Fluoride does not inhibit enamel protease activity.
Fluorosed enamel can be porous, mottled, discolored, hypomineralized, and protein-rich if the enamel matrix is not completely removed. Proteolytic processing by matrix metalloproteinase-20 (MMP20) and kallikrein-4 (KLK4) is critical for enamel formation, and homozygous mutation of either protease results in hypomineralized, protein-rich enamel. Herein, we demonstrate that the lysosomal proteinase cathepsin K is expressed in the enamel organ in a developmentally defined manner that suggests a role for cathepsin K in degrading re-absorbed enamel matrix proteins. We therefore asked if fluoride directly inhibits the activity of MMP20, KLK4, dipeptidyl peptidase I (DPPI) (an in vitro activator of KLK4), or cathepsin K. Enzyme kinetics were studied with quenched fluorescent peptides with purified enzyme in the presence of 0-10 mM NaF, and data were fit to Michaelis-Menten curves. Increasing concentrations of known inhibitors showed decreases in enzyme activity. However, concentrations of up to 10 mM NaF had no effect on KLK4, MMP20, DPPI, or cathepsin K activity. Our results show that fluoride does not directly inhibit enamel proteolytic activity.
Department of Cytokine Biology, The Forsyth Institute, Harvard School of Dental Medicine, Boston, MA 02115, USA.
C E
CE
Tye
J V
JV
Antone
J D
JD
Bartlett
D000565:Ameloblasts / Q000187:drug effects; D000566:Amelogenesis / Q000187:drug effects / Q000502:physiology; D000818:Animals; D020789:Cathepsin C / Q000032:analysis / Q000187:drug effects; D056657:Cathepsin K / Q000037:antagonists & inhibitors / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003743:Dental Enamel / Q000201:enzymology*; D003746:Dental Enamel Proteins / Q000187:drug effects*; D004151:Dipeptides / Q000008:administration & dosage / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004658:Enamel Organ / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005459:Fluorides / Q000494:pharmacology*; D007610:Kallikreins / Q000037:antagonists & inhibitors / Q000187:drug effects; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D053519:Matrix Metalloproteinase 20 / Q000187:drug effects; D061965:Matrix Metalloproteinase Inhibitors; D010447:Peptide Hydrolases / Q000187:drug effects*; D011480:Protease Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D015842:Serine Proteinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology; D013450:Sulfones / Q000008:administration & dosage / Q000494:pharmacology; D013552:Swine; D013997:Time Factors
D015853:Cysteine Proteinase Inhibitors; D003746:Dental Enamel Proteins; D004151:Dipeptides; D004791:Enzyme Inhibitors; D061965:Matrix Metalloproteinase Inhibitors; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D011480:Protease Inhibitors; D015842:Serine Proteinase Inhibitors; D013450:Sulfones; C002010:4-(2-aminoethyl)benzenesulfonylfluoride; D010447:Peptide Hydrolases; D020789:Cathepsin C; D007610:Kallikreins; C120801:kallikrein 4; D056657:Cathepsin K; D053519:Matrix Metalloproteinase 20; D007930:Leucine; D005459:Fluorides; C024974:E 64