Regulation of Cranial Suture Development by TGF-Beta and Fibroblast Growth Factor

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DESCRIPTION (provided by applicant): Craniosynostosis is a significant health issue in humans, yet the pathogenesis and the mechanism of craniosynostosis are still unsolved. Clinical and experimental studies have implicated Transforming Growth Factor-a 1 (TGF-beta1) and Fibroblast Growth Factor-2 in cranial suture fusion. There is evidence that the effect of one or both molecules on suture fusion may be further altered by noggin, a bone morphogenetic protein antagonist. Gain of function mutations in FGF receptors have been reported in numerous human craniosynostosis syndromes, with the majority of these syndromes implicating FGF receptors 2 (FGFR2). However, the precise role of TGF-beta1 and FGF-2 in cranial suture development has not been explained. We hypothesize that 1) during the period of posterior frontal (PF) suture development in the mouse, altered biologic activity of TGF-beta1 and FGF-2 regulates fusion of the overlying suture calvaria, and 2) expression of these molecules in the fused PF suture in mice parallels that in fused sutures from human children with congenital craniosynostosis. Alteration in FGFR2 and noggin may also contribute to alter biologic activity of TGF-Beta1 and FGF-2 and further regulate suture fusion. Specific aims are 1) To quantity gene expression of TGF-beta1, FGF-2, FGFR2, and noggin in mouse cranial tissues harvested from both in vivo and in vitro models. Additionally, protein levels of TGF- beta1, FDF-2, and noggin will be measured in culture media in vitro using ELISA. 2) To quantitate gene expression of these same growth factors and receptors harvested from human patients with cogenital craniosynostosis. We will harvest tissue from both a fused suture and a patent suture from children undergoing craniotomy as part of the standard treatment for craniosynotosis. These data will be used to help determine the relationship between the mouse and human cranial suture systems. 3) To modulate cranial suture fusion in the mouse model, in vitro by modulating the bioavailability of the growth factor and receptors described in Aim 1. We will add recombinant forms of each molecule or antibodies to these molecules to either induce fusion of the normally patent sagittal suture or block the normal fusion of the PF suture. 4) To investigate the possibility of in vitro plasmid DNA transfection of mouse cranial tissue. If successful, gene manipulation of the target growth factors and receptors may be used to regulate cranial suture development in future studies. 5) To gain adequate knowledge of molecular biology to develop into an independent clinician-scientist. This proposal will provide mechanistic insights into the regulation of cranial suture development, and help to relate mouse and human models of craniosynostosis.