Decreased mineral content in MMP-20 null mouse enamel is prominent during the maturation stage.
During enamel development, matrix metalloproteinase-20 (MMP-20, enamelysin) is expressed early during the secretory stage as the enamel thickens, and kallikrein-4 (KLK-4, EMSP1) is expressed later during the maturation stage as the enamel hardens. Thus, we investigated whether the physical properties of the secretory-/maturation-stage MMP-20 null enamel were significantly different from those of controls. We demonstrated that although, in relative terms, the weight percent of mature mineral in the MMP-20 null mouse enamel was only 7-16% less than that in controls, overall the enamel mineral was reduced by about 50%, and its hardness was decreased by 37%. Percent mineral content by weight was assessed at 3 different developmental stages. Remarkably, the biggest difference in mineral content between MMP-20 null and controls occurred in the nearly mature enamel, when MMP-20 is normally no longer expressed. This suggests that MMP-20 acts either directly or indirectly to facilitate the removal of maturation-stage enamel proteins.
Bartlett
J D
JD
Department of Cytokine Biology, The Forsyth Institute, 140 The Fenway, Boston, MA 02115, USA. jbartlett@forsyth.org
Beniash
E
E
Lee
D H
DH
Smith
C E
CE
D000566:Amelogenesis / Q000235:genetics*; D000818:Animals; D003743:Dental Enamel / Q000737:chemistry*; D003746:Dental Enamel Proteins / Q000032:analysis; D006244:Hardness; D007610:Kallikreins / Q000235:genetics; D053519:Matrix Metalloproteinase 20; D020782:Matrix Metalloproteinases / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008903:Minerals / Q000032:analysis*; D010710:Phosphates / Q000032:analysis; D017550:Spectroscopy, Fourier Transform Infrared
D003746:Dental Enamel Proteins; D008903:Minerals; D010710:Phosphates; D007610:Kallikreins; C120801:kallikrein 4; D053519:Matrix Metalloproteinase 20; D020782:Matrix Metalloproteinases; C507113:Mmp20 protein, mouse