Sex differences in microRNA expression in first and third trimester human placenta†

Area of Science:

• Reproductive biology
• Epigenetics
• Genomics

Background:

• Pregnancy outcomes and placental function exhibit sex-specific variations.
• These differences may stem from sexually dimorphic epigenetic regulation of gene expression, particularly microRNAs (miRNAs).

Purpose of the Study:

• To identify and characterize sexually dimorphic miRNA expression profiles in human placentae across gestation.
• To establish a normative atlas of sex-dimorphic and sex-independent placental miRNA expression throughout pregnancy.

Main Methods:

• Next-generation sequencing was used to profile miRNA expression in human placentae from uncomplicated pregnancies in the first and third trimesters.
• Analysis included identification of differentially expressed miRNAs and pathway enrichment analysis.

Main Results:

• A total of 986 mature miRNAs were identified. Eleven sexually dimorphic miRNAs were found in the first trimester and 4 in the third, all upregulated in females.
• Across gestation, 677 differentially expressed miRNAs were identified, with 508 common between female-specific and male-specific analyses.
• Female placentae showed a higher number of exclusive miRNA expression differences compared to male placentae, indicating significant sexual dimorphism.

Conclusions:

• Human placental miRNA expression is sexually dimorphic throughout gestation.
• The identified miRNA atlas provides a valuable resource for understanding placental function and identifying potential biomarkers for pregnancy complications.