69 results on '"Papa FR"'
Search Results
2. Divergent allosteric control of the IRE1α endoribonuclease using kinase inhibitors
- Author
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Papa, Feroz, Oakes, Scott, Wang, L, Perera, BGK, Hari, SB, Bhhatarai, B, Backes, BJ, Seeliger, MA, Schürer, SC, Oakes, SA, Papa, FR, and Maly, DJ
- Abstract
Under endoplasmic reticulum stress, unfolded protein accumulation leads to activation of the endoplasmic reticulum transmembrane kinase/endoRNase (RNase) IRE1α. IRE1α oligomerizes, autophosphorylates and initiates splicing of XBP1 mRNA, thus triggering the
- Published
- 2012
3. Cleaved cytokeratin-18 is a mechanistically informative biomarker in idiopathic pulmonary fibrosis
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Cha, SI, Ryerson, CJ, Lee, JS, Kukreja, J, Barry, SS, Jones, KD, Elicker, BM, Kim, DS, Papa, FR, Collard, HR, and Wolters, PJ
- Abstract
Background: Stress of the endoplasmic reticulum (ER) leading to activation of the unfolded protein response (UPR) and alveolar epithelial cell (AEC) apoptosis may play a role in the pathogenesis of idiopathic pulmonary fibrosis (IPF). Our objectives were to determine whether circulating caspase-cleaved cytokeratin-18 (cCK-18) is a marker of AEC apoptosis in IPF, define the relationship of cCK-18 with activation of the UPR, and assess its utility as a diagnostic biomarker.Methods: IPF and normal lung tissues were stained with the antibody (M30) that specifically binds cCK-18. The relationship between markers of the UPR and cCK-18 was determined in AECs exposed in vitro to thapsigargin to induce ER stress. cCK-18 was measured in serum from subjects with IPF, hypersensitivity pneumonitis (HP), nonspecific interstitial pneumonia (NSIP), and control subjects.Results: cCK-18 immunoreactivity was present in AECs of IPF lung, but not in control subjects. Markers of the UPR (phosphorylated IRE-1α and spliced XBP-1) were more highly expressed in IPF type II AECs than in normal type II AECs. Phosphorylated IRE-1α and cCK-18 increased following thapsigargin-induced ER stress. Serum cCK-18 level distinguished IPF from diseased and control subjects. Serum cCK-18 was not associated with disease severity or outcome.Conclusions: cCK-18 may be a marker of AEC apoptosis and UPR activation in patients with IPF. Circulating levels of cCK-18 are increased in patients with IPF and cCK-18 may be a useful diagnostic biomarker. © 2012 Cha et al.; licensee BioMed Central Ltd.
- Published
- 2012
4. Discurso del Santo Padre Francisco con ocasión de la inauguración del año judicial del Tribunal de la Rota Romana, Sala Clementina, 29.01.2018
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Papa Francisco
- Subjects
Discurso del Santo Padre Francisco con ocasión de la inauguración del año judicial del Tribunal de la Rota Romana, Sala Clementina ,Philosophy of religion. Psychology of religion. Religion in relation to other subjects ,BL51-65 - Abstract
Discurso del Santo Padre Francisco con ocasión de la inauguración del año judicial del Tribunal de la Rota Romana, Sala Clementina
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- 2024
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5. Constitución Apostólica 'Veritatis Gaudium' sobre las universidades y facultades eclesiásticas, 8.12.2017
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Papa Francisco
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Constitución Apostólica “Veritatis Gaudium” sobre las universidades y facultades eclesiásticas ,Philosophy of religion. Psychology of religion. Religion in relation to other subjects ,BL51-65 - Abstract
Constitución Apostólica “Veritatis Gaudium” sobre las universidades y facultades eclesiásticas,
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- 2024
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6. Discurso del Santo Padre Francisco a los participantes en el curso organizado por el Tribunal de la Rota Romana, Sala Clementina, 25.11.2017
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Papa Francisco
- Subjects
Discurso del Santo Padre Francisco a los participantes en el curso organizado por el Tribunal de la Rota Romana, Sala Clementina ,Philosophy of religion. Psychology of religion. Religion in relation to other subjects ,BL51-65 - Abstract
Discurso del Santo Padre Francisco a los participantes en el curso organizado por el Tribunal de la Rota Romana, Sala Clementina, 25.11.2017
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- 2024
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7. Carta Apostólica en forma de «Motu Proprio» del Sumo Pontífice Francisco «Maiorem Hac Dilectionem» sobre el ofrecimiento de la vida, 11.07.2017
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Papa Francisco
- Subjects
Carta Apostólica en forma de «Motu Proprio» del Sumo Pontífice Francisco «Maiorem Hac Dilectionem» ,Philosophy of religion. Psychology of religion. Religion in relation to other subjects ,BL51-65 - Abstract
Carta Apostólica en forma de «Motu Proprio» del Sumo Pontífice Francisco «Maiorem Hac Dilectionem» sobre el ofrecimiento de la vida, 11.07.2017
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- 2024
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8. Francisco Constitución Apostólica Episcopalis Communio Sobre El Sínodo De Los Obispos
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Papa Francisco
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Constitución Apostólica Episcopalis Communio ,Philosophy of religion. Psychology of religion. Religion in relation to other subjects ,BL51-65 - Abstract
La comunión episcopal (Episcopalis communio), con Pedro y bajo Pedro, se manifiesta de forma peculiar en el Sínodo de los Obispos, que, instituido por Pablo VI el 15 de septiembre de 1965, constituye una de las herencias más valiosas del Concilio Vaticano II1 . Desde entonces, el Sínodo, nuevo en su institución pero antiquísimo en su inspiración, colabora eficazmente con el Romano Pontífice, según las formas por él mismo establecidas, en las cuestiones de mayor importancia, es decir aquellas que requieren especial ciencia y prudencia para el bien de toda la Iglesia. De tal manera, el Sínodo de los Obispos, «que obra en nombre de todo el episcopado católico, manifiesta, al mismo tiempo, que todos los Obispos en comunión jerárquica son partícipes de la solicitud de toda la Iglesia
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- 2024
9. Carta Apostólica en forma de «Motu Proprio» del Sumo Pontífice Francisco «Imparare a congedarsi» con la que se regula la renuncia por motivo de edad, de algunos oficios de nombramiento pontificio, 12.02.2018. Texto
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Papa Francisco
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Carta Apostólica ,Imparare a congedarsi ,Philosophy of religion. Psychology of religion. Religion in relation to other subjects ,BL51-65 - Abstract
Carta Apostólica en forma de «Motu Proprio» del Sumo Pontífice Francisco «Imparare a congedarsi» con la que se regula la renuncia por motivo de edad, de algunos oficios de nombramiento pontificio, 12.02.2018. Texto
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- 2024
10. Targeting ABL-IRE1 alpha Signaling Spares ER-Stressed Pancreatic beta Cells to Reverse Autoimmune Diabetes (vol 25, pg 883, 2017)
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Morita, S, Villalta, SA, Feldman, HC, Register, AC, Rosenthal, W, Hoffmann-Petersen, IT, Mehdizadeh, M, Ghosh, R, Wang, L, Colon-Negron, K, Meza-Acevedo, R, Backes, BJ, Maly, DJ, Bluestone, JA, and Papa, FR
- Published
- 2017
11. Targeting ABL-IRE1 alpha Signaling Spares ER- Stressed Pancreatic beta Cells to Reverse Autoimmune Diabetes
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Morita, S, Villalta, SA, Feldman, HC, Register, AC, Rosenthal, W, Hoffmann-Petersen, IT, Mehdizadeh, M, Ghosh, R, Wang, L, Colon-Negron, K, Meza-Acevedo, R, Backes, BJ, Maly, DJ, Bluestone, JA, and Papa, FR
- Published
- 2017
12. CARTA APOSTÓLICA EN FORMA DE «MOTU PROPRIO» DEL SUMO PONTÍFICE FRANCISCO «COMPETENTIAS QUASDAM DECERNERE» CON LA QUE SE MODIFICAN ALGUNAS NORMAS DEL CÓDIGO DE DERECHO CANÓNICO Y DEL CÓDIGO DE CÁNONES DE LAS IGLESIAS ORIENTALES
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Papa Francisco
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Philosophy of religion. Psychology of religion. Religion in relation to other subjects ,BL51-65 - Abstract
CARTA APOSTÓLICA EN FORMA DE «MOTU PROPRIO» DEL SUMO PONTÍFICE FRANCISCO «COMPETENTIAS QUASDAM DECERNERE» CON LA QUE SE MODIFICAN ALGUNAS NORMAS DEL CÓDIGO DE DERECHO CANÓNICO Y DEL CÓDIGO DE CÁNONES DE LAS IGLESIAS ORIENTALES
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- 2022
13. CARTA APOSTÓLICA EN FORMA DE «MOTU PROPRIO» DEL SUMO PONTÍFICE FRANCISCO «TRADITIONIS CUSTODES» SOBRE EL USO DE LA LITURGIA ROMANA ANTES DE LA REFORMA DE 1970
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Papa Francisco
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Philosophy of religion. Psychology of religion. Religion in relation to other subjects ,BL51-65 - Abstract
CARTA APOSTÓLICA EN FORMA DE «MOTU PROPRIO» DEL SUMO PONTÍFICE FRANCISCO «TRADITIONIS CUSTODES» SOBRE EL USO DE LA LITURGIA ROMANA ANTES DE LA REFORMA DE 1970
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- 2022
14. Documentación
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Papa Francisco
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Philosophy of religion. Psychology of religion. Religion in relation to other subjects ,BL51-65 - Abstract
Documentación
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- 2022
15. SUMMUS PONTIFEX FRANCISCUS LITTERAE APOSTOLICAE MOTU PROPRIO DATAE RECOGNITUM LIBRUM VI quibus can. 695 §1, Codicis Iuris Canonici immutatur
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Papa Francisco
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Philosophy of religion. Psychology of religion. Religion in relation to other subjects ,BL51-65 - Abstract
SUMMUS PONTIFEX FRANCISCUS LITTERAE APOSTOLICAE MOTU PROPRIO DATAE RECOGNITUM LIBRUM VI quibus can. 695 §1, Codicis Iuris Canonici immutatur
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- 2022
16. Encuentro mundial de los movimientos populares en el Vaticano (27 al 29–X–2014)
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Papa Francisco
- Subjects
Social Sciences - Published
- 2014
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17. Extracto del Discurso del Papa a la comunidad de los escritores de 'La Civiltà Cattolica'
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Papa Francisco
- Subjects
Social Sciences - Published
- 2013
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18. Surgical treatment of gingival overgrowth with 10 years of follow-up
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Ballini Andrea, Scattarella Adele, Crincoli Vito, Carlaio Roberto, Papa Francesco, Perillo Letizia, Romanazzo Teodoro, Bux Maria, Nardi Gianna, Dituri Angela, Cantore Stefania, Pettini Francesco, and Grassi Felice
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Specialties of internal medicine ,RC581-951 - Abstract
Abstract Background In some pathological conditions, gingivitis caused by plaque accumulation can be more severe, with the result of an overgrowth. Nevertheless, the overgrowth involves the gingival margin with extension to the inter-dental papilla. The lesion may involve the inter-proximal spaces, and become so extensive that the teeth are displaced and their crowns covered. Severe overgrowth may lead to impairment in aesthetic and masticatory functions, requiring surgical excision of the excessive tissue. Aim of this study is to describe an operative protocol for the surgical treatment of localized gingival overgrowth analyzing the surgical technique, times and follow-up. Methods A total of 20 patients were enrolled and underwent initial, non surgical, periodontal treatment and training sessions on home oral hygiene training. The treatment plan involved radical exeresis of the mass followed by positioning of an autograft of connective tissue and keratinized gingiva. Results During 10 years of follow-up, all the grafts appeared well vascularized, aesthetically satisfactory, and without relapse. Conclusions Periodontal examinations, surgical procedures, and dental hygiene with follow-up are an essential part of the treatment protocol. However, additional effort is needed from the patient. Hopefully, the final treatment result makes it all worthwhile.
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- 2010
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19. BCL-2 Modulates IRE1α Activation to Attenuate Endoplasmic Reticulum Stress and Pulmonary Fibrosis.
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Le Saux CJ, Ho TC, Brumwell AM, Kathiriya JJ, Wei Y, Hughes JB, Garakani K, Atabai K, Auyeung VC, Papa FR, and Chapman HA
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- Mice, Animals, Endoribonucleases, Protein Serine-Threonine Kinases, Endoplasmic Reticulum Stress, Mice, Knockout, Collagen metabolism, Bleomycin pharmacology, Pulmonary Fibrosis metabolism, Aniline Compounds, Sulfonamides
- Abstract
BCL-2 family members are known to be implicated in survival in numerous biological settings. Here, we provide evidence that in injury and repair processes in lungs, BCL-2 mainly acts to attenuate endoplasmic reticulum (ER) stress and limit extracellular matrix accumulation. Days after an intratracheal bleomycin challenge, mice lose a fraction of their alveolar type II epithelium from terminal ER stress driven by activation of the critical ER sensor and stress effector IRE1α. This fraction is dramatically increased by BCL-2 inhibition, because IRE1α activation is dependent on its physical association with the BCL-2-proapoptotic family member BAX, and we found BCL-2 to disrupt this association in vitro . In vivo , navitoclax (a BCL-2/BCL-xL inhibitor) given 15-21 days after bleomycin challenge evoked strong activation of IRE-1α in mesenchymal cells and markers of ER stress, but not apoptosis. Remarkably, after BCL-2 inhibition, bleomycin-exposed mice demonstrated persistent collagen accumulation at Day 42, compared with resolution in controls. Enhanced fibrosis proved to be due to the RNAase activity of IRE1α downregulating MRC2 mRNA and protein, a mediator of collagen turnover. The critical role of MRC2 was confirmed in precision-cut lung slice cultures of Day-42 lungs from bleomycin-exposed wild-type and MRC2 null mice. Soluble and tissue collagen accumulated in precision-cut lung slice cultures from navitoclax-treated, bleomycin-challenged mice compared with controls, in a manner nearly identical to that of challenged but untreated MRC2 null mice. Thus, apart from mitochondrial-based antiapoptosis, BCL-2 functions to attenuate ER stress responses, fostering tissue homeostasis and injury repair.
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- 2024
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20. Deletion of the Unfolded Protein Response Transducer IRE1α Is Detrimental to Aging Photoreceptors and to ER Stress-Mediated Retinal Degeneration.
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Massoudi D, Gorman S, Kuo YM, Iwawaki T, Oakes SA, Papa FR, and Gould DB
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- Animals, Mice, Aging, Endoribonucleases genetics, Endoribonucleases metabolism, Protein Serine-Threonine Kinases genetics, Protein Serine-Threonine Kinases metabolism, Rhodopsin genetics, Rhodopsin metabolism, Unfolded Protein Response, Endoplasmic Reticulum Stress, Retinal Degeneration metabolism, Retinitis Pigmentosa
- Abstract
Purpose: The unfolded protein response (UPR) is triggered when the protein folding capacity of the endoplasmic reticulum (ER) is overwhelmed and misfolded proteins accumulate in the ER, a condition referred to as ER stress. IRE1α is an ER-resident protein that plays major roles in orchestrating the UPR. Several lines of evidence implicate the UPR and its transducers in neurodegenerative diseases, including retinitis pigmentosa (RP), a group of inherited diseases that cause progressive dysfunction and loss of rod and cone photoreceptors. This study evaluated the contribution of IRE1α to photoreceptor development, homeostasis, and degeneration., Methods: We used a conditional gene targeting strategy to selectively inactivate Ire1α in mouse rod photoreceptors. We used a combination of optical coherence tomography (OCT) imaging, histology, and electroretinography (ERG) to assess longitudinally the effect of IRE1α deficiency in retinal development and function. Furthermore, we evaluated the IRE1α-deficient retina responses to tunicamycin-induced ER stress and in the context of RP caused by the rhodopsin mutation RhoP23H., Results: OCT imaging, histology, and ERG analyses did not reveal abnormalities in IRE1α-deficient retinas up to 3 months old. However, by 6 months of age, the Ire1α mutant animals showed reduced outer nuclear layer thickness and deficits in retinal function. Furthermore, conditional inactivation of Ire1α in rod photoreceptors accelerated retinal degeneration caused by the RhoP23H mutation., Conclusions: These data suggest that IRE1α is dispensable for photoreceptor development but important for photoreceptor homeostasis in aging retinas and for protecting against ER stress-mediated photoreceptor degeneration.
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- 2023
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21. IRE1α drives lung epithelial progenitor dysfunction to establish a niche for pulmonary fibrosis.
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Auyeung VC, Downey MS, Thamsen M, Wenger TA, Backes BJ, Sheppard D, and Papa FR
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- Apoptosis physiology, Endoplasmic Reticulum Stress physiology, Humans, Lung metabolism, Protein Serine-Threonine Kinases genetics, Endoribonucleases metabolism, Idiopathic Pulmonary Fibrosis metabolism
- Abstract
After lung injury, damage-associated transient progenitors (DATPs) emerge, representing a transitional state between injured epithelial cells and newly regenerated alveoli. DATPs express profibrotic genes, suggesting that they might promote idiopathic pulmonary fibrosis (IPF). However, the molecular pathways that induce and/or maintain DATPs are incompletely understood. Here we show that the bifunctional kinase/RNase-IRE1α-a central mediator of the unfolded protein response (UPR) to endoplasmic reticulum (ER) stress is a critical promoter of DATP abundance and function. Administration of a nanomolar-potent, monoselective kinase inhibitor of IRE1α (KIRA8)-or conditional epithelial IRE1α gene knockout-both reduce DATP cell number and fibrosis in the bleomycin model, indicating that IRE1α cell-autonomously promotes transition into the DATP state. IRE1α enhances the profibrotic phenotype of DATPs since KIRA8 decreases expression of integrin αvβ6, a key activator of transforming growth factor β (TGF-β) in pulmonary fibrosis, corresponding to decreased TGF-β-induced gene expression in the epithelium and decreased collagen accumulation around DATPs. Furthermore, IRE1α regulates DNA damage response (DDR) signaling, previously shown to promote the DATP phenotype, as IRE1α loss-of-function decreases H2AX phosphorylation, Cdkn1a (p21) expression, and DDR-associated secretory gene expression. Finally, KIRA8 treatment increases the differentiation of Krt19
CreERT2 -lineage-traced DATPs into type 1 alveolar epithelial cells after bleomycin injury, indicating that relief from IRE1α signaling enables DATPs to exit the transitional state. Thus, IRE1α coordinates a network of stress pathways that conspire to entrap injured cells in the DATP state. Pharmacological blockade of IRE1α signaling helps resolve the DATP state, thereby ameliorating fibrosis and promoting salutary lung regeneration.- Published
- 2022
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22. ATP-competitive partial antagonists of the IRE1α RNase segregate outputs of the UPR.
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Feldman HC, Ghosh R, Auyeung VC, Mueller JL, Kim JH, Potter ZE, Vidadala VN, Perera BGK, Olivier A, Backes BJ, Zikherman J, Papa FR, and Maly DJ
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- Adenosine Triphosphate chemistry, Endoribonucleases metabolism, Humans, Models, Molecular, Molecular Structure, Protein Kinase Inhibitors chemistry, Protein Serine-Threonine Kinases metabolism, Protein Unfolding drug effects, Adenosine Triphosphate pharmacology, Endoribonucleases antagonists & inhibitors, Protein Kinase Inhibitors pharmacology, Protein Serine-Threonine Kinases antagonists & inhibitors
- Abstract
The unfolded protein response (UPR) homeostatically matches endoplasmic reticulum (ER) protein-folding capacity to cellular secretory needs. However, under high or chronic ER stress, the UPR triggers apoptosis. This cell fate dichotomy is promoted by differential activation of the ER transmembrane kinase/endoribonuclease (RNase) IRE1α. We previously found that the RNase of IRE1α can be either fully activated or inactivated by ATP-competitive kinase inhibitors. Here we developed kinase inhibitors, partial antagonists of IRE1α RNase (PAIRs), that partially antagonize the IRE1α RNase at full occupancy. Biochemical and structural studies show that PAIRs promote partial RNase antagonism by intermediately displacing the helix αC in the IRE1α kinase domain. In insulin-producing β-cells, PAIRs permit adaptive splicing of Xbp1 mRNA while quelling destructive ER mRNA endonucleolytic decay and apoptosis. By preserving Xbp1 mRNA splicing, PAIRs allow B cells to differentiate into immunoglobulin-producing plasma cells. Thus, an intermediate RNase-inhibitory 'sweet spot', achieved by PAIR-bound IRE1α, captures a desirable conformation for drugging this master UPR sensor/effector., (© 2021. The Author(s), under exclusive licence to Springer Nature America, Inc.)
- Published
- 2021
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23. Targeting Adaptive IRE1α Signaling and PLK2 in Multiple Myeloma: Possible Anti-Tumor Mechanisms of KIRA8 and Nilotinib.
- Author
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Yamashita Y, Morita S, Hosoi H, Kobata H, Kishimoto S, Ishibashi T, Mishima H, Kinoshita A, Backes BJ, Yoshiura KI, Papa FR, Sonoki T, and Tamura S
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- Adult, Aged, Apoptosis, Biomarkers, Tumor genetics, Biomarkers, Tumor metabolism, Cell Movement, Cell Proliferation, Cross-Sectional Studies, Female, Follow-Up Studies, Humans, Male, Middle Aged, Multiple Myeloma pathology, Prognosis, Pyrazines administration & dosage, Pyrimidines administration & dosage, Retrospective Studies, Tumor Cells, Cultured, Antineoplastic Combined Chemotherapy Protocols pharmacology, Endoribonucleases antagonists & inhibitors, Gene Expression Regulation, Neoplastic drug effects, Molecular Targeted Therapy, Multiple Myeloma drug therapy, Protein Serine-Threonine Kinases antagonists & inhibitors
- Abstract
Background: Inositol-requiring enzyme 1α (IRE1α), along with protein kinase R-like endoplasmic reticulum kinase (PERK), is a principal regulator of the unfolded protein response (UPR). Recently, the 'mono'-specific IRE1α inhibitor, kinase-inhibiting RNase attenuator 6 (KIRA6), demonstrated a promising effect against multiple myeloma (MM). Side-stepping the clinical translation, a detailed UPR phenotype in patients with MM and the mechanisms of how KIRA8 works in MM remains unclear., Methods: We characterized UPR phenotypes in the bone marrow of patients with newly diagnosed MM. Then, in human MM cells we analyzed the possible anti-tumor mechanisms of KIRA8 and a Food and Drug Administration (FDA)-approved drug, nilotinib, which we recently identified as having a strong inhibitory effect against IRE1α activity. Finally, we performed an RNA-sequence analysis to detect key IRE1α-related molecules against MM., Results: We illustrated the dominant induction of adaptive UPR markers under IRE1α over the PERK pathway in patients with MM. In human MM cells, KIRA8 decreased cell viability and induced apoptosis, along with the induction of C/EBP homologous protein (CHOP); its combination with bortezomib exhibited more anti-myeloma effects than KIRA8 alone. Nilotinib exerted a similar effect compared with KIRA8. RNA-sequencing identified Polo-like kinase 2 ( PLK2 ) as a KIRA8-suppressed gene. Specifically, the IRE1α overexpression induced PLK2 expression, which was decreased by KIRA8. KIRA8 and PLK2 inhibition exerted anti-myeloma effects with apoptosis induction and the regulation of cell proliferation. Finally, PLK2 was pathologically confirmed to be highly expressed in patients with MM., Conclusion: Dominant activation of adaptive IRE1α was established in patients with MM. Both KIRA8 and nilotinib exhibited anti-myeloma effects, which were enhanced by bortezomib. Adaptive IRE1α signaling and PLK2 could be potential therapeutic targets and biomarkers in MM.
- Published
- 2020
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24. Nicotinic acetylcholine receptor signaling regulates inositol-requiring enzyme 1α activation to protect β-cells against terminal unfolded protein response under irremediable endoplasmic reticulum stress.
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Ishibashi T, Morita S, Kishimoto S, Uraki S, Takeshima K, Furukawa Y, Inaba H, Ariyasu H, Iwakura H, Furuta H, Nishi M, Papa FR, and Akamizu T
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- Animals, Apoptosis physiology, Cell Line, Humans, Insulin-Secreting Cells metabolism, Protective Agents pharmacology, Rats, Endoplasmic Reticulum Stress physiology, Endoribonucleases metabolism, Protein Serine-Threonine Kinases metabolism, Receptors, Nicotinic metabolism, Signal Transduction physiology, Unfolded Protein Response physiology
- Abstract
Aims/introduction: Under irremediable endoplasmic reticulum (ER) stress, hyperactivated inositol-requiring enzyme 1α (IRE1α) triggers the terminal unfolded protein response (T-UPR), causing crucial cell dysfunction and apoptosis. We hypothesized that nicotinic acetylcholine receptor (nAChR) signaling regulates IRE1α activation to protect β-cells from the T-UPR under ER stress., Materials and Methods: The effects of nicotine on IRE1α activation and key T-UPR markers, thioredoxin-interacting protein and insulin/proinsulin, were analyzed by real-time polymerase chain reaction and western blotting in rat INS-1 and human EndoC-βH1 β-cell lines. Doxycycline-inducible IRE1α overexpression or ER stress agents were used to induce IRE1α activation. An α7 subunit-specific nAChR agonist (PNU-282987) and small interfering ribonucleic acid for α7 subunit-specific nAChR were used to modulate nAChR signaling., Results: Nicotine inhibits the increase in thioredoxin-interacting protein and the decrease in insulin 1/proinsulin expression levels induced by either forced IRE1α hyperactivation or ER stress agents. Nicotine attenuated X-box-binding protein-1 messenger ribonucleic acid site-specific splicing and IRE1α autophosphorylation induced by ER stress. Furthermore, PNU-282987 attenuated T-UPR induction by either forced IRE1α activation or ER stress agents. The effects of nicotine on attenuating thioredoxin-interacting protein and preserving insulin 1 expression levels were attenuated by pharmacological and genetic inhibition of α7 nAChR. Finally, nicotine suppressed apoptosis induced by either forced IRE1α activation or ER stress agents., Conclusions: Our findings suggest that nAChR signaling regulates IRE1α activation to protect β-cells from the T-UPR and apoptosis under ER stress partly through α7 nAChR. Targeting nAChR signaling to inhibit the T-UPR cascade may therefore hold therapeutic promise by thwarting β-cell death in diabetes., (© 2020 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.)
- Published
- 2020
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25. Development of a Chemical Toolset for Studying the Paralog-Specific Function of IRE1.
- Author
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Feldman HC, Vidadala VN, Potter ZE, Papa FR, Backes BJ, and Maly DJ
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- Allosteric Regulation, Animals, Endoplasmic Reticulum Stress, Endoribonucleases metabolism, Humans, Protein Serine-Threonine Kinases metabolism, Ribonucleases metabolism, Endoribonucleases physiology, Protein Serine-Threonine Kinases physiology
- Abstract
The dual kinase endoribonuclease IRE1 is a master regulator of cell fate decisions in cells experiencing endoplasmic reticulum (ER) stress. In mammalian cells, there are two paralogs of IRE1: IRE1α and IRE1β. While IRE1α has been extensively studied, much less is understood about IRE1β and its role in signaling. In addition, whether the regulation of IRE1β's enzymatic activities varies compared to IRE1α is not known. Here, we show that the RNase domain of IRE1β is enzymatically active and capable of cleaving an XBP1 RNA mini-substrate in vitro . Using ATP-competitive inhibitors, we find that, like IRE1α, there is an allosteric relationship between the kinase and RNase domains of IRE1β. This allowed us to develop a novel toolset of both paralog specific and dual-IRE1α/β kinase inhibitors that attenuate RNase activity (KIRAs). Using sequence alignments of IRE1α and IRE1β, we propose a model for paralog-selective inhibition through interactions with nonconserved residues that differentiate the ATP-binding pockets of IRE1α and IRE1β.
- Published
- 2019
- Full Text
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26. Parallel Signaling through IRE1α and PERK Regulates Pancreatic Neuroendocrine Tumor Growth and Survival.
- Author
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Moore PC, Qi JY, Thamsen M, Ghosh R, Peng J, Gliedt MJ, Meza-Acevedo R, Warren RE, Hiniker A, Kim GE, Maly DJ, Backes BJ, Papa FR, and Oakes SA
- Subjects
- Adenine analogs & derivatives, Adenine pharmacology, Adenine therapeutic use, Animals, Cell Line, Tumor, Cell Proliferation drug effects, Cell Survival drug effects, Disease Models, Animal, Endoplasmic Reticulum Stress drug effects, Endoribonucleases metabolism, Female, Humans, Indoles pharmacology, Indoles therapeutic use, Mice, Mice, Transgenic, Neuroendocrine Tumors genetics, Neuroendocrine Tumors pathology, Pancreatic Neoplasms genetics, Pancreatic Neoplasms pathology, Protein Kinase Inhibitors therapeutic use, Protein Serine-Threonine Kinases metabolism, Signal Transduction drug effects, Unfolded Protein Response drug effects, Xenograft Model Antitumor Assays, eIF-2 Kinase metabolism, Endoribonucleases antagonists & inhibitors, Neuroendocrine Tumors drug therapy, Pancreatic Neoplasms drug therapy, Protein Kinase Inhibitors pharmacology, Protein Serine-Threonine Kinases antagonists & inhibitors, eIF-2 Kinase antagonists & inhibitors
- Abstract
Master regulators of the unfolded protein response (UPR), IRE1α and PERK, promote adaptation or apoptosis depending on the level of endoplasmic reticulum (ER) stress. Although the UPR is activated in many cancers, its effects on tumor growth remain unclear. Derived from endocrine cells, pancreatic neuroendocrine tumors (PanNET) universally hypersecrete one or more peptide hormones, likely sensitizing these cells to high ER protein-folding stress. To assess whether targeting the UPR is a viable therapeutic strategy, we analyzed human PanNET samples and found evidence of elevated ER stress and UPR activation. Genetic and pharmacologic modulation of IRE1α and PERK in cultured cells, xenograft, and spontaneous genetic (RIP-Tag2) mouse models of PanNETs revealed that UPR signaling was optimized for adaptation and that inhibiting either IRE1α or PERK led to hyperactivation and apoptotic signaling through the reciprocal arm, thereby halting tumor growth and survival. These results provide a strong rationale for therapeutically targeting the UPR in PanNETs and other cancers with elevated ER stress. SIGNIFICANCE: The UPR is upregulated in pancreatic neuroendocrine tumors and its inhibition significantly reduces tumor growth in preclinical models, providing strong rationale for targeting the UPR in these cancers., (©2019 American Association for Cancer Research.)
- Published
- 2019
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27. Small Molecules to Improve ER Proteostasis in Disease.
- Author
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Gonzalez-Teuber V, Albert-Gasco H, Auyeung VC, Papa FR, Mallucci GR, and Hetz C
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- Animals, Endoplasmic Reticulum metabolism, Humans, Metabolic Diseases metabolism, Neoplasms metabolism, Neurodegenerative Diseases metabolism, Proteostasis drug effects, Unfolded Protein Response drug effects, Endoplasmic Reticulum drug effects, Metabolic Diseases drug therapy, Neoplasms drug therapy, Neurodegenerative Diseases drug therapy
- Abstract
Abnormally high levels of misfolded proteins in the endoplasmic reticulum (ER) lumen result in a stress state that contributes to the progression of several pathological conditions including diabetes, cancer, neurodegeneration, and immune dysregulation. ER stress triggers a dynamic signaling pathway known as the unfolded protein response (UPR). The UPR enforces adaptive or cell death programs by integrating information about the intensity and duration of the stress stimuli. Thus, depending on the disease context, ER stress signaling can be beneficial or detrimental. We discuss current efforts to develop small molecules to target distinct components of the UPR, and their possible applications in treating human disease, focusing on neurodegenerative diseases, metabolic disorders, and cancer., (Copyright © 2019. Published by Elsevier Ltd.)
- Published
- 2019
- Full Text
- View/download PDF
28. Endoplasmic reticulum stress, degeneration of pancreatic islet β-cells, and therapeutic modulation of the unfolded protein response in diabetes.
- Author
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Ghosh R, Colon-Negron K, and Papa FR
- Subjects
- Animals, Humans, Diabetes Mellitus metabolism, Endoplasmic Reticulum metabolism, Endoplasmic Reticulum Stress, Insulin-Secreting Cells metabolism, Protein Serine-Threonine Kinases metabolism, Unfolded Protein Response
- Abstract
Background: Myriad challenges to the proper folding and structural maturation of secretory pathway client proteins in the endoplasmic reticulum (ER) - a condition referred to as "ER stress" - activate intracellular signaling pathways termed the unfolded protein response (UPR)., Scope of Review: Through executing transcriptional and translational programs the UPR restores homeostasis in those cells experiencing manageable levels of ER stress. But the UPR also actively triggers cell degeneration and apoptosis in those cells that are encountering ER stress levels that exceed irremediable thresholds. Thus, UPR outputs are "double-edged". In pancreatic islet β-cells, numerous genetic mutations affecting the balance between these opposing UPR functions cause diabetes mellitus in both rodents and humans, amply demonstrating the principle that the UPR is critical for the proper functioning and survival of the cell., Major Conclusions: Specifically, we have found that the UPR master regulator IRE1α kinase/endoribonuclease (RNase) triggers apoptosis, β-cell degeneration, and diabetes, when ER stress reaches critical levels. Based on these mechanistic findings, we find that novel small molecule compounds that inhibit IRE1α during such "terminal" UPR signaling can spare ER stressed β-cells from death, perhaps affording future opportunities to test new drug candidates for disease modification in patients suffering from diabetes., (Copyright © 2019. Published by Elsevier GmbH.)
- Published
- 2019
- Full Text
- View/download PDF
29. Chaperone-mediated reflux of secretory proteins to the cytosol during endoplasmic reticulum stress.
- Author
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Igbaria A, Merksamer PI, Trusina A, Tilahun F, Johnson JR, Brandman O, Krogan NJ, Weissman JS, and Papa FR
- Subjects
- Endoplasmic Reticulum-Associated Degradation physiology, Homeostasis physiology, Oxidation-Reduction, Protein Folding, Saccharomyces cerevisiae metabolism, Ubiquitin-Protein Ligases metabolism, Cytosol metabolism, Endoplasmic Reticulum metabolism, Endoplasmic Reticulum Stress physiology, Molecular Chaperones metabolism
- Abstract
Diverse perturbations to endoplasmic reticulum (ER) functions compromise the proper folding and structural maturation of secretory proteins. To study secretory pathway physiology during such "ER stress," we employed an ER-targeted, redox-responsive, green fluorescent protein-eroGFP-that reports on ambient changes in oxidizing potential. Here we find that diverse ER stress regimes cause properly folded, ER-resident eroGFP (and other ER luminal proteins) to "reflux" back to the reducing environment of the cytosol as intact, folded proteins. By utilizing eroGFP in a comprehensive genetic screen in Saccharomyces cerevisiae , we show that ER protein reflux during ER stress requires specific chaperones and cochaperones residing in both the ER and the cytosol. Chaperone-mediated ER protein reflux does not require E3 ligase activity, and proceeds even more vigorously when these ER-associated degradation (ERAD) factors are crippled, suggesting that reflux may work in parallel with ERAD. In summary, chaperone-mediated ER protein reflux may be a conserved protein quality control process that evolved to maintain secretory pathway homeostasis during ER protein-folding stress., Competing Interests: The authors declare no conflict of interest.
- Published
- 2019
- Full Text
- View/download PDF
30. Small molecule inhibition of IRE1α kinase/RNase has anti-fibrotic effects in the lung.
- Author
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Thamsen M, Ghosh R, Auyeung VC, Brumwell A, Chapman HA, Backes BJ, Perara G, Maly DJ, Sheppard D, and Papa FR
- Subjects
- Alveolar Epithelial Cells metabolism, Alveolar Epithelial Cells pathology, Animals, Apoptosis drug effects, Cell Line, Endoplasmic Reticulum Stress drug effects, Fibrosis metabolism, Fibrosis pathology, Lung metabolism, Lung pathology, Mice, Protein Kinase Inhibitors therapeutic use, Unfolded Protein Response drug effects, Alveolar Epithelial Cells drug effects, Endoribonucleases antagonists & inhibitors, Fibrosis drug therapy, Lung drug effects, Protein Kinase Inhibitors pharmacology, Protein Serine-Threonine Kinases antagonists & inhibitors
- Abstract
Endoplasmic reticulum stress (ER stress) has been implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF), a disease of progressive fibrosis and respiratory failure. ER stress activates a signaling pathway called the unfolded protein response (UPR) that either restores homeostasis or promotes apoptosis. The bifunctional kinase/RNase IRE1α is a UPR sensor/effector that promotes apoptosis if ER stress remains high and irremediable (i.e., a "terminal" UPR). Using multiple small molecule inhibitors against IRE1α, we show that ER stress-induced apoptosis of murine alveolar epithelial cells can be mitigated in vitro. In vivo, we show that bleomycin exposure to murine lungs causes early ER stress to activate IRE1α and the terminal UPR prior to development of pulmonary fibrosis. Small-molecule IRE1α kinase-inhibiting RNase attenuators (KIRAs) that we developed were used to evaluate the contribution of IRE1α activation to bleomycin-induced pulmonary fibrosis. One such KIRA-KIRA7-provided systemically to mice at the time of bleomycin exposure decreases terminal UPR signaling and prevents lung fibrosis. Administration of KIRA7 14 days after bleomycin exposure even promoted the reversal of established fibrosis. Finally, we show that KIRA8, a nanomolar-potent, monoselective KIRA compound derived from a completely different scaffold than KIRA7, likewise promoted reversal of established fibrosis. These results demonstrate that IRE1α may be a promising target in pulmonary fibrosis and that kinase inhibitors of IRE1α may eventually be developed into efficacious anti-fibrotic drugs., Competing Interests: The authors have declared that no competing interests exist.
- Published
- 2019
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- View/download PDF
31. The Unfolded Protein Response and Cell Fate Control.
- Author
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Hetz C and Papa FR
- Subjects
- Activating Transcription Factor 6 metabolism, Animals, Apoptosis, Endoplasmic Reticulum metabolism, Endoplasmic Reticulum Stress, Endoribonucleases metabolism, Homeostasis, Humans, Models, Biological, Protein Folding, Protein Serine-Threonine Kinases metabolism, Secretory Pathway physiology, Signal Transduction, eIF-2 Kinase metabolism, Cell Lineage physiology, Unfolded Protein Response physiology
- Abstract
The secretory capacity of a cell is constantly challenged by physiological demands and pathological perturbations. To adjust and match the protein-folding capacity of the endoplasmic reticulum (ER) to changing secretory needs, cells employ a dynamic intracellular signaling pathway known as the unfolded protein response (UPR). Homeostatic activation of the UPR enforces adaptive programs that modulate and augment key aspects of the entire secretory pathway, whereas maladaptive UPR outputs trigger apoptosis. Here, we discuss recent advances into how the UPR integrates information about the intensity and duration of ER stress stimuli in order to control cell fate. These findings are timely and significant because they inform an evolving mechanistic understanding of a wide variety of human diseases, including diabetes mellitus, neurodegeneration, and cancer, thus opening up the potential for new therapeutic modalities to treat these diverse diseases., (Copyright © 2017 Elsevier Inc. All rights reserved.)
- Published
- 2018
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- View/download PDF
32. Targeting ABL-IRE1α Signaling Spares ER-Stressed Pancreatic β Cells to Reverse Autoimmune Diabetes.
- Author
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Morita S, Villalta SA, Feldman HC, Register AC, Rosenthal W, Hoffmann-Petersen IT, Mehdizadeh M, Ghosh R, Wang L, Colon-Negron K, Meza-Acevedo R, Backes BJ, Maly DJ, Bluestone JA, and Papa FR
- Published
- 2017
- Full Text
- View/download PDF
33. Structural and Functional Analysis of the Allosteric Inhibition of IRE1α with ATP-Competitive Ligands.
- Author
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Feldman HC, Tong M, Wang L, Meza-Acevedo R, Gobillot TA, Lebedev I, Gliedt MJ, Hari SB, Mitra AK, Backes BJ, Papa FR, Seeliger MA, and Maly DJ
- Subjects
- Allosteric Regulation, Binding, Competitive, Endoplasmic Reticulum Stress, Endoribonucleases antagonists & inhibitors, Endoribonucleases chemistry, Humans, Ligands, Molecular Structure, Protein Kinase Inhibitors pharmacology, Protein Serine-Threonine Kinases antagonists & inhibitors, Protein Serine-Threonine Kinases chemistry, Ribonucleases antagonists & inhibitors, Structure-Activity Relationship, Adenosine Triphosphate metabolism, Endoribonucleases metabolism, Protein Serine-Threonine Kinases metabolism
- Abstract
The accumulation of unfolded proteins under endoplasmic reticulum (ER) stress leads to the activation of the multidomain protein sensor IRE1α as part of the unfolded protein response (UPR). Clustering of IRE1α lumenal domains in the presence of unfolded proteins promotes kinase trans-autophosphorylation in the cytosol and subsequent RNase domain activation. Interestingly, there is an allosteric relationship between the kinase and RNase domains of IRE1α, which allows ATP-competitive inhibitors to modulate the activity of the RNase domain. Here, we use kinase inhibitors to study how ATP-binding site conformation affects the activity of the RNase domain of IRE1α. We find that diverse ATP-competitive inhibitors of IRE1α promote dimerization and activation of RNase activity despite blocking kinase autophosphorylation. In contrast, a subset of ATP-competitive ligands, which we call KIRAs, allosterically inactivate the RNase domain through the kinase domain by stabilizing monomeric IRE1α. Further insight into how ATP-competitive inhibitors are able to divergently modulate the RNase domain through the kinase domain was gained by obtaining the first structure of apo human IRE1α in the RNase active back-to-back dimer conformation. Comparison of this structure with other existing structures of IRE1α and integration of our extensive structure activity relationship (SAR) data has led us to formulate a model to rationalize how ATP-binding site ligands are able to control the IRE1α oligomeric state and subsequent RNase domain activity., Competing Interests: Bradley J. Backes, Feroz R. Papa, and Dustin J. Maly are scientific co-founders, equity holders, and paid consultants for OptiKira L. L. C.
- Published
- 2016
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34. Correction: X-Box Binding Protein 1 (XBP1s) Is a Critical Determinant of Pseudomonas aeruginosa Homoserine Lactone-Mediated Apoptosis.
- Author
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Valentine CD, Anderson MO, Papa FR, and Haggie PM
- Abstract
[This corrects the article DOI: 10.1371/journal.ppat.1003576.].
- Published
- 2016
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35. COPA mutations impair ER-Golgi transport and cause hereditary autoimmune-mediated lung disease and arthritis.
- Author
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Watkin LB, Jessen B, Wiszniewski W, Vece TJ, Jan M, Sha Y, Thamsen M, Santos-Cortez RL, Lee K, Gambin T, Forbes LR, Law CS, Stray-Pedersen A, Cheng MH, Mace EM, Anderson MS, Liu D, Tang LF, Nicholas SK, Nahmod K, Makedonas G, Canter DL, Kwok PY, Hicks J, Jones KD, Penney S, Jhangiani SN, Rosenblum MD, Dell SD, Waterfield MR, Papa FR, Muzny DM, Zaitlen N, Leal SM, Gonzaga-Jauregui C, Boerwinkle E, Eissa NT, Gibbs RA, Lupski JR, Orange JS, and Shum AK
- Subjects
- Amino Acid Sequence, Child, Preschool, Endoplasmic Reticulum metabolism, Endoplasmic Reticulum Stress, Female, Genetic Association Studies, Genetic Predisposition to Disease, HEK293 Cells, Humans, Infant, Lod Score, Male, Molecular Sequence Data, Pedigree, Protein Transport, Arthritis genetics, Autoimmune Diseases genetics, Coatomer Protein genetics, Golgi Apparatus metabolism, Lung Diseases, Interstitial genetics
- Abstract
Unbiased genetic studies have uncovered surprising molecular mechanisms in human cellular immunity and autoimmunity. We performed whole-exome sequencing and targeted sequencing in five families with an apparent mendelian syndrome of autoimmunity characterized by high-titer autoantibodies, inflammatory arthritis and interstitial lung disease. We identified four unique deleterious variants in the COPA gene (encoding coatomer subunit α) affecting the same functional domain. Hypothesizing that mutant COPA leads to defective intracellular transport via coat protein complex I (COPI), we show that COPA variants impair binding to proteins targeted for retrograde Golgi-to-ER transport. Additionally, expression of mutant COPA results in ER stress and the upregulation of cytokines priming for a T helper type 17 (TH17) response. Patient-derived CD4(+) T cells also demonstrate significant skewing toward a TH17 phenotype that is implicated in autoimmunity. Our findings uncover an unexpected molecular link between a vesicular transport protein and a syndrome of autoimmunity manifested by lung and joint disease.
- Published
- 2015
- Full Text
- View/download PDF
36. The role of endoplasmic reticulum stress in human pathology.
- Author
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Oakes SA and Papa FR
- Subjects
- Animals, Endoplasmic Reticulum genetics, Endoplasmic Reticulum metabolism, Endoplasmic Reticulum Stress genetics, Humans, Unfolded Protein Response, Endoplasmic Reticulum pathology, Endoplasmic Reticulum Stress physiology
- Abstract
Numerous genetic and environmental insults impede the ability of cells to properly fold and posttranslationally modify secretory and transmembrane proteins in the endoplasmic reticulum (ER), leading to a buildup of misfolded proteins in this organelle--a condition called ER stress. ER-stressed cells must rapidly restore protein-folding capacity to match protein-folding demand if they are to survive. In the presence of high levels of misfolded proteins in the ER, an intracellular signaling pathway called the unfolded protein response (UPR) induces a set of transcriptional and translational events that restore ER homeostasis. However, if ER stress persists chronically at high levels, a terminal UPR program ensures that cells commit to self-destruction. Chronic ER stress and defects in UPR signaling are emerging as key contributors to a growing list of human diseases, including diabetes, neurodegeneration, and cancer. Hence, there is much interest in targeting components of the UPR as a therapeutic strategy to combat these ER stress-associated pathologies.
- Published
- 2015
- Full Text
- View/download PDF
37. Druggable sensors of the unfolded protein response.
- Author
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Maly DJ and Papa FR
- Subjects
- Animals, Endoplasmic Reticulum chemistry, Endoplasmic Reticulum drug effects, Endoplasmic Reticulum enzymology, Endoplasmic Reticulum Stress, Homeostasis, Humans, Signal Transduction, eIF-2 Kinase genetics, Endoplasmic Reticulum metabolism, Endoribonucleases metabolism, Protein Serine-Threonine Kinases metabolism, Unfolded Protein Response drug effects, eIF-2 Kinase metabolism
- Abstract
The inability of cells to properly fold, modify and assemble secretory and transmembrane proteins leads to accumulation of misfolded proteins in the endoplasmic reticulum (ER). Under these conditions of 'ER stress', cell survival depends on homeostatic benefits from an intracellular signaling pathway called the unfolded protein response (UPR). When activated, the UPR induces transcriptional and translational programs that restore ER homeostasis. However, under high-level or chronic ER stress, these adaptive changes ultimately become overshadowed by alternative 'terminal UPR' signals that actively commit cells to degeneration, culminating in programmed cell death. Chronic ER stress and maladaptive UPR signaling are implicated in the etiology and pathogenesis of myriad human diseases. Naturally, this has generated widespread interest in targeting key nodal components of the UPR as therapeutic strategies. Here we summarize the state of this field with emphasis placed on two of the master UPR regulators, PERK and IRE1, which are both capable of being drugged with small molecules.
- Published
- 2014
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- View/download PDF
38. Allosteric inhibition of the IRE1α RNase preserves cell viability and function during endoplasmic reticulum stress.
- Author
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Ghosh R, Wang L, Wang ES, Perera BG, Igbaria A, Morita S, Prado K, Thamsen M, Caswell D, Macias H, Weiberth KF, Gliedt MJ, Alavi MV, Hari SB, Mitra AK, Bhhatarai B, Schürer SC, Snapp EL, Gould DB, German MS, Backes BJ, Maly DJ, Oakes SA, and Papa FR
- Subjects
- Allosteric Regulation, Animals, Apoptosis drug effects, Cell Line, Endoribonucleases chemistry, Endoribonucleases metabolism, Enzyme Activation drug effects, Humans, Islets of Langerhans metabolism, Male, Mice, Protein Serine-Threonine Kinases chemistry, Protein Serine-Threonine Kinases metabolism, Rats, Retina metabolism, Ribonucleases antagonists & inhibitors, Endoplasmic Reticulum Stress, Endoribonucleases antagonists & inhibitors, Protein Kinase Inhibitors pharmacology, Protein Serine-Threonine Kinases antagonists & inhibitors
- Abstract
Depending on endoplasmic reticulum (ER) stress levels, the ER transmembrane multidomain protein IRE1α promotes either adaptation or apoptosis. Unfolded ER proteins cause IRE1α lumenal domain homo-oligomerization, inducing trans autophosphorylation that further drives homo-oligomerization of its cytosolic kinase/endoribonuclease (RNase) domains to activate mRNA splicing of adaptive XBP1 transcription factor. However, under high/chronic ER stress, IRE1α surpasses an oligomerization threshold that expands RNase substrate repertoire to many ER-localized mRNAs, leading to apoptosis. To modulate these effects, we developed ATP-competitive IRE1α Kinase-Inhibiting RNase Attenuators-KIRAs-that allosterically inhibit IRE1α's RNase by breaking oligomers. One optimized KIRA, KIRA6, inhibits IRE1α in vivo and promotes cell survival under ER stress. Intravitreally, KIRA6 preserves photoreceptor functional viability in rat models of ER stress-induced retinal degeneration. Systemically, KIRA6 preserves pancreatic β cells, increases insulin, and reduces hyperglycemia in Akita diabetic mice. Thus, IRE1α powerfully controls cell fate but can itself be controlled with small molecules to reduce cell degeneration., (Copyright © 2014 Elsevier Inc. All rights reserved.)
- Published
- 2014
- Full Text
- View/download PDF
39. Establishment of a system for monitoring endoplasmic reticulum redox state in mammalian cells.
- Author
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Kanekura K, Ishigaki S, Merksamer PI, Papa FR, and Urano F
- Subjects
- Animals, Cell Line, Diabetes Mellitus metabolism, Endoplasmic Reticulum Stress, Green Fluorescent Proteins metabolism, HEK293 Cells, Homeostasis, Humans, Mice, Nerve Degeneration metabolism, Oxidation-Reduction, Protein Folding, Rats, Recombinant Proteins metabolism, Wolfram Syndrome metabolism, Computer Systems, Endoplasmic Reticulum metabolism
- Abstract
The endoplasmic reticulum (ER) performs a critical role in the oxidative folding of nascent proteins, such that perturbations to ER homeostasis may lead to protein misfolding and subsequent pathological processes. Among the mechanisms for maintaining ER homeostasis is a redox regulation, which is a critical determinant of the fate of ER-stressed cells. Here, we report the establishment of a system for monitoring the ER redox state in mammalian cells. The new ER redox-sensing system was developed based on the previously described monitoring system in yeast. Our system could successfully monitor the dynamic ER redox state in mammalian cells. Using this system, we find that manipulation of ER oxidases changes the ER redox state. The mammalian ER redox-sensing system could be used to study the mechanisms of ER redox regulation and provide a foundation for an approach to develop novel therapeutic modalities for human diseases related to dysregulated ER homeostasis including diabetes, neurodegeneration, and Wolfram syndrome.
- Published
- 2013
- Full Text
- View/download PDF
40. X-box binding protein 1 (XBP1s) is a critical determinant of Pseudomonas aeruginosa homoserine lactone-mediated apoptosis.
- Author
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Valentine CD, Anderson MO, Papa FR, and Haggie PM
- Subjects
- 4-Butyrolactone genetics, 4-Butyrolactone metabolism, Animals, Caspases genetics, Caspases metabolism, Cytotoxins genetics, DNA-Binding Proteins genetics, Enzyme Activation genetics, Eukaryotic Initiation Factor-2 genetics, Eukaryotic Initiation Factor-2 metabolism, MAP Kinase Signaling System genetics, Mice, Mice, Knockout, Pseudomonas aeruginosa genetics, Pseudomonas aeruginosa pathogenicity, Regulatory Factor X Transcription Factors, Transcription Factors genetics, X-Box Binding Protein 1, p38 Mitogen-Activated Protein Kinases genetics, p38 Mitogen-Activated Protein Kinases metabolism, 4-Butyrolactone analogs & derivatives, Apoptosis, Cytotoxins metabolism, DNA-Binding Proteins metabolism, Endoplasmic Reticulum Stress, Pseudomonas aeruginosa metabolism, Transcription Factors metabolism
- Abstract
Pseudomonas aeruginosa infections are associated with high mortality rates and occur in diverse conditions including pneumonias, cystic fibrosis and neutropenia. Quorum sensing, mediated by small molecules including N-(3-oxo-dodecanoyl) homoserine lactone (C12), regulates P. aeruginosa growth and virulence. In addition, host cell recognition of C12 initiates multiple signalling responses including cell death. To gain insight into mechanisms of C12-mediated cytotoxicity, we studied the role of endoplasmic reticulum stress in host cell responses to C12. Dramatic protection against C12-mediated cell death was observed in cells that do not produce the X-box binding protein 1 transcription factor (XBP1s). The leucine zipper and transcriptional activation motifs of XBP1s were sufficient to restore C12-induced caspase activation in XBP1s-deficient cells, although this polypeptide was not transcriptionally active. The XBP1s polypeptide also regulated caspase activation in cells stimulated with N-(3-oxo-tetradecanoyl) homoserine lactone (C14), produced by Yersinia enterolitica and Burkholderia pseudomallei, and enhanced homoserine lactone-mediated caspase activation in the presence of endogenous XBP1s. In C12-tolerant cells, responses to C12 including phosphorylation of p38 MAPK and eukaryotic initiation factor 2α were conserved, suggesting that C12 cytotoxicity is not heavily dependent on these pathways. In summary, this study reveals a novel and unconventional role for XBP1s in regulating host cell cytotoxic responses to bacterial acyl homoserine lactones.
- Published
- 2013
- Full Text
- View/download PDF
41. Divergent allosteric control of the IRE1α endoribonuclease using kinase inhibitors.
- Author
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Wang L, Perera BG, Hari SB, Bhhatarai B, Backes BJ, Seeliger MA, Schürer SC, Oakes SA, Papa FR, and Maly DJ
- Subjects
- Adaptor Proteins, Signal Transducing, Catalysis, Cells, Cultured, Cross-Linking Reagents, DNA-Binding Proteins metabolism, Down-Regulation drug effects, Endoplasmic Reticulum Stress physiology, Humans, Intracellular Signaling Peptides and Proteins, Isoenzymes antagonists & inhibitors, Isoenzymes metabolism, Molecular Conformation, Mutation genetics, Mutation physiology, Phosphorylation, RNA Splicing drug effects, Regulatory Factor X Transcription Factors, Ribonucleases metabolism, Transcription Factors metabolism, Unfolded Protein Response drug effects, Up-Regulation drug effects, X-Box Binding Protein 1, Endoribonucleases antagonists & inhibitors, Protein Kinase Inhibitors pharmacology, Protein Serine-Threonine Kinases antagonists & inhibitors
- Abstract
Under endoplasmic reticulum stress, unfolded protein accumulation leads to activation of the endoplasmic reticulum transmembrane kinase/endoRNase (RNase) IRE1α. IRE1α oligomerizes, autophosphorylates and initiates splicing of XBP1 mRNA, thus triggering the unfolded protein response (UPR). Here we show that IRE1α's kinase-controlled RNase can be regulated in two distinct modes with kinase inhibitors: one class of ligands occupies IRE1α's kinase ATP-binding site to activate RNase-mediated XBP1 mRNA splicing even without upstream endoplasmic reticulum stress, whereas a second class can inhibit the RNase through the same ATP-binding site, even under endoplasmic reticulum stress. Thus, alternative kinase conformations stabilized by distinct classes of ATP-competitive inhibitors can cause allosteric switching of IRE1α's RNase--either on or off. As dysregulation of the UPR has been implicated in a variety of cell degenerative and neoplastic disorders, small-molecule control over IRE1α should advance efforts to understand the UPR's role in pathophysiology and to develop drugs for endoplasmic reticulum stress-related diseases.
- Published
- 2012
- Full Text
- View/download PDF
42. IRE1α cleaves select microRNAs during ER stress to derepress translation of proapoptotic Caspase-2.
- Author
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Upton JP, Wang L, Han D, Wang ES, Huskey NE, Lim L, Truitt M, McManus MT, Ruggero D, Goga A, Papa FR, and Oakes SA
- Subjects
- 3' Untranslated Regions, Animals, Apoptosis, Brefeldin A pharmacology, Cell-Free System, Cells, Cultured, Down-Regulation, Endoplasmic Reticulum metabolism, Endoribonucleases chemistry, Endoribonucleases genetics, Enzyme Activation, HEK293 Cells, Humans, Mice, Mice, Knockout, Mutant Proteins, Protein Biosynthesis, Protein Serine-Threonine Kinases chemistry, Protein Serine-Threonine Kinases genetics, RNA Stability, RNA, Messenger genetics, RNA, Messenger metabolism, Up-Regulation, Caspase 2 genetics, Caspase 2 metabolism, Cysteine Endopeptidases genetics, Cysteine Endopeptidases metabolism, Endoplasmic Reticulum Stress, Endoribonucleases metabolism, MicroRNAs metabolism, Protein Serine-Threonine Kinases metabolism
- Abstract
The endoplasmic reticulum (ER) is the primary organelle for folding and maturation of secretory and transmembrane proteins. Inability to meet protein-folding demand leads to "ER stress," and activates IRE1α, an ER transmembrane kinase-endoribonuclease (RNase). IRE1α promotes adaptation through splicing Xbp1 mRNA or apoptosis through incompletely understood mechanisms. Here, we found that sustained IRE1α RNase activation caused rapid decay of select microRNAs (miRs -17, -34a, -96, and -125b) that normally repress translation of Caspase-2 mRNA, and thus sharply elevates protein levels of this initiator protease of the mitochondrial apoptotic pathway. In cell-free systems, recombinant IRE1α endonucleolytically cleaved microRNA precursors at sites distinct from DICER. Thus, IRE1α regulates translation of a proapoptotic protein through terminating microRNA biogenesis, and noncoding RNAs are part of the ER stress response.
- Published
- 2012
- Full Text
- View/download PDF
43. Endoplasmic reticulum stress, pancreatic β-cell degeneration, and diabetes.
- Author
-
Papa FR
- Subjects
- Apoptosis, Cell Death genetics, Diabetes Mellitus drug therapy, Diabetes Mellitus pathology, Endoplasmic Reticulum Stress physiology, Humans, Signal Transduction physiology, Unfolded Protein Response physiology, Diabetes Mellitus genetics, Endoplasmic Reticulum Stress genetics, Insulin-Secreting Cells physiology, Mutation genetics, Unfolded Protein Response genetics
- Abstract
Overwhelming of protein folding in the endoplasmic reticulum (ER)--referred to as "ER stress"--activates a set of intracellular signaling pathways termed the unfolded protein response (UPR). Beneficial outputs of the UPR promote adaptation in cells experiencing manageably low levels of ER stress. However, if ER stress reaches critically high levels, the UPR uses destructive outputs to trigger programmed cell death. Genetic mutations in various UPR components cause inherited syndromes of diabetes mellitus in both rodents and humans, implicating the UPR in the proper functioning and survival of pancreatic islet β cells. Markers of chronically elevated ER stress, terminal UPR signaling, and apoptosis are evident in β cells in these rare disorders; these markers are similarly present in islets of human patients with common forms of diabetes. These findings promise to enhance our molecular understanding of human diabetes significantly and may lead to new and effective therapies.
- Published
- 2012
- Full Text
- View/download PDF
44. IRE1α induces thioredoxin-interacting protein to activate the NLRP3 inflammasome and promote programmed cell death under irremediable ER stress.
- Author
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Lerner AG, Upton JP, Praveen PV, Ghosh R, Nakagawa Y, Igbaria A, Shen S, Nguyen V, Backes BJ, Heiman M, Heintz N, Greengard P, Hui S, Tang Q, Trusina A, Oakes SA, and Papa FR
- Subjects
- Animals, Blotting, Western, Cell Line, DNA Primers genetics, Flow Cytometry, Humans, Interleukin-1beta metabolism, Mice, Mice, Inbred C57BL, NLR Family, Pyrin Domain-Containing 3 Protein, Real-Time Polymerase Chain Reaction, Apoptosis physiology, Carrier Proteins metabolism, Endoplasmic Reticulum Stress physiology, Endoribonucleases metabolism, Inflammasomes metabolism, Protein Serine-Threonine Kinases metabolism, Thioredoxins metabolism, Unfolded Protein Response physiology
- Abstract
When unfolded proteins accumulate to irremediably high levels within the endoplasmic reticulum (ER), intracellular signaling pathways called the unfolded protein response (UPR) become hyperactivated to cause programmed cell death. We discovered that thioredoxin-interacting protein (TXNIP) is a critical node in this "terminal UPR." TXNIP becomes rapidly induced by IRE1α, an ER bifunctional kinase/endoribonuclease (RNase). Hyperactivated IRE1α increases TXNIP mRNA stability by reducing levels of a TXNIP destabilizing microRNA, miR-17. In turn, elevated TXNIP protein activates the NLRP3 inflammasome, causing procaspase-1 cleavage and interleukin 1β (IL-1β) secretion. Txnip gene deletion reduces pancreatic β cell death during ER stress and suppresses diabetes caused by proinsulin misfolding in the Akita mouse. Finally, small molecule IRE1α RNase inhibitors suppress TXNIP production to block IL-1β secretion. In summary, the IRE1α-TXNIP pathway is used in the terminal UPR to promote sterile inflammation and programmed cell death and may be targeted to develop effective treatments for cell degenerative diseases., (Copyright © 2012 Elsevier Inc. All rights reserved.)
- Published
- 2012
- Full Text
- View/download PDF
45. IRE1-dependent activation of AMPK in response to nitric oxide.
- Author
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Meares GP, Hughes KJ, Naatz A, Papa FR, Urano F, Hansen PA, Benveniste EN, and Corbett JA
- Subjects
- AMP-Activated Protein Kinase Kinases, AMP-Activated Protein Kinases antagonists & inhibitors, AMP-Activated Protein Kinases genetics, Animals, Calcium-Calmodulin-Dependent Protein Kinase Kinase metabolism, Cell Line, Endoplasmic Reticulum Stress, Endoribonucleases deficiency, Endoribonucleases genetics, Enzyme Activation drug effects, Gene Knockdown Techniques, Insulin-Secreting Cells drug effects, Insulin-Secreting Cells metabolism, MAP Kinase Kinase Kinases metabolism, Mechanistic Target of Rapamycin Complex 1, Mice, Models, Biological, Multiprotein Complexes, Nitric Oxide pharmacology, Protein Serine-Threonine Kinases deficiency, Protein Serine-Threonine Kinases genetics, Proteins antagonists & inhibitors, RNA, Small Interfering genetics, Rats, Signal Transduction, TOR Serine-Threonine Kinases, AMP-Activated Protein Kinases metabolism, Endoribonucleases metabolism, Membrane Proteins metabolism, Protein Serine-Threonine Kinases metabolism
- Abstract
While there can be detrimental consequences of nitric oxide production at pathological concentrations, eukaryotic cells have evolved protective mechanisms to defend themselves against this damage. The unfolded-protein response (UPR), activated by misfolded proteins and oxidative stress, is one adaptive mechanism that is employed to protect cells from stress. Nitric oxide is a potent activator of AMP-activated protein kinase (AMPK), and AMPK participates in the cellular defense against nitric oxide-mediated damage in pancreatic β-cells. In this study, the mechanism of AMPK activation by nitric oxide was explored. The known AMPK kinases LKB1, CaMKK, and TAK1 are not required for the activation of AMPK by nitric oxide. Instead, this activation is dependent on the endoplasmic reticulum (ER) stress-activated protein IRE1. Nitric oxide-induced AMPK phosphorylation and subsequent signaling to AMPK substrates, including Raptor, acetyl coenzyme A carboxylase, and PGC-1α, is attenuated in IRE1α-deficient cells. The endoribonuclease activity of IRE1 appears to be required for AMPK activation in response to nitric oxide. In addition to nitric oxide, stimulation of IRE1 endoribonuclease activity with the flavonol quercetin leads to IRE1-dependent AMPK activation. These findings indicate that the RNase activity of IRE1 participates in AMPK activation and subsequent signaling through multiple AMPK-dependent pathways in response to nitrosative stress.
- Published
- 2011
- Full Text
- View/download PDF
46. Signaling cell death from the endoplasmic reticulum stress response.
- Author
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Shore GC, Papa FR, and Oakes SA
- Subjects
- Animals, Cell Death, Humans, Protein Unfolding, Endoplasmic Reticulum metabolism, Signal Transduction, Stress, Physiological
- Abstract
Inability to meet protein folding demands within the endoplasmic reticulum (ER) activates the unfolded protein response (UPR), a signaling pathway with both adaptive and apoptotic outputs. While some secretory cell types have a remarkable ability to increase protein folding capacity, their upper limits can be reached when pathological conditions overwhelm the fidelity and/or output of the secretory pathway. Irremediable 'ER stress' induces apoptosis and contributes to cell loss in several common human diseases, including type 2 diabetes and neurodegeneration. Researchers have begun to elucidate the molecular switches that determine when ER stress is too great to repair and the signals that are then sent from the UPR to execute the cell., (Copyright © 2010 Elsevier Ltd. All rights reserved.)
- Published
- 2011
- Full Text
- View/download PDF
47. The UPR and cell fate at a glance.
- Author
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Merksamer PI and Papa FR
- Subjects
- Animals, Humans, Peptide Hydrolases metabolism, Signal Transduction, Apoptosis, Endoplasmic Reticulum, Protein Folding, Unfolded Protein Response
- Published
- 2010
- Full Text
- View/download PDF
48. Spontaneous development of endoplasmic reticulum stress that can lead to diabetes mellitus is associated with higher calcium-independent phospholipase A2 expression: a role for regulation by SREBP-1.
- Author
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Lei X, Zhang S, Barbour SE, Bohrer A, Ford EL, Koizumi A, Papa FR, and Ramanadham S
- Subjects
- Animals, Apoptosis, Binding Sites, Humans, Insulin-Secreting Cells, Mice, Mice, Transgenic, Protein Binding, Stress, Physiological, Diabetes Mellitus etiology, Endoplasmic Reticulum pathology, Phospholipases A2, Calcium-Independent genetics, Sterol Regulatory Element Binding Protein 1 physiology, Transcription, Genetic
- Abstract
Our recent studies indicate that endoplasmic reticulum (ER) stress causes INS-1 cell apoptosis by a Ca(2+)-independent phospholipase A(2) (iPLA(2)beta)-mediated mechanism that promotes ceramide generation via sphingomyelin hydrolysis and subsequent activation of the intrinsic pathway. To elucidate the association between iPLA(2)beta and ER stress, we compared beta-cell lines generated from wild type (WT) and Akita mice. The Akita mouse is a spontaneous model of ER stress that develops hyperglycemia/diabetes due to ER stress-induced beta-cell apoptosis. Consistent with a predisposition to developing ER stress, basal phosphorylated PERK and activated caspase-3 are higher in the Akita cells than WT cells. Interestingly, basal iPLA(2)beta, mature SREBP-1 (mSREBP-1), phosphorylated Akt, and neutral sphingomyelinase (NSMase) are higher, relative abundances of sphingomyelins are lower, and mitochondrial membrane potential (DeltaPsi) is compromised in Akita cells, in comparison with WT cells. Exposure to thapsigargin accelerates DeltaPsi loss and apoptosis of Akita cells and is associated with increases in iPLA(2)beta, mSREBP-1, and NSMase in both WT and Akita cells. Transfection of Akita cells with iPLA(2)beta small interfering RNA, however, suppresses NSMase message, DeltaPsi loss, and apoptosis. The iPLA(2)beta gene contains a sterol-regulatory element, and transfection with a dominant negative SREBP-1 reduces basal mSREBP-1 and iPLA(2)beta in the Akita cells and suppresses increases in mSREBP-1 and iPLA(2)beta due to thapsigargin. These findings suggest that ER stress leads to generation of mSREBP-1, which can bind to the sterol-regulatory element in the iPLA(2)beta gene to promote its transcription. Consistent with this, SREBP-1, iPLA(2)beta, and NSMase messages in Akita mouse islets are higher than in WT islets.
- Published
- 2010
- Full Text
- View/download PDF
49. IRE1alpha kinase activation modes control alternate endoribonuclease outputs to determine divergent cell fates.
- Author
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Han D, Lerner AG, Vande Walle L, Upton JP, Xu W, Hagen A, Backes BJ, Oakes SA, and Papa FR
- Subjects
- Animals, Cell Line, Cell Line, Tumor, Cells metabolism, Endoplasmic Reticulum metabolism, Insulin genetics, Multienzyme Complexes, Protein Folding, Protein Serine-Threonine Kinases, RNA Stability, Rats, Ribonucleases, Endoribonucleases metabolism
- Abstract
During endoplasmic reticulum (ER) stress, homeostatic signaling through the unfolded protein response (UPR) augments ER protein-folding capacity. If homeostasis is not restored, the UPR triggers apoptosis. We found that the ER transmembrane kinase/endoribonuclease (RNase) IRE1alpha is a key component of this apoptotic switch. ER stress induces IRE1alpha kinase autophosphorylation, activating the RNase to splice XBP1 mRNA and produce the homeostatic transcription factor XBP1s. Under ER stress--or forced autophosphorylation--IRE1alpha's RNase also causes endonucleolytic decay of many ER-localized mRNAs, including those encoding chaperones, as early events culminating in apoptosis. Using chemical genetics, we show that kinase inhibitors bypass autophosphorylation to activate the RNase by an alternate mode that enforces XBP1 splicing and averts mRNA decay and apoptosis. Alternate RNase activation by kinase-inhibited IRE1alpha can be reconstituted in vitro. We propose that divergent cell fates during ER stress hinge on a balance between IRE1alpha RNase outputs that can be tilted with kinase inhibitors to favor survival.
- Published
- 2009
- Full Text
- View/download PDF
50. Rationalizing translation attenuation in the network architecture of the unfolded protein response.
- Author
-
Trusina A, Papa FR, and Tang C
- Subjects
- Animals, Insulin-Secreting Cells metabolism, Molecular Chaperones biosynthesis, Protein Transport, Proteins metabolism, Species Specificity, Yeasts metabolism, eIF-2 Kinase, Endoplasmic Reticulum physiology, Gene Expression Regulation, Models, Chemical, Protein Biosynthesis
- Abstract
Increased levels of unfolded proteins in the endoplasmic reticulum (ER) of all eukaryotes trigger the unfolded protein response (UPR). Lower eukaryotes solely use an ancient UPR mechanism, whereby they up-regulate ER-resident chaperones and other enzymatic activities to augment protein folding and enhance degradation of misfolded proteins. Metazoans have evolved an additional mechanism through which they attenuate translation of secretory pathway proteins by activating the ER protein kinase PERK. In mammalian professional secretory cells such as insulin-producing pancreatic beta-cells, PERK is highly abundant and crucial for proper functioning of the secretory pathway. Through a modeling approach, we propose explanations for why a translation attenuation (TA) mechanism may be critical for beta-cells, but is less important in nonsecretory cells and unnecessary in lower eukaryotes such as yeast. We compared the performance of a model UPR, both with and without a TA mechanism, by monitoring 2 variables: (i) the maximal increase in ER unfolded proteins during a response, and (ii) the accumulation of chaperones between 2 consecutive pulses of stress. We found that a TA mechanism is important for minimizing these 2 variables when the ER is repeatedly subjected to transient unfolded protein stresses and when it sustains a large flux of secretory pathway proteins which are both conditions encountered physiologically by pancreatic beta-cells. Low expression of PERK in nonsecretory cells, and its absence in yeast, can be rationalized by lower trafficking of secretory proteins through their ERs.
- Published
- 2008
- Full Text
- View/download PDF
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