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    Monospecific monoclonal antibodies to keratin 1 carboxy terminal (synthetic peptide) and to keratin 10 as markers of epidermal differentiation
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    Abstract:
    Monospecific antibodies to individual keratin polypeptides can be used to examine the tissue and cellular coexpression of members of keratin pairs. Monospecific monoclonal and polyclonal antibodies have been raised to keratins 1 and 10 using both crude cytoskeletal extracts and synthetic peptides. The tissue distribution of these keratins has been determined against a panel of freshly frozen normal tissues from humans, rodents and pigs. Epidermal expression has been examined in psoriatic plaques, and healing wounds, as examples of epidermal hyperproliferation. Cultured keratinocytes in monolayer (low calcium), stratified (high calcium), and complex cultures, transformed keratinocytes, and tumour cell lines, have been examined for the in vitro expression of these keratins. The sensitivity and precise localization of reactivity with these monospecific antibodies gives a highly accurate picture of individual cell expression. There is confirmation of coexpression of keratins 1 and 10 in epidermal and mucosal sites, and with keratin 16 in hyperproliferative states. These monospecific antibodies provide an important means of examining keratin expression in epidermal tumours and keratinizing disorders, and of seeking keratin mutations in cell lines and in skin diseases.
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    Keratin 7
    Keratin 8
    Cytokeratin pattern was analyzed in 14 moderately differentiated and 12 well‐differentiated squamous cell carcinomas of buccal mucosa by SDS‐PAGE, immunoblotting and two dimensional electrophoresis. These were compared with patterns of normal buccal mucosa and surrounding areas whenever possible. Normal buccal mucosa expresses keratin No. 4 (59Kd), 5 (58Kd), 13 (54Kd) and 14 (50Kd). Keratin No. 4 (59Kd) and 14 (50Kd) were expressed by 20 of 26 tumors studied, while many of the tumors did not express keratins No. 5 (58Kd) and 13 (54Kd). Keratin No. 1 (67Kd) and 16 (48Kd) were aberrantly expressed by 9 well‐differentiated tumors. Keratin No. 17 (46Kd) and 18 (45Kd) were expressed by 10 and 8 tumors of 14 moderately differentiated tumors. Six tumors which showed involvement of alveolar mucosa, expressed some keratins expressed by its normal counterpart. Their altered expression was consistent with the differentiation pattern as stated earlier. Non‐expression of keratins 5 and 13 seems to be the result of malignant transformation and is seen in the majority of tumors, while appearance of aberrant keratins seems to be related more to the degree of differentiation of the tumor.
    Keratin 8
    Keratin 7
    Buccal mucosa
    Keratin 5
    Malignant Transformation
    Keratin 6A
    Sakamoto K, Aragaki T, Morita K‐i, Kawachi H, Kayamori K, Nakanishi S, Omura K, Miki Y, Okada N, Katsube K‐i, Takizawa T & Yamaguchi A (2011) Histopathology 58, 531–542 Down‐regulation of keratin 4 and keratin 13 expression in oral squamous cell carcinoma and epithelial dysplasia: a clue for histopathogenesis Aims: This study aimed to identify relevant keratin subtypes that may associate with the pathogenesis of oral epithelial neoplasms. Methods and results: Expression of all the keratin subtypes was examined by cDNA microarray analysis of 43 oral squamous cell carcinoma (OSCC) cases. Immunohistochemical expression of the major keratins was examined in 100 OSCC and oral epithelial dysplasia (OED) cases. Many changes in keratin expression were observed and, significantly, consistent down‐regulation of keratin 4 (K4) and K13 expression was observed. Aberrant expression of K4 and K13 was associated with morphological changes in the affected oral epithelium. Experiments with cell cultures transfected with various keratin subtypes suggested that alterations in keratin subtype expression can cause changes in cell shape and movement. Conclusions: Aberrant expression of K4 and K13, which are the dominant pair of differentiation‐related keratins in oral keratinocytes, indicates dysregulation of epithelial differentiation in OSCC and OED. These keratins, especially K4, may be useful for pathological diagnosis. We propose that the aberrant expression of K4 and K13 and concomitant up‐regulation of the other keratins may be one of the causative factors for morphological alterations in the affected epithelium.
    Epithelial dysplasia
    Keratin 8
    Keratin 7
    Keratin 5
    Keratin 14
    We have investigated keratin expression in fetal, newborn and adult rat intestines by immunofluorescence staining, immunoblotting of two-dimensional gels and Northern blot analysis of total cellular RNAs. Keratin-type intermediate filaments, composed predominantly of keratin no. 19, were observed already in the undifferentiated stratified epithelium present at 15-16 days of gestation. The marked maturation and differentiation of the epithelium taking place at 18-19 days of gestation was characterized by the appearance of the differentiation-specific keratin no. 21 and by a significant increase in the relative amount of keratin no. 8. The keratin pattern typical of adult villus cells became established at the time of birth, and was marked by a considerable increase in the complexity of the keratin-related polypeptides detected on two-dimensional gels, indicative of extensive post-translational modification of all keratins. Starting at 20 days of gestation there was a major increase in the relative abundance of mRNAs coding for keratin nos. 8, 19 and 21; in contrast, the relative amount of keratin no. 18 mRNA reached a peak shortly after birth and declined to very low levels in adult intestine. These results demonstrated marked changes in keratin expression and post-translational processing taking place at key stages of intestinal development. The appearance of keratin no. 21 in coincidence with the formation of an adult-type brush border and terminal web would be consistent with it having an important role in the organization of the intermediate filament network in the apical cytoplasm of the differentiated intestinal cells.
    Keratin 7
    Keratin 8
    Keratin 6A
    Keratin 5
    Keratin 14
    Immunofluorescence
    Citations (22)
    The keratins 8 and 18 of simple epithelia differ from stratified epithelial keratins in tissue expression and regulation. To examine the specific properties of human keratin 8, we cloned and sequenced the cDNA from a placental mRNA expression library and defined the optimum state of such clones for expression in bacterial plasmid vectors. Using the polymerase chain reaction we identified and sequenced three introns and located the single active gene for keratin 8, out of a background of 9 to 24 pseudogenes, on chromosome 12. This chromosome contains several genes for type II keratins and also the gene for keratin 18, the type I keratin that is coexpressed with keratin 8. This location of both members of a keratin pair on a single chromosome is thus far unique among the keratin genes; it is consistent with the hypothesis that keratins 8 and 18 may be closer to an ancestral keratin gene than the keratins of more highly differentiated epithelia.
    Keratin 6A
    Keratin 7
    Keratin 8
    Pseudogene
    Keratin 5
    Citations (47)
    The distribution of the major keratin mRNAs expressed during terminal differentiation and fetal development of the rat intestinal epithelium has been examined by in situ hybridization. We have obtained and characterized a partial cDNA clone encoding human keratin 20 whose sequence spans from the coil la region through the 3′poly(A) tail. Sequence data and immunoblot analysis demonstrated that keratin 20 is the human homologue of the rat keratin 21, suggesting the existence of a single type I keratin specifically expressed by differentiated intestinal epithelial cells. Four cRNA probes, specific for keratins 8, 18, 19, and 20 respectively, were prepared and found to specifically hybridize with their respective mRNA species from total intestinal RNA preparations. Analysis of frozen tissue sections by in situ hybridization revealed that, in the adult intestine, keratin 18 and 19 mRNAs are restricted to the region of the crypts, keratin 8 mRNA is found along the entire crypt-villus axis, and keratin 20 mRNA is expressed only by the differentiated villus cells. This pattern is established late during fetal rat intestinal development: in the undifferentiated stratified epithelium present at 16 days gestation (16dg) mRNAs coding for keratins 8, 18, and 19 are expressed by all epithelial cells and keratin 20 mRNA is absent. Upon completion of villus formation at 20dg (2 days before birth) keratin 18 and 19 mRNAs become strictly confined to cells at the base of the nascent villi and we observed the appearance of keratin 20 mRNA which, like keratin 8 mRNA, is expressed by the entire epithelium. These results strongly suggest that transcriptional regulation of keratin genes in the intestinal epithelium occurs at the level of both immature and terminally differentiated epithelial cells, and is tightly regulated during both fetal development and crypt-to-villus differentiation of the intestinal epithelium.
    Keratin 7
    Keratin 6A
    Keratin 8
    Keratin 5
    Keratin expression in human tissues and neoplasms Keratin filaments constitute type I and type II intermediate filaments (IFs), with at least 20 subtypes named keratin 1–20. Since certain keratin subtypes are only expressed in some normal human tissues but not others, and vice versa , various tissues have been subclassified according to the pattern of keratin staining. Simple epithelia generally express the simple epithelial keratins 7, 18, 19, and 20, while complex epithelia express complex epithelial keratins 5/6, 10, 14, and 15. When an epithelium undergoes malignant transformation, its keratin profile usually remains constant. The constitution and expression patterns of keratin filaments in human epithelial neoplasms are complex and often distinctive. In this article, we first briefly review the molecular and cell biology of keratin filaments. We then focus on the expression patterns of keratin filaments in various human neoplasms.
    Keratin 6A
    Keratin 7
    Keratin 8
    Keratin 5
    Keratin 14
    Cell type
    Here, we report on the analysis of keratin 18 null mice. Unlike the ablation of K8, which together with K18 is expressed in embryonic and simple adult epithelia, K18 null mice are viable, fertile, and show a normal lifespan. In young K18 null mice, hepatocytes were completely devoid of keratin filaments. Nevertheless, typical desmosomes were formed and maintained. Old K18 null mice, however, developed a distinctive liver pathology with abnormal hepatocytes containing K8-positive aggregates. These stained positively for ubiquitin and MM120-1 and were identified as Mallory bodies, one hallmark of human alcoholic hepatitis. This is the first demonstration that the ablation of one keratin leads to the accumulation of its single partner. Another striking finding was the absence or drastic down regulation of K7 in several tissues despite its ongoing transcription. Moreover, K18 null mice revealed new insights in the filament-forming capacity of the tail-less K19 in vivo. Due to the unexpected secondary loss of K7, only K8/19 are expressed in the uterine epithelium of K18 null mice. Immunoelectron microscopy of this tissue demonstrated the presence of typical K8/19 IF, thus highlighting in vivo that K19 is a fully competent partner for K8.
    Keratin 8
    Keratin 7
    Keratin 5
    Knockout mouse
    Citations (206)