A dual MMP9/MMP14 Axis Regulates Osteoclast Bone Resorptive Function

MMP 9/MMP 14双轴调控破骨细胞骨吸收功能 摘要 破骨细胞（OC）的过度活动是导致骨质疏松症等多种骨骼疾病的原因， 和类风湿性关节炎到肿瘤引起的骨质溶解。尽管开发了几种抗吸收剂， 然而，在治疗药物中，它们的姑息作用通常是有限的或伴随着不希望的副作用。在这方面，委员会注意到， 由于组织蛋白酶K作为胶原溶解酶的关键作用， 降解I型胶原蛋白，骨细胞外基质的主要蛋白质成分。有趣的是， 然而，OC也表达基质金属蛋白酶，其在OC骨吸收活性中功能仍然存在， 大部分未定义。在此，我们利用无偏转录组筛选作为威尔斯离体测定来鉴定 MMP 9和MMP 14是OC表达的两种主要MMP。然而，在生成Mmp 9-/-或Mmp 9-/-之后， 骨髓特异性Csf 1 r-Cre/Mmp 14 f/f OCs，初步研究表明，两种蛋白酶都不起关键作用， 骨吸收出乎意料的是，我们发现Csf 1 r-Cre/Mmp 14 f/f/Mmp 9-/-双敲除的OC表现出主要的 体外和体内骨吸收缺陷。在努力定义一个组合的基础机制， OC功能对MMP 9和MMP 14的需求，野生型与双敲除OC的初步分析 基因表达鉴定了碳水化合物代谢、锌指结合和 你好这些发现使我们重新认识并确认，MMP 9和MMP 14共同发挥着关键作用。 在调节锌指转录抑制因子Zeb 1-仲裁代谢途径以控制OC活化中的作用 与MMPs介导骨胶原溶解作用的能力相关联。因此，我们建议i）描述 MMP 9/MMP 14在体内外控制破骨细胞功能和骨吸收中的协同作用， 利用骨髓特异性和OC特异性条件性敲除小鼠，ii）鉴定新的MMP 9/MMP 14-Zeb 1轴 在体外和体内调节能量代谢和破骨细胞活性，和iii）定义的双重作用， 半乳糖凝集素-3膜晶格的MMP 9/MMP 14共依赖性蛋白水解作为Zeb 1的上游，与 骨I型胶原溶解调节破骨细胞骨吸收功能。独特的蛋白水解和代谢 该提案中概述的信号途径应该为OC介导的骨重建提供新的见解， 推进对旨在预防病理性骨丢失的改进治疗策略的研究。

A dual MMP9/MMP14 Axis Regulates Osteoclast Bone Resorptive Function Abstract Excessive osteoclast (OC) activity is responsible for a wide range of bone diseases, ranging from osteoporosis and rheumatoid arthritis to tumor-induced osteolysis. Despite the development of several anti-resorptive therapeutics, their palliative effects are often limited or accompanied by unwanted side effects. In this regard, cathepsin K has been targeted for therapeutic intervention given its key role as a collagenolytic enzyme capable of degrading type I collagen, the dominant protein component of the bone extracellular matrix. Interestingly, however, OCs also express matrix metalloproteinases whose function in OC bone-resorptive activity remains largely undefined. Herein, we utilized unbiased transcriptome screening as wells as ex vivo assays to identify MMP9 and MMP14 as the two dominant MMPs expressed by OCs. However, after generating Mmp9-/- or myeloid-specific Csf1r-Cre/Mmp14f/f OCs, preliminary studies suggest that neither proteinase plays a key role in bone resorption. Unexpectedly, we find that Csf1r-Cre/Mmp14f/f/Mmp9-/- double knockout OCs display major defects in bone resorption in vitro and in vivo. In an effort to define the mechanisms underlying a combined requirement for MMP9 and MMP14 in OC function, preliminary analysis of wild-type versus double knockout OC gene expression identified unexpected alterations in carbohydrate metabolism, zinc finger binding and mitochondrion. These findings led us to posit and confirm that working together, MMP9 and MMP14 play a critical role in regulating a zinc finger transcription repressor Zeb1-arbitrated metabolic pathway to govern OC activation in tandem with the ability of the MMPs to mediate bone collagenolytic effects. Thus, we propose to i) characterize the cooperative role of MMP9/MMP14 in controlling osteoclast function and bone resorption in vitro and in vivo, utilizing both myeloid- and OC-specific conditional knockout mice, ii) identify a novel MMP9/MMP14-Zeb1 axis in regulating energy metabolism and osteoclast activity in vitro and in vivo, and iii) Define the dual roles of the MMP9/MMP14 co-dependent proteolysis of galectin-3 membrane lattice as upstream of Zeb1, in parallel with bone type I collagenolysis in regulating osteoclast bone-resorptive function. The unique proteolytic and metabolic signaling route outlined in this proposal should provide new insights into OC-mediated bone remodeling, and advance the search for improved therapeutic strategies designed to prevent pathologic bone loss.