Cell interactions in skin

Hunter, Graeme Kenneth (1979) Cell interactions in skin. PhD thesis, University of Glasgow.

Abstract

1. The literature concerning the growth and differentiation of skin cells is reviewed. The interaction between the dermis and epidermis of postembryonic skin is compared with other forms of mesodermal-epithelial interaction, and the possible involvement of gap junction-mediated transfer of molecules between the two tissue layers is discussed. 2. Cultures of epidermal keratinocytes and dermal fibroblasts were established from newborn mouse skin and adult guinea pig ear skin. The ability of these cells to form gap junctions with one another in vitro was examined by auto- radiographic analysis of 3H-uridine nucleotide transfer between prelabelled donor cells and unlabelled recipient cells. 3. A novel statistical approach was used to analyse the transfer of radiolabelled molecules between cells in culture. Comparison of the autoradiographic grain counts of recipient cells in contact with prelabelled donor cells and recipient cells not in contact with donor cells was used to generate a probability value which was used as a measure of cell-cell communication. 4. This method was used to demonstrate gap junction formation between epidermal keratinocytes and dermal fibroblasts in culture. 5. Junction formation between skin cells is in contradiction to published proposals of epithelial-fibroblastic specificity To determine whether this is an unusual situation, two other mouse primary cell types, epidermal melanocytes and renal epithelial cells, and cells of several established cell lines, were examined for gap junction formation in vitro. It was shown that epidermal keratinocytes, dermal fibroblasts renal epithelial cells and epidermal melanocytes communicate non-specifically with cells of the fibroblast line C13 and the epithelial cell line BRL. However, cells of the canine kidney epithelial line MDCK form gap junctions with one another but do not communicate with cells of the junction-competent C13 and BRL lines. From these results it was proposed that specificity in cell communication may be a more general property of established cell lines. 6. The epidermal structural protein prekeratin was used as a biochemical marker for epidermal cell differentiation in culture. Prekeratin from newborn mouse skin was purified by citrate buffer extraction, and shown to consist of polypeptide chains of 61,000MW and 69,000MW in a 2:1 stoichiometry. 7. A further method for the study of keratinocyte differentiation in vitro was developed, based on the relative uptake of the amino acids histidine and leucine. Using these techniques it was demonstrated that epidermal keratinocytes undergo only limited differentiation in dispersed cell culture. 8. The dermal-epidermal interaction was also studied using a transfilter organ culture system. Direct contact between dermis and epidermis was shown to result in stimulation of epidermal protein synthesis. This stimulation does not occur when the two tissues are separated by porous filters with a mean particle retention size of 0. 8um. However, no de novo prekeratin synthesis was detected by labelling of skin organ cultures with 35S-methionine and 3H-leucine. 9. The implications of these observations for the normal growth and differentiation of skin in vivo are discussed.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Biochemistry, Cellular biology
• Date of Award: 1979
• Depositing User: Enlighten Team
• Unique ID: glathesis:1979-76513
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 19 Nov 2019 14:14
• Last Modified: 19 Nov 2019 14:14
• URI: https://theses.gla.ac.uk/id/eprint/76513