Preovulatory estradiol concentrations influence oviductal gene expression

Authors: QUAIL, LACEY - Texas A&M University; Cushman, Robert - Bob; Keel, Brittney; McNeel, Anthony; GONDA, MICHAEL - South Dakota State University; PERRY, GEORGE - Texas A&M University

Submitted to: Society for the Study of Reproduction Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 10/2/2021
Publication Date: 12/15/2021
Citation: Quail, L.K., Cushman, R.A., Keel, B.N., McNeel, A.K., Gonda, M.G., Perry, G.A. 2021. Preovulatory estradiol concentrations influence oviductal gene expression [abstract]. Society for the Study of Reproduction Annual Meeting, December 15-18, 2021, St. Louis, Missouri. Poster P232.

Interpretive Summary:

Technical Abstract: Behavioral estrus in beef cows is associated with increased circulating concentrations of estradiol and a 27% increase in pregnancy success to artificial insemination (AI) compared to beef cows that did not express behavioral estrus. Considering the oviduct produces factors unique from the uterine environment that directly control the paracrine environment of the developing embryo, the objective of this experiment was to investigate differences in oviductal mRNA expression in animals with high or low circulating concentrations of estradiol at the time of artificial insemination. Beef cows (n = 6) were synchronized using the 7-d CO-Synch protocol with GnRH administration on d-9, PG administration on d-2, and GnRH administration and AI at d0. Daily blood samples were collected from d-9 to d1 to determine circulating estradiol concentrations. Cows were classified as having high or low circulating concentrations of estradiol at the time of AI (High = 10.12 ± 0.62 pg/ml, n = 3; Low = 5.97 ± 0.62 pg/ml, n = 3; P < 0.01). Twenty-four hours after AI, oviducts were collected from cows at slaughter. Total cellular RNA was isolated from the ampullary-isthmic junction and isthmus regions of the oviduct, treated with DNAase, and RNA-seq was performed. Paired end libraries were constructed using Truseq 2.0 RNA-seq library prep kits and sequenced on a Hi-seq 2000. Sequencing reads from cDNA were trimmed using Trimmomatic. Paired end reads were mapped to the reference bovine genome (Bos taurus ARS-UCD1.2) using HISAT2 version 2.2.0. Transcripts were assembled and gene counts were obtained using StringTie version 1.3.3. Differentially expressed genes were identified using DESeq2. Differences in transcript abundance were considered significant when the adjusted FDR P = 0.05. Differentially expressed and annotated genes were then submitted for pathway analysis via DAVID 6.8. At the ampullary-isthmic junction, 1386 genes were up-regulated, and 61 genes were down-regulated in High cows compared to Low cows. At the isthmus region, 349 genes were up-regulated, and 202 genes were down-regulated in High cows compared to Low cows. Perhaps most notably, at the ampullary-isthmic junction, differential gene expression significantly influenced metabolic (P = 2.1 x 10-4), VEGF signaling (P = 5.3 x 10-4), mTOR signaling (P = 5.6 x 10-3), GnRH signaling (P = 6.7 x 10-3), estrogen signaling (P = 9.1 x 10-3), Notch signaling (P = 9.8 x 10-3), and prolactin signaling (P = 1.2 x 10-2) KEGG pathways. With components influencing embryo development, differential gene expression in cows with high circulating concentrations of estradiol significantly influenced focal (P = 8.9 x 10-5) and cell adhesion (P = 5.9 x 10-2) KEGG pathways in the isthmus. In summary, preovulatory estradiol were associated with gene expression in the oviduct that likely influences fertilization and early embryonic development through components of metabolic, growth factor signaling, hormone signaling, and cell adhesion pathways. These pathways are expected to contribute to increased overall pregnancy success observed in animals with high circulating concentrations of estradiol at the time of artificial insemination. USDA is an equal opportunity provider and employer.