Bone Abstracts

Background: Skull development is a tightly regulated process that occurs along the osteogenic interfaces of the cranial sutures that allow rapid bone formation at the edges of the bone fronts. Premature closure of cranial sutures can result in pathological conditions such as Craniosynostosis. The mechanosensory proteins Polycystin 1 (PC1) and 2 (PC2) have been shown to regulate skeletal development and potentially suture formation.

Aim: The aim of study was to investigate the implication of PC1/PC2 in suture development and suture fusion.

Methods: Presence of PC1 and PC2 proteins was investigated in rat sagittal (SAG) sutures tissue sections during postnatal development at p1/p5/p15 days of Sprague Dawley rats. PC1/PC2 localization and expression levels were investigated in primary suture SAG cell populations and human craniosynostosis tissue samples by RT-PCR, PCR, Western Immunoblotting and Immunohistochemistry. Ethical approval was obtained for all experimental protocols.

Results: Western Immunoblotting revealed a differential expression pattern for PC1 and PC2 in SAG sutures at p1/p5/p15 days. PC1/PC2 levels were elevated at postnatal day 5. Immunohistochemical analysis showed nuclear localization of PC1/PC2 expression in fused sutures. In primary suture SAG cell cultures, PC1 and PC2 presence was associated with an elevated expression of the osteoblast marker RUNX2 and a lower expression of chondrocyte marker SOX-9. PC1 and PC2 expression in human craniosynostosis samples was detected in the area of synostotic sutures.

Conclusion: Polycystins are implicated in suture formation and growth, playing a potential role in premature obliteration of sutures that occur in pathological conditions such as Craniosynostosis. Further research is required to elucidate PC-induced molecular pathways in suture fusion processes for detection of specific molecular targets to complement current therapy and diagnostic schemes.