IGFs increase enamel formation by inducing expression of enamel mineralizing specific genes.
Insulin-like growth factors (IGF-I and IGF-II) have been shown to play an important role in growth and differentiation in a number of tissues including mineralizing bone. Little is known about their role in tooth mineralization. Previous work in our laboratory has shown the presence of IGFs ligands, their receptors, and their binding proteins during mouse tooth morphogenesis. The expression of IGF I coincides with the expression of amelogenin, ameloblastin and enamelin at the late bell and secretory stage. The objective of this study is to determine the mechanisms by which IGFs modulate enamel and dentin formation. Mouse first mandibular molars were dissected from E16 and E17 mouse embryos and placed in organ culture in the presence of IGF-I or IGF-II. The molars were harvested after 12 days for histological examination or 1 day for mRNA expression analysis by real-time RT-PCR. Our results show an increase in enamel deposition, and an induction of enamelin, amelogenin and collagen type I mRNA expression, while expression of DSPP was down-regulated. These results suggest that IGFs increase enamel formation by the induction of gene expression of enamel related genes. Studies are underway to determine a possible mechanism for these factors.
Catón
Javier
J
Center for Craniofacial Molecular Biology, University of Southern California School of Dentistry, 2250 Alcazar St., CSA 106, Los Angeles, CA 90033, USA.
Bringas
Pablo
P
Zeichner-David
Margarita
M
D053523:Amelogenin; D000818:Animals; D024042:Collagen Type I / Q000235:genetics; D003743:Dental Enamel / Q000196:embryology* / Q000378:metabolism; D003746:Dental Enamel Proteins / Q000235:genetics; D003810:Dentinogenesis / Q000235:genetics*; D016326:Extracellular Matrix Proteins; D005786:Gene Expression Regulation / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D008963:Molar; D009924:Organ Culture Techniques; D010750:Phosphoproteins; D011498:Protein Precursors / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012795:Sialoglycoproteins; D013002:Somatomedins / Q000378:metabolism* / Q000494:pharmacology; D000099311:Dentin Sialophosphoprotein
D053523:Amelogenin; D024042:Collagen Type I; D003746:Dental Enamel Proteins; D016326:Extracellular Matrix Proteins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D010750:Phosphoproteins; D011498:Protein Precursors; D012333:RNA, Messenger; D012795:Sialoglycoproteins; D013002:Somatomedins; D000099311:Dentin Sialophosphoprotein; C507200:Amelx protein, mouse; C038456:tuftelin