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[Abstract Title]. - Society for Neuroscience

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231. Dendrite Growth and Branching: Signaling<br />

Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm<br />

Program#/Poster#: 231.7/B20<br />

Topic: A.04.i. Dendritic growth and branching<br />

Support: Scientific Research from the Ministry of Education, Science, Sports, and Culture of<br />

Japan<br />

the Takeda Science Foundation<br />

<strong>Title</strong>: Regulation of dendritic development by the Rac activator Dock4 in hippocampal neurons<br />

Authors: *H. KATOH, S. UEDA, S. FUJIMOTO, M. NEGISHI;<br />

Lab. Mol Neurobiol Grad Sch. Biostudies, Kyoto Univ., Kyoto, Japan<br />

<strong>Abstract</strong>: Dendrite development is required <strong>for</strong> establishing proper neuronal connectivity. It is<br />

already well known that members of the Rho family small GTPases are key regulators of the<br />

actin cytoskeleton in diverse cellular functions including neuronal morphogenesis However, the<br />

molecular mechanisms that control the activities of Rho GTPases in developing dendrites are not<br />

well understood. Dock4 is a member of an evolutionarily conserved superfamily of Dock180related<br />

proteins and functions as a guanine nucleotide exchange factor (GEF) <strong>for</strong> the small<br />

GTPase Rac. We found that Dock4 is highly expressed in the developing rat brain,<br />

predominantly in the hippocampal neurons. In dissociated cultured hippocampal neurons, the<br />

level of Dock4 protein is up-regulated between 3 and 8 days in culture, when dendrites begin to<br />

grow. Knockdown of endogenous Dock4 results in reduced dendritic growth and branching.<br />

Conversely, overexpression of Dock4 with its binding partner ELMO2 enhances the numbers of<br />

dendrites and dendritic branches. These morphological effects elicited by Dock4 and ELMO2<br />

require the Rac activation and the C-terminal region of Dock4. These findings demonstrate a<br />

new function of the Rac activator Dock4 in dendritic morphogenesis in hippocampal neurons.<br />

Disclosures: H. Katoh , None; S. Ueda, None; S. Fujimoto, None; M. Negishi, None.<br />

Poster<br />

231. Dendrite Growth and Branching: Signaling<br />

Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm<br />

Program#/Poster#: 231.8/B21

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