Volume 7 issue 10 October 2006
Antagonistic forces generated by cytoplasmic dynein and myosin-II during growth cone turning and axonal retraction
Kenneth A. Myers, Irina Tint, C. Vidya Nadar, Yan He, Mark M. Black, Peter W. Baas

Supplementary information

Movie 1: Legend: Control siRNA-treated growth cone of a rat sympathetic neuron transfected with EGFP-EB3. The EB3 comets emanating from the central zone of the growth cone are observed to consistently enter growth cone filopodia and progress toward their distal tips. The frames were acquired every 1 second for 3 minutes

Movie 1 (.mov)

Movie 2: Legend: Dynein-depleted growth cone of a rat sympathetic neuron transfected with EGFP-EB3. Unlike the control growth cone, not many comets progress outward from the central zone. A few EB3 comets can be seen in the peripheral zone but are unable to gain entrance into filopodia. Shown particularly well in this movie is the retrograde flow of actin, which may be representative of myosin-II-driven forces manifested in the absence of dynein-based oppositional forces. The frames were acquired every 1 second for 3 minutes.

Movie 2 (.mov)

Movie 3: Legend: Dynein-depleted growth cone of a rat sympathetic neuron transfected with mRFP-EB3 and treated with 0.1% DMSO for 10 minutes. The comets are seen only in the central zone and are unable to invade filopodia, reminiscent of EGFP-EB3 comets under conditions of dynein depletion (see Movie II). The frames were acquired every 1 second for 2 minutes.

Movie 3 (.mov)

Movie 4: Legend: Dynein-depleted growth cone of a rat sympathetic neuron treated with 50uM blebbistatin for 10 minutes to inhibit the activity of myosin-II. Seen here, comets arise in the central region of the growth cone and consistently invade filopodia, progressing toward the distal tips of filopodia in a manner similar to neurons treated with control siRNA alone (see Movie I). These data support the hypothesis that the inhibition of myosin-II serves to relieve dynein-based inhibition of microtubule invasion of filopodia. The frames were acquired every 1 second for 2 minutes.

Movie 4 (.mov)