Cooperation of two ADAMTS metalloproteases in closure of the mouse palate identifies a requirement for versican proteolysis in regulating palatal mesenchyme proliferation

• Published in: Development (Cambridge) Vol. 137; no. 23; pp. 4029 - 4038
• Main Authors: Enomoto, Hiroyuki, Nelson, Courtney M., Somerville, Robert P. T., Mielke, Katrina, Dixon, Laura J., Powell, Kimerly, Apte, Suneel S.
• Format: Journal Article
• Language: English
• Published: England Company of Biologists 01.12.2010
• Subjects: ADAM Proteins - deficiency; ADAM Proteins - genetics; ADAM Proteins - metabolism; ADAMTS Proteins; ADAMTS9 Protein; Animals; Animals, Newborn; Cell Count; Cell Lineage - genetics; Cell Proliferation; Cleft Palate - enzymology; Cleft Palate - pathology; Gene Expression Regulation, Developmental; Gene Expression Regulation, Enzymologic; Mesoderm - enzymology; Mesoderm - pathology; Mesoderm - ultrastructure; Mice; Mice, Inbred C57BL; Mutation - genetics; Organogenesis - genetics; Palate - enzymology; Palate - pathology; Palate - ultrastructure; Protein Processing, Post-Translational; RNA, Messenger - genetics; RNA, Messenger - metabolism; Versicans - metabolism
• ISSN: 0950-1991; 1477-9129; 1477-9129
• DOI: 10.1242/dev.050591

We have identified a role for two evolutionarily related, secreted metalloproteases of the ADAMTS family, ADAMTS20 and ADAMTS9, in palatogenesis. Adamts20 mutations cause the mouse white-spotting mutant belted (bt), whereas Adamts9 is essential for survival beyond 7.5 days gestation (E7.5). Functional overlap of Adamts9 with Adamts20 was identified using Adamts9+/–;bt/bt mice, which have a fully penetrant cleft palate. Palate closure was delayed, although eventually completed, in both Adamts9+/–;bt/+ and bt/bt mice, demonstrating cooperation of these genes. Adamts20 is expressed in palatal mesenchyme, whereas Adamts9 is expressed exclusively in palate microvascular endothelium. Palatal shelves isolated from Adamts9+/–;bt/bt mice fused in culture, suggesting an intact epithelial TGFβ3 signaling pathway. Cleft palate resulted from a temporally specific delay in palatal shelf elevation and growth towards the midline. Mesenchyme of Adamts9+/–;bt/bt palatal shelves had reduced cell proliferation, a lower cell density and decreased processing of versican (VCAN), an extracellular matrix (ECM) proteoglycan and ADAMTS9/20 substrate, from E13.5 to E14.5. Vcan haploinsufficiency led to greater penetrance of cleft palate in bt mice, with a similar defect in palatal shelf extension as Adamts9+/–;bt/bt mice. Cell density was normal in bt/bt;Vcanhdf/+ mice, consistent with reduced total intact versican in ECM, but impaired proliferation persisted in palate mesenchyme, suggesting that ADAMTS-cleaved versican is required for cell proliferation. These findings support a model in which cooperative versican proteolysis by ADAMTS9 in vascular endothelium and by ADAMTS20 in palate mesenchyme drives palatal shelf sculpting and extension.