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Thyroid hormone receptors de novo transcription is essential for early bovine embryo development in vitro
Thyroid hormone receptors alpha and beta (THR α and β) mediate the genomic action of thyroid hormones (THs) that affect bovine embryo development. However, little is known about THRs in the preimplantation embryo. The objective of this study was to investigate the importance of THRs in in vitro preimplantation bovine embryos. THRs transcripts and protein levels were detected in developing preimplantation embryos up to blastocyst. THRs embryonic transcription was inhibited by α-amanitin supplementation and both maternal and embryonic transcription were knocked down by siRNA micro-injection. Results in control group show both THRs mRNA and protein level increase after the fertilization. Contrary, both transcription inhibition and knock down groups confirmed significant (p<0.05) decrease in THRs mRNA from 2-cell stage onwards. . However, THRs protein levels was not altered at 2-cell stage, but exhibited a significant (p<0.05) decrease from the 4-cell stage. Moreover, inhibition of de novo transcripts of THRs using siRNA led to a significant (p< 0.01) decrease in the developmental rate, cell number and change in embryo morphology. In conclusion, THRs are transcribed soon after fertilization, before the major activation of the embryonic genome, and that they are essential for bovine embryo development in vitro.
RD17165 Accepted 18 October 2017
© CSIRO 2017