Department of Orthopedic Surgery, Yijishan Hospital, Wannan Medical College, Wuhu, People's Republic of China.
Eur Rev Med Pharmacol Sci. 2013 Sep;17(17):2335-44.
Endplate degeneration leads to accelerated degeneration of the intervertebral disc. The importance of endplate chondrocytes in this process is unclear. Many cellular processes in chondrocytes are controlled by activated c-Jun N-terminal kinases (JNK) and protein kinase B (AKT). However, the involvement of their pathways in the degeneration process needs to be elucidated.
To study activation of JNK and AKT signaling pathways and their significance for degeneration of endplate chondrocytes, as well as involvement of progressive ankylosis protein (ANK) in this process.
Rat primary chondrocytes were grown to confluence and subcultured until passage 4. Morphological appearances (microscope, hematoxylin & eosin staining, toluidine blue staining) and proliferation rates of cells (MTT test) were observed. Further, levels of type II collagen, aggrecan, phosphorylated JNK and AKT, total JNK, AKT and ANK were evaluated by qPCR, flow cytometry and Western blot assays. Furthermore, inhibition experiments with SP600125, the JNK inhibitor, were carried out in the passage 4 cells to assess the effects of the JNK pathway on natural degeneration of endplate chondrocytes.
The proliferative speed of endplate chondrocytes progressively decreased during passaging. Expressions of type II collagen and aggrecan were significantly decreased with cells at higher passages. Furthermore, phosphorylation of JNK, but not AKT, was significantly up-regulated and accompanied by reduced ANK expression. Inhibition of the JNK pathway increased expression of type II collagen, aggrecan and ANK and facilitated proliferation rates.
Phosphorylation of JNK promotes natural degeneration of cervical endplate chondrocytes, likely by down-regulating ANK expression.
终板退变导致椎间盘退变加速。终板软骨细胞在这一过程中的重要性尚不清楚。软骨细胞中的许多细胞过程受激活的 c-Jun N-末端激酶（JNK）和蛋白激酶 B（AKT）控制。然而，其途径在退变过程中的参与仍需阐明。
研究 JNK 和 AKT 信号通路的激活及其对终板软骨细胞退变的意义，并探讨进展性强直蛋白（ANK）在这一过程中的作用。
将大鼠原代软骨细胞培养至汇合并传代至第 4 代。观察细胞的形态外观（显微镜、苏木精和伊红染色、甲苯胺蓝染色）和增殖率（MTT 试验）。进一步通过 qPCR、流式细胞术和 Western blot 检测 II 型胶原、聚集蛋白、磷酸化 JNK 和 AKT、总 JNK、AKT 和 ANK 的水平。此外，在第 4 代细胞中用 JNK 抑制剂 SP600125 进行抑制实验，以评估 JNK 通路对终板软骨细胞自然退变的影响。
随着传代次数的增加，终板软骨细胞的增殖速度逐渐减慢。II 型胶原和聚集蛋白的表达随着细胞传代次数的增加而显著降低。此外，JNK 的磷酸化，但不是 AKT 的磷酸化，显著上调，并伴有 ANK 表达的减少。JNK 通路的抑制增加了 II 型胶原、聚集蛋白和 ANK 的表达，并促进了增殖率。
JNK 的磷酸化促进了颈椎终板软骨细胞的自然退变，可能是通过下调 ANK 的表达。
