title: UV-induced degradation of securin is mediated by SKP1-CUL1-beta TrCP E3 ubiquitin ligase.
abstract: Securin is a chaperone protein with bifunctional properties. It binds to separase to inhibit premature sister chromatid separation until the onset of anaphase, and it also takes part in cell-cycle arrest after UV irradiation. At metaphase-to-anaphase transition, securin is targeted for proteasomal destruction by the anaphase-promoting complex or cyclosome (APC/C), allowing activation of separase. However, although securin is reported to undergo proteasome-dependent degradation after UV irradiation, the ubiquitin ligase responsible for securin ubiquitylation has not been well characterized. In this study, we show that UV radiation induced a marked reduction of securin in both the nucleus and cytoplasm. Moreover, we show that GSK-3beta inhibitors prevent securin degradation, and that CUL1 and betaTrCP are involved in this depletion. We also confirmed that SKP1-CUL1-betaTrCP (SCF(betaTrCP)) ubiquitylates securin in vivo, and identified a conserved and unconventional betaTrCP recognition motif (DDAYPE) in the securin primary amino acid sequence of humans, nonhuman primates and rodents. Furthermore, downregulation of betaTrCP caused an accumulation of securin in non-irradiated cells. We conclude that SCF(betaTrCP) is the E3 ubiquitin ligase responsible for securin degradation after UV irradiation, and that it is involved in securin turnover in nonstressed cells.
authors.affiliation: Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain.
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Limón-Mortés
authors.forename: Mar
authors.initials: M
authors.lastname: Mora-Santos
authors.forename: Agueda
authors.initials: A
authors.lastname: Espina
authors.forename: José A
authors.initials: JA
authors.lastname: Pintor-Toro
authors.forename: Antonio
authors.initials: A
authors.lastname: López-Román
authors.forename: María
authors.initials: M
authors.lastname: Tortolero
authors.forename: Francisco
authors.initials: F
authors.lastname: Romero
mesh_terms: D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D019556:COS Cells; D002453:Cell Cycle / Q000502:physiology / Q000528:radiation effects; D018797:Cell Cycle Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism / Q000528:radiation effects; D002522:Chlorocebus aethiops; D044842:Cullin Proteins / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism / Q000528:radiation effects; D015536:Down-Regulation / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006367:HeLa Cells; D006801:Humans; D009363:Neoplasm Proteins / Q000378:metabolism* / Q000528:radiation effects; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism; D064249:Securin; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D054875:Ubiquitination / Q000502:physiology / Q000528:radiation effects*; D014466:Ultraviolet Rays; D044844:beta-Transducin Repeat-Containing Proteins / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; C100318:Cullin 1; D044842:Cullin Proteins; D004791:Enzyme Inhibitors; D009363:Neoplasm Proteins; D064249:Securin; D044844:beta-Transducin Repeat-Containing Proteins; C578002:pituitary tumor-transforming protein 1, human; D044843:SKP Cullin F-Box Protein Ligases; D044767:Ubiquitin-Protein Ligases; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; D046988:Proteasome Endopeptidase Complex