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Tanikawa C, Zhang YZ, Yamamoto R, Tsuda Y, Tanaka M, Funauchi Y, Mori J, Imoto S, Yamaguchi R, Nakamura Y, Miyano S, Nakagawa H, Matsuda K. The Transcriptional Landscape of p53 Signalling Pathway. EBioMedicine 2017; 20:109-119. [PMID: 28558959 PMCID: PMC5478243 DOI: 10.1016/j.ebiom.2017.05.017] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 05/09/2017] [Accepted: 05/10/2017] [Indexed: 02/07/2023] Open
Abstract
Although recent cancer genomics studies have identified a large number of genes that were mutated in human cancers, p53 remains as the most frequently mutated gene. To further elucidate the p53-signalling network, we performed transcriptome analysis on 24 tissues in p53+/+ or p53−/− mice after whole-body X-ray irradiation. Here we found transactivation of a total of 3551 genes in one or more of the 24 tissues only in p53+/+ mice, while 2576 genes were downregulated. p53 mRNA expression level in each tissue was significantly associated with the number of genes upregulated by irradiation. Annotation using TCGA (The Cancer Genome Atlas) database revealed that p53 negatively regulated mRNA expression of several cancer therapeutic targets or pathways such as BTK, SYK, and CTLA4 in breast cancer tissues. In addition, stomach exhibited the induction of Krt6, Krt16, and Krt17 as well as loricrin, an epidermal differentiation marker, after the X-ray irradiation only in p53+/+ mice, implying a mechanism to protect damaged tissues by rapid induction of differentiation. Our comprehensive transcriptome analysis elucidated tissue specific roles of p53 and its signalling networks in DNA-damage response that will enhance our understanding of cancer biology. Transcriptome analysis across 24 mouse tissues identified a total of 3551 p53-induced genes and 2576 p53-repressed genes. p53 mRNA in each tissue was associated with the numbers of p53-induced/repressed genes. p53 would protect gastric epithelial cells from X-ray irradiation through the induction of differentiation and keratinization
p53 is the most frequently mutated tumor-suppressor that functions as a transcription factor. Transcriptome analysis of 280 samples from 24 tissues identified 3551 p53-induced and 2576 p53-repressed genes. p53 negatively regulated several cancer therapeutic targets, BTK, SYK, and CTLA4 in breast cancer tissues. Majority of X-ray responsive genes were regulated by p53 and p53 mRNA expression in each tissue was associated with the numbers of p53-induced and repressed genes, demonstrating its crucial roles in damage response. The whole-body transcriptome analysis revealed that p53 would protect gastric epithelial cells from X-ray irradiation through the induction of differentiation and keratinization.
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Affiliation(s)
- Chizu Tanikawa
- Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Yao-Zhong Zhang
- Laboratory of DNA information Analysis, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Ryuta Yamamoto
- Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Yusuke Tsuda
- Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Masami Tanaka
- Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Yuki Funauchi
- Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Jinichi Mori
- Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan; Laboratory of Clinical Genome Sequence, Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Japan
| | - Seiya Imoto
- Laboratory of DNA information Analysis, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Rui Yamaguchi
- Laboratory of DNA information Analysis, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Yusuke Nakamura
- Department of Medicine, Center for Personalized Therapeutics, The University of Chicago, USA; Department of Surgery, Center for Personalized Therapeutics, The University of Chicago, USA
| | - Satoru Miyano
- Laboratory of DNA information Analysis, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan
| | - Hidewaki Nakagawa
- Laboratory for Genome Sequencing Analysis, RIKEN Center for Integrative Medical Sciences, Tokyo, Japan
| | - Koichi Matsuda
- Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan; Laboratory of Clinical Genome Sequence, Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Japan.
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Alvarado DM, Coulombe PA. Directed expression of a chimeric type II keratin partially rescues keratin 5-null mice. J Biol Chem 2014; 289:19435-47. [PMID: 24867950 DOI: 10.1074/jbc.m114.553867] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The crucial role of structural support fulfilled by keratin intermediate filaments (IFs) in surface epithelia likely requires that they be organized into cross-linked networks. For IFs comprised of keratins 5 and 14 (K5 and K14), which occur in basal keratinocytes of the epidermis, formation of cross-linked bundles is, in part, self-driven through cis-acting determinants. Here, we targeted the expression of a bundling-competent KRT5/KRT8 chimeric cDNA (KRT8bc) or bundling-deficient wild type KRT8 as a control to the epidermal basal layer of Krt5-null mice to assess the functional importance of keratin IF self-organization in vivo. Such targeted expression of K8bc rescued Krt5-null mice with a 47% frequency, whereas K8 completely failed to do so. This outcome correlated with lower than expected levels of K8bc and especially K8 mRNA and protein in the epidermis of E18.5 replacement embryos. Ex vivo culture of embryonic skin keratinocytes confirmed the ability of K8bc to form IFs in the absence of K5. Additionally, electron microscopy analysis of E18.5 embryonic skin revealed that the striking defects observed in keratin IF bundling, cytoarchitecture, and mitochondria are partially restored by K8bc expression. As young adults, viable KRT8bc replacement mice develop alopecia and chronic skin lesions, indicating that the skin epithelia are not completely normal. These findings are consistent with a contribution of self-mediated organization of keratin IFs to structural support and cytoarchitecture in basal layer keratinocytes of the epidermis and underscore the importance of context-dependent regulation for keratin genes and proteins in vivo.
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Affiliation(s)
- David M Alvarado
- From the Training Program in Cellular and Molecular Medicine and Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205
| | - Pierre A Coulombe
- From the Training Program in Cellular and Molecular Medicine and Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205Departments of Biological Chemistry and Dermatology, School of Medicine and
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Affiliation(s)
- Rebecca L Haines
- Epithelial Biology Group, Institute of Medical Biology, Immunos, Singapore
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Coulombe PA, Lee CH. Defining keratin protein function in skin epithelia: epidermolysis bullosa simplex and its aftermath. J Invest Dermatol 2012; 132:763-75. [PMID: 22277943 PMCID: PMC3279600 DOI: 10.1038/jid.2011.450] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Epidermolysis bullosa simplex (EBS) is a rare genetic condition typified by superficial bullous lesions following incident frictional trauma to the skin. Most cases of EBS are due to dominantly acting mutations in keratin 14 (K14) or K5, the type I and II intermediate filament (IF) proteins that copolymerize to form a pancytoplasmic network of 10 nm filaments in basal keratinocytes of epidermis and related epithelia. Defects in K5-K14 filament network architecture cause basal keratinocytes to become fragile, and account for their rupture upon exposure to mechanical trauma. The discovery of the etiology and pathophysiology of EBS was intimately linked to the quest for an understanding of the properties and function of keratin filaments in skin epithelia. Since then, continued cross-fertilization between basic science efforts and clinical endeavors has highlighted several additional functional roles for keratin proteins in the skin, suggested new avenues for effective therapies for keratin-based diseases, and expanded our understanding of the remarkable properties of the skin as an organ system.
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Affiliation(s)
- Pierre A Coulombe
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA.
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Strnad P, Usachov V, Debes C, Gräter F, Parry DAD, Omary MB. Unique amino acid signatures that are evolutionarily conserved distinguish simple-type, epidermal and hair keratins. J Cell Sci 2012; 124:4221-32. [PMID: 22215855 DOI: 10.1242/jcs.089516] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Keratins (Ks) consist of central α-helical rod domains that are flanked by non-α-helical head and tail domains. The cellular abundance of keratins, coupled with their selective cell expression patterns, suggests that they diversified to fulfill tissue-specific functions although the primary structure differences between them have not been comprehensively compared. We analyzed keratin sequences from many species: K1, K2, K5, K9, K10, K14 were studied as representatives of epidermal keratins, and compared with K7, K8, K18, K19, K20 and K31, K35, K81, K85, K86, which represent simple-type (single-layered or glandular) epithelial and hair keratins, respectively. We show that keratin domains have striking differences in their amino acids. There are many cysteines in hair keratins but only a small number in epidermal keratins and rare or none in simple-type keratins. The heads and/or tails of epidermal keratins are glycine and phenylalanine rich but alanine poor, whereas parallel domains of hair keratins are abundant in prolines, and those of simple-type epithelial keratins are enriched in acidic and/or basic residues. The observed differences between simple-type, epidermal and hair keratins are highly conserved throughout evolution. Cysteines and histidines, which are infrequent keratin amino acids, are involved in de novo mutations that are markedly overrepresented in keratins. Hence, keratins have evolutionarily conserved and domain-selectively enriched amino acids including glycine and phenylalanine (epidermal), cysteine and proline (hair), and basic and acidic (simple-type epithelial), which reflect unique functions related to structural flexibility, rigidity and solubility, respectively. Our findings also support the importance of human keratin 'mutation hotspot' residues and their wild-type counterparts.
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Affiliation(s)
- Pavel Strnad
- Department of Internal Medicine I, Center for Internal Medicine, University Medical Center Ulm, Albert-Einstein-Allee 23, D-89081 Ulm, Germany.
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Wagner M, Hintner H, Bauer JW, Onder K. Gene expression analysis of an epidermolysis bullosa simplex Dowling-Meara cell line by subtractive hybridization: recapitulation of cellular differentiation, migration and wound healing. Exp Dermatol 2011; 21:111-7. [DOI: 10.1111/j.1600-0625.2011.01420.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Morphological evaluation of tongue mucosa in burning mouth syndrome. Arch Oral Biol 2011; 57:94-101. [PMID: 21824605 DOI: 10.1016/j.archoralbio.2011.07.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 07/14/2011] [Accepted: 07/18/2011] [Indexed: 11/23/2022]
Abstract
OBJECTIVE The aim of the present study was to perform a morphological evaluation by immunofluorescence of biomarkers of keratinocyte intercellular adhesion, and of differentiation in the tongue mucosa of burning mouth syndrome patients (BMS), compared with a control group. DESIGN A prospective blinded evaluation of tongue mucosal specimens processed for light microscopy was performed. Intercellular adhesion was evaluated by investigating the expression of desmoglein 1, desmoglein 3, and of occludin. Keratin 10 and keratin 14 (markers of epithelial differentiation) were also evaluated, as keratin 16 (marker for activated keratinocytes after epithelial injury). Apoptotic cascade was investigated by p53 and activated caspase-3 expression. The basal membrane integrity was analysed through laminin immunoreactivity. RESULTS In both groups, a preserved three-dimensional architecture of the tongue was observed. Desmoglein 1 and desmoglein 3 epithelial distributions were similar in the desmosomes of patients and control subjects. Again, keratin 10 immunoreactivity and distribution pattern of keratin 14 in the epithelial compartment was similar in both groups. In control samples, keratin 16 immunoreactivity was scant throughout the epithelium with a punctuate and scattered cytoplasmic labelling. In contrast, in all BMS patients keratinocyte cytoplasm was homogeneously labelled for keratin 16, with a more intense staining than controls. Furthermore, keratin 16 staining progressively decreased proceeding towards the most superficial epithelial layers. CONCLUSIONS The results of this study are consistent with and support the clinically normal features of oral mucosa in BMS, and suggest that keratin 16 may be involved in the cell mechanisms underlying the syndrome occurrence.
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Kerns M, DePianto D, Yamamoto M, Coulombe PA. Differential modulation of keratin expression by sulforaphane occurs via Nrf2-dependent and -independent pathways in skin epithelia. Mol Biol Cell 2010; 21:4068-75. [PMID: 20926689 PMCID: PMC2993737 DOI: 10.1091/mbc.e10-02-0153] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Treatment with the natural chemical sulforaphane (SF) ameliorates skin blistering in keratin 14 (K14)-deficient mice, correlating with the induction of K16 and K17 in the basal layer of epidermis (Kerns et al., PNAS 104:14460, 2007). Here we address the basis for the SF-mediated K16 and K17 induction in mouse epidermis in vivo. As expected, induction of K16 partly depends on the transcription factor Nrf2, which is activated by SF exposure. Strikingly, K17 induction occurs independently of Nrf2 activity and parallels the decrease in glutathione occurring shortly after epidermal exposure to SF. Pharmacological manipulation of glutathione levels in mouse epidermis in vivo alters K17 and K16 expression in the expected manner. We present findings suggesting that select MAP kinases participate in mediating the Nrf2- and glutathione-dependent alterations in K16 and K17 levels in SF-treated epidermis. These findings advance our understanding of the effect of SF on gene expression in epidermis, point to a role for glutathione in mediating some of these effects, and establish that SF induces the expression of two contiguous and highly related genes, K16 and K17, via distinct mechanisms.
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Affiliation(s)
- Michelle Kerns
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
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Trost A, Costa I, Jakab M, Ritter M, Haim M, Hintner H, Bauer JW, Önder K. K16 is a further new candidate for homotypic intermediate filament protein interactions. Exp Dermatol 2009; 19:e241-50. [DOI: 10.1111/j.1600-0625.2010.01071.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Lee CH, Coulombe PA. Self-organization of keratin intermediate filaments into cross-linked networks. ACTA ACUST UNITED AC 2009; 186:409-21. [PMID: 19651890 PMCID: PMC2728393 DOI: 10.1083/jcb.200810196] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Keratins, the largest subgroup of intermediate filament (IF) proteins, form a network of 10-nm filaments built from type I/II heterodimers in epithelial cells. A major function of keratin IFs is to protect epithelial cells from mechanical stress. Like filamentous actin, keratin IFs must be cross-linked in vitro to achieve the high level of mechanical resilience characteristic of live cells. Keratins 5 and 14 (K5 and K14), the main pairing occurring in the basal progenitor layer of epidermis and related epithelia, can readily self-organize into large filament bundles in vitro and in vivo. Here, we show that filament self-organization is mediated by multivalent interactions involving distinct regions in K5 and K14 proteins. Self-organization is determined independently of polymerization into 10-nm filaments, but involves specific type I–type II keratin complementarity. We propose that self-organization is a key determinant of the structural support function of keratin IFs in vivo.
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Affiliation(s)
- Chang-Hun Lee
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
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11
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Coulombe PA, Kerns ML, Fuchs E. Epidermolysis bullosa simplex: a paradigm for disorders of tissue fragility. J Clin Invest 2009; 119:1784-93. [PMID: 19587453 PMCID: PMC2701872 DOI: 10.1172/jci38177] [Citation(s) in RCA: 143] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Epidermolysis bullosa (EB) simplex is a rare genetic condition typified by superficial bullous lesions that result from frictional trauma to the skin. Most cases are due to dominantly acting mutations in either keratin 14 (K14) or K5, the type I and II intermediate filament (IF) proteins tasked with forming a pancytoplasmic network of 10-nm filaments in basal keratinocytes of the epidermis and in other stratified epithelia. Defects in K5/K14 filament network architecture cause basal keratinocytes to become fragile and account for their trauma-induced rupture. Here we review how laboratory investigations centered on keratin biology have deepened our understanding of the etiology and pathophysiology of EB simplex and revealed novel avenues for its therapy.
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Affiliation(s)
- Pierre A Coulombe
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA.
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Henno A, Blacher S, Lambert C, Colige A, Seidel L, Noël A, Lapière C, de la Brassinne M, Nusgens B. Altered expression of angiogenesis and lymphangiogenesis markers in the uninvolved skin of plaque-type psoriasis. Br J Dermatol 2009; 160:581-90. [DOI: 10.1111/j.1365-2133.2008.08889.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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13
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Hachiya A, Sriwiriyanont P, Fujimura T, Ohuchi A, Kitahara T, Takema Y, Kitzmiller WJ, Visscher MO, Tsuboi R, Boissy RE. Mechanistic effects of long-term ultraviolet B irradiation induce epidermal and dermal changes in human skin xenografts. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 174:401-13. [PMID: 19147832 DOI: 10.2353/ajpath.2009.070500] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
UVB irradiation has been reported to induce photoaging and suppress systemic immune function that could lead to photocarcinogenesis. However, because of the paucity of an UVB-induced photodamaged skin model, precise and temporal mechanism(s) underlying the deleterious effects of long-term UVB exposure on human skin have yet to be delineated. In this study, we established a model using human skin xenografted onto severe combined immunodeficient mice, which were subsequently challenged by repeated UVB irradiation for 6 weeks. Three-dimensional optical image analysis of skin replicas and noninvasive biophysical measurements illustrated a significant increase in skin surface roughness, similar to premature photoaging, and a significant loss of skin elasticity after long-term UVB exposure. Resembling authentically aged skin, UVB-exposed samples exhibited significant increases in epithelial keratins (K6, K16, K17), elastins, and matrix metalloproteinases (MMP-1, MMP-9, MMP-12) as well as degradation of collagens (I, IV, VII). The UVB-induced deterioration of fibrous keratin intermediate filaments was also observed in the stratum corneum. Additionally, similarities in gene expression patterns between our model and chronologically aged skin substantiated the plausible relationship between photodamage and chronological age. Furthermore, severe skin photodamage was observed when neutralizing antibodies against TIMP-1, an endogenous inhibitor of MMPs, were administered during the UVB exposure regimen. Taken together, these findings suggest that our skin xenograft model recapitulates premature photoaged skin and provides a comprehensive tool with which to assess the deleterious effects of UVB irradiation.
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Oender K, Trost A, Lanschuetzer C, Laimer M, Emberger M, Breitenbach M, Richter K, Hintner H, Bauer JW. Cytokeratin-related loss of cellular integrity is not a major driving force of human intrinsic skin aging. Mech Ageing Dev 2008; 129:563-71. [PMID: 18582489 DOI: 10.1016/j.mad.2008.05.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2007] [Revised: 05/13/2008] [Accepted: 05/16/2008] [Indexed: 12/15/2022]
Abstract
The contribution of extracellular matrix components to intrinsic skin aging has been investigated thoroughly, however, there is little information as to the role of the cytoskeletal proteins in this process. Therefore, we compared the expression of the constituents of the cytoskeleton, keratins 1-23 (K1-K23) as well as junction-plakoglobin (JUP), alpha-tubulin (TUBA), and beta-actin (ACTB) in human foreskins of both young (mean 6.4 years) and aged (mean 54.3 years) individuals. By applying RNA expression analysis to intrinsically aged human skin, we demonstrated that the mRNA levels of the genes for K1, K3, K4, K9, K13, K15, K18, K19 and K20 are downregulated in aged skin, K5 and K14 are unchanged, and K2, K16 and K17 are upregulated in aged skin. The mRNA data were confirmed on the protein level. This diverse picture is in contrast to other cytoskeletal proteins including components of the desmosome (JUP), microtubuli (TUBA) and microfilaments (ACTB) - often regarded as house-keeping genes - that were all reduced in aged skin. These cytoskeletal features of intrinsic aging highlight the importance of the cellular compartment in this process and demonstrate that special attention has to be given to RNA as well as protein normalization in aging studies.
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Affiliation(s)
- Kamil Oender
- Department of Dermatology, Muellner Hauptstrasse 48, A-5020 Salzburg, Austria
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Usui ML, Mansbridge JN, Carter WG, Fujita M, Olerud JE. Keratinocyte migration, proliferation, and differentiation in chronic ulcers from patients with diabetes and normal wounds. J Histochem Cytochem 2008; 56:687-96. [PMID: 18413645 DOI: 10.1369/jhc.2008.951194] [Citation(s) in RCA: 168] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Epithelialization of normal acute wounds occurs by an orderly series of events whereby keratinocytes migrate, proliferate, and differentiate to restore barrier function. The keratinocytes in the epidermis of chronic ulcers fail to execute this series of events. To better understand the epithelial dynamics of chronic ulcers, we used immunohistochemistry to evaluate proliferation, differentiation, adhesion, and migration in keratinocytes along the margin of chronic ulcers from patients with diabetes mellitus. We compared these features with keratinocytes from the migrating epithelial tongues of acute incisional and excisional wounds from normal volunteers. Keratinocytes at the chronic ulcer edge are highly proliferative (Ki67 proliferation marker), have an activated phenotype (K16), do not stain for keratins involved in epidermal differentiation (K10 and K2), and show a reduced expression of LM-3A32 (uncleaved, precursor of the alpha3 chain of laminin 5), a key molecule present on migrating epithelium. In contrast, keratinocytes in normal acute wound migrating epithelium do not express the proliferation marker Ki67 but do express K10, K2, and LM-3A32. A better understanding of molecular mechanisms involved in keratinocyte migration may lead to molecular targets for therapies for impaired wound healing.
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Affiliation(s)
- Marcia L Usui
- Department of Medicine (Dermatology), University of Washington, 1959 NE Pacific Street, Box 356524, Seattle, WA 98195-6524, USA.
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Guttormsen J, Koster MI, Stevens JR, Roop DR, Williams T, Winger QA. Disruption of epidermal specific gene expression and delayed skin development in AP-2 gamma mutant mice. Dev Biol 2008; 317:187-95. [PMID: 18353300 DOI: 10.1016/j.ydbio.2008.02.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Revised: 02/07/2008] [Accepted: 02/08/2008] [Indexed: 12/16/2022]
Abstract
Summary Sentence: Conditional ablation of AP-2 gamma results in a delay in skin development and abnormal expression of p63, K14, K1, filaggrin, repetin and secreted Ly6/Plaur domain containing 1, key genes required for epidermal development and differentiation. The development of the epidermis, a stratified squamous epithelium, is dependent on the regulated differentiation of keratinocytes. Differentiation begins with the initiation of stratification, a process tightly controlled through proper gene expression. AP-2 gamma is expressed in skin and previous research suggested a pathway where p63 gene induction results in increased expression of AP-2 gamma, which in turn is responsible for induction of K14. This study uses a conditional gene ablation model to further explore the role of AP-2 gamma in skin development. Mice deficient for AP-2 gamma exhibited delayed expression of p63, K14, and K1, key genes required for development and differentiation of the epidermis. In addition, microarray analysis of E16.5 skin revealed delayed expression of additional late epidermal differentiation genes: filaggrin, repetin and secreted Ly6/Plaur domain containing 1, in mutant mice. The genetic delay in skin development was further confirmed by a functional delay in the formation of an epidermal barrier. These results document an important role for AP-2 gamma in skin development, and reveal the existence of regulatory factors that can compensate for AP-2 gamma in its absence.
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Affiliation(s)
- Jillian Guttormsen
- Department of Animal, Dairy and Veterinary Sciences, Utah State University, Logan, UT, USA
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Kerns ML, DePianto D, Dinkova-Kostova AT, Talalay P, Coulombe PA. Reprogramming of keratin biosynthesis by sulforaphane restores skin integrity in epidermolysis bullosa simplex. Proc Natl Acad Sci U S A 2007; 104:14460-5. [PMID: 17724334 PMCID: PMC1964870 DOI: 10.1073/pnas.0706486104] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Epidermolysis bullosa simplex (EBS) is a rare inherited condition in which the epidermis loses its integrity after mechanical trauma. EBS is typified by the dysfunction of intermediate filaments in basal keratinocytes of epidermis. Most cases of EBS are due to mutations in the keratin 5 or 14 gene (K5 and K14), whose products copolymerize to form intermediate filaments in basal keratinocytes. Available treatments for this disorder are only palliative. Here we exploit functional redundancy within the keratin gene family as the basis for therapy. We show that genetic activation of Gli2 or treatment with a pharmacological activator of Nrf2, two transcription factors eliciting distinct transcriptional programs, alleviates the blistering caused by a K14 deficiency in an EBS mouse model, correlating with K17 induction in basal epidermal keratinocytes. Nrf2 induction is brought about by treatment with sulforaphane, a natural product. Sulforaphane thus represents an attractive option for the prevention of skin blistering associated with K14 mutations in EBS.
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Affiliation(s)
| | | | | | - Paul Talalay
- Pharmacology and Molecular Sciences, and
- To whom correspondence may be addressed. E-mail: or
| | - Pierre A. Coulombe
- Departments of *Biological Chemistry
- Dermatology, 725 North Wolfe Street, The Johns Hopkins University School of Medicine, Baltimore, MD 21205
- To whom correspondence may be addressed. E-mail: or
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Gu LH, Coulombe PA. Keratin expression provides novel insight into the morphogenesis and function of the companion layer in hair follicles. J Invest Dermatol 2006; 127:1061-73. [PMID: 17170733 DOI: 10.1038/sj.jid.5700673] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hair follicles cycle between stages of growth (anagen) and metabolic quiescence (telogen) throughout life. In mature follicles, transition from telogen back into anagen involves the activation, proliferation, and differentiation of epithelial stem cells located in the bulge, a specialization of the outer root sheath. Recent studies identified keratin 6a (K6a) transcripts as enriched in bulge epithelial stem cells in mouse skin. We used messenger RNA probes, antibodies, a LacZ reporter mouse model, and whole-mount staining assays to investigate the regulation of mK6a during mouse postnatal hair cycling, and compare it to mK75, a companion layer (Cl) marker. We find that mK75 regulation parallels that of inner root sheath (IRS) markers, with expression onset at anagen IIIa above the new hair bulb and subsequent spreading towards the bulge. Although also occurring in the Cl, mK6a expression begins at anagen IIIb in differentiating cells located proximal to the bulge, and subsequently spreads towards the hair bulb. mK6a and mK75 thus exhibit temporally distinct, and spatially opposed, expression patterns in the Cl during postnatal anagen. These findings provide novel insight into the morphogenesis and properties of the Cl, and raise the distinct possibility that it is an integral part of the IRS compartment.
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Affiliation(s)
- Li-Hong Gu
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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19
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Fromes Y, Liu JM, Kovacevic M, Bignon J, Wdzieczak-Bakala J. The tetrapeptide acetyl-serine-aspartyl-lysine-proline improves skin flap survival and accelerates wound healing. Wound Repair Regen 2006; 14:306-12. [PMID: 16808809 DOI: 10.1111/j.1743-6109.2006.00125.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The tetrapeptide acetyl-serine-aspartyl-lysine-proline (AcSDKP) has recently been recognized as a potent angiogenic factor. Given the importance of vascular blood supply in the process of tissue repair we have investigated the ability of AcSDKP to contribute to the repair of cutaneous injuries by using dorsal and abdominal skin flap models. Postoperative subdermal AcSDKP injections (5 microg/kg/injection twice a day for 3 days following flap elevation) prevented marginally perfused areas from undergoing necrosis. Mean skin survival area of abdominal and dorsal flaps ranged, respectively, from 50.9+/-19.3 and 53.4+/-4.2% in the control groups to 66.4+/-7.5 and 74.7+/-6.6% in AcSDKP-treated groups. Furthermore, in an ex vivo assay, AcSDKP applied locally to skin explants at doses from 10(-8) to 10(-5) M improved survival of the explanted skin exposed to UVB irradiation at 10 J/cm2. Increased reepithelialization, as well as higher levels of expression of basal keratin 14 and increased expression of fibronectin was observed after topical application of AcSDKP. These data provide experimental evidence that AcSDKP can improve the viability of ischemic skin flaps in the rat by promoting angiogenesis. Moreover, it enhances wound healing of injured avascular skin explants. Thus, these findings identify AcSDKP as a new tissue-repair agent and suggest its potential clinical use for the management of skin wounds.
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Affiliation(s)
- Yves Fromes
- Institut de Myologie, INSERM U582, Paris, France.
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20
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Lu H, Zimek A, Chen J, Hesse M, Büssow H, Weber K, Magin TM. Keratin 5 knockout mice reveal plasticity of keratin expression in the corneal epithelium. Eur J Cell Biol 2006; 85:803-11. [PMID: 16759736 DOI: 10.1016/j.ejcb.2006.04.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2006] [Revised: 04/03/2006] [Accepted: 04/07/2006] [Indexed: 01/12/2023] Open
Abstract
We have recently demonstrated that the keratin K3 gene, which is active in the suprabasal human corneal epithelium, is missing in the genome of the mouse. We show that a normal K3 gene exists in a wide variety of mammals while in rodents the gene is converted to a pseudogene with a very strong sequence drift. The availability of K5-/- mice provides a unique opportunity to investigate type-specific keratin function during corneal differentiation in the absence of both K5 and K3. Here, we report that the deletion of K5, which in wild-type mice forms a cytoskeleton with K12, does neither cause keratin aggregation nor cytolysis in the cornea. This is due to the induction of K4 in corneal epithelial cells, normally restricted to corneal stem stem cells residing in the limbus. Using a combination of antibodies and RT-PCR, we identified additional keratins expressed in the mouse cornea including K23 which was previously thought to be specific for pancreatic carcinomas. This reflects an unexpected complexity of keratin expression in the cornea. Our data suggest that in the absence of mechanical stress, corneal differentiation does not depend on distinct keratin pairs, supporting a concept of functional redundancy, at least for certain keratins.
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Affiliation(s)
- Hong Lu
- Institut für Physiologische Chemie, Abteilung für Zellbiochemie, Bonner Forum Biomedizin and LIMES, Rheinische Friedrich-Wilhelms-Universität, Nussallee 11, D-53115 Bonn, Germany
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21
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Alibardi L. Structural and Immunocytochemical Characterization of Keratinization in Vertebrate Epidermis and Epidermal Derivatives. INTERNATIONAL REVIEW OF CYTOLOGY 2006; 253:177-259. [PMID: 17098057 DOI: 10.1016/s0074-7696(06)53005-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This review presents comparative aspects of epidermal keratinization in vertebrates, with emphasis on the evolution of the stratum corneum in land vertebrates. The epidermis of fish does not contain proteins connected with interkeratin matrix and corneous cell envelope formation. Mucus-like material glues loose keratin filaments. In amphibians a cell corneous envelope forms but matrix proteins, aside from mucus/glycoproteins, are scarce or absent. In reptiles, birds, and mammals specific proteins associated with keratin become relevant for the production of a resistant corneous layer. In reptiles some matrix, histidine-rich and sulfur-rich corneous cell envelope proteins are produced in the soft epidermis. In avian soft epidermis low levels of matrix and cornified proteins are present while lipids become abundant. In mammalian keratinocytes, interkeratin proteins, cornified cell envelope proteins, and transglutaminase are present. Topographically localized areas of dermal-epidermal interactions in amniote skin determine the formation of skin derivatives such as scales, feathers, and hairs. New types of keratin and associated proteins are produced in these derivatives. In reptiles and birds beta-keratins form the hard corneous material of scales, claws, beaks, and feathers. In mammals, small sulfur-rich and glycine-tyrosine-rich proteins form the corneous material of hairs, horns, hooves, and claws. Molecular studies on reptilian beta-keratins show they are glycine-rich proteins. They have C- and N-terminal amino acid regions homologous to those of mammalian proteins and a central core with homology to avian scale/feather keratins. These findings suggest that ancient reptiles already possessed some common genes that later diversified to produce some keratin-associated protein in extant reptiles and birds, and others in mammals. The evolution of these small proteins represents the more recent variation of the process of cornification in vertebrates.
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Affiliation(s)
- Lorenzo Alibardi
- Department of Experimental and Evolutionary Biology, University of Bologna, 40126 Bologna, Italy
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22
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Abstract
Hair and nails are often stated to have much in common in relation to their origin, anatomical structures, and common involvement in many diseases. Hair and nails are predominantly epithelial structures derived from primitive epidermis and made up of keratinous fibrils embedded in a sulfur-rich matrix. It was first noted early in the 20th century that the nail unit was comparable in several respects to a hair follicle sectioned longitudinally and laid on on its side. The epithelial components of hair follicle and nail apparatus are differentiated epidermal structures that may be involved jointly in several ways as congenital and hereditary anomalies and acquired conditions such as alopecia areata, lichen planus, iatrogenic causes, and fungal infection. Multielemental characterization of human hair and nails shows that even after sample washing, many elements are enriched in the surface of the nails.
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Affiliation(s)
- Robert Baran
- Nail Disease Centre, 42 rue des Serbes, 06400 Cannes, France.
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23
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Coulombe PA, Tong X, Mazzalupo S, Wang Z, Wong P. Great promises yet to be fulfilled: defining keratin intermediate filament function in vivo. Eur J Cell Biol 2005; 83:735-46. [PMID: 15679118 DOI: 10.1078/0171-9335-00443] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Keratins are abundant proteins in epithelial cells, in which they occur as a cytoplasmic network of 10 - 12 nm wide intermediate filaments (IFs). They are encoded by a large family of conserved genes in mammals, with more than 50 individual members partitioned into two sequence types. A strict requirement for the heteropolymerization of type I and type II keratin proteins during filament formation underlies the pairwise transcriptional regulation of keratin genes. In addition, individual pairs are regulated in a tissue-type and differentiation-specific manner. Elucidating the rationale behind the diversity and differential distribution of keratin proteins offers the promise of novel insight into epithelial biology. At present, we know that keratin IFs act as resilient yet pliable scaffolds that endow epithelial cells with the ability to sustain mechanical and non-mechanical stresses. Accordingly, inherited mutations altering the coding sequence of keratins underlie several epithelial fragility disorders. In addition, keratin IFs influence the cellular response to pro-apoptotic signals in specific settings, and the routing of membrane proteins in polarized epithelia. Here we review studies focused on a subset of keratin genes, K6, K16 and K17, showing a complex regulation in vivo, including a widely known upregulation during wound repair and in diseased skin. Progress in defining the function of these and other keratins through gene manipulation in mice has been hampered by functional redundancy within the family. Still, detailed studies of the phenotype exhibited by K6 and K17 null mice yielded novel insight into the properties and function of keratin IFs in vivo.
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Affiliation(s)
- Pierre A Coulombe
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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24
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Bernot KM, Lee CH, Coulombe PA. A small surface hydrophobic stripe in the coiled-coil domain of type I keratins mediates tetramer stability. ACTA ACUST UNITED AC 2005; 168:965-74. [PMID: 15767464 PMCID: PMC2171788 DOI: 10.1083/jcb.200408116] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Intermediate filaments (IFs) are fibrous polymers encoded by a large family of differentially expressed genes that provide crucial structural support in the cytoplasm and nucleus in higher eukaryotes. The mechanisms involved in bringing together ∼16 elongated coiled-coil dimers to form an IF are poorly defined. Available evidence suggests that tetramer subunits play a key role during IF assembly and regulation. Through molecular modeling and site-directed mutagenesis, we document a hitherto unnoticed hydrophobic stripe exposed at the surface of coiled-coil keratin heterodimers that contributes to the extraordinary stability of heterotetramers. The inability of K16 to form urea-stable tetramers in vitro correlates with an increase in its turnover rate in vivo. The data presented support a specific conformation for the assembly competent IF tetramer, provide a molecular basis for their differential stability in vitro, and point to the physiological relevance associated with this property in vivo.
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Affiliation(s)
- Kelsie M Bernot
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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25
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Wong P, Domergue R, Coulombe PA. Overcoming functional redundancy to elicit pachyonychia congenita-like nail lesions in transgenic mice. Mol Cell Biol 2005; 25:197-205. [PMID: 15601842 PMCID: PMC538767 DOI: 10.1128/mcb.25.1.197-205.2005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Mutations affecting the coding sequence of intermediate filament (IF) proteins account for >30 disorders, including numerous skin bullous diseases, myopathies, neuropathies, and even progeria. The manipulation of IF genes in mice has been widely successful for modeling key features of such clinically distinct disorders. A notable exception is pachyonychia congenita (PC), a disorder in which the nail and other epithelial appendages are profoundly aberrant. Most cases of PC are due to mutations in one of the following keratin-encoding genes: K6, K16, and K17. Yet null alleles obliterating the function of both K6 genes (K6alpha and K6beta) or the K17 gene, as well as the targeted expression of a dominant-negative K6alpha mutant, elicit only a subset of PC-specific epithelial lesions (excluding that of the nail in mice). We show that newborn mice null for K6alpha, K6beta, and K17 exhibit severe lysis restricted to the nail bed epithelium, where all three genes are robustly expressed, providing strong evidence that this region of the nail unit is initially targeted in PC. Our findings point to significant redundancy among the multiple keratins expressed in hair and nail, which can be related to the common ancestry, clustered organization, and sequence relatedness of specific keratin genes.
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Affiliation(s)
- Pauline Wong
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe St., Baltimore, MD 21205, USA
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26
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Koch PJ, Roop DR. The role of keratins in epidermal development and homeostasis--going beyond the obvious. J Invest Dermatol 2004; 123:x-xi. [PMID: 15482464 DOI: 10.1111/j.0022-202x.2004.23495.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Peter J Koch
- Departments of Molecular & Cellular Biology and Dermatology, Baylor College of Medicine, Houston, Texas, USA
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27
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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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28
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Abstract
A large number of mutations in keratin genes underlie inherited tissue fragility disorders of epithelia. The genotype-phenotype correlations emerging from these studies provide a rich source of information about the function of keratins that would have taken decades to achieve by a purely transgenic approach. Human disease studies are being supplemented by engineered mouse mutant studies, which give access to the effects of genetic alterations unlikely to occur naturally. Evidence is emerging that the great diversity of keratins might be required to enable cells to adapt their structure in response to different signalling pathways.
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Affiliation(s)
- Rebecca M Porter
- Cancer Research UK Cell Structure Research Group, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dundee DD1 5EH, UK
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29
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Bernot KM, Coulombe PA, McGowan KM. Keratin 16 expression defines a subset of epithelial cells during skin morphogenesis and the hair cycle. J Invest Dermatol 2002; 119:1137-49. [PMID: 12445204 DOI: 10.1046/j.1523-1747.2002.19518.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The morphogenesis of skin epithelia and adult hair follicle cycling both require integrated signaling between the epithelium and underlying mesenchyme. Because of their unique regulation, keratin intermediate filaments represent useful markers for the analysis of determination and differentiation processes in complex epithelia, such as the skin. In this study, we analyzed the distribution of mouse type I keratin 16 during skin morphogenesis, in the adult hair cycle, and in challenged epidermis. In mature hair follicles, we find keratin 16 along with its type II keratin partner keratin 6 in the companion layer of the outer root sheath during anagen and in the club hair sheath during catagen and telogen. During embryonic development, the distribution of keratin 16 is uncoupled from its presumed polymerization partner, keratin 6. Keratin 16 initially localizes within early hair germs, but rapidly shifts to a subset of cells at the interface of basal and suprabasal cells above and around the hair germ. The presence of keratin 16 at the transition between mitotically active and differentiating cells is recapitulated in primary keratinocytes cultured in vitro and in phorbol 12-myristate 13-acetate-treated back skin in vivo. We propose that keratin 16 marks cells in an intermediate state of cellular properties in which keratinocytes retain the flexibility required for activities such as cell migration and even mitosis but are resilient enough to provide the structural integrity required of the early suprabasal layers in the context of development, adult hair cycling, and wound repair.
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Affiliation(s)
- Kelsie M Bernot
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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30
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Abstract
Intermediate filament (IF) proteins form the largest family of cytoskeletal proteins in mammalian cells. The function of these proteins has long been thought to be only structural. However, this single function does not explain their diverse tissue- and differentiation-specific expression patterns. Evidence is now emerging that IF also act as an important framework for the modulation and control of essential cell processes, in particular, signal transduction events. Here, we review the most recent developments in this growing and exciting new field.
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Affiliation(s)
- Jesus M Paramio
- Project on Cell and Molecular Biology and Gene Therapy, CIEMAT, Ave. Complutense 22, E-28040 Madrid, Spain.
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31
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McGowan KM, Tong X, Colucci-Guyon E, Langa F, Babinet C, Coulombe PA. Keratin 17 null mice exhibit age- and strain-dependent alopecia. Genes Dev 2002; 16:1412-22. [PMID: 12050118 PMCID: PMC186322 DOI: 10.1101/gad.979502] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Onset of type I keratin 17 (K17) synthesis marks the adoption of an appendageal fate within embryonic ectoderm, and its expression persists in specific cell types within mature hair, glands, and nail. We report that K17 null mice develop severe alopecia during the first week postbirth, correlating with hair fragility, alterations in follicular histology, and apoptosis in matrix cells. These alterations are incompletely penetrant and normalize starting with the first postnatal cycle. Absence of a hair phenotype correlates with a genetic strain-dependent compensation by related keratins, including K16. These findings reveal a crucial role for K17 in the structural integrity of the first hair produced and the survival of hair-producing cells. Given that identical inherited mutations in this gene can cause either pachyonychia congenita or steatocystoma multiplex, the features of this mouse model suggest that this clinical heterogeneity arises from a cell type-specific, genetically determined compensation by related keratins.
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Affiliation(s)
- Kevin M McGowan
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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32
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Santos M, Paramio JM, Bravo A, Ramirez A, Jorcano JL. The expression of keratin k10 in the basal layer of the epidermis inhibits cell proliferation and prevents skin tumorigenesis. J Biol Chem 2002; 277:19122-30. [PMID: 11889133 DOI: 10.1074/jbc.m201001200] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Forced expression of K10, a keratin normally expressed in postmitotic, terminally differentiating epidermal keratinocytes, inhibits the progression of the cell cycle in cultured cells (Paramio, J. M., Casanova, M. Ll., Segrelles, C., Mittnacht, S., Lane, E. B., and Jorcano, J. L. (1999) Mol. Cell. Biol. 19, 3086-3094). This process requires a functional retinoblastoma (pRb) gene product and is mediated by K10-induced inhibition of Akt and PKCzeta, two signaling intermediates belonging to the phosphoinositide (PI) 3-kinase signal transduction pathway (Paramio, J. M., Segrelles, C., Ruiz, S., and Jorcano, J. L. (2001) Mol. Cell. Biol. 21, 7449-7459). Extending earlier in vitro studies to the in vivo situation, this work analyzes the alterations found in transgenic mice that ectopically express K10 in the proliferative basal cells of the epidermis. Increased expression of K10 led to a hypoplastic and hyperkeratotic epidermis due to a dramatic decrease in skin keratinocyte proliferation in association with the inhibition of Akt and PKCzeta activities. The inhibition of cell proliferation and Akt and PKCzeta activities was also observed although to a minor extent in low hK10-expressing mice. These animals displayed no overt epidermal phenotype nor overexpression of K10. In these non-phenotypic mice, ectopic K10 expression also resulted in decreased skin tumorigenesis. Collectively, these data demonstrate that keratin K10 in vivo functions include the control of epithelial proliferation in skin epidermis.
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Affiliation(s)
- Mirentxu Santos
- Project on Cell and Molecular Biology and Gene Therapy, CIEMAT Av. Complutense 22, E-28040 Madrid, Spain
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33
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Coulombe PA, Omary MB. 'Hard' and 'soft' principles defining the structure, function and regulation of keratin intermediate filaments. Curr Opin Cell Biol 2002; 14:110-22. [PMID: 11792552 DOI: 10.1016/s0955-0674(01)00301-5] [Citation(s) in RCA: 493] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Keratins make up the largest subgroup of intermediate filament proteins and represent the most abundant proteins in epithelial cells. They exist as highly dynamic networks of cytoplasmic 10-12 nm filaments that are obligate heteropolymers involving type I and type II keratins. The primary function of keratins is to protect epithelial cells from mechanical and nonmechanical stresses that result in cell death. Other emerging functions include roles in cell signaling, the stress response and apoptosis, as well as unique roles that are keratin specific and tissue specific. The role of keratins in a number of human skin, hair, ocular, oral and liver diseases is now established and meshes well with the evidence gathered from transgenic mouse models. The phenotypes associated with defects in keratin proteins are subject to significant modulation by functional redundancy within the family and modifier genes as well. Keratin filaments undergo complex regulation involving post-translational modifications and interactions with self and with various classes of associated proteins.
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Affiliation(s)
- Pierre A Coulombe
- Department of Biological Chemistry, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
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34
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Bousquet O, Coulombe PA. Les kératines : un autre regard sur la biologie de la peau. Med Sci (Paris) 2002. [DOI: 10.1051/medsci/200218145] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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35
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Yamada S, Wirtz D, Coulombe PA. Pairwise assembly determines the intrinsic potential for self-organization and mechanical properties of keratin filaments. Mol Biol Cell 2002; 13:382-91. [PMID: 11809846 PMCID: PMC65095 DOI: 10.1091/mbc.01-10-0522] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2001] [Revised: 10/18/2001] [Accepted: 10/31/2001] [Indexed: 12/27/2022] Open
Abstract
Most type I and II keratin genes are spatially and temporally regulated in a pairwise manner in epithelial tissues, where they represent the major structural proteins. Epithelia can be partitioned into simple (single-layered) and complex (multilayered) types. We compared the structural and mechanical properties of natural keratin polymers occurring in complex (K5-K14) and simple (K8-K18) epithelia. The intrinsic properties of these distantly related keratin filaments, whether dispersed or bundled in vitro, were surprisingly similar in all respects when at high polymer concentration. When type I and II assembly partners were switched to give rise to mismatched polymers (K5-K18; K8-K14), the interfilament interactions, which determine the structural and mechanical properties of keratin polymers, were significantly altered. We also show that a K5-K16 polymer exhibits lesser elasticity than K5- K14, which may help explain the inability of K16 to fully rescue the skin blistering characteristic of K14 null mice. The property of self-interaction exhibited by keratin filaments is likely to assist their function in vivo and may account for the relative paucity of cytoplasmic and keratin-specific cross-linkers. Our findings underscore the fundamental importance of pairwise polymerization and have implications for the functional significance of keratin sequence diversity.
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Affiliation(s)
- Soichiro Yamada
- Department of Chemical Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA
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36
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Bousquet O, Ma L, Yamada S, Gu C, Idei T, Takahashi K, Wirtz D, Coulombe PA. The nonhelical tail domain of keratin 14 promotes filament bundling and enhances the mechanical properties of keratin intermediate filaments in vitro. J Cell Biol 2001; 155:747-54. [PMID: 11724817 PMCID: PMC2150872 DOI: 10.1083/jcb.200104063] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Keratin filaments arise from the copolymerization of type I and II sequences, and form a pancytoplasmic network that provides vital mechanical support to epithelial cells. Keratins 5 and 14 are expressed as a pair in basal cells of stratified epithelia, where they occur as bundled arrays of filaments. In vitro, bundles of K5-K14 filaments can be induced in the absence of cross-linkers, and exhibit enhanced resistance to mechanical strain. This property is not exhibited by copolymers of K5 and tailless K14, in which the nonhelical tail domain has been removed, or copolymers of K5 and K19, a type I keratin featuring a short tail domain. The purified K14 tail domain binds keratin filaments in vitro with specificity (kD approximately 2 microM). When transiently expressed in cultured cells, the K14 tail domain associates with endogenous keratin filaments. Utilization of the K14 tail domain as a bait in a yeast two-hybrid screen pulls out type I keratin sequences from a skin cDNA library. These data suggest that the tail domain of K14 contributes to the ability of K5-K14 filaments to self-organize into large bundles showing enhanced mechanical resilience in vitro.
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Affiliation(s)
- O Bousquet
- Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
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37
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Wawersik MJ, Mazzalupo S, Nguyen D, Coulombe PA. Increased levels of keratin 16 alter epithelialization potential of mouse skin keratinocytes in vivo and ex vivo. Mol Biol Cell 2001; 12:3439-50. [PMID: 11694579 PMCID: PMC60266 DOI: 10.1091/mbc.12.11.3439] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The process of wound repair in adult skin is complex, involving dermal contraction and epithelial migration to repair the lesion and restore the skin's barrier properties. At the wound edge, keratinocytes undergo many changes that engender an epithelialization behavior. The type II keratin 6 and type I keratins 16 and 17 are induced well before cell migration begins, but the role of these proteins is not understood. Forced expression of human K16 in skin epithelia of transgenic mice has been shown to cause dose-dependent skin lesions concomitant with alterations in keratin filament organization and in cell adhesion. Here we show, with the use of a quantitative assay, that these transgenic mice show a delay in the closure of full-thickness skin wounds in situ compared with wild-type and low-expressing K16 transgenic mice. We adapted and validated an ex vivo skin explant culture system to better assess epithelialization in a wound-like environment. Transgenic K16 explants exhibit a significant reduction of keratinocyte outgrowth in this setting. This delay is transgene dose-dependent, and is more severe when K16 is expressed in mitotic compared with post-mitotic keratinocytes. Various lines of evidence suggest that the mechanism(s) involved is complex and not strictly cell autonomous. These findings have important implications for the function of K16 in vivo.
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Affiliation(s)
- M J Wawersik
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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38
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Boulay A, Régnier CH, Anglard P, Stoll I, Tomasetto C, Rio MC. Transcription regulation and protein subcellular localization of the truncated basic hair keratin hHb1-DeltaN in human breast cancer cells. J Biol Chem 2001; 276:22954-64. [PMID: 11304540 DOI: 10.1074/jbc.m101687200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
An aberrant truncated hHb1 hair keratin transcript, named hHb1-DeltaN, was previously identified in breast carcinomas. No normal tissue tested so far, including hairy skin, expressed hHb1-DeltaN, indicating that hHb1-DeltaN is related to carcinogenesis. In the present study, we investigated the mechanism by which such truncated transcript was generated in breast cancer cell lines. We found that hHb1-DeltaN transcription is initiated at an unusual cryptic promoter within the fourth intron of the hHb1 gene and is dependent on two proximal Sp1 binding sites for its baseline activity. Moreover, hHb1-DeltaN transcription is increased in response to DNA demethylation by the 5-aza-2'-deoxycytidine drug. This induction is dependent on protein neosynthesis, indicating that an additional factor is required. In addition, we showed that the hHb1-DeltaN transcript is translated in vivo as a truncated hHb1 protein that is missing the 270 amino-terminal residues. The hHb1-DeltaN protein exhibits a filament pattern throughout the cytoplasm and partially co-localizes with cytokeratin filaments, indicating its participation in the cytoskeleton network. hHb1-DeltaN might alter the adhesive properties of cancer cells.
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Affiliation(s)
- A Boulay
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM U184/ULP BP 163, 67404 Illkirch Cedex, C.U. de Strasbourg, France
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39
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Reichelt J, Büssow H, Grund C, Magin TM. Formation of a normal epidermis supported by increased stability of keratins 5 and 14 in keratin 10 null mice. Mol Biol Cell 2001; 12:1557-68. [PMID: 11408568 PMCID: PMC37324 DOI: 10.1091/mbc.12.6.1557] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The expression of distinct keratin pairs during epidermal differentiation is assumed to fulfill specific and essential cytoskeletal functions. This is supported by a great variety of genodermatoses exhibiting tissue fragility because of keratin mutations. Here, we show that the loss of K10, the most prominent epidermal protein, allowed the formation of a normal epidermis in neonatal mice without signs of fragility or wound-healing response. However, there were profound changes in the composition of suprabasal keratin filaments. K5/14 persisted suprabasally at elevated protein levels, whereas their mRNAs remained restricted to the basal keratinocytes. This indicated a novel mechanism regulating keratin turnover. Moreover, the amount of K1 was reduced. In the absence of its natural partner we observed the formation of a minor amount of novel K1/14/15 filaments as revealed by immunogold electron microscopy. We suggest that these changes maintained epidermal integrity. Furthermore, suprabasal keratinocytes contained larger keratohyalin granules similar to our previous K10T mice. A comparison of profilaggrin processing in K10T and K10(-/-) mice revealed an accumulation of filaggrin precursors in the former but not in the latter, suggesting a requirement of intact keratin filaments for the processing. The mild phenotype of K10(-/-) mice suggests that there is a considerable redundancy in the keratin gene family.
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Affiliation(s)
- J Reichelt
- Institute of Genetics, University of Bonn, 53117 Bonn, Germany
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40
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Peters B, Kirfel J, Büssow H, Vidal M, Magin TM. Complete cytolysis and neonatal lethality in keratin 5 knockout mice reveal its fundamental role in skin integrity and in epidermolysis bullosa simplex. Mol Biol Cell 2001; 12:1775-89. [PMID: 11408584 PMCID: PMC37340 DOI: 10.1091/mbc.12.6.1775] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In human patients, a wide range of mutations in keratin (K) 5 or K14 lead to the blistering skin disorder epidermolysis bullosa simplex. Given that K14 deficiency does not lead to the ablation of a basal cell cytoskeleton because of a compensatory role of K15, we have investigated the requirement for the keratin cytoskeleton in basal cells by inactivating the K5 gene in mice. We report that the K5(-/-) mice die shortly after birth, lack keratin filaments in the basal epidermis, and are more severely affected than K14(-/-) mice. In contrast to the K14(-/-) mice, we detected a strong induction of the wound-healing keratin K6 in the suprabasal epidermis of cytolyzed areas of postnatal K5(-/-) mice. In addition, K5 and K14 mice differed with respect to tongue lesions. Moreover, we show that in the absence of K5 and other type II keratins, residual K14 and K15 aggregated along hemidesmosomes, demonstrating that individual keratins without a partner are stable in vivo. Our data indicate that K5 may be the natural partner of K15 and K17. We suggest that K5 null mutations may be lethal in human epidermolysis bullosa simplex patients.
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Affiliation(s)
- B Peters
- Institut fuer Genetik, Abteilung Molekulargenetik, Rheinische Friedrich-Wilhelms-Universitaet, 53117 Bonn, Germany
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41
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Wawersik M, Coulombe PA. Forced expression of keratin 16 alters the adhesion, differentiation, and migration of mouse skin keratinocytes. Mol Biol Cell 2000; 11:3315-27. [PMID: 11029038 PMCID: PMC14994 DOI: 10.1091/mbc.11.10.3315] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Injury to the skin results in an induction of keratins K6, K16, and K17 concomitant with activation of keratinocytes for reepithelialization. Forced expression of human K16 in skin epithelia of transgenic mice causes a phenotype that mimics several aspects of keratinocyte activation. Two types of transgenic keratinocytes, with forced expression of either human K16 or a K16-C14 chimeric cDNA, were analyzed in primary culture to assess the impact of K16 expression at a cellular level. High K16-C14-expressing and low K16-expressing transgenic keratinocytes behave similar to wild type in all aspects tested. In contrast, high K16-expressing transgenic keratinocytes show alterations in plating efficiency and calcium-induced differentiation, but proliferate normally. Migration of keratinocytes is reduced in K16 transgenic skin explants compared with controls. Finally, a subset of high K16-expressing transgenic keratinocytes develops major changes in the organization of keratin filaments in a time- and calcium concentration-dependent manner. These changes coincide with alterations in keratin content while the steady-state levels of K16 protein remain stable. We conclude that forced expression of K16 in progenitor skin keratinocytes directly impacts properties such as adhesion, differentiation, and migration, and that these effects depend upon determinants contained within its carboxy terminus.
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Affiliation(s)
- M Wawersik
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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Germain L, Carrier P, Auger FA, Salesse C, Guérin SL. Can we produce a human corneal equivalent by tissue engineering? Prog Retin Eye Res 2000; 19:497-527. [PMID: 10925241 DOI: 10.1016/s1350-9462(00)00005-7] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Tissue engineering is progressing rapidly. Bioengineered substitutes are already available for experimental applications and some clinical purposes such as skin replacement. This review focuses on the development of reconstructed human cornea in vitro by tissue engineering. Key elements to consider in the corneal reconstruction, such as the source for epithelial cells and keratocytes, are discussed and the various steps of production are presented. Since one application of this human model is to obtain a better understanding of corneal wound healing, the mechanisms of this phenomenon as well as the function played both by membrane-bound integrins and components from the extracellular matrix have also been addressed. The analysis of integrins by immunohistofluorescence labelling of our reconstructed human cornea revealed that beta(1), alpha(3), alpha(5), and alpha(6) integrin subunits were expressed but alpha(4) was not. Laminin, type VII collagen and fibronectin were also detected. Finally, the future challenges of corneal reconstruction by tissue engineering are discussed and the tremendous applications of such tissue produced in vitro for experimental as well as clinical purposes are considered.
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Affiliation(s)
- L Germain
- Laboratoire d'Organogénèse Expérimentale (LOEX), CHA Pavillon Saint-Sacrement, Qc, G1 S 4L8, Québec, Canada.
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43
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Wong P, Colucci-Guyon E, Takahashi K, Gu C, Babinet C, Coulombe PA. Introducing a null mutation in the mouse K6alpha and K6beta genes reveals their essential structural role in the oral mucosa. J Cell Biol 2000; 150:921-8. [PMID: 10953016 PMCID: PMC2175283 DOI: 10.1083/jcb.150.4.921] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Mammalian genomes feature multiple genes encoding highly related keratin 6 (K6) isoforms. These type II keratins show a complex regulation with constitutive and inducible components in several stratified epithelia, including the oral mucosa and skin. Two functional genes, K6alpha and K6beta, exist in a head-to-tail tandem array in mouse genomes. We inactivated these two genes simultaneously via targeting and homologous recombination. K6 null mice are viable and initially indistinguishable from their littermates. Starting at two to three days after birth, they show a growth delay associated with reduced milk intake and the presence of white plaques in the posterior region of dorsal tongue and upper palate. These regions are subjected to greater mechanical stress during suckling. Morphological analyses implicate the filiform papillae as being particularly sensitive to trauma in K6alpha/K6beta null mice, and establish the complete absence of keratin filaments in their anterior compartment. All null mice die about a week after birth. These studies demonstrate an essential structural role for K6 isoforms in the oral mucosa, and implicate filiform papillae as being the major stress bearing structures in dorsal tongue epithelium.
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Affiliation(s)
- Pauline Wong
- Department of Biological Chemistry and Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Emma Colucci-Guyon
- Unité de Biologie du Développement, Institut Pasteur, 75724 Paris CEDEX 15, France
| | - Kenzo Takahashi
- Department of Dermatology, Kyoto University, Kyoto 606-8507, Japan
| | - Changhong Gu
- Department of Biological Chemistry and Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Charles Babinet
- Unité de Biologie du Développement, Institut Pasteur, 75724 Paris CEDEX 15, France
| | - Pierre A. Coulombe
- Department of Biological Chemistry and Department of Dermatology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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McGowan KM, Coulombe PA. Keratin 17 expression in the hard epithelial context of the hair and nail, and its relevance for the pachyonychia congenita phenotype. J Invest Dermatol 2000; 114:1101-7. [PMID: 10844551 DOI: 10.1046/j.1523-1747.2000.00986.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The hard-keratin-containing portion of the murine hair shaft displays a positive immunoreactivity with an antibody against the soft epithelial keratin, K17. The K17-expressing cell population is located in the medulla compartment of the hair. Consistent with this observation, K17-containing cells also occur in the presumptive medulla precursor cells located in the hair follicle matrix. Western blot analysis of hair extracts prepared from a number of mouse strains confirms this observation and suggests that K17 expression in the hair shaft is a general trait in this species. The expression of K17 in human hair extracts is restricted to eyebrow and facial hair samples. These are the major sites for the occurrence of the pili torti (twisted hair) phenotype in the type 2 (Jackson-Lawler) form of pachyonychia congenita, previously shown to arise from inherited K17 mutations. Given that all forms of pachyonychia congenita show an involvement of the nail, we compared the expression of the two other genes mutated in pachyonychia congenita diseases, K6 and K16, with that of K17 in human nail. All three keratins are abundantly expressed within the nail bed epithelium, whereas K17 protein is expressed in the nail matrix, which contains the epithelial cell precursors for the nail plate. Our data suggest a role for K17 in the formation and maintenance of various skin appendages and directly support the concept that pachyonychia congenita is a disease of the nail bed.
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Affiliation(s)
- K M McGowan
- Departments of Biological Chemistry and Dermatology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Herrmann H, Aebi U. Intermediate filaments and their associates: multi-talented structural elements specifying cytoarchitecture and cytodynamics. Curr Opin Cell Biol 2000; 12:79-90. [PMID: 10679360 DOI: 10.1016/s0955-0674(99)00060-5] [Citation(s) in RCA: 349] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The assembly of intermediate filament (IF) arrays involves the recruitment of a complex set of cell-type-specific IF-associated proteins. Some of them are integral membrane proteins, others act as crosslinking proteins with vectorial binding activities, and yet others comprise motor proteins. In vivo IFs appear to be predominantly heteropolymers, although in vitro several IF proteins (e.g. vimentin, desmin, neurofilament (NF)-L and the nuclear lamins) do self-assemble into IF-like polymers. In contrast, NF-M, NF-H, nestin, synemin and paranemin, all bona fide IF proteins, are unable to self-assemble into IFs either in vitro or in vivo. The individual IF proteins of this large multigene family are chemically heterogeneous, exhibiting different assembly kinetics and yielding discrete types of filaments. The unique physical properties and interaction capabilities of these distinct IF molecular building blocks, in combination with accessory proteins, mediate the generation of a highly dynamic and interconnected, cell-type-specific cytoarchitecture.
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Affiliation(s)
- H Herrmann
- Division of Cell Biology, German Cancer Research Center, Heidelberg, D-69120, Germany.
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