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Keratin
Kinds of Keratin Terms modified by Keratin Selected AbstractsKeratin 9 gene mutations in five Korean families with epidermolytic palmoplantar keratodermaEXPERIMENTAL DERMATOLOGY, Issue 6 2003Joo-Heung Lee Abstract:, Epidermolytic palmoplantar keratoderma (EPPK) is an autosomal dominant disease characterized clinically by localized palmoplantar thickening and histopathologically by granular degeneration of the epidermis. Recent molecular biological studies have revealed that EPPK is caused by mutations of the keratin 9 gene in sequences mainly encoding the highly conserved 1 A rod domain. Here we demonstrate a novel mutation of N160H (position 8 of the 1 A domain) and two other previously reported mutations, R162W and N160S, in five unrelated Korean families with EPPK. The three-dimensional structure of the 1 A domain of the related vimentin intermediate filament protein chain is now known. Based on its likely similarity to the keratin 9 chain, we predict that inappropriate amino acid substitutions in position 10 of 1 A will likely interfere with coiled-coil dimer stability, and those in position 8 will interfere with tetramer stability. Accordingly, these mutations compromise the structural integrity of the keratin intermediate filaments leading to the pathology of EPPK. [source] Stratum corneum keratin structure, function and formation , a comprehensive reviewINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 6 2006L. Norlén Synopsis A comprehensive review on stratum corneum keratin organization, largely based on the recently published cubic rod-packing and membrane templating model [J. Invest. Dermatol., 123, 2004, 715], is presented. Keratin is the major non-aqueous component (wt/wt) of stratum corneum. As 90,100% of the stratum corneum water is thought to be located intracellularly one may presume that keratin also is a major factor (together with filaggrin-derived free amino acids) determining stratum corneum hydration level and water holding capacity. This water holding capacity depends in turn on the structural organization of the corneocyte keratin intermediate filament network. The cubic rod-packing model for the structure and function of the stratum corneum cell matrix postulates that corneocyte keratin filaments are arranged according to a cubic-like rod-packing symmetry. It is in accordance with the cryo-electron density pattern of the native corneocyte keratin matrix and could account for the swelling behaviour and the mechanical properties of mammalian stratum corneum. The membrane templating model for keratin dynamics and for the formation of the stratum corneum cell matrix postulates the presence in viable epidermal cellular space of a highly dynamic small lattice parameter (<30 nm) membrane structure with cubic-like symmetry, to which keratin is associated. It further proposes that membrane templating, rather than spontaneous self-assembly, is responsible for keratin intermediate filament formation and dynamics. It is in accordance with the cryo-electron density patterns of the native keratinocyte cytoplasmic space and could account for the characteristic features of the keratin network formation process, the dynamic properties of keratin intermediate filaments, the close lipid association of keratin, the insolubility in non-denaturating buffers and pronounced polymorphism of keratin assembled in vitro, and the measured reduction in cell-volume and hydration level between stratum granulosum and stratum corneum. Résumé, La kératine est le composant majeur anhydre de la couche cornée. Etant donné que l'on considère que 90 à 100% de l'eau de la couche cornée est localisée à l'intérieur des cellules, on peut penser que la kératine joue également un rôle important (en association avec les acides aminés libres dérivés de la filagrine) dans le niveau d'hydratation de la couche cornée et sa capacité de rétention de l'eau. Cette capacité de rétention de l'eau dépend elle-même de l'organization structurelle du réseau de filaments intermédiaires de la kératine des cornéocytes. Le modèle de cylindre en réseau cubique appliquéà la structure et aux fonctions de la matrice des cellules de la couche cornée stipule que les filaments de la kératine des cornéocytes sont disposés symétriquement, les paquets de fibrilles formant une structure cubique. Ceci est conforme au modèle de densité cryo-électronique de la matrice kératinique des cornéocytes natifs et pourrait expliquer le comportement de gonflement et les propriétés mécaniques de la couche cornée des mammifères. Le modèle d'assemblage membranaire appliquéà la dynamique de la kératine et à la formation de la matrice cellulaire du stratum cornéum postule la présence dans l'espace cellulaire viable de l'épiderme d'une structure membranaire hautement dynamique présentant un petit paramètre de maille (<30 nm) et une organization en forme de cube, à laquelle la kératine est associée. D'autre part, ce modèle suggère qu'un assemblage membranaire plutôt qu'un auto-assemblage spontané puisse être à l'origine de la formation des filaments intermédiaires de kératine et de leur dynamique. Ceci concorde avec les modèles de densité cryo-électronique du cytoplasme des kératinocytes natifs et pourrait expliquer les caractéristiques du processus de formation du réseau kératinique, les propriétés dynamiques des filaments intermédiaires de kératine, l'association de la kératine avec les lipides, l'insolubilité dans les tampons non dénaturants, le polymorphisme caractéristique de la kératine assemblée in vitro, ainsi que la diminution mesurée du volume cellulaire et du niveau d'hydratation entre le stratum granulosum et le stratum corneum. [source] Cell-cycle regulation and mammalian gametogenesis: A lesson from the unexpectedMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 8 2006Abraham L. Kierszenbaum Abstract The progression of mammalian gametogenesis requires a precise balance between cell-cycle activities and elimination of defective gametogenic cells to ensure the perpetuation of species. Both spermatogonia and oogonia are stem cell populations committed to meiosis with the aim of generating haploid gametes for fertilization. At puberty, mitotically dividing spermatogonial cell cohorts maintain the ability of cell renewal and occupy niches in the seminiferous tubule. In contrast, mitotically dividing oogonial cell cohorts produced in the fetal ovary, are exclusively committed to meiosis and produce primordial follicles housing a primary oocyte surrounded by somatic follicular cells. A consistent physiological event during mammalian gametogenesis is the disposal of spermatogenic cells by apoptosis and ovarian follicles by atresia. Cyclin-dependent kinases (Cdks) and their cyclin partners coordinate the activities of the cell cycle. An additional cell-cycle regulatory component is the centrosome. The centrosome harbors regulatory proteins controlling the normal progression of the cell cycle. Changes in individual centrosome proteins can lead to cell-cycle arrest and a decrease in the genomic protective function of p53 that promotes apoptosis. Disruption of cyclin A1, Cdk2, and Cdk4 expression in transgenic mice results in infertility and gonadal atrophy. Cdk,cyclin complexes interact with regulatory proteins, which may fine-tune the activities of the complex. One of the many regulatory proteins is p12, a 115 amino acid growth suppressor polypeptide designated p12CDK2AP1, partner of Cdk2 and with binding affinity to DNA polymerase ,/primase. Overexpression of p12 is associated with testicular and ovarian atrophy without affecting fertility. Ectopic expression of p12 was driven by the keratin 14 promoter. Keratin 14 is the pairing partner of keratin 5 and both keratins are expressed in testis. The efficiency of keratin promoters in driving ectopic gonadal gene expression, the association of gonadal atrophy with the ectopic expression of a Cdk2 regulatory protein and the centrosome, as a reservoir of cell-cycle regulatory proteins, open new experimental opportunities to address still lingering questions concerning cell differentiation and division during mammalian gametogenesis. Mol. Reprod. Dev. 939,942, 2006. © 2006 Wiley-Liss, Inc. [source] Keratin 17 mutation in pachyonychia congenita type 2 patient with early onset steatocystoma multiplex and Hutchinson-like tooth deformityTHE JOURNAL OF DERMATOLOGY, Issue 3 2006Se-Woong OH ABSTRACT Pachyonychia congenita type 2 (PC-2) is an autosomal dominant disorder characterized by hypertrophic nail dystrophy, focal keratoderma, multiple pilosebaceous cysts, and other features of ectodermal dysplasia. It has been demonstrated that PC-2 is caused by mutations in the keratin 17 and keratin 6b genes. In this report, we describe a missense mutation in the keratin 17 gene, M88T, in a Korean patient whose phenotype included early onset steatocystoma multiplex and Hutchinson-like tooth deformities along with other typical features of PC-2 such as hypertrophic nails, natal teeth and follicular hyperkeratosis. [source] Keratin 16 expression in epidermal melanocytesBRITISH JOURNAL OF DERMATOLOGY, Issue 1 2010J. Bhawan No abstract is available for this article. [source] Keratin 16 expression in epidermal melanocytes: reply from authorsBRITISH JOURNAL OF DERMATOLOGY, Issue 1 2010Y. Ramot No abstract is available for this article. [source] Promotion of Skin Carcinogenesis by Dimethylarsinic Acid in Keratin (K6)/ODC Transgenic MiceCANCER SCIENCE, Issue 6 2000Takashi Morikawa Dimethylarsinic acid (DMA) is a major metabolite of inorganic arsenicals in mammals, and arsenic exposure is associated with tumor development in a wide variety of human tissues, particularly the skin. Transgenic mice with ornithine decarboxylase (ODC) targeted to hair follicle keratinocytes are much more sensitive than littermate controls to carcinogens. In this study we investigated the promoting effect of DMA on skin carcinogenesis in such K6/ODC transgenic mice. The back skin of female C57BL/6J K6/ODC transgenic mice, 10 to 14 weeks old, was initiated with topical application of 7,12-dimethylbenz[,]anthracene (DMBA) at a dose of 50 ,g or acetone alone on day 1 of the experiment, followed by treatment with 3.6 mg of DMA, 5 ,g of 12-O-tetradecanoylphorbol-13-acetate (TPA) or neutral vehicle (control) twice a week for 18 weeks. Mice were killed 1 week after the end of the treatment. Induction of skin tumors was significantly accelerated in the DMA-treated group, as well as in the TPA-treated group, indicating that DMA has a promoting effect on skin tumorigenesis in K6/ODC transgenic mice. [source] Clinical heterogeneity in recessive epidermolysis bullosa due to mutations in the keratin 14 gene, KRT14CLINICAL & EXPERIMENTAL DERMATOLOGY, Issue 6 2008E. Yiasemides Summary Background., Epidermolysis bullosa simplex (EBS), the most common subtype of EB, is usually inherited as an autosomal dominant trait caused by mutations in either the keratin 5 (KRT5) or keratin 14 (KRT14) genes. Recessive EBS (R-EBS) is extremely rare. Methods., We present the first Australian patient diagnosed with R-EBS, to our knowledge, and a comprehensive review of genotypes and phenotypes of R-EBS reported cases. Results., The female proband, of Turkish descent with consanguineous parentage, was referred to us at the age of 8 years. Clinically, she had a severe phenotype including generalized blisters, mucosal involvement and EB naevi. Immunofluorescence mapping and electron microscopy were consistent with a diagnosis of EBS. Staining for Keratin 14 (K14) was negative. The basal layer, however, reacted with monoclonal antibodies to keratins 6 (K6) and 16 (K16). Mutation screening from genomic DNA showed that the proband was homozygous for the truncation mutation Y204X in exon 3 of KRT14, and both unaffected parents were heterozygous for a single KRT14 Y204X mutation. The phenotype of our patient is reported in more detail and with longer follow-up than those of others published in the literature. Discussion., The proband's phenotype was severe as an infant but improved with age, suggesting that an alternative keratin is pairing with K5 in her skin to compensate for the loss of K14 , a novel biological compensatory mechanism. It is interesting that K6 and K16 were expressed, as these are normally positive in hyperproliferative skin disorders. [source] Autophagy activation by rapamycin eliminates mouse Mallory-Denk bodies and blocks their proteasome inhibitor-mediated formation,HEPATOLOGY, Issue 6 2008Masaru Harada The proteasomal and lysosomal/autophagy pathways in the liver and other tissues are involved in several biological processes including the degradation of misfolded proteins. Exposure of hepatocyte cell lines to proteasome inhibitors (PIs) results in the formation of inclusions that resemble Mallory-Denk bodies (MDBs). Keratins are essential for MDB formation and keratin 8 (K8)-overexpressing transgenic mice are predisposed to MDB formation. We tested the hypothesis that PIs induce MDBs in vivo and that autophagy participates in MDB turnover. The effect of the PI bortezomib (which is used to treat some malignancies) on MDB formation was tested in K8-overexpressing mice and in cultured cells. Inclusion formation was examined using immune and conventional electron microscopy (EM). Bortezomib induced MDB-like inclusions composed of keratins, ubiquitin, and p62 in cultured cells. Short-term exposure to bortezomib induced similar inclusions in K8-overexpressing but not in nontransgenic mice, without causing liver injury. In bortezomib-treated mice, autophagy was activated in hepatocytes as determined by EM and biochemical analysis. Further activation of autophagy by rapamycin (Rap) decreased the number of inclusions in bortezomib-treated K8 transgenic mice significantly. Rap also led to resorption of spontaneously formed MDBs in aging K8-overexpressing mice. Immune EM demonstrated K8-positive and ubiquitin-positive structures in autophagic vacuoles in the mouse liver. Conclusion: PIs alone are sufficient to induce MDBs in susceptible animals, while Rap-mediated activation of autophagy prevents MDB formation and causes MDB resorption. These findings suggest that some patients treated with PIs may become predisposed to MDB formation. Autophagy provides a potential cellular mechanism for the resorption of cytoplasmic inclusions. (HEPATOLOGY 2008.) [source] Fabrication of protein-doped PLA composite nanofibrous scaffolds for tissue engineeringPOLYMER INTERNATIONAL, Issue 10 2008Jiang Yuan Abstract BACKGROUND: Electrospinning is known as a novel fabrication method to form nanofibrous scaffolds for tissue-engineering application. Previously, many natural biopolymers of protein have been electrospun. However, keratin has not attracted enough attention. In this study, keratin and gelatin were co-electrospun with polylactide (PLA), respectively. RESULTS: The resulting nanofibers were characterized by a field emission scanning electron microscope (FE-SEM), an attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and an electron spectroscopy for chemical analysis (ESCA). The biodegradation of mats in the presence of trypsin solution was studied. Cell attachment experiments showed that NIH 3T3 cells adhered more and spread better onto the PLA/keratin and PLA/gelatin nanofibrous mats than that onto the blank PLA mats. MTT and BrdU assay showed that PLA/keratin and PLA/gelatin nanofibrous mats could both accelerate the viability and proliferation of fibroblast cells as compared to PLA nanofibrous mats. CONCLUSION: The present study suggests that the introduction of gelatin and keratin can both improve cell-material interaction, especially, the former is more effective. Copyright © 2008 Society of Chemical Industry [source] Ultrastructural characteristics of the process of cornification in developing claws of the brushtail possum (Trichosurus vulpecula)ACTA ZOOLOGICA, Issue 3 2009Lorenzo Alibardi Abstract Cornification of developing claws in the brush possum has been analysed by electron microscopy and compared with the process in other tetrapods. Newborns from 3 to 60 days postparturition were studied. After formation of symmetric and round outgrowth in digits the epidermis becomes thicker in the dorsal with respect to the ventral digit tip. The claw elongates forming the unguis and a shorter subunguis. Spinosus keratinocytes in both unguis and subunguis accumulate tonofilaments that fill their cytoplasm. Keratohyaline-like granules are formed in early stages of differentiation in both unguis and subunguis but they later disappear in highly cornified corneocytes. Tonofilaments become electron-dense in keratinocytes of the precorneous layer in the large corneocytes of the unguis and in narrow corneocytes of the subunguis. Keratin bundles transform into an amorphous corneous material that embeds or masks the original keratin intermediate filaments. Nucleated corneocytes are accumulated in the unguis while thinner corneocytes are present in the subunguis. The latter contain a dense material, possibly containing high sulphur keratin associated proteins, as occurs during cornifcation of the cortex and cuticle hair cells and in the nail. The process of cornification of mammalian claws is compared with that of reptilian and avian claws. [source] Cell organization of barb ridges in regenerating feathers of the quail: implications of the elongation of barb ridges for the evolution and diversification of feathersACTA ZOOLOGICA, Issue 2 2007L. Alibardi Abstract This ultrastructural study on the regenerating feathers of quail describes the cellular organization of the barb ridges responsible for the ramification of adult feathers. Bilateral symmetry of the barb ridges determines the organization of feather cells into feather branching. The length of the barb ridges, derived from the number of cells associated to form the barbule plates, determines the length of the barbule branching. Long chains of barb cells form long barbs that branch from the rachis with an increase of feather size. Supportive cells function as spacers between the barbule cells. New cells derive from stem cells localized in the collar region of the feather follicle, as indicated from the re-organization of collar cells into barb ridges (a morphogenetic process inherited from that of embryonic feathers), production of an embryonic type of keratin (feather keratin), permanence of periderm granules (typical embryonic organelles) in barb vane ridge cells. Variations in the process of barb ridge morphogenesis allow the fusion of ridges into a rachis. The differentiation of hooklets contributes to the origin of planar feathers. Separation between rachis and merging barb ridges is by supportive cells, derived from the marginal plates of the barb ridges. Speculations on the evolution and diversification of feathers are presented. [source] Differentiation of the epidermis of scutes in embryos and juveniles of the tortoise Testudo hermanni with emphasis on beta-keratinizationACTA ZOOLOGICA, Issue 3 2005L. Alibardi Abstract The sequence of differentiation of the epidermis of scutes during embryogenesis in the tortoise Testudo hermanni was studied using autoradiography, electron microscopy and immunocytochemistry. The study was mainly conducted on the epidermis of the carapace, plastron and nail. Epidermal differentiation resembles that described for other reptiles, and the embryonic epidermis is composed of numerous cell layers. In the early stages of differentiation of the carapacial ridge, cytoplasmic blebs of epidermal cells are in direct contact with the extracellular matrix and mesenchymal cells. The influence of the dermis on the formation of the beta-layer is discussed. The dermis becomes rich in collagen bundles at later stages of development. The embryonic epidermis is formed by a flat periderm and four to six layers of subperidermal cells, storing 40,70-nm-thick coarse filaments that may represent interkeratin or matrix material. Beta-keratin is associated with the coarse filaments, suggesting that the protein may be polymerized on their surface. The presence of beta-keratin in embryonic epidermis suggests that this keratin might have been produced at the beginning of chelonian evolution. The embryonic epidermis of the scutes is lost around hatching and leaves underneath the definitive corneous beta-layer. Beneath the embryonic epidermis, cells that accumulate typical large bundles of beta-keratin appear at stage 23 and at hatching a compact beta-layer is present. The differentiation of these cells shows the progressive replacement of alpha-keratin bundles with bundles immunolabelled for beta-keratin. The nucleus is degraded and electron-dense nuclear material mixes with beta-keratin. In general, changes in tortoise skin when approaching terrestrial life resemble those of other reptiles. Lepidosaurian reptiles form an embryonic shedding layer and crocodilians have a thin embryonic epidermis that is rapidly lost near hacthing. Chelonians have a thicker embryonic epidermis that accumulates beta-keratin, a protein later used to make a thick corneous layer. [source] Developmental changes in cellular and extracellular structural macromolecules in the secondary palate and in the nasal cavity of the mouseEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2010Forugh Vaziri Sani Vaziri Sani F, Kaartinen V, El Shahawy M, Linde A, Gritli-Linde A. Developmental changes in cellular and extracellular structural macromolecules in the secondary palate and nasal cavity of the mouse. Eur J Oral Sci 2010; 118: 221,236. © 2010 The Authors. Journal compilation© 2010 Eur J Oral Sci The aim of this study was to analyse the hitherto largely unknown expression patterns of some specific cellular and extracellular molecules during palate and nasal cavity development. We showed that epithelia of the developing palate and the vomerine epithelium express similar sets of structural proteins. With the exception of keratin 15, which becomes barely detectable in the elevated palatal shelves, nearly all of these proteins become upregulated at the presumptive areas of fusion and in the adhering epithelia of the palate and nasal septum. In vivo and in vitro analyses indicated that reduction in the amount of keratin 15 protein is independent of Tgf,,Alk5 signalling. Foxa1 expression also highlighted the regionalization of the palatal and nasal epithelia. Owing to the lack of reliable markers of the palatal periderm, the fate of peridermal cells has been controversial. We identified LewisX/stage-specific embryonic antigen-1 as a specific peridermal marker, and showed that numerous peridermal cells remain trapped in the medial epithelial seam (MES). The fate of these cells is probably apoptosis together with the rest of the MES cells, as we provided strong evidence for this event. Heparan sulphate, chondroitin-6-sulphate, and versican displayed dynamically changing distribution patterns. The hitherto-unknown innervation pattern of the developing palate was revealed. These findings may be of value for unravelling the pathogenesis of palatal clefting. [source] A novel mutation (p.Thr198Ser) in the 1A helix of keratin 5 causes the localized variant of Epidermolysis Bullosa SimplexEXPERIMENTAL DERMATOLOGY, Issue 7 2009Paul E. Bowden Abstract:, A novel missense mutation (p.Thr198Ser) in the 1A helix of keratin 5 (K5) has been identified in a four-generation family with a history of the localized variant of epidermolysis bullosa simplex (EBS-loc), a genetic skin fragility disorder caused by K5 or K14 mutations. Genomic DNA was isolated from blood samples of patients and their healthy relatives, and all exons of the genes encoding K5 and K14 (KRT5 and KRT14) were amplified by PCR and directly sequenced. The identified mutation was confirmed by mismatch allele-specific (MM-AS)-PCR and restriction enzyme digestion with RsaI. K5 p.Thr198Ser lies at the C-terminal end of the 1A helical domain and is considered to be outside of the main mutation hotspot region. This is the first reported mutation to affect position 30 of the 1A helix (1A:T30S) in any of the 54 known keratins. [source] Keratin 9 gene mutations in five Korean families with epidermolytic palmoplantar keratodermaEXPERIMENTAL DERMATOLOGY, Issue 6 2003Joo-Heung Lee Abstract:, Epidermolytic palmoplantar keratoderma (EPPK) is an autosomal dominant disease characterized clinically by localized palmoplantar thickening and histopathologically by granular degeneration of the epidermis. Recent molecular biological studies have revealed that EPPK is caused by mutations of the keratin 9 gene in sequences mainly encoding the highly conserved 1 A rod domain. Here we demonstrate a novel mutation of N160H (position 8 of the 1 A domain) and two other previously reported mutations, R162W and N160S, in five unrelated Korean families with EPPK. The three-dimensional structure of the 1 A domain of the related vimentin intermediate filament protein chain is now known. Based on its likely similarity to the keratin 9 chain, we predict that inappropriate amino acid substitutions in position 10 of 1 A will likely interfere with coiled-coil dimer stability, and those in position 8 will interfere with tetramer stability. Accordingly, these mutations compromise the structural integrity of the keratin intermediate filaments leading to the pathology of EPPK. [source] Novel keratin 16 mutations and protein expression studies in pachyonychia congenita type 1 and focal palmoplantar keratodermaEXPERIMENTAL DERMATOLOGY, Issue 3 2000F. J. D. Smith Abstract: Pachyonychia congenita type 1 (PC-1) is an autosomal dominant ectodermal dysplasia characterized by nail dystrophy, focal non-epidermolytic palmoplantar keratoderma (FNEPPK) and oral lesions. We have previously shown that mutations in keratin 16 (K16) cause fragility of specific epithelia resulting in phenotypes of PC-1 or FNEPPK alone. Here, we report 2 novel mutations in K16 causing distinct phenotypes. A heterozygous missense mutation (L124R) was detected in a kindred with PC-1. In a family where mild FNEPPK was the only phenotype, a 23 bp deletion and a separate 1 bp deletion downstream were found in exon 6: [1244,1266del; 1270delG]. At the protein level, these mutations remove 8 residues and substitute 2 residues in the helix termination motif (HTM) of the K16 polypeptide. The HTM sequence is conserved in all known intermediate filament proteins and for convenience, this complex mutation was designated ,HTM. Transient expression of K16 cDNAs carrying either the L124R or the ,HTM mutation in epithelial cell line PtK2 produced aggregation of the keratin cytoskeleton. However, the aggregates observed with the ,HTM mutation were morphologically different and appeared to be less disruptive to the endogenous cytoskeleton. Therefore, loss of the HTM sequence may render this mutant K16 less capable of contributing to filament assembly and decrease its dominant-negative effect, resulting in the milder FNEPPK phenotype. [source] Hot spot mutations in keratin 2e suggest a correlation between genotype and phenotype in patients with ichthyosis bullosa of SiemensEXPERIMENTAL DERMATOLOGY, Issue 1 2000Y. Suga Abstract: Ichthyosis bullosa of Siemens (IBS) is a rare disorder of cornification characterized by blister formation in the upper suprabasal layers of the epidermis. Molecular analysis of IBS has identified mutations in the keratin 2e (K2e) gene, which is located in the type II keratin gene cluster on chromosome 12q. We have studied two IBS families and have identified heterozygous point mutations in codon 493 of the K2e gene in both families. Whereas a non-conservative amino acid substitution at position 117 of the 2B region of K2e (E117K) was associated with a severe phenotype in family 1, family 2 showed mild clinical features as a result of a conservative substitution (E117D). These data suggest a phenotype,genotype correlation in these families. [source] Identification of a novel mutation in keratin 1 in a family with epidermolytic hyperkeratosisEXPERIMENTAL DERMATOLOGY, Issue 1 2000M. J. Arin Abstract: Epidermolytic hyperkeratosis (EHK) is a hereditary skin disorder typified by blistering due to cytolysis. One in 100,000 individuals is affected by this autosomal-dominant disease. The onset of the disease phenotype is typically at birth. Histological and ultrastructural examination of the epidermis shows a thickened stratum corneum and tonofilament clumping around the nucleus of suprabasal keratinocytes. Linkage studies localized the disease genes on chromosomes 12q and 17q which contain the type II and type I keratin gene clusters. Recently, several point mutations in the genes encoding the suprabasal keratins, K1 and K10, have been reported in EHK patients. We have investigated a large kindred affected by EHK and identified a new point mutation in the 2B region of keratin 1 (I107T), resulting from a T to C transition in codon 478. [source] Protein kinase C , phosphorylates keratin 8 at Ser8 and Ser23 in GH4C1 cells stimulated by thyrotropin-releasing hormoneFEBS JOURNAL, Issue 13 2007Yoshiko Akita Protein kinase C , (PKC,) is activated by thyrotropin-releasing hormone (TRH), a regulator of pituitary function in rat pituitary GH4C1 cells. We analyzed the downstream mechanism after PKC, activation. Exposure of GH4C1 cells to TRH or a phorbol ester increased the phosphorylation of three p52 proteins (p52a, p52b and p52c) and decreased the phosphorylation of destrin and cofilin. GF109203X, an inhibitor of protein kinases including PKC, inhibited phosphorylation of the p52 proteins by TRH stimulation. Peptide mapping, amino-acid sequencing, and immunochemical studies indicated that p52a, p52b, and p52c are the differentially phosphorylated isoforms of keratin 8 (K8), an intermediate filament protein. The unphosphorylated K8 (p52n) localized exclusively to the cytoskeleton, whereas the phosphorylated forms (especially p52c), which are increased in TRH-stimulated cells, localized mainly to the cytosol. K8 phosphorylation was enhanced in PKC,-overexpressing clones, and purified recombinant PKC, directly phosphorylated K8 with a profile similar to that observed in TRH-stimulated cells. PKC, and K8 colocalized near the nucleus under basal conditions and were concentrated in the cell periphery and cell,cell contact area after TRH stimulation. MS analyses of phospho-K8 and K8-synthesized peptide (amino acids 1,53) showed that PKC, phosphorylates Ser8 and Ser23 of K8. Phosphorylation of these sites is enhanced in TRH-stimulated cells and PKC,-overexpressing cells, as assessed by immunoblotting using antibodies to phospho-K8. These results suggest that K8 is a physiological substrate for PKC,, and the phosphorylation at Ser8 and Ser23 transduces, at least in part, TRH,PKC, signaling in pituitary cells. [source] Autophagy activation by rapamycin eliminates mouse Mallory-Denk bodies and blocks their proteasome inhibitor-mediated formation,HEPATOLOGY, Issue 6 2008Masaru Harada The proteasomal and lysosomal/autophagy pathways in the liver and other tissues are involved in several biological processes including the degradation of misfolded proteins. Exposure of hepatocyte cell lines to proteasome inhibitors (PIs) results in the formation of inclusions that resemble Mallory-Denk bodies (MDBs). Keratins are essential for MDB formation and keratin 8 (K8)-overexpressing transgenic mice are predisposed to MDB formation. We tested the hypothesis that PIs induce MDBs in vivo and that autophagy participates in MDB turnover. The effect of the PI bortezomib (which is used to treat some malignancies) on MDB formation was tested in K8-overexpressing mice and in cultured cells. Inclusion formation was examined using immune and conventional electron microscopy (EM). Bortezomib induced MDB-like inclusions composed of keratins, ubiquitin, and p62 in cultured cells. Short-term exposure to bortezomib induced similar inclusions in K8-overexpressing but not in nontransgenic mice, without causing liver injury. In bortezomib-treated mice, autophagy was activated in hepatocytes as determined by EM and biochemical analysis. Further activation of autophagy by rapamycin (Rap) decreased the number of inclusions in bortezomib-treated K8 transgenic mice significantly. Rap also led to resorption of spontaneously formed MDBs in aging K8-overexpressing mice. Immune EM demonstrated K8-positive and ubiquitin-positive structures in autophagic vacuoles in the mouse liver. Conclusion: PIs alone are sufficient to induce MDBs in susceptible animals, while Rap-mediated activation of autophagy prevents MDB formation and causes MDB resorption. These findings suggest that some patients treated with PIs may become predisposed to MDB formation. Autophagy provides a potential cellular mechanism for the resorption of cytoplasmic inclusions. (HEPATOLOGY 2008.) [source] Carcinomas arising in multilocular thymic cysts of the neck: a clinicopathological study of three casesHISTOPATHOLOGY, Issue 1 2004C A Moran Aims :,To report three cases of primary carcinoma of the neck arising in multilocular thymic cysts (MTC). Methods and results :,The patients were three men aged 47, 50 and 52 years who presented with a painless neck mass of several weeks' duration. The patients had no history of previous surgical procedures or of malignancy elsewhere. The tumours in all three patients were located on the right lateral side of the neck; all patients underwent complete surgical resection of the mass. Grossly, the tumours were cystic and measured between 20 and 30 mm in greatest diameter. Histologically, the tumours showed cyst walls lined by squamous epithelium. The cyst walls contained prominent germinal centres with lymphoid hyperplasia, cholesterol cleft granulomas, and scattered keratinized structures reminiscent of Hassall's corpuscles. In addition, a neoplastic cellular proliferation composed of round to oval cells arranged in sheets and originating from the lining of the cystic structures was present. The neoplastic cells showed moderate amounts of eosinophilic cytoplasm, round nuclei, and, in some areas, prominent nucleoli. Mitotic figures were easily found, and cellular pleomorphism was present in several areas. In two cases the tumours showed features of basaloid carcinoma of the thymus, while in one case the pattern was that of squamous cell carcinoma. Immunohistochemical studies for keratin showed a strong positive reaction in the tumour cells, while leucocyte common antigen strongly stained the lymphoid background. Follow-up information obtained in two patients showed them to be alive 6 months after initial diagnosis. One patient was lost to follow-up. Conclusion :,The cases described here represent an unusual variant of carcinoma arising in multilocular thymic cyst in the neck region. [source] Loss of intercellular adhesion activates a transition from low- to high-grade human squamous cell carcinomaINTERNATIONAL JOURNAL OF CANCER, Issue 4 2006Alexander Margulis Abstract The relationship between loss of intercellular adhesion and the biologic properties of human squamous cell carcinoma is not well understood. We investigated how abrogation of E-cadherin-mediated adhesion influenced the behavior and phenotype of squamous cell carcinoma in 3D human tissues. Cell-cell adhesion was disrupted in early-stage epithelial tumor cells (HaCaT-II-4) through expression of a dominant-negative form of E-cadherin (H-2Kd -Ecad). Three-dimensional human tissue constructs harboring either H-2Kd -Ecad-expressing or control II-4 cells (pBabe, H-2Kd -Ecad,C25) were cultured at an air-liquid interface for 8 days and transplanted to nude mice; tumor phenotype was analyzed 2 days and 2 and 4 weeks later. H-2Kd -Ecad-expressing tumors demonstrated a switch to a high-grade aggressive tumor phenotype characterized by poorly differentiated tumor cells that infiltrated throughout the stroma. This high-grade carcinoma revealed elevated cell proliferation in a random pattern, loss of keratin 1 and diffuse deposition of laminin 5 ,2 chain. When II-4 cell variants were seeded into type I collagen gels as an in vitro assay for cell migration, we found that only E-cadherin-deficient cells detached, migrated as single cells and expressed N-cadherin. Function-blocking studies demonstrated that this migration was matrix metalloproteinase-dependent, as GM-6001 and TIMP-2, but not TIMP-1, could block migration. Gene expression profiles revealed that E-cadherin-deficient II-4 cells demonstrated increased expression of proteases and cell-cell and cell-matrix proteins. These findings showed that loss of E-cadherin-mediated adhesion plays a causal role in the transition from low- to high-grade squamous cell carcinomas and that the absence of E-cadherin is an important prognostic marker in the progression of this disease. © 2005 Wiley-Liss, Inc. [source] Escape from microenvironmental control and progression of intraepithelial neoplasiaINTERNATIONAL JOURNAL OF CANCER, Issue 6 2005Weitian Zhang Abstract We previously reported that normal human keratinocytes controlled neoplastic progression of tumor cells at an early stage of transformation in stratified squamous epithelium. We now studied if cells at a more advanced stage of transformation were also subject to such microenvironmental control. To accomplish this, 3D human tissues that mimic intraepithelial neoplasia were fabricated by mixing genetically marked (,-gal), early-stage (II-4 cells) or advanced-stage (SCC13) transformed keratinocytes with normal keratinocytes, and tumor cell fate and phenotype were monitored in organotypic culture and after surface transplantation to nude mice. In vivo, SCC13 cells evaded local growth suppression to undergo connective tissue invasion at significantly lower tumor cell volumes (12:1, 50:1 normal:tumor cells) than II-4 cells. This behavior was explained by the growth suppression of II-4 cells, while advanced-stage tumor cells escaped this control and continued to undergo clonal expansion in mixed cultures to form large, intraepithelial tumor clusters. These communities of tumor cells underwent autonomous growth that was associated with altered expression of markers of differentiation (keratin 1) and cell,cell communication (connexin-43). Furthermore, significantly greater numbers of SCC13 cells expanded into a basal position after low-calcium stripping of suprabasal cells of mixed cultures compared to II-4 cells, suggesting that expansion of these cells enabled tumor cell invasion after transplantation. These findings demonstrated that early tumor development in human stratified squamous epithelium required escape from microenvironmental growth control that was dependent on the transformation stage of intraepithelial tumor cells during the premalignant stage of cancer progression. © 2005 Wiley-Liss, Inc. [source] Stratum corneum keratin structure, function and formation , a comprehensive reviewINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 6 2006L. Norlén Synopsis A comprehensive review on stratum corneum keratin organization, largely based on the recently published cubic rod-packing and membrane templating model [J. Invest. Dermatol., 123, 2004, 715], is presented. Keratin is the major non-aqueous component (wt/wt) of stratum corneum. As 90,100% of the stratum corneum water is thought to be located intracellularly one may presume that keratin also is a major factor (together with filaggrin-derived free amino acids) determining stratum corneum hydration level and water holding capacity. This water holding capacity depends in turn on the structural organization of the corneocyte keratin intermediate filament network. The cubic rod-packing model for the structure and function of the stratum corneum cell matrix postulates that corneocyte keratin filaments are arranged according to a cubic-like rod-packing symmetry. It is in accordance with the cryo-electron density pattern of the native corneocyte keratin matrix and could account for the swelling behaviour and the mechanical properties of mammalian stratum corneum. The membrane templating model for keratin dynamics and for the formation of the stratum corneum cell matrix postulates the presence in viable epidermal cellular space of a highly dynamic small lattice parameter (<30 nm) membrane structure with cubic-like symmetry, to which keratin is associated. It further proposes that membrane templating, rather than spontaneous self-assembly, is responsible for keratin intermediate filament formation and dynamics. It is in accordance with the cryo-electron density patterns of the native keratinocyte cytoplasmic space and could account for the characteristic features of the keratin network formation process, the dynamic properties of keratin intermediate filaments, the close lipid association of keratin, the insolubility in non-denaturating buffers and pronounced polymorphism of keratin assembled in vitro, and the measured reduction in cell-volume and hydration level between stratum granulosum and stratum corneum. Résumé, La kératine est le composant majeur anhydre de la couche cornée. Etant donné que l'on considère que 90 à 100% de l'eau de la couche cornée est localisée à l'intérieur des cellules, on peut penser que la kératine joue également un rôle important (en association avec les acides aminés libres dérivés de la filagrine) dans le niveau d'hydratation de la couche cornée et sa capacité de rétention de l'eau. Cette capacité de rétention de l'eau dépend elle-même de l'organization structurelle du réseau de filaments intermédiaires de la kératine des cornéocytes. Le modèle de cylindre en réseau cubique appliquéà la structure et aux fonctions de la matrice des cellules de la couche cornée stipule que les filaments de la kératine des cornéocytes sont disposés symétriquement, les paquets de fibrilles formant une structure cubique. Ceci est conforme au modèle de densité cryo-électronique de la matrice kératinique des cornéocytes natifs et pourrait expliquer le comportement de gonflement et les propriétés mécaniques de la couche cornée des mammifères. Le modèle d'assemblage membranaire appliquéà la dynamique de la kératine et à la formation de la matrice cellulaire du stratum cornéum postule la présence dans l'espace cellulaire viable de l'épiderme d'une structure membranaire hautement dynamique présentant un petit paramètre de maille (<30 nm) et une organization en forme de cube, à laquelle la kératine est associée. D'autre part, ce modèle suggère qu'un assemblage membranaire plutôt qu'un auto-assemblage spontané puisse être à l'origine de la formation des filaments intermédiaires de kératine et de leur dynamique. Ceci concorde avec les modèles de densité cryo-électronique du cytoplasme des kératinocytes natifs et pourrait expliquer les caractéristiques du processus de formation du réseau kératinique, les propriétés dynamiques des filaments intermédiaires de kératine, l'association de la kératine avec les lipides, l'insolubilité dans les tampons non dénaturants, le polymorphisme caractéristique de la kératine assemblée in vitro, ainsi que la diminution mesurée du volume cellulaire et du niveau d'hydratation entre le stratum granulosum et le stratum corneum. [source] Nonmutilating palmoplantar and periorificial kertoderma: a variant of Olmsted syndrome or a distinct entity?INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 6 2010Ahmad Nofal MD Background, Olmsted syndrome is a rare keratinization disorder characterized by mutilating palmoplantar and periorificial keratoderma as the two major diagnostic features. Some authors believe that atypical cases without this standard combination may not really belong to Olmsted syndrome. Herein, we describe two familial cases with congenital nonmutilating palmoplantar and periorificial keratoderma, and discuss their similarities and differences with Olmsted syndrome. Patients, The study included two sisters who presented with focal and punctate nonmutilating palmoplantar keratoderma (PPK), periorificial hyperkeratotic plaques, and widely distributed keratotic lesions. Fragile denuded areas of the skin were found in sites exposed to trauma. Fingernails showed a characteristic form of leukonychia. Results, Histopathology of plantar keratoderma showed psoriasiform hyperplasia with marked compact hyperkeratosis, while vicinity of denuded skin revealed thin parakeratotic zone and dissolution of the granular cell layer. Immunohistochemistry demonstrated suprabasal staining pattern for acidic keratin (AE1) and uniform positivity, starting four to six layers above the basal layer, for cytokeratin 10. Electron microscopy showed defective keratinization. Cytogenetic studies revealed normal karyotype and no chromosomal breakage. Conclusion, Our cases share Olmsted syndrome in the early onset, and the presence of symmetrical PPK, periorificial keratoderma and keratotic lesions. However, the striking nonmutilating nature of PPK and the presence of unique features in our patients suggest a newly described keratinization disorder. [source] Immunohistochemical study of cytokeratin expression in nevus sebaceousINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 4 2010Ichiro Kurokawa MD Background, The histogenesis of nevus sebaceous (NS) is unclear. Methods, To elucidate the histogenesis of NS, cytokeratin (CK) profiles were examined immunohistochemically using 10 anti-keratin antibodies in the three stages of NS. Results, In the first stage, stratified differentiated keratins (CK1 and 10) were reduced, and basal keratin (CK14) was increased in the epidermis and primitive follicular structure (PFS). In the second stage, in addition to reduced CK1 and CK10 expressions and increased CK14 expression, CK17 expression was strongly expressed in the sebaceous ducts in proportion to the development of sebaceous gland. In the third stage, CK14, CK17 and CK19 were expressed in secondary tumors. CK16 was not detected throughout all stages of NS. Conclusion, These results suggest that NS is not hyperproliferative but involves hamartomatous differentiation with undifferentiated keratins. [source] Multiple keratoacanthomas in a young woman: report of a case emphasizing medical management and a review of the spectrum of multiple keratoacanthomasINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 1 2007Ron J. Feldman MD A 27-year-old white woman was referred for consultation with regard to the presence of extensive multiple keratotic lesions. She began to develop these lesions at the age of 9 years, with healing of the lesions resulting in scar formation. A biopsy was performed at the age of 16 years, but the patient was unsure of the results. Since then, she had not had any treatment or biopsies, and stated that she had not suffered from any health problems during the intervening period. She was most concerned about the tumors on her heels and soles, which caused difficulty with ambulation. The family history was negative for skin diseases, including melanoma, nonmelanoma skin cancer, psoriasis, and eczema, and positive for Type II diabetes mellitus. A relative reported that the patient's grandfather had similar lesions, but the patient's parents and siblings were healthy. She was married and had one child, a 9-year-old daughter. Her child had no skin lesions. The patient's only medication was Ortho-Tricyclene birth control pills. She had no known drug allergies. Physical examination revealed the presence of multiple lesions on her body (Fig. 1). Her left superior helix contained a well-demarcated, dome-shaped nodule with a rolled, mildly erythematous border with a central hyperkeratotic plug. A similar lesion was present in the scaphoid fossa of the left ear and smaller lesions were scattered on her face. Numerous lesions were present on the arms and legs bilaterally, with the majority of lesions being located on the anterior lower legs. There were also lesions present on the palms and soles. The lesions ranged in size from 5 mm to 3 cm, the largest being a verrucous exophytic nodule on the anterior aspect of her left leg. Overall, there appeared to be two distinct types of lesion. One type appeared round, oval, and symmetric with a central keratotic plug, similar to that on the ear. The other type was larger, more exophytic, and verrucous, including the lesions on the volar surfaces. Also present were numerous, irregularly shaped atrophic scars where previous lesions had healed spontaneously. There were no oral lesions or lesions on her fingernails or toenails, and her teeth and hair were normal. Figure 1. Initial presentation of left ear and anterior legs before treatment A biopsy was obtained from an early lesion on the right dorsal forearm. Histology revealed an exo-/endophytic growth having a central crater containing keratinous material (Fig. 2). The crater was surrounded by markedly hyperplastic squamous epithelium with large squamous epithelial cells having abundant glassy cytoplasm. Some cells were dyskeratotic. Within the dermis was a dense, chiefly mononuclear inflammatory infiltrate. A buttress of epidermis surrounded the crater. The clinical and pathologic data were consistent with keratoacanthomas. Figure 2. Keratoacanthoma exhibiting an exo- and endophytic growth pattern with a central crater containing keratin (hematoxylin and eosin; original magnification, ×40) Initial laboratory screenings revealed elevated triglycerides and total cholesterol, 537 mg/dL (normal, < 150 mg/dL) and 225 mg/dL (normal, < 200 mg/dL), respectively, with all other laboratory results within normal limits. In anticipation of starting oral retinoid therapy for her multiple keratoacanthomas, she was referred to her primary care physician for control of hyperlipidemia. After her lipids had been controlled, she was placed on isotretinoin (Accutane) 40 mg/day. There was some interval improvement with regression of some lesions leaving atrophic scars. She was also started on topical application of tazarotene (Tazorac) for all nonresolving lesions. Possible side-effects from the isotretinoin occurred, including dry mouth and eyes. After 8 months of isotretinoin, the patient was switched to acitretin (Soriatane) 25 mg to determine whether it might have a more beneficial effect on the resistant lesions. Many of the larger lesions regressed leaving atrophic scars. The dose of acitretin was subsequently increased to 35 mg because the lesions on her heel and the ball of her foot persisted. Almost all of the lesions resolved, except those on her feet, which are slowly regressing. Currently, the patient is on a regimen of acitretin 25 mg once a day with tazarotene 0.1% gel applied directly to the few residual keratoacanthomas on her feet, which are slowly improving. [source] Epidermolytic hyperkeratosis: a keratin 1 or 10 mutational eventINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 1 2005Nicole L. Lacz MD Epidermolytic hyperkeratosis is an unusual type of ichthyosis. This inherited keratinization disorder is characterized clinically by erythema, blistering, and peeling shortly after birth. It may resolve and be replaced with thick scaling. It can lead to life-threatening complications, such as sepsis. Histologically, there is a hyperkeratosis and vacuolar degeneration. Genetically, this is an autosomal dominant disease with complete penetrance; however, 50% are spontaneous mutations. The clinical phenotype is a result of alterations in the gene(s) for keratin 1 and/or 10. We review this disorder and its therapy, which is mainly symptomatic with emollients and retinoids. [source] A case of nevus comedonicus syndrome associated with neurologic and skeletal abnormalitiesINTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 10 2001Young-Joon Seo MD A 12-year-old male was referred to us with recurrent pus discharge from tender nodules on the right axilla dating from the neonatal period. The nodules were black, characterized by scarring with dilated follicular openings and there were black papules filled with comedo-like keratin plugs in both axillae. Physical examination revealed a bowing deformity of the right third finger and retardation in language ability. The patient was referred to the Departments of Neurology and Orthopedics in Chungnam National University Hospital, Korea. Histologic examination of one of the black comedo-like lesions showed a bulbous and dilated infundibulum that contained laminated keratin, indicating a diagnosis of nevus comedonicus. A CT scan of the brain revealed dysgenesis of the corpus callosum. The IQ (intelligence quotient) score of the patient, measured by the Korean Wechsler Intelligence Scale for Children-Revised, was 94. The only difficulty noted for ordinary life was learning language. A radiograph of the right hand revealed hyperextension and an ulnar drift deformity of the right middle finger. Corrective osteotomy with external fixation and an iliac bone autograft were performed. Intermittent neurologic follow-up visits were ordered for the noted language deficit. At present the patient only exhibits difficulty in calculation. Oral antibiotics were administered to the skin lesions on occasion for secondary infections and inflammation of the cysts and comedones. Extraction of the comedones was performed as needed. [source] | ||||||||||||||||||||||||||||||||||