Rufy3, a protein specifically expressed in neurons, interacts with actin-bundling protein Fascin to control the growth of axons

Authors

  • Zhe Wei,

    1. Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences/Shanghai JiaoTong University School of Medicine, Shanghai, China
    2. University of Chinese Academy of Sciences, Beijing, China
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    • These authors contributed equally to this work.
  • Ming Sun,

    1. Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences/Shanghai JiaoTong University School of Medicine, Shanghai, China
    2. University of Chinese Academy of Sciences, Beijing, China
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    • These authors contributed equally to this work.
  • Xinyi Liu,

    1. Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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  • Jian Zhang,

    1. Department of Pathophysiology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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  • Ying Jin

    Corresponding author
    1. Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences/Shanghai JiaoTong University School of Medicine, Shanghai, China
    2. Shanghai Stem Cell Institute, Institute of Medical Sciences, Shanghai JiaoTong University School of Medicine, Shanghai, China
    • Address correspondence and reprint requests to Ying Jin, Institute of Health Sciences, 225 South Chongqing Road, Shanghai, 200025, China. E-mail: yjin@sibs.ac.cn

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Abstract

For our nervous system to function properly, each neuron must generate a single axon and elongate the axon to reach its target. It is known that actin filaments and their dynamic interaction with microtubules within growth cones play important roles in inducing axon extension. However, it remains unclear how cytoskeletal dynamics is controlled in growth cones. In this study, we report that Rufy3, a RUN domain-containing protein, is a neuron-specific and actin filament-relevant protein. We find that the appropriate expression of Rufy3 in mouse hippocampal neurons is required for the development of a single axon and axon growth. Our results show that Rufy3 specifically interacts with actin filament-binding proteins, such as Fascin, and colocalizes with Fascin in growth cones. Knockdown of Rufy3 impairs the distribution of Fascin and actin filaments, accompanied by an increased proportion of neurons with multiple axons and a decrease in the axon length. Therefore, Rufy3 may be particularly important for neuronal axon elongation by interacting with Fascin to control actin filament organization in axonal growth cones.

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We propose that Rufy3 may control mouse neuron axon development through its specific interaction with Fascin and Drebrin. Over-expression of Rufy3 (Rufy3 OE) leads to longer axons and expands the distribution of Drebrin to almost the entire growth cone. In contrast, knockdown of Rufy3 (Rufy3 RNAi) results in shortened axons and enhanced the percentage of mutipolar neurons. Moreover, silencing of Rufy3 reduces and restricts the expression of Fascin and F-actin to the edge of the growth cone. These findings provide new insights into the molecular regulation of axonal outgrowth and cell polarization in neurons.

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