title: Dual Phosphorylation of suppressor of fused (Sufu) by PKA and GSK3beta regulates its stability and localization in the primary cilium.
abstract: Suppressor of fused (Sufu) is an essential negative regulator of the sonic hedgehog (Shh) pathway, but little is known about how Sufu itself is normally regulated. Here, we report that Sufu is phosphorylated at Ser-342 and Ser-346 by GSK3β and cAMP-dependent protein kinase A (PKA), respectively, and phosphorylation at this dual site stabilizes Sufu against Shh signaling-induced degradation. We further show that localization of Sufu in the primary cilium is induced by Shh signaling and is required for the turnover of both phosphorylated and total Sufu. Perturbing Sufu phosphorylation with PKA inhibitors or replacing Ser-346 with alanine reduced the stay and replacing Ser-342 and Ser-346 with aspartic acid prolonged the stay of Sufu in the cilia. Finally, ciliary localization of Gli2/3 also required Smo and was similarly influenced by perturbations of PKA activity or mutations at the dual Sufu phosphorylation site. Thus, Shh likely induced trafficking of phospho-Sufu into the primary cilium in a complex with Gli2/3, and dephosphorylation triggered a retrograde export, allowing Sufu to be degraded by the ubiquitin-proteasome system.
authors.affiliation: Department of Developmental Genetics, Center for Cancer Research, Nanjing Medical University, Nanjing, Jiansu 210029, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.forename: Shen
authors.initials: S
authors.lastname: Yue
authors.forename: Lu
authors.initials: L
authors.lastname: Xie
authors.forename: Xiao-hong
authors.initials: XH
authors.lastname: Pu
authors.forename: Tian
authors.initials: T
authors.lastname: Jin
authors.forename: Steven Y
authors.initials: SY
authors.lastname: Cheng
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D002923:Cilia / Q000235:genetics / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D057809:HEK293 Cells; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism; D051379:Mice; D020125:Mutation, Missense; D041681:NIH 3T3 Cells; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000502:physiology; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism; D055550:Protein Stability; D021381:Protein Transport / Q000502:physiology; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism; D000075746:Zinc Finger Protein Gli2; D000074290:Zinc Finger Protein Gli3
chemical_list: C082593:GLI2 protein, human; C065683:GLI3 protein, human; C000618551:Gli2 protein, mouse; C465571:Gli3 protein, mouse; D053823:Hedgehog Proteins; D051741:Kruppel-Like Transcription Factors; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; C509239:SHH protein, human; C490764:SUFU protein, human; C465570:Shh protein, mouse; C490763:Sufu protein, mouse; D025801:Ubiquitin; D000075746:Zinc Finger Protein Gli2; D000074290:Zinc Finger Protein Gli3; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D017868:Cyclic AMP-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3; D046988:Proteasome Endopeptidase Complex