title: Phosphorylation and SCF-mediated degradation regulate CREB-H transcription of metabolic targets.
abstract: CREB‑H, an endoplasmic reticulum-anchored transcription factor, plays a key role in regulating secretion and in metabolic and inflammatory pathways, but how its activity is modulated remains unclear. We examined processing of the nuclear active form and identified a motif around S87-S90 with homology to DSG-type phosphodegrons. We show that this region is subject to multiple phosphorylations, which regulate CREB-H stability by targeting it to the SCF(Fbw1a) E3 ubiquitin ligase. Data from phosphatase treatment, use of phosophospecific antibody, and substitution of serine residues demonstrate phosphorylation of candidate serines in the region, with the core S87/S90 motif representing a critical determinant promoting proteasome-mediated degradation. Candidate kinases CKII and GSK-3b phosphorylate CREB-H in vitro with specificities for different serines. Prior phosphorylation with GSK-3 at one or more of the adjacent serines substantially increases S87/S90-dependent phosphorylation by CKII. In vivo expression of a dominant-negative Cul1 enhances steady-state levels of CREB‑H, an effect augmented by Fbw1a. CREB-H directly interacts with Fbw1a in a phosphorylation-dependent manner. Finally, mutations within the phosphodegron, when incorporated into the full-length protein, result in increased levels of constitutively cleaved nuclear protein and increased transcription and secretion of a key endogenous target gene, apolipoprotein A IV.
authors.affiliation: Department of Medicine, Imperial College, London W2 1PG, United Kingdom.
authors.forename: Sónia
authors.initials: S
authors.lastname: Barbosa
authors.affiliation: Department of Medicine, Imperial College, London W2 1PG, United Kingdom.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Carreira
authors.affiliation: Health Protection Agency, Porton Down, Salisbury SP4 0JG, United Kingdom.
authors.forename: Daniel
authors.initials: D
authors.lastname: Bailey
authors.affiliation: Department of Medicine, Imperial College, London W2 1PG, United Kingdom.
authors.forename: Fernando
authors.initials: F
authors.lastname: Abaitua
authors.affiliation: Department of Medicine, Imperial College, London W2 1PG, United Kingdom pohare@imperial.ac.uk.
authors.forename: Peter
authors.initials: P
authors.lastname: O'Hare
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D051379:Mice; D010766:Phosphorylation; D050436:Regulatory Elements, Transcriptional; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D025801:Ubiquitin / Q000378:metabolism
chemical_list: C500051:Creb3l3 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D025801:Ubiquitin; D044843:SKP Cullin F-Box Protein Ligases