Investigating the control mechanisms of centrosome organization

Abstract

Centrosome is one major type of microtubule organizing center in animal cells localizing on the microtubule minus ends. Centrosome regulates the nucleation of microtubules, anchoring of the polymerized microtubules and it duplicates only once in one cell cycle. End binding protein 1 (EB1), on the other hand, is an important protein localized on the microtubule plus ends, recruiting other plus tip interacting proteins to function in cytoskeleton regulation. Recent studies show that EB1 is also a steady component of centrosomes while the actual function of centrosomal EB1 is yet to be clearly defined. In this study, I aim at generating a comprehensive map of EB1 protein interactions and investigating the mechanisms by which its binding proteins are involved in centrosome organization. I performed a genome wide prediction for new EB1 binding proteins and verified at least four new EB1 interacting proteins. One EB1 binding protein GAS2L1, positioning on the centriole proximal ends, was required for centrosome separation in G2, which is the prerequisite for bipolar spindle formation. My research suggests that GAS2L1 involved centrosome separation depends on an intact cytoskeleton network, both actins and microtubules, and EB1 association. The activity of GAS2L1 is regulated in a cell cycle dependent manner. After mitosis, centrosomes would recruit new PCM proteins onto them. Another EB1 binding protein, CDK5RAP2, has been found to act as a scaffold for anchoring other PCM components like γ-tubulin ring complex. In my study, the mechanism of how CDK5RAP2 can act highly dynamically on centrosomes is revealed and I show a dynein-dynactin based transportation is critical for CDK5RAP2 centrosomal recruitment. My research on these EB1 related centrosome proteins elucidates the importance of their functions on regulating the centrosome organization and also suggests potential role of EB1 on the centrosome.

Date of Award	2013
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology