Figure 3

Inhibition of actin polymerization induces Atf3 expression through transcriptional mechanisms. A) Primary chondrocytes were cultured for 24 hours with DMSO (control) or 1 μM cytochalasin D before harvest and RNA isolation. Real-time PCR demonstrated marked induction of Atf3 mRNA levels by cytochalasin D. Data represent averages and SEM from three independent experiments, normalized to Gapdh (*: p < 0.05). B) Primary chondrocytes were transfected with an Atf3 promoter plasmid and pRLCMV, followed by incubation for 24 hours with DMSO (control) or 1 μM cytochalasin D. Cells were then harvested, firefly luciferase activity was measured and normalized to Renilla luciferase activity. Data represent averages and SEM from three independent experiments, performed in quadruplicate each (*: p < 0.05). Cytochalasin D induced Atf3 promoter activity.