Biomedical subjects

P Krieg

Publications and source records attributed to P Krieg.

At least 19 recordsLinked to original sources

PubMed2006

What are cyclooxygenases and lipoxygenases doing in the driver's seat of carcinogenesis?

Substantial evidence supports a functional role for cyclooxygenase- and lipoxygenase-catalyzed arachidonic and linoleic acid metabolism in cancer development. Genetic intervention studies firmly established cause-effect relations for cyclooxygenase-2, but cyclooxygenase-1 may also be involved. In addition, pharmacologic cyclooxygenase inhibition was found to suppress carcinogenesis in both experimental mouse models and several cancers in humans. Arachidonic acid-derived eicosanoid or linoleic acid-derived hydro[peroxy]fatty acid signaling are likely to be involved impacting fundamental biologic phenomena as diverse as cell growth, cell survival, angiogenesis, cell invasion, metastatic potential and immunomodulation. However, long chain unsaturated fatty acid oxidation reactions indicate antipodal functions of distinct lipoxygenase isoforms in carcinogenesis, i.e., the 5- and platelet-type 12-lipoxygenase exhibit procarcinogenic activities, while 15-lipoxygenase-1 and 15-lipoxygenase-2 may suppress carcinogenesis.

Animals↗

PubMed2006

15-Lipoxygenase-2 gene regulation by its product 15-(S)-hydroxyeicosatetraenoic acid through a negative feedback mechanism that involves peroxisome proliferator-activated receptor gamma.

An inverse relationship exists between the expression of 15-lipoxygenase-2 (15-LOX-2) and peroxisome proliferator-activated receptor gamma (PPARgamma) in normal prostate epithelial cells (PrECs) compared with their expression in prostate carcinoma cells (PC-3). The reason for this difference, however, is unknown. We hypothesized that this inverse expression partly involves the 15-LOX-2 promoter and 15-S-hydroxyeicosatetraenoic acid (15-(S)-HETE), a product of 15-LOX-2 that binds to PPARgamma. We identified an active steroid nuclear receptor half-site present in the 15-LOX-2 promoter fragment F-5 (-618/+177) that can interact with PPARgamma. After forced expression of wild-type PPARgamma, 15-(S)-HETE (1 microM) decreased F-5 reporter activity in PrECs whereas forced expression of 15-LOX-2 resulted in 15-(S)-HETE production which enhanced F-5 activity in PC-3. In contrast, the expression of dominant-negative PPARgamma reversed the transcriptional activation of F-5 by enhancing it 202-fold in PrEC or suppressing it in PC-3; the effect in PC-3 was positively increased 150-fold in the presence of 15-(S)-HETE (1 microM). Peroxisome proliferator-activated receptor gamma interacted with 15-LOX-2 promoter sequences in pulldown experiments using biotinylated 15-LOX-2 (-560/-596 bp) oligonucleotides. In gelshift analyses PPARgamma and orphan receptor RORalpha were shown to interact with the F-5 fragment in PC-3 cells. These data suggest that crosstalk mechanisms exist between the 15-LOX-2 gene and PPARgamma to counterbalance expression and help explain the inverse relationship of these genes in normal versus cancer cells.

5' Untranslated Regions↗

PubMed2003

LOX-DB-- database on lipoxygenases.

SUMMARY: Lipoxygenases are a family of enzymes involved in a variety of human diseases like inflammation, asthma, artherosclerosis and cancer. The lipoxygenases database (LOX-DB) aims to be a web accessible compendium of information in particular on the mammalian members of this multigene family. This resource includes molecular structures, reference data, tools for structural and computational analysis as well as links to related information maintained by others. The data can be retrieved by the use of various search options and analyzed applying publicly available visualization tools. AVAILABILITY: LOX-DB is available at http://www.dkfz-heidelberg.de/spec/lox-db/

Database Management Systems↗

PubMed2003

Multiple malformations in a male and maternal osteopathia strata with cranial sclerosis (OSCS).

Osteopathia striata with cranial sclerosis (OSCS), conductive hearing impairment and a characteristic facial appearance is the clinical manifestation in carrier women of an X-linked disease. We report on a family with typical OSCS in the mother, a maternal aunt and the grandmother, and multiple severe malformations in the son. He was affected by cranial sclerosis with frontal bossing, conductive hearing impairment, cleft palate, thoracic dysplasia, mesenterium commune with non-rotation of the gut, anal atresia, bilateral cutaneous syndactyly of 3rd and 4th fingers, duplication of the distal phalanx of 2nd and 3rd fingers on the right, bilateral fibular aplasia with clubfeet, developmental retardation, epileptic seizures, hypothyroidism, and hypertrophic pyloric stenosis. The X-inactivation pattern in peripheral leucocytes of one informative carrier woman was random. Our case and several literature reports confirm that males which are hemizygous for the OSCS trait suffer from a dysmorphic syndrome with characteristic multiple malformations as a distinct entity. There is, at present, no reason to assume genetic heterogeneity with an autosomal dominant OSCS variant.

Abnormalities, Multiple↗

PubMed2001

A gene cluster encoding human epidermis-type lipoxygenases at chromosome 17p13.1: cloning, physical mapping, and expression.

Epidermis-type lipoxygenases, a distinct subclass within the multigene family of mammalian lipoxygenases (LOX), comprise recently discovered novel isoenzymes isolated from human and mouse skin including human 15-LOX-2, human and mouse 12R-LOX, mouse 8S-LOX, and mouse e-LOX-3. We have isolated the human homologue of mouse e-LOX-3. The cDNA of 3362 bp encodes a 711-amino-acid protein displaying 89% sequence identity with the mouse protein and exhibiting the same unusual structural feature, i.e., an extra segment of 41 amino acids, which can be located beyond the N-terminal beta-barrel domain at the surface of the C-terminal catalytic domain. The gene encoding e-LOX-3, ALOXE3, was found to be part of a gene cluster of approximately 100 kb on human chromosome 17p13.1 containing in addition the 12R-LOX gene, ALOX12B, the 15-LOX-2 gene, ALOX15B, and a novel 15-LOX pseudogene, ALOX15P. ALOXE3 and ALOX12B are arranged in a head-to-tail fashion separated by 8.5 kb. The genes are split into 15 exons and 14 introns spanning 22 and 15 kb, respectively. ALOX15P was found on the opposite DNA strand directly adjacent to the 3'-untranslated region of ALOX12B. ALOX15B is located in the same orientation 25 kb downstream of ALOX12B, and is composed of 14 exons and 13 introns spanning a total of 9.7 kb of genomic sequence. RT-PCR analysis demonstrated a predominant expression of ALOXE3, ALOX12B, and ALOX15B in skin.

Amino Acid Sequence↗

PubMed2001

Enzymic characterization of epidermis-derived 12-lipoxygenase isoenzymes.

Substrate selectivity and other enzymic characteristics of two epidermis-derived lipoxygenases (LOXs), the epidermis-type (e) (12S)-LOX and (12R)-LOX, were compared with those of the platelet-type (p) (12S)-LOX. In contrast with p(12S)-LOX, e(12S)-LOX and (12R)-LOX exhibited no or very low reactivity towards the customary substrates linoleic acid and arachidonic acid but metabolized the corresponding fatty acid methyl esters, which, in contrast, were not accepted as substrates by p(12S)-LOX. Other esters of arachidonic acid and linoleic acid, including propan-2-yl and cholesterol esters, 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine, 1-palmitoyl-2-linoleyl-sn-glycero-3-phosphoethanolamine, and ceramide 1 carrying an omega-linoleic acid ester, were not metabolized by these three LOX isoenzymes. Among various polyunsaturated fatty acids the isomeric eicosatrienoic acids were found to be oxygenated by e(12S)-LOX but not by (12R)-LOX. 4,7,10,13,16,19-Docosahexaenoic acid as a substrate was restricted to p(12S)-LOX. Variations in the pH and the Ca(2+) content of the incubation medium affected the catalytic potential only slightly. Whereas (12R)-LOX activity increased in the presence of Ca(2+) and with an acidic pH, Ca(2+) had no effect on p(12S)-LOX and e(12S)-LOX; an acidic pH decreased the catalytic activity of the latter two. However, the catalytic activity of the epidermis-type isoenzymes, but not of p(12S)-LOX, was found to be markedly increased in the presence of DMSO. Under these conditions, e(12S)-LOX and (12R)-LOX oxygenated 4,7,10,13,16,19-docosahexaenoic acid to 14-hydroxy-4,7,10,12,16,19-docosahexaenoic acid and 13-hydroxy-4,7,10,14,16,19-docosahexaenoic acid respectively. In addition, (9R)-hydroxyoctadeca-10,12-dienoic acid methyl ester was generated from linoleic acid methyl ester by (12R)-LOX. Independently of the substrate, the catalytic activity of e(12S)-LOX and (12R)-LOX was always at most 2% of that of p(12S)-LOX with arachidonic acid as substrate.

Animals↗

PubMed2000

Positional- and stereo-selectivity of fatty acid oxygenation catalysed by mouse (12S)-lipoxygenase isoenzymes.

A quantitative stereochemical analysis of the products generated by recombinant mouse (12S)-lipoxygenase isoenzymes was performed with arachidonic acid and linoleic acid as substrates. The leucocyte-type (12S)-lipoxygenase generated, in addition to 12-hydroxyeicosatetraenoic acid (12-HETE) as the main product, 15- and 8-HETE from arachidonic acid and 13- and 9-hydroxyoctadecadienoic acid (13- and 9-HODE) from linoleic acid. The platelet-type enzyme oxygenated arachidonic acid to 12- and 8-HETE and linoleic acid to 13- and 9-HODE, whereas the epidermis-type (12S)-lipoxygenase reaction was essentially mono-specific with arachidonic acid but oxygenated linoleic acid to both 13- and 9-HODE. 12-HETE and 13-HODE were almost exclusively the S enantiomers. 8-HETE was the R enantiomer as a side-product of the platelet-type (12S)-lipoxygenase reaction but the S enantiomer as a side-product of the leucocyte-type reaction. 9-HODE was generated as the R enantiomer by the platelet-type and the epidermis-type isoenzymes and as the S enantiomer by the leucocyte-type (12S)-lipoxygenase. On the basis of published models of lipoxygenase-substrate interaction, the stereochemistry of the products generated by the platelet- and epidermis-type (12S)-lipoxygenases is in agreement with a fixed 'tail-to-head' orientation of the substrate fatty acid in the binding pocket of these enzymes, whereas that of the reaction products of the leucocyte-type (12S)-lipoxygenase can be explained only when the inverse orientation of the substrate or a rotational isomerism along the longitudinal axis of the substrate is allowed. Both the product spectra generated and the sensitivity towards the 12-lipoxygenase selective inhibitors N-benzyl-N-hydroxy-4-phenylpentanamide and cinnamyl-3,4-dihydroxy-alpha-cyanocinnamate indicated the platelet-type and the epidermis-type isoenzymes to be biochemically more related to each other than to the leucocyte-type (12S)-lipoxygenase.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed2000

Diversity of mouse lipoxygenases: identification of a subfamily of epidermal isozymes exhibiting a differentiation-dependent mRNA expression pattern.

By using reverse transcription-polymerase chain reaction technology (RT-PCR) and Northern blot analysis, the tissue-specific mRNA expression patterns of seven mouse lipoxygenases (LOX)--including 5S-, 8S-, three isoforms of 12S-, 12R-LOX, and a LOX of an as-of-yet unknown specificity, epidermis-type LOX-3 (e-LOX-3)--were investigated in NMRI mice. Among the various tissues tested epidermis and forestomach were found to express the broadest spectrum of LOX. With the exception of 5S- and platelet-type 12S-LOX (p12S-LOX) the remaining LOX showed a preference to exclusive expression in stratifying epithelia of the mouse, in particular the integumental epidermis. The expression of the individual LOX in mouse epidermis was found to depend on the state of terminal differentiation of the keratinocytes. mRNA of epidermis-type 12S-LOX (e12S-LOX) was detected in all layers of neonatal and adult NMRI mouse skin, whereas expression of p12S-LOX, 12R-LOX, and e-LOX-3 was restricted to suprabasal epidermal layers of neonatal and adult mice. 8S-LOX mRNA showed a body-site-dependent expression in that it was detected in stratifying epithelia of footsole and forestomach but not in back skin epidermis. In the latter, 8S-LOX mRNA was strongly induced upon treatment with phorbol esters. With the exception of e12S-LOX and p12S-LOX, the isozymes that are preferentially expressed in stratifying epithelia are structurally related and may be grouped together into a distinct subgroup of epidermis-type LOX.

Aging↗

PubMed2000

Expression of PGF(2alpha) receptor mRNA in normal, hyperplastic and neoplastic skin.

Reverse transcription polymerase chain reaction (RT-PCR) and Northern blot analysis was used to determine the level of expression of prostaglandin F(2alpha) (FP) receptor mRNA in various mouse tissues, including normal, hyperplastic and neoplastic mouse epidermis. Steady-state concentrations of FP receptor mRNA were low in normal and hyperplastic epidermis. The response of the epidermis to the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) was biphasic in that FP receptor mRNA was increased immediately after treatment, followed by a long-lasting down-regulation at later time points. FP receptor mRNA was down-regulated in the majority of papillomas obtained by the mouse skin carcinogenesis initiation-promotion protocol. In carcinomas, FP receptor mRNA expression was similar to that in normal epidermis. The steady-state concentration of FP mRNA was inversely correlated with PGF(2alpha) levels in normal and hyperplastic epidermis and in papillomas, indicating that FP mRNA expression is regulated by this eicosanoid.

Adolescent↗

PubMed1999

Prostaglandin-H-synthase isozyme expression in normal and neoplastic human skin.

Expression of prostaglandin-H-synthase (PGHS) isozymes was analyzed in 50 biopsies of normal human skin and of pre-malignant and malignant skin lesions, by means of quantitative RT-PCR, immunoprecipitation and Western blotting, as well as immunohistochemistry. Normal skin constitutively expressed PGHS-1 in all cell layers of the epidermis, in endothelial cells of small blood vessels and in sweat-gland epithelium. PGHS-2 expression was very low and restricted to a few keratinocytes of the interfollicular and follicular epidermis. Steady-state concentrations of PGHS-1 and PGHS-2 mRNA were similar in normal skin and in basal-cell carcinomas, but PGHS-1 mRNA was reduced and PGHS-2 mRNA was elevated in actinic keratoses, squamous-cell carcinomas and keratoacanthomas. PGHS-1 protein was detected in all tumor biopsies, being occasionally increased in basal-cell carcinomas. High amounts of PGHS-2 protein were found in actinic keratoses, squamous-cell carcinomas and keratoacanthomas, but not in basal-cell carcinomas. Four malignant melanomas included in this study contained PGHS-1 but no PGHS-2 protein. Immunohistochemical analysis of the biopsies identified keratinocytes, in addition to cells of inflammatory infiltrates and of dendritic morphology, as the major PGHS-expressing cell types. PGHS-2-specific signals were spread throughout the epidermal part of actinic keratoses and squamous-cell carcinomas. These data suggest that constitutive up-regulation of PGHS-2 expression is a consistent pre-malignant event in squamous-cell cancer development in man, as it is in animal models of skin carcinogenesis. Thus, pre-cancerous lesions such as actinic keratoses present a likely target for chemoprevention of skin cancer by selective PGHS-2 inhibitors.

Aged↗

PubMed1999

cDNA cloning, genomic structure, and chromosomal localization of a novel murine epidermis-type lipoxygenase.

Using a combination of degenerate PCR technique and conventional screening procedures, we isolated a cDNA encoding a novel lipoxygenase, termed epidermis-type lipoxygenase-3 (e-LOX-3, gene symbol Aloxe3), from mouse skin. Aloxe3 mRNA is expressed in the stratified epithelia of skin, tongue, and forestomach. The cDNA encodes a protein of 711 amino acids with a calculated molecular mass of 80.6 kDa. The amino acid sequence shows approximately 54% identity to the recently identified 12(R)-lipoxygenase. Sequence comparison revealed a segment of 41 amino acid residues localized near the boundary between the N- and the C-terminal domain sequences of the molecule, a structural feature that is also characteristic of 12(R)-lipoxygenase, suggesting that these two epidermis-derived lipoxygenases may be members of a novel structural class of mammalian lipoxygenases. The novel lipoxygenase gene is divided into 15 exons and 14 introns, spanning 22.3 kb of genomic DNA. By interspecific backcross analysis, the novel gene was localized to the central region of mouse chromosome 11.

Amino Acid Sequence↗

PubMed1999

Murine 12(R)-lipoxygenase: functional expression, genomic structure and chromosomal localization.

A cDNA, recently cloned (by Krieg et al. (1998)) from mouse skin, was shown to encode a 12(R)-lipoxygenase. When expressed in HEK cells, the recombinant protein converted methyl arachidonate into the corresponding 12-HETE ester which was shown to be the R-enantiomer by chiral phase chromatography. Neither arachidonic acid nor linoleic acid were substrates for the recombinant protein. The structure of the 12(R)-lipoxygenase gene is unique among all animal lipoxygenases in that it is divided into 15 exons and 14 introns spanning approximately 12.5 kb. By interspecific backcross analysis, the 12(R)-lipoxygenase gene was localized to the central region of mouse chromosome 11.

Animals↗

PubMed1999

Constitutive expression of 8-lipoxygenase in papillomas and clastogenic effects of lipoxygenase-derived arachidonic acid metabolites in keratinocytes.

The expression pattern, enzymatic activity, and products of 8-lipoxygenase (LOX) were analyzed in normal and neoplastic skin of NMRI mice. While barely detectable in normal epidermis, 8-LOX was transiently induced by 12-O-tetradecanoylphorbol-13-acetate and constitutively expressed in papillomas but not carcinomas obtained by the initiation-promotion protocol of mouse skin carcinogenesis. The product profile and chirality of both the native and the recombinant protein produced the S enantiomers of 8-hydroxy-5Z,9E,11Z,14Z-eicosatetraenoic acid (8-HETE) and 9-hydroxy-10E,12Z-octadecadienoic acid (9-HODE) as the main arachidonic acid- and linoleic acid-derived metabolites. As compared with normal epidermis, papillomas exhibited 25- and 4-fold elevated levels of 8-HETE and 9-HODE, respectively. However, the varying S to R ratios of 8-HETE and the predominance of 9(R)-HODE indicated that in addition to 8(S)-LOX, other enzymes yet to be defined may be involved in 8-HETE and 9-HODE production. The massive accumulation of both 8-HETE and 12-hydroxy-5Z,8Z,10E,14Z-eicosatetraenoic acid (12-HETE) point to a critical role of these LOX pathways in epidermal tumor development, in particular in the papilloma stage. Here we showed that 8- and 12-hydroperoxyeicosatetraenoic acids and 8- and 12-HETE induce chromosomal alterations in cycling primary basal keratinocytes.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed1999

Valve-sparing repair after aortic root dissection following heart transplantation.

We describe the case of a 56-year-old male who presented with a Stanford type A dissection limited to the donor aorta 25 days after orthotopic heart transplantation. Transesophageal echocardiography revealed a newly developed aortic regurgitation grade III and a typical intimal tear 1 cm above the commissures. Surgical therapy included replacement of the ascending aorta with an aortic allograft and implantation of the native aortic valve inside the allograft as a modified David procedure.

Aortic Dissection↗

PubMed1998

cDNA cloning of a 8-lipoxygenase and a novel epidermis-type lipoxygenase from phorbol ester-treated mouse skin.

Using a combination of PCR cloning and conventional screening procedures, we isolated from phorbol ester-treated mouse epidermis two full length cDNA clones encoding novel lipoxygenases. One of the cDNAs turned out to be identical to the recently cloned 8-lipoxygenase [Jisaka et al., J. Biol. Chem. 272 (1997) 24 410-24 416], the open reading frame of the second one corresponded to a protein of 701 amino acids with a calculated molecular mass of 80.6 kDa. The amino acid sequence showed 50.8% identity to human 15-lipoxygenase 2, approximately 40% to 5-lipoxygenase and 35% to 12- and 15-lipoxygenases. A unique structural feature is the insertion of 31 amino acid residues in the amino-terminal part of the molecule. Based on these data, we conclude that this epidermis-derived cDNA encodes a novel lipoxygenase isoform termed provisionally epidermis-type lipoxygenase 2 (e-LOX 2).

Amino Acid Sequence↗

PubMed1998

Inhaled nitric oxide and inhaled prostaglandin E1: effect on left ventricular contractility when used for treatment of experimental pulmonary hypertension.

OBJECTIVE: Pulmonary hypertension (PHT) is a life-threatening complication after isolated heart and lung transplantation. Recent work has shown that inhaled nitric oxide (NO) in combination with inhaled prostaglandin E1 (PGE1) reduce pulmonary hypertension but their influence on cardiac contractility is less well defined. METHODS: This study investigated left ventricular contractility as measured by the 'Preload Recruitable Stroke Work-Relation' (PRSW) in 24 anesthetized open chest pigs, 12 receiving in random order NO (50 ppm), PGE1 (20 microg/ml) and their combination compared to 12 controls. PHT was induced by embolization with glass beads (500 microm). Prior to induction of PHT, sonomicrometric crystals were placed on the heart to measure instantaneous cardiac dimensions. Instantaneous intraventricular pressure (micro-tip catheter) and intraventricular dimensions were recorded digitally, while intraventricular volumes were calculated from the intraventricular dimensions applying the cylindric ellipsoidal volume model for the left ventricle. PRSW was calculated from the instantaneous pressure and volume data during rapid vena caval occlusion by analysis of generated pressure-volume loops. All data were analyzed by MANOVA and corrected for heart rate (level of significance #: P < 0.05); PRSW-slope measures contractility, (PRSW-X-intercept did not change significantly). RESULTS: PRSW-change +/- SEM (in percent of initial PRSW after induction of PHT) was -14.6% +/- 4.4% versus 1.6% +/- 4.4% for NO versus Control (P = 0.004), -8.8% +/- 4.6% versus 1% +/- 3.3% (P = 0.18) for PGE1 versus Control and -5.7% +/- 4.4% versus 2.5% +/- 4.2% for NO + PGE1 versus Control (P = 0.33), respectively. In summary, application of NO 50 ppm significantly reduced left ventricular contractility while PGE1 20 microg/ml and the combination of NO and PGE1 did not. CONCLUSION: If NO is not available, the sole application of nebulized PGE1 (20 microg/ml) appears to be safe with respect to left ventricular contractility in the setting of PHT. The combination of NO and PGE1 for the treatment of pulmonary hypertension should be considered for clinical application in situations where a combination of pulmonary hypertension and decreased left ventricular function is present.

Administration, Inhalation↗

PubMed1998

Monitoring of respiratory function before and after cardiopulmonary bypass using side-stream spirometry.

Pulmonary impairment is more frequent after cardiac surgery than after other major surgical procedures. The present study investigates whether, by using standard respiratory monitoring, i.e. side-stream spirometry and blood gas analysis, it is possible to detect changes in pulmonary function secondary to cardiopulmonary bypass. We investigated 18 patients undergoing elective coronary bypass surgery or aortic valve replacement. Cardiopulmonary bypass resulted in a nonsignificant increase in alveolar-arterial oxygen difference from 33.0 +/- 10.6 kPa to 36.1 +/- 12.5 kPa and arterial to end-tidal CO2 tension difference from 0.67 +/- 0.39 kPa to 0.79 +/- 0.54 kPa. Respiratory system resistance was unaltered. In contrast, dynamic compliance decreased significantly after cardiopulmonary bypass from 78.6 +/- 22.9 to 65.4 +/- 22.4 mL cmH2O-1 with open chest and from 61.0 +/- 10.2 to 51.1 +/- 17.2 mL cmH2O-1 with closed chest, compared with corresponding values before cardiopulmonary bypass. In conclusion, pulmonary gas exchange was not compromised after cardiopulmonary bypass, but a diminished respiratory compliance was a consistent finding, even in uncomplicated cardiac surgery using routine respiratory monitoring.

Aged↗

PubMed1997

Repetin (Rptn), a new member of the "fused gene" subgroup within the S100 gene family encoding a murine epidermal differentiation protein.

We report the cloning and characterization of a murine epidermal differentiation gene, repetin (Rptn), exhibiting striking similarity to the genes of the intermediate filament-associated proteins profilaggrin and trichohyalin. The repetin gene consists of three exons and two introns. The first exon is short and untranslated. The deduced amino acid sequence distributed between exons II and III contains 1130 amino acids with a calculated molecular mass of 130 kDa and pI of 7.7. The amino terminus exhibits significant homology to the S100 proteins containing two calcium-binding motifs of the EF-hand type. The remainder coding sequence contains a central segment consisting of 49 tandem repeats of a 12-amino-acid sequence rich in glutamines. By fluorescence in situ hybridization the repetin gene was localized to chromosome band 3 F1-2. Expression of repetin mRNA is detectable in the stratified internal epithelia of forestomach and tongue and to a lesser degree in normal skin epidermis, where it is restricted to the differentiated suprabasal cell layers. Based on its chromosomal localization, its genomic organization, and its stage-specific expression during late epidermal differentiation, as well as on the structural features of the encoded protein, we conclude that the repetin gene represents a novel member of the "fused gene" subgroup of the S100 gene family encoding multifunctional epidermal matrix proteins.

Amino Acid Sequence↗