title: Unfolded protein response transcription factor XBP-1 does not influence prion replication or pathogenesis.
abstract: The unfolded protein response (UPR) is a conserved adaptive reaction that increases cell survival under endoplasmic reticulum (ER) stress conditions. X-box-binding protein-1 (XBP-1) is a key transcriptional regulator of the UPR that activates genes involved in protein folding, secretion, and degradation to restore ER function. The occurrence of chronic ER stress has been extensively described in neurodegenerative conditions linked to protein misfolding and aggregation. However, the role of the UPR in the CNS has not been addressed directly. Here we describe the generation of a brain-specific XBP-1 conditional KO strain (XBP-1(Nes-/-)). XBP-1(Nes-/-) mice are viable and do not develop any spontaneous neurological dysfunction, although ER stress signaling in XBP-1(Nes-/-) primary neuronal cell cultures was impaired. To assess the function of XBP-1 in pathological conditions involving protein misfolding and ER stress, we infected XBP-1(Nes-/-) mice with murine prions. To our surprise, the activation of stress responses triggered by prion replication was not influenced by XBP-1 deficiency. Neither prion aggregation, neuronal loss, nor animal survival was affected. Hence, this most highly conserved arm of the UPR may not contribute to the occurrence or pathology of neurodegenerative conditions associated with prion protein misfolding despite predictions that such diseases are related to ER stress and irreversible neuronal damage.
authors.affiliation: Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA. chetz@med.uchile.cl
authors.forename: Claudio
authors.initials: C
authors.lastname: Hetz
authors.forename: Ann-Hwee
authors.initials: AH
authors.lastname: Lee
authors.forename: Dennisse
authors.initials: D
authors.lastname: Gonzalez-Romero
authors.forename: Peter
authors.initials: P
authors.lastname: Thielen
authors.forename: Joaquín
authors.initials: J
authors.lastname: Castilla
authors.forename: Claudio
authors.initials: C
authors.lastname: Soto
authors.forename: Laurie H
authors.initials: LH
authors.lastname: Glimcher
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation; D006624:Hippocampus / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D019636:Neurodegenerative Diseases / Q000235:genetics; D009474:Neurons / Q000378:metabolism; D011328:Prions / Q000378:metabolism*; D011489:Protein Denaturation; D017510:Protein Folding; D000071701:Regulatory Factor X Transcription Factors; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology*; D000071717:X-Box Binding Protein 1
chemical_list: D004268:DNA-Binding Proteins; D011328:Prions; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605544:Xbp1 protein, mouse