During brain development, neural precursor cells migrate along radial glial fibers to populate the neocortex. RNA interference (RNAi) of the lissencephaly gene LIS1 (also known as PAFAH1b1) inhibits somal movement but not process extension of neural precursors in live brain slices. Here we report imaging of the subcellular events accompanying neural precursor migration and the effects of LIS1, cytoplasmic dynein and myosin II inhibition. Centrosomes move continuously and often far in advance of nuclei, which show extreme saltatory behavior. LIS1 and dynein RNAi inhibit centrosomal and nuclear movement independently, whereas myosin II inhibition blocks only nuclear translocation. Imaging of the microtubule end-binding protein 3 (EB3) reveals a centrosome-centered array of microtubules in live neural precursors under all conditions examined. Dynein is concentrated both at a swelling in the leading process reported to initiate each migratory cycle and in the soma. Thus, dynein pulls on the microtubule network from the swelling. The nucleus is transported along the trailing microtubules by dynein assisted by myosin II.

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SUMMARY Early in infection, adenovirus travels to the nucleus as a naked capsid using the microtubule motor cytoplasmic dynein. This study was initiated to address how the virus recruits dynein, and to explore the role of dynein's diverse regulatory factors in virus transport. Cytoplasmic dynein, dynactin and NudE/NudEL, but not LIS1 or ZW10, colocalized with incoming, post-endosomal adenovirus particles. Dynein alone interacted in a pH-dependent manner with the adenovirus subunit hexon, which, in turn, interacted with recombinant dynein intermediate chain and light intermediate chain 1. Interference with dynactin function had no effect on dynein colocalization with adenovirus, but reduced virus run length. Expression of hexon or injection of anti-hexon antibody inhibited virus transport without affecting Golgi distribution. These results identify hexon as a direct receptor for cytoplasmic dynein, which recruits dynein for transport to the nucleus by a mechanism both novel and distinct from that for known physiological dynein cargo forms.

These results demonstrate that lipid-mediated activation of RPC-based polyplexes is a useful strategy to enhance intracellular delivery of nucleic acids and potentiate therapeutic activity.