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Craniosynostosis is characterized by premature fusion of the cranial sutures. At the molecular level, mutations in homeobox genes, transcription factors, and growth factor receptors have been implicated in the pathogenesis of this disorder, but the specific etiologic pathways have not yet been elucidated. To further study the molecular biology behind craniosynostosis, perisutural tissues in a unique rabbit model with congenital delayed-onset coronal craniosynostosis were examined for the presence of the hedgehog family of growth factors and their receptor, patched-1. Expression of desert hedgehog, Indian hedgehog, sonic hedgehog, and patched-1 was evaluated in four areas: suture, endosteum, periosteum, and osteocytes, using immuno-histochemistry (n = 8). Protein levels in affected animals were compared with protein levels in wild-type control rabbits (n = 8). Overall, sonic hedgehog, Indian hedgehog, and patched-1 protein levels were greater in affected animals. Specifically, areas of increased staining were seen along the bony interface of the endosteum and periosteum and in the osteocytes of the synostotic rabbits. Interestingly, in the suture, increased levels of Indian hedgehog and sonic hedgehog, but not patched-1, were seen. There was minimal expression of desert hedgehog in both rabbit types. The increased overall presence of hedgehog and patched-1 proteins in synostotic rabbits may be a reactive change to the disorder or part of the pathogenic process. Although the specific cause cannot be determined from the data, it is clear that the molecular milieu of the cranial sutures in synostotic rabbits is markedly different from that of wild-type rabbits.

With the modern emphasis on minimally invasive therapies, the concept of distraction is being applied in the treatment of craniosynostosis. Although specific genetic mutations have been identified in craniosynostotic patients, changes in the gene expression induced by cranial distraction have not yet been explored. The effects of cranial distraction on hedgehog and patched-1 expression were evaluated in a rabbit model for craniosynostosis. Rabbits (n = 8) were divided into four groups: affected rabbits, wild-type rabbits, affected rabbits subject to cranial distraction, and wild-type rabbits subject to distraction. Perisutural tissue was examined using immunohistochemistry in four areas: suture, endosteum, periosteum, and osteocytes, for the expression of Indian hedgehog, sonic hedgehog, and desert hedgehog and their receptor, patched-1. Two experimental groups were compared: (1) wild-type before distraction to wild-type after distraction, and (2) synostotic before distraction to synostotic after distraction. Distraction produced several variable and interesting changes in hedgehog protein presence. In wild-type rabbits, the predominant effect was a mild decrease in Indian hedgehog levels. Sonic and desert hedgehog and patched-1 protein levels were unchanged. In synostotic rabbits, the predominant effect of distraction was to decrease Indian hedgehog, sonic hedgehog, and patched-1 protein levels. This was especially true in the periosteum and endosteum. Cranial distraction of normal and affected rabbits differentially changed both the expression levels and patterns of the hedgehog and patched-1 proteins in the cranial tissues examined. These results suggest that molecular and genetic parameters of distraction and bone response may be different in craniosynostotic individuals, which may influence treatment protocols in these patients.

The organization of the basolateral membrane domain of highly polarized intestinal absorptive cells was studied in adult rat intestinal mucosa, during development of polarity in fetal intestine, and in isolated epithelial sheets. Semi-thin frozen sections of these tissues were stained with a monoclonal antibody (mAb 4C4) directed against Na+,K+-ATPase, and with other reagents to visualize distributions of the membrane skeleton (fodrin), an epithelial cell adhesion molecule (uvomorulin), an apical membrane enzyme (aminopeptidase), and filamentous actin. In intact adult epithelium, Na+,K+-ATPase, membrane-associated fodrin, and uvomorulin were concentrated in the lateral, but not basal, subdomain. In the stratified epithelium of fetal intestine, both fodrin and uvomorulin were localized in areas of cell-cell contact at 16 and 17 d gestation, a stage when Na+,K+-ATPase was not yet expressed. These molecules were excluded from apical domains and from cell surfaces in contact with basal lamina. When Na+,K+-ATPase appeared at 18-19 d, it was codistributed with fodrin. Detachment of epithelial sheets from adult intestinal mucosa did not disrupt intercellular junctions or lateral cell contacts, but cytoplasmic blebs appeared at basal cell surfaces, and a diffuse pool of fodrin and actin accumulated in them. At the same time, Na+,K+-ATPase moved into the basal membrane subdomain, and extensive endocytosis of basolateral membrane, including Na+,K+-ATPase, occurred. Endocytosis of uvomorulin was not detected and no fodrin was associated with endocytic vesicles. Uvomorulin, along with some membrane-associated fodrin and some Na+,K+-ATPase, remained in the lateral membrane as long as intercellular contacts were maintained. Thus, in this polarized epithelium, interaction of lateral cell-cell adhesion molecules as well as basal cell-substrate interactions are required for maintaining the stability of the lateral membrane skeleton and the position of resident membrane proteins concentrated in the lateral membrane domain.