Matrix metalloproteinase 13 loss associated with impaired extracellular matrix remodeling disrupts chondrocyte differentiation by concerted effects on multiple regulatory factors

Abstract

Objective. To link matrix metalloproteinase 13 (MMP-13) activity and extracellular matrix (ECM) remodeling to alterations in regulatory factors leading to a disruption in chondrocyte homeostasis.Methods. MMP-13 expression was ablated in primary human chondrocytes by stable retrotransduction of short hairpin RNA. The effects of MMP-13 knockdown on key regulators of chondrocyte differentiation (SOX9, runt-related transcription factor 2 [RUNX-2], and ␤-catenin) and angiogenesis (vascular endothelial growth factor [VEGF]) were scored at the protein level (by immunohistochemical or Western blot analysis) and RNA level (by real-time polymerase chain reaction) in high-density monolayer and micromass cultures under mineralizing conditions. Effects on cellular viability in conjunction with chondrocyte progression toward a hypertrophic-like state were assessed in micromass cultures. Alterations in SOX9 subcellular distribution were assessed using confocal microscopy in micromass cultures and also in osteoarthritic cartilage.Results. Differentiation of control chondrocyte micromasses progressed up to a terminal phase, with calcium deposition in conjunction with reduced cell viability and scant ECM. MMP-13 knockdown impaired ECM remodeling and suppressed differentiation in conjunction with reduced levels of RUNX-2, ␤-catenin, and VEGF. MMP-13 levels in vitro and ECM remodeling in vitro and in vivo were linked to changes in SOX9 subcellular localization. SOX9 was largely excluded from the nuclei of chondrocytes with MMP-13-remodeled or -degraded ECM, and exhibited an intranuclear staining pattern in chondrocytes with impaired MMP-13 activity in vitro or with more intact ECM in vivo.Conclusion. MMP-13 loss leads to a breakdown in primary human articular chondrocyte differentiation by altering the expression of multiple regulatory factors.The maturation of chondrocytes is arrested in articular cartilage, which prevents their differentiation toward a more terminal hypertrophic-like phenotype (1). The mechanisms maintaining articular chondrocyte homeostasis are perturbed in osteoarthritis (OA), in which chondrocytes recapitulate aspects of endochon-

Keratocytes Create Stromal Spaces to Promote Corneal Neovascularization Via MMP13 Expression

“…40,41 However, there is a discrepancy regarding the correlation between VEGFa and MMP13 because some reports have showed that MMP13 could promote VEGFa expression or release from chondrocytes, fibroblasts, endothelial cells, and the ECM. 4,44,45 In the present study, we showed that the expression of VEGFa and VEGFr2 mRNAs and proteins was not significantly different in rat corneas before and after alkali burns, although they were indeed clearly detected via qRT-PCR and WB. Furthermore, we found that VEGFa had little effect on MMP13 gene transcription via MMP13 promoter assay.…”

“…1,2,43 Previous studies have indicated that VEGFa is correlated with MMP13 expression. 4,41,44,45 However, the correlation between VEGFc and MMP13 expression has not yet been reported. Because VEGFa, VEGFc, VEGFr2, and VEGFr3 have all been showed to be expressed in the cornea, in addition to VECs, 1,2,46,47 we investigated whether their expression was related to MMP13 expression in alkali-burned rat corneas via qRT-PCR and WB.…”

Roles of inflammatory and anabolic cytokines in cartilage metabolism: signals and multiple effectors converge upon MMP-13 regulation in osteoarthritis

“…Although our collective published work has uncovered important roles of specific transcription factors and their upstream signaling modules in common aspects of chondrocyte differentiation and OA disease development (Ijiri et al , 2005; Olivotto et al , 2008; Peng et al , 2008; Borzì et al , 2010; Tsuchimochi et al , 2010), it remains necessary if not essential to uncover the environmental and genetic factors that work in concert to alter the molecular interplay between different transcriptional and signaling networks to “funnel” them into an overriding, common pathway of irreversible cartilage destruction.…”

Multiple myeloma–derived MMP-13 mediates osteoclast fusogenesis and osteolytic disease

“…MMP-13 is a member of a family of zinc-and calcium-dependent proteolytic enzymes that degrade extracellular matrix components during normal physiological processes (e.g., embryonic development, reproduction, tissue remodeling, and angiogenesis) as well as in pathological conditions such as osteoarthritis, tumor invasion, and metastasis (8,9). In each of these scenarios, the key functional activities of MMP-13 have been linked directly to its ability to degrade interstitial collagen, a critical structural component of all connective tissues, including bone, as well as other matrix-associated targets (10)(11)(12)(13)(14)(15)(16)(17)(18)(19). However, in contrast to studies highlighting the degradative activities of the metalloproteinase, we now report that MM-derived MMP-13 serves as a potent secretagogue of OCL fusion and bone-resorptive activity independently of its proteolytic activity by triggering the ERK1/2-dependent regulation of nuclear factor of activated T cells, cytoplasmic, calcineurin-dependent 1 (NFATc1) and dendrocyte-expressed 7 transmembrane (DC-STAMP) expression.…”