Amelogenin in cranio-facial development: the tooth as a model to study the role of amelogenin during embryogenesis.
The amelogenins comprise 90% of the developing extracellular enamel matrix proteins and play a major role in the biomineralization and structural organization of enamel. Amelogenins were also detected, in smaller amounts, in postnatal calcifying mesenchymal tissues, and in several nonmineralizing tissues including brain. Low molecular mass amelogenin isoforms were suggested to have signaling activity; to produce ectopically chondrogenic and osteogenic-like tissue and to affect mouse tooth germ differentiation in vitro. Recently, some amelogenin isoforms were found to bind to the cell surface receptors; LAMP-1, LAMP-2 and CD63, and subsequently localize to the perinuclear region of the cell. The recombinant amelogenin protein (rHAM(+)) alone brought about regeneration of the tooth supporting tissues: cementum, periodontal ligament and alveolar bone, in the dog model, through recruitment of progenitor cells and mesenchymal stem cells. We show that amelogenin is expressed in various tissues of the developing mouse embryonic cranio-facial complex such as brain, eye, ganglia, peripheral nerve trunks, cartilage and bone, and is already expressed at E10.5 in the brain and eye, long before the initiation of tooth formation. Amelogenin protein expression was detected in the tooth germ (dental lamina) already at E13.5, much earlier than previously reported (E19). Application of amelogenin (rHAM(+)) beads together with DiI, on E13.5 and E14.5 embryonic mandibular mesenchyme and on embryonic tooth germ, revealed recruitment of mesenchymal cells. The present results indicate that amelogenin has an important role in many tissues of the cranio-facial complex during mouse embryonic development and differentiation, and might be a multifunctional protein.
Gruenbaum-Cohen
Yael
Y
Dental Research Laboratory, Institute of Dental Sciences, Hebrew University, Hadassah, Faculty of Dental Medicine, Jerusalem, Israel.
Tucker
Abigail S
AS
Haze
Amir
A
Shilo
Dekel
D
Taylor
Angela L
AL
Shay
Boaz
B
Sharpe
Paul T
PT
Mitsiadis
Thimios A
TA
Ornoy
Asher
A
Blumenfeld
Anat
A
Deutsch
Dan
D
D000567:Amelogenesis Imperfecta / Q000235:genetics; D053523:Amelogenin / Q000235:genetics*; D000818:Animals; D001846:Bone Development; D001842:Bone and Bones / Q000196:embryology; D002356:Cartilage / Q000196:embryology / Q000254:growth & development; D003746:Dental Enamel Proteins / Q000502:physiology; D005091:Exons; D016326:Extracellular Matrix Proteins / Q000502:physiology*; D005724:Ganglia / Q000196:embryology / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D051379:Mice; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014070:Tooth / Q000196:embryology / Q000254:growth & development*
D053523:Amelogenin; D003746:Dental Enamel Proteins; D016326:Extracellular Matrix Proteins; D012333:RNA, Messenger; C109069:enamel matrix proteins