Increased synergistic effect of EGF and IGF-I on DNA synthesis of cultured psoriatic keratinocytes.

Background: DNA synthesis is significantly more stimulated in response to insulin-like growth factor I (IGF-I) in growth-arrested cultures of psoriatic than of nonpsoriatic keratinocytes. Epidermal growth factor (EGF), by itself only a weak stimulator, was recently found to cause a strong synergetic effect when added together with IGF-I to newborn human keratinocytes.

Objective: (1) To measure this effect in cultured adult psoriatic and nonpsoriatic keratinocytes, and (2) to examine whether the difference in DNA synthesis after IGF-I addition could be due to differences in the binding of this growth factor.

Studies on stimulation of DNA synthesis with epidermal growth factor and insulin-like growth factor-I in cultured human keratinocytes.

Epidermal growth factor (EGF) and insulin are the most widely used growth factors (GFs) in human keratinocyte cultures. Insulin is supposed to exert its growth-promoting activity in this system through the insulin-like growth factor-I (IGF-I) receptor. In order to obtain more information about the contribution of EGF and IGF-I to the proliferation of keratinocytes, the effect of each factor on DNA synthesis was studied with 3H thymidine incorporation in an otherwise GF-free system.

Chromosomal damages by ethanol and acetaldehyde in Saccharomyces cerevisiae as studied by pulsed field gel electrophoresis.

We report on the effect of ethanol and acetaldehyde on yeast chromosomal DNA and on isolated DNA. Ethanol induced DNA single-strand breaks in repair deficient but not in repair proficient Saccharomyces cerevisiae. Acetaldehyde has a deleterious effect on chromosomal DNA in cells as well as on isolated DNA.

Effect of insulin-like growth factor-I/somatomedin C on thymidine incorporation in cultured psoriatic keratinocytes after growth arrest in growth factor-free medium.

Near confluent cultures of human keratinocytes will arrest in GO/G1 of the cell cycle when they are placed into growth factor (GF)-free medium with a Ca++ concentration below 0.1 mM for 4 days. Addition of certain growth factors will stimulate the cell to re-enter the growth cycle and move into the S-phase after 7-12 h.

Interleukin-1 does not stimulate DNA synthesis of cultured human keratinocytes growth-arrested in growth-factor-depleted medium.

Interleukin-1, a multifunctional cytokine, plays a central role in inflammatory processes. Several reports have appeared demonstrating that IL-1 stimulates growth of keratinocytes under certain experimental conditions, and we have shown previously that it can act as a strong stimulator of DNA synthesis in murine keratinocytes that have been growth-arrested by removal of growth factors (GF) from the medium for several days. Using the same assay system, we report here that, in contrast to cultured mouse keratinocytes, growth-arrested adult and newborn human keratinocytes do not respond to IL-1 with an increase in DNA synthesis.

Basic fibroblast growth factor and insulin-like growth factor I are strong mitogens for cultured mouse keratinocytes.

Basic fibroblast growth factor (bFGF), but not acidic fibroblast growth factor (aFGF), was found to be mitogenic for cultured mouse keratinocytes. A six-to-nine fold increase in 3H-thymidine (3H-dT) incorporation into the acid insoluble pool and a similar increase of the labeling index can be measured when bFGF, at a concentration between 1 and 10 ng/ml, is added to keratinocytes arrested in serum-free and growth factor-free medium with a Ca++-concentration below 0.1 mM.

Tyrocidine-induced modulation of the DNA conformation in Bacillus brevis.

Using the [3H]trimethylpsoralen photobinding method [Sinden, R.R., Carlson, J.

The GTP pool in Bacillus brevis and its significance for sporulation.

The GTP pool of Bacillus brevis as well as that of other nucleotides is highly sensitive to all kinds of environmental changes like the cell transfer procedures or nutrient depletion of the cells. In growing cultures, as well as in cells transferred from rich to nitrogen-deficient medium, the nucleotide pool decreases significantly. This decrease is followed by the onset of sporulation only when cells are allowed to produce the peptide antibiotic tyrocidine or if tyrocidine is added to the culture.

A major factor contributing to epidermal proliferation in inflammatory skin diseases appears to be interleukin 1 or a related protein.

Human peripheral blood leukocytes can stimulate G1(G0)-arrested mouse skin keratinocytes to enter the cell cycle again and synthesize DNA at the maximum rate 15-20 hr later. This growth-promoting activity is released by the monocyte fraction and is shown to have characteristics that have been reported for interleukin 1 (IL-1). Pure IL-1 is active in stimulating keratinocyte cultures as was shown with recombinant human IL-1.

DNA-supercoiling is affected in vitro by the peptide antibiotics tyrocidine and gramicidin.

Tyrocidine, a peptide antibiotic produced by Bacillus brevis (ATCC 8185), relaxes superhelical DNA in a biphasic manner and induces 'packaging' of the DNA at higher concentrations. This was concluded from studies using the sensitive 4,5',8-trimethylpsoralen photobinding technique [Sinden, R. R.

BSC-1 growth inhibitor/type beta transforming growth factor is a strong inhibitor of thymocyte proliferation.

Growth inhibitor/type beta transforming growth factor purified from BSC-1 cells and human platelets is shown to strongly inhibit the proliferation of Con A-stimulated mouse thymocytes. The inhibition can be achieved with growth inhibitor/type beta transforming growth factor concentrations approximately equal to 1/10th those necessary to inhibit keratinocyte cultures. The inhibitory effect in thymocyte cultures can be reversed by the addition of interleukin 2.

Peptide antibiotics and sporulation: induction of sporulation in asporogenous and peptide-negative mutants of Bacillus brevis.

Mutants of Bacillus brevis ATCC 8185 were isolated which were unable to produce detectable amounts of either tyrocidine or linear gramicidin, or both peptide antibiotics. Tyrocidine-negative mutants (BM5, BM21, BM44) sporulated normally. Gramicidin-negative mutants (BM2, BM24) were oligosporogenous, and mutants unable to produce both peptides (S18, S19) were asporogenous.

Induction of sporulation in Bacillus brevis. 2. Dependence on the presence of the peptide antibiotics tyrocidine and linear gramicidin.

This paper presents evidence that the two peptide antibiotics tyrocidine and linear gramicidin, produced by Bacillus brevis ATCC 8185, are required for the induction of sporulation in the producer organism. When tyrocidine synthesis was specifically blocked with 2-amino-3-hydroxy-3-phenylpropanoic acid [Mach, B., Reich, E.

Induction of sporulation in Bacillus brevis. 1. Biochemical events and modulation of RNA synthesis during induction by tyrocidine.

Under conditions of severe nitrogen starvation, brought about by nutritional shift-down, Bacillus brevis ATCC 8185 was unable to sporulate unless supplemented with the peptide antibiotic tyrocidine. The induction of sporulation was highly specific for tyrocidine and required only very low concentrations of the peptide (5 microM). Tyrocidine-induced sporulation was accompanied by the typical sporulation-specific events (e.

Stimulation of DNA synthesis in cultured mouse epidermal cells by human peripheral leukocytes.

Primary epidermal cells derived from the skin of newborn mice can be arrested in G1(G0) of the cell cycle when kept in serum-free medium with 0.06 mM Ca++ for 4 days. These cells can be restimulated to grow by the addition of Chelex 100-treated inactivated fetal calf serum, as shown by liquid scintillation counting and autoradiography after [3H]-thymidine incorporation and by counting mitotic figures.

Functions of the peptide antibiotics tyrocidine and gramicidin. Induction of conformational and structural changes of superhelical DNA.

The peptide antibiotic tyrocidine which is produced by Bacillus brevis and is probably involved in sporogenesis, unwinds superhelical plasmids in vitro at low peptide: DNA ratios, as found by gel electrophoresis. At higher peptide concentrations, the DNA is packed tightly leading to apparent nuclease stability of the complex and inhibition of RNA synthesis. The addition of the linear gramicidin, another peptide antibiotic synthesized by the same bacterial strain, partially restores transcription by breaking down the tightly packed DNA X peptide complex.

Harman and norharman: induction of sister-chromatid exchanges in human peripheral lymphocytes in vitro and interaction with isolated DNA.

Harman, but not norharman, induced sister-chromatid exchanges in human peripheral lymphocytes in vitro. Transcription of isolated DNA in vitro was inhibited by both compounds, harman being more effective than norharman. A filter-binding assay with isolated DNA showed that harman binds more effectively to the DNA than norharman.

Increased phosphatidylinositol synthesis in rat embryo fibroblasts after growth stimulation and its inhibition by delta-hexachlorocyclohexane.

When resting rat embryo fibroblasts are stimulated to grow, a substantial increase in phosphatidylinositol synthesis can be observed. This increase cannot be explained by increased glucose uptake or glycolysis. delta-Hexachlorocyclohexane having the same configuration as myo-inositol, inhibits phosphatidyl inositol synthesis as well as DNA synthesis and mitosis, but has no effect on phosphatidyl choline synthesis.

Stimulation of DNA synthesis any myo-inositol incorporation in mammalian cells.

Phosphatidylinositol (PI) synthesis and its role in controlling the cell cycle has been investigated using fibroblasts and liver cells in culture. PI synthesis as measured by incorporation of [3H]-myo-inositol into trichloroacetic acid precipitable material during 0--60 min after serum or growth factor stimulation of serum-starved cells is increased in primary fetal rat liver cells, rat embryo fibroblasts, and 3T3 mouse cells. In contrast, growth stimulation of 3T3 cells and hepatocytes rendered quiescent in G1 by amino acid starvation is not accompanied by increased incorporation of [3H[-myo-inositol into trichloroacetic acid precipitable material.

Mutagenic, cancerogenic and teratogenic effects of alcohol.

Alcohol is mutagenic, cancerogenic and teratogenic in man. Ethanol is mutagenic via its first metabolite, acetaldehyde. This is substantiated by the findings that acetaldehyde induces chromosomal aberrations, sister-chromatid exchanges and cross-links between DNA strands.

Cell cycle control by Ca++-ions in mouse 3T3 cells and in transformed 3T3 cells.

Total cellular calcium levels do not change when 3T3-4a cells stop proliferating due to serum depletion, or when serum-arrested quiescent cells are incubated for up to 44 hours in calcium-deficient medium (approximately 10 micrometer Ca++). Upon stimulation with dialyzed serum cells enter S and progress through at least one cycle even at extremely low calcium levels in the culture medium (greater than or equal to 10 micrometer). Cells divide until a final cell density is attained which is proportional to the calcium concentration in the medium and cells reversibly arrest in G1.

The DNA . tyrocidine complex and its dissociation in the presence of gramicidin D.

The peptide antibiotic tyrocidine affects transcription in vitro by interfering with the initiation process. The complex formed between tyrocidine and native DNA is stable against nucleolytic enzymes. It is sensitive to variations in the salt concentration.