Role of annexin 1 gene expression in mouse craniofacial bone development.
BACKGROUND
Annexin 1 is a 37-kDa protein that has complex intra- and extracellular effects. To discover whether the absence of this protein alters bone development, we monitored this event in the annexin-A1 null mice in comparison with littermate wild-type controls.


METHODS
Radiographic and densitometry methods were used for the assessment of bone in annexin-A1 null mice at a gross level. We used whole-skeleton staining, histological analysis, and Western blotting techniques to monitor changes at the tissue and cellular levels.


RESULTS
There were no gross differences in the appendicular skeleton between the genotypes, but an anomalous development of the skull was observed in the annexin-A1 null mice. This was characterized in the newborn annexin-A1 null animals by a delayed intramembranous ossification of the skull, incomplete fusion of the interfrontal suture and palatine bone, and the presence of an abnormal suture structure. The annexin-A1 gene was shown to be active in osteocytes during this phase and COX-2 was abundantly expressed in cartilage and bone taken from annexin-A1 null mice.


CONCLUSIONS
Expression of the annexin-A1 gene is important for the normal development of the skull in mice, possibly through the regulation of osteoblast differentiation and a secondary effect on the expression of components of the cPLA2-COX-2 system.
Damazo
Amilcar Sabino
AS
Post-Graduation in Morphology, Federal University of São Paulo (UNIFESP)-Paulista School of Medicine (EPM), São Paulo, Brazil.
Moradi-Bidhendi
Niloufar
N
Oliani
Sonia Maria
SM
Flower
Roderick John
RJ
D000818:Animals; D000831:Animals, Newborn; D017305:Annexin A1 / Q000235:genetics*; D015519:Bone Density; D001846:Bone Development / Q000235:genetics; D001842:Bone and Bones / Q000002:abnormalities*; D019465:Craniofacial Abnormalities / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D051546:Cyclooxygenase 2 / Q000378:metabolism; D005260:Female; D015870:Gene Expression / Q000502:physiology*; D006720:Homozygote; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010012:Osteogenesis; D010741:Phospholipases A / Q000378:metabolism
D017305:Annexin A1; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D010741:Phospholipases A