Smoothened Activates Gαi-mediated Signaling in Frog Melanophores*

By D. Decamp, T. Thompson, F. D. de Sauvage, M. Lerner. Journal of Biological Chemistry, 2000

98 citations recorded by the source corpus.

The 7-pass transmembrane protein Smoothened was investigated for its ability to act as a G-protein-coupled receptor inXenopus laevis melanophores. A plasmid containing the human Smoothened cDNA insert was transfected into immortalized frog pigment cells. Cells expressing the protein showed a phenotype of persistent pigment aggregation, a hallmark of constitutive Gαi activation. Smoothened-mediated pigment aggregation was reversed by treatment with pertussis toxin or by co-expression with dominant negative Gαi. The ability of melanophores to express functional Smoothened was also determined by its co-expression with the twelve-pass transmembrane protein, Patched. Patched blocked Smoothened-mediated melanosome aggregation in a dose-dependent manner, consistent with its physiological role as an inhibitor of Smoothened. That the reconstituted Patched-Smoothened receptor complex functions normally in pigment cells was demonstrated by co-transfection with the activating ligand, Sonic hedgehog, as well as by direct application of the recombinant Sonic hedgehog protein. Sonic hedgehog reversed Patched-mediated inhibition of Smoothened and induced pigment aggregation. The findings demonstrate that the human Sonic hedgehog receptor complex can be functionally reconstituted in melanophores and that it is capable of transmembrane signaling by utilizing endogenous Gαi.

Subfields: Genetics, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/eaf3cde9116cfe68118dfd9abf4d85414e4e2858

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Citations in the corpus

Proximal events in Wnt signal transduction (2009, background): “Interestingly, whether signalling by the Smoothened ( Smo ) family of receptors (which are homologous to the Frizzled receptors) in the Hedgehog pathway also involves heterotrimeric G proteins has also been debate”
Hedgehog signaling in animal development: paradigms and principles. (2001, background): “In a classic assay for G i activation, expression of human Smo in Xenopusmelanophores appears sufficient to stimulate persistent pigment aggregation in these cells, an effect that can be blocked by pertussis toxin (DeCamp et al. 2000).”
Hedgehog Signaling in Development and Cancer (2008, unknown): “While several studies using pharmacological inhibitors and overexpression implied that Smo might couple to several G proteins (DeCamp et al., 2000; Kasai et al., 2004; Riobo et al., 2006b), others disputed such coupling or its biological signiﬁcance (Murone et al., 1999; Low et al., 2008).”