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Biol Sex Differ. 2018 Jan 15;9(1):4. doi: 10.1186/s13293-018-0165-y.

Sex differences in the late first trimester human placenta transcriptome.

Author information

1
Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
2
Center for Public Health Genomics, University of Virginia, Charlottesville, VA, USA.
3
Division of Reproductive Endocrinology and Infertility, UCLA David Geffen School of Medicine, Los Angeles, CA, USA.
4
Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
5
LABiomed/Harbor-UCLA Medical Center, Torrance, CA, USA.
6
Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
7
Department of Obstetrics and Gynecology, Division of Reproductive Endocrinology and Infertility, Cedars-Sinai Medical Center, Los Angeles, CA, USA. Margareta.Pisarska@cshs.org.
8
Division of Reproductive Endocrinology and Infertility, UCLA David Geffen School of Medicine, Los Angeles, CA, USA. Margareta.Pisarska@cshs.org.

Abstract

BACKGROUND:

Development of the placenta during the late first trimester is critical to ensure normal growth and development of the fetus. Developmental differences in this window such as sex-specific variation are implicated in later placental disease states, yet gene expression at this time is poorly understood.

METHODS:

RNA-sequencing was performed to characterize the transcriptome of 39 first trimester human placentas using chorionic villi following genetic testing (17 females, 22 males). Gene enrichment analysis was performed to find enriched canonical pathways and gene ontologies in the first trimester. DESeq2 was used to find sexually dimorphic gene expression. Patient demographics were analyzed for sex differences in fetal weight at time of chorionic villus sampling and birth.

RESULTS:

RNA-sequencing analyses detected 14,250 expressed genes, with chromosome 19 contributing the greatest proportion (973/2852, 34.1% of chromosome 19 genes) and Y chromosome contributing the least (16/568, 2.8%). Several placenta-enriched genes as well as histone-coding genes were identified to be unique to the first trimester and common to both sexes. Further, we identified 58 genes with significantly different expression between males and females: 25 X-linked, 15 Y-linked, and 18 autosomal genes. Genes that escape X inactivation were highly represented (59.1%) among X-linked genes upregulated in females. Many genes differentially expressed by sex consisted of X/Y gene pairs, suggesting that dosage compensation plays a role in sex differences. These X/Y pairs had roles in parallel, ancient canonical pathways important for eukaryotic cell growth and survival: chromatin modification, transcription, splicing, and translation.

CONCLUSIONS:

This study is the first characterization of the late first trimester placenta transcriptome, highlighting similarities and differences among the sexes in ongoing human pregnancies resulting in live births. Sexual dimorphism may contribute to pregnancy outcomes, including fetal growth and birth weight, which was seen in our cohort, with males significantly heavier than females at birth. This transcriptome provides a basis for development of early diagnostic tests of placental function that can indicate overall pregnancy heath, fetal-maternal health, and long-term adult health.

KEYWORDS:

Chorionic villus sampling; First trimester placenta; Pregnancy; RNA-sequencing; Sex differences

PMID:
29335024
PMCID:
PMC5769539
DOI:
10.1186/s13293-018-0165-y
[Indexed for MEDLINE]
Free PMC Article

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