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H Winter

Publications and source records attributed to H Winter.

At least 91 records · Page 5Linked to original sources
PubMed1996

The region coding for the helix termination motif and the adjacent intron 6 of the human type I hair keratin gene hHa2 contains three natural, closely spaced polymorphic sites.

Mutations in distinct sites of epidermal keratins, in particular in the helix initiation and termination regions, cause human genodermatoses due to faulty intermediate filament formation. Extension of this observation to human hereditary hair and nail diseases includes population analyses of human hair keratin genes for natural sequence variations in the corresponding sites. Here we report on a large-scale genotyping of the short helix termination region (HTR) of the human type I cortical hair keratins hHa1, a3-I, and a3-II, and the cuticular hair keratin hHa2. We describe two polymorphic loci, P1 and P2, exclusively in the cuticular hHa2 gene, both creating dimorphic protein variants. P1 is due to a C to T mutation in a CpG element leading to a threonine to methionine substitution; P2 concerns a serine codon AGT that also occurs as an asparagine coding variant AAC. A third polymorphism, P3, is linked with a C to T point mutation located at the very beginning of intron 6. The three polymorphic sites are clustered in a 39-nucleotide sequence of the hHa2 gene. Both allelic frequency calculations in individuals of different races and pedigree studies indicate that the two-allelic hHa2 variants resulting from P1 and P2 occur ubiquitously in a ratio of about 1:1 (P1) and 2:1 (P2) respectively in our survey, and are clearly inherited as Mendelian traits. A genotype carrying both mutations simultaneously on one allele could not be detected in our sampling, and there was no association of a distinct allelic hHa2 variant with the known ethnic form variations of hairs. Sequence comparisons of the HTR of hHa2 with those of other type I hair keratins including the hHa2-ortholog from chimpanzee provide evidence that the P1- and P2-linked mutations must have occurred very early in human evolution and that the two P2-associated codon variants may be the result of two independent point mutations in an ancestral AGC serine codon. These data describe natural polymorphisms in the HTR of a member of the keratin multigene family.

Alleles↗
PubMed1996

Genomic characterization of the human type I cuticular hair keratin hHa2 and identification of an adjacent novel type I hair keratin gene hHa5.

Hair keratins, a subset of the keratin multigene family expressed in hard keratinizing structures, previously have been thought to comprise four members of each subfamily, designated Ha1-4 (type I) and Hb1-4 (type II), which are differentially expressed in the cuticle and cortex of the hair follicle. This report describes the genomic cloning and sequencing of the human type I cuticular hair keratin hHa2, as well as the identification of a previously unknown human type I hair keratin gene. The 12.5-kilobase pair genomic clone ghkI2.12, obtained by hybridization of a human genomic deoxyribonucleic acid library with a 3'-complementary deoxyribonucleic acid probe of hHa2, as well as the partially overlapping 14.4-kilobase pair genomic clone ghkI2.17, isolated using a 5'-fragment of clone ghkI2.12, allowed the characterization of the entire hHa2 gene. The gene displays the same exon/intron structure as two previously characterized type I mouse and sheep hair/wool keratin genes with strict positional conservation of the six introns in the region coding for the central alpha-helix. At the 5'-extremity of clone ghkI2.17, i.e., approximately 8.0 kilobase pairs upstream of the hHa2 gene and oriented in the same transcriptional direction, lies the gene for a hitherto unknown human type I hair keratin. Clone ghkI2.17 contains partial sequence information for this gene beginning with intron 5 and extending to the end of the gene. Screening of a human scalp complementary deoxyribonucleic acid library with a 3'-fragment of the gene yielded a full length complementary deoxyribonucleic acid clone of the new hair keratin, which in continuation of the current nomenclature for hair keratins was termed hHa5. Remarkably, the hHa5 gene, which contains an additional 7th intron in its 3'-noncoding region, is expressed mainly in supramatricial cells and lowermost cortical cells of the hair bulb and thus constitutes a very early component of hair morphogenesis. Our results confirm the type specific clustering of keratin genes and indicate that the human type I hair keratin subfamily contains more members than previously assumed.

Amino Acid Sequence↗
PubMed1996

[Value of lymphatic outflow directed continuity dissection in melanoma surgery].

Radicality of the surgical procedure in patients with intermediate and high risk melanomas is enhanced by the additional removal of the transit tract between tumor and regional lymph node (continuity dissection). After introduction of the lymphatic out flow scintigraphy in 1984, the accurate removal of the transit tract is easily possible in tumors located on the trunk, the upper arm and the thigh as well as of the head/neck region. The main reasons for the improved survival rates are the exact removal of the transit tract together with potentially existing occult tumor cells or in transit metastases, respectively, as well as ectope lymph node metastases and the consequent elective lymph node dissection.

Adult↗
PubMed1995

A cDNA encoding the human type I hair keratin hHal.

A full-length cDNA of a human type I hair keratin was isolated that encodes a protein of 416 amino acids. Northern blot analysis shows that the mRNA is present in human scalp but not in hairless skin. Based on sequence homology comparisons with the four known mouse type I hair keratins mHal-4 the keratin could be identified as the human hair keratin hHal.

Amino Acid Sequence↗
PubMed1995

Sequence data and chromosomal localization of human type I and type II hair keratin genes.

A cDNA library constructed with poly(A)+ RNA from human scalp was screened with selected fragments of both murine type I and type II hair keratin cDNAs. Two keratin clones, one type I, phKI-2, and one type II, phKII-1, were isolated and sequenced. In Northern blots, cDNA probes containing the 3'-noncoding sequences of the clones specifically hybridized to scalp mRNA species. Based on sequence homology comparisons with the four known murine type I hair keratins mHa1-4, the phKI-2 encoded keratin could be identified as human hair keratin hHa2. Similarly, sequence comparison with the four type II sheep wool keratins K2.9-12 revealed an orthologous relationship between the largest member of the type II wool keratin subfamily, K2.9 (i.e., sHb1) and the phKII-1 encoded human hair keratin (hHb1). The specific 3'-noncoding sequences of hHa2 and hHb1 were also used to isolate genomic fragments for both keratins from human genomic libraries which were than used for fluorescence in situ hybridization to human metaphase chromosomes. The hHa2 gene could be mapped to the long arm of chromosome 17, whereas the hHb1 gene was found on the long arm of chromosome 12. DAPI banding of the chromosomes allowed sublocalization of the hHa2 gene to 17q12-q21 and the hHb1 gene to 12q13, i.e., gene loci that have also been previously determined for human type I and type II epithelial keratins.

Amino Acid Sequence↗
PubMed1994

Pyrrolizidine alkaloid poisoning of yaks: identification of the plants involved.

A search was undertaken in the most eastern part of the Himalayan kingdom of Bhutan for the plants which are causing severe losses of yaks due to pyrrolizidine alkaloid poisoning. Two Senecio and three Ligularia species were found on yak pastures at altitudes between 3000 and 4000 m, including one so far underscribed Ligularia species. None was previously known to contain pyrrolizidine alkaloids. Another Senecio species was found between 2500 and 3000 m, an altitude too low for yaks to be kept but significant for other cattle. The search was supported by field chemical tests for the alkaloids and the diagnosis was later confirmed by thin layer chromatography and high pressure liquid chromatography. Two of the Senecio species had exceptionally high concentrations of pyrrolizidine alkaloids of about 0.5 per cent in the dry matter.

Altitude↗
PubMed1994

Sequence and expression of murine type I hair keratins mHa2 and mHa3.

A cDNA library was constructed with poly(A)+ RNA from mouse tail epidermis which contained all hair follicles of tail skin. The library was subjected to sequential screening procedures aimed at selecting cDNA clones coding for acidic, type I hair keratins. Two clones, pktI-2 and pktI-3, encoded keratins that could be identified as murine type I hair keratins mHa2 and mHa3, respectively, by positive hybridization selection analysis. Sequence comparisons with the known murine type I hair keratins mHa1 (Bertolino et al., J. Invest. Dermatol. 91, 541-546, 1988) and mHa4 (Bertolino et al., J. Invest. Dermatol. 94, 297-303, 1990) revealed a structural heterogeneity within the type I hair keratin subfamily. Three keratins, mHa1, mHa3, and mHa4, are highly related, differing mainly in the penultimate part of their amino and carboxy termini. In contrast, mHa2 is structurally distinct from the three other keratins in both the alpha-helix and, in particular, the non-alpha-helical domains. These findings are confirmed by evolutionary investigations and flexibility calculations which indicate a more flexible nature of the mHa2 amino terminus when compared to the corresponding region of the three other keratins. In situ hybridization experiments with specific 3' fragments of mHa2 and mHa3 show that mHa3 is expressed in cortex cells, whereas mHa2 transcripts are strictly limited to the cuticle of the hair shaft. mHa3 mRNA expression can also be demonstrated in the central unit of the murine lingual filiform papillae, whereas the cuticular keratin mHa2 is not expressed in this body site. These data indicate that the structural heterogeneity within the type I hair keratin subfamily is functionally relevant in the morphogenesis of hard alpha-keratin-expressing tissues.

Amino Acid Sequence↗
PubMed1994

Retinoic acid-induced normal and tumor-associated aberrant expression of the murine keratin K13 gene does not involve a promotor sequence with striking homology to a natural retinoic acid responsive element.

The type I keratin K13, normally restricted to suprabasal cells of internal stratified epithelia, is aberrantly expressed in 7,12-dimethylbenz[a]anthracene (DMBA)-12-O-tetradecanoyl-phorbol-13-acetate-induced murine epidermal tumors and constitutes an early marker of malignant progression. Aberrant K13 expression also occurs in epidermal cell lines derived from DMBA-TPA-induced tumors. As in cultured primary keratinocytes from normal internal stratified epithelia, the in vitro expression of K13 in transformed epidermal cell lines can be induced either by Ca2+ or by retinoic acid (RA). We have found that the promoter of the K13 gene contains a sequence element GGTTCA(N)5TGTTCT, in the following referred to as K13-RARE, that is highly related to the natural retinoic acid responsive element (RARE) of the retinoic acid receptor beta 2 gene. Both elements differ only in the second half-motifs, in which the first and sixth position is occupied by thymidines (K13-RARE) instead of adenines (beta 2-RARE), as well as in their pentameric spacer sequences. Despite this striking homology in the receptor binding domains, we show by transfection of reporter gene constructs of the elements into primary fore-stomach keratinocytes and transformed epidermal cell lines that in both cell systems, unlike beta 2-RARE, the wild-type K13-RARE completely lacks transactivating properties in the presence of RA. A recent hypothesis proposes that aberrant gene expression during tumorigenesis may occur through conversion of inactive response elements with high homology to hormone response elements into functional enhancers by carcinogen-induced point mutations at critical positions (Nawaz et al., Mol. Carcinogen., 7, 76-82, 1993). To investigate whether the aberrantly expressed K13 gene falls into the category of those genes, reporter gene constructs of K13-RARE variants in which either the initial or the terminal thymidine of the second half-motif was replaced by adenine were transfected into epidermal cell lines. Neither mutant exhibited RA-dependent transactivating properties. Strong transactivation could only be achieved by a K13-RARE mutant in which both critical thymidines were substituted by adenines. This type of closely spaced base exchange, unlikely to be created during DMBA initiation of mouse epidermis, was not detectable on sequencing genomic DNA of a squamous cell carcinoma and a transformed epidermal cell line. Instead, in both cases, only the wild-type K13-RARE could be demonstrated. A regulatory role of this RARE-like sequence in the promoter of the murine K13 gene for both normal and aberrant expression of the gene can therefore be excluded.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1994

The large type II 70-kDa keratin of mouse epidermis is the ortholog of human keratin K2e.

The basic keratin pattern of mammalian epidermis consists of the basal keratin pair K5/K14 and the differentiation-specific keratin pair K1/K10. Distinct skin sites of the adult mouse, i.e., ear, sole of the foot, and interscale regions of tail skin, express an additional, type II 70-kilodalton (kDa) keratin without a defined new type I partner in suprabasal epidermal cells. Until now, the question whether this large keratin is specific for the mouse (or related small rodents) or whether orthologous keratins exist in other species has not yet been answered. In the present study, we have determined the full-length amino acid sequence of the 70-kDa keratin. The keratin comprises 707 amino acid residues and has a calculated molecular weight of 70,976.70 Da. From the structural point of view, the 70-kDa keratin is remarkable in that more than half of both the V1 and V2 subdomains of its non alpha-helical head and tail portions consist of different glycine-rich peptide motifs that are configured consecutively at least two times and as much as seven times in tandem. By means of sequence comparisons and phylogenetic investigations, we show that the 70-kDa keratin represents the murine ortholog of the human 65-kDa keratin K2e, whose nature as a genuine keratin has recently been demonstrated. The unusually large size difference of 5 kDa between MK2e and HK2e is due mainly to a different duplication rate of the glycine-rich peptide motifs in the respective V subdomains of the orthologous keratins. We discuss the properties of these highly specialized keratins, which in both species define locally restricted epidermal keratin phenotypes, and compare them with other orthologous keratins that belong to the basic epidermal keratin pattern.

Amino Acid Sequence↗