Browsing by Subject "Smoothened Receptor"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Identification of select glucocorticoids as Smoothened agonists: potential utility for regenerative medicine.
    (Proc Natl Acad Sci U S A, 2010-05-18) Wang, Jiangbo; Lu, Jiuyi; Bond, Michael C; Chen, Minyong; Ren, Xiu-Rong; Lyerly, H Kim; Barak, Larry S; Chen, Wei
    Regenerative medicine holds the promise of replacing damaged tissues largely by stem cell activation. Hedgehog signaling through the plasma membrane receptor Smoothened (Smo) is an important process for regulating stem cell proliferation. The development of Hedgehog-related therapies has been impeded by a lack of US Food and Drug Administration (FDA)-approved Smo agonists. Using a high-content screen with cells expressing Smo receptors and a beta-arrestin2-GFP reporter, we identified four FDA-approved drugs, halcinonide, fluticasone, clobetasol, and fluocinonide, as Smo agonists that activate Hedgehog signaling. These drugs demonstrated an ability to bind Smo, promote Smo internalization, activate Gli, and stimulate the proliferation of primary neuronal precursor cells alone and synergistically in the presence of Sonic Hedgehog protein. Halcinonide, fluticasone, clobetasol, and fluocinonide provide an unprecedented opportunity to develop unique clinical strategies to treat Hedgehog-dependent illnesses.
  • Thumbnail Image
    ItemRestricted
    Smoothened signal transduction is promoted by G protein-coupled receptor kinase 2.
    (Mol Cell Biol, 2006-10) Meloni, AR; Fralish, GB; Kelly, P; Salahpour, A; Chen, JK; Wechsler Reya, RJ; Lefkowitz, RJ; Caron, MG
    Deregulation of the Sonic hedgehog pathway has been implicated in an increasing number of human cancers. In this pathway, the seven-transmembrane (7TM) signaling protein Smoothened regulates cellular proliferation and differentiation through activation of the transcription factor Gli. The activity of mammalian Smoothened is controlled by three different hedgehog proteins, Indian, Desert, and Sonic hedgehog, through their interaction with the Smoothened inhibitor Patched. However, the mechanisms of signal transduction from Smoothened are poorly understood. We show that a kinase which regulates signaling by many "conventional" 7TM G-protein-coupled receptors, G protein-coupled receptor kinase 2 (GRK2), participates in Smoothened signaling. Expression of GRK2, but not catalytically inactive GRK2, synergizes with active Smoothened to mediate Gli-dependent transcription. Moreover, knockdown of endogenous GRK2 by short hairpin RNA (shRNA) significantly reduces signaling in response to the Smoothened agonist SAG and also inhibits signaling induced by an oncogenic Smoothened mutant, Smo M2. We find that GRK2 promotes the association between active Smoothened and beta-arrestin 2. Indeed, Gli-dependent signaling, mediated by coexpression of Smoothened and GRK2, is diminished by beta-arrestin 2 knockdown with shRNA. Together, these data suggest that GRK2 plays a positive role in Smoothened signaling, at least in part, through the promotion of an association between beta-arrestin 2 and Smoothened.