EXPRESSION OF 72-KDA GELATINASE (MATRIX METALLOPROTEINASE-2) IN THE DEVELOPING MOUSE CRANIOFACIAL COMPLEX

Tissue remodelling is an important feature during embryogenesis. Altho ugh the matrix metalloproteinases are believed to participate in these processes, the relation between matrix metalloproteinases and tissue remodelling during craniofacial morphogenesis remains unclear. The pur pose of the study was to look for the presence of enzymes involved in extracellular matrix degradation during craniofacial morphogenesis. Pr otein expression of the matrix metalloproteinase, 72-kDa gelatinase (m atrix metalloproteinase-2, gelatinase A, 72-kDa type IV collagenase) w as studied by gelatine zymography and by indirect immunofluorescence w ith conventional and confocal microscopy. In the anterior region of th e developing mouse face, 72-kDa gelatinase was labelled mainly in the tips and peripheral regions of the nasal and facial prominences. Upon contact and fusion of the prominences, the staining was intensely loca lized to the zone of the fusion and the tips and peripheral regions of the nasal prominences and the maxilia. The labelling of 72-kDa gelati nase was also present in the peripheral regions of the mandible, secon d branchial arch, and the face around the developing eye. However, dur ing lens vesicle formation, the staining of 72-kDa gelatinase was abse nt in the invaginated lens ectoderm. After the lens had completely det ached from the surface ectoderm, the staining was resumed in the corne al epithelium and mesenchyme. Gelatine zymography was used to confirm the presence of active and latent 72-kDa gelatinase in the developing mouse craniofacial complex. Collectively, these data indicate that 72- kDa gelatinase may play a significant part in localized tissue remodel ling during craniofacial morphogenesis and the aberrant expression or function of the enzyme could be involved in causing facial abnormaliti es. (C) 1997 Published by Elsevier Science Ltd.