MMP20, KLK4, and MMP20/KLK4 double null mice define roles for matrix proteases during dental enamel formation.

摘要: Matrix metalloproteinase 20 (MMP20) and kallikrein-related peptidase 4 (KLK4) are secreted proteinases that essential for proper dental enamel formation. We characterized compared formed in wild-type, Mmp20 (-/-), Klk4 (+/-) (+/-), (-/-) mice using dissecting and light microscopy, backscattered scanning electron microscopy (bSEM), SEM, microcomputed tomography (μCT), energy-dispersive X-ray analysis (EDX). Following eruption, fractures were observed on molars. Failure of the molars was unexpected suggested digenic effects could contribute to etiology amelogenesis imperfecta humans. Micro-CT analyses hemimandibles demonstrated significantly reduced high-density volume relative which further mice. bSEM images 7-week mandibular incisors showed rough, pitted surfaces with numerous indentations protruding nodules. The prominent, evenly spaced, horizontal ridges more distinct due darkening valleys between ridges. In cross sections, exhibited three layers. outer layer a disturbed elemental composition an irregular surface covered null apparently unable withstand sheer forces associated eruption separated from dentin during development. Cells invaded cracks interposed MMP20 KLK4 serve overlapping complementary functions harden by removing protein, but potentially serves multiple additional necessary adherence dentin, release intercellular protein stores into matrix, retreat ameloblasts facilitate thickening layer, timely transition maturation.