生长软骨细胞分化进程之间的机制关系,基质矿化,氧化代谢,在ATDC5鼠软骨祖细胞细胞系中检查了线粒体的含量和结构。软骨细胞分化的进展与氧化磷酸化的显著增加(p≤0.05)~2倍相关。然而,随着基质矿化的进展,氧化代谢下降。在没有矿化的情况下,软骨细胞外基质mRNA表达Col2a1,Aggrecan,和Col10a1在统计学上(p≤0.05)比矿化培养物中观察到的高2-3倍。相比之下,与促进基质矿化相关的BSP和Phex在统计学上(p≤0.05)显示出较高的〜2-4表达,而FGF23磷酸盐调节因子在矿化培养物中显著较低(~50%)。在非矿化和矿化培养基条件下诱导分化的培养物显示出统计学上更高的基础氧化代谢和ATP产生。与矿化的培养物相比,分化的非矿化培养物中的最大呼吸和备用氧化能力显着提高(p≤0.05)。氧化代谢增加与每个细胞的线粒体体积增加和线粒体融合有关,而矿化减少了线粒体体积,似乎与裂变有关。未分化和矿化的细胞显示与肌动蛋白细胞骨架的线粒体共定位增加。检测与线粒体分裂、凋亡和线粒体自噬相关的蛋白质,分别,在矿化培养物中,免疫表达水平与裂变和凋亡的增加一致。这些结果表明,软骨细胞分化与细胞内结构重组有关,促进线粒体含量增加和融合,从而增加氧化代谢。矿化,然而,不需要来自氧化代谢的能量;相反,在矿化过程中,线粒体似乎经历裂变和线粒体自噬。总之,这些研究表明,当软骨细胞经历肥大分化时,它们增加了氧化代谢,但是随着矿化的进行,新陈代谢下降。线粒体结构也经历了结构重组,这进一步支持了软骨细胞分化过程中的氧化能力。因此,线粒体首先进行融合以支持氧化代谢增加,然后在矿化过程中发生裂变,促进他们的程序化死亡。
The mechanistic relationships between the progression of growth chondrocyte differentiation, matrix mineralization, oxidative metabolism, and mitochondria content and structure were examined in the ATDC5 murine chondroprogenitor cell line. The progression of chondrocyte differentiation was associated with a statistically significant (p ≤ 0.05) ~2-fold increase in oxidative phosphorylation. However, as matrix mineralization progressed, oxidative metabolism decreased. In the absence of mineralization, cartilage extracellular matrix mRNA expression for Col2a1, Aggrecan, and Col10a1 were statistically (p ≤ 0.05) ~2-3-fold greater than observed in mineralizing cultures. In contrast, BSP and Phex that are associated with promoting matrix mineralization showed statistically (p ≤ 0.05) higher ~2-4 expression, while FGF23 phosphate regulatory factor was significantly lower (~50%) in mineralizing cultures. Cultures induced to differentiate under both nonmineralizing and mineralizing media conditions showed statistically greater basal oxidative metabolism and ATP production. Maximal respiration and spare oxidative capacity were significantly elevated (p ≤ 0.05) in differentiated nonmineralizing cultures compared to those that mineralized. Increased oxidative metabolism was associated with both an increase in mitochondria volume per cell and mitochondria fusion, while mineralization diminished mitochondrial volume and appeared to be associated with fission. Undifferentiated and mineralized cells showed increased mitochondrial co-localization with the actin cytoskeletal. Examination of proteins associated with mitochondria fission and apoptosis and mitophagy, respectively, showed levels of immunological expression consistent with the increasing fission and apoptosis in mineralizing cultures. These results suggest that chondrocyte differentiation is associated with intracellular structural reorganization, promoting increased mitochondria content and fusion that enables increased oxidative metabolism. Mineralization, however, does not need energy derived from oxidative metabolism; rather, during mineralization, mitochondria appear to undergo fission and mitophagy. In summary, these studies show that as chondrocytes underwent hypertrophic differentiation, they increased oxidative metabolism, but as mineralization proceeds, metabolism decreased. Mitochondria structure also underwent a structural reorganization that was further supportive of their oxidative capacity as the chondrocytes progressed through their differentiation. Thus, the mitochondria first underwent fusion to support increased oxidative metabolism, then underwent fission during mineralization, facilitating their programed death.