Bougault Carole, Priam Sabrina, Houard Xavier, Pigenet Audrey, Sudre Laure, Lories Rik J, Jacques Claire, Berenbaum Francis
Arthritis Res Ther. 2014 Jul 1;16(4):R137. doi: 10.1186/ar4599.
Our objective was to investigate whether a lack of frizzled-related protein B (FrzB), an extracellular antagonist of the Wnt signaling pathways, could enhance cartilage degradation by facilitating the expression, release and activation of matrix metalloproteinases (MMPs) by chondrocytes in response to tissue-damaging stimuli.
Cartilage explants from FrzB-/- and wild-type mice were challenged by excessive dynamic compression (0.5 Hz and 1 MPa for 6 hours). Load-induced glycosaminoglycan (GAG) release and MMP enzymatic activity were assessed. Interleukin-1β (IL-1β) (10, 100 and 1000 pg/mL for 24 hours) was used to stimulate primary cultures of articular chondrocytes from FrzB-/- and wild-type mice. The expression and release of MMP-3 and -13 were determined by RT-PCR, western blot and ELISA. The accumulation of β-catenin was assessed by RT-PCR and western blot.
Cartilage degradation, as revealed by a significant increase in GAG release (2.8-fold, P = 0.014) and MMP activity (4.5-fold, P = 0.014) by explants, was induced by an excessive load. Load-induced MMP activity appeared to be enhanced in FrzB-/- cartilage explants compared to wild-type (P = 0.17). IL-1β dose-dependently induced Mmp-13 and -3 gene expression and protein release by cultured chondrocytes. IL-1β-mediated increase in MMP-13 and -3 was slightly enhanced in FrzB-/- chondrocytes compared to wild-type (P = 0.05 and P = 0.10 at gene level, P = 0.17 and P = 0.10 at protein level, respectively). Analysis of Ctnn1b and Lef1 gene expression and β-catenin accumulation at protein level suggests that the enhanced catabolic response of FrzB-/- chondrocytes to IL-1β and load may be associated with an over-stimulation of the canonical Wnt/β-catenin pathway.
Our results suggest that FrzB may have a protective role on cartilage degradation and MMP induction in mouse chondrocytes by attenuating deleterious effects of the activation of the canonical Wnt/β-catenin pathway.
我们的目的是研究缺乏卷曲相关蛋白B（FrzB），一种Wnt信号通路的细胞外拮抗剂，是否会通过促进软骨细胞在组织损伤刺激下基质金属蛋白酶（MMPs）的表达、释放和激活来增强软骨降解。
用过度动态压缩（0.5Hz和1MPa，持续6小时）刺激FrzB基因敲除小鼠和野生型小鼠的软骨外植体。评估负荷诱导的糖胺聚糖（GAG）释放和MMP酶活性。用白细胞介素-1β（IL-1β）（10、100和1000pg/mL，持续24小时）刺激FrzB基因敲除小鼠和野生型小鼠的原代关节软骨细胞培养物。通过逆转录-聚合酶链反应（RT-PCR）、蛋白质印迹法和酶联免疫吸附测定（ELISA）测定MMP-3和-13的表达和释放。通过RT-PCR和蛋白质印迹法评估β-连环蛋白的积累。
外植体中GAG释放显著增加（2.8倍，P = 0.014）和MMP活性显著增加（4.5倍，P = 0.014）所揭示的软骨降解是由过度负荷诱导的。与野生型相比，负荷诱导的MMP活性在FrzB基因敲除小鼠的软骨外植体中似乎增强（P = 0.17）。IL-1β剂量依赖性地诱导培养的软骨细胞中Mmp-13和-3基因表达和蛋白质释放。与野生型相比，IL-1β介导的MMP-13和-3增加在FrzB基因敲除的软骨细胞中略有增强（基因水平分别为P = 0.05和P = 0.10，蛋白质水平分别为P = 0.17和P = 0.10）。对Ctnn1b和Lef1基因表达以及蛋白质水平的β-连环蛋白积累的分析表明，FrzB基因敲除的软骨细胞对IL-1β和负荷增强的分解代谢反应可能与经典Wnt/β-连环蛋白途径的过度刺激有关。
我们的结果表明，FrzB可能通过减弱经典Wnt/β-连环蛋白途径激活的有害作用，对小鼠软骨细胞的软骨降解和MMP诱导具有保护作用。
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