title: Requirements for ion and solute transport, and pH regulation during enamel maturation.
abstract: Transcellular bicarbonate transport is suspected to be an important pathway used by ameloblasts to regulate extracellular pH and support crystal growth during enamel maturation. Proteins that play a role in amelogenesis include members of the ABC transporters (SLC gene family and CFTR). A number of carbonic anhydrases (CAs) have also been identified. The defined functions of these genes are likely interlinked during enamel mineralization. The purpose of this study is to quantify relative mRNA levels of individual SLC, Cftr, and CAs in enamel cells obtained from secretory and maturation stages on rat incisors. We also present novel data on the enamel phenotypes for two animal models, a mutant porcine (CFTR-ΔF508) and the NBCe1-null mouse. Our data show that two SLCs (AE2 and NBCe1), Cftr, and Car2, Car3, Car6, and Car12 are all significantly up-regulated at the onset of the maturation stage of amelogenesis when compared to the secretory stage. The remaining SLCs and CA gene transcripts showed negligible expression or no significant change in expression from secretory to maturation stages. The enamel of CFTR-ΔF508 adult pigs was hypomineralized and showed abnormal crystal growth. NBCe1-null mice enamel was structurally defective and had a marked decrease in mineral content relative to wild-type. These data demonstrate the importance of many non-matrix proteins to amelogenesis and that the expression levels of multiple genes regulating extracellular pH are modulated during enamel maturation in response to an increased need for pH buffering during hydroxyapatite crystal growth.
authors: Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California 90033, USA. rodrigo@usc.edu
authors: Rodrigo S
authors: RS
authors: Lacruz
authors: Charles E
authors: CE
authors: Smith
authors: Pierre
authors: P
authors: Moffatt
authors: Eugene H
authors: EH
authors: Chang
authors: Timothy G
authors: TG
authors: Bromage
authors: Pablo
authors: P
authors: Bringas
authors: Antonio
authors: A
authors: Nanci
authors: Sanjeev K
authors: SK
authors: Baniwal
authors: Joseph
authors: J
authors: Zabner
authors: Michael J
authors: MJ
authors: Welsh
authors: Ira
authors: I
authors: Kurtz
authors: Michael L
authors: ML
authors: Paine
mesh_terms: D000566:Amelogenesis / Q000235:genetics / Q000502:physiology; D000818:Animals; D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism; D017920:Antiporters / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D003743:Dental Enamel / Q000002:abnormalities / Q000254:growth & development* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008855:Microscopy, Electron, Scanning; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D064606:SLC4A Proteins; D027982:Sodium-Bicarbonate Symporters / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000235:genetics; D034421:Sus scrofa
chemical_list: D027321:Anion Transport Proteins; D017920:Antiporters; D017931:DNA Primers; D050505:Mutant Proteins; C499849:NCX1 protein, mouse; D012333:RNA, Messenger; D064606:SLC4A Proteins; C498899:Slc4a4 protein, mouse; C491101:Slc8a3 protein, mouse; D027982:Sodium-Bicarbonate Symporters; D019831:Sodium-Calcium Exchanger; D019005:Cystic Fibrosis Transmembrane Conductance Regulator