Aromatase cytochrome P450 in rat ovarian granulosa cells before and after luteinization: adenosine 3',5'-monophosphate-dependent and independent regulation. Cloning and sequencing of rat aromatase cDNA and 5' genomic DNA.
Mol Endocrinol
; 4(1): 3-12, 1990 Jan.
Article
em En
| MEDLINE
| ID: mdl-2157976
ABSTRACT
The complete nucleotide sequence for rat ovarian aromatase cytochrome P450 (P450arom) has been derived from four cDNA clones isolated from three rat granulosa/luteal cell lambda gt11 cDNA expression libraries. The composite P450arom cDNA extends 1597 basepairs, encodes a protein of 508 amino acids (calculated mol wt = 58,263), and hybridizes to three mRNA transcripts (3.3, 2.6, and 1.9 kilobases in size) in rat ovarian tissues. A 5' genomic fragment was isolated from a rat genomic library and shown to contain exon I and 538 basepairs of 5' flanking sequences, including putative promoter elements. Further, we document that P450arom mRNA and estradiol (E) biosynthesis are regulated by cAMP-dependent mechanisms in granulosa cells of preovulatory (PO) follicles, but are maintained by cAMP-independent mechanisms after LH/hCG-induced luteinization. The transition of the PO granulosa cell to the luteal cell (PO + hCG) phenotype requires 5 h of exposure to hCG in vivo. Once the luteal cell phenotype is programed, P450arom mRNA and E biosynthesis are maintained in the luteinized cells for up to 10 days in a constitutive manner in the absence of hormones or agents that increase intracellular cAMP. Furthermore, when PO + hCG (7 h) follicles were isolated and incubated for 1-3 h with reversible inhibitors of transcription (actinomycin-D) or translation (cycloheximide) before harvesting the granulosa cells, neither morphological nor functional luteinization of granulosa cells in culture was impaired. Thus, rapid cellular and molecular events occur in granulosa cells within 5-7 h after an ovulatory LH/hCG surge that alter the hormonal regulation of the aromatase gene.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
DNA
/
Aromatase
/
AMP Cíclico
/
Gonadotropinas Hipofisárias
/
Células da Granulosa
Limite:
Animals
/
Female
/
Humans
Idioma:
En
Revista:
Mol Endocrinol
Assunto da revista:
BIOLOGIA MOLECULAR
/
ENDOCRINOLOGIA
Ano de publicação:
1990
Tipo de documento:
Article