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Robinaj Eady - One of the best experts on this subject based on the ideXlab platform.
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frameshift mutation in the v2 domain of human Keratin 1 results in striate palmoplantar keratoderma
Journal of Investigative Dermatology, 2002Co-Authors: Neilv Whittock, Robinaj Eady, Patriciajc Doppinghepenstal, Frances J D Smith, W Irwin H Mclean, Hong Wan, R Mallipeddi, Andrew W D Griffiths, Gabrielle H S Ashton, John A McgrathAbstract:The striate form of palmoplantar keratoderma is a rare autosomal dominant disorder affecting palm and sole skin. Genetic heterogeneity of striate palmoplantar keratoderma has been demonstrated with pathogenic mutations in the desmosomal proteins desmoplakin and desmoglein 1. We have studied a four-generation family of British descent with striate palmoplantar keratoderma. Ultrastructural studies show that intermediate filaments of suprabasal Keratinocytes are finer than those of the basal layer. In addition, desmosome numbers are normal, but their inner plaques and midline structures are attenuated. Microsatellite markers were used to screen candidate loci including the epidermal differentiation complex on 1q, the desmoplakin locus on 6p, the type I and II Keratin gene clusters on chromosomes 12q and 17q, and the desmosomal cadherin gene cluster on chromosome 18q. Significant genetic linkage to chromosome 12q was observed using marker D12S368, with a maximum two-point lod score of 3.496 at a recombination fraction of 0. Direct sequencing of the Keratin 1 gene revealed a frameshift mutation in exon 9 that leads to the partial loss of the glycine loop motif in the V2 domain and the gain of a novel 70 amino acid peptide. Using expression studies we show that the V2 domain is essential for normal function of Keratin intermediate filaments.
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new mutations in Keratin 1 that cause bullous congenital ichthyosiform erythroderma and Keratin 2e that cause ichthyosis bullosa of siemens
British Journal of Dermatology, 2001Co-Authors: Neilv Whittock, W A D Griffiths, G H S Ashton, Robinaj EadyAbstract:The intermediate filaments of epithelial cells are formed by Keratins, a family of structurally related proteins, which are expressed in pairs of acidic (type I) and basic (type II) polypeptides in a tissue- and differentiation-specific manner. Mutations in the genes encoding several Keratins have been implicated in the pathogenesis of diseases of Keratinization. We report molecular analysis of two patients with the rare autosomal dominant disorders bullous congenital ichthyosiform erythroderma (BCIE) and ichthyosis bullosa of Siemens (IBS). Previous studies have shown that these genodermatoses are due to mutations in the KRT1 and KRT2E genes, respectively. We report a new amino acid substitution mutation in codon 155 of KRT1 (valine to aspartic acid) in the conserved H1 domain of the protein in the patient with BCIE. We also report a novel amino acid substitution mutation in codon 192 of KRT2E (asparagine to lysine) in the conserved 1A helix initiation peptide of the protein in the patient with IBS. Our results demonstrate that these mutations are deleterious to Keratin filament network stability and lead to specific clinical inherited disorders of Keratinization.
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novel splice site mutation in Keratin 1 underlies mild epidermolytic palmoplantar keratoderma in three kindreds
Journal of Investigative Dermatology, 2001Co-Authors: Sarah J Hatsell, I M Leigh, Robinaj Eady, Patriciajc Doppinghepenstal, Lena Wennerstrand, Colin S Munro, David P KelsellAbstract:We report a novel mutation in the exon 6 splice donor site of Keratin 1 (G4134A) that segregates with a palmoplantar keratoderma in three kindreds. The nucleotide substitution leads to the utilization of a novel in-frame splice site 54 bases downstream of the mutation with the subsequent insertion of 18 amino acids into the 2B rod domain. This mutation appears to have a milder effect than previously described mutations in the helix initiation and termination sequence on the function of the rod domain, with regard to filament assembly and stability. Affected individuals displayed only mild focal epidermolysis in the spinous layer of palmoplantar epidermis, in comparison with cases of bullous congenital ichthyosiform erythroderma also due to Keratin 1 mutations, which show widespread and severe epidermolysis. This study describes a novel mutation in KRT1 that results in a phenotype distinct from classical bullous congenital ichthyosiform erythroderma.
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Genomic organization and amplification of the human epidermal type II Keratin genes K1 and K5
Biochemical and biophysical research communications, 2000Co-Authors: Neilv Whittock, Robinaj EadyAbstract:Abstract Keratins are a family of structurally related proteins that form the intermediate filament cytoskeleton in epithelial cells. Mutations in K1 and K5 result in the autosomal dominant disorders epidermolytic hyperkeratosis/bullous congenital ichthyosiform erythroderma and epidermolysis bullosa simplex, respectively. Most disease-associated mutations are within exons encoding protein domains involved in Keratin filament assembly. However, some mutations occur outside the mutation hot-spots and may perturb intermolecular interactions between Keratins and other proteins, usually with milder clinical consequences. To screen the entire Keratin 1 and Keratin 5 genes we have characterized their intron–exon organization. The Keratin 1 gene comprises 9 exons spanning approximately 5.6 kb on 12q, and the Keratin 5 gene comprises 9 exons spanning approximately 6.1 kb on 12q. We have also developed a comprehensive PCR-based mutation detection strategy using primers placed on flanking introns followed by direct sequencing of the PCR products.
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mutations in the rod 1a domain of Keratins 1 and 10 in bullous congenital ichthyosiform erythroderma bcie
Journal of Investigative Dermatology, 1994Co-Authors: W Irwin H Mclean, I M Leigh, Robinaj Eady, Patriciajc Doppinghepenstal, Caroline Higgins, James R Mcmillan, Harshad Navsaria, J I Harper, D Paige, S.m. MorleyAbstract:Bullous congenital ichthyosiform erythroderma is a human hereditary skin disorder in which suprabasal Keratinocytes rupture. Recent reports have implicated Keratins K1 and K10 in this disease. Here we describe four diverse Keratin mutations that are all significantly associated with this disease. Two of these are in the helix 1A subdomain of the type II Keratin 1, giving a serine-to-proline substitution in codon 185 and an asparagine-to-serine substitution in codon 187. In the analogous region of type I Keratin 10, an arginine-to-proline and an arginine-to-serine transition in codon 156 have been identified. All four mutations create restriction fragment length polymorphisms that were used exclude the mutations from 120 normal chromosomes. Insertional polymorphism (in the V2 subdomains of the non-helical tails of K1 and K10) was excluded as the cause of the phenotypic heterogeneity observed within one family.
John G. Compton - One of the best experts on this subject based on the ideXlab platform.
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two cases of primarily palmoplantar keratoderma associated with novel mutations in Keratin 1
Journal of Investigative Dermatology, 2002Co-Authors: Amy S Paller, Alan D Irvine, W Irwin H Mclean, Ana Terronkwiatkowski, David J Atherton, John G. ComptonAbstract:Mutations in Keratin 1 were initially described in the classical form of bullous congenital ichthyosiform erythroderma (also known as epidermolytic hyperkeratosis). More recently the range of phenotypes associated with mutations in this gene has been extended to include annular ichthyosiform erythroderma and mild epidermolytic palmoplantar keratoderma. Here we present two novel mutations in the Keratin 1 gene (KRT1) : a 5′ donor splice site mutation in exon 1 (591 + 2T > A) that predicts a 22 amino acid in-frame deletion in the Keratin 1 1A domain; and an in-frame deletion in exon 7 (1376del24) that predicts a foreshortened 2B coiled-coil domain of Keratin 1. In each case these mutations are associated with palmoplantar keratoderma and mild ichthyosis, largely limited to the flexural areas. These mutations appear to have a less damaging effect than previously reported mis-sense mutations sited in the helix boundary motifs. This report extends the range of phenotypes associated with mutations in KRT1 .
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a highly conserved lysine residue on the head domain of type ii Keratins is essential for the attachment of Keratin intermediate filaments to the cornified cell envelope through isopeptide crosslinking by transglutaminases
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Eleonora Candi, J J Digiovanna, John G. Compton, Lyuben N. Marekov, Peter M Elias, Edit Tarcsa, Peter M. SteinertAbstract:We have addressed the question of how Keratin intermediate filaments are associated with the cell envelope at the periphery of cornified epidermal cells. Many peptides from human epidermal cell envelopes containing isopeptide crosslinks inserted by transglutaminases in vivo have been characterized. A major subset involves the type II Keratin chains Keratin 1, 2e, 5, or 6 crosslinked to several protein partners through a lysine residue located in a conserved region of the V1 subdomain of their head domains. This sequence specificity was confirmed in in vitro crosslinking experiments. Previously the causative mutation in a family with diffuse nonepidermolytic palmar-plantar keratoderma was shown to be the loss in one allele of the same lysine residue of the Keratin 1 chain. Ultrastructural studies of affected palm epidermis have revealed abnormalities in the organization of Keratin filaments subjacent to the cell envelope and in the shape of the cornified cells. Together, these data suggest a mechanism for the coordination of cornified cell structure by permanent covalent attachment of the Keratin intermediate filament cytoskeleton to the cell envelope by transglutaminase crosslinking. Furthermore, these studies identify the essential role of a conserved lysine residue on the head domains of type II Keratins in the supramolecular organization of Keratin filaments in cells.
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a mutation in the v1 end domain of Keratin 1 in non epidermolytic palmar plantar keratoderma
Journal of Investigative Dermatology, 1994Co-Authors: Virginia Kimonis, Jun-mo Yang, S J Bale, J J Digiovanna, Sharon Z Doyle, John G. ComptonAbstract:Mutations in Keratin 9 have been found in families with an epidermolytic form of palmar-plantar keratoderma (PPK). In another form of PPK (Unna-Thost type), epidermolysis is not observed histologically. We studied a pedigree with this non-epidermolytic form of PPK. By gene linkage analysis, the type I Keratin locus could be excluded but complete linkage with the type II Keratin region was found. Sequence analysis identified a single base change in the amino-terminal V1 variable subdomain of Keratin 1, which caused a lysine to isoleucine substitution. This non-conservative mutation completely cosegregated with the disease and was not observed in 50 unrelated unaffected individuals. An examination of Keratin amino-terminal sequences revealed a previously unreported 22-residue window in the V1 subdomain that is conserved among most type II Keratins. The altered lysine is an invariant residue in this conserved sequence. Previously described Keratin mutations affect the central regions important for filament assembly and stability, and cause diseases characterized by cellular degeneration or disruption. This is the first disease mutation in a Keratin chain variable end region. The observation that it is not associated with epidermolysis supports the concept that the amino-terminal domain of Keratins may be involved in supramolecular interactions of Keratin filaments rather than stability. Therefore, hyperkeratosis associated with this mutation may be due to perturbations in the interactions of the Keratin end domain with other cellular components.
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preferential sites in Keratin 10 that are mutated in epidermolytic hyperkeratosis
American Journal of Human Genetics, 1994Co-Authors: Constantin C. Chipev, Jun-mo Yang, J J Digiovanna, John G. Compton, Peter M. Steinert, Lyuben N. Marekov, S J BaleAbstract:Epidermolytic hyperkeratosis (EH) is a rare autosomal dominant skin disease. Recent studies in the authors' laboratory established genetic linkage to the type II Keratin gene locus on chromosome 12q in one family with EH and identified a single amino acid mutation in Keratin 1 that is responsible for the disease. Other point mutations in the Keratin 1 or Keratin 10 genes have now been reported in other patients with EH. The authors have examined a series of probands with EH in order to develop a catalog of mutations in Keratin 10. Using direct sequencing of PCR-amplified genomic DNA, they have identified mutations in six families, in which five mutations occur in the beginning of the 1A rod domain of Keratin 10-namely, two Arg10 to His, one Arg10 to Cys, and Asn8 to His, and a Tyr14 to Asp. This region contains highly conserved residues among all Keratins. An additional mutation (Leu103 to Gln) was found in the conserved region late in the 2B rod domain in Keratin 10. The authors developed several allele-specific assays to assess the frequency of these mutations in the general population. No evidence was found for the presence of such changes in unaffected individuals. In vitromore » functional assays performed with peptides corresponding to the 1A mutations in these families show severely diminished capacity to disaggregate preformed Keratin intermediate filaments, in comparison with a wild-type control peptide. Results from this work support the hypothesis that the beginning of the 1A rod domain segment in Keratin 10 contains preferential sites for disease-causing mutation in EH. This should be of considerable use when developing prenatal diagnostic tests and biologically based therapies for this disease. 29 refs., 6 figs., 2 tabs.« less
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Mutations in the H1 and 1A Domains in the Keratin 1 Gene in Epidermolytic Hyperkeratosis
Journal of Investigative Dermatology, 1994Co-Authors: Constantin C. Chipev, S J Bale, J J Digiovanna, Peter M. Steinert, Lyuben N. Marekov, John G. ComptonAbstract:In the autosomal dominant disorder epidermolytic hyperkeratosis, the structural integrity of the Keratin intermediate filaments is altered in the suprabasal layers of the epidermis. We and others have used genetic linkage studies and mutation analysis to establish that single amino acid substitutions in either the Keratin 1 or Keratin 10 chains can cause epidermolytic hyperkeratosis. However, a larger database of mutations is required to better understand the relationship between specific mutations in these Keratin chains and their effect on Keratin filament structure. A larger database will also provide a catalog that may be useful for genetic counseling purposes. In this paper, we report the identification of three new mutations of the Keratin 1 chain of epidermolytic hyperkeratosis probands in highly conserved residues in the H1 or beginning of the 1A rod domain segments. These correspond to regions involved in molecular overlaps between neighboring molecules in Keratin filaments. Using an in vitro assay, synthetic peptides bearing these substitutions show diminished capacity to disassemble preformed filaments in vitro in comparison to the wild type peptides. Moreover, analyses of all mutations in epidermolytic hyperkeratosis known to date demonstrate remarkable clustering in the molecular overlap region. We conclude that non-conservative substitutions in the overlap region are likely to interfere with normal Keratin filament structure and function, leading to pathology.
W Irwin H Mclean - One of the best experts on this subject based on the ideXlab platform.
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two cases of primarily palmoplantar keratoderma associated with novel mutations in Keratin 1
Journal of Investigative Dermatology, 2002Co-Authors: Amy S Paller, Alan D Irvine, W Irwin H Mclean, Ana Terronkwiatkowski, David J Atherton, John G. ComptonAbstract:Mutations in Keratin 1 were initially described in the classical form of bullous congenital ichthyosiform erythroderma (also known as epidermolytic hyperkeratosis). More recently the range of phenotypes associated with mutations in this gene has been extended to include annular ichthyosiform erythroderma and mild epidermolytic palmoplantar keratoderma. Here we present two novel mutations in the Keratin 1 gene (KRT1) : a 5′ donor splice site mutation in exon 1 (591 + 2T > A) that predicts a 22 amino acid in-frame deletion in the Keratin 1 1A domain; and an in-frame deletion in exon 7 (1376del24) that predicts a foreshortened 2B coiled-coil domain of Keratin 1. In each case these mutations are associated with palmoplantar keratoderma and mild ichthyosis, largely limited to the flexural areas. These mutations appear to have a less damaging effect than previously reported mis-sense mutations sited in the helix boundary motifs. This report extends the range of phenotypes associated with mutations in KRT1 .
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frameshift mutation in the v2 domain of human Keratin 1 results in striate palmoplantar keratoderma
Journal of Investigative Dermatology, 2002Co-Authors: Neilv Whittock, Robinaj Eady, Patriciajc Doppinghepenstal, Frances J D Smith, W Irwin H Mclean, Hong Wan, R Mallipeddi, Andrew W D Griffiths, Gabrielle H S Ashton, John A McgrathAbstract:The striate form of palmoplantar keratoderma is a rare autosomal dominant disorder affecting palm and sole skin. Genetic heterogeneity of striate palmoplantar keratoderma has been demonstrated with pathogenic mutations in the desmosomal proteins desmoplakin and desmoglein 1. We have studied a four-generation family of British descent with striate palmoplantar keratoderma. Ultrastructural studies show that intermediate filaments of suprabasal Keratinocytes are finer than those of the basal layer. In addition, desmosome numbers are normal, but their inner plaques and midline structures are attenuated. Microsatellite markers were used to screen candidate loci including the epidermal differentiation complex on 1q, the desmoplakin locus on 6p, the type I and II Keratin gene clusters on chromosomes 12q and 17q, and the desmosomal cadherin gene cluster on chromosome 18q. Significant genetic linkage to chromosome 12q was observed using marker D12S368, with a maximum two-point lod score of 3.496 at a recombination fraction of 0. Direct sequencing of the Keratin 1 gene revealed a frameshift mutation in exon 9 that leads to the partial loss of the glycine loop motif in the V2 domain and the gain of a novel 70 amino acid peptide. Using expression studies we show that the V2 domain is essential for normal function of Keratin intermediate filaments.
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an atypical form of bullous congenital ichthyosiform erythroderma is caused by a mutation in the l12 linker region of Keratin 1
Journal of Investigative Dermatology, 1998Co-Authors: H Kremer, Edwin C M Mariman, A P M Lavrijsen, W Irwin H Mclean, Birgitte E Lane, Diana Melchers, Dirk J Ruiter, Peter M SteijlenAbstract:Defective Keratins are the cause of a number of hereditary disorders of the epidermis and other epithelia. The disease-causing mutations in Keratins are clustered in the rod domain, and mutations in the helix boundary peptides cause the most severe forms of epidermal fragility syndromes. Siemens described a family with an atypical, mild form of bullous congenital ichthyosiform erythroderma. Linkage analysis in this family indicated that a defective type II Keratin might be the underlying cause, Keratins K1 and K2e being the best candidates. A substitution of valine for aspartic acid was detected at position 340 (D340V) in the L12 region of the K1 polypeptide. The mutation was found to cosegregate with the disorder in the family. Herewith, a genotype-phenotype correlation is shown for bullous congenital ichthyosiform erythroderma comparable with that described for epidermolysis bullosa simplex.
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mutations in the rod 1a domain of Keratins 1 and 10 in bullous congenital ichthyosiform erythroderma bcie
Journal of Investigative Dermatology, 1994Co-Authors: W Irwin H Mclean, I M Leigh, Robinaj Eady, Patriciajc Doppinghepenstal, Caroline Higgins, James R Mcmillan, Harshad Navsaria, J I Harper, D Paige, S.m. MorleyAbstract:Bullous congenital ichthyosiform erythroderma is a human hereditary skin disorder in which suprabasal Keratinocytes rupture. Recent reports have implicated Keratins K1 and K10 in this disease. Here we describe four diverse Keratin mutations that are all significantly associated with this disease. Two of these are in the helix 1A subdomain of the type II Keratin 1, giving a serine-to-proline substitution in codon 185 and an asparagine-to-serine substitution in codon 187. In the analogous region of type I Keratin 10, an arginine-to-proline and an arginine-to-serine transition in codon 156 have been identified. All four mutations create restriction fragment length polymorphisms that were used exclude the mutations from 120 normal chromosomes. Insertional polymorphism (in the V2 subdomains of the non-helical tails of K1 and K10) was excluded as the cause of the phenotypic heterogeneity observed within one family.
Peter M. Steinert - One of the best experts on this subject based on the ideXlab platform.
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a novel glutamic acid to aspartic acid mutation near the end of the 2b rod domain in the Keratin 1 chain in epidermolytic hyperkeratosis
Journal of Investigative Dermatology, 1999Co-Authors: Jummo Yang, Kiebang Nam, Hyongcheol Kim, Jeunghoon Lee, Jangku Park, Eilsoo Lee, Peter M. SteinertAbstract:We report a mutation in a mild case of epidermolytic hyperkeratosis that results in a glutamic acid to aspartic acid substitution in a novel location, codon 477 or position 106 of the 2B rod domain of the Keratin 1 chain. This residue has been conserved in all intermediate filament chains and lies near the beginning of the highly conserved helix termination sequence and just prior to the predicted molecular overlap region. Keratin filaments assembled in vitro from chains bearing this substitution are abnormal, indicating that the glutamic acid residue is critically involved in ionic interactions in intermediate levels of filament structure.
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a highly conserved lysine residue on the head domain of type ii Keratins is essential for the attachment of Keratin intermediate filaments to the cornified cell envelope through isopeptide crosslinking by transglutaminases
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Eleonora Candi, J J Digiovanna, John G. Compton, Lyuben N. Marekov, Peter M Elias, Edit Tarcsa, Peter M. SteinertAbstract:We have addressed the question of how Keratin intermediate filaments are associated with the cell envelope at the periphery of cornified epidermal cells. Many peptides from human epidermal cell envelopes containing isopeptide crosslinks inserted by transglutaminases in vivo have been characterized. A major subset involves the type II Keratin chains Keratin 1, 2e, 5, or 6 crosslinked to several protein partners through a lysine residue located in a conserved region of the V1 subdomain of their head domains. This sequence specificity was confirmed in in vitro crosslinking experiments. Previously the causative mutation in a family with diffuse nonepidermolytic palmar-plantar keratoderma was shown to be the loss in one allele of the same lysine residue of the Keratin 1 chain. Ultrastructural studies of affected palm epidermis have revealed abnormalities in the organization of Keratin filaments subjacent to the cell envelope and in the shape of the cornified cells. Together, these data suggest a mechanism for the coordination of cornified cell structure by permanent covalent attachment of the Keratin intermediate filament cytoskeleton to the cell envelope by transglutaminase crosslinking. Furthermore, these studies identify the essential role of a conserved lysine residue on the head domains of type II Keratins in the supramolecular organization of Keratin filaments in cells.
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preferential sites in Keratin 10 that are mutated in epidermolytic hyperkeratosis
American Journal of Human Genetics, 1994Co-Authors: Constantin C. Chipev, Jun-mo Yang, J J Digiovanna, John G. Compton, Peter M. Steinert, Lyuben N. Marekov, S J BaleAbstract:Epidermolytic hyperkeratosis (EH) is a rare autosomal dominant skin disease. Recent studies in the authors' laboratory established genetic linkage to the type II Keratin gene locus on chromosome 12q in one family with EH and identified a single amino acid mutation in Keratin 1 that is responsible for the disease. Other point mutations in the Keratin 1 or Keratin 10 genes have now been reported in other patients with EH. The authors have examined a series of probands with EH in order to develop a catalog of mutations in Keratin 10. Using direct sequencing of PCR-amplified genomic DNA, they have identified mutations in six families, in which five mutations occur in the beginning of the 1A rod domain of Keratin 10-namely, two Arg10 to His, one Arg10 to Cys, and Asn8 to His, and a Tyr14 to Asp. This region contains highly conserved residues among all Keratins. An additional mutation (Leu103 to Gln) was found in the conserved region late in the 2B rod domain in Keratin 10. The authors developed several allele-specific assays to assess the frequency of these mutations in the general population. No evidence was found for the presence of such changes in unaffected individuals. In vitromore » functional assays performed with peptides corresponding to the 1A mutations in these families show severely diminished capacity to disaggregate preformed Keratin intermediate filaments, in comparison with a wild-type control peptide. Results from this work support the hypothesis that the beginning of the 1A rod domain segment in Keratin 10 contains preferential sites for disease-causing mutation in EH. This should be of considerable use when developing prenatal diagnostic tests and biologically based therapies for this disease. 29 refs., 6 figs., 2 tabs.« less
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Mutations in the H1 and 1A Domains in the Keratin 1 Gene in Epidermolytic Hyperkeratosis
Journal of Investigative Dermatology, 1994Co-Authors: Constantin C. Chipev, S J Bale, J J Digiovanna, Peter M. Steinert, Lyuben N. Marekov, John G. ComptonAbstract:In the autosomal dominant disorder epidermolytic hyperkeratosis, the structural integrity of the Keratin intermediate filaments is altered in the suprabasal layers of the epidermis. We and others have used genetic linkage studies and mutation analysis to establish that single amino acid substitutions in either the Keratin 1 or Keratin 10 chains can cause epidermolytic hyperkeratosis. However, a larger database of mutations is required to better understand the relationship between specific mutations in these Keratin chains and their effect on Keratin filament structure. A larger database will also provide a catalog that may be useful for genetic counseling purposes. In this paper, we report the identification of three new mutations of the Keratin 1 chain of epidermolytic hyperkeratosis probands in highly conserved residues in the H1 or beginning of the 1A rod domain segments. These correspond to regions involved in molecular overlaps between neighboring molecules in Keratin filaments. Using an in vitro assay, synthetic peptides bearing these substitutions show diminished capacity to disassemble preformed filaments in vitro in comparison to the wild type peptides. Moreover, analyses of all mutations in epidermolytic hyperkeratosis known to date demonstrate remarkable clustering in the molecular overlap region. We conclude that non-conservative substitutions in the overlap region are likely to interfere with normal Keratin filament structure and function, leading to pathology.
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the conserved h1 domain of the type ii Keratin 1 chain plays an essential role in the alignment of nearest neighbor molecules in mouse and human Keratin 1 Keratin 10 intermediate filaments at the two to four molecule level of structure
Journal of Biological Chemistry, 1993Co-Authors: Peter M. Steinert, D A D ParryAbstract:Abstract A number of fundamental questions pertaining to the registration and packing of the constituent coiled-coil molecules in Keratin intermediate filaments, and to the regions of the sequences that are responsible for these levels of organization, remain to be elucidated. In this study, small assembly-competent oligomers of mouse and human Keratin 1/Keratin 10 Keratin filaments were cross-linked by the formation of disulfide bonds catalyzed by the copper-phenanthroline reaction. By isolation and characterization of cross-linked peptides, it has been possible to establish two major modes of molecule alignment: an antiparallel arrangement of half-staggered molecules with their 2B segments overlapping and an antiparallel arrangement of molecules in close axial registration. These data confirm earlier models based on theoretical considerations (Crewther, W. G., Dowling, L. M., Steinert, P. M., and Parry, D. A. D. (1983) Int. J. Biol. Macromol. 5, 267-274). Interestingly, these models place the conserved H1 and H2 end domain segments, which flank the ends of the rod domains of the type II Keratin 1 chain, in alignment with either the ends of the rod domains and/or with the L2 segment near the center of the rod domains, of the nearest neighbor molecules. Competition experiments with synthetic peptides suggest that the conserved H1 (and possibly H2) subdomain sequences unique to type II Keratin chains play pivotal roles in the registration of neighboring molecules in Keratin filaments. The data thus afford a molecular explanation for why Keratin filaments require a type II chain for assembly in vivo and in vitro.
Neilv Whittock - One of the best experts on this subject based on the ideXlab platform.
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frameshift mutation in the v2 domain of human Keratin 1 results in striate palmoplantar keratoderma
Journal of Investigative Dermatology, 2002Co-Authors: Neilv Whittock, Robinaj Eady, Patriciajc Doppinghepenstal, Frances J D Smith, W Irwin H Mclean, Hong Wan, R Mallipeddi, Andrew W D Griffiths, Gabrielle H S Ashton, John A McgrathAbstract:The striate form of palmoplantar keratoderma is a rare autosomal dominant disorder affecting palm and sole skin. Genetic heterogeneity of striate palmoplantar keratoderma has been demonstrated with pathogenic mutations in the desmosomal proteins desmoplakin and desmoglein 1. We have studied a four-generation family of British descent with striate palmoplantar keratoderma. Ultrastructural studies show that intermediate filaments of suprabasal Keratinocytes are finer than those of the basal layer. In addition, desmosome numbers are normal, but their inner plaques and midline structures are attenuated. Microsatellite markers were used to screen candidate loci including the epidermal differentiation complex on 1q, the desmoplakin locus on 6p, the type I and II Keratin gene clusters on chromosomes 12q and 17q, and the desmosomal cadherin gene cluster on chromosome 18q. Significant genetic linkage to chromosome 12q was observed using marker D12S368, with a maximum two-point lod score of 3.496 at a recombination fraction of 0. Direct sequencing of the Keratin 1 gene revealed a frameshift mutation in exon 9 that leads to the partial loss of the glycine loop motif in the V2 domain and the gain of a novel 70 amino acid peptide. Using expression studies we show that the V2 domain is essential for normal function of Keratin intermediate filaments.
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new mutations in Keratin 1 that cause bullous congenital ichthyosiform erythroderma and Keratin 2e that cause ichthyosis bullosa of siemens
British Journal of Dermatology, 2001Co-Authors: Neilv Whittock, W A D Griffiths, G H S Ashton, Robinaj EadyAbstract:The intermediate filaments of epithelial cells are formed by Keratins, a family of structurally related proteins, which are expressed in pairs of acidic (type I) and basic (type II) polypeptides in a tissue- and differentiation-specific manner. Mutations in the genes encoding several Keratins have been implicated in the pathogenesis of diseases of Keratinization. We report molecular analysis of two patients with the rare autosomal dominant disorders bullous congenital ichthyosiform erythroderma (BCIE) and ichthyosis bullosa of Siemens (IBS). Previous studies have shown that these genodermatoses are due to mutations in the KRT1 and KRT2E genes, respectively. We report a new amino acid substitution mutation in codon 155 of KRT1 (valine to aspartic acid) in the conserved H1 domain of the protein in the patient with BCIE. We also report a novel amino acid substitution mutation in codon 192 of KRT2E (asparagine to lysine) in the conserved 1A helix initiation peptide of the protein in the patient with IBS. Our results demonstrate that these mutations are deleterious to Keratin filament network stability and lead to specific clinical inherited disorders of Keratinization.
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Genomic organization and amplification of the human epidermal type II Keratin genes K1 and K5
Biochemical and biophysical research communications, 2000Co-Authors: Neilv Whittock, Robinaj EadyAbstract:Abstract Keratins are a family of structurally related proteins that form the intermediate filament cytoskeleton in epithelial cells. Mutations in K1 and K5 result in the autosomal dominant disorders epidermolytic hyperkeratosis/bullous congenital ichthyosiform erythroderma and epidermolysis bullosa simplex, respectively. Most disease-associated mutations are within exons encoding protein domains involved in Keratin filament assembly. However, some mutations occur outside the mutation hot-spots and may perturb intermolecular interactions between Keratins and other proteins, usually with milder clinical consequences. To screen the entire Keratin 1 and Keratin 5 genes we have characterized their intron–exon organization. The Keratin 1 gene comprises 9 exons spanning approximately 5.6 kb on 12q, and the Keratin 5 gene comprises 9 exons spanning approximately 6.1 kb on 12q. We have also developed a comprehensive PCR-based mutation detection strategy using primers placed on flanking introns followed by direct sequencing of the PCR products.
