Multiple signals induce endoplasmic reticulum stress in both primary and immortalized chondrocytes resulting in loss of differentiation, impaired cell growth, and apoptosis
Multiple signals induce endoplasmic reticulum stress in both primary and immortalized chondrocytes resulting in loss of differentiation, impaired cell growth, and apoptosis
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DOI：
10.1074/jbc.m501069200
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发表时间：
2005-09-02
影响因子：
4.8
通讯作者：
Horton, WE
中科院分区：
文献类型：
--
作者：
Yang, L;Carlson, SG;Horton, WE
内质网是分泌蛋白质合成和折叠的场所，对细胞内外环境的变化敏感。生理和病理条件都可能扰乱内质网的功能，导致内质网应激。软骨细胞是软骨中唯一的常驻细胞，负责合成和周转丰富的细胞外基质，并可能对内质网应激敏感。在这里，我们报告，葡萄糖戒断，衣霉素，和毒胡萝卜素诱导上调GADD 153和半胱天冬酶-12，内质网应激的两个标志物，在原代软骨细胞和软骨细胞系。其他药物如白细胞介素-1 β或肿瘤坏死因子α分别诱导极轻微或不诱导GADD 153。内质网应激导致基于细胞计数的软骨细胞生长减少、p21上调和PCNA表达减少。此外，内质网功能的扰动导致软骨细胞的阿辛蓝阳性基质的积累减少，并在蛋白质水平上降低II型胶原的表达。此外，定量实时PCR被用来证明在暴露于内质网应激诱导条件下的软骨细胞中编码聚集蛋白聚糖、胶原蛋白II和连接蛋白的稳态mRNA水平的下调。最终，内质网应激导致软骨细胞凋亡，如DNA片段化和膜联蛋白V染色所证明的。这些发现对软骨生物学中内质网应激的后果具有潜在的重要意义。
The endoplasmic reticulum is the site of synthesis and folding of secretory proteins and is sensitive to changes in the internal and external environment of the cell. Both physiological and pathological conditions may perturb the function of the endoplasmic reticulum, resulting in endoplasmic reticulum stress. The chondrocyte is the only resident cell found in cartilage and is responsible for synthesis and turnover of the abundant extracellular matrix and may be sensitive to endoplasmic reticulum stress. Here we report that glucose withdrawal, tunicamycin, and thapsigargin induce up-regulation of GADD153 and caspase-12, two markers of endoplasmic reticulum stress, in both primary chondrocytes and a chondrocyte cell line. Other agents such as interleukin-1 beta or tumor necrosis factor alpha induced a minimal or no induction of GADD153, respectively. The endoplasmic reticulum stress resulted in decreased chondrocyte growth based on cell counts, up-regulation of p21, and decreased PCNA expression. In addition, perturbation of endoplasmic reticulum function resulted in decreased accumulation of an Alcian Blue positive matrix by chondrocytes and decreased expression of type II collagen at the protein level. Further, quantitative realtime PCR was used to demonstrate a down-regulation of steady state mRNA levels coding for aggrecan, collagen II, and link protein in chondrocytes exposed to endoplasmic reticulum stress-inducing conditions. Ultimately, endoplasmic reticulum stress resulted in chondrocyte apoptosis, as evidenced by DNA fragmentation and annexin V staining. These findings have potentially important implications regarding consequences of endoplasmic reticulum stress in cartilage biology.