Project description:The skull vault is composed of frontal and parietal bones that are connected by flexible sutures that protect the growing brain. Intramembranous ossification in the prenatal skull vault starts by mid-gestation in the mouse, and sutures must remain flexible for normal growth and development. Therefore, the balance of bone formation and remodeling needs to be precisely controlled because premature ossification in the sutures causes craniosynostosis (CS) to develop. CS has a variable clinical presentation where two frontal bones may be fused together, or a frontal bone may be fused to a parietal bone. While most studies focus on the premature suture ossification, we hypothesized that the process of intramembranous ossification in the frontal and parietal bones contributes to the etiology of CS. By bulk RNASeq we identified 536 unique transcripts between the frontal and parietal compartments.Taken together, we propose that the frontal bone is more active in bone remodeling than the parietal bone, and this control is important for temporal onset of intramembranous ossification in the skull vault.
Project description:Purpose: This study investigates the postnatal impact of Twist1 haploinsufficiency on the osteoskeletal ability and regeneration on two calvarial bones arising from tissues of different embryonic origin: the neural crest-derived frontal and the mesoderm-derived parietal bones. Results: Twist1 haplonsufficiency selectively enhanced osteogenic and tissue regeneration ability of mesoderm-derived parietal bones. Twist1 haplonsufficiency triggers its selective activity on mesoderm-derived parietal bone through downregulation of the bone-derived hormone Fgf23. Conclusions: Twist1 haploinsufficiency preferentially triggers osteogenic induction of parietal bones which may be beneficial to optimize treatments for skeletal regeneration, reconstruction and repair of mesoderm-derived bone, as well as to alleviate skeletal abnormalities caused by Twist1 haploinsufficiency.
Project description:Certain bone graft materials are employed for alveolar bone regeneration, and autografts are commonly used. Alveolar and jaw bones are developmentally derived from neural crest cells, while most trunk and limb bones are derived from mesodermal mesenchymal cells. Consequently, the chosen bone graft material is likely to have a different developmental origin than the recipient bone. We hypothesized that there are differences in the gene expression profiles and bone healing capacities between bones with different developmental origins. Therefore, we investigated these properties in the maxilla, mandible, ilium and femur. DNA microarray data revealed close homology between the gene expression profiles of the ilium and femur. The gene expressions of Wnt-1, P75, SOX10, Nestin and Musashi-1 were significantly higher in the maxilla and mandible than in the ilium and femur. The frontal bone healed faster than the parietal bone. Parietal bone defects transplanted with maxillary and mandibular bone grafts exhibited closure. Thus, it is suggested that the maxilla and mandible have different gene expression profiles from the other bones examined, and exhibit neural crest cell properties with a marked healing ability in adults. The data further suggest that jaw bones are effective as both bone graft materials and graft beds.
Project description:Previous investigations suggest that the different embryonic origins of the calvarial tissues (neural crest or mesoderm) may account for the different molecular mechanisms underlying sutural development. The aim of this study was to evaluate the differences in the gene expression of human cranial tissues and assess the presence of an expression signature reflecting their embryonic origins. Using microarray technology, we investigated global gene expression of cells from the frontal and parietal bones and the metopic and sagittal intrasutural mesenchyme (ISM) of four human fetal calvaria. Tissues samples were obtained from fetal crania of 4 normal human fetuses (two females ages 94 and 103 days and two males ages 97 and 98 days). All dural and extracranial soft tissues were removed from the parietal and frontal bones. 2-3 mm tissue compartments were excised from frontal and parietal bones and metopic and sagittal ISM. To avoid contamination with osteoblasts, ISM tissue was dissected from the central portion of each suture. Similarly, bone was harvested at least 3mm from the margin of the suture to avoid contamination with ISM. Media was changed every 3-4 days. After reaching 75-80% confluence, the cells were trypsinized with TrypLEExpress (Life Technologies, Denmark) and passaged. During the fourth and final passage, 180,000 cells were plated in triplicate in 6-well plates and cultured for 5 days followed by RNA extraction.
Project description:The mammalian skull vault consists mainly of 5 flat bones, the paired frontals and parietals, and the unpaired interparietal. All of these bones are formed by intramembranous ossification within a layer of mesenchyme, the skeletogenic membrane, located between the dermal mesenchyme and the meninges surrounding the brain. While the frontal bones are of neural crest in origin, the parietal bones arise from mesoderm. The present study is a characterization of frontal and parietal bones at their molecular level, aiming to highlight distinct differences between the neural crest-derived frontal and mesodermal-derived parietal bone. We performed a detailed comparative gene expression profile of FGF ligands and their receptors known to play crucial role in skeletogenesis. This analysis revealed that a differential expression pattern of the major FGF osteogenic molecules and their receptors exists between the neural crest-derived frontal bone and the paraxial mesoderm-derived parietal bone. Particularly, the expression of ligands such as Fgf-2, Fgf-9 and Fgf-18 was upregulated in frontal bone on embryonic day 17.5, postnatal day 1 and postnatal day 60 mice. Frontal bone also elaborated higher levels of Fgf receptor 1, 2 and 3 transcripts versus parietal bone. Taken together, these data suggest that the frontal bone is a domain with higher FGF-signaling competence than parietal bone.
Project description:Mesothelia, which cover all coelomic organs and body cavities in vertebrates, perform diverse functions in embryonic and adult life. Yet, mesothelia are traditionally viewed as simple, uniform epithelia. We used microarrays to demonstrate distinct differences between visceral and parietal mesothelia, the most basic subdivision of this tissue type, in terms of gene expression. Visceral mesothelium was isolated from the omentum of adult Wt1-cre;Rosa26ReYFP mice. In parallel, parietal mesothelium was isolated by teasing the mesothelium from the underlying skeletal muscle of the body wall of these animals. RNA was then extracted from these native mesothelia samples and used for hybridization in a microarray experiment.
Project description:Mesothelia, which cover all coelomic organs and body cavities in vertebrates, perform diverse functions in embryonic and adult life. Yet, mesothelia are traditionally viewed as simple, uniform epithelia. We used microarrays to demonstrate distinct differences between visceral and parietal mesothelia, the most basic subdivision of this tissue type, in terms of gene expression.
Project description:The gene expression profiles of murine visceral and parietal mesothelia were analyzed by microarray. Visceral and parietal mesothelia were isolated from the same adult Wt1-cre;Rosa26ReYFP reporter mice and analyzed. Whole tracscriptome expression analysis of total RNA was performed using Affymetrix mouse Gene 1.0 ST arrays.
Project description:Sutures separate the flat bones of the skull and enable coordinated growth of the brain and overlying cranium. In order to uncover the cellular diversity within sutures, we conducted single-cell transcriptomic and histological analyses of the embryonic murine coronal suture. We identify Erg and Pthlh as early markers of osteogenic progenitors in sutures, and distinct pre-osteoblast signatures between the bone fronts and periosteum. diverse mesenchymal layers at the coronal suture, including multiple distinct meningeal layers below the suture, and ligamentous, ectocranial, and hypodermal layers above the sutureIn the ectocranial layers above the suture, we observe a ligament-like population spanning the frontal and parietal bones and expressing genes implicated in mechanosensation. Mesenchyme in and around the coronal suture is asymmetrically distributed between the frontal and parietal bones, and we identify different states of osteogenic cells extending from the bone fronts into the more mature bone, and a potential signature for sutural stem cellsIn the meningeal layers, we detect a potential chondrogenic periosteal dura population that may be involved in endochondral ossification that closes sutures. Expression of genes mutated in craniosynostosis is spread across diverse cell types, suggesting multiple points at which homeostasis can fail. This single-cell atlas provides a resource to understand the development of the coronal suture, the suture most commonly fused in craniosynostosis.