title: Different mechanisms of recognition and ER retention by transmembrane transcription factors CREB-H and ATF6.
abstract: CREB-H and activating transcription factor 6 (ATF6) are transmembrane transcription factors that, in response to endoplasmic reticulum (ER) stress, traffic to the Golgi where they are cleaved by specific proteases, producing the N-terminal domains that effect appropriate transcriptional responses. We show that unlike in ATF6 whose lumenal tail binds BiP and contains determinants for stress sensing and Golgi transport, in CREB-H the lumenal tail is not involved in ER retention, not required for Golgi transport and does not bind BiP. The main determinant for CREB-H ER retention resides in a membrane-proximal cytoplasmic determinant that is conserved in related members of the CREB-H family, but lacking in ATF6. We refine requirements within the ER-retention motif (ERM) and show that ERM-ve variants exhibited constitutive Golgi localization and constitutive cleavage by the Golgi protease, S1P. The ERM also conferred ER retention on a heterologous protein. Furthermore, deletion of the lumenal tail of CREB-H had no effect on ER retention of parental CREB-H or Golgi localization of ERM-ve variants. Importantly, when the lumenal tail of ATF6 was transferred into an ERM-ve variant, the chimera was now retained in the ER. Together, these data demonstrate novel and qualitatively distinct mechanisms of trafficking and stress signalling in CREB-H compared to ATF6.
authors.affiliation: Marie Curie Research Institute, The Chart, Oxted, Surrey RH8 0TL, UK.
authors.forename: Marta
authors.initials: M
authors.lastname: Llarena
authors.forename: Daniel
authors.initials: D
authors.lastname: Bailey
authors.forename: Helen
authors.initials: H
authors.lastname: Curtis
authors.forename: Peter
authors.initials: P
authors.lastname: O'Hare
mesh_terms: D051702:Activating Transcription Factor 6 / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D018929:Cell Culture Techniques; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000235:genetics / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D047468:Immunoprecipitation; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids; D043484:Proprotein Convertases / Q000037:antagonists & inhibitors / Q000378:metabolism; D017510:Protein Folding; D021381:Protein Transport; D012697:Serine Endopeptidases / Q000378:metabolism; D013312:Stress, Physiological; D014162:Transfection
chemical_list: C497111:ATF6 protein, human; D051702:Activating Transcription Factor 6; C533813:CREB3L3 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D043484:Proprotein Convertases; D012697:Serine Endopeptidases; C115575:membrane-bound transcription factor peptidase, site 1