Skin Of Control Mice Research Articles

Selective decrease of type I collagen synthesis in Fraser mice skin

Quantification and biosynthesis of type I and type III collagens were determined in skin of control and Fraser mice (Cat Fraser mutation), which exhibit a genetically determined cataract. Skin organ cultures were labelled with [ 3H]proline. Pepsin-solubilized collagens were studied using three different approaches: (a) differential salt precipitation at neutral pH, followed by SDS-polyacrylamide gel electrophoresis; (b) differential salt precipitation at acid pH followed by SDS-polyacrylamide gel electrophoresis. (c) CNBr peptide analysis. These methods gave consistent and reproducible results, indicating a selective decrease of type I collagen in Fraser mouse skin as compared to control mouse skin. Metabolic labelling of skin organ cultures showed a decreased specific radioactivity of hydroxy[ 3H]proline in type I collagen of Fraser mouse skin. The concordant results of these experiments suggest a genetically determined alteration of interstitial collagen metabolism in the Fraser mutation apparently specifically concerning the expression of type I collagen gene(s).

Histamine metabolism in skin of MRL/l mice.

Of several murine autoimmune models, MRL/Mp-lpr/lpr (MRL/l) mice are the most attractive from a dermatopathological point of view, because their skin lesions resemble the erythematous lesions of systemic lupus erythematosus (SLE). In order to clarify the pathogenesis of lupus dermatoses, histamine and its metabolizing activities in the skin of MRL/l mice were investigated. The specific activities of histamine-N-methyltransferase (HMT) in the skin of MRL/l mice were significantly lower than those in the skin of control mice i.e., MRL/Mp-+/+ (MRL/n), C57BL/6J, and BALB/c mice. In the dorsal lesional skin of MRL/l mice, HMT activities were markedly lower than those in normal abdominal skin. In addition, age-related analysis of HMT levels in the dorsal skin of MRL/l mice revealed that HMT activities reached their maximum at the age of 2 or 3 months and then decreased at 4 or 5 months when skin manifestation appeared: however, HMT activities in the abdominal skin increased almost linearly with age. There were no significant differences in histamine content in these mice, and diamine-oxidase activities were not detected in any skin specimens. From these results, it is suggested that impaired histamine metabolism is a particular biochemical feature of the skin of MRL/l mice.

Mouse skin cells resistant to terminal differentiation associated with initiation of carcinogenesis.

In chemical carcinogenesis, initiation is defined as the exposure of a tissue, generally mouse skin, to a limited dose of carcinogen which by itself does not induce tumours1. Subsequent treatments, usually by tumour promoters, are required to allow expression of initiation. In the absence of further treatment, the initiated cells are not recognizable by any known biochemical or biological criteria and the tissue itself functions normally. Much research has centred on elucidating the mechanism of initiation1–3. It seems likely that initiation involves a genetic change in the target cell as its expression after tumour promotion is a permanent characteristic of the tissue, even if many cell generations have elapsed between initiation and promotion4. Studies on tissues from patients with familial polyposis coli suggest that the occurrence of initiated cells in these individuals is due to an autosomal dominant gene5. Few studies have actually attempted to define the biological nature of the initiating alteration itself. We report here that cells resistant to terminal differentiation can be readily isolated from skin of BALB/c mice exposed to an initiating dose of carcinogen in vivo but not from control mouse skin. Also, we found that one strain of mouse (SENCAR) might contain a preexisting population of cells resistant to differentiation, and possibly initiated for tumorigenesis.

Biosynthesis of skin collagens in normal and diabetic mice.

Synthesis of collagens in vitro was studied on minced mouse skins incubated with [3H]-proline in organ-culture conditions. A comparative study was carried out on genetically diabetic mice (KK strain) and control mice (Swiss strain). After incubation, neutral-salt-soluble and acid-soluble collagens were extracted. The insoluble dermis was digested by pepsin and type I and type III collagens separated by differential precipitation in neutral salt solutions. Type I and Type III collagens were characterized by ion-exchange and molecular-sieve chromatography, amino acid analysis and by the characterization of CNBr peptides. In diabetic-mouse skin, the relative proportion of type III collagen was significantly higher than in control-mouse skin. The incorporation of radioactively labelled proline into hydroxyproline of type III collagen was significantly faster in diabetic-mouse skin than in control-mouse skin. No significant modifications in the total collagen content of the skin or of their rates of synthesis were observed between the two strains. Alteration in the ratio of type III to type I collagen in the diabetic-mouse skin can be interpreted as a sign of alteration of the regulation of collagen biosynthesis and may be related to the structural alterations observed in the diabetic intercellular matrix.

Study on the hyaluronic acid-protein complex, the molecular size of hyaluronic acid and the exchangeability of chloride in skin of mice before and after oestrogen treatment.

Abstract: Hyaluronic acid (HA)‐protein complex was extracted with 0.2 M‐NaCl from homogenized skin of the back of mice. The complex was separated from unrelated proteins by ethanol precipitation followed by three times chromatography on CM‐Sephadex columns. The composition of the complex isolated from mice treated with oestradiol differed significantly from the complex of the control mice, the ratio HA/protein was 3.5 times higher in the former than in the latter. The molecular sizes of the HA from the two samples were compared by means of gel filtration on Sepharose 2B column. Apart from a high molecular fraction containing 4 % of the HA from mice treated with oestradiol no difference was found between the elution patterns. The exchangeability of the chloride in the skin of control mice and mice treated with oestradiol was studied by means of the isotope dilution method. No significant difference was found between the two groups of mice.