Changes in catheptic activity in the enamel organ of the bovine tooth germ during development

Sakamoto, Shigemi; Sasaki, Satoshi

doi:10.1016/0003-9969(69)90273-8

Cited by 7 publications

(2 citation statements)

References 13 publications

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“…Thus, a role for proteinases in the degradation and export of enamel proteins was advanced. Lysosomes were observed histologically in ameloblasts (Reith, 1963), proteolytic activity was demonstrated in the enamel organ (Sakamoto and Sasaki, 1969), and it was proposed that lysosomal enzymes may be secreted into the enamel matrix (Katchburian and Holt, 1969). Proteolytic activity was also demonstrated within the forming enamel of sixto eight-day-old rats (Suga, 1970).…”

Section: Enamel Proteinasesmentioning

confidence: 99%

Proteinases in Developing Dental Enamel

Bartlett¹,

Simmer

1999

Critical Reviews in Oral Biology & Medicine

250

242

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For almost three decades, proteinases have been known to reside within developing dental enamel. However, identification and characterization of these proteinases have been slow and difficult, because they are present in very small quantities and they are difficult to purify directly from the mineralizing enamel. Enamel matrix proteins such as amelogenin, ameloblastin, and enamelin are cleaved by proteinases soon after they are secreted, and their cleavage products accumulate in the deeper, more mature enamel layers, while the full-length proteins are observed only at the surface. These results suggest that proteinases are necessary for "activating" enamel proteins so the parent proteins and their cleavage products may perform different functions. A novel matrix metalloproteinase named enamelysin (MMP-20) was recently cloned from tooth tissues and was later shown to localize primarily within the most recently formed enamel. Furthermore, recombinant porcine enamelysin was demonstrated to cleave recombinant porcine amelogenin at virtually all of the sites that have previously been described in vivo. Therefore, enamelysin is at least one enzyme that may be important during early enamel development. As enamel development progresses to the later stages, a profound decrease in the enamel protein content is observed. Proteinases have traditionally been assumed to degrade the organic matrix prior to its removal from the enamel. Recently, a novel serine proteinase named enamel matrix serine proteinase-l (EMSPI) was cloned from enamel organ epithelia. EMSP1 localizes primarily to the early maturation stage enamel and may, therefore, be involved in the degradation of proteins prior to their removal from the maturing enamel. Other, as yet unidentified, proteinases and proteinase inhibitors are almost certainly present within the forming enamel and await discovery.

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Section: Enamel Proteinasesmentioning

confidence: 99%

Proteinases in Developing Dental Enamel

Bartlett¹,

Simmer

1999

Critical Reviews in Oral Biology & Medicine

250

242

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“…3.4.22.1] (13), cathepsin D [E.C.3.4.23.5] (14) and dipeptidyl‐peptidase II (DPPII) [E.C.3.4.14.2] (15), have been detected in the enamel organ. Of these, only cathepsin D has been quantified as to its specific activity in enamel organ (16).…”

mentioning

confidence: 99%

Dipeptidyl‐peptidase II and cathepsin B activities in amelogenesis of the rat incisor

Smid

Young

Monsour

2001

European J Oral Sciences

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A body of published evidence suggests that a significant portion of enamel matrix protein synthesized by ameloblasts localises in the lysosomal-endosomal organelles of these enamel organ cells. Little is known regarding the lysosomal proteolytic activities during amelogenesis. The aims of this study were to detect and measure the activities of lysosomal peptidases cathepsin B (E.C. 3.4.22.1) and dipeptidyl-peptidase II (E.C. 3.4.14.2) in the enamel organ of the rat incisor and to ascertain whether rat enamel matrix proteins are degraded by these peptidases in vitro. Whole enamel organs were dissected from rat mandibular incisors. Enamel protein was also collected from the rat teeth. Analysis indicated that the rat incisor enamel organs contained specific activities of both dipeptidyl-peptidase II and cathepsin B at levels comparable with those of kidney which is rich in both these lysosomal peptidases. Gel electrophoresis and immunoblotting demonstrated that both cathepsin B and dipeptidyl-peptidase II were able to substantially degrade the rat enamel proteins in vitro. Based on these observations, we propose that lysosomal proteases have roles in amelogenesis in the intracellular degradation of amelogenins.

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