ABSTRACT
Recessive X-linked ichthyosis (RXLI) has its biochemical basis in a defect of the enzyme steroid sulfatase. Since several studies have reported a simultaneous deficiency of arylsulfatase C and steroid sulfatase it has been hypothesized that both enzymes are identical. In human hair follicles, however, hydrolytic activity for 4-methylumbelliferone sulfate, the substrate for arylsulfatase C, is found, while dehydroepiandrosterone sulfate is not hydrolyzed at all. These findings suggested the possible existence of two different enzymes. In the present paper structure-activity studies and molecular energy calculations are used for the demonstration that the remaining sulfatase activity in hair follicles of RXLI patients can be explained on the basis of the assumption that the enzyme has not lost its total function but has become less efficient.
Subject(s)
Hair/enzymology , Ichthyosis/enzymology , Sulfatases/metabolism , Adolescent , Adult , Dehydroepiandrosterone/analogs & derivatives , Dehydroepiandrosterone/metabolism , Dehydroepiandrosterone Sulfate , Equilenin/metabolism , Estrone/analogs & derivatives , Estrone/metabolism , Female , Genetic Linkage , Humans , Hymecromone/analogs & derivatives , Hymecromone/metabolism , Ichthyosis/genetics , Male , Middle Aged , Substrate Specificity , X ChromosomeABSTRACT
Calmodulin levels were measured by radioimmuno-assay in freshly isolated and cultured psoriatic human scalp hair follicle cells. The mean value +/- SEM for calmodulin was 1.97 +/- 0.15 ng calmodulin micrograms-1 protein for 16 control subjects whereas calmodulin levels were significantly increased in psoriatic hair follicles, 2.93 +/- 0.26 ng calmodulin micrograms-1 protein (uninvolved skin) for 18 patients and 3.09 +/- 0.21 ng calmodulin micrograms-1 protein for involved skin derived hair follicles for 17 of these patients. In vitro, 3-week-old cultures of psoriatic keratinocytes contained less DNA and more calmodulin per DNA than their normal counterparts. When 6 week-old cultures of psoriatic and control hair follicle keratinocytes were compared, this difference disappeared. These results are related to the state of differentiation of these cultures.
Subject(s)
Calmodulin/metabolism , Hair/metabolism , Psoriasis/metabolism , Culture Techniques , Epidermis/metabolism , HumansABSTRACT
Primary cultures of human and murine (strain C3Hz) bronchial epithelial cells were pretreated with benz(a)anthracene (BA) (10 microM). 16 h later the formation of phenolic as well as dihydrodiol metabolites of benzo(a)pyrene (BP) was measured. Whereas murine cultures showed enhanced metabolism towards both phenolic and dihydrodiol compounds, in the human cultures only phenolic BP-metabolites were increased. In view of their precursor role in the formation of biologically active diol-epoxides, formation of dihydrodiol-derivatives can be considered as a key factor in determining susceptibility to polycyclic aromatic hydrocarbon (PAH)-induced carcinogenesis. Therefore the observations of this study indicate that animal model systems for PAH carcinogenesis in man have to be selected on the basis of comparable metabolite patterns.
Subject(s)
Benz(a)Anthracenes/toxicity , Benzopyrenes/metabolism , Bronchi/metabolism , Animals , Benzo(a)pyrene , Cells, Cultured , Humans , Male , Mice , Mice, Inbred C3HABSTRACT
The formation of the 7, 8-a and 9, 10-dihydrodiol metabolites of benzo(a)pyrene, which are believed to play a role in the chemical induction of tumors, was investigated in cultures of human and murine origin. It was found that cultures of mouse (strain C3Hz) epidermal and skin fibroblastic cells showed inducible benzo(a)pyrene metabolism towards dihydrodiol metabolites, after pre-incubation with benz(a)anthracene. This was consistent with the increased in vivo formation of dihydrodiol metabolites of benzo(a)pyrene after injection with 3-methylcholanthrene. In contrast, in human cell cultures the metabolism of benzo(a)pyrene to the dihydrodiol metabolites was not enhanced after pre-exposure to benz(a)anthracene. This was the case in low-passage skin fibroblasts, primary epidermal skin cells, and primary keratinocytes from hair follicles. Moreover, other inducers of microsomal oxygenases, such as phenobarbital and 3-methylcholanthrene, were also unable to increase benzo(a)pyrene metabolism towards the dihydrodiol compounds. In view of these results, obtained using in vitro human and murine model systems, we may conclude that human and murine skin cell culture systems respond differently to pre-treatment with inducers of microsomal monooxygenases with respect to the metabolism of benzo(a)pyrene to reactive dihydrodiol metabolites. The possible implications for the human in vivo situation are discussed.
Subject(s)
Benzopyrenes/metabolism , Dihydroxydihydrobenzopyrenes , Animals , Aryl Hydrocarbon Hydroxylases/biosynthesis , Autoradiography , Cells, Cultured , Enzyme Induction/drug effects , Fibroblasts/metabolism , Humans , In Vitro Techniques , Methylcholanthrene , Mice , Mice, Inbred Strains , Skin/cytology , Skin/metabolismABSTRACT
Basal levels of benzo(a)pyrene metabolism were measured in hair follicles of seven monozygotic twins, eight dizygotic twins and ten pairs of unrelated individuals. Organic soluble metabolites were separated by thin-layer chromatography, visualised by autoradiography and quantified by scanning of the films. Activity was expressed as pmol 7,8- and 9,10-dihydrodiol metabolites of benzo(a)pyrene per micrograms DNA per hour. Intra-twin differences in benzo(a)pyrene metabolism for monozygotic twins were smaller than for dizygotic twins and intra-pair differences for dizygotic twins were smaller for pairs of unrelated individuals. The results clearly suggest that individual differences in benzo(a)pyrene metabolism in hair follicles are partly genetically determined. Thus, hair follicles may be used for investigations on the suggested relations between genetic predisposition to carcinogen-induced cancer and individual differences in carcinogen metabolism. The relevance of these findings to research into the induction of neoplasms by carcinogens in epithelial tissues is discussed.
Subject(s)
Benzopyrenes/metabolism , Carcinogens/metabolism , Hair/metabolism , Aryl Hydrocarbon Hydroxylases/metabolism , Autoradiography , Benzo(a)pyrene , Chromatography, Thin Layer , Disease Susceptibility , Female , Humans , Male , Pregnancy , TwinsABSTRACT
The enzyme aryl hydrocarbon hydroxylase is present in murine and human cultures of keratinocytes. While the activity of aryl hydrocarbon hydroxylase in murine cultures was found to be inducible after exposure to benz(a)anthracene, human keratinocytes originating from the hair follicle did not respond to this treatment. Hence, cultured human keratinocytes are not suitable for studying the molecular events that mediate the process of aryl hydrocarbon hydroxylase induction.
Subject(s)
Aryl Hydrocarbon Hydroxylases/biosynthesis , Benz(a)Anthracenes/pharmacology , Hair/enzymology , Skin/enzymology , Animals , Animals, Newborn , Autoradiography , Cells, Cultured , Enzyme Induction , Epithelium/enzymology , Hair/cytology , Humans , Mice , Species SpecificityABSTRACT
Human hair follicles may be useful for determining individual differences in the metabolism of polycyclic aromatic hydrocarbons in epithelial tissues. for quantitative measurements of carcinogen metabolism, determination of the amount of DNA in the hair follicles is necessary in order to correct for individual size variation. A simple method for DNa determination in hair follicles is described, based on the use of a hypotonic pronase solution to solubilise DNA which is then available for complex formation with mithramycin or 4,6-diamidino-2-phenylindole. 2HCI (DAPI). The mithramycin method permits the measurement of DNA in a small number of hair follicles, while the DAPI method is sensitive for as little as one single bulb.
