title: SUMO regulates the activity of Smoothened and Costal-2 in Drosophila Hedgehog signaling.
abstract: In Hedgehog (Hh) signaling, the GPCR-family protein Smoothened (Smo) acts as a signal transducer that is regulated by phosphorylation and ubiquitination, which ultimately change the cell surface accumulation of Smo. However, it is not clear whether Smo is regulated by other post-translational modifications, such as sumoylation. Here, we demonstrate that knockdown of the small ubiquitin-related modifier (SUMO) pathway components Ubc9 (a SUMO-conjugating enzyme E2), PIAS (a SUMO-protein ligase E3), and Smt3 (the SUMO isoform in Drosophila) by RNAi prevents Smo accumulation and alters Smo activity in the wing. We further show that Hh-induced-sumoylation stabilizes Smo, whereas desumoylation by Ulp1 destabilizes Smo in a phosphorylation independent manner. Mechanistically, we discover that excessive Krz, the Drosophila β-arrestin 2, inhibits Smo sumoylation and prevents Smo accumulation through Krz regulatory domain. Krz likely facilitates the interaction between Smo and Ulp1 because knockdown of Krz by RNAi attenuates Smo-Ulp1 interaction. Finally, we provide evidence that Cos2 is also sumoylated, which counteracts its inhibitory role on Smo accumulation in the wing. Taken together, we have uncovered a novel mechanism for Smo activation by sumoylation that is regulated by Hh and Smo interacting proteins.
authors.affiliation: Markey Cancer Center, Department of Molecular and Cellular Biochemistry, The University of Kentucky College of Medicine, Lexington, KY 40536, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Markey Cancer Center, Department of Molecular and Cellular Biochemistry, The University of Kentucky College of Medicine, Lexington, KY 40536, USA.
authors.forename: Yajuan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Markey Cancer Center, Department of Molecular and Cellular Biochemistry, The University of Kentucky College of Medicine, Lexington, KY 40536, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Jiang
authors.affiliation: Markey Cancer Center, Department of Molecular and Cellular Biochemistry, The University of Kentucky College of Medicine, Lexington, KY 40536, USA.
authors.forename: Jianhang
authors.initials: J
authors.lastname: Jia
mesh_terms: D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics / Q000378:metabolism*; D000072086:Smoothened Receptor / Q000235:genetics / Q000378:metabolism*; D058207:Sumoylation; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism; D014921:Wings, Animal / Q000378:metabolism; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: D019390:Arrestins; D029721:Drosophila Proteins; D053823:Hedgehog Proteins; D012097:Repressor Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D000072086:Smoothened Receptor; C107452:cos protein, Drosophila; C412169:krz protein, Drosophila; C100664:smo protein, Drosophila; C490960:smt3 protein, Drosophila; D044763:Ubiquitin-Conjugating Enzymes; D003546:Cysteine Endopeptidases; C118083:Ulp1 protease; D016547:Kinesins; D000098843:Ubiquitin-Conjugating Enzyme UBC9