WNT-5A stimulates the GDP/GTP exchange at pertussis toxin-sensitive heterotrimeric G proteins.
The lipoglycoproteins of the WNT family act on seven transmembrane-spanning Class Frizzled receptors. Here, we show that WNT-5A evokes a proliferative response in a mouse microglia-like cell line (N13), which is sensitive to pertussis toxin, thus implicating the involvement of heterotrimeric G proteins of the G(i/o) family. We continue to show that WNT-5A stimulation of N13 membranes and permeabilized cells evokes the exchange of GDP for GTP of pertussis toxin-sensitive G proteins employing [γ-(35)S]GTP assay and activity state-specific antibodies to GTP-bound G(i) proteins. Our functional analysis of the PTX-sensitivity of WNT-induced G protein activation and PCR analysis of G protein and FZD expression patterns suggest that WNT-5A stimulation leads to the activation of G(i2/3) proteins in N13 cells possibly mediated by FZD(5), the predominant FZD expressed. In summary, we provide for the first time molecular proof that WNT-5A stimulation results in the activation of heterotrimeric G(i2/3) proteins in mammalian cells with physiological protein stochiometry.
Section of Receptor Biology and Signaling, Dept. of Physiology and Pharmacology, Karolinska Institutet, S-171 77 Stockholm, Sweden.
Michaela Bc
MB
Kilander
Jacomijn P
JP
Dijksterhuis
Ranjani Sri
RS
Ganji
Vitezslav
V
Bryja
Gunnar
G
Schulte
D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation; D006153:Guanosine Diphosphate / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D051379:Mice; D037342:Pertussis Toxin / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D015398:Signal Transduction; D051153:Wnt Proteins / Q000502:physiology*; D000071818:Wnt-5a Protein
D011956:Receptors, Cell Surface; D051153:Wnt Proteins; D000071818:Wnt-5a Protein; C438615:Wnt5a protein, mouse; C093426:pertussis toxin receptor; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D037342:Pertussis Toxin; D020962:Heterotrimeric GTP-Binding Proteins