Chemotaxis in a lymphocyte cell line transfected with C-C chemokine receptor 2B: Evidence that directed migration is mediated by βγ dimers released by activation of Gαi-coupled receptors

Chemotaxis in a lymphocyte cell line transfected with C-C chemokine receptor 2B: Evidence that directed migration is mediated by βγ dimers released by activation of G_αi-coupled receptors

^*Gladstone Institute of Cardiovascular Disease, ^†Cardiovascular Research Institute, ^¶Department of Medicine, and ^§Daiichi Research Center, University of California, San Francisco, CA 94141-9100

Edited by Melvin I. Simon, California Institute of Technology, Pasadena, CA, and approved November 7, 1997 (received for review July 18, 1997)

Abstract

Chemotaxis is mediated by activation of seven-transmembrane domain, G protein-coupled receptors, but the signal transduction pathways leading to chemotaxis are poorly understood. To identify G proteins that signal the directed migration of cells, we stably transfected a lymphocyte cell line (300-19) with G protein-coupled receptors that couple exclusively to G_αq (the m3 muscarinic receptor), G_αi (the κ-opioid receptor), and G_αs (the β-adrenergic receptor), as well as the human thrombin receptor (PAR-1) and the C-C chemokine receptor 2B. Cells expressing receptors that coupled to G_αi, but not to G_αq or G_αs, migrated in response to a concentration gradient of the appropriate agonist. Overexpression of G_α transducin, which binds to and inactivates free G_βγ dimers, completely blocked chemotaxis although having little or no effect on intracellular calcium mobilization or other measures of cell signaling. The identification of G_βγ dimers as a crucial intermediate in the chemotaxis signaling pathway provides further evidence that chemotaxis of mammalian cells has important similarities to polarized responses in yeast. We conclude that chemotaxis is dependent on activation of G_αi and the release of G_βγ dimers, and that G_αi-coupled receptors not traditionally associated with chemotaxis can mediate directed migration when they are expressed in hematopoietic cells.

Footnotes

↵ ‡ Present address: Department of Geriatric Medicine, Kyoto University Hospital, 54 Kawahara-Cho, Shogoin, Sakyo-Ku, Kyoto 606-01, Japan.
↵ ‖ To whom reprint requests should be addressed at: Gladstone Institute of Cardiovascular Disease, P.O. Box 419100, San Francisco, CA 94141-9100. e-mail: izzy_charo.gicd{at}quickmail.ucsf.edu.
This paper was submitted directly (Track II) to the Proceedings Office.
Abbreviations: CCR, C-C chemokine receptor; ERK, extracellular signal-regulated kinase; FACS, fluorescence-activated cell sorter; G_αt, G_α transducin; MCP-1, monocyte chemoattractant protein 1; PAR-1, protease-activated receptor 1; PTX, pertussis toxin.