Tissue-specific and hormonally controlled alternative promoters regulate aromatase cytochrome P450 gene expression in human adipose tissue.
Tissue-specific and hormonally controlled alternative promoters regulate aromatase cytochrome P450 gene expression in human adipose tissue.
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DOI：
10.1016/s0021-9258(19)36538-x
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发表时间：
1993-09
期刊：
影响因子：
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通讯作者：
M. Mahendroo;C. Mendelson;E. Simpson;E. Simpson
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文献类型：
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作者：
M. Mahendroo;C. Mendelson;E. Simpson;E. Simpson
雌激素的生物合成是由微粒体酶细胞色素P450(P450arom；CYP19基因的产物)催化的。人类CYP19基因由9个编码外显子II-X组成。此外，组织特异性表达是由组织特异性启动子的使用确定的，这导致P450arom转录本具有独特的5‘-非编码序列。在胎盘中，P450arom转录本包含两个5‘-未翻译外显子之一，I.1或I.2，而卵巢转录本则包含与启动子PII的使用一致的序列，PII位于翻译开始的最近端。为了鉴定脂肪组织和培养的脂肪基质细胞(ASC)中存在的转录本，采用RACE(快速扩增cDNAEnds)程序构建了cDNA文库。鉴定了四个具有独特5‘末端的P450arom转录本，从而确定了CYP19基因的两个独特的5’-未翻译外显子I.3和I.4。I.3特异性序列在脂肪组织和在所有培养条件下维持的ACS中都有表达，而I.4特异性序列显然只存在于乳房脂肪组织中，并且在糖皮质激素刺激下的ACS中表达。另一方面，PII特异性序列只存在于cAMP类似物刺激的细胞中，而不存在于糖皮质激素刺激的细胞中。我们得出结论，在人类脂肪组织中，CYP19基因的表达可能利用了两个新的启动子，而且，在培养的ASC中，替代启动子的使用是细胞维持的激素环境的函数。
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.