TGF-β-induced cell motility requires downregulation of ARHGAPs to sustain Rac1 activity

Mitsuyoshi Motizuki; Daizo Koinuma; Takashi Yokoyama; Yuka Itoh; Chiho Omata; Kohei Miyazono; Masao Saitoh; Keiji Miyazawa

doi:10.1016/j.jbc.2021.100545

TGF-β-induced cell motility requires downregulation of ARHGAPs to sustain Rac1 activity

J Biol Chem. 2021 Jan-Jun:296:100545. doi: 10.1016/j.jbc.2021.100545. Epub 2021 Mar 17.

Authors

Mitsuyoshi Motizuki¹, Daizo Koinuma², Takashi Yokoyama¹, Yuka Itoh¹, Chiho Omata¹, Kohei Miyazono², Masao Saitoh³, Keiji Miyazawa⁴

Affiliations

¹ Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan.
² Department of Molecular Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
³ Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan; Center for Medical Education and Science, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan.
⁴ Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan. Electronic address: kmiyazawa@yamanashi.ac.jp.

Abstract

Transforming growth factor-β (TGF-β) signaling promotes cancer progression. In particular, the epithelial-mesenchymal transition (EMT) induced by TGF-β is considered crucial to the malignant phenotype of cancer cells. Here, we report that the EMT-associated cellular responses induced by TGF-β are mediated by distinct signaling pathways that diverge at Smad3. By expressing chimeric Smad1/Smad3 proteins in SMAD3 knockout A549 cells, we found that the β4 region in the Smad3 MH1 domain is essential for TGF-β-induced cell motility, but is not essential for other EMT-associated responses including epithelial marker downregulation. TGF-β was previously reported to enhance cell motility by activating Rac1 via phosphoinositide 3-kinase. Intriguingly, TGF-β-dependent signaling mediated by Smad3's β4 region causes the downregulation of multiple mRNAs that encode GTPase activating proteins that target Rac1 (ARHGAPs), thereby attenuating Rac1 inactivation. Therefore, two independent pathways downstream of TGF-β type I receptor contribute cooperatively to sustained Rac1 activation, thereby leading to enhanced cell motility.

Keywords: ARHGAP; Rac1; Smad; cell motility.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

A549 Cells
Cell Movement*
Epithelial-Mesenchymal Transition*
GTPase-Activating Proteins / genetics
GTPase-Activating Proteins / metabolism*
Gene Expression Regulation, Neoplastic / drug effects*
Humans
Phosphatidylinositol 3-Kinases / genetics
Phosphatidylinositol 3-Kinases / metabolism
Phosphorylation
Smad3 Protein / genetics
Smad3 Protein / metabolism*
Transforming Growth Factor beta / pharmacology*
rac1 GTP-Binding Protein / genetics
rac1 GTP-Binding Protein / metabolism*

Substances

ARHGAP1 protein, human
GTPase-Activating Proteins
RAC1 protein, human
SMAD3 protein, human
Smad3 Protein
Transforming Growth Factor beta
rac1 GTP-Binding Protein