engleski

The Role of Arp2/3 in DRG Growth Cones Motility

The Arp2/3 complex simultaneously controls nucleation of actin polymerization and filament branching. We used optical tweezers and video imaging to analyse the role of Arp2/3 in the motility of lamellipodia from developing growth cones (GCs) of isolated Dorsal Root Ganglia (DRG) neurons. Kymograph analysis shows that inhibition of Arp 2/3 complex with 100 µM CK548 completely abolished the lamellipodia motion. Surprisingly when the activity of Arp2/3 is inhibited by 25 µM CK548, lamellipodia shrank for 6-8 min but then reappears again and show an almost normal motility. The average period to complete protrusion and retraction cycles of lamellipodia 76 s in control, increased to 110 s after the recovery from the exposure to this drug. The drug CK548 decreased, initially, the ability of the lamellipodia to lift up in the axial direction, but after the recovery lamellipodia were able to lift 4 µm up above the coverslip as in control conditions. The force generated by lamellipodia and their maximal protrusion velocity decreased when the concentration of drug CK548 is increased from 25 to 100 µM. After the recovery of an almost normal motility, ruffles were present but had a different shape and were more fragmented and invaginated, suggesting an altered cytoskeleton. These results show that Arp 2/3 is important in maintaining the morphology and the motility of the neuronal growth cones but in neuronal lamellipodia several distinct pathways contribute to actin filament branching and to their cross-linkage.

growth cones ; optical tweezers

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