title: Hey bHLH Proteins Interact with a FBXO45 Containing SCF Ubiquitin Ligase Complex and Induce Its Translocation into the Nucleus.
abstract: The Hey protein family, comprising Hey1, Hey2 and HeyL in mammals, conveys Notch signals in many cell types. The helix-loop-helix (HLH) domain as well as the Orange domain, mediate homo- and heterodimerization of these transcription factors. Although distinct interaction partners have been identified so far, their physiological relevance for Hey functions is still largely unclear. Using a tandem affinity purification approach and mass spectrometry analysis we identified members of an ubiquitin E3-ligase complex consisting of FBXO45, PAM and SKP1 as novel Hey1 associated proteins. There is a direct interaction between Hey1 and FBXO45, whereas FBXO45 is needed to mediate indirect Hey1 binding to SKP1. Expression of Hey1 induces translocation of FBXO45 and PAM into the nucleus. Hey1 is a short-lived protein that is degraded by the proteasome, but there is no evidence for FBXO45-dependent ubiquitination of Hey1. On the contrary, Hey1 mediated nuclear translocation of FBXO45 and its associated ubiquitin ligase complex may extend its spectrum to additional nuclear targets triggering their ubiquitination. This suggests a novel mechanism of action for Hey bHLH factors.
authors.affiliation: Developmental Biochemistry, Theodor-Boveri-Institute, Biocenter, University of Wuerzburg, Wuerzburg, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Salat
authors.affiliation: Developmental Biochemistry, Theodor-Boveri-Institute, Biocenter, University of Wuerzburg, Wuerzburg, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Winkler
authors.affiliation: Bioanalytical Mass Spectrometry, Max-Planck-Institute of Biophysical Chemistry, and Bioanalytics, Institute for Clinical Chemistry, University Medical Center, Goettingen, Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Urlaub
authors.affiliation: Developmental Biochemistry, Theodor-Boveri-Institute, Biocenter, University of Wuerzburg, Wuerzburg, Germany; Comprehensive Cancer Center Mainfranken, Wuerzburg University, Wuerzburg, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Gessler
mesh_terms: D021581:Active Transport, Cell Nucleus; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D044783:F-Box Proteins / Q000378:metabolism*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D011485:Protein Binding; D043743:Ubiquitin-Protein Ligase Complexes / Q000378:metabolism*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D018797:Cell Cycle Proteins; D044783:F-Box Proteins; D043743:Ubiquitin-Protein Ligase Complexes; C503710:FBXO45 protein, human; C485631:HEY1 protein, human