Developmentally regulated cytochrome P-450IA1 expression in cultured rat vascular smooth muscle cells

• Published in: The Journal of biological chemistry Vol. 266; no. 6; pp. 3981 - 3986
• Main Authors: Giachelli, C M, Majesky, M W, Schwartz, S M
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 25.02.1991; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Base Sequence; Biological and medical sciences; Blotting, Northern; Cycloheximide - pharmacology; Cytochrome P-450 Enzyme System - genetics; Cytochrome P-450 Enzyme System - metabolism; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation - drug effects; Male; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Muscle, Smooth, Vascular - enzymology; Rats; Rats, Inbred Strains; RNA, Messenger - genetics; Species Specificity; Transcription, Genetic; Cell culture; Embryonic development; Molecular hybridization; Stability; Rat; Transcription; Growth; Enzyme; Rodentia; Smooth muscle; Transcription repressor; Gene expression; Northern blotting; Vertebrata; Mammalia; Messenger RNA; Molecular probe; Quantitative analysis
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)67890-7

We have examined the expression of cytochrome P-450IA1 (CypIa1) in cultured rat arterial smooth muscle cells (SMC). We report here that newborn (pup) aortic and adult carotid neointimal SMC express 10-20-fold higher steady-state levels of CypIa1 mRNA compared with identically treated SMC derived from adult aorta or uninjured carotid media, respectively. Nuclear transcription experiments suggest that the difference in basal expression of CypIa1 reflects differences in transcription rates of the gene in these two cell types. Treatment of adult aortic SMC with cycloheximide dramatically elevated CypIa1 mRNA levels and had little effect on the amount of this mRNA in pup SMC. That the cycloheximide effect in adult SMC was due to enhanced transcription of the CypIa1 gene was demonstrated by 1) the ability of actinomycin D to completely block the cycloheximide-induced increase in steady-state mRNA levels, and 2) the increased transcription rate of the CypIa1 gene in cycloheximide-treated adult nuclei determined via nuclear transcription assays. Treatment of either cell type with beta-napthoflavone increased CypIa1 mRNA levels to a similar extent, suggesting that the differential response to cycloheximide was specific and not a general lack of pup SMC to respond to transcriptional inducers of the CypIa1 gene. Our data suggest that a labile repressor of the CypIa1 gene is present in cultured adult aortic SMC and is absent, inactive, or at a greatly reduced level in cultured pup SMC.