Enhanced activity of osteoblast differentiation factor (PEBP2alphaA2/CBFa1) in affected sutural osteoblasts from patients with nonsyndromic craniosynostosis.
OBJECTIVE
Nonsyndromic craniosynostosis is characterized by premature closure of one or more cranial sutures in infants. The purpose of this investigation was to evaluate cellular and molecular events that lead to pathogenesis of nonsyndromic craniosynostosis.


METHODS
This study utilized discarded samples of normal and affected cranial sutures from 12 patients (7 boys, 5 girls) with nonsyndromic craniosynostosis.


RESULTS
Histological evaluation of affected sutures revealed complete osseous obliteration instead of a zone of connective tissue and osteogenic cells as seen in normal sutures. Although proliferation of normal and affected osteoblasts did not vary substantially, elevated osteocalcin production and increased in vitro bone nodule formation indicated that the differentiation and the bone-forming potential of affected osteoblasts was significantly higher than that of normal cells. We therefore investigated the levels and activity of Cbfa1, a transcription factor that plays an integral role in osteoblast differentiation. Northern blot analysis of messenger RNA from both normal and affected sutural osteoblasts revealed a twofold increase in the expression of Cbfa1 in affected cells. This increase in the level of Cbfa1 transcript correlated with an increase in its transcriptional activity on the osteocalcin gene promoter, as assessed using gene transfer methods.


CONCLUSIONS
Our results indicated that osteoblasts from synostosed sutures exhibit an increased potential for differentiation and bone formation. The increased level and activity of Cbfa1 could play a vital role in the aberrant function of these affected osteoblasts and may explain their altered behavior compared to the normal cells.
Shevde
N K
NK
Department of Biochemistry, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA. shevde@biochem.wisc.edu
Bendixen
A C
AC
Maruyama
M
M
Li
B L
BL
Billmire
D A
DA
D000469:Alkaline Phosphatase; D000704:Analysis of Variance; D015152:Blotting, Northern; D002113:Calcification, Physiologic; D018929:Cell Culture Techniques; D002454:Cell Differentiation; D002455:Cell Division; D004396:Coloring Agents; D003238:Connective Tissue / Q000473:pathology; D050659:Core Binding Factor Alpha 1 Subunit; D003393:Cranial Sutures / Q000378:metabolism / Q000473:pathology*; D003398:Craniosynostoses / Q000378:metabolism / Q000473:pathology*; D004268:DNA-Binding Proteins / Q000032:analysis* / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007223:Infant; D008297:Male; D009363:Neoplasm Proteins; D010006:Osteoblasts / Q000378:metabolism / Q000473:pathology*; D015675:Osteocalcin / Q000032:analysis; D010012:Osteogenesis; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D013223:Statistics as Topic; D014157:Transcription Factors / Q000032:analysis* / Q000235:genetics; D014158:Transcription, Genetic; D014162:Transfection
D004396:Coloring Agents; D050659:Core Binding Factor Alpha 1 Subunit; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D015675:Osteocalcin; D000469:Alkaline Phosphatase