Lopez-Solache I, Luu-The V, Séralini G E, Labrie F
Medical Research Council Group in Molecular Endocrinology, CHUL Research Center, Quebec, Canada.
Biochim Biophys Acta. 1996 Mar 1;1305(3):139-44. doi: 10.1016/0167-4781(95)00198-0.
Primer extension analysis reveals the presence of different forms of mRNA species for rat type I 5 alpha-reductase. Using a 5 alpha-reductase cDNA probe to screen the rat liver lambda gt11 cDNA library, we isolated cDNA clones that have 4 additional amino acids in the NH2-terminal region as compared with the previously reported sequence for rat type I 5 alpha-reductase. These four additional amino acids elongate the rat type I 5 alpha-reductase amino acid sequence to 259 amino acids, the same number as in human type I 5 alpha-reductase, with which it shares 60% identity. Expression of the long and short rat type I 5 alpha-reductase by transfection in human adrenal adenocarcinoma cells, SW-13 cells, indicated that the long cDNA encoded a protein with a higher affinity for the substrate than the short cDNA. To determine the effect of pituitary hormones and dihydrotestosterone (DHT), the mRNA levels in the livers of rats treated with pituitary implants, hypophysectomized, castrated, and castrated coupled with DHT treatment were quantified by dot-blot hybridization assay using rat type I 5 alpha-reductase cDNA as probes. The results demonstrated that rat type I 5 alpha-reductase mRNA is stimulated by pituitary hormones and castration but is decreased by DHT and hypophysectomy.
引物延伸分析揭示了大鼠I型5α-还原酶存在不同形式的mRNA种类。我们用5α-还原酶cDNA探针筛选大鼠肝脏λgt11 cDNA文库，分离出的cDNA克隆在NH2末端区域比先前报道的大鼠I型5α-还原酶序列多4个氨基酸。这4个额外的氨基酸使大鼠I型5α-还原酶的氨基酸序列延长至259个氨基酸，与人类I型5α-还原酶的氨基酸数量相同，二者的同源性为60%。通过转染人肾上腺腺癌细胞SW-13细胞来表达大鼠I型5α-还原酶的长型和短型，结果表明，长型cDNA编码的蛋白比短型cDNA编码的蛋白对底物具有更高的亲和力。为了确定垂体激素和双氢睾酮（DHT）的作用，以大鼠I型5α-还原酶cDNA为探针，通过斑点杂交试验对垂体植入、垂体切除、去势以及去势并给予DHT处理的大鼠肝脏中的mRNA水平进行了定量分析。结果表明，大鼠I型5α-还原酶mRNA受垂体激素刺激和去势的影响，但受DHT和垂体切除的抑制。
