Park Eun Hee, Kang Shin-Sung, Lee Young-Sup, Kim Song-Ja, Jin Eun-Jung, Tak Eun Nam, Sonn Jong Kyung
Department of Biology, College of Natural Sciences, Kyungpook National University, 1370 Sankyuck-dong, Buk-gu, Daegu 702-701, South Korea.
Cell Biol Int. 2008 Oct;32(10):1272-8. doi: 10.1016/j.cellbi.2008.07.013. Epub 2008 Jul 25.
Cell shape alterations and accompanying cytoskeletal changes have diverse effects on cell function. We have already shown that dedifferentiated chondrocytes have a round cell morphology and undergo redifferentiation when cultured on chitosan membrane. In the present study, we investigate the role of the cytoskeleton in chondrocyte redifferentiation. Chondrocytes obtained from a micromass culture of chick limb bud mesenchymal cells were subcultured four times. Immunofluorescence analysis of F-actin showed cortical distribution of the actin cytoskeleton upon subculture of dedifferentiated chondrocytes on chitosan membrane. Treatment with cytochalasin D disrupted the cortical actin ring formed during cultivation of chondrocytes on the chitosan membrane, and inhibited chondrocyte redifferentiation. Moreover, cytochalasin D inhibited the phosphorylation of Akt and p38 mitogen activated protein kinase (MAPK), induced during redifferentiation on chitosan membrane. LY294002, an inhibitor of phosphatidylinositol-3-OH-kinase (PI3K), suppressed chondrocyte redifferentiation. These findings suggest that integrity of the actin cytoskeleton is a crucial requirement for PI3K/Akt and p38 MAPK in chondrocyte redifferentiation.
细胞形态改变及伴随的细胞骨架变化对细胞功能具有多种影响。我们已经表明，去分化的软骨细胞具有圆形细胞形态，并且在壳聚糖膜上培养时会经历再分化。在本研究中，我们研究细胞骨架在软骨细胞再分化中的作用。从鸡胚肢芽间充质细胞的微团培养物中获得的软骨细胞传代培养了四次。对F-肌动蛋白的免疫荧光分析表明，去分化的软骨细胞在壳聚糖膜上传代培养时，肌动蛋白细胞骨架呈皮质分布。用细胞松弛素D处理破坏了软骨细胞在壳聚糖膜上培养期间形成的皮质肌动蛋白环，并抑制了软骨细胞的再分化。此外，细胞松弛素D抑制了在壳聚糖膜上再分化过程中诱导的Akt和p38丝裂原活化蛋白激酶（MAPK）的磷酸化。磷脂酰肌醇-3-OH激酶（PI3K）抑制剂LY294002抑制了软骨细胞的再分化。这些发现表明，肌动蛋白细胞骨架的完整性是软骨细胞再分化中PI3K/Akt和p38 MAPK的关键要求。
