How can organs as different as the liver and the brain arise from a single cell in the embryo? Ever since the very first embryonic division cells are able to differentiate into different cell-types, even though their genetic information is essentially identical. The key to this puzzle lies in differentially localizing proteins responsible for the activation of function-specific genes in the two daughter cells, the resulting cells will then have different behaviors. Protein localization is very often essential for development. The question are then, how is localization achieved? Can it be bypassed by some other mechanism?
There is a lot to be learned from localization, and, more interestingly, a lot more to discover. If you are interested in the topic, a good review of the field came out in Nov 09 in Science.
We use Caulobacter crescentus as a model for development; it is a bacterium that lives in fresh water and in its mature form sticks to surfaces through a stalk secreting sticky molecules which turn out to be nature’s strongest glue (that we know of so far). When it divides, the daughter cell does not have a stalk, rather it builds a flagellum that propels it away from its mother. The flagellum is eventually shed and a new stalk is formed (a schematic of the process can be seen above in the bottom right picture). The formation and activation of the flagellum is tightly controlled by proteins, whose localization is both spatially and temporally controlled. Changing the localization gives rise to mutant cells but that can be sometimes rescued by varying other parameters. We are investigating computationally how changes in localization in the key proteins involved in this process might give rise to different phenotypes.
