ESPE Abstracts

Introduction: The placenta is an endocrine organ vital to fetal growth. It has multiple functions: pregnancy maintenance, nutrient and oxygen transport to the fetus, and removal of waste products among other functions. MicroRNAs (miRNAs) and proteins are significant mediators of these functions. A description of their global expression in healthy placenta may increase our understanding of the molecular biological pathways that are important for normal fetal growth and development. The aims of this study were to explore the global expression of both miRNAs and proteins in the same samples of human term healthy placenta and to describe involved pathways.

Methods: Nineteen term placenta samples from healthy women with uncomplicated pregnancies were identified in a local sample collection. The samples were derived from uncomplicated vaginal deliveries with healthy normal weight new-borns (5 females). Next generation sequencing and nano-scale liquid chromatographic tandem mass spectrometry were used for the analyses of miRNA and protein expression, respectively. Ingenuity Pathway Analysis was used for functional bioinformatics analyses.

Results: A total of 895 mature miRNAs and 6,523 proteins were detected in the placenta samples, whereof 123 miRNAs and 346 proteins were highly abundant. The miRNAs were in high degree mapped to chromosomes 19, 14 and X. The most abundant proteins served as enzymes (23%), transporters (10%) or transcription regulators (8%). Of the 20 most significant downstream functions for the highly expressed miRNAs and proteins, respectively, eight shared functions were found, namely Cellular function and maintenance, Cell death and survival, Cell-to-cell signaling and interaction, Cellular assembly and organization, Organismal development, Digestive system development and function, Hepatic system development and function, and Inflammatory response.

Discussion: As far as we know, this is the first study presenting both global miRNA and protein expression in the same placenta sample set from healthy term pregnancies. Two of the chromosomes found to have high presence of miRNA genes in the present study are known to contain placenta-specific miRNA clusters (chromosomes 14 and 19), while chromosome X might have been identified here since it has a higher density of miRNA genes than autosomes. The biological functions for the miRNAs and proteins point at basic cellular actions and clearly illustrate that development is an important task during fetal life. Profound knowledge of miRNA and protein expression in healthy placenta can improve the management of aberrant fetal growth and development.