Activation of rat frizzled-1 promotes Wnt signaling and differentiation of mouse F9 teratocarcinoma cells via pathways that require Galpha(q) and Galpha(o) function.
The frizzled gene family of putative Wnt receptors encodes proteins that have a seven transmembrane-spanning motif characteristic of G-protein-linked receptors, although no loss-of-function studies have demonstrated a requirement for G-proteins for Wnt signaling by the gene product of frizzled-1. Medium conditioned by mouse F9 teratocarcinoma stem cells stably transfected to express either Xenopus Wnt-5a or Wnt-8 was used to test primitive endoderm formation of F9 stem cells. F9 stem cells expressing the rat Frizzled-1 receptors demonstrated endoderm formation in response to conditioned medium containing Wnt-8 but not to medium containing Wnt-5a. Primitive endoderm formation stimulated by Wnt-8 acting on the rat Frizzled-1 receptor was blocked by treatment with pertussis toxin by depletion of either Galpha(o) or Galpha(q) via antisense oligodeoxynucleotides, as well as by inhibitors of protein kinase C (bisindoylmaleimide) and of mitogen-activated protein kinase kinase (PD98059). Our results demonstrate the requirement for G-protein subunits Galpha(o) (a pertussis toxin substrate) and Galpha(q) for signaling by Frizzled-1, and an obligate role for the protein kinase C (likely mediated through stimulation of Galpha(q)) and mitogen-activated protein kinase network at the level of mitogen-activated protein kinase kinase.
Liu
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Department of Pharmacology, State University of New York, Stony Brook, New York 11794-8651, USA.
Liu
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Wang
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Moon
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Malbon
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D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors; D000818:Animals; D002999:Clone Cells; D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019084:Fluorescent Antibody Technique, Indirect; D051157:Frizzled Receptors; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048728:MAP Kinase Kinase Kinase 1; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors; D051379:Mice; D037342:Pertussis Toxin; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051381:Rats; D043562:Receptors, G-Protein-Coupled; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D015398:Signal Transduction; D018243:Teratocarcinoma / Q000378:metabolism* / Q000473:pathology; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D051153:Wnt Proteins; D029867:Xenopus Proteins; D029961:Zebrafish Proteins
D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors; C489741:FZD1 protein, Xenopus; D051157:Frizzled Receptors; C489739:Fzd1 protein, mouse; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D043562:Receptors, G-Protein-Coupled; D017981:Receptors, Neurotransmitter; D010566:Virulence Factors, Bordetella; D051153:Wnt Proteins; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; C078603:Fzd1 protein, rat; D037342:Pertussis Toxin; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D048728:MAP Kinase Kinase Kinase 1; D020930:MAP Kinase Kinase Kinases; C482578:Map3k1 protein, mouse; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D019204:GTP-Binding Proteins