Examining the function of TPX2 during neurite morphogenesis (727.2)

Abstract

A functional nervous system depends on the intricate connections between neurons. To establish appropriate connections between neurons, the morphogenetic process of the neuron must be carefully regulated. Neuritogenesis is the morphogenetic process that regulates neurite extension and connection. It has been shown that the microtubule cytoskeleton and microtubule‐associated proteins are indispensable for this process. The microtubule‐associated protein, targeting protein for Xklp2 (TPX2) plays critical roles during mitosis. TPX2 is required to generate a stable bipolar spindle. It localizes to the nucleus during interphase and to the spindle poles during mitosis. We previously identified TPX2 as one of the most abundant proteins on neuronal microtubules, suggesting that TPX2 may play a role during neuritogensis. To examine the function of TPX2 in neurons, we depleted TPX2 in mouse primary hippocampal neurons using shRNA and observed a decrease in neurite length and branching number, suggesting TPX2 is involved in the neurite elongation and branching process. To determine the mechanistic basis of TPX2 on these processes, we examined the localization of TPX2 in hippocampal neurons. We observed that TPX2 localized primarily to the centrosome and interacted with gamma‐tubulin. Additionally, TPX2 also distributed in the neurites and bound to the microtubule cytoskeleton. To determine how TPX2 affects the microtubule cytoskeleton, we analyzed the dynamics of microtubules in TPX2‐depleted neurons by examining the microtubule plus‐end binding protein EB3. However, we did not observe any change in microtubule plus‐end dynamics or microtubule emanating frequency in TPX2‐depleted neurons. These results indicate that TPX2 participates in the neuritogenesis process and may exert its effect via neurite‐localized and microtubule‐bound population.Grant Funding Source: Supported by National Science Council of Taiwan