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

J Neurochem. 2014 Sep;130(5):678-92. doi: 10.1111/jnc.12740. Epub 2014 May 19.

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. 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.

Keywords: F-actin; Fascin; Rufy3; axon length; growth cones.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Axons / metabolism
  • Blotting, Western
  • Carrier Proteins / metabolism*
  • Cells, Cultured
  • Fluorescent Antibody Technique
  • Growth Cones / metabolism*
  • HEK293 Cells
  • Humans
  • Immunoprecipitation
  • Mass Spectrometry
  • Mice
  • Mice, Inbred C57BL
  • Microfilament Proteins / metabolism*
  • Nerve Tissue Proteins / metabolism*
  • Neurogenesis / physiology*
  • Neurons / metabolism
  • Neuropeptides / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transfection

Substances

  • Carrier Proteins
  • Microfilament Proteins
  • Nerve Tissue Proteins
  • Neuropeptides
  • Rufy3 protein, mouse
  • drebrins
  • fascin