Light chain 3 associates with a Sos1 guanine nucleotide exchange factor: Its significance in the Sos1-mediated Rac1 signaling leading to membrane ruffling

Shuichi Furuta, Koichi Miura, Terry Copeland, Wei Hao Shang, Aki Oshima, Tohru Kamata

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

A 19 kDa protein was identified to associate with the Dbl oncogene homology domain of Sos1 (Sos-DH) and was purified from rat brains by GST-Sos-DH affinity chromatography. Peptide sequencing revealed that the protein is identical to light chain 3 (LC3), a microtubule-associated protein. LC3 coimmunoprecipitated with Sos1, and GST-LC3 was capable of forming complexes with Sos1 in in vitro GST-pull down assay. Furthermore, LC3 was colocalized with Sos1 in cells, as determined by immunohistochemistry. While Sos1 stimulated the guanine nucleotide exchange reaction on Rac1, LC3 suppressed the ability of Sos1 to activate Rac1 in in vitro experiments using COS cell lysates. Consistent with this, overexpression of LC3 decreased the level of active GTP-bound Rac1 in COS cells. Sos1 expression induced membrane ruffling, a downstream target for Rac1, but LC3 expression inhibited this biological effect of Sos1. These findings suggest that LC3 interacts with Sos1 and thereby negatively regulates the Sos1-dependent Rac1 activation leading to membrane ruffling.

Original languageEnglish
Pages (from-to)7060-7066
Number of pages7
JournalOncogene
Volume21
Issue number46
DOIs
Publication statusPublished - 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Genetics
  • Cancer Research

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