1Anthropology, Virginia Commonwealth University, 2Surgery, Virginia Commonwealth University
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Non-syndrome associated premature fusion of one or more cranial sutures, isolated craniosynostosis, has a prevalence of 1 in 2500 births. The molecular mechanisms of patency and fusion have not been fully elucidated. Formation of calvarial bones occurs through intramembranous ossification where mesenchymal cells proliferate and differentiate into osteoblasts at the osteogenic front. The developing osteogenic front is tightly regulated by precisely timed gene expression. With only 1.5% of the genome coding for proteins regulatory non-coding RNAs are significant contributors to variability. The purpose of this research was to measure both mRNA and regulatory miRNA expression in nonsyndromic craniosynostosis (NSC) and identify those differentially expressed to better understand calvarial morphogenesis and suture patency.
RNA was isolated from paired cranial suture fragments of infants undergoing cranial reconstruction for NSC. Expression levels for both mRNA and miRNA expression were measured for 14 samples (7 paired fused/patent) using Illumina’s BeadArray platform. Raw data was processed using Illumina’s GenomeStudio 2010v.3. Probe set signals were normalized using the Quantile method. Differential expression was measured using Illumina’s Custom Model, FlexArray, and GeneSifter. Three different tests were applied: Log2 Fold changes, Bayes T test, and Wilcoxon Rank Sum.
We identified 32 significantly differentially expressed miRNAs and 106 mRNAs in fused compared with patent sutures. Additionally, there was a negative correlation between several miRNAs predicted to target multiple genes that negatively regulate osteogenesis. These data are a step forward towards the understanding of the proximate molecular mechanisms involved in maintaining suture patency and the transcriptome of calvarial sutures.
This study was supported by a grant from Richmond Eye & Ear Healthcare Alliance, Richmond, VA.