in the epidermis. Loss of VAB-10A impairs the integrity of FOs, leading to epidermal detachment from the cuticle and muscles, hence demonstrating that FOs are functionally and molecularly related to hemidesmosomes. We suggest that this isoform protects against forces external to the epidermis. In contrast, lack of VAB-10B leads to increased epidermal thickness during embryonic morphogenesis when epidermal cells change shape. We suggest that this isoform protects cells against tension that builds up within the epidermis.
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Affiliation(s)
- Julia M Bosher
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, BP10142, CU de Strasbourg, Illkirch Cedex F-67404, France
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191
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Fontao L, Favre B, Riou S, Geerts D, Jaunin F, Saurat JH, Green KJ, Sonnenberg A, Borradori L. Interaction of the bullous pemphigoid antigen 1 (BP230) and desmoplakin with intermediate filaments is mediated by distinct sequences within their COOH terminus. Mol Biol Cell 2003; 14:1978-92. [PMID: 12802069 PMCID: PMC165091 DOI: 10.1091/mbc.e02-08-0548] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2002] [Revised: 12/11/2002] [Accepted: 12/27/2002] [Indexed: 01/06/2023] Open
Abstract
The bullous pemphigoid antigen 1 (BP230) and desmoplakin (DP) are members of the plakin protein family of cytolinkers. Despite their homology, their COOH termini selectively bind distinct intermediate filaments (IFs). We studied sequences within their COOH termini required for their interaction with the epidermal keratins K5/K14, the simple epithelial keratins K8/K18, and type III IF vimentin by yeast three-hybrid, cell transfection, and overlay assays. The results indicate that BP230 interacts with K5/K14 but not with K8/K18 or vimentin via a region encompassing both the B and C subdomains and the COOH extremity, including a COOH-terminal eight-amino-acid stretch. In contrast, the C subdomain with the COOH-terminal extremity of DP interacts with K5/K14 and K8/K18, and its linker region is able to associate with K8/K18 and vimentin. Furthermore, the potential of DP to interact with IF proteins in yeast seems to be regulated by phosphorylation of Ser 2849 within its COOH terminus. Strikingly, BP230 and DP interacted with cytokeratins only when both type I and type II keratins were present. The head and tail domains of K5/K14 keratins were dispensable for their interaction with BP230 or DP. On the basis of our findings, we postulate that (1) the binding specificity of plakins for various IF proteins depends on their linker region between the highly homologous B and C subdomains and their COOH extremity and (2) the association of DP and BP230 with both epidermal and simple keratins is critically affected by the tertiary structure induced by heterodimerization and involves recognition sites located primarily in the rod domain of these keratins.
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Affiliation(s)
- Lionel Fontao
- Department of Dermatology, University Hospital, Geneva, Switzerland CH-1211
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192
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Xia CH, Roberts EA, Her LS, Liu X, Williams DS, Cleveland DW, Goldstein LSB. Abnormal neurofilament transport caused by targeted disruption of neuronal kinesin heavy chain KIF5A. J Cell Biol 2003; 161:55-66. [PMID: 12682084 PMCID: PMC2172877 DOI: 10.1083/jcb.200301026] [Citation(s) in RCA: 252] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
To test the hypothesis that fast anterograde molecular motor proteins power the slow axonal transport of neurofilaments (NFs), we used homologous recombination to generate mice lacking the neuronal-specific conventional kinesin heavy chain, KIF5A. Because null KIF5A mutants die immediately after birth, a synapsin-promoted Cre-recombinase transgene was used to direct inactivation of KIF5A in neurons postnatally. Three fourths of such mutant mice exhibited seizures and death at around 3 wk of age; the remaining animals survived to 3 mo or longer. In young mutant animals, fast axonal transport appeared to be intact, but NF-H, as well as NF-M and NF-L, accumulated in the cell bodies of peripheral sensory neurons accompanied by a reduction in sensory axon caliber. Older animals also developed age-dependent sensory neuron degeneration, an accumulation of NF subunits in cell bodies and a reduction in axons, loss of large caliber axons, and hind limb paralysis. These data support the hypothesis that a conventional kinesin plays a role in the microtubule-dependent slow axonal transport of at least one cargo, the NF proteins.
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Affiliation(s)
- Chun-Hong Xia
- Department of Cellular and Molecular Medicine, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093-0683, USA
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193
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Sawamura D, McMillan JR, Akiyama M, Shimizu H. Epidermolysis bullosa: directions for future research and new challenges for treatment. Arch Dermatol Res 2003; 295 Suppl 1:S34-42. [PMID: 12677431 DOI: 10.1007/s00403-002-0370-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Daisuke Sawamura
- Department of Dermatology, Hokkaido University Graduate School of Medicine, N15 West 7, Kita-ku, 060-8638 Sapporo, Japan.
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194
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Fernyhough P, Schmidt RE. Neurofilaments in diabetic neuropathy. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2003; 50:115-44. [PMID: 12198808 DOI: 10.1016/s0074-7742(02)50075-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This review discusses the role of abnormal neurofilament (NF) expression, processing, and structure as an etiological factor in diabetic neuropathy. Diabetic sensory and autonomic neuropathy in humans is associated with a spectrum of structural changes in peripheral nerve that includes axonal degeneration, paranodal demyelination, and loss of myelinated fibers-- the latter is probably the result of a dying-back of distal axons. NF filaments are composed of three subunit proteins, NFL, NFM, and NFH, and are major constituents of the axonal cylinder. It is clear that any abnormality in synthesis, delivery, or processing of these critical proteins could lead to severe impairments in axon structure and function. This article describes mechanisms of synthesis, phosphorylation, and delivery of NF and discusses how these processes may be abnormal in diabetics. The pathological alterations in the ganglion and preipheral nerve that occur in sensory and autonomic neuropath will be outlined and related to possible abnormal processing of NF. A major focus is the role or aberrant NF phosphorylation and its possible involvement in the imparied delivery of NF to the distal axon. Identification of stress-activated protein kinases (SAPKs) as NF kinases is discussed in detail and it is proposed that hyperglycemia-induced activation of SAPKs may be a primary etiological event in diabetic neuropathy.
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Affiliation(s)
- Paul Fernyhough
- School of Biological Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
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195
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Röper K, Gregory SL, Brown NH. The 'spectraplakins': cytoskeletal giants with characteristics of both spectrin and plakin families. J Cell Sci 2002; 115:4215-25. [PMID: 12376554 DOI: 10.1242/jcs.00157] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent studies have characterised a family of giant cytoskeletal crosslinkers encoded by the short stop gene in Drosophila and the dystonin/BPAG1 and MACF1 genes in mammals. We refer to the products of these genes as spectraplakins to highlight the fact that they share features with both the spectrin and plakin superfamilies. These genes produce a variety of large proteins, up to almost 9000 residues long, which can potentially extend 0.4 micro m across a cell. Spectraplakins can interact with all three elements of the cytoskeleton: actin, microtubules and intermediate filaments. The analysis of mutant phenotypes in BPAG1 in mouse and short stop in Drosophila demonstrates that spectraplakins have diverse roles. These include linking the plasma membrane and the cytoskeleton, linking together different elements of the cytoskeleton and organising membrane domains.
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Affiliation(s)
- Katja Röper
- Wellcome Trust/Cancer Research UK Institute and Dept of Anatomy, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QR, UK
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196
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Kazerounian S, Uitto J, Aho S. Unique role for the periplakin tail in intermediate filament association: specific binding to keratin 8 and vimentin. Exp Dermatol 2002; 11:428-38. [PMID: 12366696 DOI: 10.1034/j.1600-0625.2002.110506.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Plectin, desmoplakin, and the 230-kDa bullous pemphigoid antigen (BPAG1), members of the plakin family of proteins, are multifunctional cytolinkers, connecting the cytoskeletal structures to the cell adhesion complexes. Envoplakin and periplakin are components of the cornified envelope, but less is known about their role in tissues other than the stratified epithelium. Our tissue-wide survey utilizing RT-PCR revealed that periplakin, like plectin and desmoplakin, has a wide tissue distribution, but envoplakin expression is limited to certain tissues only, and BPAG1 is clearly specific for epidermal keratinocytes. Plectin, desmoplakin and BPAG1 are known to bind to the intermediate filaments through their C-terminal domains. The short C-terminal domain of periplakin is composed only of the linker domain, a region highly homologous between the plakin proteins. Here we demonstrate, through the use of yeast two-hybrid assay, a specific interaction of the periplakin linker domain with keratin 8 and vimentin. Co-expression of each plakin linker domain with keratin 8 revealed that periplakin and BPAG1 linkers co-localize with keratin signals in HaCaT cells, plectin and desmoplakin linkers were detected both in the nucleus and in cytoplasm together with the overexpressed keratin 8, while envoplakin linker localized independently into the nucleus. These results suggest that, in spite of its high homology and structural similarity with envoplakin, periplakin is functionally closer to the well-characterized plakin proteins plectin and desmoplakin, and thus may function tissue-wide as a scaffolding protein in intermediate filament assembly.
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Affiliation(s)
- Shideh Kazerounian
- Department of Dermatology and Cutaneous Biology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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197
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Rao MV, Garcia ML, Miyazaki Y, Gotow T, Yuan A, Mattina S, Ward CM, Calcutt NA, Uchiyama Y, Nixon RA, Cleveland DW. Gene replacement in mice reveals that the heavily phosphorylated tail of neurofilament heavy subunit does not affect axonal caliber or the transit of cargoes in slow axonal transport. J Cell Biol 2002; 158:681-93. [PMID: 12186852 PMCID: PMC2174004 DOI: 10.1083/jcb.200202037] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2002] [Revised: 06/24/2002] [Accepted: 06/25/2002] [Indexed: 11/22/2022] Open
Abstract
The COOH-terminal tail of mammalian neurofilament heavy subunit (NF-H), the largest neurofilament subunit, contains 44-51 lysine-serine-proline repeats that are nearly stoichiometrically phosphorylated after assembly into neurofilaments in axons. Phosphorylation of these repeats has been implicated in promotion of radial growth of axons, control of nearest neighbor distances between neurofilaments or from neurofilaments to other structural components in axons, and as a determinant of slow axonal transport. These roles have now been tested through analysis of mice in which the NF-H gene was replaced by one deleted in the NF-H tail. Loss of the NF-H tail and all of its phosphorylation sites does not affect the number of neurofilaments, alter the ratios of the three neurofilament subunits, or affect the number of microtubules in axons. Additionally, it does not reduce interfilament spacing of most neurofilaments, the speed of action potential propagation, or mature cross-sectional areas of large motor or sensory axons, although its absence slows the speed of acquisition of normal diameters. Most surprisingly, at least in optic nerve axons, loss of the NF-H tail does not affect the rate of transport of neurofilament subunits.
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Affiliation(s)
- Mala V Rao
- Nathan Kline Institute, New York University School of Medicine, Orangeburg, NY 10962, USA.
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198
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Boudreau-Larivière C, Kothary R. Differentiation potential of primary myogenic cells derived from skeletal muscle of dystonia musculorum mice. Differentiation 2002; 70:247-56. [PMID: 12190986 DOI: 10.1046/j.1432-0436.2002.700603.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The dystonia musculorum (dt) mouse has a mutation in the gene encoding the cytoskeletal crosslinker protein bullous pemphigoid antigen 1 (Bpag1). These mice have perturbations in the cytoarchitecture of skeletal muscle. Bpag1 has been hypothesized to be involved in the maintenance rather than the establishment of the muscle cell architecture given that cytoskeletal disruptions are observed in the muscle tissue of post-natal dt mice. Not known is whether Bpag1-deficiency affects the proliferative and differentiation potential of myogenic cells. In the present investigation, we show that the growth rate of cultured primary myogenic cells derived from dt mice, as assessed by BrdU incorporation, is similar to that of myogenic cells derived from wild-type littermates. The myogenic differentiation potential of dt versus wild-type cells was monitored by examining the expression of myosin heavy chain by immunofluorescence, and by analyzing the expression profiles of myogenic regulatory factors and myogenic differentiation markers by RT-PCR. In all instances, both dt and wild-type myogenic cells displayed a similar differentiation profile. Furthermore, the absence of any observable differences in the proliferation and differentiation rates of dt and wild-type cells was not due to an overexpression of plectin, another crosslinker protein, in dt cells. Together, these findings demonstrate that the early phases of myogenic differentiation occur independently of Bpag1.
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199
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Larivière RC, Nguyen MD, Ribeiro-da-Silva A, Julien JP. Reduced number of unmyelinated sensory axons in peripherin null mice. J Neurochem 2002; 81:525-32. [PMID: 12065660 DOI: 10.1046/j.1471-4159.2002.00853.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Peripherin is a type III intermediate filament (IF) abundantly expressed in developing neurons, but in the adult, it is primarily found in neurons extending to the peripheral nervous system. It has been suggested that peripherin may play a role in axonal elongation and/or cytoskeletal stabilization during development and regeneration. To further clarify the function of peripherin, we generated and characterized mice with a targeted disruption of the peripherin gene. The peripherin null mice were viable, reproduced normally and did not exhibit overt phenotypes. Microscopic analysis revealed no gross morphological defects in the ventral and dorsal roots, spinal cord, retina and gut, but protein analyses showed increased levels of the type IV IF alpha-internexin in ventral roots of peripherin null mice. Whereas the number and caliber of myelinated motor and sensory axons in the L5 roots remained unchanged in peripherin knockout mice, there was a substantial reduction ( approximately 34%) in the number of L5 unmyelinated sensory fibers that correlated with a decreased binding of the lectin IB4. These results demonstrate a requirement of peripherin for the proper development of a subset of sensory neurons.
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Affiliation(s)
- R C Larivière
- Department of Neurology and Neurosurgery, McGill University, Montreal, Canada
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200
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Hertl M, Schuler G. [Bullous autoimmune dermatoses. 2: Pathogenesis]. DER HAUTARZT 2002; 53:277-85; quiz 285, 287. [PMID: 12053698 DOI: 10.1007/s00105-002-0356-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M Hertl
- Dermatologische Klinik mit Poliklinik, Universität Erlangen, Hartmannstrasse 14, 91052 Erlangen.
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