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Greenwood M, Gillard BT, Murphy D, Greenwood MP. Dimerization of hub protein DYNLL1 and bZIP transcription factor CREB3L1 enhances transcriptional activation of CREB3L1 target genes like arginine vasopressin. Peptides 2024:171269. [PMID: 38960286 DOI: 10.1016/j.peptides.2024.171269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 06/29/2024] [Accepted: 07/01/2024] [Indexed: 07/05/2024]
Abstract
bZIP transcription factors can function as homodimers or heterodimers through interactions with their disordered coiled-coil domain. Such dimer assemblies are known to influence DNA-binding specificity and/or the recruitment of binding partners, which can cause a functional switch of a transcription factor from being an activator to a repressor. We recently identified the genomic targets of a bZIP transcription factor called CREB3L1 in rat hypothalamic supraoptic nucleus by ChIP-seq. The objective of this study was to investigate the CREB3L1 protein-to-protein interactome of which little is known. For this approach, we created and screened a rat supraoptic nucleus yeast two-hybrid prey library with the bZIP region of rat CREB3L1 as the bait. Our yeast two-hybrid approach captured five putative CREB3L1 interacting prey proteins in the supraoptic nucleus. One interactor was selected by bioinformatic analyses for more detailed investigation by co-immunoprecipitation, immunofluorescent cellular localisation, and reporter assays in vitro. Here we identify dimerisation hub protein Dynein Light Chain LC8-Type 1 as a CREB3L1 interacting protein that in vitro enhances CREB3L1 activation of target genes.
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Affiliation(s)
- Mingkwan Greenwood
- Molecular Neuroendocrinology Research Group, Bristol Medical School: Translational Health Sciences, University of Bristol, Dorothy Hodgkin Building, Bristol, United Kingdom
| | - Benjamin T Gillard
- Molecular Neuroendocrinology Research Group, Bristol Medical School: Translational Health Sciences, University of Bristol, Dorothy Hodgkin Building, Bristol, United Kingdom
| | - David Murphy
- Molecular Neuroendocrinology Research Group, Bristol Medical School: Translational Health Sciences, University of Bristol, Dorothy Hodgkin Building, Bristol, United Kingdom
| | - Michael P Greenwood
- Molecular Neuroendocrinology Research Group, Bristol Medical School: Translational Health Sciences, University of Bristol, Dorothy Hodgkin Building, Bristol, United Kingdom.
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Le Goupil S, Laprade H, Aubry M, Chevet E. Exploring the IRE1 interactome: From canonical signaling functions to unexpected roles. J Biol Chem 2024; 300:107169. [PMID: 38494075 PMCID: PMC11007444 DOI: 10.1016/j.jbc.2024.107169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 03/04/2024] [Accepted: 03/08/2024] [Indexed: 03/19/2024] Open
Abstract
The unfolded protein response is a mechanism aiming at restoring endoplasmic reticulum (ER) homeostasis and is likely involved in other adaptive pathways. The unfolded protein response is transduced by three proteins acting as sensors and triggering downstream signaling pathways. Among them, inositol-requiring enzyme 1 alpha (IRE1α) (referred to as IRE1 hereafter), an endoplasmic reticulum-resident type I transmembrane protein, exerts its function through both kinase and endoribonuclease activities, resulting in both X-box binding protein 1 mRNA splicing and RNA degradation (regulated ire1 dependent decay). An increasing number of studies have reported protein-protein interactions as regulators of these signaling mechanisms, and additionally, driving other noncanonical functions. In this review, we deliver evolutive and structural insights on IRE1 and further describe how this protein interaction network (interactome) regulates IRE1 signaling abilities or mediates other cellular processes through catalytic-independent mechanisms. Moreover, we focus on newly discovered targets of IRE1 kinase activity and discuss potentially novel IRE1 functions based on the nature of the interactome, thereby identifying new fields to explore regarding this protein's biological roles.
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Affiliation(s)
- Simon Le Goupil
- INSERM U1242, University of Rennes, Rennes, France; Centre de Lutte contre le cancer Eugène Marquis, Rennes, France.
| | - Hadrien Laprade
- INSERM U1242, University of Rennes, Rennes, France; Centre de Lutte contre le cancer Eugène Marquis, Rennes, France
| | - Marc Aubry
- INSERM U1242, University of Rennes, Rennes, France; Centre de Lutte contre le cancer Eugène Marquis, Rennes, France
| | - Eric Chevet
- INSERM U1242, University of Rennes, Rennes, France; Centre de Lutte contre le cancer Eugène Marquis, Rennes, France
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Kelly C, Ahmed Y, Elghawy O, Pachon NF, Fontanese MS, Kim S, Kitterman E, Marley A, Terrenzio D, Wike R, Zeibekis T, Cameron DM. The human ribosome-associated complex suppresses prion formation in yeast. Proteins 2023; 91:715-723. [PMID: 36604744 PMCID: PMC10159891 DOI: 10.1002/prot.26461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 12/21/2022] [Accepted: 12/27/2022] [Indexed: 01/07/2023]
Abstract
Many human diseases are associated with the misfolding of amyloidogenic proteins. Understanding the mechanisms cells employ to ensure the integrity of the proteome is therefore a crucial step in the development of potential therapeutic interventions. Yeast cells possess numerous prion-forming proteins capable of adopting amyloid conformations, possibly as an epigenetic mechanism to cope with changing environmental conditions. The ribosome-associated complex (RAC), which docks near the ribosomal polypeptide exit tunnel and recruits the Hsp70 Ssb to chaperone nascent chains, can moderate the acquisition of these amyloid conformations in yeast. Here we examine the ability of the human RAC chaperone proteins Mpp11 and Hsp70L1 to function in place of their yeast RAC orthologues Zuo1 and Ssz1 in yeast lacking endogenous RAC and investigate the extent to which the human orthologues can perform RAC chaperone activities in yeast. We found that the Mpp11/Hsp70L1 complex can partially correct the growth defect seen in RAC-deficient yeast cells, although yeast/human hetero species complexes were variable in this ability. The proportion of cells in which the Sup35 protein undergoes spontaneous conversion to a [PSI+ ] prion conformation, which is increased in the absence of RAC, was reduced by the presence of the human RAC complex. However, the toxicity in yeast from expression of a pathogenically expanded polyQ protein was unable to be countered by the human RAC chaperones. This yeast system can serve as a facile model for studying the extent to which the human RAC chaperones contribute to combating cotranslational misfolding of other mammalian disease-associated proteins.
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Affiliation(s)
- Christina Kelly
- Biology Department, Ursinus College, Collegeville, PA, 19426, USA
| | - Yusef Ahmed
- Biology Department, Ursinus College, Collegeville, PA, 19426, USA
- Present address: Department of Chemistry, University of California – Davis, Davis, California 95616, USA
| | - Omar Elghawy
- Biology Department, Ursinus College, Collegeville, PA, 19426, USA
- Present address: University of Virginia School of Medicine, Charlottesville, VA, 22903, USA
| | | | - Matthew S. Fontanese
- Biology Department, Ursinus College, Collegeville, PA, 19426, USA
- Present address: Department of clinical psychology; University of Texas at Tyler, Tyler, TX, 75799, USA
| | - Seongchan Kim
- Biology Department, Ursinus College, Collegeville, PA, 19426, USA
| | - Erica Kitterman
- Biology Department, Ursinus College, Collegeville, PA, 19426, USA
- Present address: Department of Cancer Biology, Thomas Jefferson University, Philadelphia, PA, 19107, USA
| | - Amanda Marley
- Biology Department, Ursinus College, Collegeville, PA, 19426, USA
| | - Danielle Terrenzio
- Biology Department, Ursinus College, Collegeville, PA, 19426, USA
- Present address: Doctor of Osteopathic Medicine Program, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, 19131, USA
| | - Richard Wike
- Biology Department, Ursinus College, Collegeville, PA, 19426, USA
- Present address: Physiology Department, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | | | - Dale M. Cameron
- Biology Department, Ursinus College, Collegeville, PA, 19426, USA
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Belyy V, Zuazo-Gaztelu I, Alamban A, Ashkenazi A, Walter P. Endoplasmic reticulum stress activates human IRE1α through reversible assembly of inactive dimers into small oligomers. eLife 2022; 11:e74342. [PMID: 35730415 PMCID: PMC9217129 DOI: 10.7554/elife.74342] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 04/19/2022] [Indexed: 01/24/2023] Open
Abstract
Protein folding homeostasis in the endoplasmic reticulum (ER) is regulated by a signaling network, termed the unfolded protein response (UPR). Inositol-requiring enzyme 1 (IRE1) is an ER membrane-resident kinase/RNase that mediates signal transmission in the most evolutionarily conserved branch of the UPR. Dimerization and/or higher-order oligomerization of IRE1 are thought to be important for its activation mechanism, yet the actual oligomeric states of inactive, active, and attenuated mammalian IRE1 complexes remain unknown. We developed an automated two-color single-molecule tracking approach to dissect the oligomerization of tagged endogenous human IRE1 in live cells. In contrast to previous models, our data indicate that IRE1 exists as a constitutive homodimer at baseline and assembles into small oligomers upon ER stress. We demonstrate that the formation of inactive dimers and stress-dependent oligomers is fully governed by IRE1's lumenal domain. Phosphorylation of IRE1's kinase domain occurs more slowly than oligomerization and is retained after oligomers disassemble back into dimers. Our findings suggest that assembly of IRE1 dimers into larger oligomers specifically enables trans-autophosphorylation, which in turn drives IRE1's RNase activity.
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Affiliation(s)
- Vladislav Belyy
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | | | - Andrew Alamban
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
| | - Avi Ashkenazi
- Cancer Immunology, Genentech, IncSouth San FranciscoUnited States
| | - Peter Walter
- Department of Biochemistry and Biophysics, University of California, San FranciscoSan FranciscoUnited States
- Howard Hughes Medical Institute, University of California, San FranciscoSan FranciscoUnited States
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The Unfolded Protein Response as a Guardian of the Secretory Pathway. Cells 2021; 10:cells10112965. [PMID: 34831188 PMCID: PMC8616143 DOI: 10.3390/cells10112965] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 10/27/2021] [Accepted: 10/29/2021] [Indexed: 02/07/2023] Open
Abstract
The endoplasmic reticulum (ER) is the major site of membrane biogenesis in most eukaryotic cells. As the entry point to the secretory pathway, it handles more than 10,000 different secretory and membrane proteins. The insertion of proteins into the membrane, their folding, and ER exit are affected by the lipid composition of the ER membrane and its collective membrane stiffness. The ER is also a hotspot of lipid biosynthesis including sterols, glycerophospholipids, ceramides and neural storage lipids. The unfolded protein response (UPR) bears an evolutionary conserved, dual sensitivity to both protein-folding imbalances in the ER lumen and aberrant compositions of the ER membrane, referred to as lipid bilayer stress (LBS). Through transcriptional and non-transcriptional mechanisms, the UPR upregulates the protein folding capacity of the ER and balances the production of proteins and lipids to maintain a functional secretory pathway. In this review, we discuss how UPR transducers sense unfolded proteins and LBS with a particular focus on their role as guardians of the secretory pathway.
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