Holmes/Van Bakel/Jabs. Transcriptome Atlases of the Craniofacial Sutures

Craniofacial sutures are the fibrous joints between bones, allowing growth of the skull from prenatal to postnatal development until adult size is achieved. Proper suture development is crucial because abnormal suture fusion can require major surgical intervention to restore a satisfactory head and facial appearance and to prevent secondary damage to the brain, eyes, hearing, breathing, and mastication. Craniosynostosis, the premature fusion of skull sutures, is a common birth defect, occurring in 1/2500 live births. It may present in syndromic and non-syndromic forms, and while mutations in some of the genes that account for syndromic forms are known, the underlying genetic etiology has not been identified for the majority of cases that are nonsyndromic and involve a single suture. A more comprehensive understanding of suture biology and pathology can be aided by knowledge of gene expression profiles of sutures. Craniofacial sutures vary widely in form, function, and susceptibility to fusion, suggesting that gene expression profiles vary considerably among sutures and during different developmental stages. A detailed characterization of gene expression would require the extraction of specific populations of cells from the different subregions of each suture, including the non-ossifying suture mesenchyme and the flanking osteogenic bone fronts, which are often from distinct bones and may therefore have distinct gene expression patterns. Our overall goal is to generate comprehensive gene expression atlases of the major and functionally important craniofacial sutures of the mouse, which will accelerate both our understanding of human suture biology and the discovery of candidate genes whose mutation may cause craniosynostosis or other defects of craniofacial bone development. We will apply the state-of-the-art technology of laser capture microdissection to obtain tissue from different craniofacial sutures of both normal and craniosynostotic mouse models, combined with next generation sequencing of extracted RNA to generate bulk RNA-Seq expression atlases. In addition, we will generate single cell RNA-Seq libraries of WT calvarial sutures during embryonic and postnatal development.