Activation of rac and cdc42 video imaged by fluorescent resonance energy transfer-based single-molecule probes in the membrane of living cells.
Rho family G proteins, including Rac and Cdc42, regulate a variety of cellular functions such as morphology, motility, and gene expression. We developed fluorescent resonance energy transfer-based probes which monitored the local balance between the activities of guanine nucleotide exchange factors and GTPase-activating proteins for Rac1 and Cdc42 at the membrane. These probes, named Raichu-Rac and Raichu-Cdc42, consisted of a Cdc42- and Rac-binding domain of Pak, Rac1 or Cdc42, a pair of green fluorescent protein mutants, and a CAAX box of Ki-Ras. With these probes, we video imaged the Rac and Cdc42 activities. In motile HT1080 cells, activities of both Rac and Cdc42 gradually increased toward the leading edge and decreased rapidly when cells changed direction. Under a higher magnification, we observed that Rac activity was highest immediately behind the leading edge, whereas Cdc42 activity was most prominent at the tip of the leading edge. Raichu-Rac and Raichu-Cdc42 were also applied to a rapid and simple assay for the analysis of putative guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) in living cells. Among six putative GEFs and GAPs, we identified KIAA0362/DBS as a GEF for Rac and Cdc42, KIAA1256 as a GEF for Cdc42, KIAA0053 as a GAP for Rac and Cdc42, and KIAA1204 as a GAP for Cdc42. In conclusion, use of these single-molecule probes to determine Rac and Cdc42 activity will accelerate the analysis of the spatiotemporal regulation of Rac and Cdc42 in a living cell.
Department of Tumor Virology, Research Institute for Microbial Diseases, Osaka University, CREST, Japan.
Reina E
RE
Itoh
Kazuo
K
Kurokawa
Yusuke
Y
Ohba
Hisayoshi
H
Yoshizaki
Naoki
N
Mochizuki
Michiyuki
M
Matsuda
D000256:Adenoviridae / Q000378:metabolism; D000818:Animals; D019556:COS Cells; D002460:Cell Line; D018076:DNA, Complementary / Q000378:metabolism; D004735:Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry*; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006147:Guanine / Q000737:chemistry; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008164:Luminescent Proteins / Q000737:chemistry* / Q000235:genetics; D008566:Membranes / Q000378:metabolism; D018715:Microscopy, Video / Q000379:methods*; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013997:Time Factors; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D018631:ras Proteins / Q000378:metabolism
D018076:DNA, Complementary; D005456:Fluorescent Dyes; D008164:Luminescent Proteins; D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D006147:Guanine; D006160:Guanosine Triphosphate; C430804:Raichu-Ras protein; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D018631:ras Proteins