We have previously established that membrane-type metalloproteinases (MT-MMPs) are essential for skeletal development in the mouse, where collagenolytic activity is critically dependent on MT1-MMP and MT3-MMP. Importantly, the traits associated with loss of MT1-MMP in the mouse are a remarkable phenocopy of the human disease, Winchester syndrome (OMIM # 259600), which now is identified as a homozygous mutation of the MT1-MMP locus. Due to the pleiotropic nature of MT-MMP null-mutations and the widespread expression pattern of MT-MMP in bone, bone-associated tissues and non-bone tissues, we have generated and utilized a conditional deletion mutation strain of mice. We subsequently deleted MT-MMP activity in a cell and stage-specific fashion to account for the cell and tissue specific functions of pericellular proteolysis mediated by MT-MMPs. To establish the role of MT-MMP activity in perivascular smooth muscle/pericyte-like cells, which are considered a potential reservoir of mesenchymal progenitors, we have ablated MT-MMP activity in SM22α-positive cells. Loss of MT1-MMP in this subset of cells leads to gross loss of bone in the cranium and in long bones where the trabecular and cortical bone content is dramatically reduced. Additionally, conspicuous fibrosis is associated with the diminished bone content. Together, these observations indicate that cells engaging in the formation of the skeleton to a large degree are recruited out of the perivascular cell pool and utilize MT1-MMP to exert their function. To further understand the function of pericellular proteolysis in cells committed to osteogenic fate through expression of the transcription factor, Sp7/Osx, MT1-MMP was deleted in this subset of cells. This deficit leads to overt skeletal dysmorphism and secondarily, a rampant bone resorption reminiscent of unconditional MT1-MMP deficiency. These data demonstrate that Osx positive cells and their progeny not only affect bone formation, a large component of the disease observed in universal MT1-MMP deficiency, but also regulate significant aspects of bone resorption. This observation is consistent with the ability of MT1-MMP and to cleave and shed RANKL, a critical TNFαsuperfamily member in osteoclast differentiation. Proteolysis thus works as an attenuation factor in osteoclast recruitment together with the RANKL decoy, osteoprotegerin (OPG). Next, the role of pericellular proteolysis in Osx positive progenitors was contrasted with the function of osteocalcin (Ocn) positive, mature osteoblasts. Unlike Osx specific deletion, Ocn mediated ablation of MT1-MMP leads to grossly normal mice, which however display rampant bone loss in adulthood. Thus, while progenitor mediated deletion results in dysmorphism and resorption, osteoblast specific ablation leads to mainly bone resorption. From this observation we deduce that the mature osteogenic cell mainly serves to regulate resorption through proteolysis. The hematopoietic micro-environment is critical for proper bone formation and remodeling and we have focused on the role of MT-MMP activity in this tissue compartment. Notably, skeletal cells devoid of MT-MMP activity fail to support postnatal marrow formation in ectopic bone formation. We propose that MT-MMPs plays a pivotal role in the migration and recruitment of hematopoietic stem cells and their ability to populate a potential hematopoietic environment. Accordingly, we have demonstrated that the bone marrow of MT1-MMP deficient mice retain twice as many hematopoietic stem cells (HSCs) as observed in wildtype littermates. In an effort to identify the HSC-retaining cell and the cell responsible for recruitment of HSCs to the circulation, we demonstrated that Osx-specific loss of MT1-MMP affect the mobilization of HSC to the circulation. MT-MMP activity is required in remodeling of specific unmineralized cartilages in the skeleton. Until now, it has remained unresolved if this remodeling mechanism was a property of chondrocytes or connective tissue cells adjacent to the cartilage. Using cartilage specific ablation of MT-MMP activity, we have established that chondrocytes are essential for the remodeling of the cartilages. Importantly, neighboring cells fail to remodel these unmineralized cartilages and chondrocytes are thus essential for this remodeling process. We furthermore demonstrate that the combined loss of MT1-MMP in cartilage and universal loss of MT3-MMP dramatically exacerbates the disruption of cartilage and induce a severe growth retardation and dwarfism.

Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
National Institute of Dental & Craniofacial Research
Zip Code
Daley, William P; Matsumoto, Kazue; Doyle, Andrew D et al. (2017) Btbd7 is essential for region-specific epithelial cell dynamics and branching morphogenesis in vivo. Development 144:2200-2211
Young, W Scott; Song, June; Mezey, Éva (2016) Hybridization Histochemistry of Neural Transcripts. Curr Protoc Neurosci 75:1.3.1-1.3.27
Xu, H; Snider, T N; Wimer, H F et al. (2016) Multiple essential MT1-MMP functions in tooth root formation, dentinogenesis, and tooth eruption. Matrix Biol 52-54:266-283
Motley, Michael P; Madsen, Daniel H; Jürgensen, Henrik J et al. (2016) A CCR2 macrophage endocytic pathway mediates extravascular fibrin clearance in vivo. Blood 127:1085-96
Langenfurth, Anika; Gu, Song; Bautze, Verena et al. (2016) Decreased demand for olfactory periglomerular cells impacts on neural precursor cell viability in the rostral migratory stream. Sci Rep 6:32203
Remoli, Cristina; Michienzi, Stefano; Sacchetti, Benedetto et al. (2015) Osteoblast-specific expression of the fibrous dysplasia (FD)-causing mutation Gs?(R201C) produces a high bone mass phenotype but does not reproduce FD in the mouse. J Bone Miner Res 30:1030-43
Maeda, Azusa; Ono, Mitsuaki; Holmbeck, Kenn et al. (2015) WNT1-induced Secreted Protein-1 (WISP1), a Novel Regulator of Bone Turnover and Wnt Signaling. J Biol Chem 290:14004-18
Koide, Hisashi; Holmbeck, Kenn; Lui, Julian C et al. (2015) Mice Deficient in AKAP13 (BRX) Are Osteoporotic and Have Impaired Osteogenesis. J Bone Miner Res 30:1887-95
Peters, Diane E; Szabo, Roman; Friis, Stine et al. (2014) The membrane-anchored serine protease prostasin (CAP1/PRSS8) supports epidermal development and postnatal homeostasis independent of its enzymatic activity. J Biol Chem 289:14740-9
Berendsen, Agnes D; Pinnow, Emily L; Maeda, Azusa et al. (2014) Biglycan modulates angiogenesis and bone formation during fracture healing. Matrix Biol 35:223-31

Showing the most recent 10 out of 19 publications