Keratin cytoskeletons in epithelial cells of internal organs

Abstract

An antiserum against human epidermal keratins was used to detect keratins in frozen sections of various rabbit and human tissues bv indirect immunofluorescence. Strong staining was observed in all stratified squamous epithelia (epidermis, cornea, conjunctiva, tongue, esophagus, vagina, and anus), in epidermal appendages (hair follicle. sebaceous gland, ductal and myoepithelial cells of sweat glands), as well as in Ilassall's corpuscles of the thymus, indicating that all contain abundant keratins. No staining by the antiserum was observed in fibroblasts, muscle of anv tvpe, cartilage, blood vessel, nerve tissue, iris or lens epithelium, or the glomerular or tubular cells of the kidnev. In contrast, the antiserum stained the cells of most epithelia of the intestinal tract, urinary tract (urethra, bladder, ureter, collecting ducts of kidney), female genital tract (cervix, cervical glands, uterus, and oviduct), and respiratory tract (trachea and bronchi). Epithelial cells of the fine ductal system in the pancreas and submaxillary gland also stained well. When primary cultures of epithelial cells derived from bladder, intestine, kidney, and trachea were grown on glass coverslips and stained with anti-keratin, fiber networks similar to those of cultured keratinocytes were observed. These results show that keratins constitute a cytoskeleton in epithelial cells of diverse morphology and embryological origin. The stability of keratin filaments probably confers the structural strength necessary for cells covering a free surface. Keratin staining can be used to obtain information about the origin of cell lines. The stratified squamous epithelium is the most common covering or lining surface of the animal body. It may be of ecto-(lernmal origin (the epidermis) or of endodermal origin (the esophageal epithelium). The dominant cell type of these epithelia (the keratinocvte) contains abundant 80-A filaments composed of keratin proteins. Cells of this type cultivated from different stratified sqltuamolus epithelia are rather similar (1), keratins accounting for about 30% of the cellular protein.Most other epithelia, such as those of the intestinal, respiratory, genital, and urinary tracts, seem quite different. Although the cells of these epithelia frequently contain 80-to 100-A filaments, they are not as abundant as those of the keratinocvte and mav not show their typical lateral aggregation. The cells of epithelia other than stratified squamous are often secretory and have morphology and specialization very different from those of the keratinocvtes.The keratins of human stratum corneum have been purified as a group and used to make a rabbit antiserum (2). This antisertim produces specific precipitin lines when tested against extracts of keratinocytes, and it stains by indirect immunofluorescence a network of fibers wvithin the cytoplasm of keratinocytes (3). Using this serum, wve show here that keratins are present not only in cells of all stratified squjamous epithelia (of hunman and rabbit) tumt also in many other e...

Identification of cytokeratin antigens in Novikoff ascites hepatoma.

“…Ofparticular relevance to this report are the keratins that are polypeptide components of the latter two groups. A number of reports have shown the specificity of the keratins not only to epidermis but to nonkeratizing epithelial cells as well (14,(16)(17)(18)(19)(20)(21)(22).The solubility properties ofthe keratins (23-26) are very similar to those we observed for the Novikoff hepatoma nuclear antigens during our purification attempts with these proteins. Moreover, the molecular weights ofthe denatured antigens are very similar to those reported for keratins or prekeratins from a number ofsources (14,15,(26)(27)(28)(29).…”

Cytokeratin 7 and Cytokeratin 20 Expression in Epithelial Neoplasms: A Survey of 435 Cases

“…However, the highly diverse expression patterns of CKs have been correlated with different pathways of epithelial differentiation, and thereby allow the accurate and sophisticated classification of epithelial cells into different subtypes (1,7,8). During cell transformation and tumor development, this cell type specificity of cytokeratins is largely conserved (4,9).…”

Keratins as the main component for the mechanical integrity of keratinocytes

“…Keratinocytes represent the major cell type of mammalian epidermis and are mainly responsible for barrier functionality (1,2). On the molecular level, mechanical cell properties mainly depend on cytoskeletal fibrous structures (3), namely actin filaments, microtubules, and intermediate filaments (IFs).…”