Induction of cytochrome P‐450 b, e‐type isozymes by polychlorionated biphenyls in rat liver

Scholte, Bob J.; Velde, Bert te; Groot, G.S.P.; Vries, J. de

doi:10.1111/j.1432-1033.1985.tb09069.x

Cited by 9 publications

(7 citation statements)

References 46 publications

(13 reference statements)

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“…The polysomes were extracted with phenol-w-cresol-chloroform (1:0.14:1 by volume), and RNA was precipitated with ethanol. Blot hybridization to [a-32P]UTP-labeled RNA probes complementary to P-450b,e mRNA (PB-1) was performed as described elsewhere (Scholte et al, 1985). Blot hybridization to 32P-end-labeled oligonucleotide probe for P-450j was performed at 60 °C with 2 X 106 dpm/mL oligomer as described in Davis et al (1986).…”

Section: Methodsmentioning

confidence: 99%

Ethanol-, fasting-, and aceton-inducible cytochromes P-450 in rat liver: regulation and characteristics of enzymes belonging to the IIB and IIE gene subfamilies

Johansson¹,

Ekström²,

Scholte³

et al. 1988

Biochemistry

301

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Two major forms of hepatic microsomal cytochrome P-450 were purified from starved and acetone-treated rats. On the basis of amino acid sequence analysis, they were identified as P-450j and P-450b. Ethanol or acetone treatment of rats caused a 9-fold increase in the amount of P-450j in liver microsomes accompanied by similar increases in the rate of NADPH-dependent metabolism of carbon tetrachloride, acetone, and benzene. Immunological experiments indicated that P-450j constitutes the major catalyst of the microsomal metabolism of the latter agents and contributes by about 50% to microsomal P-450-dependent ethanol oxidation under the conditions used. The P-450j-dependent catalytic activities had a high rate of turnover. In contrast, this was not the case for the immunodetectable P-450j, indicating the occurrence of inactive forms of this protein in microsomes. Starvation or ethanol or acetone treatment caused 10-30-fold increases in the amount of both mRNA and apoprotein of P-450b,e compared to control. Run-on experiments and the concomitant increases of the P-450b,e gene products at the mRNA and protein levels indicated the appearance of mainly a transcriptional activation by acetone, ethanol, or starvation. Fasting exerted, in addition, a pronounced synergistic effect on acetone-dependent induction of P-450b,e mRNA (3-fold), apo-P-450b,e (4.3-fold), P-450j mRNA (2-fold), and apo-P-450j (2-fold). No increase of mRNA coding for P-450j, compared to control, was seen after acetone or ethanol treatment alone. The results indicate that effects of ethanol, acetone, and/or starvation on drug and xenobiotic metabolism are caused by the induction of P-450 forms belonging to at least two gene subfamilies.

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Section: Methodsmentioning

confidence: 99%

Ethanol-, fasting-, and aceton-inducible cytochromes P-450 in rat liver: regulation and characteristics of enzymes belonging to the IIB and IIE gene subfamilies

Johansson¹,

Ekström²,

Scholte³

et al. 1988

Biochemistry

301

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“…liver (Scholte et al, 1985) flanked by the leader his4-519, canl; Erhart and Hollenberg, 1981) was of the yeast ~2 5 ribosomal protein gene (Leer, transformed using various procedures described by 1985). The gene was under the Beg@ (1978), Carter et al (1988) and Klebe et al control of the yeast GAL10 promoter (Guarente (1983).…”

Section: Strains Transformants and Culture Conditionsmentioning

confidence: 99%

“…However, as demonstrated in Figure 4, the mitotic stability of pMIRY2 vectors carrying such a gene is decreased significantly. Yeast cells transformed with either pMIRY4-GC25, which contains the rat liver cytochrome P450-e cDNA (Scholte et al, 1985), or pMIRY4-GT25, carrying the cDNA for preprothaumatin from T. danielli (Edens et al, 1984), both under control of the GAL10 promoter, lose some 80% of their vector copies over a period of 70 generations of growth in non-selective medium containing galactose as the sole carbon source.…”

Section: Inzuence Of Gene Expression On the Mitotic Stability Of Pmirmentioning

confidence: 99%

Factors affecting the mitotic stability of high-copy-number integration into the ribosomal DNA of Saccharomyces cerevisiae

Lopes

Wijs

Steenhauer

et al. 1996

Yeast

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Yeast vectors suitable for high‐level expression of heterologous proteins should combine a high copy number with high mitotic stability. The pMIRY integrative vector system, based upon targeted integration into the yeast rDNA locus, developed in our laboratory satisfies these criteria. However, insertion of a (foreign) gene drastically reduced its mitotic stability of the resulting vector in comparison to its parent. In this paper we have investigated a number of possible reasons for this reduction in stability. The results demonstrate that plasmid size is an important, but not the only, determinant of mitotic stability. Stable maintenance is only observed when the complete plasmid has a size no larger than that of the rDNA unit (9·1 kb). In addition stability depends upon the nature of the rDNA fragment present in the plasmid, required for targeting its integration. On the other hand, it turned out to be irrelevant for mitotic stability whether the heterologous gene was expressed or not. These findings will be important in the design of a pMIRY vector suitable for industrial production of heterologous proteins.

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“…RNA and DNA probes were synthesized by PCR. Because of this nonspecific band, an alternative CYP2B RNA probe (2.0 kb) was tested [35]. Alternatively, the cDNA probe was labeled by random priming using [32P]dCTP (Amersham, UK).…”

Section: Lag Et Almentioning

confidence: 99%

Expression of Cyp2B1 in Freshly Isolated and Proliferating Cultures of Epithelial Rat Lung Cells

Låg¹,

Becher²,

Samuelsen³

et al. 1996

Experimental Lung Research

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Bronchiolar Clara cells and alveolar type 2 cells of the lung are known to express relatively high levels of P450 enzymes compared to other pulmonary cells. Populations of enriched type 2 cells and Clara cells were isolated from rat lung by a procedure including lung perfusion, protease digestion, centrifugal elutriation, and differential attachment. Alveolar macrophages were removed by lavage. The purity of the type 2 cell-enriched population was approximately 90%, and the purity of the Clara cell-enriched population was 40-50%. Both type 2 cells and the cells of the Clara cell-enriched population proliferated in culture. CYP2B1 mRNA was expressed approximately to the same level in type 2 cells and the Clara cell-enriched population. The mRNA levels remained roughly constant for both cell types throughout the culture period, except for an early transient reduction. The apoenzyme level of CYP2B1 was 2-3 times higher in freshly isolated cells of the Clara cell-enriched population than in the type 2 cells. Both epithelial cell types showed decreased level of CYP2B1 apoenzyme in culture. The differences in the CYP2B1 mRNA and apoenzyme expression levels in freshly isolated cells and cultured cells suggest the existence of a post-transcriptional regulatory mechanism for CYP2B1 expression in lung cells. The characterization of specific functions of lung cells in culture, such as P450 gene expression, provides necessary information for the use of the cells in in vitro pulmonary toxicology.

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Induction of cytochrome P‐450 b, e‐type isozymes by polychlorionated biphenyls in rat liver

Cited by 9 publications

References 46 publications

Ethanol-, fasting-, and aceton-inducible cytochromes P-450 in rat liver: regulation and characteristics of enzymes belonging to the IIB and IIE gene subfamilies

Ethanol-, fasting-, and aceton-inducible cytochromes P-450 in rat liver: regulation and characteristics of enzymes belonging to the IIB and IIE gene subfamilies

Factors affecting the mitotic stability of high-copy-number integration into the ribosomal DNA of Saccharomyces cerevisiae

Expression of Cyp2B1 in Freshly Isolated and Proliferating Cultures of Epithelial Rat Lung Cells

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