Published online 3 June 2002. doi:10.1083/jcb.200112070
© The Rockefeller University Press,
0021-9525/2002/6/921 $5.00
The Journal of Cell Biology, Volume 157, Number 6, June 10, 2002 921-928
Genetic analysis of the role of G proteincoupled receptor signaling in electrotaxis
Min Zhao1,
Tian Jin2,
Colin D. McCaig1,
John V. Forrester3 and
Peter N. Devreotes2
1 Department of Biomedical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom
2 Department of Cell Biology and Anatomy, Johns Hopkins University School of Medicine, Baltimore, MD 21205
3 Department of Ophthalmology, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom
Address correspondence to Min Zhao, Dept. of Biomedical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK. Tel.: 44-1224-273001. Fax: 44-1224-273019. E-mail: m.zhao{at}abdn.ac.uk
Cells display chemotaxis and electrotaxis by migrating directionally in gradients of specific chemicals or electrical potential. Chemotaxis in Dictyostelium discoideum is mediated by G proteincoupled receptors. The unique Gß is essential for all chemotactic responses, although different chemoattractants use different receptors and G
subunits. Dictyostelium amoebae show striking electrotaxis in an applied direct current electric field. Perhaps electrotaxis and chemotaxis share similar signaling mechanisms? Null mutation of Gß and cAMP receptor 1 and G
2 did not abolish electrotaxis, although Gß-null mutations showed suppressed electrotaxis. By contrast, G protein signaling plays an essential role in chemotaxis. G proteincoupled receptor signaling was monitored with PHcracgreen fluorescent protein, which translocates to inositol phospholipids at the leading edge of cells during chemotaxis. There was no intracellular gradient of this protein during electrotaxis. However, F-actin was polymerized at the leading edge of cells during electrotaxis. We conclude that reception and transduction of the electrotaxis signal are largely independent of G proteincoupled receptor signaling and that the pathways driving chemotaxis and electrotaxis intersect downstream of heterotrimeric G proteins to invoke cytoskeletal elements.
Key Words: Dictyostelium; cell migration; electrotaxis; electric fields; G proteincoupled receptor signaling

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