Dok-4 regulates GDNF-dependent neurite outgrowth through downstream activation of Rap1 and mitogen-activated protein kinase

Mayumi Uchida, Atsushi Enomoto, Toshifumi Fukuda, Kel Kurokawa, Kengo Maeda, Yoshinori Kodama, Naoya Asai, Taisaku Hasegawa, Yohei Shimono, Mayumi Jijiwa, Masatoshi Ichichara, Yoshiki Murakumo, Masahide Takahashi

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)

Abstract

During development of the central and peripheral nervous systems, neurite extension mediated via gfial-cell-line- Us 11 derived neurotrophic factor (GDNF) and its receptor RET is critical for neuronal differentiation. In the present study, we investigated the role of the RET substrate Dok-4 in neurite outgrowth induced by the GDNF/RET signaling pathway. In TGW neuroblastoma cells, which endogenously express both RET and Dok-4, depletion of Dok-4 through treatment with small interfering RNA resulted in a marked decrease in GDNF-stimulated neurite outgrowth. By contrast, exogenous expression of wild-type Dok-4 induced sustained p44/42 n-dtogen-activated protein kinase (ERK1/2) activation and enhanced neurite outgrowth. Expression of Dok-4 mutants in which the tyrosine residues at codons 187, 220 and 270, conserved between Dok-4, -5, and -6, were each replaced with a phenylalanine inhibited sustained ERKI/2 activation and neurite outgrowth. We also found that Dok-4 induced a significant activation of the small G protein Rap1 and that expression of a dominant active Rapl mutant restored neurite outgrowth in Dok-4-depleted cells. By contrast, expression of a dominant negative Rap1 mutant impaired GDNF-stimulated neurite outgrowth from TGW cells. Finally, we found that neurite formation in cultured rat hippocampal neurons was enhanced by the expression of Dok-4. Together, our results suggest that Dok-4, through activation of the Rap1-ERK1/2 pathway, regulates GDNF- mediated neurite outgrowth during neuronal development.

Original languageEnglish
Pages (from-to)3067-3077
Number of pages11
JournalJournal of cell science
Volume119
Issue number15
DOIs
Publication statusPublished - 01-08-2006
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Cell Biology

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