Semaphorin 4D inhibits collagen synthesis of rat pulp-derived cells.
OBJECTIVE
Semaphorins are a group of secreted and membrane-associated molecules that play important roles in axon navigation. Several semaphorin family molecules are expressed in the pharyngeal arches and tooth germs. We analysed the expression of membrane-associated Semaphorin 4D (Sema4D) in tooth germs, and examined its potential role in regulating the differentiation of rat incisor pulp-derived cells in vitro.


METHODS
mRNA expression was examined by in situ hybridisation. The effects of Sema4D on rat pulp-derived cells were examined by adenovirus-mediated overexpression in vitro.


RESULTS
Both epithelial and mesenchymal cells of tooth germs expressed Sema4D at the early bell stage. Later, the odontoblasts predominantly expressed Sema4D, while the epithelial expression greatly decreased. The overexpression of Sema4D in rat incisor pulp-derived cells strongly inhibited mineralisation. This inhibition was preceded by a reduction of collagen fibre production at the level of mRNA synthesis.


CONCLUSIONS
These results indicate that Sema4D is expressed in both epithelial and mesenchymal cells of the tooth germs. Sema4D represses collagen synthesis of pulp-derived cells, indicating it might negatively regulate odontoblast differentiation.
Abe
Makoto
M
Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, Osaka 565-0871, Japan. m-abe@dent.osaka-u.ac.jp
Inagaki
Shinobu
S
Furuyama
Tatsuo
T
Iwamoto
Masahiro
M
Wakisaka
Satoshi
S
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D002478:Cells, Cultured; D003094:Collagen / Q000032:analysis / Q000096:biosynthesis*; D003782:Dental Pulp / Q000187:drug effects / Q000378:metabolism*; D003864:Depression, Chemical; D020690:GTPase-Activating Proteins / Q000235:genetics; D015870:Gene Expression; D005822:Genetic Vectors / Q000008:administration & dosage; D015151:Immunoblotting / Q000379:methods; D007180:Incisor; D007763:Lac Operon; D051379:Mice; D008813:Mice, Inbred ICR; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011956:Receptors, Cell Surface / Q000235:genetics; D039961:Semaphorins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D014089:Tooth Remineralization; D014161:Transduction, Genetic / Q000379:methods
D015703:Antigens, CD; C093224:CD100 antigen; D020690:GTPase-Activating Proteins; C488752:Plxnb1 protein, rat; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D039961:Semaphorins; D003094:Collagen