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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Biosciences & Biotechnology Laboratory » Research » Publications at this Location » Publication #352104
Title: Potential miRNA regulators of differential HPG axis gene expression between low egg producing and high egg producing turkey hens

Author
item BRADY, KRISTEN - University Of Maryland
item LIU, HSIAO-CHING - North Carolina State University
item HICKS, JULIE - North Carolina State University
item Kahney, Gabrielle
item PORTER, TOM - University Of Maryland

Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/10/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Expression differences exist in key genes of the hypothalamo-pituitary-gonadal (HPG) axis in low egg producing hens (LEPH) and high egg producing hens (HEPH); however, regulation of these differences is unknown. MicroRNAs (miRNAs) are small non-coding RNAs that play a role in post-transcriptional regulation by blocking translation or targeting mRNA degradation, causing lower levels of the target protein. MicroRNAs, potentially involved in the regulation of the HPG axis, were assessed in LEPH and HEPH. MiRanda, a miRNA target prediction algorithm, was used to scan HPG axis genes that were differentially expressed between LEPH and HEPH for possible miRNA binding sites. The hypothalamus, pituitary, and the granulosa layers of the largest follicle (F1G) and fifth largest follicle (F5G) were sampled from LEPH and HEPH (n=3/group). Expression of miRNAs with predicted binding sites was examined in each tissue by reverse transcription quantitative PCR. Data were analyzed with a two-way ANOVA using the mixed models procedure of SAS. Potential regulatory miRNA were identified first by significant expression differences in LEPH and HEPH and second by an inverse relationship with levels of their predicted mRNA target (p<0.05). In the hypothalamus, miR-7464-3p, miR-222a, and miR-222b-3p were increased in HEPH, in comparison to LEPH, and were identified as possible regulators for the lower gonadotropin inhibitory hormone (GNIH) levels seen in HEPH in contrast with LEPH (p<0.05). Also, miR-1794 and miR-222a, with predicted progesterone receptor (PGR) binding, were up-regulated in HEPH, while PGR was down-regulated in HEPH (p<0.05). In the pituitary, miR-1650-5p, miR-1658-3p, miR-1644, and miR-1587 were predicted to bind gonadotropin inhibitory hormone receptor (GNIHR) mRNA and showed higher expression in HEPH, inversely correlating with lower expression of GNIHR in HEPH (p<0.05). In the F1G, predicted miRNA expression between HEPH and LEPH did not relate with previous mRNA expression differences (p>0.05). In the F5G, miRNAs predicted to bind steroidogenic acute regulatory protein (STAR) and cholesterol side chain cleavage enzyme (CYP11A1), miR-1466 and miR-1658-3p, showed increased expression in HEPH, coupled with decreased expression of STAR and CYP11A1 in HEPH (p<0.05). Moreover, expression of miR-6688-3p, predicted to bind luteinizing hormone receptor (LHCGR), was up-regulated in HEPH, compared with down-regulation of LHCGR in HEPH (p<0.05). Validation of candidate regulatory miRNA by luciferase reporter assays is vital to further understand the input of the identified miRNAs to differential HPG axis gene expression seen in LEPH and HEPH.