Temporally and spatially coordinated roles for Rho, Rac, Cdc42 and their effectors in growth cone guidance by a physiological electric field.

Research output: Contribution to journalArticle

67 Citations (Scopus)

Abstract

Although it is known that neuronal growth cones migrate towards the cathode of an applied direct current ( DC) electric field (EF), resembling the EF present in the developing nervous system, the underlying mechanism remains unclear. Here, we demonstrate temporally and spatially coordinated roles for the GTPases Rac, Cdc42 and Rho and their effectors. Growth cones of cultured Xenopus embryonic spinal neurons turned towards the cathode but collective inhibition of Rho, Rac and Cdc42 attenuated turning. Selective inhibition of Rho, Cdc42 or Rac signalling revealed temporally distinct roles in steering by an electrical gradient. Rho, Rac and Cdc42 are each essential for turning within the initial 2 hours (early phase). Later, Rho and Cdc42 signals remain important but Rac signalling dominates. The EF increased Rho immunofluorescence anodally. This correlated spatially with collapsed growth cone morphology and reduced anodal migration rates, which were restored by Rho inhibition. These data suggest that anodally increased Rho activity induces local cytoskeletal collapse, biasing growth cone advance cathodally. Collapse might be mediated by the Rho effectors p160 Rho kinase and myosin light chain kinase since their inhibition attenuated early turning. Inhibitors of phosphoinositide 3-kinase, MEK1/2 or p38 mitogen-activated protein kinase (MAPK) did not affect turning behaviour, eliminating them mechanistically. We propose a mechanism whereby Rac and Cdc42 activities dominate cathodally and Rho activity dominates anodally to steer growth cones towards the cathode. The interaction between Rho GTPases, the cytoskeleton and growth cone dynamics is explored in the companion paper published in this issue. Our results complement studies of growth cone guidance by diffusible chemical gradients and suggest that growth cones might interpret these co-existing guidance cues selectively.

Original languageEnglish
Pages (from-to)1723-1735
Number of pages12
JournalJournal of Cell Science
Volume119
DOIs
Publication statusPublished - Apr 2006

Keywords

  • axon guidance
  • electric field
  • Rho GTPases
  • SPINAL-CORD-INJURY
  • MEDIATING AXON GUIDANCE
  • NERVE GROWTH
  • FAMILY GTPASES
  • LYSOPHOSPHATIDIC ACID
  • SIGNALING PATHWAYS
  • DIRECTED GROWTH
  • NEURITE GROWTH
  • CELL-MIGRATION
  • PROTEIN-KINASE

Cite this

@article{27f13bc26c5d4a3d8cf20a7bfe8d8ba6,
title = "Temporally and spatially coordinated roles for Rho, Rac, Cdc42 and their effectors in growth cone guidance by a physiological electric field.",
abstract = "Although it is known that neuronal growth cones migrate towards the cathode of an applied direct current ( DC) electric field (EF), resembling the EF present in the developing nervous system, the underlying mechanism remains unclear. Here, we demonstrate temporally and spatially coordinated roles for the GTPases Rac, Cdc42 and Rho and their effectors. Growth cones of cultured Xenopus embryonic spinal neurons turned towards the cathode but collective inhibition of Rho, Rac and Cdc42 attenuated turning. Selective inhibition of Rho, Cdc42 or Rac signalling revealed temporally distinct roles in steering by an electrical gradient. Rho, Rac and Cdc42 are each essential for turning within the initial 2 hours (early phase). Later, Rho and Cdc42 signals remain important but Rac signalling dominates. The EF increased Rho immunofluorescence anodally. This correlated spatially with collapsed growth cone morphology and reduced anodal migration rates, which were restored by Rho inhibition. These data suggest that anodally increased Rho activity induces local cytoskeletal collapse, biasing growth cone advance cathodally. Collapse might be mediated by the Rho effectors p160 Rho kinase and myosin light chain kinase since their inhibition attenuated early turning. Inhibitors of phosphoinositide 3-kinase, MEK1/2 or p38 mitogen-activated protein kinase (MAPK) did not affect turning behaviour, eliminating them mechanistically. We propose a mechanism whereby Rac and Cdc42 activities dominate cathodally and Rho activity dominates anodally to steer growth cones towards the cathode. The interaction between Rho GTPases, the cytoskeleton and growth cone dynamics is explored in the companion paper published in this issue. Our results complement studies of growth cone guidance by diffusible chemical gradients and suggest that growth cones might interpret these co-existing guidance cues selectively.",
keywords = "axon guidance, electric field, Rho GTPases, SPINAL-CORD-INJURY, MEDIATING AXON GUIDANCE, NERVE GROWTH, FAMILY GTPASES, LYSOPHOSPHATIDIC ACID, SIGNALING PATHWAYS, DIRECTED GROWTH, NEURITE GROWTH, CELL-MIGRATION, PROTEIN-KINASE",
author = "Rajnicek, {Ann Marie} and Foubister, {L. E.} and McCaig, {Colin Darnley}",
year = "2006",
month = "4",
doi = "10.1242/jcs.02896",
language = "English",
volume = "119",
pages = "1723--1735",
journal = "Journal of Cell Science",
issn = "0021-9533",
publisher = "Company of Biologists Ltd",

}

TY - JOUR

T1 - Temporally and spatially coordinated roles for Rho, Rac, Cdc42 and their effectors in growth cone guidance by a physiological electric field.

AU - Rajnicek, Ann Marie

AU - Foubister, L. E.

AU - McCaig, Colin Darnley

PY - 2006/4

Y1 - 2006/4

N2 - Although it is known that neuronal growth cones migrate towards the cathode of an applied direct current ( DC) electric field (EF), resembling the EF present in the developing nervous system, the underlying mechanism remains unclear. Here, we demonstrate temporally and spatially coordinated roles for the GTPases Rac, Cdc42 and Rho and their effectors. Growth cones of cultured Xenopus embryonic spinal neurons turned towards the cathode but collective inhibition of Rho, Rac and Cdc42 attenuated turning. Selective inhibition of Rho, Cdc42 or Rac signalling revealed temporally distinct roles in steering by an electrical gradient. Rho, Rac and Cdc42 are each essential for turning within the initial 2 hours (early phase). Later, Rho and Cdc42 signals remain important but Rac signalling dominates. The EF increased Rho immunofluorescence anodally. This correlated spatially with collapsed growth cone morphology and reduced anodal migration rates, which were restored by Rho inhibition. These data suggest that anodally increased Rho activity induces local cytoskeletal collapse, biasing growth cone advance cathodally. Collapse might be mediated by the Rho effectors p160 Rho kinase and myosin light chain kinase since their inhibition attenuated early turning. Inhibitors of phosphoinositide 3-kinase, MEK1/2 or p38 mitogen-activated protein kinase (MAPK) did not affect turning behaviour, eliminating them mechanistically. We propose a mechanism whereby Rac and Cdc42 activities dominate cathodally and Rho activity dominates anodally to steer growth cones towards the cathode. The interaction between Rho GTPases, the cytoskeleton and growth cone dynamics is explored in the companion paper published in this issue. Our results complement studies of growth cone guidance by diffusible chemical gradients and suggest that growth cones might interpret these co-existing guidance cues selectively.

AB - Although it is known that neuronal growth cones migrate towards the cathode of an applied direct current ( DC) electric field (EF), resembling the EF present in the developing nervous system, the underlying mechanism remains unclear. Here, we demonstrate temporally and spatially coordinated roles for the GTPases Rac, Cdc42 and Rho and their effectors. Growth cones of cultured Xenopus embryonic spinal neurons turned towards the cathode but collective inhibition of Rho, Rac and Cdc42 attenuated turning. Selective inhibition of Rho, Cdc42 or Rac signalling revealed temporally distinct roles in steering by an electrical gradient. Rho, Rac and Cdc42 are each essential for turning within the initial 2 hours (early phase). Later, Rho and Cdc42 signals remain important but Rac signalling dominates. The EF increased Rho immunofluorescence anodally. This correlated spatially with collapsed growth cone morphology and reduced anodal migration rates, which were restored by Rho inhibition. These data suggest that anodally increased Rho activity induces local cytoskeletal collapse, biasing growth cone advance cathodally. Collapse might be mediated by the Rho effectors p160 Rho kinase and myosin light chain kinase since their inhibition attenuated early turning. Inhibitors of phosphoinositide 3-kinase, MEK1/2 or p38 mitogen-activated protein kinase (MAPK) did not affect turning behaviour, eliminating them mechanistically. We propose a mechanism whereby Rac and Cdc42 activities dominate cathodally and Rho activity dominates anodally to steer growth cones towards the cathode. The interaction between Rho GTPases, the cytoskeleton and growth cone dynamics is explored in the companion paper published in this issue. Our results complement studies of growth cone guidance by diffusible chemical gradients and suggest that growth cones might interpret these co-existing guidance cues selectively.

KW - axon guidance

KW - electric field

KW - Rho GTPases

KW - SPINAL-CORD-INJURY

KW - MEDIATING AXON GUIDANCE

KW - NERVE GROWTH

KW - FAMILY GTPASES

KW - LYSOPHOSPHATIDIC ACID

KW - SIGNALING PATHWAYS

KW - DIRECTED GROWTH

KW - NEURITE GROWTH

KW - CELL-MIGRATION

KW - PROTEIN-KINASE

U2 - 10.1242/jcs.02896

DO - 10.1242/jcs.02896

M3 - Article

VL - 119

SP - 1723

EP - 1735

JO - Journal of Cell Science

JF - Journal of Cell Science

SN - 0021-9533

ER -