Integrity of the cortical actin ring is required for activation of the PI3K/Akt and p38 MAPK signaling pathways in redifferentiation of chondrocytes on chitosan.
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.
Park
Eun Hee
EH
Department of Biology, College of Natural Sciences, Kyungpook National University, 1370 Sankyuck-dong, Buk-gu, Daegu 702-701, South Korea.
Kang
Shin-Sung
SS
Lee
Young-Sup
YS
Kim
Song-Ja
SJ
Jin
Eun-Jung
EJ
Tak
Eun Nam
EN
Sonn
Jong Kyung
JK
D000199:Actins / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D048430:Cell Shape; D002478:Cells, Cultured; D002642:Chick Embryo; D048271:Chitosan / Q000378:metabolism*; D019902:Chondrocytes / Q000166:cytology / Q000502:physiology; D015638:Cytochalasin D / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000502:physiology*; D019384:Nucleic Acid Synthesis Inhibitors / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
D000199:Actins; D004791:Enzyme Inhibitors; D019384:Nucleic Acid Synthesis Inhibitors; D015638:Cytochalasin D; D048271:Chitosan; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D048051:p38 Mitogen-Activated Protein Kinases