Enamelysin and kallikrein-4 mRNA expression in developing mouse molars.
Proteolytic processing and degradation of enamel matrix proteins appears to be an essential feature of dental enamel formation. The source and character of proteolytic activity in the enamel matrix of developing teeth changes as enamel formation progresses. Two proteinases have been isolated from the extracellular enamel matrix of developing teeth: enamelysin (MMP-20), a matrix metalloproteinase. and kallikrein-4 (KLK4), a serine proteinase. Here, we ask if the expression of MMP-20 and KLK4 correlate with the stage-associated changes in the digestion of enamel proteins. Using in situ hybridization, we localized MMP-20 and KLK4 mRNA in mouse maxillary first molars on postnatal days 1, 2, 3, 5, 6, 7, 9, 11, and 14. Enamelysin signal was first detected in preameloblasts, ameloblasts, and odontoblasts on day 2, but not in ameloblasts covering the enamel-free zone. Enamelysin signal declined in ameloblasts on day 6 but persisted in the dental pulp. In contrast, KLK4 transcripts were first observed on day 3 in pulp and on day 6 in ameloblasts covering the enamel-free zone. the KLK4 signal was present in maturation-stage ameloblasts on days 9, 11, and 14. The expression patterns of MMP-20 and KLK4 by ameloblasts in mouse molars are stage-specific and complementary.
Hu
Jan C C
JC
University of Texas School of Dentistry, Health Science Center at San Antonio, Department of Pediatric Dentistry, 78229-3900, USA.
Sun
Xiaoling
X
Zhang
Chuhua
C
Liu
Shengxi
S
Bartlett
John D
JD
Simmer
James P
JP
D000566:Amelogenesis / Q000502:physiology*; D000818:Animals; D001345:Autoradiography; D003743:Dental Enamel / Q000201:enzymology*; D003746:Dental Enamel Proteins / Q000096:biosynthesis*; D003782:Dental Pulp / Q000201:enzymology; D004658:Enamel Organ / Q000201:enzymology*; D005109:Extracellular Matrix / Q000201:enzymology; D017403:In Situ Hybridization; D007610:Kallikreins / Q000096:biosynthesis*; D053519:Matrix Metalloproteinase 20; D020782:Matrix Metalloproteinases / Q000096:biosynthesis*; D051379:Mice; D008963:Molar / Q000201:enzymology; D015347:RNA Probes; D012333:RNA, Messenger / Q000096:biosynthesis
D003746:Dental Enamel Proteins; D015347:RNA Probes; D012333:RNA, Messenger; D007610:Kallikreins; C120801:kallikrein 4; D053519:Matrix Metalloproteinase 20; D020782:Matrix Metalloproteinases; C507113:Mmp20 protein, mouse