Tissue-specific and hormonally controlled alternative promoters regulate aromatase cytochrome P450 gene expression in human adipose tissue

• Published in: The Journal of biological chemistry 1993-09, Vol.268 (26), p.19463-19470
• Main Authors: MAHENDROO, M. S, MENDELSON, G. R, SIMPSON, E. R
• Format: Article
• Language: English
• Subjects: Adipose Tissue - enzymology; Alternative Splicing; Amino Acid Sequence; Aromatase - biosynthesis; Aromatase - genetics; Base Sequence; Biological and medical sciences; Blotting, Northern; Breast - enzymology; Cells, Cultured; DNA; Exons; Female; Fundamental and applied biological sciences. Psychology; Gene Expression; Gene Expression Regulation, Enzymologic; Humans; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Oligodeoxyribonucleotides; Organ Specificity; Poly A - genetics; Poly A - isolation & purification; Polymerase Chain Reaction; Promoter Regions, Genetic; Protein Biosynthesis; Restriction Mapping; RNA - genetics; RNA - isolation & purification; RNA, Messenger; Transcription, Genetic; Transcription. Transcription factor. Splicing. Rna processing
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/s0021-9258(19)36538-x

Estrogen biosynthesis is catalyzed by a microsomal enzyme, aromatase cytochrome P450 (P450arom; the product of the CYP19 gene). The human CYP19 gene comprises nine coding exons, II-X. Additionally, tissue-specific expression is determined by the use of tissue-specific promoters, which give rise to P450arom transcripts with unique 5'-noncoding sequences. In placenta, P450arom transcripts contain one of two 5'-untranslated exons, I.1 or I.2, while ovarian transcripts instead contain sequence consistent with the use of a promoter, PII, which is proximal to the start of translation. To characterize transcripts present in adipose tissue and adipose stromal cells (ASC) in culture, cDNA libraries were constructed by the RACE (rapid amplification of cDNA ends) procedure. Four P450arom transcripts with unique 5' termini were identified, leading to the characterization of two unique 5'-untranslated exons of the CYP19 gene, I.3 and I.4. Whereas I.3-specific sequence is expressed in adipose tissue as well as in ACS maintained under all culture conditions, I.4-specific sequence is apparently present only in breast adipose tissue, and ACS stimulated with glucocorticoids. On the other hand, PII-specific sequence is present only in cells stimulated with cAMP analogues and is absent from cells stimulated with glucocorticoids. We conclude that CYP19 gene expression in human adipose tissue likely utilizes two novel promoters and, furthermore, that alternative promoter usage in cultured ASC is a function of the hormonal environment in which the cells are maintained.