Cloning and sequence analysis of the cDNA encoding P-450 aromatase (P450arom) from a rainbow trout (Oncorhynchus mykiss) ovary; relationship between the amount of P450arom mRNA and the production of oestradiol-17β in the ovary

Abstract

The enzyme aromatase P-450 (P450arom) catalyses the conversion of androgen to oestrogen. A cDNA insert encoding P450arom was isolated from a rainbow trout (Oncorhynchus mykiss) ovary cDNA library. The insert was sequenced and found to contain an open-reading frame predicted to encode a protein of 522 amino acid residues. The deduced polypeptide is 52% homologous with human, mouse and rat P450arom and 53% homologous with that of chicken. The insert was confirmed to encode P450arom by introducing it into COS-1 monkey kidney tumour cells (COS-1 cells) and detecting the conversion of testosterone to oestradiol-17 beta by radioimmunoassay. The N-terminal region of the deduced polypeptide was 19 amino acids longer than that of the other four species, and was found by hydropathy plotting to be very hydrophobic. Northern blot analysis revealed 2.6 kb RNA transcripts which were present in the trout ovary during vitellogenesis and hybridized to the cDNA insert. In preparations from subsequent stages of ovarian development, no RNA transcripts hybridized to the probe. Since the RNA transcripts are present only during the stage of oestradiol-beta production by the ovarian follicles, oestradiol-17 beta production may be regulated, in part, by the amount of P450arom mRNA present.

Celebrating 75 years of oestradiol

“…Use of 5 0 -RACE led to the characterization of the sequence of the 5 0 -end of the cDNA, thus yielding the entire cDNA and amino acid sequence of the human aromatase protein, with a total of 503 amino acids and a molecular weight of 58 kDa. Subsequently, similar techniques identified aromatase sequences from numerous species (Corbin et al 1988, Harada 1988, Toda et al 1989, Hickey et al 1990, Terashima et al 1991, Tanaka et al 1992). …”

Ovarian 3,β‐hydroxysteroid dehydrogenase/Δ5‐4‐isomerase of rainbow trout: Its cDNA cloning and properties of the enzyme expressed in a mammalian cell

“…Rainbow trout ovarian follicular poly(A) + RNA was prepared as described previously [10]. Hybridization was carried out with 32P-labeled entire trout 3fl-HSD cDNA by the Multiprime DNA labeling system described previously [6].…”

Two cytochrome P450 aromatase genes in the hermaphrodite ricefield eel Monopterus albus: mRNA expression during ovarian development and sex change

“…In mammals, with the exception of pig (Choi et al 1997, Graddy et al 2000, CYP19 is encoded by a single copy of the CYP19 gene, and the tissuespecific expression was achieved by the use of tissue-specific promoters and alternative splicing of 5 0 untranslated exons (Simpson 2003). However, two distinct CYP19 genes, namely cyp19a1a and cyp19a1b, which were expressed mainly in the ovary and brain respectively, were identified in teleosts, such as Carassius auratus (Tchoudakova & Callard 1998), Oncorhynchus mykiss (Tanaka et al 1992, Valle et al 2002, Danio rerio (Kishida & Callard 2001), Oreochromis niloticus (Kwon et al 2001), Dicentrarchus labrax (Blázquez & Piferrer 2004), Halichoeres tenuispinis (Choi et al 2005), Fundulus heteroclitus (Greytak et al 2005), and Epinephelus coioides (Zhang et al 2004). In fishes such as rainbow trout and tilapia, the expression of cyp19a1a was shown to be crucial for ovarian differentiation (Guiguen et al 1999).…”