Expression of Runx2/Cbfa1/Pebp2alphaA during angiogenesis in postnatal rodent and fetal human orofacial tissues.
Transient expression of Runx2 is reported in endothelial cells and vascular smooth muscle cells during vessel formation in skin, stroma of forming bones and developing periodontal ligament, developing skeletal muscle cells, and fat tissue. The data suggest that Runx2 is expressed in a multipotential mesenchymal cell population that gives rise to various osseous and nonosseous cell lineages.


BACKGROUND
Runx2/Cbfa1 is a transcription factor essential for cells of osteogenic and dentinogenic lineages. Here we examined expression of Runx2/Cbfa1 (all isotypes) in several nonskeletal cell types present in developing orofacial tissues of neonatal rodents and human fetuses with special emphasis on vessel formation.


METHODS
Sections obtained from heads or jaws of postnatal mice, hamster, and human fetuses were immunostained with monoclonal anti-Pebp2aA antibody. Mouse and human tissues were also examined by in situ hybridization. Sections of Runx2 null mutant mice with a LacZ reporter construct inserted in the Runx2 locus were stained for Runx2 promoter activity with anti-galactosidase.


RESULTS
We found transient mRNA and protein expression in endothelial cells and in vascular smooth muscle cells of forming vessels in skin, alveoli of forming bone, and forming periodontal ligament. We also noticed weak and variable expression in some fibroblasts of embryonic skin, early differentiating cross-striated muscle cells, and differentiating fat cells.


CONCLUSIONS
Runx2 is not an exclusive marker for chondrogenic, osteogenic, and dentinogenic tissues, but is much more widely present in an early multipotential mesenchymal cell population that gives rise to several other lineages.
Bronckers
Antonius L J J
AL
Department of Oral Cell Biology, ACTA, Vrije Universiteit and Universiteit van Amsterdam, Amsterdam, The Netherlands. A.Bronckers@vumc.nl
Sasaguri
Kenichi
K
Cavender
Adriana C
AC
D'Souza
Rena N
RN
Engelse
Marten A
MA
D000818:Animals; D050659:Core Binding Factor Alpha 1 Subunit; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics; D005333:Fetus / Q000166:cytology / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D006801:Humans; D007568:Jaw / Q000098:blood supply* / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D018919:Neovascularization, Physiologic / Q000502:physiology*; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics
D050659:Core Binding Factor Alpha 1 Subunit; D004268:DNA-Binding Proteins; C493709:RUNX2 protein, human; C493716:Runx2 protein, mouse; D050656:Transcription Factor AP-2; D014157:Transcription Factors