Changes in the distribution of intermediate filament proteins and collagen IV in fetal and adult human pancreas. I. Localization of cytokeratin polypeptides

The expression patterns of individual cytokeratin polypeptides in foetal and adult human pancreatic tissues were examined using monoclonal antibodies. We demonstrated that human pancreatic epithelia in early stages of development (14 weeks of gestation) contain cytokeratins 7, 8, 18 and 19, which are typical of simple epithelia, as well as cytokeratin 4 and 17, which are characteristic of stratified epithelia. In the pancreatic ducts, most of these cytokeratins appeared to be expressed together. Cytokeratins 1, 5, 10, 13, 16 and 20 were not detectable. In contrast, the pancreatic parenchyma was only positive for cytokeratins 8 and 18, except a transient expression of cytokeratins 7 and 19 in pancreatic islets and acinar cells during the foetal development. A focal cytokeratin 7 staining of single acinar cells was seen in newborn and in adult islets. In the stromal tissue, vascular smooth muscle cells were partly reactive with cytokeratin 8 and 18 specific antibodies. The results are discussed in the light of differentiation-dependent changes in the expression of individual cytokeratin polypeptides in developing epithelia.     

Changes in the Pattern of Cytokeratin Polypeptides in Epidermis and Hair Follicles During Skin Development in Human Fetuses

Abstract. The cytokeratin polypeptides of microdissected epidermis and hair follicles from human fetuses (from week 10 of pregnancy until birth) have been analysed by two-dimensional gel electrophoresis. Two-layered epidermis in 10-week fetuses contains major amounts of cytokeratin polypeptides typical of simple epithelia (components Nos. 8, 18, and 19 according to Moll et al. [31]). These cytokeratins are gradually reduced in their relative amounts and eventually disappear in the multilayered epidermis of later stages. At advanced stages of development, cytokeratins characteristic of adult epidermis are detected and finally predominate. These include the large and basic epidermal cytokeratin No. 1 (apparent molecular weight 68,000) which is already present in the three-layered epidermis of 13-week fetuses. Hair follicle germ cells of 13-week fetuses differ from fetal epidermal keratinocytes and show a very simple cytokeratin pattern, dominated by only two major polypeptides (Nos. 5 and 17). More developed hair follicles of 20-week fetuses have established a cytokeratin pattern similar to, but not identical with, that of hair follicles from adult skin. Different staining patterns obtained by indirect immunofluorescence microscopy using cytokeratin antibodies with different specificities suggest that, in three-layered epidermis, different cytokeratin patterns might exist in the specific cell layers. Such a differential location might explain the high complexity of polypeptide components found in fetal skin. Possible contributions of peridermal cytokeratins to this complex pattern of fetal epidermis are discussed.     

Cytokeratin expression in human thymus: immunohistochemical mapping

Cytokeratin expression in normal postnatal human thymus was studied immunohistochemically by using monoclonal antibodies against various cytokeratin polypeptides. An attempt was made to characterize cell populations giving rise to the cornified structures of Hassal's corpuscles. Monoclonal antibody KB-37, a marker of squamous epithelium basal cells, was applied to distinguish the earliest cells capable of undergoing squamous differentiation. Parts of the subcapsular epithelium were extensively stained with this reagent. This epithelium, like the basal layer of certain squamous epithelia, exibited a high incidence of cytokeratins 13 and 14, and pronounced expression of cytokeratin 19. Simple epithelium cytokeratins 8, 18, and 19 were present in the cortex. Scattered cells reacted with KB-37 antibody. All stellate epithelial cells in the medulla were positive for cytokeratin 19. Most of the medullar epithelial cells were positive for cytokeratins 13, 14 and 17 of complex epithelium, in contrast to the cortex, where only a few cells were positive for these cytokeratins. A significant proportion of the medullar cells was positive for KB-37 antigen. Cytokeratins 8 and 18 were expressed in single cells and in groups of cells surrounding Hassal's corpuscles. The outermost cells of these corpuscles were positive for cytokeratin 19 and KB-37. In the peripheral parts of Hassal's corpuscles, simple epithelium cytokeratins 7, 8, 18, and cytokeratins 4, 13, 14, and 17, characteristic of stratified nonkeratinizing epithelia, were coexpressed with keratinization-specific cytokeratins 10/11. The inner parts of the swirls were uniformly positive for cytokeratins was reduced.     

Proliferation of human embryonic and fetal epidermal cells in organ culture

The morphology of human embryonic and fetal skin growth in organ culture at the air-medium interface was examined, and the labeling indices of the epidermal cells in such cultures were determined. The two-layered epidermis of embryonic specimens increased to five or six cell layers after 21 days in culture, and the periderm in such cultures changed from a flat cell type to one with many blebs. The organelles in the epidermal cells remained unchanged. Fetal epidermis, however, differentiated when grown in this organ culture system from three layers (basal, intermediate, and periderm) to an adult-type epidermis with basal, spinous, granular, and cornified cell layers. Keratohyalin granules, lamellar granules, and bundles of keratin filaments, organelles associated with epidermal cell differentiation, were observed in the suprabasal cells of such cultures. The periderm in these fetal cultures formed blebs early but was sloughed with the stratum corneum in older cultures. The rate of differentiation of the fetal epidermis in organ culture was related to the initial age of the specimen cultured, with the older specimens differentiating at a faster rate than the younger specimens. Labeling indices (LIs) of embryonic and fetal epidermis and periderm were determined. The LI for embryonic basal cells was 8.5% and for periderm was 8%. The fetal LIs were 7% for basal cells, 1% for intermediate cells, and 3% for periderm. The ability to maintain viable pieces of skin in organ culture affords a model for studying normal and abnormal human epidermal differentiation from fetal biopsies and for investigating proliferative diseases.     

Expression of intermediate-sized filaments in developing and adult human kidney and in renal cell carcinoma.

We studied the distribution of intermediate-sized filaments in developing and adult kidneys and renal cell carcinoma (RCC) by indirect immunohistochemistry, using a pan-cytokeratin mouse monoclonal antibody (MAb), chain-specific anti-cytokeratin MAb, and anti-vimentin and anti-desmin MAb, to resolve controversy concerning intermediate-sized filament expression in the kidney. With the pan-cytokeratin MAb, cytokeratin expression was detectable in all stages of nephron development, starting with expression in the renal vesicles, the progenitors of the glomeruli, proximal tubules, Henle's loop, and part of the distal tubules. Using chain-specific anti-cytokeratin MAb, cytokeratin 8 and 18 expression was demonstrated in all developmental structures of the nephron, whereas cytokeratin 19 expression was more complex. None of the nephrogenic blastema cells from which the renal vesicles arise expressed cytokeratins. Transient expression of vimentin and cytokeratin 19 was observed in differentiating collecting ducts and proximal tubule cells at the S-shaped stage of nephron development, respectively. In RCC, cytokeratin expression closely resembled that of the mature proximal tubule, i.e., RCC cells expressed cytokeratins 8 and 18. However, in a subset of RCC additional cytokeratin 19 expression was noted. In addition, all except one RCC showed co-expression of cytokeratins and vimentin.     

Changes in cytokeratin expression in epidermal keratinocytes during wound healing

In order to investigate the re-epithelialization process during wound healing, the hair on the back of guinea pigs was shaved and then excisional wounds were made through the entire thickness of the skin. Histological changes were observed and changes in the expression of different cytokeratin polypeptides were examined using an immunohistochemical technique. Immunohisto chemical study revealed that the proliferating and migrating keratinocytes expressed the same cytokeratins as the basal cells of normal epidermis. In addition, the entire epidermis of fairly remote areas from the edges of the wound where no thickening was observed showed a temporarily abnormal staining pattern. The suprabasal cells in the regenerating epidermis temporarily expressed cytokeratins not only specific for suprabasal cells but also specific for basal cells. The cytokeratins expressed in normal basal keratinocytes were also present in the thickened granular layers. These data indicate that the expression of cytokeratins in the epidermal keratinocytes (even in fairly remote areas from the wound edges) changes during wound healing, that the origin of the migrating keratinocytes from the remaining epidermis seems to be the basal cells in the epidermis, and that the appearance of keratohyalin granules is not related to changes in cytokeratin expression.     

Changes in the distribution of intermediate filament proteins and collagen IV in fetal and adult human pancreas

Summary The expression patterns of individual cytokeratin polypeptides in foetal and adult human pancreatic tissues were examined using monoclonal antibodies. We demonstrated that human pancreatic epithelia in early stages of development (14 weeks of gestation) contain cytokeratins 7, 8, 18 and 19, which are typical of simple epithelia, as well as cytokeratin 4 and 17, which are characteristic of stratified epithelia. In the pancreatic ducts, most of these cytokeratins appeared to be expressed together. Cytokeratins 1, 5, 10, 13, 16 and 20 were not detectable. In contrast, the pancreatic parenchyma was only positive for cytokeratins 8 and 18, except a transient expression of cytokeratins 7 and 19 in pancreatic islets and acinar cells during the foetal development. A focal cytokeratin 7 staining of single acinar cells was seen in newborn and in adult islets. In the stromal tissue, vascular smooth muscle cells were partly reactive with cytokeratin 8 and 18 specific antibodies. The results are discussed in the light of differentiation-dependent changes in the expression of individual cytokeratin polypeptides in developing epithelia.     

Expression of intermediate filament proteins in fetal and adult human lung tissues

The expression patterns of intermediate filament proteins in fetal and normal or nonpathological adult human lung tissues are described using (chain-specific) monoclonal antibodies. In early stages of development (9-10 weeks and 25 weeks of gestation) only so-called simple cytokeratins such as cytokeratins 7 (minor amounts). 8, 18 and 19 are detected in bronchial epithelial cells. At later stages of development, the cytokeratin expression patterns become more complex. The number of bronchial cells positive for cytokeratin 7 increases, but basal cells in the bronchial epithelium remain negative. These latter cells show, however, expression of cytokeratin 14 in the third trimester of gestation. Developing alveolar epithelial cells express cytokeratins 7, 8, 18 and 19. In adult human bronchial epithelium cytokeratins 4 (varying amounts), 7, 8, 13 (minor amounts), 14, 18 and 19 can be detected, with the main expression of cytokeratins 7, 8, and 18 in columnar cells and the main expression of cytokeratin 14 in basal cells. Vimentin is detected in all mesenchymal tissues. In addition, fetal lung expresses vimentin in bronchial epithelium, however, to a lesser extent with increasing age, resulting in the expression of vimentin in only few scattered bronchial cells at birth. Also in adult bronchial epithelium the expression of vimentin is noticed in part of the basal and columnar epithelial cells. Desmin filaments, present in smooth muscle cells of the lung, appear to alter their protein structure with age. In early stages of development smooth muscle cells surrounding blood vessels are partly reactive with some cytokeratin antibodies and with a polyclonal desmin antibody. At week 9-10 and week 25 of gestation a monoclonal antibody to desmin, however, is not reactive with blood vessel smooth muscle cells but is only reactive with smooth muscle cells surrounding bronchi. With increasing age the reactivity of cytokeratin antibodies with smooth muscle cells in blood vessels decreases, while the reactivity with the monoclonal desmin antibody increases. Our results show that during differentiation profound changes in the intermediate filament expression patterns occur in the different cell types of the developing lung.     

The pattern of cytokeratin synthesis is a marker of type 2 cell differentiation in adult and maturing fetal lung alveolar cells

During the last stages of fetal life, the immature epithelial cells of the rat lung alveolus develop the properties of mature type 2 cells. Adult type 2 cells rapidly lose these same properties when isolated and maintained in cell culture. We have examined the synthesis of cytokeratin proteins by adult type 2 cells as they lose their differentiated characteristics during 1 week in culture, and of immature fetal alveolar epithelial cells as they differentiate either in utero or when cultured on an extracellular matrix. Freshly isolated adult type 2 cells synthesize four cytokeratins which by electrophoretic mobilities and Western blot analysis correspond to human cytokeratins Nos. 7, 8, 18, and 19. During 7 days in culture synthesis of cytokeratin No. 19 is dramatically decreased and cytokeratin No. 18 becomes the predominant acidic cytokeratin produced. Fetal lung epithelial cells at 18 days gestation lack most characteristics of mature type 2 cells. When freshly isolated, these cells synthesize cytokeratins Nos. 7, 8, and 18 but make only minimal amounts of cytokeratin No. 19. When these cells are allowed to mature either in utero or in culture on a whole basement membrane extract, they develop both the morphological characteristics and the pattern of cytokeratin synthesis of fully developed type 2 cells, with cytokeratins No. 19 being the major acidic cytokeratin produced.     

PTHrP and cytokeratins in human epidermis

We have demonstrated the presence of parathyroid hormone-related peptide (PTHrP) in cells of human epidermis, employing immunocytochemical techniques. Cells of human epidermal layers demonstrated variable intensity of the reaction. The least pronounced reaction was detected in cells of the basal and the most pronounced reaction in cells of the granular layer. Ultrastructural studies demonstrated that gold particles labeled bundles of keratin filaments. Therefore, at the subsequent stage of the studies we examined the type of filaments to which PTHrP was bound, using immunocytochemical reactions with antibodies against cytokeratins 10, 14, 16 and 19. Positive reaction was obtained for cytokeratins 10, 14 and 16. The reaction pattern obtained for cytokeratins 10 and 16 most closely resembled that of PTHrP. Double labeling with colloidal gold was performed at the ultrastructural level. The results obtained in this way demonstrated that PTHrP most probably binds to filaments built of cytokeratin 16. By binding to the cytokeratin, PTHrP may possibly affect growth and differentiation of keratinocytes.     

Synthesis of cytokeratin 13, a component characteristic of internal stratified epithelia, is not induced in human epidermal tumors

Human cytokeratin 13 is one of the most abundant intermediate filament (IF) proteins of many internal stratified epithelia and occurs, at least in certain cell cultures, in an O-glycosylated form binding the lectin, wheat germ agglutinin (WGA). As other groups have reported that, in the mouse, the synthesis of mRNA encoding the 47-kDa cytokeratin corresponding to human cytokeratin 13 is induced in epidermal keratinocytes during malignant transformation, we have examined the synthesis of cytokeratin 13 mRNA and protein in human epidermis and epidermal tumors, using specific cDNA probes and cytokeratin 13 antibodies. We isolated two different cDNA clones from the vulvar carcinoma cell line A-431, in which this protein is abundant: One clone seems to represent the entire mRNA, whereas the other is only a minor component and encodes a truncated cytokeratin 13 lacking most of the carboxy-terminal tail domain, probably a product of alternative, "incorrect" splicing. Comparison of the amino acid sequences with those of other cytokeratins revealed a high degree of conservation with respect to several other human type I cytokeratins, notably cytokeratin 15, and to the murine 47-kDa cytokeratin. When human epidermis and a series of benign and malignant epidermal tumors were examined with these cDNA probes and cytokeratin-13-specific antibodies we did not find an induction of expression in keratinocytes, normal or malignantly transformed, except for some scattered, sparse cytokeratin-13-positive cells and very low levels of cytokeratin 13 mRNA, detectable only with the highly sensitive polymerase chain reaction (PCR). We conclude that the gene(s) encoding cytokeratin 13 are not induced in human keratinocytes during epidermal carcinogenesis, in apparent contrast to reports of murine epidermal tumors, and we discuss possible explanations for this interspecies difference.     

Extensive changes in cytokeratin expression patterns in pathologically affected human gingiva

The stratified squamous epithelium of the oral gingiva and the hard palate is characterized by a tissue architecture and a cytoskeletal composition similar to, although not identical with, that of the epidermis and fundamentally different from that of the adjacent non-masticatory oral mucosa. Using immunocytochemistry with antibodies specific for individual cytokeratins, in situ hybridization and Northern blots of RNA with riboprobes specific for individual cytokeratin mRNAs, and gel electrophoresis of cytoskeletal proteins of microdissected biopsy tissue samples, we show changes in the pattern of expression of cytokeratins and their corresponding mRNAs in pathologically altered oral gingiva. Besides a frequently, although not consistently, observed increase in the number of cells producing cytokeratins 4 and 13 (which are normally found as abundant components in the sulcular epithelium and the alveolar mucosa but not in the oral gingiva) and a reduction in the number of cells producing cytokeratins 1, 10 and 11, the most extensive change was noted for cytokeratin 19, a frequent cytokeratin in diverse one-layered and complex epithelia. While in normal oral gingiva cytokeratin 19 is restricted to certain, sparsely scattered cells of --or near--the basal cell layer, probably neuroendocrine (Merkel) cells, in altered tissue of inflamed samples it can appear in larger regions of the basal cell layer(s) and, in apparently more advanced stages, also in a variable number of suprabasal cells. Specifically, our in situ hybridization experiments show that this altered suprabasal cytokeratin 19 expression is more extended at the mRNA than at the protein level, indicating that cytokeratin 19 mRNA synthesis may be a relatively early event during the alteration. These changes in cytokeratin expression under an external pathological influence are discussed in relation to other factors known to contribute to the expression of certain cytokeratins and with respect to changes occurring during dysplasia and malignant transformation of oral epithelia.     

Temporal and spatial sequence expression of cytokeratin K19 in cultured human keratinocyte

The unique cytokeratin K19 specifically expresses in simple epithelial cells, basal cells of non-keratinized stratified squamous epithelium, epidermal cells during the embryonic stage and squamous carcinoma cells, but it is not expressed in adult epidermis. Interestingly, when epidermal cells are cultured in vitro, K19 is re-expressed in the supra-basal layer. K19 expression was used as a marker for epidermal cell growth and differentiation. In order to clarify the temporal and spatial sequential expression in cultured keratinocyte, two-stage human keratinocyte culture systems were used to examine K19 expression in keratinocytes in a proliferation and differentiation stages through immunoblotting and immunohistochemistry assay. According to our results, K19 was not expressed in cultured human keratinocytes in the proliferation stage but was re-expressed in keratinocytes three days after the cultured medium was changed to a differentiation medium. Immunohistochemical observation revealed that K19 was persistently expressed in the supra-basal layer of cultured keratinocytes during first three weeks of culturing, but none was detectable in the basal cell layer. When keratinocytes were cultured with an "inserted cultured dish," K19 was persistently expressed in all layers of keratinocytes nourished by medium both from an inner chamber and an outer chamber. The different expression of K19 in these two different culture systems seemed to indicate that down regulation of K19 expression in keratinocyte was related to the direction of medium supply.     

Cytokeratin expression in human respiratory epithelium of nasal polyps and turbinates

The cytokertatins in respiratory epithelial cells (REC) of human nasal polyps and turbinates were analyzed by immunohistochemistry. Cytokeratin 19 (CK19) was present in all REC, CK5 and 14 were expressed primarily in basal cells, and CK7, 8, and 18 were found in suprabasal cells. Differences in cytoplasmic locations were also apparent among the individual cytokeratins. CK13 was not detected in any REC of these tissues. The results indicate the profile of cytokeratins in REC of human nasal polyps and turbinates is essentially identical to that of REC in the more distal respiratory tract.     

Cytokeratins in normal lung and lung carcinomas. I. Adenocarcinomas, squamous cell carcinomas and cultured cell lines

The various epithelial cells of the lower respiratory tract and the carcinomas derived from them differ markedly in their differentiation characteristics. Using immunofluorescence microscopy and two-dimensional gel electrophoresis of cytoskeletal proteins from microdissected tissues we have considered whether cytokeratin polypeptides can serve as markers of cell differentiation in epithelia from various parts of the human and bovine lower respiratory tract. In addition , we have compared these protein patterns with those found in the two commonest types of human lung carcinoma and in several cultured lung carcinoma cell lines. By immunofluorescence microscopy, broad spectrum antibodies to cytokeratins stain all epithelial cells of the respiratory tract, including basal, ciliated, goblet, and alveolar cells as well as all tumor cells of adenocarcinomas and squamous cell carcinomas. However, in contrast, selective cytokeratin antibodies reveal cell type-related differences. Basal cells of the bronchial epithelium react with antibodies raised against a specific epidermal keratin polypeptide but not with antibodies derived from cytokeratins characteristic of simple epithelia. When examined by two-dimensional gel electrophoresis, the alveolar cells of human lung show cytokeratin polypeptides typical of simple epithelia (nos. 7, 8, 18 and 19) whereas the bronchial epithelium expresses, in addition, basic cytokeratins (no. 5, small amounts of no. 6) as well as the acidic polypeptides nos. 15 and 17. Bovine alveolar cells also differ from cells of the tracheal epithelium by the absence of a basic cytokeratin polypeptide. All adenocarcinomas of the lung reveal a "simple-epithelium-type" cytokeratin pattern (nos. 7, 8, 18 and 19). In contrast, squamous cell carcinomas of the lung contain an unusual complexity of cytokeratins. We have consistently found polypeptides nos. 5, 6, 8, 13, 17, 18 and 19 and, in some cases, variable amounts of cytokeratins nos. 4, 14 and 15. Several established cell lines derived from human lung carcinomas (SK-LU-1, Calu -1, SK-MES-1 and A-549) show a uniform pattern of cytokeratin polypeptides (nos. 7, 8, 18 and 19), similar to that found in adenocarcinomas. In addition, vimentin filaments are produced in all the cell lines examined, except for SK-LU-1.(ABSTRACT TRUNCATED AT 400 WORDS)     

DNA synthesis and content in the nuclei of epidermal cells of mice during their differentiation and specialization

Synthesis and content of DNA in the nuclei of differentiating cells of mouse skin epidermis was studied by using cytomorphometric, autoradiographic and cytophotometric methods. It has been shown that the cells of the keratinoid series divide only in the basal layer and contain 2-4c DNA. Keratinocytes of the thorny layer are mostly tetraploid, 2c cells are lacking. H4c and 8c cells comprise 12% of the population. In the keratinocytes of the granular layer DNA content is somewhat lower due to nuclei break down and conversion of cells into anucleate scale. Part of the melanocytes of the basal layer also contain 4c DNA. Highly specialized element of the basal layer Merkel and Langerhans cells are polyploid. Conclusion is drawn that DNA hyper-replication by multiplication of the whole genome is part of the development program of the population.     

Identification of Merkel cells in human skin by specific cytokeratin antibodies:

Merkel cells are special neurosecretory cells which, in adult human skin, are usually very scarce. By immunofluorescence microscopy using antibodies to human cytokeratin polypeptide no. 18, we localized distinct non-keratinocyte cells in the glandular ridges of human fetal and adult plantar epidermis. Using electron and immunofluorescence microscopy, these cells were identified as Merkel cells containing typical neurosecretory granules as well as bundles of intermediate-sized filaments and desmosomes. Two-dimensional gel electrophoresis of the cytoskeletal fractions of microdissected epidermal preparations highly enriched in Merkel cells indicated the presence of cytokeratin polypeptides nos. 8, 18 and 19 which are typical of diverse simple epithelia of the human body. Double immunofluorescence microscopy showed that these human Merkel cells contain neither neurofilaments nor vimentin filaments. In human fetuses of 18-24 weeks of age, conspicuously high concentrations of Merkel cells, reaching a density of approximately 1,700 Merkel cells/mm2 skin, were found in the glandular ridges of plantar skin. The concentration decreased considerably at newborn and adult stages. Thin cell processes (up to 20 microns long) were observed in many fetal epidermal Merkel cells. In addition, we detected isolated Merkel cells deeper in the dermis (i.e. at distances of, at most, 100 microns from the epidermis) in fetal and newborn plantar skin. Our results show that Merkel cells are true epithelial cells which, however, differ profoundly from epidermal keratinocytes in their cytokeratin expression. The findings are discussed in relation to the much disputed question of the origin of Merkel cells. The present data speak against the immigration of Merkel cells from the neural crest, but rather suggest that they originate from epithelial cells of the skin, although most probably not from differentiated keratinocytes.     

Immunohistochemical markers of human sebaceous gland differentiation

Cryostat sections of human skin were stained with monoclonal antibodies to involucrin, a range of cytokeratins, epithelial membrane antigen (EMA), and an ovarian cystadenocarcinoma antibody (OM1) to identify combinations of antibodies that could be used to discriminate between basal and differentiated sebocytes and other cell types present in the pilosebaceous unit. Both the EMA and OM1 monoclonal antibodies specifically recognized differentiated sebocytes. No staining of basal sebocytes or other epidermal cell types was seen. Differentiated (but not basal) sebocytes were also stained by a cytokeratin 10 antibody (LH2). Conversely, the basal sebocytes were recognized by an antibody specific to basal keratinocytes (LH6). Cells of the sebaceous duct stained with both LH2 and LH6 and also with the anti-involucrin monoclonal antibody. Cytokeratin 4 has been detected in sebaceous glands by protein analysis but has not previously been detectable immunohistochemically. We show by immunofluorescence after limited proteolysis that cytokeratin 4 epitopes are distributed in all sebaceous gland cells, including the duct cells.     

Different keratin polypeptides in epidermis and other epithelia of human skin: a specific cytokeratin of molecular weight 46,000 in epithelia of the pilosebaceous tract and basal cell epitheliomas

Cytokeratin polypeptides of human epidermis, of epithelia microdissected from various zones of the pilosebaceous tract (outer root-sheath of hair follicle, sebaceous gland), and of eccrine sweat-glands have been separated by one- and two-dimensional gel electrophoresis and characterized by binding of cytokeratin antibodies and by peptide mapping. The epithelium of the pilosebaceous tract has three major keratin polypeptides in common with interfollicular epidermis (two basic components of mol wts 58,000 and 56,000 and one acidic polypeptide of mol wt 50,000); however, it lacks basic keratin polypeptides in the mol wt range of 64,000-68,000 and two acidic keratin-polypeptides of mol wts 56,000 and 56,500 and contains an additional characteristic acidic cytokeratin of mol wt 46,000. Another cytokeratin polypeptide of mol wt 48,000 that is prominent in hair-follicle epithelium is also found in nonfollicular epidermis of foot sole. Both epidermis and pilosebaceous tract are different from eccrine sweat-gland epithelium, which also contains two major cytokeratins of mol wts 52,500 and 54,000 (isoelectric at pH 5.8-6.1) and a more acidic cytokeratin of mol wt 40,000. A striking similarity between the cytokeratins of human basal-cell epitheliomas and those of the pilosebaceous tract has been found: all three major cytokeratins (mol wts 58,000; 50,000; 46,000) of the tumor cells are also expressed in hair-follicle epithelium. The cytokeratin of mol wt 46,000, which is the most prominent acidic cytokeratin in this tumor, is related, by immunological and peptide map criteria, to the acidic keratin-polypeptides of mol wts 48,000 and 50,000, but represents a distinct keratin that is also found in other human tumor cells such as in solid adamantinomas and in cultured HeLa cells. The results show that the various epithelia present in skin, albeit in physical and ontogenic continuity, can be distinguished by their specific cytokeratin-polypeptide patterns and that the cytoskeleton of basal-cell epitheliomas is related to that of cells of the pilosebaceous tract.     

Co-localization of COX-2, CYP4F8, and mPGES-1 in epidermis with prominent expression of CYP4F8 mRNA in psoriatic lesions

Cyclooxygenase-2 (COX-2), cytochrome P450 4F8 (CYP4F8), and microsomal PGE synthase-1 (mPGES-1) form PGE and 19-hydroxy-PGE in human seminal vesicles. We have examined COX-2, CYP4F8, and mPGES-1 in normal skin and in psoriasis. All three enzymes were detected in epidermis by immunofluorescence and co-localized in the suprabasal cell layers. In lesional psoriasis the enzymes were also co-localized in the basal cell layers. Real-time RT-PCR analysis suggested that CYP4F8 mRNA was induced 15-fold in lesional compared to non-lesional epidermis. mRNA of all enzymes were present in cultured HEK and HaCaT cells, but the prominent induction of CYP4F8 mRNA in psoriasis could not be mimicked by treatment of these keratinocytes with a mixture of inflammatory cytokines or with phorbol 12-myristate-13-acetate. The function of CYP4F8 in epidermis might be related to lipid oxidation and keratinocyte proliferation.