Abstract
Actin cytoskeleton has been known to control and/or be associated with chondrogenesis. Staurosporine and cytochalasin D modulate actin cytoskeleton and affect chondrogenesis. However, the underlying mechanisms for actin dynamics regulation by these agents are not known well. In the present study, we investigate the effect of staurosporine and cytochalasin D on the actin dynamics as well as possible regulatory mechanisms of actin cytoskeleton modulation. Staurosporine and cytochalasin D have different effects on actin stress fibers in that staurosporine dissolved actin stress fibers while cytochalasin D disrupted them in both stress forming cells and stress fiber-formed cells. Increase in the G-/F-actin ratio either by dissolution or disruption of actin stress fiber is critical for the chondrogenic differentiation. Cytochalasin D reduced the phosphorylation of cofilin, whereas staurosporine showed little effect on cofilin phosphorylation. Either staurosporine or cytochalasin D had little effect on the phosphorylation of myosin light chain. These results suggest that staurosporine and cytochalasin D employ different mechanisms for the regulation of actin dynamics and provide evidence that removal of actin stress fibers is crucial for the chondrogenic differentiation.
Highlights
Dynamic actin cytoskeleton is essential for diverse cellular processes such as the driving cell shape changes, cellular motility, adhesion, cytokinesis, and endocytosis (Pollard and Cooper, 2009)
Staurosporine and cytochalasin D have different effect on the phosphorylation of cofilin To find the factors which regulate actin dynamics during chondrogenesis induction, we examined whether the two drugs influence the phosphorylation of cofilin
We employed two different drugs which modulate actin filaments and com pared their effects on chondrogenesis, F-/globular actin (G-actin) ratio, and phosphorylation of cofilin and myosin light chain (MLC)
Summary
Dynamic actin cytoskeleton is essential for diverse cellular processes such as the driving cell shape changes, cellular motility, adhesion, cytokinesis, and endocytosis (Pollard and Cooper, 2009). Cellular condensation during which cell shape change occurs is a complicated process that are regulated by multiple cellular signaling molecules (DeLise et al, 2000) and it could be hard to explore the mechanisms of cell shape changes and the role of cell shape and/or cytoskeleton in the chondrogenesis using micromass culture system. Single cell culture systems would provide good models for the study of role of cell shape and/or cytoskeleton in chondrogenesis. Chondrogenesis is induced in single cell culture systems such as suspension culture (Solursh et al, 1982) and three-dimensional culture systems using polymers, hydrogels or micromass culture
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
