307. microRNAs ARE DIFFERENTIALLY EXPRESSED BETWEEN MID AND LATE GESTATION AND IN DIFFERENT FUNCTIONAL ZONES OF THE RAT PLACENTA
W. Kong A , S. Moretta A , P. A. Grant A , M. Dziadek B and J. A. Owens AA Obstetrics and Gynaecology, University of Adelaide, Adelaide, SA, Australia.
B Garvan Institute of Medical Research, Sydney, NSW, Australia.
Reproduction, Fertility and Development 22(9) 107-107 https://doi.org/10.1071/SRB10Abs307
Published: 6 September 2010
Abstract
MicroRNAs (miRNAs) are short, single-stranded, non-coding RNAs that regulate translation, by interacting with complementary sites in the 3′UTRs of target mRNAs. Each can target multiple mRNAs and each mRNA can be targeted by many different miRNAs to form regulatory networks. Placental development is characterised by dynamic, co-ordinated changes in expression of regulatory and functional genes that drive invasion, differentiation and growth. These changes may involve miRNAs, but placental miRNA expression during gestation has been little studied in any species to date. MiRNA expression was examined (by microarray) in the rat in mid (day 16) and late (day 20) gestation (term ~22 days) and the two major zones of the placenta, the labyrinth and junctional zones, at and between each gestational age. At day 16, 107 miRNAs were differentially expressed between the labyrinth and junctional zone (P < 0.05); 47% being more highly expressed and the remainder less expressed in the labyrinth compared to the junctional zone. At day 20, 78 miRNAs were differentially expressed between the two zones (P < 0.05); 53% being higher and the remainder lower in the labyrinth compared to the junctional zone. 216 miRNAs were differentially expressed in the labyrinth zone between mid and late gestation; 73% of the differentially expressed labyrinth zone miRNAs were upregulated at day 20, many from a cluster on chromosome 6, a feature of the late gestation mouse placenta as well (Kong et al., unpublished). In the mouse, these same clustered miRNAs are located on chromosome 12 in an imprinted region, with the miRNAs expressed from the maternal allele. Disruption of their expression impairs placental vascular, labyrinth and junctional zone development [1]. Together these findings imply that these clustered miRNAs are likely to play a role in labyrinth zone development and further study is warranted into which placental transcripts are targeted by these imprinted miRNAs.
(1) Georgiades P, et al., Parental origin-specific developmental defects in mice with uniparental disomy for chromosome 12. Development, 2000. 127(21): 4719–28.
