November 3, 2011

I love a hidden picture task. I love looking at a picture of a crowded street scene and identifying the nerd in the red and white sweater (side note: would Waldo’s fashion choices put him in the hipster category these days?). In cell biology, a researcher has to sort through the crowded scene in a cell to find what he or she is looking for. Today’s image is from a paper describing the function of microtubule motors, a difficult job given the complexity and interdependence of the motors and their regulators.

Microtubule motors called dynein and kinesin move all sorts of material around the cell. The motor binds to its cargo, a membrane vesicle for example, and “walks” it along a microtubule until it reaches its destination, such as an endosome or lysosome in this example. With multiple motors in any given cell type and a slew of regulators for each, the understanding of an individual motor’s contribution is unclear. A recent paper helps to sort through this complexity. In this paper, Yi and colleagues used acute inhibition of dynein and its regulators, followed by precise tracking of particles in a cell. Following the inhibition of dynein, multiple cargoes rapidly disperse around the cell, suggesting a sharp drop in minus-end directed transport along microtubules. In the images above, the top row shows cells at the time of the dynein inhibition, while bottom row shows several minutes later. Lysosomes/late endosomes, early endosomes, Golgi, and injected adenovirus (left to right) all dispersed towards the cell periphery following dynein inhibition. Interestingly, Yi and colleagues also saw a gradual decrease in transport in the other direction (plus-end directed) following dynein inhibition, suggesting a possible global effect on transport.

Yi, J., Ori-McKenney, K., McKenney, R., Vershinin, M., Gross, S., & Vallee, R. (2011). High-resolution imaging reveals indirect coordination of opposite motors and a role for LIS1 in high-load axonal transport originally published in The Journal of Cell Biology, 195 (2), 193-201 DOI: 10.1083/jcb.201104076