Construction And Acharacteristics Analysis Of Genome-wide MicroRNA Expression Profile In Down Syndrome Fetus

Objective: To investigate the expression characteristics of miRNAsduring the development of DS fetuses and to identify whether other newmiRNA genes reside in the human chromosome21.Methods: Six DS and6matched control fetal cord blood mononuclearcells (CBMCs) samples verified by chromosome karyotype were collected.Total RNA was extracted from3DS and3control CBMCs, and equallypooled to construct the small RNA cDNA sequencing library of DS andcontrol group, respectively. And then, the Illumina Solexa high-throughputnucleotide sequencing technology was performed. The results were analyzedwith bioinformatics analysis software and validated by stem-loop RT-PCRwith the remaining samples.Results: The whole genome miRNA expression profile of DS fetus wasestablished. Sixty three candidate novel miRNA genes that encode58mature miRNAs were identified in this study. Significantly, one candidatenew miRNA gene was identified as residing within “Down syndrome criticalregion”(chr21q22.2-22.3) of human chromosome21. The chromosomedistribution of expressed miRNA genes was similar in both samples, but thechromosome distribution of miRNA expression abundance was different: DS group was major scattered in8、16、17and21chromosome, while thenormal group was major scattered in3、8、14、16、17and21chromosome.2208096miRNA reads and243miRNAs were detected in DS fetal CBMCs.Compared with the control,149miRNAs were significantly differentiallyexpressed (fold change>2.0and P-value <0.001), and there were6miRNAsup-regulated and143miRNAs down-regulated. Additionally, base on thisstudy,7of14Hsa21-derived miRNAs were detected,3miRNAs wereover-expressed and4were down-expressed in DS CBMCs compared withthe control. Gene ontology enrichment analyses revealed that a set ofabnormally expressed miRNAs were major involved in regulation oftranscription, gene expression, cellular biosynthetic process, and nucleicacid metabolic process. Importantly, most of the mRNA targets in thesecategories were associated with immune modulation (i.e., SOD1, MXD4,PBX1, BCLAF1, and FOXO1).Conclusions: The DS fetal CBMCs have its own specific miRNAexpression profiles and chromosome distribution characteristics.Abnormally expressed miRNAs may be involved in the immune deficiencyof DS fetus, and the decrease of T/B lymphocytes in DS fetal circulation.Furthermore, the significantly dysregulated and specifically expressedmiRNAs are potential prenatal diagnosis biomarkers for DS fetus.