Abstract
Tooth germ development is associated with morphological and biochemical changes of the dental papilla and enamel organ. Enzymes with gelatinolytic activities were studied by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and enzymography in tooth germ of newborn to 15-day-old rats. Three major bands with gelatinolytic activity were detected at all periods and characterized as the latent and active forms of MMP-2 using their molecular weight and activity dependent on Zn++ and Ca++ ions as criteria. Expression and activity of MMP-2 increased progressively from 0 to 15 days after birth. Mechanical separation of the tooth germ from 10-day-old rats showed that the gelatinolytic activity was localized mainly in the dental papilla and not the dental organ. These data indicate that the expression and activity of MMP-2 varies during the development and maturation of rat first molar tooth germ.
Highlights
The development and differentiation of the tooth germ is accompanied by rapid changes in its extracellular matrix [1]
Extracts of molar tooth germ of 0 to 15-day-old rats demonstrated three gelatinolytic enzymes by enzymography assay that were characterized as MMP2, because they were inhibited by 1,10-phenanthroline and EDTA, exhibited activities at a neutral pH and were extracted from the extracellular matrix containing a fraction of tooth germ (Triton X-100 insoluble)
The expression and activity of matrix metalloproteinase (MMPs)-2 increased progressively with the development of the tooth germ, and were found mainly in the dental papilla. This gradual increase of metaloproteinase de matriz-2 (MMP-2) correlates with a period of rapid morphological alterations in the dental papilla, which changes from a soft myxoid-type connective tissue found in neonates to a more fibrous stroma present in 15-day-old rats [17]
Summary
The development and differentiation of the tooth germ is accompanied by rapid changes in its extracellular matrix [1]. A novel enzyme named enamelysin (MMP20) was recently cloned from tooth tissues and was later characterized as a member of matrix metalloproteinase (MMPs) group [5]. MMPs are endopeptidases capable of degrading various macromolecules of extracellular matrix. They are secreted into the extracellular matrix in latent form and are activated by disruption of a Zn++cysteine bond by proteolysis and/or autocatalytic cleavage in the propeptide domain. The third group is formed by stromelysins 1, 2 and 3, which cleave many proteins of the extracellular matrix, such as proteoglycans, laminins, fibronectins and collagen types IV, V, IX and X [9]. Membrane-type MMPs (MT-MMP) form the fourth group. The aim of this study was to evaluate the expression and activity of MMP-2 in the rat tooth germ of newborn to 15day-old rats
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