We formulate a mathematical model to study the in vivo keratin organization in terms of repartition of the keratin material between three different structural states: soluble proteins, filament precursors and filamentous state. The model describes a cycle of assembly and disassembly of keratin material. A generic nucleation function and structural stability of filament precursors are assumed. I...

In 1978 Sun and Green carried out a densitometry-based analysis of polyacrylamide gelelectrophoresed samples and reported that keratin proteins account for 25~35% of total cellular proteins in human epidermal keratinocytes serially passaged in primary culture. This represents an astounding figure with very significant implications for the structural support role of keratin intermediate filament...

Most type I and II keratin genes are spatially and temporally regulated in a pairwise manner in epithelial tissues, where they represent the major structural proteins. Epithelia can be partitioned into simple (single-layered) and complex (multilayered) types. We compared the structural and mechanical properties of natural keratin polymers occurring in complex (K5-K14) and simple (K8-K18) epithe...

Rat keratin K5 and vimentin complementary DNAs have been isolated, identified, and used to study keratin and vimentin expression as markers for cell differentiation. Isologous rat neoplastic epithelial cell lines used were based on a clonal benign epithelial line (A5P/B10) and a clonal anaplastic malignant derivative line (T952/F7). Stable cytoplasmic mRNA was detected for keratin but not vimen...

We report two cases of eccrine porocarcinoma (EPC), one of intrepidermal EPC (IEEPC) and one of intradermal invasive EPC (IDEPC) in an immunohistochemical study of cytokeratins (CK) using nine different anti-keratin antibodies against CK1, 7, 8, 10, 14, 16, 17, 18 and 19. IEEPC expressed terminal differentiated CK1 and CK10. In contrast, IDEPC expressed simple-epithelial keratins such as CK7, 8...

The stratified squamous epithelium is a model system in which to define molecular mechanisms underlying the switch from proliferation to differentiation. This can be achieved through the functional dissection of keratin gene promoters. Having previously established the importance of keratin 4 in maintaining the differentiated phenotype in corneal epithelial cells, we investigated the role of Sp...

Keratin from the hoof is a less explored source for making valuable products. In this paper we present the extraction of pure keratin from bovine hooves and characterized them to better address the possible exploitation of this bio-resource as an alternative material for tissue engineering applications. The keratin protein from the pulverized hooves was extracted by reduction, which was observe...

Keratin polypeptides 8 and 18 (K8/18) are the major intermediate filament proteins of simple-type epithelia. K18 Ser-33 phosphorylation regulates its binding to 14-3-3 proteins during mitosis. We studied the significance of keratin binding to 14-3-3 in transgenic mice that overexpress wild-type or Ser-33-->Ala (S33A) K18. In S33A but not wild-type K18-overexpressing mice, pancreatic acinar cell...

Epiplakin is a large (>725 kDa) cytoskeletal protein exclusively expressed in epithelial tissues. It has a unique structure, consisting entirely of plakin repeat domains (PRDs), one of the hallmarks of spectraplakin protein family members. Previous studies, including the phenotypic analyses of knockout mice, failed to reveal the biological function of epiplakin. Using in vitro binding assays, w...

Keratin 8 (K8) serine 73 occurs within a relatively conserved type II keratin motif ((68)NQSLLSPL) and becomes phosphorylated in cultured cells and organs during mitosis, cell stress, and apoptosis. Here we show that Ser-73 is exclusively phosphorylated in vitro by p38 mitogen-activated protein kinase. In cells, Ser-73 phosphorylation occurs in association with p38 kinase activation and is inhi...