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ARS Home » Research » Publications at this Location » Publication #47288
Title: FUNCTIONAL AROMATASE EXPRESSION IN PORCINE ADRENAL GLAND AND TESTIS

Author
item CONLEY, ALAN - NORTH DAKOTA STATE UNIV
item CORBIN, C - NORTH DAKOTA STATE UNIV
item HINSHELWOOD, M - SOUTHWESTERN MED CTR, TX
item LIU, Z - UNIV TX SOUTHWESTERN MED
item SIMPSON, E - UNIV TX SOUTHWESTERN MED
item FORD, JOHNY - 5438-01-10
item HARADA, N - FUJITA HEALTH UNI, JAPAN

Submitted to: Biology of Reproduction
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Estrogens are synthesized by a single enzyme, P450 aromatase, in porcine blastocysts, placenta, fetal adrenals, testes and ovaries. Studies were conducted to determine if this enzyme is regulated by similar means in these divergent tissues. Three distinct forms of messenger RNA for P450 aromatase were identified. One form was unique to placenta and blastocyst; a second was unique to ovaries and the third was unique to testes and adrenals. These studies determined that porcine P450 aromatase is regulated differently in different tissues by a single gene through tissue-specific transcription. These observations will impact the design of subsequent studies.

Technical Abstract: Tissue-specific expression of cytochrome P450 aromatase (P450arom) was investigated by northern and western analyses in porcine blastocysts, placenta, fetal adrenal, fetal testis, and theca and granulosa tissues from preovulatory follicles. The identity of P450arom transcripts was confirmed by sequence analysis of partial cDNA clones. This analysis recognized distinct differences among the transcripts which involved both the 5' untranslated and translated regions. Divergence of sequences occurred at -39 bp, and proximal to this site, three specific 5' ends were identified, representing placenta/blastocyst, theca/granulosa and fetal adrenal/fetal testes. This indicates that at least three tissue-specific promoters direct P450arom expression in the pig. Only the ovary-specific sequence exhibited homology (76%) with tissue-specific exons characterized for human P450arom in this untranslated region of the transcript. Differences were also noted in the coding region of placental clones compared with those from other tissues which predicted a two amino acid deletion and 12 predicted amino acid substitutions within the first presumptive coding exon of cDNAs isolated from theca, granulosa, fetal adrenal and fetal testis. P450arom activity detected in homogenates of all tissues was inhibited by 4-hydroxyandrostenedione but inhibition was also demonstrated by etomidate in all tissues except placenta. These data provide structural and functional evidence for the existence of tissue- specific isoforms of P450arom in pigs, one of which is expressed in the adrenal gland of fetal pigs and that expression of P450arom in pigs may be controlled in part by alternate splicing of tissue-specific untranslated exons.