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Biomedical subjects

J A Fairley

Publications and source records attributed to J A Fairley.

12 recordsLinked to original sources
PubMed1991

Characterization of keratocalmin, a calmodulin-binding protein from human epidermis.

Using affinity-purified calmodulin-binding proteins from human epidermis we have developed a monoclonal IgM antibody, ROC 129.1, to a human desmosomal calcmodulin-binding protein. This antibody reacts with a submembranous 250-kD protein from human keratinocytes and stains human epidermis in a "cell-surface pattern". Permeability studies indicated that the epitope with which this monoclonal reacts is on the inner surface of the cell membrane. Immunoelectronmicroscopy localized the antigen to the desmosome. The epitope is restricted to stratified squamous epithelia and arises between 8-12 wk of fetal development. This desmosomal calmodulin-binding protein, which we have termed keratocalmin, may be involved in the calcium-regulated assembly of desmosomes.

Animals↗
PubMed1991

Calcium metabolism and the pathogenesis of dermatologic disease.

Calcium has a major role in regulating epidermal functions, including cell proliferation, terminal differentiation, and cell-to-cell adhesion. Aberrations in calcium regulation have been noted in psoriasis when levels of the calcium binding protein calmodulin are elevated, and the normal calcium gradient within the epidermis is altered. Calcium may also be important in neoplasia because similar elevations in calmodulin have been noted in transformed cells. The function of calcium in mediating cell-cell adhesion may be important in understanding the acantholysis observed in pemphigus. The pemphigus foliaceus antigen appears to contain a calcium-sensitive epitope, and in pemphigus vulgaris, alteration in the function of calcium-sensitive cadherins may play a role in the production of acantholysis. Further understanding of the function of calcium in these processes may, in the future, allow us to alter calcium metabolism as a therapeutic intervention.

Animals↗
PubMed1990

Intracellular targets of cyclosporine.

Since cyclosporine was first reported to improve psoriasis, investigators have been trying to determine its mechanism of action. In addition to the well-documented effects on cytokine production by T lymphocytes, a direct effect on keratinocytes has been proposed. Cyclophilin and calmodulin, two proteins that are present in both lymphocytes and keratinocytes, have been considered as possible intracellular targets for cyclosporine. Cyclophilin binds cyclosporine with high affinity and the ability to bind cyclophilin correlates with the immunosuppressive effects of cyclosporine analogs. Cyclophilin is identical to peptidyl-prolyl cis-trans isomerase, an enzyme that catalyzes refolding of proteins. The process of protein folding may be important in DNA-protein and protein-protein interactions. Calmodulin is an intracellular calcium-binding protein that is important in the regulation of cell proliferation. Cyclosporine binds to calmodulin with low affinity, and such binding of cyclosporine isomers does not reflect their immunosuppressive activity. The physiologic importance of calmodulin-to-cyclosporine binding is controversial.

Amino Acid Isomerases↗
PubMed1990

Effect of ciclosporin A on epidermal keratinocytes in vitro: lack of a direct effect on calmodulin.

Calmodulin, a major calcium-binding protein, is important in the regulation of cell proliferation. In human keratinocytes we found that culture confluence was accompanied by a decrease in calmodulin content. Ciclosporin A, 1-10 micrograms/ml, was found to inhibit the proliferation of the cells but did not affect their calmodulin content as measured by bioassay or radioimmunoassay.

Calmodulin↗
PubMed1986

Monoclonal antibody to a 35 kD epidermal protein induces cell detachment.

A murine monoclonal antibody (ECS-1) was prepared from BALB/c mice immunized with trypsinized cultured human foreskin keratinocytes. The antibody showed a pattern suggestive of intercellular staining on the nucleated layers of normal human epidermis, adult palm, mouse lip epidermis, and cultured human keratinocytes. ECS-1 stained human fetal skin by 9 weeks estimated gestational age. ECS-1 reacted with a 35 kD protein extracted from neonatal foreskin epidermis and cultured human keratinocytes. The protein required Nonidet P-40 or sodium dodecyl sulfate and mercaptoethanol for solubilization. ECS-1 induced epidermal cell detachment which was enhanced by complement. ECS-1 shares characteristics with human pemphigus antibodies.

Animals↗
PubMed1986

Increased prostaglandin synthesis by low calcium-regulated keratinocytes.

The effect of calcium concentration on the in vitro prostaglandin production by murine keratinocytes was studied using radioimmunoassay. Keratinocytes grown in low-calcium medium (0.02 mM) maintained intracellular calcium levels adequate for arachidonic acid metabolism and actually showed increased prostaglandin production. Baseline, unstimulated PGE2 production was 4.5 times higher in cells growing in low- compared to normal-calcium (1.2 mM) medium (p = 0.001). PGF2 alpha production was increased 2.5 times in the low-calcium cells (p = 0.002). The calcium ionophore A23187 and 12-O-tetradecanoyl-phorbol-13-acetate (TPA) exhibited differing calcium requirements for activation of the arachidonic acid pathway. A23187 ionophore stimulated prostaglandin synthesis only in cells growing in normal-calcium medium while TPA stimulated prostaglandin production by both low- and normal-calcium cells. Paradoxically, short-term exposure of low calcium-grown cells to normal-calcium medium abolished the TPA effect. These results suggested that calcium can control arachidonic acid metabolism at a number of regulatory points.

Arachidonic Acid↗
PubMed1985

Actin in human corneal epithelium.

Actin, a major protein involved in muscle cell contraction, is also associated with cell motility, cell-substrate adhesion, and cell-shape changes in non-muscle cells. By electrophoresis and scanning densitometry, actin was found to constitute about 4% to 6% of the total cellular protein in the human corneal epithelium. The fluorescent probe, NBD-phallacidin, which specifically binds to filamentous actin (F-actin), was used to demonstrate the distribution of this protein in cultured corneal epithelial cells obtained from human eyebank eyes. Actin was present in the cytoplasm in two, often coexisting, patterns: (1) within numerous parallel and convergent linear bundles known as stress fibers, and (2) diffusely in the cytoplasm, with a cortical region of increased density in the peripheral cytoplasm adjacent to the plasmalemma. Actin has been implicated in the generation of cellular movement forces during the migration phase of corneal epithelial healing. Stress fibers, however, may not be absolutely necessary for the generation of the actual locomotive forces, but may function instead in anchoring the cell to the substrate and in elaborating cell-shape changes during cell spreading.

Actins↗
PubMed1985

Increased calmodulin levels in psoriasis and low Ca++ regulated mouse epidermal keratinocyte cultures.

Calcium has been shown to regulate the proliferation of epidermal keratinocytes in vitro. We became interested in the role of the calcium binding protein, calmodulin, in hyperproliferative, low calcium regulated keratinocytes in vitro and in the in vivo hyperproliferative state, psoriasis. Calmodulin levels were measured by radioimmune assay in neonatal mouse keratinocytes grown in 0.02 mM calcium (hyperproliferative) and 1.2 mM calcium (normal) media, and in cells that had been grown in low calcium medium and then switched to normal calcium. On a whole culture basis the normal cells had more calmodulin than the low calcium cells. However, when low calcium monolayers were compared to the normal basal monolayer, the low calcium hyperproliferative cells had more calmodulin. Cells that were switched from 0.02 mM calcium to 1.2 mM calcium showed increasing calmodulin levels over time. Psoriatic plaques contained 2-3 times more calmodulin than the skin of normal controls when examined on a per micrograms of DNA, per micrograms of protein, and per gram of wet weight basis. Adjacent uninvolved psoriatic skin also had significantly elevated calmodulin levels in all data bases except per microgram of protein/cm2. These data suggest that increased calmodulin levels are associated with epidermal hyperproliferation and/or with the state of differentiation.

Animals↗