A single tyrosine phosphorylation site in cortactin is important for filopodia formation in neuronal growth cones

Cortactin is a Src tyrosine phosphorylation substrate that regulates multiple actin-related cellular processes. While frequently studied in nonneuronal cells, the functions of cortactin in neuronal growth cones are not well understood. We recently reported that cortactin mediates the effects of Src...

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Bibliographic Details
Published in:Molecular biology of the cell 2019-07, Vol.30 (15), p.1817-1833
Main Authors: Ren, Yuan, He, Yingpei, Brown, Sherlene, Zbornik, Erica, Mlodzianoski, Michael J, Ma, Donghan, Huang, Fang, Mattoo, Seema, Suter, Daniel M
Format: Article
Language:English
Subjects:
Actin-Related Protein 2-3 Complex - metabolism
Animals
Aplysia - metabolism
Cell Membrane - metabolism
Cortactin - metabolism
Growth Cones - metabolism
Neurons - metabolism
Phosphorylation
Phosphotyrosine - metabolism
Pseudopodia - metabolism
Recombinant Proteins - metabolism
Signal Transduction
src-Family Kinases - metabolism
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Summary:Cortactin is a Src tyrosine phosphorylation substrate that regulates multiple actin-related cellular processes. While frequently studied in nonneuronal cells, the functions of cortactin in neuronal growth cones are not well understood. We recently reported that cortactin mediates the effects of Src tyrosine kinase in regulating actin organization and dynamics in both lamellipodia and filopodia of growth cones. Here, we identified a single cortactin tyrosine phosphorylation site (Y499) to be important for the formation of filopodia. Overexpression of a 499F phospho-deficient cortactin mutant decreased filopodia length and density, whereas overexpression of a 499E phospho-mimetic mutant increased filopodia length. Using an antibody against cortactin pY499, we showed that tyrosine-phosphorylated cortactin is enriched along the leading edge. The leading edge localization of phosphorylated cortactin is Src2-dependent, F-actin-independent, and important for filopodia formation. In vitro kinase assays revealed that Src2 phosphorylates cortactin at Y499, although Y505 is the preferred site in vitro. Finally, we provide evidence that Arp2/3 complex acts downstream of phosphorylated cortactin to regulate density but not length of filopodia. In conclusion, we have characterized a tyrosine phosphorylation site in cortactin that plays a major role in the Src/cortactin/Arp2/3 signaling pathway controlling filopodia formation.
ISSN:1059-1524
1939-4586
DOI:10.1091/mbc.E18-04-0202