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Site-specific expression of gelatinolytic activity during morphogenesis of the secondary palate in the mouse embryo.

Gkantidis N, Blumer S, Katsaros C, Graf D, Chiquet M - PLoS ONE (2012)

Bottom Line: Gelatinolytic activity at this site was not the consequence of epithelial fold formation, as it was also observed in Bmp7-deficient embryos where shelf elevation is delayed.In this case, gelatinolytic activity appeared in vertical shelves at the exact position where the epithelial fold will form during elevation.Mmp2 and Mmp14 (MT1-MMP), but not Mmp9 and Mmp13, mRNAs were expressed in the mesenchyme around the epithelial folds of the elevated palatal shelves; this was confirmed by immunostaining for MMP-2 and MT1-MMP.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthodontics and Dentofacial Orthopedics, School of Dental Medicine, University of Bern, Bern, Switzerland.

ABSTRACT
Morphogenesis of the secondary palate in mammalian embryos involves two major events: first, reorientation of the two vertically oriented palatal shelves into a horizontal position above the tongue, and second, fusion of the two shelves at the midline. Genetic evidence in humans and mice indicates the involvement of matrix metalloproteinases (MMPs). As MMP expression patterns might differ from sites of activity, we used a recently developed highly sensitive in situ zymography technique to map gelatinolytic MMP activity in the developing mouse palate. At embryonic day 14.5 (E14.5), we detected strong gelatinolytic activity around the lateral epithelial folds of the nasopharyngeal cavity, which is generated as a consequence of palatal shelf elevation. Activity was concentrated in the basement membrane of the epithelial fold but extended into the adjacent mesenchyme, and increased in intensity with lateral outgrowth of the cavity at E15.5. Gelatinolytic activity at this site was not the consequence of epithelial fold formation, as it was also observed in Bmp7-deficient embryos where shelf elevation is delayed. In this case, gelatinolytic activity appeared in vertical shelves at the exact position where the epithelial fold will form during elevation. Mmp2 and Mmp14 (MT1-MMP), but not Mmp9 and Mmp13, mRNAs were expressed in the mesenchyme around the epithelial folds of the elevated palatal shelves; this was confirmed by immunostaining for MMP-2 and MT1-MMP. Weak gelatinolytic activity was also found at the midline of E14.5 palatal shelves, which increased during fusion at E15.5. Whereas MMPs have been implicated in palatal fusion before, this is the first report showing that gelatinases might contribute to tissue remodeling during early stages of palatal shelf elevation and formation of the nasopharynx.

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Codistribution of MMP immunostaining with gelatinolytic activity in and around the basement membrane of the palatal fold.Frontal cryosections of E15.5 wild type mouse heads were subjected to DQ-gelatin zymography (A, D), followed by immunofluorescence labeling for MMP-2 (B) or MT1-MMP (E) on the same section. Merged images are shown in C and F. Note colocalization of MMPs with gelatinolytic activity in and around the basement membrane of the epithelial fold (arrows) that is formed above the palatal shelf after its elevation. MMP-2 expression is also evident at the luminal surface of the epithelium where there is no gelatinolysis (arrowheads). For more details, see Results. p, palatal shelf; n, nasal floor; np, nasopharynx. Bar, 50 μm.
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pone-0047762-g009: Codistribution of MMP immunostaining with gelatinolytic activity in and around the basement membrane of the palatal fold.Frontal cryosections of E15.5 wild type mouse heads were subjected to DQ-gelatin zymography (A, D), followed by immunofluorescence labeling for MMP-2 (B) or MT1-MMP (E) on the same section. Merged images are shown in C and F. Note colocalization of MMPs with gelatinolytic activity in and around the basement membrane of the epithelial fold (arrows) that is formed above the palatal shelf after its elevation. MMP-2 expression is also evident at the luminal surface of the epithelium where there is no gelatinolysis (arrowheads). For more details, see Results. p, palatal shelf; n, nasal floor; np, nasopharynx. Bar, 50 μm.

Mentions: Higher magnification double labeling images revealed extensive colocalization of MMP-2 and MT1-MMP with gelatinolytic activity around the nasopharyngeal fold above the palate at E15.5 (Fig. 9). MMP-2 protein overlapped with activity both in epithelial basement membrane and palatal mesenchyme; in addition significant amounts of latent MMP-2 were evident at the luminal surface of the epithelium where no activity was detected (Fig. 9A–C). MT1-MMP colocalized with activity primarily in palatal mesenchyme adjacent to the epithelial fold (Fig. 9D–F). Thus, the asymmetric distribution of gelatinolytic activity around the nasopharyngeal fold (c.f. Fig. 4) was matched by MMP-2 and MT1-MMP expression patterns.


Site-specific expression of gelatinolytic activity during morphogenesis of the secondary palate in the mouse embryo.

Gkantidis N, Blumer S, Katsaros C, Graf D, Chiquet M - PLoS ONE (2012)

Codistribution of MMP immunostaining with gelatinolytic activity in and around the basement membrane of the palatal fold.Frontal cryosections of E15.5 wild type mouse heads were subjected to DQ-gelatin zymography (A, D), followed by immunofluorescence labeling for MMP-2 (B) or MT1-MMP (E) on the same section. Merged images are shown in C and F. Note colocalization of MMPs with gelatinolytic activity in and around the basement membrane of the epithelial fold (arrows) that is formed above the palatal shelf after its elevation. MMP-2 expression is also evident at the luminal surface of the epithelium where there is no gelatinolysis (arrowheads). For more details, see Results. p, palatal shelf; n, nasal floor; np, nasopharynx. Bar, 50 μm.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3472992&req=5

pone-0047762-g009: Codistribution of MMP immunostaining with gelatinolytic activity in and around the basement membrane of the palatal fold.Frontal cryosections of E15.5 wild type mouse heads were subjected to DQ-gelatin zymography (A, D), followed by immunofluorescence labeling for MMP-2 (B) or MT1-MMP (E) on the same section. Merged images are shown in C and F. Note colocalization of MMPs with gelatinolytic activity in and around the basement membrane of the epithelial fold (arrows) that is formed above the palatal shelf after its elevation. MMP-2 expression is also evident at the luminal surface of the epithelium where there is no gelatinolysis (arrowheads). For more details, see Results. p, palatal shelf; n, nasal floor; np, nasopharynx. Bar, 50 μm.
Mentions: Higher magnification double labeling images revealed extensive colocalization of MMP-2 and MT1-MMP with gelatinolytic activity around the nasopharyngeal fold above the palate at E15.5 (Fig. 9). MMP-2 protein overlapped with activity both in epithelial basement membrane and palatal mesenchyme; in addition significant amounts of latent MMP-2 were evident at the luminal surface of the epithelium where no activity was detected (Fig. 9A–C). MT1-MMP colocalized with activity primarily in palatal mesenchyme adjacent to the epithelial fold (Fig. 9D–F). Thus, the asymmetric distribution of gelatinolytic activity around the nasopharyngeal fold (c.f. Fig. 4) was matched by MMP-2 and MT1-MMP expression patterns.

Bottom Line: Gelatinolytic activity at this site was not the consequence of epithelial fold formation, as it was also observed in Bmp7-deficient embryos where shelf elevation is delayed.In this case, gelatinolytic activity appeared in vertical shelves at the exact position where the epithelial fold will form during elevation.Mmp2 and Mmp14 (MT1-MMP), but not Mmp9 and Mmp13, mRNAs were expressed in the mesenchyme around the epithelial folds of the elevated palatal shelves; this was confirmed by immunostaining for MMP-2 and MT1-MMP.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthodontics and Dentofacial Orthopedics, School of Dental Medicine, University of Bern, Bern, Switzerland.

ABSTRACT
Morphogenesis of the secondary palate in mammalian embryos involves two major events: first, reorientation of the two vertically oriented palatal shelves into a horizontal position above the tongue, and second, fusion of the two shelves at the midline. Genetic evidence in humans and mice indicates the involvement of matrix metalloproteinases (MMPs). As MMP expression patterns might differ from sites of activity, we used a recently developed highly sensitive in situ zymography technique to map gelatinolytic MMP activity in the developing mouse palate. At embryonic day 14.5 (E14.5), we detected strong gelatinolytic activity around the lateral epithelial folds of the nasopharyngeal cavity, which is generated as a consequence of palatal shelf elevation. Activity was concentrated in the basement membrane of the epithelial fold but extended into the adjacent mesenchyme, and increased in intensity with lateral outgrowth of the cavity at E15.5. Gelatinolytic activity at this site was not the consequence of epithelial fold formation, as it was also observed in Bmp7-deficient embryos where shelf elevation is delayed. In this case, gelatinolytic activity appeared in vertical shelves at the exact position where the epithelial fold will form during elevation. Mmp2 and Mmp14 (MT1-MMP), but not Mmp9 and Mmp13, mRNAs were expressed in the mesenchyme around the epithelial folds of the elevated palatal shelves; this was confirmed by immunostaining for MMP-2 and MT1-MMP. Weak gelatinolytic activity was also found at the midline of E14.5 palatal shelves, which increased during fusion at E15.5. Whereas MMPs have been implicated in palatal fusion before, this is the first report showing that gelatinases might contribute to tissue remodeling during early stages of palatal shelf elevation and formation of the nasopharynx.

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