Understanding PP2A phosphatase function in the early C. elegans embryo

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When cells divide, a multitude of processes must occur at the correct time and in the correct manner. One way that cells orchestrate events required for cell division is by turning on or off the individual components used to accomplish different tasks. Such switches in protein activity can be accomplished by modifying the proteins after they are made. One of the most common ways to modify protein function is through the addition or removal of a phosphate group to the protein. Specific enzymes are used for this: kinases add phosphate groups and phosphatases remove them. These two classes of enzymes are extremely important for the regulation of all cellular processes. There are hundreds of different kinases and phosphatases, and each one can perform very specific roles. We study a phosphatase that is implicated in regulating the assembly and function of a structure that forms only when cells divide. This structure, the mitotic spindle, is used to physically pull chromosomes apart and place them into the future daughter cells as the cell divides. The mitotic spindle consists of, among other components, long rigid fibres called microtubules. The phosphatase we study controls the formation of these fibres and it is essential for proper mitotic spindle assembly. To understand how this phosphatase functions, we will use a combined genetics and biochemical approach to identify any proteins that might regulate its activity, as well as any proteins that the phosphatase directly controls. This phosphatase is also involved in other cellular processes, and we and interested in determining how it can perform multiple tasks at the same time, in the same cell. In order to study the behaviour of the phosphatase in living cells, we are developing innovative microscopy approaches to track the dynamic movement of the phosphatase enzyme as it performs its normal functions. This work will help us understand how cells regulate microtubule fibres to build complex three-dimensional structures such as the mitotic spindle.