The novel GTPase Rit differentially regulates axonal and dendritic growth

Pamela J Lein, Xin Guo, Geng Xian Shi, Melissa Moholt-Siebert, Donald Bruun, Douglas A. Andres

Research output: Contribution to journalArticle

42 Scopus citations

Abstract

The Rit GTPase is widely expressed in developing and adult nervous systems, and our previous data with pheochromocytoma cells implicate Rit signaling in NGF-induced neurite outgrowth. In this study, we investigated a role for Rit in neuronal morphogenesis. Expression of a dominant-negative (dn) Rit mutant in hippocampal neurons inhibited axonal growth but potentiated dendritic growth. Conversely, a constitutively active (ca) Rit mutant promoted axonal growth but inhibited dendritic growth. Dendritogenesis is regulated differently in sympathetic neurons versus hippocampal neurons in that sympathetic neurons require NGF and bone morphogenetic proteins (BMPs) to trigger dendritic growth. Despite these differences, dnRit potentiated and caRit blocked BMP7-induced dendritic growth in sympathetic neurons. Biochemical studies indicated that BMP7 treatments that caused dendritic growth also decreased Rit GTP loading. Additional studies demonstrate that caRit increased extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation and pharmacological inhibition of MEK1 (mitogen-activated protein kinase/ERK 1) blocked the axon-promoting and dendrite-inhibiting effects of caRit. These observations suggest that Rit is a convergence point for multiple signaling pathways and it functions to promote axonal growth but inhibit dendritic growth via activation of ERK1/2. Modulation of the activational status of Rit may therefore represent a generalized mechanism across divergent neuronal cell types for regulating axonal versus dendritic growth modes.

Original languageEnglish (US)
Pages (from-to)4725-4736
Number of pages12
JournalJournal of Neuroscience
Volume27
Issue number17
DOIs
StatePublished - Apr 25 2007
Externally publishedYes

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Keywords

  • Axon
  • BMP
  • Dendrite
  • ERK
  • GTPase
  • Hippocampal neuron
  • NGF
  • Rit
  • Sympathetic neuron

ASJC Scopus subject areas

  • Neuroscience(all)

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