A developmental switch in expression from blastocyst to endometrial/placental-type cytochrome P450 aromatase genes in the pig and horse.
Abstract: Pig blastocysts exhibit a transient period of estrogen production at periimplantation, with a second, more sustained period of estrogen synthesis occurring in endometrium and placenta at later pregnancy. Previously we reported the isolation of cDNA clones encoding a novel isoform of cytochrome P450 aromatase (the terminal enzyme in the estrogen biosynthetic pathway) from porcine periimplantation blastocysts. The present study investigated pregnancy-associated expression, in blastocysts and maternal reproductive tract tissues of this and an additional mRNA transcript encoding a distinct P450 aromatase isoform. Restriction endonuclease and nucleotide sequence analyses of 44 cDNA clones demonstrated that the major aromatase mRNA in periimplantation blastocysts and early-pregnancy endometrium and placenta (blastocyst-type) differed in sequence from the major aromatase mRNA expressed in endometrium and placenta at midpregnancy (endometrial-type). The deduced blastocyst and endometrial aromatase isoform protein sequences had 93% similarity. A third type of aromatase mRNA, deleted in exons 4-6 sequences, also was cloned from blastocysts. This cDNA was identical in nucleotide sequence to the blastocyst full-length aromatase cDNA and specified an open reading frame of 354 amino acids for a putative aromatase-related protein containing the heme-binding domain. Expression of this shorter mRNA in blastocysts was confirmed by reverse transcription polymerase chain reaction. The 5'-untranslated exon sequences in the transcripts encoding the blastocyst-type aromatase isoform were distinct from that of the endometrial type, consistent with differential expression of multiple chromosomal genes. In periimplantation equine embryos, however, embryonic and placental 5'-untranslated exon-containing transcripts were coexpressed. Results identify an aromatase isoform expressed in the endometrium and placenta at midpregnancy, demonstrate a transition in synthesis of aromatase isoform-specific mRNAs during placental development, and suggest the preferential involvement of the blastocyst aromatase isoform in synthesis of estrogenic molecules that may function in embryo-maternal signaling at periimplantation.
Publication Date: 1997-03-01 PubMed ID: 9047015DOI: 10.1095/biolreprod56.3.688Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- Non-P.H.S.
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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The study investigates the expression of different forms of cytochrome P450 aromatase, an enzyme crucial for estrogen production, in pig and horse embryos and tissues involved in reproduction during pregnancy. The research identifies a switch in the specific form produced between the early and mid-stages of pregnancy, suggesting possible roles in embryonic signaling and placental development.
Analysis of mRNA Transcripts
- The research extracted 44 cDNA clones from pig blastocysts during and after implantation, and tissues related to reproduction for restriction endonuclease and nucleotide sequence analysis. These clones were used to investigate the expression of two types of mRNA transcripts, which encode different forms of the P450 aromatase enzyme.
- Results showed that the form of the enzyme produced by the blastocysts around implantation differed from the one produced by the endometrium and placenta at the mid-stage of pregnancy. This suggests that the type of enzyme might play different roles at varying stages of pregnancy.
Comparison of Aromatase Isoforms
- The deduced protein sequences for the two versions of the enzyme had a 93% similarity, suggesting a marked, but not complete, overlap in their functionalities.
- An additional third type of mRNA transcript, which lacked certain sequences (exons 4-6), was also cloned from the blastocysts. This also specified a protein related to the P450 enzyme.
Expression of Shorter mRNAs
- The shorter mRNA extracted from the blastocysts was also shown to be expressed by Reverse Transcription Polymerase Chain Reaction, a technique used to create cDNA from mRNA.
- Differences were seen in untranslated regions of the mRNAs encoding each type of the enzyme, suggesting differential expression of different genes. This indicates that different versions of the enzyme are produced under the influence of different regulatory networks.
Equine Observations
- The study also observed equine embryos, noting coexpression of different transcripts in embryonic and placental samples.
- This work identifies an isoform of aromatase expressed in the endometrium and placenta during mid-pregnancy, pointing to a shift in the production of different forms of the enzyme.
- The findings suggest a potential involvement of the blastocyst form of the enzyme in synthesizing estrogens that might play a role in embryonic signaling around implantation.
Cite This Article
APA
Choi I, Collante WR, Simmen RC, Simmen FA.
(1997).
A developmental switch in expression from blastocyst to endometrial/placental-type cytochrome P450 aromatase genes in the pig and horse.
Biol Reprod, 56(3), 688-696.
https://doi.org/10.1095/biolreprod56.3.688 Publication
Researcher Affiliations
- Department of Dairy and Poultry Sciences and the Interdisciplinary Concentration in Animal Molecular and Cell Biology, University of Florida, Gainesville 32611-0920, USA.
MeSH Terms
- Amino Acid Sequence
- Animals
- Aromatase / biosynthesis
- Aromatase / genetics
- Base Sequence
- Blastocyst / enzymology
- Cloning, Molecular
- Endometrium / enzymology
- Endometrium / growth & development
- Female
- Gene Expression Regulation, Developmental / physiology
- Gene Expression Regulation, Enzymologic / physiology
- Horses
- Isoenzymes / biosynthesis
- Isoenzymes / genetics
- Molecular Sequence Data
- Placenta / enzymology
- Placentation
- Polymerase Chain Reaction
- Pregnancy
- RNA, Messenger / biosynthesis
- Swine
Grant Funding
- HD-21961 / NICHD NIH HHS
Citations
This article has been cited 4 times.- de Oliveira FD, Santos PRDS, de Oliveira MF, de Assis AC. Galea spixii embryos have potential to produce steroid hormones.. Anim Reprod 2022;19(4):e20220091.
- Pericuesta E, Laguna-Barraza R, Ramos-Ibeas P, Gutierrez-Arroyo JL, Navarro JA, Vera K, Sanjuan C, Baixeras E, de Fonseca FR, Gutierrez-Adan A. D-Chiro-Inositol Treatment Affects Oocyte and Embryo Quality and Improves Glucose Intolerance in Both Aged Mice and Mouse Models of Polycystic Ovarian Syndrome.. Int J Mol Sci 2020 Aug 22;21(17).
- Conley AJ, Corbin CJ, Hughes AL. Adaptive evolution of mammalian aromatases: lessons from Suiformes.. J Exp Zool A Ecol Genet Physiol 2009 Jun 1;311(5):346-57.
- Gaucher EA, Graddy LG, Li T, Simmen RC, Simmen FA, Schreiber DR, Liberles DA, Janis CM, Benner SA. The planetary biology of cytochrome P450 aromatases.. BMC Biol 2004 Aug 17;2:19.
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