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Baardman R, Lemmink HH, Yenamandra VK, Commandeur-Jan SZ, Viel M, Kooi KA, Diercks GFH, Meijer R, van Geel M, Scheffer H, Sinke RJ, Sikkema-Raddatz B, Bolling MC, van den Akker PC. Evolution of genome diagnostics in epidermolysis bullosa: Unveiling the power of next-generation sequencing. J Eur Acad Dermatol Venereol 2024. [PMID: 38465480 DOI: 10.1111/jdv.19938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 02/05/2024] [Indexed: 03/12/2024]
Abstract
BACKGROUND Genome diagnostics is considered gold standard diagnostics for epidermolysis bullosa (EB), a phenotypically and genetically heterogeneous group of rare disorders characterized by blistering and wounding of mucocutaneous tissues. EB is caused by pathogenic variants in genes encoding proteins of the dermo-epidermal junction. Accurate genetic diagnosis of EB is crucial for prognostication, counselling and precision-medicine. Genome diagnostics for EB started in 1991 with the introduction of Sanger sequencing (SS), analysing one gene at a time. In 2013, SS was superseded by next-generation sequencing (NGS), that allow for high-throughput sequencing of multiple genes in parallel. Several studies have shown a beneficial role for NGS in EB diagnostics, but its true benefit has not been quantified. OBJECTIVES To determine the benefit of NGS in EB by systematically evaluating the performance of different genome diagnostics used over time based on robust data from the Dutch EB Registry. METHODS The diagnostic performances of SS and NGS were systematically evaluated in a retrospective observational study including all index cases with a clinical diagnosis of EB in whom genome diagnostics was performed between 01 January 1994 and 01 January 2022 (n = 308), registered at the Dutch EB Expertise Centre. RESULTS Over time, a genetic diagnosis was made in 289/308 (94%) EB cases. The diagnostic yield increased from 89% (SS) to 95% (NGS). Most importantly, NGS significantly reduced diagnostic turnaround time (39 days vs. 211 days, p < 0.001). The likelihood of detecting variants of uncertain significance and additional findings increased from 5% and 1% (SS) to 22% and 13% (NGS) respectively. CONCLUSIONS Our study quantifies the benefit of NGS-based methods and demonstrate they have had a major impact on EB diagnostics through an increased diagnostic yield and a dramatically decreased turnaround time (39 days). Although our diagnostic yield is high (95%), further improvement of genome diagnostics is urgently needed to provide a genetic diagnosis in all EB patients.
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Affiliation(s)
- R Baardman
- Department of Dermatology, UMCG Centers of Expertise for Blistering Diseases and Genodermatoses, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - H H Lemmink
- Department of Genetics, UMCG Centers of Expertise for Blistering Diseases and Genodermatoses, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - V K Yenamandra
- Academy of Scientific and Innovative Research South Campus, CSIR-Institute of Genomics and Integrative Biology (IGIB), New Delhi, India
| | - S Z Commandeur-Jan
- Department of Genetics, UMCG Centers of Expertise for Blistering Diseases and Genodermatoses, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - M Viel
- Department of Genetics, UMCG Centers of Expertise for Blistering Diseases and Genodermatoses, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - K A Kooi
- Department of Genetics, UMCG Centers of Expertise for Blistering Diseases and Genodermatoses, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - G F H Diercks
- Department of Dermatology, UMCG Centers of Expertise for Blistering Diseases and Genodermatoses, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Department of Pathology, UMCG Centers of Expertise for Blistering Diseases and Genodermatoses, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - R Meijer
- Department of Genetics, University Medical Center Nijmegen, University of Nijmegen, Nijmegen, The Netherlands
| | - M van Geel
- Department of Genetics, Maastricht University Medical Center, University of Maastricht, Maastricht, The Netherlands
| | - H Scheffer
- Department of Genetics, University Medical Center Nijmegen, University of Nijmegen, Nijmegen, The Netherlands
| | - R J Sinke
- Department of Genetics, UMCG Centers of Expertise for Blistering Diseases and Genodermatoses, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - B Sikkema-Raddatz
- Department of Genetics, UMCG Centers of Expertise for Blistering Diseases and Genodermatoses, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - M C Bolling
- Department of Dermatology, UMCG Centers of Expertise for Blistering Diseases and Genodermatoses, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - P C van den Akker
- Department of Dermatology, UMCG Centers of Expertise for Blistering Diseases and Genodermatoses, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Department of Genetics, UMCG Centers of Expertise for Blistering Diseases and Genodermatoses, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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Banner L, Cohen A, McGrath L, Nikbakht N, South AP. A novel KRT14 null mutation leads to autosomal recessive epidermolysis bullosa simplex. Clin Exp Dermatol 2023; 48:431-433. [PMID: 36757906 DOI: 10.1093/ced/llac129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/13/2022] [Accepted: 12/19/2022] [Indexed: 01/22/2023]
Abstract
We describe a novel homozygous KRT14 (also known as K14) mutation detected in a patient with a relatively mild form of epidermolysis bullosa simplex (EBS). Our patient harbours loss of function of both alleles of the KRT14 gene. This is the 16th reported mutation of recessive EBS in KRT14.
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Affiliation(s)
- Lauren Banner
- Department of Dermatology and Cutaneous Biology, Philadelphia, PA, USA
| | - Alexa Cohen
- Department of Dermatology and Cutaneous Biology, Philadelphia, PA, USA
| | - Lauren McGrath
- Department of Dermatology and Cutaneous Biology, Philadelphia, PA, USA
| | - Neda Nikbakht
- Department of Dermatology and Cutaneous Biology, Philadelphia, PA, USA
| | - Andrew P South
- Department of Dermatology and Cutaneous Biology, Philadelphia, PA, USA
- The Joan and Joel Rosenbloom Research Center for Fibrotic Diseases, Philadelphia, PA, USA
- Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
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3
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Epidermolysis Bullosa—A Different Genetic Approach in Correlation with Genetic Heterogeneity. Diagnostics (Basel) 2022; 12:diagnostics12061325. [PMID: 35741135 PMCID: PMC9222206 DOI: 10.3390/diagnostics12061325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/23/2022] [Accepted: 05/25/2022] [Indexed: 11/17/2022] Open
Abstract
Epidermolysis bullosa is a heterogeneous group of rare genetic disorders characterized by mucocutaneous fragility and blister formation after minor friction or trauma. There are four major epidermolysis bullosa types based on the ultrastructural level of tissue cleavage: simplex, junctional, dystrophic, and Kindler epidermolysis bullosa. They are caused by mutations in genes that encode the proteins that are part of the hemidesmosomes and focal adhesion complex. Some of these disorders can be associated with extracutaneous manifestations, which are sometimes fatal. They are inherited in an autosomal recessive or autosomal dominant manner. This review is focused on the phenomena of heterogeneity (locus, allelic, mutational, and clinical) in epidermolysis bullosa, and on the correlation genotype–phenotype.
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Whole exome sequencing in Alopecia Areata identifies rare variants in KRT82. Nat Commun 2022; 13:800. [PMID: 35145093 PMCID: PMC8831607 DOI: 10.1038/s41467-022-28343-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 11/22/2021] [Indexed: 01/31/2023] Open
Abstract
Alopecia areata is a complex genetic disease that results in hair loss due to the autoimmune-mediated attack of the hair follicle. We previously defined a role for both rare and common variants in our earlier GWAS and linkage studies. Here, we identify rare variants contributing to Alopecia Areata using a whole exome sequencing and gene-level burden analyses approach on 849 Alopecia Areata patients compared to 15,640 controls. KRT82 is identified as an Alopecia Areata risk gene with rare damaging variants in 51 heterozygous Alopecia Areata individuals (6.01%), achieving genome-wide significance (p = 2.18E−07). KRT82 encodes a hair-specific type II keratin that is exclusively expressed in the hair shaft cuticle during anagen phase, and its expression is decreased in Alopecia Areata patient skin and hair follicles. Finally, we find that cases with an identified damaging KRT82 variant and reduced KRT82 expression have elevated perifollicular CD8 infiltrates. In this work, we utilize whole exome sequencing to successfully identify a significant Alopecia Areata disease-relevant gene, KRT82, and reveal a proposed mechanism for rare variant predisposition leading to disrupted hair shaft integrity. Common variants have been discovered to be associated with Alopecia Areata; however, rare variants have been less well studied. Here, the authors use whole-exome sequencing to identify associated rare variants in the hair keratin gene KRT82. Further, they find that individuals with Alopecia Areata have reduced expression of KRT82 in the skin and hair follicle.
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5
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Molecular Modeling of Pathogenic Mutations in the Keratin 1B Domain. Int J Mol Sci 2020; 21:ijms21186641. [PMID: 32927888 PMCID: PMC7555247 DOI: 10.3390/ijms21186641] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 09/06/2020] [Accepted: 09/07/2020] [Indexed: 12/29/2022] Open
Abstract
Keratin intermediate filaments constitute the primary cytoskeletal component of epithelial cells. Numerous human disease phenotypes related to keratin mutation remain mechanistically elusive. Our recent crystal structures of the helix 1B heterotetramer from keratin 1/10 enabled further investigation of the effect of pathologic 1B domain mutations on keratin structure. We used our highest resolution keratin 1B structure as a template for homology-modeling the 1B heterotetramers of keratin 5/14 (associated with blistering skin disorders), keratin 8/18 (associated with liver disease), and keratin 74/28 (associated with hair disorder). Each structure was examined for the molecular alterations caused by incorporating pathogenic 1B keratin mutations. Structural modeling indicated keratin 1B mutations can harm the heterodimer interface (R265PK5, L311RK5, R211PK14, I150VK18), the tetramer interface (F231LK1, F274SK74), or higher-order interactions needed for mature filament formation (S233LK1, L311RK5, Q169EK8, H128LK18). The biochemical changes included altered hydrophobic and electrostatic interactions, and altered surface charge, hydrophobicity or contour. Together, these findings advance the genotype-structurotype-phenotype correlation for keratin-based human diseases.
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6
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Lalor L, Titeux M, Palisson F, Fuentes I, Yubero MJ, Tasanen K, Huilaja L, Has C, Tadini G, Haggstrom AN, Hovnanian A, Lucky AW. Epidermolysis bullosa simplex-generalized severe type due to keratin 5 p.Glu477Lys mutation: Genotype-phenotype correlation and in silico modeling analysis. Pediatr Dermatol 2019; 36:132-138. [PMID: 30515866 DOI: 10.1111/pde.13722] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND/OBJECTIVES Epidermolysis bullosa is a group of diseases caused by mutations in skin structural proteins. Availability of genetic sequencing makes identification of causative mutations easier, and genotype-phenotype description and correlation are important. We describe six patients with a keratin 5 mutation resulting in a glutamic acid to lysine substitution at position 477 (p.Glu477Lys) who have a distinctive, severe and sometimes fatal phenotype. We also perform in silico modeling to show protein structural changes resulting in instability. METHODS In this case series, we collected clinical data from six patients with this mutation identified from their national or local epidermolysis bullosa databases. We performed in silico modeling of the keratin 5-keratin 14 coil 2B complex using CCBuilder and rendered with Pymol (Schrodinger, LLC, New York, NY). RESULTS Features include aplasia cutis congenita, generalized blistering, palmoplantar keratoderma, onychodystrophy, airway and developmental abnormalities, and a distinctive reticulated skin pattern. Our in silico model of the keratin 5 p.Glu477Lys mutation predicts conformational change and modification of the surface charge of the keratin heterodimer, severely impairing filament stability. CONCLUSIONS Early recognition of the features of this genotype will improve care. In silico analysis of mutated keratin structures provides useful insights into structural instability.
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Affiliation(s)
- Leah Lalor
- Division of Pediatric Dermatology, MCW Department of Dermatology, Milwaukee, Wisconsin
| | - Matthias Titeux
- Laboratory of Genetic Skin Diseases, Inserm UMR1163, Imagine Institute, Paris, France.,University Paris Descartes - Sorbonne Paris Cite, Paris, France
| | - Francis Palisson
- Fundacion DEBRA Chile, Santiago, Chile.,Facultad de Medicina, Clinica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Ignacia Fuentes
- Fundacion DEBRA Chile, Santiago, Chile.,Centro de Genetica y Genomica, Facultad de Medicina, Clinica Alemana Universidad del Desarrollo, Santiago, Chile
| | - María J Yubero
- Fundacion DEBRA Chile, Santiago, Chile.,Facultad de Medicina, Clinica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Kaisa Tasanen
- Department of Dermatology, Pedego Research Unit, Oulu Center for Cell-Matrix Research, MRC Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland
| | - Laura Huilaja
- Department of Dermatology, Pedego Research Unit, Oulu Center for Cell-Matrix Research, MRC Oulu, University of Oulu and Oulu University Hospital, Oulu, Finland
| | - Cristina Has
- Department of Dermatology, Medical Center - University of Freiburg, Freiburg, Germany
| | - Gianluca Tadini
- Pediatric Dermatology, Fondazione IRCC Ca'Granda - Ospedale Maggiore Policlinico di Milano, Milan, Italy
| | - Anita N Haggstrom
- Department of Dermatology and Pediatrics, Indiana University, Indianapolis, Indiana
| | - Alain Hovnanian
- Laboratory of Genetic Skin Diseases, Inserm UMR1163, Imagine Institute, Paris, France.,University Paris Descartes - Sorbonne Paris Cite, Paris, France
| | - Anne W Lucky
- Epidermolysis Bullosa Center, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
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7
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Khani P, Ghazi F, Zekri A, Nasri F, Behrangi E, Aghdam AM, Mirzaei H. Keratins and epidermolysis bullosa simplex. J Cell Physiol 2018; 234:289-297. [PMID: 30078200 DOI: 10.1002/jcp.26898] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Accepted: 06/12/2018] [Indexed: 11/10/2022]
Abstract
Keratin intermediate filaments play an important role in maintaining the integrity of the skin structure. Understanding the importance of this subject is possible with the investigation of keratin defects in epidermolysis bullosa simplex (EBS). Nowadays, in addition to clinical criteria, new molecular diagnostic methods, such as next generation sequencing, can help to distinguish the subgroups of EBS more precisely. Because the most important and most commonly occurring molecular defects in these patients are the defects of keratins 5 and14 (KRT5 and KRT14), comprehending the nature structure of these proteins and their involved processes can be very effective in understanding the pathophysiology of this disease and providing new and effective therapeutic platforms to treat it. Here, we summarized the various aspects of the presence of KRT5 and KRT14 in the epidermis, their relation to the incidence and severity of EBS phenotypes, and the processes with which these proteins can affect them.
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Affiliation(s)
- Pouria Khani
- Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Farideh Ghazi
- Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Ali Zekri
- Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Farzad Nasri
- Department of Medical Immunology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Elham Behrangi
- Department of Dermatology and Laser Surgery, Clinical Research Center, Rasoul-e-Akram Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Arad Mobasher Aghdam
- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hamed Mirzaei
- Department of Medical Biotechnology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
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8
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Nagai H, Oiso N, Tomida S, Sakai K, Fujiwara S, Nakamachi Y, Kawano S, Kawada A, Nishio K, Nishigori C. Epidermolysis bullosa simplex with mottled pigmentation with noncicatricial alopecia: identification of a recurrent p.P25L mutation inKRT5in four affected family members. Br J Dermatol 2015; 174:633-5. [DOI: 10.1111/bjd.14083] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- H. Nagai
- Division of Dermatology; Department of Internal Medicine; Kobe University Graduate School of Medicine; 7-5-1 Kusunoki-cho, Chuo-ku Kobe 650-0017 Japan
| | - N. Oiso
- Department of Dermatology; Kinki University Faculty of Medicine; Osaka-Sayama Japan
| | - S. Tomida
- Department of Genome Biology; Kinki University Faculty of Medicine; Osaka-Sayama Japan
| | - K. Sakai
- Department of Genome Biology; Kinki University Faculty of Medicine; Osaka-Sayama Japan
| | - S. Fujiwara
- Division of Dermatology; Department of Internal Medicine; Kobe University Graduate School of Medicine; 7-5-1 Kusunoki-cho, Chuo-ku Kobe 650-0017 Japan
| | - Y. Nakamachi
- Department of Clinical Laboratory; Kobe University Hospital; Kobe Japan
| | - S. Kawano
- Division of Laboratory Medicine; Department of Internal Medicine; Kobe University Graduate School of Medicine; 7-5-1 Kusunoki-cho, Chuo-ku Kobe 650-0017 Japan
| | - A. Kawada
- Department of Dermatology; Kinki University Faculty of Medicine; Osaka-Sayama Japan
| | - K. Nishio
- Department of Genome Biology; Kinki University Faculty of Medicine; Osaka-Sayama Japan
| | - C. Nishigori
- Division of Dermatology; Department of Internal Medicine; Kobe University Graduate School of Medicine; 7-5-1 Kusunoki-cho, Chuo-ku Kobe 650-0017 Japan
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9
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Cao YA, Hickerson RP, Seegmiller BL, Grapov D, Gross MM, Bessette MR, Phinney BS, Flores MA, Speaker TJ, Vermeulen A, Bravo AA, Bruckner AL, Milstone LM, Schwartz ME, Rice RH, Kaspar RL. Gene expression profiling in pachyonychia congenita skin. J Dermatol Sci 2015; 77:156-65. [PMID: 25656049 DOI: 10.1016/j.jdermsci.2015.01.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 01/05/2015] [Accepted: 01/07/2015] [Indexed: 01/26/2023]
Abstract
BACKGROUND Pachyonychia congenita (PC) is a skin disorder resulting from mutations in keratin (K) proteins including K6a, K6b, K16, and K17. One of the major symptoms is painful plantar keratoderma. The pathogenic sequelae resulting from the keratin mutations remain unclear. OBJECTIVE To better understand PC pathogenesis. METHODS RNA profiling was performed on biopsies taken from PC-involved and uninvolved plantar skin of seven genotyped PC patients (two K6a, one K6b, three K16, and one K17) as well as from control volunteers. Protein profiling was generated from tape-stripping samples. RESULTS A comparison of PC-involved skin biopsies to adjacent uninvolved plantar skin identified 112 differentially-expressed mRNAs common to patient groups harboring K6 (i.e., both K6a and K6b) and K16 mutations. Among these mRNAs, 25 encode structural proteins including keratins, small proline-rich and late cornified envelope proteins, 20 are related to metabolism and 16 encode proteases, peptidases, and their inhibitors including kallikrein-related peptidases (KLKs), and serine protease inhibitors (SERPINs). mRNAs were also identified to be differentially expressed only in K6 (81) or K16 (141) patient samples. Furthermore, 13 mRNAs were identified that may be involved in pain including nociception and neuropathy. Protein profiling, comparing three K6a plantar tape-stripping samples to non-PC controls, showed changes in the PC corneocytes similar, but not identical, to the mRNA analysis. CONCLUSION Many differentially-expressed genes identified in PC-involved skin encode components critical for skin barrier homeostasis including keratinocyte proliferation, differentiation, cornification, and desquamation. The profiling data provide a foundation for unraveling the pathogenesis of PC and identifying targets for developing effective PC therapeutics.
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Affiliation(s)
- Yu-An Cao
- TransDerm Inc., Santa Cruz, CA 95060, USA
| | | | | | - Dmitry Grapov
- University of California at Davis, Davis, CA 95616, USA
| | - Maren M Gross
- Dharmacon part of GE Healthcare, Lafayette, CO 80026, USA
| | | | | | | | | | | | - Albert A Bravo
- Podiatric Medicine and Surgery, Pittsfield, MA 01201, USA
| | - Anna L Bruckner
- University of Colorado School of Medicine, Aurora, CO 80045, USA
| | | | - Mary E Schwartz
- Pachyonychia Congenita Project, Salt Lake City, UT 84109, USA
| | - Robert H Rice
- University of California at Davis, Davis, CA 95616, USA
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10
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Banerjee S, Wu Q, Yu P, Qi M, Li C. In silico analysis of all point mutations on the 2B domain of K5/K14 causing epidermolysis bullosa simplex: a genotype–phenotype correlation. MOLECULAR BIOSYSTEMS 2014; 10:2567-77. [DOI: 10.1039/c4mb00138a] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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11
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Paris F, Hurtado C, Azón A, Aguado L, Vizmanos JL. A newKRT16mutation associated with a phenotype of pachyonychia congenita. Exp Dermatol 2013; 22:838-9. [DOI: 10.1111/exd.12262] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/04/2013] [Indexed: 11/28/2022]
Affiliation(s)
- Francesc Paris
- Department of Biochemistry & Genetics; School of Sciences; University of Navarra; Pamplona Spain
| | - Cristina Hurtado
- Department of Biochemistry & Genetics; School of Sciences; University of Navarra; Pamplona Spain
| | - Antoni Azón
- Department of Dermatology; University Hospital Sant Joan; Universitat Rovira i Virgili; Reus Spain
| | - Leyre Aguado
- Department of Dermatology; Clínica Universidad de Navarra; Pamplona Spain
| | - José L. Vizmanos
- Department of Biochemistry & Genetics; School of Sciences; University of Navarra; Pamplona Spain
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12
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Kubo A, Oura Y, Hirano T, Aoyama Y, Sato S, Nakamura K, Takae Y, Amagai M. Collapse of the keratin filament network through the expression of mutant keratin 6c observed in a case of focal plantar keratoderma. J Dermatol 2013; 40:553-7. [DOI: 10.1111/1346-8138.12185] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 04/03/2013] [Indexed: 01/27/2023]
Affiliation(s)
| | - Yuiko Oura
- Department of Dermatology; Keio University School of Medicine; Tokyo; Japan
| | | | - Yumi Aoyama
- Department of Dermatology; Okayama University Graduate School of Medicine; Okayama; Japan
| | - Showbu Sato
- Department of Dermatology; Keio University School of Medicine; Tokyo; Japan
| | - Kaori Nakamura
- Department of Dermatology; Saitama Medical Center; Saitama; Japan
| | - Yujiro Takae
- Department of Dermatology; Keio University School of Medicine; Tokyo; Japan
| | - Masayuki Amagai
- Department of Dermatology; Keio University School of Medicine; Tokyo; Japan
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13
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Natsuga K, Nishie W, Smith BJ, Shinkuma S, Smith TA, Parry DAD, Oiso N, Kawada A, Yoneda K, Akiyama M, Shimizu H. Consequences of two different amino-acid substitutions at the same codon in KRT14 indicate definitive roles of structural distortion in epidermolysis bullosa simplex pathogenesis. J Invest Dermatol 2011; 131:1869-76. [PMID: 21593775 DOI: 10.1038/jid.2011.143] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Numerous inherited diseases develop due to missense mutations, leading to an amino-acid substitution. Whether an amino-acid change is pathogenic depends on the level of deleterious effects caused by the amino-acid alteration. We show an example of different structural and phenotypic consequences caused by two individual amino-acid changes at the same position. Epidermolysis bullosa simplex (EBS) is a genodermatosis resulting from KRT5 or KRT14 mutations. Mutation analysis of an EBS family revealed that affected individuals were heterozygous for a, to our knowledge, previously unreported mutation of c.1237G>C (p.Ala413Pro) in KRT14. Interestingly, 2 of 100 unrelated normal controls were heterozygous, and 1 of the 100 was homozygous for a different mutation in this position, c.1237G>A (p.Ala413Thr). In silico modeling of the protein demonstrated deleterious structural effects from proline substitution but not from threonine substitution. In vitro transfection studies revealed a significantly larger number of keratin-clumped cells in HaCaT cells transfected with mutant KRT14 complementary DNA (cDNA) harboring p.Ala413Pro than those transfected with wild-type KRT14 cDNA or mutant KRT14 cDNA harboring p.Ala413Thr. These results show that changes in two distinct amino acids at a locus are destined to elicit different phenotypes due to the degree of structural distortion resulting from the amino-acid alterations.
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Affiliation(s)
- Ken Natsuga
- Department of Dermatology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
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14
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Bolling MC, Lemmink HH, Jansen GHL, Jonkman MF. Mutations in KRT5 and KRT14 cause epidermolysis bullosa simplex in 75% of the patients. Br J Dermatol 2011; 164:637-44. [PMID: 21375516 DOI: 10.1111/j.1365-2133.2010.10146.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Epidermolysis bullosa simplex (EBS) is a mechanobullous genodermatosis that may be caused by mutations in the genes KRT5 and KRT14 encoding the basal epidermal keratins 5 (K5) and 14 (K14). Three main clinical subtypes of EBS exist, differing in onset, distribution and severity of skin blistering. Previous reports of KRT5 and KRT14 mutations suggest a correlation between the location of the mutation and the severity of the associated EBS phenotype. OBJECTIVES The prevalence of KRT5/KRT14 mutations and the genotype-phenotype correlation in the largest tissue-confirmed EBS population is investigated. METHODS KRT5 and KRT14 genomic DNA and cDNA sequences of 76 clinically well-defined unrelated EBS probands were amplified and then subjected to direct sequencing and product length analysis. Immunofluorescence microscopy on patients' skin biopsies with antibodies against K5 and K14 was performed to study protein expression. RESULTS In 57 of 76 (75%) probands 41 different KRT5 and KRT14 mutations were identified, of which 12 were novel. Mutations affecting the highly conserved helix boundary motifs of the rod domains of K5 and K14, and the K14 helix initiation motif in particular, were associated with the severest, EBS Dowling-Meara, phenotype. In 21 EBS probands (37%) the mutation was de novo. In 19 probands (25%) KRT5 or KRT14 mutations were excluded. CONCLUSIONS The phenotype-genotype correlation observed in this large EBS population underscores the importance of helix boundary motifs for keratin assembly. Only three-quarters of biopsy-confirmed EBS probands have KRT5 or KRT14 mutations, indicating genetic heterogeneity in EBS. Alternative gene candidates are discussed.
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Affiliation(s)
- M C Bolling
- Center for Blistering Diseases, Department of Dermatology, University Medical Center Groningen, the Netherlands.
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Jeřábková B, Marek J, Bučková H, Kopečková L, Veselý K, Valíčková J, Fajkus J, Fajkusová L. Keratin mutations in patients with epidermolysis bullosa simplex: correlations between phenotype severity and disturbance of intermediate filament molecular structure. Br J Dermatol 2010; 162:1004-13. [DOI: 10.1111/j.1365-2133.2009.09626.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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16
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Jeřábková B, Marek J, Bučková H, Kopečková L, Veselý K, Valíčková J, Fajkus J, Fajkusová L. Keratin mutations in patients with epidermolysis bullosa simplex: correlations between phenotype severity and disturbance of intermediate filament molecular structure. Br J Dermatol 2010. [DOI: 10.1111/j.1365-2133.2010.09626.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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17
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Kang TW, Lee JS, Kim SE, Oh SW, Kim SC. Novel and recurrent mutations in Keratin 5 and 14 in Korean patients with Epidermolysis bullosa simplex. J Dermatol Sci 2010; 57:90-4. [DOI: 10.1016/j.jdermsci.2009.12.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Revised: 10/24/2009] [Accepted: 12/03/2009] [Indexed: 10/20/2022]
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18
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Chamcheu J, Virtanen M, Navsaria H, Bowden P, Vahlquist A, Törmä H. Epidermolysis bullosa simplex due to KRT5
mutations: mutation-related differences in cellular fragility and the protective effects of trimethylamine N
-oxide in cultured primary keratinocytes. Br J Dermatol 2010; 162:980-9. [DOI: 10.1111/j.1365-2133.2009.09615.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Shimomura Y, Wajid M, Weiser J, Kraemer L, Christiano AM. Mutations in the keratin 9 gene in Pakistani families with epidermolytic palmoplantar keratoderma. Clin Exp Dermatol 2009; 35:759-64. [PMID: 19874353 DOI: 10.1111/j.1365-2230.2009.03700.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Keratins are heteropolymeric proteins that form the intermediate filament cytoskeleton in epithelial cells. The common basic structure of all keratins is organized in a central α-helical rod domain flanked by nonhelical, variable head and tail regions. Most mutations in keratins are found in the central α-helical rod domain. Keratin 9 (K9) is expressed only in the suprabasal layers of palmoplantar epidermis. Mutations in the keratin 9 gene (KRT9) have been shown to cause epidermolytic palmoplantar keratoderma (EPPK; OMIM 144200), an autosomal dominant genodermatosis characterized clinically by diffuse hyperkeratosis limited to the palms and soles, and histologically by epidermolysis in suprabasal layers of the epidermis. AIM To elucidate the genetic basis of EPPK in five Pakistani families. METHODS Using microsatellite markers localized to the areas around the type I keratin gene cluster on chromosome 17q21, genotyping of these families was performed, followed by sequencing of the KRT9 gene. RESULTS The analysis resulted in the identification of two novel (p.M157K and p.Y454H) and two recurrent (p.M157T and p.R163Q) mutations in the KRT9 of all five families. All mutations occurred within the highly conserved helix initiation or termination motif of K9. CONCLUSIONS The affected members of all five families possess mutations in the KRT9 gene that severely affect heterodimer formation with the type II keratin partner. The results of our study further underscore the crucial role of K9 protein in the palmoplantar epidermis.
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Affiliation(s)
- Y Shimomura
- Department of Dermatology, Columbia University, New York, NY 10032, USA
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20
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Herrmann H, Strelkov SV, Burkhard P, Aebi U. Intermediate filaments: primary determinants of cell architecture and plasticity. J Clin Invest 2009; 119:1772-83. [PMID: 19587452 DOI: 10.1172/jci38214] [Citation(s) in RCA: 220] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Intermediate filaments (IFs) are major constituents of the cytoskeleton and nuclear boundary in animal cells. They are of prime importance for the functional organization of structural elements. Depending on the cell type, morphologically similar but biochemically distinct proteins form highly viscoelastic filament networks with multiple nanomechanical functions. Besides their primary role in cell plasticity and their established function as cellular stress absorbers, recently discovered gene defects have elucidated that structural alterations of IFs can affect their involvement both in signaling and in controlling gene regulatory networks. Here, we highlight the basic structural and functional properties of IFs and derive a concept of how mutations may affect cellular architecture and thereby tissue construction and physiology.
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Affiliation(s)
- Harald Herrmann
- Group Functional Architecture of the Cell, German Cancer Research Center, Heidelberg, Germany.
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21
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Easy Method for Keratin 14 Gene Amplification to Exclude Pseudogene Sequences: New Keratin 5 and 14 Mutations in Epidermolysis Bullosa Simplex. J Invest Dermatol 2009; 129:229-31. [PMID: 18704110 DOI: 10.1038/jid.2008.223] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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22
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Yuan H, Liu F, Xiao B, He Y, Liang Y, Liu J. Mutation screening of entirekeratin 5andkeratin 14genes and identification of a novel mutation in a Chinese family with epidermolysis bullosa simplex Dowling-Meara. J Eur Acad Dermatol Venereol 2008; 22:1510-2. [DOI: 10.1111/j.1468-3083.2008.02687.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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23
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Hattori N, Komine M, Kaneko T, Shimazu K, Tsunemi Y, Koizumi M, Goto J, Hashimoto T. A case of epidermolysis bullosa simplex with a newly found missense mutation and polymorphism in the highly conserved helix termination motif among type I keratins, which was previously reported as a pathogenic missense mutation. Br J Dermatol 2006; 155:1062-3. [PMID: 17034543 DOI: 10.1111/j.1365-2133.2006.07425.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- N Hattori
- Department of Dermatology, Fraternity Memorial Hospital, Tokyo, Japan.
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Horiguchi Y, Sawamura D, Mori R, Nakamura H, Takahashi K, Shimizu H. Clinical heterogeneity of 1649delG mutation in the tail domain of keratin 5: a Japanese family with epidermolysis bullosa simplex with mottled pigmentation. J Invest Dermatol 2005; 125:83-5. [PMID: 15982306 DOI: 10.1111/j.0022-202x.2005.23790.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Twenty-five- and 22-y-old Japanese women, who are cousins, presented with distal skin fragility, widespread small, pigmented macules, and toenail deformity. Blisters occurred between the epidermis and the dermis with degeneration of the basal cells, suggesting epidermolysis bullosa simplex with mottled pigmentation (EBS-MP). Electron microscopy of the pigmented spots demonstrated vacuolization of basal cells as well as disturbed junctional structures and incontinence of pigmentation. Gene analysis resulted in detection of a heterozygous deletion of a guanine nucleotide in exon 9 at position 1649. P25L mutation was not detected in either case. It is possible that EBS-MP occurs not only based on the P25L mutation of the keratin 5 molecule, but also because of other types of mutations of epidermal keratin genes.
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Affiliation(s)
- Yuji Horiguchi
- Department of Dermatology, Osaka Red Cross Hospital, Osaka, Japan.
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25
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Li R, Johnson AB, Salomons G, Goldman JE, Naidu S, Quinlan R, Cree B, Ruyle SZ, Banwell B, D'Hooghe M, Siebert JR, Rolf CM, Cox H, Reddy A, Gutiérrez-Solana LG, Collins A, Weller RO, Messing A, van der Knaap MS, Brenner M. Glial fibrillary acidic protein mutations in infantile, juvenile, and adult forms of Alexander disease. Ann Neurol 2005; 57:310-26. [PMID: 15732097 DOI: 10.1002/ana.20406] [Citation(s) in RCA: 175] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Alexander disease is a progressive, usually fatal neurological disorder defined by the widespread and abundant presence in astrocytes of protein aggregates called Rosenthal fibers. The disease most often occurs in infants younger than 2 years and has been labeled a leukodystrophy because of an accompanying severe myelin deficit in the frontal lobes. Later onset forms have also been recognized based on the presence of abundant Rosenthal fibers. In these cases, clinical signs and pathology can be quite different from the infantile form, raising the question whether they share the same underlying cause. Recently, we and others have found pathogenic, de novo missense mutations in the glial fibrillary acidic protein gene in most infantile patients examined and in a few later onset patients. To obtain further information about the role of glial fibrillary acidic protein mutations in Alexander disease, we analyzed 41 new patients and another 3 previously described clinically, including 18 later onset patients. Our results show that dominant missense glial fibrillary acidic protein mutations account for nearly all forms of this disorder. They also significantly expand the catalog of responsible mutations, verify the value of magnetic resonance imaging diagnosis, indicate an unexpected male predominance for the juvenile form, and provide insights into phenotype-genotype relations.
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Affiliation(s)
- Rong Li
- Department of Neurobiology and Civitan International Research Center, University of Alabama-Birmingham, Birmingham, AL, USA
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26
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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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27
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Abstract
Keratins are the type I and II intermediate filament proteins which form a cytoskeletal network within all epithelial cells. They are expressed in pairs in a tissue- and differentiation-specific fashion. Epidermolysis bullosa simplex (EBS) was the first human disorder to be associated with keratin mutations. The abnormal keratin filament aggregates observed in basal cell keratinocytes of some EBS patients are composed of keratins K5 and K14. Dominant mutations in the genes encoding these proteins were shown to disrupt the keratin filament cytoskeleton resulting in cells that are less resilient and blister with mild physical trauma. Identification of mutations in other keratin genes soon followed with attention focussed on disorders showing abnormal clumping of keratin filaments in specific cells. For example, in bullous congenital ichthyosiform erythroderma, clumping of filaments in the suprabasal cells led to the identification of mutations in the suprabasal keratins, K1 and K10. Mutations have now been identified in 18 keratins, all of which produce a fragile cell phenotype. These include ichthyosis bullosa of Siemens (K2e), epidermolytic palmoplantar keratoderma (K1, K9), pachyonychia congenita (K6a, K6b, K16, K17), white sponge nevus (K4, K13), Meesmann's corneal dystrophy (K3, K12), cryptogenic cirrhosis (K8, K18) and monilethrix (hHb6, hHb1).In general, these disorders are inherited as autosomal dominant traits and the mutations act in a dominant-negative manner. Therefore, treatment in the form of gene therapy is difficult, as the mutant gene needs to be inactivated. Ways of achieving this are actively being studied. Reliable mutation detection methods from genomic DNA are now available. This enables rapid screening of patients for keratin mutations. For some of the more severe phenotypes, prenatal diagnosis may be requested and this can now be performed from chorionic villus samples at an early stage of the pregnancy. This review article describes the discovery of, to date, mutations in 18 keratin genes associated with inherited human diseases.
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Affiliation(s)
- Frances Smith
- Epithelial Genetics Group, Human Genetics Unit, University of Dundee, Ninewells Hospital and Medical School, Dundee, UK.
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Wood P, Baty DU, Lane EB, McLean WHI. Long-range polymerase chain reaction for specific full-length amplification of the human keratin 14 gene and novel keratin 14 mutations in epidermolysis bullosa simplex patients. J Invest Dermatol 2003; 120:495-7. [PMID: 12603865 DOI: 10.1046/j.1523-1747.2003.12052.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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29
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Yasukawa K, Sawamura D, McMillan JR, Nakamura H, Shimizu H. Dominant and recessive compound heterozygous mutations in epidermolysis bullosa simplex demonstrate the role of the stutter region in keratin intermediate filament assembly. J Biol Chem 2002; 277:23670-4. [PMID: 11973334 DOI: 10.1074/jbc.m200974200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Keratin intermediate filaments are important cytoskeletal structural proteins involved in maintaining cell shape and function. Mutations in the epidermal keratin genes, keratin 5 or keratin 14 lead to the disruption of keratin filament assembly, resulting in an autosomal dominant inherited blistering skin disease, epidermolysis bullosa simplex (EBS). We investigated a large EBS kindred who exhibited a markedly heterogeneous clinical presentation and detected two distinct keratin 5 mutations in the proband, the most severely affected. One missense mutation (E170K) in the highly conserved helix initiation peptide sequence of the 1A rod domain was found in all the affected family members. In contrast, the other missense mutation (E418K) was found only in the proband. The E418K mutation was located in the stutter region, an interruption in the heptad repeat regularity, whose function as yet remains unclear. We hypothesized that this mutated stutter allele was clinically silent when combined with the wild type allele but aggravates the clinical severity of EBS caused by the E170K mutation on the other allele. To confirm this in vitro, we transfected mutant keratin 5 cDNA into cultured cells. Although only 12.7% of the cells transfected with the E170K mutation alone showed disrupted keratin filament aggregations, significantly more cells (30.0%) cotransfected with both E170K and E418K mutations demonstrated keratin aggregation (p < 0.05). These transfection assay results corresponded to the heterogeneous clinical findings of the EBS patient in this kindred. We have identified the first case of both compound heterozygous dominant (E170K) and recessive (E418K) mutations in any keratin gene and confirmed the significant involvement of the stutter region in the assembly and organization of the keratin intermediate filament network in vitro.
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Affiliation(s)
- Kana Yasukawa
- Department of Dermatology, Hokkaido University Graduate School of Medicine, Kita 15, Nishi 7, Kita-Ku, Sapporo 060-8638, Japan
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30
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Schuilenga-Hut PHL, Scheffer H, Pas HH, Nijenhuis M, Buys CHCM, Jonkman MF. Partial revertant mosaicism of keratin 14 in a patient with recessive epidermolysis bullosa simplex. J Invest Dermatol 2002; 118:626-30. [PMID: 11918708 DOI: 10.1046/j.1523-1747.2002.01715.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A patient with recessive epidermolysis bullosa simplex due to a previously described homozygous KRT14 1842-2A-->C splice-site mutation was re-examined, because we unexpectedly found signs of revertant mosaicism. The germline mutation resulted in different aberrant transcripts containing premature termination codons, all leading to truncated keratin 14 proteins. Basal keratinocytes in skin and in culture completely lacked keratin 14 and intermediate filaments. From this keratin 14-/- patient we started cultures from a new skin biopsy and here, we serendipitously found keratinocytes that spontaneously expressed keratin 14. This biopsy had been taken from an area of skin that was clinically affected, because blisters could simply be evoked by gentle rubbing. Immunofluorescence and electron microscopy of additional biopsies from this skin area revealed a mosaic expression of keratin 14 and reappearance of intermediate filaments in basal keratinocytes. Immunoblotting showed a revertant keratin 14 polypeptide with seemingly normal molecular weight. DNA analysis of exon 2 and its flanking intron borders showed no additional mutations in the genomic KRT14 sequence. Analysis of mRNA isolated from mosaic skin keratinocytes revealed an additional in-frame transcript (1844T-->G, 1845Delta6) that codes for an abnormal keratin 14 polypeptide with a two residue deletion and one amino acid change. The re-expression of a revertant, albeit abnormal, keratin 14 polypeptide, so-called partial revertant mosaicism, accounts for the antibody staining pattern and for the reappearance of intermediate filaments, which however, are semifunctional and not able to revert the clinical phenotype. The combination of a keratin 14-positive and a keratin 14-negative cell population in epidermis as well as in cultured keratinocytes suggests that the cellular reversion might be caused by an endogenous factor. We hypothesize that a second somatic modulating factor in the genome that affects the processing of the mutant KRT14 pre-mRNA may underlie this phenomenon.
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31
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Gu LH, Ichiki Y, Sato M, Kitajima Y. A novel nonsense mutation at E106 of the 2B rod domain of keratin 14 causes dominant epidermolysis bullosa simplex. J Dermatol 2002; 29:136-45. [PMID: 11990248 DOI: 10.1111/j.1346-8138.2002.tb00236.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Epidermolysis bullosa simplex (EBS) is classified into three main types and is caused, in most cases, by missense mutations in the genes encoding keratin (K) 5 and K14. In this study, we clinically, ultrastructurally, immunohistochemically, and molecularly studied a patient with a dominant EBS, Köbner type. Using sequence analysis of genomic DNA, a novel K14 nonsense mutation was identified. A heterozygous mutation G1231T of KRT14 was found to be associated with the disease in the patient. The mutation created a premature stop codon (amino acid codon 411, residue 106 of the 2B helix) in the K14 molecule. This residue lies in a highly conserved region and was recently found to be absolutely required for molecular stability and intermediate filament assembly in K5 and K14. The E411X (E106X) heterozygous ablation, missing the last 16 amino acid residues of the 2B and the entire tail domain of K14, led to disease but did not result in clumping of keratin filaments. It is the first premature stop codon mutation of K14 found in dominant EBS.
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Affiliation(s)
- Li-Hong Gu
- Department of Dermatology, Gifu University, School of Medicine, Japan
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32
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Hesse M, Magin TM, Weber K. Genes for intermediate filament proteins and the draft sequence of the human genome. J Cell Sci 2001; 114:2569-75. [PMID: 11683385 DOI: 10.1242/jcs.114.14.2569] [Citation(s) in RCA: 216] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
We screened the draft sequence of the human genome for genes that encode intermediate filament (IF) proteins in general, and keratins in particular. The draft covers nearly all previously established IF genes including the recent cDNA and gene additions, such as pancreatic keratin 23, synemin and the novel muscle protein syncoilin. In the draft, seven novel type II keratins were identified, presumably expressed in the hair follicle/epidermal appendages. In summary, 65 IF genes were detected, placing IF among the 100 largest gene families in humans. All functional keratin genes map to the two known keratin clusters on chromosomes 12 (type II plus keratin 18) and 17 (type I), whereas other IF genes are not clustered. Of the 208 keratin-related DNA sequences, only 49 reflect true keratin genes, whereas the majority describe inactive gene fragments and processed pseudogenes. Surprisingly, nearly 90% of these inactive genes relate specifically to the genes of keratins 8 and 18. Other keratin genes, as well as those that encode non-keratin IF proteins, lack either gene fragments/pseudogenes or have only a few derivatives. As parasitic derivatives of mature mRNAs, the processed pseudogenes of keratins 8 and 18 have invaded most chromosomes, often at several positions. We describe the limits of our analysis and discuss the striking unevenness of pseudogene derivation in the IF multigene family. Finally, we propose to extend the nomenclature of Moll and colleagues to any novel keratin.
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Affiliation(s)
- M Hesse
- Institute of Genetics, Division of Molecular Genetics and Bonner Forum Biomedizin, University of Bonn, Germany.
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33
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Nickerson ML, Warren MB, Zbar B, Schmidt LS. Random mutagenesis-PCR to introduce alterations into defined DNA sequences for validation of SNP and mutation detection methods. Hum Mutat 2001; 17:210-9. [PMID: 11241843 DOI: 10.1002/humu.6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Sensitive and high throughput techniques are required for the detection of DNA sequence variants such as single nucleotide polymorphisms (SNPs) and mutations. One problem, common to all methods of SNP and mutation detection, is that experimental conditions required for detection of DNA sequence variants depend on the specific DNA sequence to be analyzed. Although algorithms and other calculations have been developed to predict the experimental conditions required to detect DNA sequence variation in a specific DNA sequence, these algorithms do not always provide reliable information and experimental conditions for SNP and mutation detection must be devised empirically. Determination of experimental conditions for detection of DNA sequence variation is difficult when samples containing only wild type sequence are available. When patient derived positive controls are used, increasingly there are valid concerns about commercial ownership and patient privacy. This report presents a rapid and efficient method, employing random mutagenesis-PCR (RM-PCR) using low fidelity DNA polymerase, to randomly introduce single and multiple base substitutions and deletions into DNA sequences of interest. Clones with sequence changes were used to validate denaturing HPLC (DHPLC) algorithm predictions, optimize conditions for mutation detection in exon 15 of the tyrosine kinase domain of the MET proto-oncogene, and to confirm the association between specific DNA sequence changes and unique DHPLC chromatographic profiles (signatures). Finally, DNA from 33 papillary renal carcinoma (PRC) patients was screened for mutations in exon 15 of MET using "validated" DHPLC conditions as a proof of principle application of RM-PCR. Use of RM-PCR for DHPLC and other SNP/mutation detection methods is discussed along with challenges associated with detecting sequence alterations in mixed tumor/normal tissue, pooled samples, and from regions of the genome that have been amplified during tumorigenesis or duplicated during evolution. Hum Mutat 17:210-219, 2001. Published 2001 Wiley-Liss, Inc.
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Affiliation(s)
- M L Nickerson
- Laboratory of Immunobiology, National Cancer Institute-Frederick Cancer Research and Development Center, Frederick, Maryland, USA.
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