title: Human osteoblastic cells discriminate between 20-kDa amelogenin isoforms.
abstract: Enamel matrix derivative (EMD) is used to stimulate healing of alveolar bone after destructive marginal periodontitis; however, the roles of the different EMD constituents are unclear. The aim here was to compare the effect of two EMD fractions (A1 and A2) on primary human osteoblasts cultured in the presence of 50 μg ml(-1) of A1, A2, or EMD. SDS-PAGE showed that A1 and A2 were comprised of amelogenins migrating at around 20 kDa. Fourier transform infrared (FTIR) analysis revealed that A1 and A2 had different secondary structures, and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) identified different peptide mass values. Osteoblasts responded differently to A1 and A2. Whereas A1 enhanced the proliferation [measured by the incorporation of 5-bromo-2'-deoxyuridine (BrdU)] of osteoblasts, the expression of runt-related transcription factor-2 (RUNX2) mRNA, and the secretion of interleukin 6 (IL-6) into the cell culture medium, exposure to A2 resulted in increased alkaline phosphatase (ALP) activity, increased expression of CD44 mRNA, and increased secretion of osteoprotegrin (OPG) and receptor activator of nuclear factor-kappaB ligand (RANKL). The level of osteocalcin in the cell culture medium was increased after all treatments, while A2 stimulated the expression of dentin matrix protein 1 (DMP1) mRNA. The results suggest that both A1 and A2 participate in the observed effect of EMD, but have different effects on the expression of osteoblast mRNA and the secretion of osteoblast protein, and thus might facilitate the differentiation of a different phenotype.
authors.affiliation: Department of Biomaterials, Faculty of Dentistry, University of Oslo, Oslo, Norway.
authors.forename: Elisabeth A
authors.initials: EA
authors.lastname: Riksen
authors.forename: Christiane
authors.initials: C
authors.lastname: Petzold
authors.forename: Steven
authors.initials: S
authors.lastname: Brookes
authors.forename: Ståle P
authors.initials: SP
authors.lastname: Lyngstadaas
authors.forename: Janne E
authors.initials: JE
authors.lastname: Reseland
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D053523:Amelogenin / Q000737:chemistry*; D000704:Analysis of Variance; D049109:Cell Proliferation; D002478:Cells, Cultured; D050659:Core Binding Factor Alpha 1 Subunit / Q000096:biosynthesis / Q000235:genetics; D003470:Culture Media / Q000737:chemistry; D003746:Dental Enamel Proteins / Q000737:chemistry; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis; D006801:Humans; D018960:Hyaluronan Receptors / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis; D008970:Molecular Weight; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D015675:Osteocalcin / Q000096:biosynthesis; D053244:Osteoprotegerin / Q000096:biosynthesis; D010750:Phosphoproteins / Q000096:biosynthesis; D020033:Protein Isoforms; D017433:Protein Structure, Secondary; D053245:RANK Ligand / Q000096:biosynthesis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D053523:Amelogenin; D050659:Core Binding Factor Alpha 1 Subunit; D003470:Culture Media; C513309:DMP1 protein, human; D003746:Dental Enamel Proteins; D016326:Extracellular Matrix Proteins; D018960:Hyaluronan Receptors; D015850:Interleukin-6; D053244:Osteoprotegerin; D010750:Phosphoproteins; D020033:Protein Isoforms; D053245:RANK Ligand; C109069:enamel matrix proteins; D015675:Osteocalcin; D000469:Alkaline Phosphatase