BMP1-like proteinases are essential to the structure and wound healing of skin
MATRIX BIOLOGY
Authors: Muir, Alison M.; Massoudi, Dawiyat; Ngon Nguyen; Keene, Douglas R.; Lee, Se-Jin; Birk, David E.; Davidson, Jeffrey M.; Marinkovich, M. Peter; Greenspan, Daniel S.
Abstract
Clbsely related extracellular metalloproteinases bone morphogenetic protein 1 (BMP1) and mammalian Tolloid-like 1 (mTLL1) are co-expressed in various tissues and have been suggested to have overlapping roles in the biosynthetic processing of extracellular matrix components. Early lethality of mice null for the BMP1 gene Bmp1 or the mTLL1 gene Till has impaired in vivo studies of these proteinases. To overcome issues of early lethality and functional redundancy we developed the novel BTKO mouse strain, with floxed Bmp1 and Till1 alleles, for induction of postnatal, simultaneous ablation of the two genes. We previously showed these mice to have a skeletal phenotype that includes elements of osteogenesis imperfecta (OI), osteomalacia, and deficient osteocyte maturation, observations validated by the finding of BMP1 mutations in a subset of human patients with OI-like phenotypes. However, the roles of BMP1-like proteinase in non-skeletal tissues have yet to be explored, despite the supposed importance of putative substrates of these proteinases in such tissues. Here, we employ BTKO mice to investigate potential roles for these proteinases in skin. Loss of BMP1-like proteinase activity is shown to result in markedly thinned and fragile skin with unusually densely packed collagen fibrils and delayed wound healing. We demonstrate deficits in the processing of collagens 1 and III, decorin, biglycan, and laminin 332 in skin, which indicate mechanisms whereby BMP1-like proteinases affect the biology of this tissue. In contrast, lack of effects on collagen VII processing or deposition indicates this putative substrate to be biosynthetically processed by non-BMP1-like proteinases. (C) 2016 Elsevier B.V. All rights reserved.
Regulation of BMP signaling by the BMP1/TLD-related metalloprotease, SpAN
DEVELOPMENTAL BIOLOGY
Authors: Wardle, FC; Angerer, LM; Angerer, RC; Dale, L
Abstract
We have used the Xenopus embryo as a test system for analyzing the activity of SpAN, a sea urchin metalloprotease in the astacin family containing BMP1 and tolloid. Embryos expressing SpAN initiated gastrulation on a time scale indistinguishable from controls, but invagination of the vegetal pole was subsequently delayed by several hours. At tailbud stages the most severely affected embryos were completely ventralized, lacking all dorsal structures. Molecular analysis of injected embryos, using probes for both dorsal (xgsc and xnot) and ventral (xhox3 and xwnt8) mesoderm, indicates that SpAN ventralizes dorsal mesoderm during gastrula stages. These results mirror those previously obtained with BMP4, suggesting that SpAN may enhance the activity of this ventralizing factor. Consistent with this suggestion, we have shown that SpAN blocks the dorsalizing activity of noggin and chordin, two inhibitory binding proteins for BMP4, but not that of a dominant-negative receptor for BMP4. In contrast, a dominant-negative SpAN, in which the metalloprotease domain has been deleted, dorsalizes ventral mesoderm, a phenotype that can be rescued by coexpressing either SpAN or XBMP1. This suggests that SpAN is mimicking a Xenopus metalloprotease responsible for regulating the activity of Xenopus BMPs during gastrulation. Moreover, our results raise the possibility that SpAN may function to facilitate BMP signaling in early sea urchin embryos. (C) 1999 Academic Press.