Identification of differentially expressed proteins between fused and open sutures in sagittal nonsyndromic craniosynostosis during suture development by quantitative proteomic analysis

Abstract

Purpose: Nonsyndromic craniosynostosis (NCS), the premature fusion of cranial sutures, results in an abnormal skull shape and is associated with a significant morbidity. Proteomics is a promising tool for disease characterization and biomarker discovery; we aimed to identify biologically relevant differentially expressed proteins for NCS. Experimental design: Label-based quantitative proteomic profiling using TMT was performed on protein extracted from mesenchymal stem cells, osteoblasts and bone tissue of five open and five fused sutures of sagittal NCS (sNCS) and analyzed using quantitative LC-MS/MS based bottom-up proteomics. Differential protein abundance between open and fused sutures was determined to identify biologically relevant proteins of interest. Proteins were validated in an independent sample set by western blot and immunohistochemistry. Results: We observed 838 differentially expressed proteins between open and fused sutures of sNCS. Decorin, lumican, and asporin were significantly downregulated while COL4A1 and TGFβ1|1 were upregulated in fused compared to open sutures. Conclusions and clinical relevance: The majority of significantly differentially expressed proteins between open and fused sutures were observed in the proteomes of osteoblasts suggesting that protein changes contributing to premature sagittal suture fusion occur predominantly at the osteoblast level. Our findings suggest a possible ineffective ECM deposition at the osteoblast cell stage.