involucrin and Keratosis--Seborrheic

The F1F0-ATP synthase, an enzyme complex, is mainly located on the mitochondrial inner membrane or sometimes cytomembrane to generate or hydrolyze ATP, play a role in cell proliferation. This study focused on the role of F1F0-ATP synthase in keratinocyte differentiation, and its relationship with intracellular and extracellular ATP (InATP and ExATP). The F1F0-ATP synthase β subunit (ATP5B) expression in various skin tissues and confluence-dependent HaCaT differentiation models was detected. ATP5B expression increased with keratinocyte and HaCaT cell differentiation in normal skin, some epidermis hyper-proliferative diseases, squamous cell carcinoma, and the HaCaT cell differentiation model. The impact of InATP and ExATP content on HaCaT differentiation was reflected by the expression of the differentiation marker involucrin. Inhibition of F1F0-ATP synthase blocked HaCaT cell differentiation, which was associated with a decrease of InATP content, but not with changes of ExATP. Our results revealed that F1F0-ATP synthase expression is associated with the process of keratinocyte differentiation which may possibly be related to InATP synthesis.

Topics: Adenosine Triphosphate; Carcinoma, Squamous Cell; Cell Differentiation; Cell Line, Transformed; Dermatitis; Gene Expression Regulation; Humans; Keratinocytes; Keratoacanthoma; Keratosis, Seborrheic; Mitochondria; Mitochondrial Membranes; Mitochondrial Proton-Translocating ATPases; Protein Precursors; Prurigo; Psoriasis; Skin; Skin Neoplasms; Warts

We investigated protein expression and in situ activity of transglutaminases (TGs) in normal skin and various epidermal neoplasms. In normal skin, TG1 protein expression and TG activity were found at keratinocyte cell membranes in upper epidermis and granular layer, respectively. In seborrhoeic keratosis, TG1 protein was expressed evenly throughout tumors, while TG activity increased in gradient fashion from lower tumor area to cornified layer. In squamous cell carcinoma, TG1 protein was expressed at inner side of cell membranes, whereas TG activity was found in cytoplasm predominantly at horn pearls. In basal cell carcinoma, weak TG activity was found in cytoplasm of all tumor cells without the presence of TG1 protein. Immunoblotting and in situ activity assays using specific substrate peptides confirmed that TG2, but not TG1, contributed to the TG activity. These results suggested that different expression and activation of TGs may contribute to characteristics of the skin tumors.

Topics: Carcinoma, Basal Cell; Carcinoma, Squamous Cell; Cell Differentiation; Cell Line, Tumor; Gene Expression Regulation; Gene Expression Regulation, Neoplastic; Humans; Keratinocytes; Keratosis, Seborrheic; Protein Precursors; Skin; Skin Neoplasms; Transglutaminases

The mode of differentiation of seborrhoeic keratoses was investigated by immunohistochemical staining using cytokeratin (CK) polypeptide-specific monoclonal antibodies and an antibody specific for the particulate form of epidermal transglutaminase (ETgase), and by applying an anti-human involucrin serum. The role played by (E)Tgase was further evaluated using an activity assay based on the covalent attachment of monodansylcadaverine. Samples of uninvolved epidermis served as reference tissue. CK reactivities suggested that seborrhoeic keratoses is a hyperproliferative disease with an epidermal CK composition. CK5 and CK14 were prominent markers of basal and basaloid keratinocytes, whereas a decrease in staining occurred in advanced maturation stages and areas of terminal keratinization. In contrast, CK1 and CK10 were prominent markers of suprabasaloid differentiation stages and produced complementary stainings to those of CK5 and 14. Generally, CK10 staining was more impressive than CK1 staining and seemed to start before CK1 staining. In contrast to CK10 staining, cornified areas lost CK1 reactivity. These staining patterns were similar to those observed in uninvolved reference tissues. The epidermal CK subset was further supplemented with the 'hyperproliferative' CK6 and 16 which occur sequentially. Positive staining for CK6 was noted from basal and proximal basaloid cells onwards, whereas distal basaloid cells additionally showed CK16 staining. The presence of other non-epidermal CK polypeptides could not be shown. The competence for other differentiation markers belonging to the group of (E)Tgase and cornifying cell membranes also evolved with a typical epidermal pattern. (E)Tgase activity was restricted to advanced and terminal stages of keratinization and was dual in nature, i.e. a diffuse cytoplasmic staining occurred together with a prominent staining of cornifying cell membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Humans; Immunohistochemistry; Keratins; Keratosis, Seborrheic; Protein Precursors; Transglutaminases; Vimentin