1
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Dabsan S, Twito G, Biadsy S, Igbaria A. Less is better: various means to reduce protein load in the endoplasmic reticulum. FEBS J 2024. [PMID: 38865586 DOI: 10.1111/febs.17201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 04/08/2024] [Accepted: 06/05/2024] [Indexed: 06/14/2024]
Abstract
The endoplasmic reticulum (ER) is an important organelle that controls the intracellular and extracellular environments. The ER is responsible for folding almost one-third of the total protein population in the eukaryotic cell. Disruption of ER-protein folding is associated with numerous human diseases, including metabolic disorders, neurodegenerative diseases, and cancer. During ER perturbations, the cells deploy various mechanisms to increase the ER-folding capacity and reduce ER-protein load by minimizing the number of substrates entering the ER to regain homeostasis. These mechanisms include signaling pathways, degradation mechanisms, and other processes that mediate the reflux of ER content to the cytosol. In this review, we will discuss the recent discoveries of five different ER quality control mechanisms, including the unfolded protein response (UPR), ER-associated-degradation (ERAD), pre-emptive quality control, ER-phagy and ER to cytosol signaling (ERCYS). We will discuss the roles of these processes in decreasing ER-protein load and inter-mechanism crosstalk.
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Affiliation(s)
- Salam Dabsan
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Gal Twito
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Suma Biadsy
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Aeid Igbaria
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
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2
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McNamee SM, Chan NP, Akula M, Avola MO, Whalen M, Nystuen K, Singh P, Upadhyay AK, DeAngelis MM, Haider NB. Preclinical dose response study shows NR2E3 can attenuate retinal degeneration in the retinitis pigmentosa mouse model Rho P23H+/. Gene Ther 2024; 31:255-262. [PMID: 38273095 PMCID: PMC11090815 DOI: 10.1038/s41434-024-00440-6] [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: 09/14/2023] [Revised: 12/26/2023] [Accepted: 01/03/2024] [Indexed: 01/27/2024]
Abstract
Retinitis pigmentosa (RP) is a heterogeneous disease and the main cause of vision loss within the group of inherited retinal diseases (IRDs). IRDs are a group of rare disorders caused by mutations in one or more of over 280 genes which ultimately result in blindness. Modifier genes play a key role in modulating disease phenotypes, and mutations in them can affect disease outcomes, rate of progression, and severity. Our previous studies have demonstrated that the nuclear hormone receptor 2 family e, member 3 (Nr2e3) gene reduced disease progression and loss of photoreceptor cell layers in RhoP23H-/- mice. This follow up, pharmacology study evaluates a longitudinal NR2E3 dose response in the clinically relevant heterozygous RhoP23H mouse. Reduced retinal degeneration and improved retinal morphology was observed 6 months following treatment evaluating three different NR2E3 doses. Histological and immunohistochemical analysis revealed regions of photoreceptor rescue in the treated retinas of RhoP23H+/- mice. Functional assessment by electroretinogram (ERG) showed attenuated photoreceptor degeneration with all doses. This study demonstrates the effectiveness of different doses of NR2E3 at reducing retinal degeneration and informs dose selection for clinical trials of RhoP23H-associated RP.
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Affiliation(s)
- Shannon M McNamee
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Natalie P Chan
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Monica Akula
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Marielle O Avola
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Maiya Whalen
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Kaden Nystuen
- University of Massachusetts Amherst, Amherst, MA, USA
| | | | | | - Margaret M DeAngelis
- Department of Ophthalmology, Jacobs School of Medicine & Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Neena B Haider
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
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3
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Li Y, Liu D, Wang H, Zhang X, Lu B, Li S. The IRE1/Xbp1 axis restores ER and tissue homeostasis perturbed by excess Notch in Drosophila. Dev Biol 2024; 507:11-19. [PMID: 38142805 DOI: 10.1016/j.ydbio.2023.12.007] [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: 08/28/2023] [Revised: 12/15/2023] [Accepted: 12/17/2023] [Indexed: 12/26/2023]
Abstract
Notch signaling controls numerous key cellular processes including cell fate determination and cell proliferation. Its malfunction has been linked to many developmental abnormalities and human disorders. Overactivation of Notch signaling is shown to be oncogenic. Retention of excess Notch protein in the endoplasmic reticulum (ER) can lead to altered Notch signaling and cell fate, but the mechanism is not well understood. In this study, we show that V5-tagged or untagged exogenous Notch is retained in the ER when overexpressed in fly tissues. Furthermore, we show that Notch retention in the ER leads to robust ER enlargement and elicits a rough eye phenotype. Gain-of-function of unfolded protein response (UPR) factors IRE1 or spliced Xbp1 (Xbp1-s) alleviates Notch accumulation in the ER, restores ER morphology and ameliorates the rough eye phenotype. Our results uncover a pivotal role of the IRE1/Xbp1 axis in regulating the detrimental effect of ER-localized excess Notch protein during development and tissue homeostasis.
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Affiliation(s)
- Yu Li
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Dongyue Liu
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Haochuan Wang
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Xuejing Zhang
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China
| | - Bingwei Lu
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Shuangxi Li
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, China.
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4
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Zhao N, Li N, Wang T. PERK prevents rhodopsin degradation during retinitis pigmentosa by inhibiting IRE1-induced autophagy. J Cell Biol 2023; 222:e202208147. [PMID: 37022709 PMCID: PMC10082367 DOI: 10.1083/jcb.202208147] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 01/04/2023] [Accepted: 02/14/2023] [Indexed: 04/07/2023] Open
Abstract
Chronic endoplasmic reticulum (ER) stress is the underlying cause of many degenerative diseases, including autosomal dominant retinitis pigmentosa (adRP). In adRP, mutant rhodopsins accumulate and cause ER stress. This destabilizes wild-type rhodopsin and triggers photoreceptor cell degeneration. To reveal the mechanisms by which these mutant rhodopsins exert their dominant-negative effects, we established an in vivo fluorescence reporter system to monitor mutant and wild-type rhodopsin in Drosophila. By performing a genome-wide genetic screen, we found that PERK signaling plays a key role in maintaining rhodopsin homeostasis by attenuating IRE1 activities. Degradation of wild-type rhodopsin is mediated by selective autophagy of ER, which is induced by uncontrolled IRE1/XBP1 signaling and insufficient proteasome activities. Moreover, upregulation of PERK signaling prevents autophagy and suppresses retinal degeneration in the adRP model. These findings establish a pathological role for autophagy in this neurodegenerative condition and indicate that promoting PERK activity could be used to treat ER stress-related neuropathies, including adRP.
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Affiliation(s)
- Ning Zhao
- Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Ning Li
- College of Biological Sciences, China Agricultural University, Beijing, China
| | - Tao Wang
- Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
- College of Biological Sciences, China Agricultural University, Beijing, China
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China
- National Institute of Biological Sciences, Beijing, China
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5
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Chen APF, Chea L, Lee EJ, Lin JH. Lysine Ubiquitylation Drives Rhodopsin Protein Turnover. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:493-498. [PMID: 37440077 DOI: 10.1007/978-3-031-27681-1_72] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Rhodopsin is a G-protein-coupled receptor that is specifically and abundantly expressed in rod photoreceptors. Over 150 rhodopsin mutations cause autosomal dominant retinitis pigmentosa (adRP). The most common mutation in the United States is the conversion of proline to histidine at position 23 (P23H) in the N-terminal domain of rhodopsin. We previously found that P23H rhodopsin was misfolded, ubiquitinylated, and rapidly degraded. Here, we investigated the role of lysine residues on P23H rhodopsin ubiquitinylation and turnover. We transfected HEK293 cells with a P23H human rhodopsin construct where all 11 lysine residues were mutated to arginine (K-null P23H). We found that the K-null P23H rhodopsin was significantly less ubiquitylated than intact P23H rhodopsin. We found that K-null P23H protein turnover was significantly slower compared to P23H rhodopsin through cycloheximide chase analysis. Finally, we also generated a wild-type rhodopsin construct where all lysines were converted to arginine and found significantly reduced ubiquitylation. Our findings identify ubiquitinylation of lysine residues as an important posttranslational modification involved in P23H rhodopsin protein degradation.
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Affiliation(s)
- Allen P F Chen
- Medical Scientist Training Program, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, USA
| | - Leon Chea
- Department of Ophthalmology, Palo Alto, CA, USA
- Department of Pathology, Stanford University, Palo Alto, CA, USA
- VA Palo Alto Healthcare System, Palo Alto, CA, USA
| | - Eun-Jin Lee
- Department of Ophthalmology, Palo Alto, CA, USA
- Department of Pathology, Stanford University, Palo Alto, CA, USA
- VA Palo Alto Healthcare System, Palo Alto, CA, USA
- USC ROSKI Eye Institute and Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Jonathan H Lin
- Department of Ophthalmology, Palo Alto, CA, USA.
- Department of Pathology, Stanford University, Palo Alto, CA, USA.
- VA Palo Alto Healthcare System, Palo Alto, CA, USA.
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6
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Network biology analysis of P23H rhodopsin interactome identifies protein and mRNA quality control mechanisms. Sci Rep 2022; 12:17405. [PMID: 36258031 PMCID: PMC9579138 DOI: 10.1038/s41598-022-22316-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/12/2022] [Indexed: 02/05/2023] Open
Abstract
Rhodopsin is essential for phototransduction, and many rhodopsin mutations cause heritable retinal degenerations. The P23H rhodopsin variant generates a misfolded rhodopsin protein that photoreceptors quickly target for degradation by mechanisms that are incompletely understood. To gain insight into how P23H rhodopsin is removed from rods, we used mass spectrometry to identify protein interaction partners of P23H rhodopsin immunopurified from RhoP23H/P23H mice and compared them with protein interaction partners of wild-type rhodopsin from Rho+/+ mice. We identified 286 proteins associated with P23H rhodopsin and 276 proteins associated with wild-type rhodopsin. 113 proteins were shared between wild-type and mutant rhodopsin protein interactomes. In the P23H rhodopsin protein interactome, we saw loss of phototransduction, retinal cycle, and rhodopsin protein trafficking proteins but gain of ubiquitin-related proteins when compared with the wild-type rhodopsin protein interactome. In the P23H rhodopsin protein interactome, we saw enrichment of gene ontology terms related to ER-associated protein degradation, ER stress, and translation. Protein-protein interaction network analysis revealed that translational and ribosomal quality control proteins were significant regulators in the P23H rhodopsin protein interactome. The protein partners identified in our study may provide new insights into how photoreceptors recognize and clear mutant rhodopsin, offering possible novel targets involved in retinal degeneration pathogenesis.
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7
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Kennedy A, Ren HY, Madden VJ, Cyr DM. Lysosome docking to WIPI1 rings and ER-connected phagophores occurs during DNAJB12- and GABARAP-dependent selective autophagy of misfolded P23H-rhodopsin. Mol Biol Cell 2022; 33:ar84. [PMID: 35704470 PMCID: PMC9582645 DOI: 10.1091/mbc.e21-10-0505] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We report on how the endoplasmic reticulum (ER)-associated-autophagy pathway (ERAA) delivers P23H-rhodopsin (P23H-R) to the lysosome. P23H-R accumulates in an ERAD-resistant conformation that is stabilized in a detergent-soluble state by DNAJB12 and Hsp70. P23H-R, DNAJB12, and FIP200 colocalize in discrete foci that punctuate the rim of omegasome rings coated by WIPI1. Loss of DNAJB12 function prevents the association of P23H-R containing ER tubules with omegasomes. P23H-R tubules thread through the wall of WIPI1 rings into their central cavity. Transfer of P23H-R from ER-connected phagophores to lysosomes requires GABARAP and is associated with the transient docking of lysosomes to WIPI1 rings. After departure from WIPI1 rings, new patches of P23H-R are seen in the membranes of lysosomes. The absence of GABARAP prevents transfer of P23H-R from phagophores to lysosomes without interfering with docking. These data identify lysosome docking to omegasomes as an important step in the DNAJB12- and GABARAP-dependent autophagic disposal of dominantly toxic P23H-R.
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Affiliation(s)
- Andrew Kennedy
- Department of Cell Biology and Physiology, School of Medicine, and
| | - Hong Yu Ren
- Department of Cell Biology and Physiology, School of Medicine, and
| | - Victoria J. Madden
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Douglas M. Cyr
- Department of Cell Biology and Physiology, School of Medicine, and,*Address correspondence to: Douglas M. Cyr ()
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8
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Lee EJ, Chan P, Chea L, Kim K, Kaufman RJ, Lin JH. ATF6 is required for efficient rhodopsin clearance and retinal homeostasis in the P23H rho retinitis pigmentosa mouse model. Sci Rep 2021; 11:16356. [PMID: 34381136 PMCID: PMC8357971 DOI: 10.1038/s41598-021-95895-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 07/26/2021] [Indexed: 12/21/2022] Open
Abstract
Retinitis Pigmentosa (RP) is a blinding disease that arises from loss of rods and subsequently cones. The P23H rhodopsin knock-in (P23H-KI) mouse develops retinal degeneration that mirrors RP phenotype in patients carrying the orthologous variant. Previously, we found that the P23H rhodopsin protein was degraded in P23H-KI retinas, and the Unfolded Protein Response (UPR) promoted P23H rhodopsin degradation in heterologous cells in vitro. Here, we investigated the role of a UPR regulator gene, activating transcription factor 6 (Atf6), in rhodopsin protein homeostasis in heterozygous P23H rhodopsin (Rho+/P23H) mice. Significantly increased rhodopsin protein levels were found in Atf6-/-Rho+/P23H retinas compared to Atf6+/-Rho+/P23H retinas at early ages (~ P12), while rhodopsin mRNA levels were not different. The IRE1 pathway of the UPR was hyper-activated in young Atf6-/-Rho+/P23H retinas, and photoreceptor layer thickness was unchanged at this early age in Rho+/P23H mice lacking Atf6. By contrast, older Atf6-/-Rho+/P23H mice developed significantly increased retinal degeneration in comparison to Atf6+/-Rho+/P23H mice in all retinal layers, accompanied by reduced rhodopsin protein levels. Our findings demonstrate that Atf6 is required for efficient clearance of rhodopsin protein in rod photoreceptors expressing P23H rhodopsin, and that loss of Atf6 ultimately accelerates retinal degeneration in P23H-KI mice.
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Affiliation(s)
- Eun-Jin Lee
- Department of Ophthalmology, Stanford University, Palo Alto, CA, USA.,Department of Pathology, Stanford University, Palo Alto, CA, USA.,VA Palo Alto Healthcare System, Palo Alto, CA, USA.,USC ROSKI Eye Institute and Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Priscilla Chan
- Department of Neurology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Leon Chea
- Department of Ophthalmology, Stanford University, Palo Alto, CA, USA.,Department of Pathology, Stanford University, Palo Alto, CA, USA.,VA Palo Alto Healthcare System, Palo Alto, CA, USA
| | - Kyle Kim
- Department of Ophthalmology, Stanford University, Palo Alto, CA, USA.,Department of Pathology, Stanford University, Palo Alto, CA, USA.,VA Palo Alto Healthcare System, Palo Alto, CA, USA
| | - Randal J Kaufman
- Degenerative Diseases Program, Sanford-Burnham-Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Jonathan H Lin
- Department of Ophthalmology, Stanford University, Palo Alto, CA, USA. .,Department of Pathology, Stanford University, Palo Alto, CA, USA. .,VA Palo Alto Healthcare System, Palo Alto, CA, USA. .,School of Medicine, Stanford University, 300 Pasteur Dr. L235, Palo Alto, CA, 94305, USA.
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9
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Kryvenko V, Wessendorf M, Tello K, Herold S, Morty RE, Seeger W, Vadász I. Hypercapnia-induces IRE1α-driven Endoplasmic Reticulum-associated Degradation of the Na,K-ATPase β-subunit. Am J Respir Cell Mol Biol 2021; 65:615-629. [PMID: 34192507 DOI: 10.1165/rcmb.2021-0114oc] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Acute respiratory distress syndrome (ARDS) is often associated with elevated levels of CO2 (hypercapnia) and impaired alveolar fluid clearance. Misfolding of the Na,K-ATPase (NKA), a key molecule involved in both alveolar epithelial barrier tightness and in resolution of alveolar edema, in the endoplasmic reticulum (ER) may decrease plasma membrane (PM) abundance of the transporter. Here, we investigated how hypercapnia affects the NKA β-subunit (NKA-β) in the ER. Exposing murine precision-cut lung slices (PCLS) and human alveolar epithelial A549 cells to elevated CO2 levels led to a rapid decrease of NKA-β abundance in the ER and at the cell surface. Knockdown of ER alpha-mannosidase I (MAN1B1) and ER degradation enhancing alpha-mannosidase like protein 1 by siRNA or treatment with the MAN1B1 inhibitor, kifunensine rescued loss of NKA-β in the ER, suggesting ER-associated degradation (ERAD) of the enzyme. Furthermore, hypercapnia activated the unfolded protein response (UPR) by promoting phosphorylation of inositol-requiring enzyme 1α (IRE1α) and treatment with a siRNA against IRE1α prevented the decrease of NKA-β in the ER. Of note, the hypercapnia-induced phosphorylation of IRE1α was triggered by a Ca2+-dependent mechanism. Additionally, inhibition of the inositol trisphosphate receptor decreased phosphorylation levels of IRE1α in PCLS and A549 cells, suggesting that Ca2+ efflux from the ER might be responsible for IRE1α activation and ERAD of NKA-β. In conclusion, here we provide evidence that hypercapnia attenuates maturation of the regulatory subunit of NKA by activating IRE1α and promoting ERAD, which may contribute to impaired alveolar epithelial integrity in patients with ARDS and hypercapnia.
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Affiliation(s)
- Vitalii Kryvenko
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany.,The Cardio-Pulmonary Institute, Giessen, Germany
| | - Miriam Wessendorf
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany
| | - Khodr Tello
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany.,The Cardio-Pulmonary Institute, Giessen, Germany
| | - Susanne Herold
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany.,The Cardio-Pulmonary Institute, Giessen, Germany
| | - Rory E Morty
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany.,The Cardio-Pulmonary Institute, Giessen, Germany.,Max-Planck-Institute for Heart and Lung Research, Department of Lung Development and Remodeling, Bad Nauheim, Germany
| | - Werner Seeger
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany.,The Cardio-Pulmonary Institute, Giessen, Germany.,Max-Planck-Institute for Heart and Lung Research, Department of Lung Development and Remodeling, Bad Nauheim, Germany.,Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany
| | - István Vadász
- Justus Liebig University, Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research, Department of Internal Medicine, Giessen, Germany.,The Cardio-Pulmonary Institute, Giessen, Germany;
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10
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Li S, Datta S, Brabbit E, Love Z, Woytowicz V, Flattery K, Capri J, Yao K, Wu S, Imboden M, Upadhyay A, Arumugham R, Thoreson WB, DeAngelis MM, Haider NB. Nr2e3 is a genetic modifier that rescues retinal degeneration and promotes homeostasis in multiple models of retinitis pigmentosa. Gene Ther 2021; 28:223-241. [PMID: 32123325 PMCID: PMC7483267 DOI: 10.1038/s41434-020-0134-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 02/05/2020] [Accepted: 02/18/2020] [Indexed: 12/21/2022]
Abstract
Recent advances in viral vector engineering, as well as an increased understanding of the cellular and molecular mechanism of retinal diseases, have led to the development of novel gene therapy approaches. Furthermore, ease of accessibility and ocular immune privilege makes the retina an ideal target for gene therapies. In this study, the nuclear hormone receptor gene Nr2e3 was evaluated for efficacy as broad-spectrum therapy to attenuate early to intermediate stages of retinal degeneration in five unique mouse models of retinitis pigmentosa (RP). RP is a group of heterogenic inherited retinal diseases associated with over 150 gene mutations, affecting over 1.5 million individuals worldwide. RP varies in age of onset, severity, and rate of progression. In addition, ~40% of RP patients cannot be genetically diagnosed, confounding the ability to develop personalized RP therapies. Remarkably, Nr2e3 administered therapy resulted in reduced retinal degeneration as observed by increase in photoreceptor cells, improved electroretinogram, and a dramatic molecular reset of key transcription factors and associated gene networks. These therapeutic effects improved retinal homeostasis in diseased tissue. Results of this study provide evidence that Nr2e3 can serve as a broad-spectrum therapy to treat multiple forms of RP.
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Affiliation(s)
- Sujun Li
- Department of Ophthalmology, Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Shyamtanu Datta
- Department of Ophthalmology, Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Emily Brabbit
- Department of Ophthalmology, Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Zoe Love
- Department of Ophthalmology, Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Victoria Woytowicz
- Department of Ophthalmology, Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Kyle Flattery
- Department of Ophthalmology, Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Jessica Capri
- Department of Ophthalmology, Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Katie Yao
- Department of Ophthalmology, Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Siqi Wu
- Department of Ophthalmology, Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | | | | | | | - Wallace B Thoreson
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center, Omaha, NE, USA
| | | | - Neena B Haider
- Department of Ophthalmology, Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.
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11
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Starting at the beginning: endoplasmic reticulum proteostasis and systemic amyloid disease. Biochem J 2020; 477:1721-1732. [PMID: 32412081 DOI: 10.1042/bcj20190312] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/21/2020] [Accepted: 04/22/2020] [Indexed: 12/20/2022]
Abstract
Systemic amyloid diseases are characterized by the deposition of an amyloidogenic protein as toxic oligomers and amyloid fibrils on tissues distal from the site of protein synthesis. Traditionally, these diseases have been viewed as disorders of peripheral target tissues where aggregates are deposited, and toxicity is observed. However, recent evidence highlights an important role for endoplasmic reticulum (ER) proteostasis pathways within tissues synthesizing and secreting amyloidogenic proteins, such as the liver, in the pathogenesis of these disorders. Here, we describe the pathologic implications of ER proteostasis and its regulation on the toxic extracellular aggregation of amyloidogenic proteins implicated in systemic amyloid disease pathogenesis. Furthermore, we discuss the therapeutic potential for targeting ER proteostasis to reduce the secretion and toxic aggregation of amyloidogenic proteins to mitigate peripheral amyloid-associated toxicity involved in the onset and progression of systemic amyloid diseases.
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12
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Xu J, Zhao H, Wang T. Suppression of retinal degeneration by two novel ERAD ubiquitin E3 ligases SORDD1/2 in Drosophila. PLoS Genet 2020; 16:e1009172. [PMID: 33137101 PMCID: PMC7660902 DOI: 10.1371/journal.pgen.1009172] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 11/12/2020] [Accepted: 10/05/2020] [Indexed: 12/13/2022] Open
Abstract
Mutations in the gene rhodopsin are one of the major causes of autosomal dominant retinitis pigmentosa (adRP). Mutant forms of Rhodopsin frequently accumulate in the endoplasmic reticulum (ER), cause ER stress, and trigger photoreceptor cell degeneration. Here, we performed a genome-wide screen to identify suppressors of retinal degeneration in a Drosophila model of adRP, carrying a point mutation in the major rhodopsin, Rh1 (Rh1G69D). We identified two novel E3 ubiquitin ligases SORDD1 and SORDD2 that effectively suppressed Rh1G69D-induced photoreceptor dysfunction and retinal degeneration. SORDD1/2 promoted the ubiquitination and degradation of Rh1G69D through VCP (valosin containing protein) and independent of processes reliant on the HRD1 (HMG-CoA reductase degradation protein 1)/HRD3 complex. We further demonstrate that SORDD1/2 and HRD1 function in parallel and in a redundant fashion to maintain rhodopsin homeostasis and integrity of photoreceptor cells. These findings identify a new ER-associated protein degradation (ERAD) pathway and suggest that facilitating SORDD1/2 function may be a therapeutic strategy to treat adRP. Misfolded rhodopsins accumulated in endoplasmic reticulum (ER) could disrupt the homeostasis of the ER and cause ER stress. Chronic ER stress would finally lead to photoreceptor cell death and retinal degeneration. To diminish the stress and sustain homeostasis cells develop alternative strategies to clear the misfolded rhodopsins. Previous studies have suggested that ubiquitin E3 ligase HRD1 is involved in the degradation of misfolded rhodopsins. In this study, we define novel ubiquitin E3 ligase SORDD1/2 based on a genetic screen and demonstrate that SORDD1/2 promotes the degradation of misfolded rhodopsins through ER-associated degradation (ERAD) pathway. Furthermore, we demonstrate that SORDD1/2 function independently of HRD1 in misfolded rhodopsins degradation. We also show SORDD1/2 and HRD1 play redundant roles in rhodopsin homeostasis. Finally, we demonstrate that SORDD1 works well in a Drosophila disease model. Our studies identify a novel ERAD pathway that acts in parallel to HRD1, and suggest that SORDD1 is a good candidate therapeutic target.
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Affiliation(s)
- Jaiwei Xu
- College of Biological Sciences, China Agricultural University, China
- National Institute of Biological Sciences, China
| | - Haifang Zhao
- National Institute of Biological Sciences, China
| | - Tao Wang
- National Institute of Biological Sciences, China
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, China
- * E-mail:
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13
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Brown M, Dainty S, Strudwick N, Mihai AD, Watson JN, Dendooven R, Paton AW, Paton JC, Schröder M. Endoplasmic reticulum stress causes insulin resistance by inhibiting delivery of newly synthesized insulin receptors to the cell surface. Mol Biol Cell 2020; 31:2597-2629. [PMID: 32877278 PMCID: PMC7851869 DOI: 10.1091/mbc.e18-01-0013] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 08/21/2020] [Accepted: 08/28/2020] [Indexed: 12/20/2022] Open
Abstract
Accumulation of unfolded proteins in the endoplasmic reticulum (ER) causes ER stress and activates a signaling network known as the unfolded protein response (UPR). Here we characterize how ER stress and the UPR inhibit insulin signaling. We find that ER stress inhibits insulin signaling by depleting the cell surface population of the insulin receptor. ER stress inhibits proteolytic maturation of insulin proreceptors by interfering with transport of newly synthesized insulin proreceptors from the ER to the plasma membrane. Activation of AKT, a major target of the insulin signaling pathway, by a cytosolic, membrane-bound chimera between the AP20187-inducible FV2E dimerization domain and the cytosolic protein tyrosine kinase domain of the insulin receptor was not affected by ER stress. Hence, signaling events in the UPR, such as activation of the JNK mitogen-activated protein (MAP) kinases or the pseudokinase TRB3 by the ER stress sensors IRE1α and PERK, do not contribute to inhibition of signal transduction in the insulin signaling pathway. Indeed, pharmacologic inhibition and genetic ablation of JNKs, as well as silencing of expression of TRB3, did not restore insulin sensitivity or rescue processing of newly synthesized insulin receptors in ER-stressed cells. [Media: see text].
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Affiliation(s)
- Max Brown
- Department of Biosciences, Durham University, Durham DH1 3LE, United Kingdom
- Biophysical Sciences Institute, Durham University, Durham DH1 3LE, United Kingdom
- North East England Stem Cell Institute (NESCI), Newcastle Upon Tyne NE1 4EP, United Kingdom
| | - Samantha Dainty
- Department of Biosciences, Durham University, Durham DH1 3LE, United Kingdom
- Biophysical Sciences Institute, Durham University, Durham DH1 3LE, United Kingdom
- North East England Stem Cell Institute (NESCI), Newcastle Upon Tyne NE1 4EP, United Kingdom
| | - Natalie Strudwick
- Department of Biosciences, Durham University, Durham DH1 3LE, United Kingdom
- Biophysical Sciences Institute, Durham University, Durham DH1 3LE, United Kingdom
- North East England Stem Cell Institute (NESCI), Newcastle Upon Tyne NE1 4EP, United Kingdom
| | - Adina D. Mihai
- Department of Biosciences, Durham University, Durham DH1 3LE, United Kingdom
- Biophysical Sciences Institute, Durham University, Durham DH1 3LE, United Kingdom
- North East England Stem Cell Institute (NESCI), Newcastle Upon Tyne NE1 4EP, United Kingdom
| | - Jamie N. Watson
- Department of Biosciences, Durham University, Durham DH1 3LE, United Kingdom
- Biophysical Sciences Institute, Durham University, Durham DH1 3LE, United Kingdom
- North East England Stem Cell Institute (NESCI), Newcastle Upon Tyne NE1 4EP, United Kingdom
| | - Robina Dendooven
- Department of Biosciences, Durham University, Durham DH1 3LE, United Kingdom
- Biophysical Sciences Institute, Durham University, Durham DH1 3LE, United Kingdom
- North East England Stem Cell Institute (NESCI), Newcastle Upon Tyne NE1 4EP, United Kingdom
| | - Adrienne W. Paton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia
| | - James C. Paton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia
| | - Martin Schröder
- Department of Biosciences, Durham University, Durham DH1 3LE, United Kingdom
- Biophysical Sciences Institute, Durham University, Durham DH1 3LE, United Kingdom
- North East England Stem Cell Institute (NESCI), Newcastle Upon Tyne NE1 4EP, United Kingdom
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14
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Miyata T, Hagiwara D, Hodai Y, Miwata T, Kawaguchi Y, Kurimoto J, Ozaki H, Mitsumoto K, Takagi H, Suga H, Kobayashi T, Sugiyama M, Onoue T, Ito Y, Iwama S, Banno R, Matsumoto M, Kawakami N, Ohno N, Sakamoto H, Arima H. Degradation of Mutant Protein Aggregates within the Endoplasmic Reticulum of Vasopressin Neurons. iScience 2020; 23:101648. [PMID: 33103081 PMCID: PMC7578753 DOI: 10.1016/j.isci.2020.101648] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 09/08/2020] [Accepted: 10/02/2020] [Indexed: 12/20/2022] Open
Abstract
Misfolded or unfolded proteins in the ER are said to be degraded only after translocation or isolation from the ER. Here, we describe a mechanism by which mutant proteins are degraded within the ER. Aggregates of mutant arginine vasopressin (AVP) precursor were confined to ER-associated compartments (ERACs) connected to the ER in AVP neurons of a mouse model of familial neurohypophysial diabetes insipidus. The ERACs were enclosed by membranes, an ER chaperone and marker protein of phagophores and autophagosomes were expressed around the aggregates, and lysosomes fused with the ERACs. Moreover, lysosome-related molecules were present within the ERACs, and aggregate degradation within the ERACs was dependent on autophagic-lysosomal activity. Thus, we demonstrate that protein aggregates can be degraded by autophagic-lysosomal machinery within specialized compartments of the ER. Mutant AVP precursors are confined to ERACs connected to the ER of FNDI AVP neurons Lysosomes fuse with ERACs surrounded by phagophore-like membranes Lysosome-related molecules are localized within ERACs Rapamycin reduces and chloroquine increases protein aggregate accumulation in ERACs
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Affiliation(s)
- Takashi Miyata
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Daisuke Hagiwara
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Yuichi Hodai
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Tsutomu Miwata
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Yohei Kawaguchi
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Junki Kurimoto
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Hajime Ozaki
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Kazuki Mitsumoto
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Hiroshi Takagi
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Hidetaka Suga
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Tomoko Kobayashi
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Mariko Sugiyama
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Takeshi Onoue
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Yoshihiro Ito
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Shintaro Iwama
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Ryoichi Banno
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.,Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya 464-8601, Japan
| | - Mami Matsumoto
- Section of Electron Microscopy, Supportive Center for Brain Research, National Institute for Physiological Sciences, Okazaki 444-8787, Japan
| | - Natsuko Kawakami
- Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, Setouchi 701-4303, Japan
| | - Nobuhiko Ohno
- Department of Anatomy, Division of Histology and Cell Biology, Jichi Medical University, School of Medicine, Shimotsuke 329-0498, Japan.,Division of Ultrastructural Research, National Institute for Physiological Sciences, Okazaki 444-8787, Japan
| | - Hirotaka Sakamoto
- Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, Setouchi 701-4303, Japan
| | - Hiroshi Arima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
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15
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Grandjean JMD, Madhavan A, Cech L, Seguinot BO, Paxman RJ, Smith E, Scampavia L, Powers ET, Cooley CB, Plate L, Spicer TP, Kelly JW, Wiseman RL. Pharmacologic IRE1/XBP1s activation confers targeted ER proteostasis reprogramming. Nat Chem Biol 2020; 16:1052-1061. [PMID: 32690944 PMCID: PMC7502540 DOI: 10.1038/s41589-020-0584-z] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 06/05/2020] [Indexed: 12/14/2022]
Abstract
Activation of the IRE1/XBP1s signaling arm of the unfolded protein response (UPR) is a promising strategy to correct defects in endoplasmic reticulum (ER) proteostasis implicated in diverse diseases. However, no pharmacologic activators of this pathway identified to date are suitable for ER proteostasis remodeling through selective activation of IRE1/XBP1s signaling. Here, we use high-throughput screening to identify non-toxic compounds that induce ER proteostasis remodeling through IRE1/XBP1s activation. We employ transcriptional profiling to stringently confirm that our prioritized compounds selectively activate IRE1/XBP1s signaling without activating other cellular stress-responsive signaling pathways. Furthermore, we demonstrate that our compounds improve ER proteostasis of destabilized variants of amyloid precursor protein (APP) through an IRE1-dependent mechanism and reduce APP-associated mitochondrial toxicity in cellular models. These results establish highly selective IRE1/XBP1s activating compounds that can be widely employed to define the functional importance of IRE1/XBP1s activity for ER proteostasis regulation in the context of health and disease.
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Affiliation(s)
- Julia M D Grandjean
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Aparajita Madhavan
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Lauren Cech
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Bryan O Seguinot
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Ryan J Paxman
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Emery Smith
- Scripps Research Molecular Screening Center, The Scripps Research Institute, Jupiter, FL, USA
| | - Louis Scampavia
- Scripps Research Molecular Screening Center, The Scripps Research Institute, Jupiter, FL, USA
| | - Evan T Powers
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | | | - Lars Plate
- Departments of Chemistry and Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Timothy P Spicer
- Scripps Research Molecular Screening Center, The Scripps Research Institute, Jupiter, FL, USA
| | - Jeffery W Kelly
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
- The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - R Luke Wiseman
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA.
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16
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Proteostasis regulators modulate proteasomal activity and gene expression to attenuate multiple phenotypes in Fabry disease. Biochem J 2020; 477:359-380. [PMID: 31899485 PMCID: PMC6993862 DOI: 10.1042/bcj20190513] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 12/17/2019] [Accepted: 01/02/2020] [Indexed: 12/22/2022]
Abstract
The lysosomal storage disorder Fabry disease is characterized by a deficiency of the lysosomal enzyme α-Galactosidase A. The observation that missense variants in the encoding GLA gene often lead to structural destabilization, endoplasmic reticulum retention and proteasomal degradation of the misfolded, but otherwise catalytically functional enzyme has resulted in the exploration of alternative therapeutic approaches. In this context, we have investigated proteostasis regulators (PRs) for their potential to increase cellular enzyme activity, and to reduce the disease-specific accumulation of the biomarker globotriaosylsphingosine in patient-derived cell culture. The PRs also acted synergistically with the clinically approved 1-deoxygalactonojirimycine, demonstrating the potential of combination treatment in a therapeutic application. Extensive characterization of the effective PRs revealed inhibition of the proteasome and elevation of GLA gene expression as paramount effects. Further analysis of transcriptional patterns of the PRs exposed a variety of genes involved in proteostasis as potential modulators. We propose that addressing proteostasis is an effective approach to discover new therapeutic targets for diseases involving folding and trafficking-deficient protein mutants.
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17
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Zhang Y, Lucius MD, Altomare D, Havighorst A, Farmaki E, Chatzistamou I, Shtutman M, Kiaris H. Coordination Analysis of Gene Expression Points to the Relative Impact of Different Regulators During Endoplasmic Reticulum Stress. DNA Cell Biol 2019; 38:969-981. [PMID: 31355672 DOI: 10.1089/dna.2019.4910] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Analysis of gene expression can be challenging, especially if it involves genetically diverse populations that exhibit high variation in their individual expression profile. Despite this variation, it is conceivable that in the same individuals a high degree of coordination is maintained between transcripts that belong to the same signaling modules and are associated with related biological functions. To explore this further, we calculated the correlation in the expression levels between each of ATF4, CHOP (DDIT3), GRP94, DNAJB9 (ERdj4), DNAJ3C (P58IPK), and HSPA5 (BiP/GRP78) with the whole transcriptome in primary fibroblasts from deer mice following induction of endoplasmic reticulum (ER) stress. Since these genes are associated with different transducers of the unfolded protein response (UPR), we postulated that their profile, in terms of correlation of transcripts, reflects distinct UPR branches engaged, and therefore different biological processes. Standard gene ontology analysis was able to predict major functions associated with the corresponding transcript, and of the UPR arm related to that, namely regulation of the apoptotic response by ATF4 (PERK arm) and the ER stress-associated degradation for GRP94 (IRE1). BiP, being a global regulator of the UPR, was associated with activation of ER stress in a rather global manner. Pairwise comparison in the correlation coefficients for these genes' associated transcriptome showed the relevance of selected genes in terms of expression profiles. Conventional assessment of differential gene expression was incapable of providing meaningful information and pointed only to a generic association with stress. Collectively, this approach suggests that by evaluating the degree of coordination in gene expression, in genetically diverse biological specimens, may be useful in assigning genes in transcriptome networks, and more importantly in linking signaling nodules to specific biological functions and processes.
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Affiliation(s)
- Youwen Zhang
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, South Carolina
| | - Matthew D Lucius
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, South Carolina
| | - Diego Altomare
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, South Carolina
| | - Amanda Havighorst
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, South Carolina
| | - Elena Farmaki
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, South Carolina
| | - Ioulia Chatzistamou
- Department of Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, South Carolina
| | - Michael Shtutman
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, South Carolina
| | - Hippokratis Kiaris
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, University of South Carolina, Columbia, South Carolina.,Peromyscus Genetic Stock Center, University of South Carolina, Columbia, South Carolina
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18
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Huang HW, Brown B, Chung J, Domingos PM, Ryoo HD. highroad Is a Carboxypetidase Induced by Retinoids to Clear Mutant Rhodopsin-1 in Drosophila Retinitis Pigmentosa Models. Cell Rep 2019; 22:1384-1391. [PMID: 29425495 PMCID: PMC5832065 DOI: 10.1016/j.celrep.2018.01.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Revised: 12/15/2017] [Accepted: 01/10/2018] [Indexed: 11/02/2022] Open
Abstract
Rhodopsins require retinoid chromophores for their function. In vertebrates, retinoids also serve as signaling molecules, but whether these molecules similarly regulate gene expression in Drosophila remains unclear. Here, we report the identification of a retinoid-inducible gene in Drosophila, highroad, which is required for photoreceptors to clear folding-defective mutant Rhodopsin-1 proteins. Specifically, knockdown or genetic deletion of highroad blocks the degradation of folding-defective Rhodopsin-1 mutant, ninaEG69D. Moreover, loss of highroad accelerates the age-related retinal degeneration phenotype of ninaEG69D mutants. Elevated highroad transcript levels are detected in ninaEG69D flies, and interestingly, deprivation of retinoids in the fly diet blocks this effect. Consistently, mutations in the retinoid transporter, santa maria, impairs the induction of highroad in ninaEG69D flies. In cultured S2 cells, highroad expression is induced by retinoic acid treatment. These results indicate that cellular quality-control mechanisms against misfolded Rhodopsin-1 involve regulation of gene expression by retinoids.
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Affiliation(s)
- Huai-Wei Huang
- Department of Cell Biology, New York University School of Medicine 550 First Avenue, New York, NY 10016, USA
| | - Brian Brown
- Department of Cell Biology, New York University School of Medicine 550 First Avenue, New York, NY 10016, USA
| | - Jaehoon Chung
- Department of Cell Biology, New York University School of Medicine 550 First Avenue, New York, NY 10016, USA
| | - Pedro M Domingos
- Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa, Av. da República, Oeiras 2780-157, Portugal
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine 550 First Avenue, New York, NY 10016, USA.
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19
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Grandjean JM, Plate L, Morimoto RI, Bollong MJ, Powers ET, Wiseman RL. Deconvoluting Stress-Responsive Proteostasis Signaling Pathways for Pharmacologic Activation Using Targeted RNA Sequencing. ACS Chem Biol 2019; 14:784-795. [PMID: 30821953 PMCID: PMC6474822 DOI: 10.1021/acschembio.9b00134] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cellular proteostasis is maintained by stress-responsive signaling pathways such as the heat shock response (HSR), the oxidative stress response (OSR), and the unfolded protein response (UPR). Activation of these pathways results in the transcriptional upregulation of select subsets of stress-responsive genes that restore proteostasis and adapt cellular physiology to promote recovery following various types of acute insult. The capacity for these pathways to regulate cellular proteostasis makes them attractive therapeutic targets for correcting proteostasis defects associated with diverse diseases. High-throughput screening (HTS) using cell-based reporter assays is highly effective for identifying putative activators of stress-responsive signaling pathways. However, the development of these compounds is hampered by the lack of medium-throughput assays to define compound potency and selectivity for a given pathway. Here, we describe a targeted RNA sequencing (RNAseq) assay that allows cost-effective, medium-throughput screening of stress-responsive signaling pathway activation. We demonstrate that this assay allows deconvolution of stress-responsive signaling activated by chemical genetic or pharmacologic agents. Furthermore, we use this assay to define the selectivity of putative OSR and HSR activating compounds previously identified by HTS. Our results demonstrate the potential for integrating this adaptable targeted RNAseq assay into screening programs focused on developing pharmacologic activators of stress-responsive signaling pathways.
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Affiliation(s)
- Julia M.D. Grandjean
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
| | - Lars Plate
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Richard I. Morimoto
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, IL, USA
| | - Michael J. Bollong
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - Evan T. Powers
- Department of Chemistry, The Scripps Research Institute, La Jolla, CA, USA
| | - R. Luke Wiseman
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, USA
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20
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Coupling of Human Rhodopsin to a Yeast Signaling Pathway Enables Characterization of Mutations Associated with Retinal Disease. Genetics 2018; 211:597-615. [PMID: 30514708 DOI: 10.1534/genetics.118.301733] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 11/29/2018] [Indexed: 12/24/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are crucial sensors of extracellular signals in eukaryotes, with multiple GPCR mutations linked to human diseases. With the growing number of sequenced human genomes, determining the pathogenicity of a mutation is challenging, but can be aided by a direct measurement of GPCR-mediated signaling. This is particularly difficult for the visual pigment rhodopsin-a GPCR activated by light-for which hundreds of mutations have been linked to inherited degenerative retinal diseases such as retinitis pigmentosa. In this study, we successfully engineered, for the first time, activation by human rhodopsin of the yeast mating pathway, resulting in signaling via a fluorescent reporter. We combine this novel assay for rhodopsin light-dependent activation with studies of subcellular localization, and the upregulation of the unfolded protein response in response to misfolded rhodopsin protein. We use these assays to characterize a panel of rhodopsin mutations with known molecular phenotypes, finding that rhodopsin maintains a similar molecular phenotype in yeast, with some interesting differences. Furthermore, we compare our assays in yeast with clinical phenotypes from patients with novel disease-linked mutations. We demonstrate that our engineered yeast strain can be useful in rhodopsin mutant classification, and in helping to determine the molecular mechanisms underlying their pathogenicity. This approach may also be applied to better understand the clinical relevance of other human GPCR mutations, furthering the use of yeast as a tool for investigating molecular mechanisms relevant to human disease.
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21
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Fu YL, Han DY, Wang YJ, Di XJ, Yu HB, Mu TW. Remodeling the endoplasmic reticulum proteostasis network restores proteostasis of pathogenic GABAA receptors. PLoS One 2018; 13:e0207948. [PMID: 30481215 PMCID: PMC6258528 DOI: 10.1371/journal.pone.0207948] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 11/08/2018] [Indexed: 01/12/2023] Open
Abstract
Biogenesis of membrane proteins is controlled by the protein homeostasis (proteostasis) network. We have been focusing on protein quality control of γ-aminobutyric acid type A (GABAA) receptors, the major inhibitory neurotransmitter-gated ion channels in mammalian central nervous system. Proteostasis deficiency in GABAA receptors causes loss of their surface expression and thus function on the plasma membrane, leading to epilepsy and other neurological diseases. One well-characterized example is the A322D mutation in the α1 subunit that causes its extensive misfolding and expedited degradation in the endoplasmic reticulum (ER), resulting in autosomal dominant juvenile myoclonic epilepsy. We aimed to correct misfolding of the α1(A322D) subunits in the ER as an approach to restore their functional surface expression. Here, we showed that application of BIX, a specific, potent ER resident HSP70 family protein BiP activator, significantly increases the surface expression of the mutant receptors in human HEK293T cells and neuronal SH-SY5Y cells. BIX attenuates the degradation of α1(A322D) and enhances their forward trafficking and function. Furthermore, because BiP is one major target of the two unfolded protein response (UPR) pathways: ATF6 and IRE1, we continued to demonstrate that modest activations of the ATF6 pathway and IRE1 pathway genetically enhance the plasma membrane trafficking of the α1(A322D) protein in HEK293T cells. Our results underlie the potential of regulating the ER proteostasis network to correct loss-of-function protein conformational diseases.
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Affiliation(s)
- Yan-Lin Fu
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Dong-Yun Han
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Ya-Juan Wang
- Center for Proteomics and Bioinformatics and Department of Epidemiology and Biostatistics, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Xiao-Jing Di
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - Hai-Bo Yu
- School of Chemistry and Molecular Bioscience & Molecular Horizons, University of Wollongong, Wollongong, Australia
| | - Ting-Wei Mu
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
- * E-mail:
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Yao J, Qiu Y, Frontera E, Jia L, Khan NW, Klionsky DJ, Ferguson TA, Thompson DA, Zacks DN. Inhibiting autophagy reduces retinal degeneration caused by protein misfolding. Autophagy 2018; 14:1226-1238. [PMID: 29940785 PMCID: PMC6103695 DOI: 10.1080/15548627.2018.1463121] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 04/02/2018] [Accepted: 04/04/2018] [Indexed: 12/13/2022] Open
Abstract
Mutations in the genes necessary for the structure and function of vertebrate photoreceptor cells are associated with multiple forms of inherited retinal degeneration. Mutations in the gene encoding RHO (rhodopsin) are a common cause of autosomal dominant retinitis pigmentosa (adRP), with the Pro23His variant of RHO resulting in a misfolded protein that activates endoplasmic reticulum stress and the unfolded protein response. Stimulating macroautophagy/autophagy has been proposed as a strategy for clearing misfolded RHO and reducing photoreceptor death. We found that retinas from mice heterozygous for the gene encoding the RHOP23H variant (hereafter called P23H) exhibited elevated levels of autophagy flux, and that pharmacological stimulation of autophagy accelerated retinal degeneration. In contrast, reducing autophagy flux pharmacologically or by rod-specific deletion of the autophagy-activating gene Atg5, improved photoreceptor structure and function. Furthermore, proteasome levels and activity were reduced in the P23H retina, and increased when Atg5 was deleted. Our findings suggest that autophagy contributes to photoreceptor cell death in P23H mice, and that decreasing autophagy shifts the degradation of misfolded RHO protein to the proteasome and is protective. These observations suggest that modulating the flux of misfolded proteins from autophagy to the proteasome may represent an important therapeutic strategy for reducing proteotoxicity in adRP and other diseases caused by protein folding defects.
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Affiliation(s)
- Jingyu Yao
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Yaoyan Qiu
- Department of Ophthalmology, Xiangya School of medicine, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Eric Frontera
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Lin Jia
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Naheed W. Khan
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, USA
| | | | - Thomas A. Ferguson
- Department of Ophthalmology and Visual Sciences, Washington University, St. Louis, MO, USA
| | - Debra A. Thompson
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, USA
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - David N. Zacks
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, USA
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Mishra R, Upadhyay A, Prajapati VK, Mishra A. Proteasome-mediated proteostasis: Novel medicinal and pharmacological strategies for diseases. Med Res Rev 2018; 38:1916-1973. [DOI: 10.1002/med.21502] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 03/13/2018] [Accepted: 04/04/2018] [Indexed: 02/06/2023]
Affiliation(s)
- Ribhav Mishra
- Cellular and Molecular Neurobiology Unit; Indian Institute of Technology Jodhpur; Rajasthan India
| | - Arun Upadhyay
- Cellular and Molecular Neurobiology Unit; Indian Institute of Technology Jodhpur; Rajasthan India
| | - Vijay Kumar Prajapati
- Department of Biochemistry; School of Life Sciences; Central University of Rajasthan; Rajasthan India
| | - Amit Mishra
- Cellular and Molecular Neurobiology Unit; Indian Institute of Technology Jodhpur; Rajasthan India
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LaVail MM, Nishikawa S, Steinberg RH, Naash MI, Duncan JL, Trautmann N, Matthes MT, Yasumura D, Lau-Villacorta C, Chen J, Peterson WM, Yang H, Flannery JG. Phenotypic characterization of P23H and S334ter rhodopsin transgenic rat models of inherited retinal degeneration. Exp Eye Res 2018; 167:56-90. [PMID: 29122605 PMCID: PMC5811379 DOI: 10.1016/j.exer.2017.10.023] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 10/25/2017] [Accepted: 10/31/2017] [Indexed: 02/07/2023]
Abstract
We produced 8 lines of transgenic (Tg) rats expressing one of two different rhodopsin mutations in albino Sprague-Dawley (SD) rats. Three lines were generated with a proline to histidine substitution at codon 23 (P23H), the most common autosomal dominant form of retinitis pigmentosa in the United States. Five lines were generated with a termination codon at position 334 (S334ter), resulting in a C-terminal truncated opsin protein lacking the last 15 amino acid residues and containing all of the phosphorylation sites involved in rhodopsin deactivation, as well as the terminal QVAPA residues important for rhodopsin deactivation and trafficking. The rates of photoreceptor (PR) degeneration in these models vary in proportion to the ratio of mutant to wild-type rhodopsin. The models have been widely studied, but many aspects of their phenotypes have not been described. Here we present a comprehensive study of the 8 Tg lines, including the time course of PR degeneration from the onset to one year of age, retinal structure by light and electron microscopy (EM), hemispheric asymmetry and gradients of rod and cone degeneration, rhodopsin content, gene dosage effect, rapid activation and invasion of the outer retina by presumptive microglia, rod outer segment disc shedding and phagocytosis by the retinal pigmented epithelium (RPE), and retinal function by the electroretinogram (ERG). The biphasic nature of PR cell death was noted, as was the lack of an injury-induced protective response in the rat models. EM analysis revealed the accumulation of submicron vesicular structures in the interphotoreceptor space during the peak period of PR outer segment degeneration in the S334ter lines. This is likely due to the elimination of the trafficking consensus domain as seen before as with other rhodopsin mutants lacking the C-terminal QVAPA. The 8 rhodopsin Tg lines have been, and will continue to be, extremely useful models for the experimental study of inherited retinal degenerations.
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Affiliation(s)
- Matthew M LaVail
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Shimpei Nishikawa
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Roy H Steinberg
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, 3517 Cullen Blvd., Room 2011, Houston, TX 77204-5060, USA.
| | - Jacque L Duncan
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Nikolaus Trautmann
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Michael T Matthes
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Douglas Yasumura
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA
| | - Cathy Lau-Villacorta
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Jeannie Chen
- Zilka Neurogenetic Institute, USC Keck School of Medicine, Los Angeles, CA 90089-2821, USA.
| | - Ward M Peterson
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - Haidong Yang
- Beckman Vision Center, University of California, San Francisco, San Francisco, CA 94143-0730, USA.
| | - John G Flannery
- School of Optometry, UC Berkeley, Berkeley, CA 94720-2020, USA.
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25
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Krebs MP, Collin GB, Hicks WL, Yu M, Charette JR, Shi LY, Wang J, Naggert JK, Peachey NS, Nishina PM. Mouse models of human ocular disease for translational research. PLoS One 2017; 12:e0183837. [PMID: 28859131 PMCID: PMC5578669 DOI: 10.1371/journal.pone.0183837] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 08/12/2017] [Indexed: 01/24/2023] Open
Abstract
Mouse models provide a valuable tool for exploring pathogenic mechanisms underlying inherited human disease. Here, we describe seven mouse models identified through the Translational Vision Research Models (TVRM) program, each carrying a new allele of a gene previously linked to retinal developmental and/or degenerative disease. The mutations include four alleles of three genes linked to human nonsyndromic ocular diseases (Aipl1tvrm119, Aipl1tvrm127, Rpgrip1tvrm111, RhoTvrm334) and three alleles of genes associated with human syndromic diseases that exhibit ocular phentoypes (Alms1tvrm102, Clcn2nmf289, Fkrptvrm53). Phenotypic characterization of each model is provided in the context of existing literature, in some cases refining our current understanding of specific disease attributes. These murine models, on fixed genetic backgrounds, are available for distribution upon request and may be useful for understanding the function of the gene in the retina, the pathological mechanisms induced by its disruption, and for testing experimental approaches to treat the corresponding human ocular diseases.
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Affiliation(s)
- Mark P. Krebs
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Gayle B. Collin
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Wanda L. Hicks
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Minzhong Yu
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
| | | | - Lan Ying Shi
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | - Jieping Wang
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
| | | | - Neal S. Peachey
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
- Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, United States of America
| | - Patsy M. Nishina
- The Jackson Laboratory, Bar Harbor, Maine, United States of America
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26
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Plate L, Wiseman RL. Regulating Secretory Proteostasis through the Unfolded Protein Response: From Function to Therapy. Trends Cell Biol 2017. [PMID: 28647092 DOI: 10.1016/j.tcb.2017.05.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Imbalances in secretory proteostasis induced by genetic, environmental, or aging-related insults are pathologically associated with etiologically diverse protein misfolding diseases. To protect the secretory proteome from these insults, organisms evolved stress-responsive signaling pathways that regulate the composition and activity of biologic pathways involved in secretory proteostasis maintenance. The most prominent of these is the endoplasmic reticulum (ER) unfolded protein response (UPR), which functions to regulate ER proteostasis in response to ER stress. While the signaling mechanisms involved in UPR activation are well defined, the impact of UPR activation on secretory proteostasis is only now becoming clear. Here, we highlight recent reports defining how activation of select UPR signaling pathways influences proteostasis within the ER and downstream secretory environments. Furthermore, we describe recent evidence that highlights the therapeutic potential for targeting UPR signaling pathways to correct pathologic disruption in secretory proteostasis associated with diverse types of protein misfolding diseases.
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Affiliation(s)
- Lars Plate
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - R Luke Wiseman
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
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27
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Kaufman DR, Papillon J, Larose L, Iwawaki T, Cybulsky AV. Deletion of inositol-requiring enzyme-1α in podocytes disrupts glomerular capillary integrity and autophagy. Mol Biol Cell 2017; 28:1636-1651. [PMID: 28428258 PMCID: PMC5469607 DOI: 10.1091/mbc.e16-12-0828] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 04/10/2017] [Accepted: 04/14/2017] [Indexed: 12/02/2022] Open
Abstract
Inositol-requiring enzyme-1α (IRE1α) is an endoplasmic reticulum (ER)-transmembrane endoribonuclease kinase that plays an essential function in extraembryonic tissues during normal development and is activated during ER stress. To address the functional role of IRE1α in glomerular podocytes, we produced podocyte-specific IRE1α-deletion mice. In male mice, deletion of IRE1α in podocytes resulted in albuminuria beginning at 5 mo of age and worsening with time. Electron microscopy revealed focal podocyte foot-process effacement in 9-mo-old male IRE1α-deletion mice, as well as microvillous transformation of podocyte plasma membranes. Compared with control, glomerular cross-sectional and capillary lumenal areas were greater in deletion mice, and there was relative podocyte depletion. Levels of microtubule-associated protein 1A/1B-light chain 3 (LC3)-II expression and c-Jun N-terminal kinase-1 phosphorylation were decreased in IRE1α-deletion glomeruli, in keeping with reduced autophagy. Deletion of IRE1α exacerbated glomerular injury in anti-glomerular basement membrane nephritis. In cell culture, IRE1α dominant-negative mutants reduced the physiological (basal) accumulation of LC3B-II and the size of autophagic vacuoles but did not affect ER-associated degradation. Thus IRE1α is essential for maintaining podocyte and glomerular integrity as mice age and in glomerulonephritis. The mechanism is related, at least in part, to the maintenance of autophagy in podocytes.
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Affiliation(s)
- Daniel Robert Kaufman
- Department of Physiology, McGill University, and McGill University Health Centre Research Institute, Montreal, QC H4A 3J1, Canada
| | - Joan Papillon
- Department of Medicine, McGill University, and McGill University Health Centre Research Institute, Montreal, QC H4A 3J1, Canada
| | - Louise Larose
- Department of Medicine, McGill University, and McGill University Health Centre Research Institute, Montreal, QC H4A 3J1, Canada
| | - Takao Iwawaki
- Department of Life Science, Medical Research Institute, Kanazawa Medical University, Uchinada 920-0293, Japan
| | - Andrey V Cybulsky
- Department of Physiology, McGill University, and McGill University Health Centre Research Institute, Montreal, QC H4A 3J1, Canada
- Department of Medicine, McGill University, and McGill University Health Centre Research Institute, Montreal, QC H4A 3J1, Canada
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28
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Palmitate mediated diacylglycerol accumulation causes endoplasmic reticulum stress, Plin2 degradation, and cell death in H9C2 cardiomyoblasts. Exp Cell Res 2017; 354:85-94. [DOI: 10.1016/j.yexcr.2017.03.032] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 03/13/2017] [Accepted: 03/14/2017] [Indexed: 12/22/2022]
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Neuroprotective Strategy in Retinal Degeneration: Suppressing ER Stress-Induced Cell Death via Inhibition of the mTOR Signal. Int J Mol Sci 2017; 18:ijms18010201. [PMID: 28106827 PMCID: PMC5297831 DOI: 10.3390/ijms18010201] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Revised: 01/13/2017] [Accepted: 01/16/2017] [Indexed: 12/11/2022] Open
Abstract
The retina is a specialized sensory organ, which is essential for light detection and visual formation in the human eye. Inherited retinal degenerations are a heterogeneous group of eye diseases that can eventually cause permanent vision loss. UPR (unfolded protein response) and ER (endoplasmic reticulum) stress plays an important role in the pathological mechanism of retinal degenerative diseases. mTOR (the mammalian target of rapamycin) kinase, as a signaling hub, controls many cellular processes, covering protein synthesis, RNA translation, ER stress, and apoptosis. Here, the hypothesis that inhibition of mTOR signaling suppresses ER stress-induced cell death in retinal degenerative disorders is discussed. This review surveys knowledge of the influence of mTOR signaling on ER stress arising from misfolded proteins and genetic mutations in retinal degenerative diseases and highlights potential neuroprotective strategies for treatment and therapeutic implications.
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30
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Nevo N, Thomas L, Chhuon C, Andrzejewska Z, Lipecka J, Guillonneau F, Bailleux A, Edelman A, Antignac C, Guerrera IC. Impact of Cystinosin Glycosylation on Protein Stability by Differential Dynamic Stable Isotope Labeling by Amino Acids in Cell Culture (SILAC). Mol Cell Proteomics 2017; 16:457-468. [PMID: 28082515 DOI: 10.1074/mcp.m116.063867] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/11/2017] [Indexed: 11/06/2022] Open
Abstract
Cystinosis is a rare autosomal recessive lysosomal storage disorder characterized by intralysosomal accumulation of cystine. The causative gene for cystinosis is CTNS, which encodes the protein cystinosin, a lysosomal proton-driven cystine transporter. Over 100 mutations have been reported, leading to varying disease severity, often in correlation with residual cystinosin activity as a transporter and with maintenance of its protein-protein interactions. In this study, we focus on the ΔITILELP mutation, the only mutation reported that sometimes leads to severe forms, inconsistent with its residual transported activity. ΔITILELP is a deletion that eliminates a consensus site on N66, one of the protein's seven glycosylation sites. Our hypothesis was that the ΔITILELP mutant is less stable and undergoes faster degradation. Our dynamic stable isotope labeling by amino acids in cell culture (SILAC) study clearly showed that wild-type cystinosin is very stable, whereas ΔITILELP is degraded three times more rapidly. Additional lysosome inhibition experiments confirmed ΔITILELP instability and showed that the degradation was mainly lysosomal. We observed that in the lysosome, ΔITILELP is still capable of interacting with the V-ATPase complex and some members of the mTOR pathway, similar to the wild-type protein. Intriguingly, our interactomic and immunofluorescence studies showed that ΔITILELP is partially retained at the endoplasmic reticulum (ER). We proposed that the ΔITILELP mutation causes protein misfolding, ER retention and inability to be processed in the Golgi apparatus, and we demonstrated that ΔITILELP carries high-mannose glycans on all six of its remaining glycosylation sites. We found that the high turnover of ΔITILELP, because of its immature glycosylation state in combination with low transport activity, might be responsible for the phenotype observed in some patients.
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Affiliation(s)
- Nathalie Nevo
- From the ‡INSERM U1163, Laboratory of Hereditary Kidney Diseases, Imagine Institute, Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Lucie Thomas
- From the ‡INSERM U1163, Laboratory of Hereditary Kidney Diseases, Imagine Institute, Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Cerina Chhuon
- §Plateforme Protéomique Paris Descartes Necker, PPN, 3P5-Necker, SFR Necker, US24, 75014 Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Zuzanna Andrzejewska
- From the ‡INSERM U1163, Laboratory of Hereditary Kidney Diseases, Imagine Institute, Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Joanna Lipecka
- ¶The CPN Proteomics Facility - 3P5, Center of Psychiatry and Neuroscience, UMR INSERM 894, 75014 Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - François Guillonneau
- ‖Plateforme Protéomique Paris Descartes Cochin, 3P5-Cochin, 75014 Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Anne Bailleux
- From the ‡INSERM U1163, Laboratory of Hereditary Kidney Diseases, Imagine Institute, Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Aleksander Edelman
- §Plateforme Protéomique Paris Descartes Necker, PPN, 3P5-Necker, SFR Necker, US24, 75014 Paris, France.,**INSERM U1151, 75015 Paris, France
| | - Corinne Antignac
- From the ‡INSERM U1163, Laboratory of Hereditary Kidney Diseases, Imagine Institute, Paris, France.,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France.,§§Assistance Publique - Hôpitaux de Paris (AP-HP), Department of Genetics, Necker Hospital, Paris, France
| | - Ida Chiara Guerrera
- §Plateforme Protéomique Paris Descartes Necker, PPN, 3P5-Necker, SFR Necker, US24, 75014 Paris, France; .,‡‡Paris Descartes-Sorbonne Paris Cité University, Paris, France
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31
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In vivo Editing of the Human Mutant Rhodopsin Gene by Electroporation of Plasmid-based CRISPR/Cas9 in the Mouse Retina. MOLECULAR THERAPY. NUCLEIC ACIDS 2016; 5:e389. [PMID: 27874856 PMCID: PMC5155324 DOI: 10.1038/mtna.2016.92] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 09/01/2016] [Indexed: 12/22/2022]
Abstract
The bacterial CRISPR/Cas system has proven to be an efficient tool for genetic manipulation in various organisms. Here we show the application of CRISPR-Cas9 technology to edit the human Rhodopsin (RHO) gene in a mouse model for autosomal dominant Retinitis Pigmentosa. We designed single or double sgRNAs to knock-down mutant RHO expression by targeting exon 1 of the RHO gene carrying the P23H dominant mutation. By delivering Cas9 and sgRNAs in a single plasmid we induced an efficient gene editing in vitro, in HeLa cells engineered to constitutively express the P23H mutant RHO allele. Similarly, after subretinal electroporation of the CRISPR/Cas9 plasmid expressing two sgRNAs into P23H RHO transgenic mice, we scored specific gene editing as well as significant reduction of the mutant RHO protein. Successful in vivo application of the CRISPR/Cas9 system confirms its efficacy as a genetic engineering tool in photoreceptor cells.
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Bogéa TH, Wen RH, Moritz OL. Light Induces Ultrastructural Changes in Rod Outer and Inner Segments, Including Autophagy, in a Transgenic Xenopus laevis P23H Rhodopsin Model of Retinitis Pigmentosa. Invest Ophthalmol Vis Sci 2016; 56:7947-55. [PMID: 26720441 DOI: 10.1167/iovs.15-16799] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE We previously reported a transgenic Xenopus laevis model of retinitis pigmentosa in which tadpoles express the bovine form of P23H rhodopsin (bP23H) in rod photoreceptors. In this model, retinal degeneration was dependent on light exposure. Here, we investigated ultrastructural changes that occurred in the rod photoreceptors of these retinas when exposed to light. METHODS Tadpoles expressing bP23H in rods were transferred from constant darkness to a 12-hour light:12-hour dark (12L:12D) regimen. For comparison, transgenic tadpoles expressing an inducible form of caspase 9 (iCasp9) were reared in a 12L:12D regimen, and retinal degeneration was induced by administration of the drug AP20187. Tadpoles were euthanized at various time points, and eyes were processed for confocal light and transmission electron microscopy. RESULTS We observed defects in outer and inner segments of rods expressing bP23H that were aggravated by light exposure. Rod outer segments exhibited vesiculations throughout and were rapidly phagocytosed by the retinal pigment epithelium. In rod inner segments, we observed autophagic compartments adjacent to the endoplasmic reticulum and extensive vesiculation at later time points. These defects were not found in rods expressing iCasp9, which completely degenerated within 36 hours after drug administration. CONCLUSIONS Our results indicate that ultrastructural defects in outer and inner segment membranes of bP23H expressing rods differ from those observed in drug-induced apoptosis. We suggest that light-induced retinal degeneration caused by P23H rhodopsin occurs via cell death with autophagy, which may represent an attempt to eliminate the mutant rhodopsin and/or damaged cellular compartments from the secretory pathway.
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33
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Chan P, Stolz J, Kohl S, Chiang WC, Lin JH. Endoplasmic reticulum stress in human photoreceptor diseases. Brain Res 2016; 1648:538-541. [PMID: 27117871 DOI: 10.1016/j.brainres.2016.04.021] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 04/08/2016] [Accepted: 04/09/2016] [Indexed: 11/18/2022]
Abstract
Photoreceptors are specialized sensory neurons essential for light detection in the human eye. Photoreceptor cell dysfunction and death cause vision loss in many eye diseases such as retinitis pigmentosa and achromatopsia. Endoplasmic reticulum (ER) stress and Unfolded Protein Response (UPR) signaling have been implicated in the development and pathology of heritable forms of retinitis pigmentosa and achromatopsia. We review the role of ER stress and UPR in retinitis pigmentosa arising from misfolded rhodopsins (RHO) and in achromatopsia arising from genetic mutations in Activating Transcription Factor 6 (ATF6). This article is part of a Special Issue entitled SI:ER stress.
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Affiliation(s)
- Priscilla Chan
- Pathology, University of California, San Diego, La Jolla, CA, United States
| | - Julia Stolz
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Susanne Kohl
- Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany
| | - Wei-Chieh Chiang
- Pathology, University of California, San Diego, La Jolla, CA, United States
| | - Jonathan H Lin
- Pathology, University of California, San Diego, La Jolla, CA, United States.
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34
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Lobo GP, Au A, Kiser PD, Hagstrom SA. Involvement of Endoplasmic Reticulum Stress in TULP1 Induced Retinal Degeneration. PLoS One 2016; 11:e0151806. [PMID: 26987071 PMCID: PMC4795779 DOI: 10.1371/journal.pone.0151806] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 03/04/2016] [Indexed: 11/18/2022] Open
Abstract
Inherited retinal disorders (IRDs) result in severe visual impairments in children and adults. A challenge in the field of retinal degenerations is identifying mechanisms of photoreceptor cell death related to specific genetic mutations. Mutations in the gene TULP1 have been associated with two forms of IRDs, early-onset retinitis pigmentosa (RP) and Leber congenital amaurosis (LCA). TULP1 is a cytoplasmic, membrane-associated protein shown to be involved in transportation of newly synthesized proteins destined for the outer segment compartment of photoreceptor cells; however, how mutant TULP1 causes cell death is not understood. In this study, we provide evidence that common missense mutations in TULP1 express as misfolded protein products that accumulate within the endoplasmic reticulum (ER) causing prolonged ER stress. In an effort to maintain protein homeostasis, photoreceptor cells then activate the unfolded protein response (UPR) complex. Our results indicate that the two major apoptotic arms of the UPR pathway, PERK and IRE1, are activated. Additionally, we show that retinas expressing mutant TULP1 significantly upregulate the expression of CHOP, a UPR signaling protein promoting apoptosis, and undergo photoreceptor cell death. Our study demonstrates that the ER-UPR, a known mechanism of apoptosis secondary to an overwhelming accumulation of misfolded protein, is involved in photoreceptor degeneration caused by missense mutations in TULP1. These observations suggest that modulating the UPR pathways might be a strategy for therapeutic intervention.
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Affiliation(s)
- Glenn P. Lobo
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, 44195, United States of America
| | - Adrian Au
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, 44195, United States of America
| | - Philip D. Kiser
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, 44106, United States of America
- Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, 44106, United States of America
| | - Stephanie A. Hagstrom
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, 44195, United States of America
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, 44195, United States of America
- * E-mail:
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35
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Baranczak A, Kelly JW. A current pharmacologic agent versus the promise of next generation therapeutics to ameliorate protein misfolding and/or aggregation diseases. Curr Opin Chem Biol 2016; 32:10-21. [PMID: 26859714 DOI: 10.1016/j.cbpa.2016.01.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 01/14/2016] [Accepted: 01/14/2016] [Indexed: 12/18/2022]
Abstract
The list of protein aggregation-associated degenerative diseases is long and growing, while the portfolio of disease-modifying strategies is very small. In this review and perspective, we assess what has worked to slow the progression of an aggregation-associated degenerative disease, covering the underlying mechanism of pharmacologic action and what we have learned about the etiology of the transthyretin amyloid diseases and likely amyloidoses in general. Next, we introduce emerging therapies that should apply more generally to protein misfolding and/or aggregation diseases, approaches that rely on adapting the protein homeostasis or proteostasis network for disease amelioration.
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Affiliation(s)
- Aleksandra Baranczak
- Department of Chemistry and The Skaggs Institute for Chemical Biology, La Jolla, CA 92037, USA; Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | - Jeffery W Kelly
- Department of Chemistry and The Skaggs Institute for Chemical Biology, La Jolla, CA 92037, USA; Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
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Chiang WC, Joseph V, Yasumura D, Matthes MT, Lewin AS, Gorbatyuk MS, Ahern K, LaVail MM, Lin JH. Ablation of Chop Transiently Enhances Photoreceptor Survival but Does Not Prevent Retinal Degeneration in Transgenic Mice Expressing Human P23H Rhodopsin. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 854:185-91. [PMID: 26427410 DOI: 10.1007/978-3-319-17121-0_25] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
RHO (Rod opsin) encodes a G-protein coupled receptor that is expressed exclusively by rod photoreceptors of the retina and forms the essential photopigment, rhodopsin, when coupled with 11-cis-retinal. Many rod opsin disease -mutations cause rod opsin protein misfolding and trigger endoplasmic reticulum (ER) stress, leading to activation of the Unfolded Protein Response (UPR) signal transduction network. Chop is a transcriptional activator that is induced by ER stress and promotes cell death in response to chronic ER stress. Here, we examined the role of Chop in transgenic mice expressing human P23H rhodopsin (hP23H Rho Tg) that undergo retinal degeneration. With the exception of one time point, we found no significant induction of Chop in these animals and no significant change in retinal degeneration by histology and electrophysiology when hP23H Rho Tg animals were bred into a Chop (-/-) background. Our results indicate that Chop does not play a significant causal role during retinal degeneration in these animals. We suggest that other modules of the ER stress-induced UPR signaling network may be involved photoreceptor disease induced by P23H rhodopsin.
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Affiliation(s)
- Wei-Chieh Chiang
- Department of Pathology, University of California, La Jolla, 92093, San Diego, CA, USA.
| | - Victory Joseph
- Department of Pathology, University of California, La Jolla, 92093, San Diego, CA, USA.
| | - Douglas Yasumura
- Department of Ophthalmology, University of California, 94143, San Francisco, CA, USA
| | - Michael T Matthes
- Department of Ophthalmology, University of California, 94143, San Francisco, CA, USA.
| | - Alfred S Lewin
- Department of Molecular Genetics and Microbiology, University of Florida, 32610, Gainesville, FL, USA.
| | - Marina S Gorbatyuk
- Department of Vision Sciences, University of Alabama at Birmingham, 35294, Birmingham, AL, USA.
| | - Kelly Ahern
- Department of Ophthalmology, University of California, 94143, San Francisco, CA, USA.
| | - Matthew M LaVail
- Departments of Anatomy and Ophthalmology, University of California, 94143, San Francisco, CA, USA.
| | - Jonathan H Lin
- Department of Pathology, University of California, La Jolla, 92093, San Diego, CA, USA. .,VA San Diego Healthcare System, 92161, San Diego, CA, USA.
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Lodowski KH, Imanishi Y. Monitoring of rhodopsin trafficking and mistrafficking in live photoreceptors. Methods Mol Biol 2015; 1271:293-307. [PMID: 25697531 DOI: 10.1007/978-1-4939-2330-4_19] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Outer segment (OS) directed trafficking is required for accomplishing the extremely high concentration of rhodopsin and explicitly high photon sensitivity of rod photoreceptor cells. Aberrant targeting of rhodopsin often leads to blinding disorders, due to various mechanisms causing rhodopsin mislocalization. Until recently, it has been challenging to monitor the dynamics of rhodopsin biogenesis and trafficking. Here, we describe a new method to visualize rhodopsin trafficking in living and unfixed Xenopus laevis rod photoreceptors. By harnessing the photochemical property of a photoconvertible fluorescent protein Dendra2, it is now possible to encode temporal information into colors and resolve spatiotemporal distribution of rhodopsin-Dendra2 fusion proteins in individual rod photoreceptors.
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Affiliation(s)
- Kerrie H Lodowski
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106-4965, USA
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Lamech LT, Haynes CM. The unpredictability of prolonged activation of stress response pathways. J Cell Biol 2015; 209:781-7. [PMID: 26101215 PMCID: PMC4477854 DOI: 10.1083/jcb.201503107] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
In response to stress, cellular compartments activate signaling pathways that mediate transcriptional programs to promote survival and reestablish homeostasis. Manipulation of the magnitude and duration of the activation of stress responses has been proposed as a strategy to prevent or repair the damage associated with aging or degenerative diseases. However, as these pathways likely evolved to respond specifically to transient perturbations, the unpredictability of prolonged activation should be considered.
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Affiliation(s)
- Lilian T Lamech
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065
| | - Cole M Haynes
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065 BCMB Allied Program, Weill Cornell Medical College, New York, NY 10065
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Hiramatsu N, Chiang WC, Kurt TD, Sigurdson CJ, Lin JH. Multiple Mechanisms of Unfolded Protein Response-Induced Cell Death. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 185:1800-8. [PMID: 25956028 PMCID: PMC4484218 DOI: 10.1016/j.ajpath.2015.03.009] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 02/09/2015] [Accepted: 03/26/2015] [Indexed: 12/12/2022]
Abstract
Eukaryotic cells fold and assemble membrane and secreted proteins in the endoplasmic reticulum (ER), before delivery to other cellular compartments or the extracellular environment. Correctly folded proteins are released from the ER, and poorly folded proteins are retained until they achieve stable conformations; irreparably misfolded proteins are targeted for degradation. Diverse pathological insults, such as amino acid mutations, hypoxia, or infection, can overwhelm ER protein quality control, leading to misfolded protein buildup, causing ER stress. To cope with ER stress, eukaryotic cells activate the unfolded protein response (UPR) by increasing levels of ER protein-folding enzymes and chaperones, enhancing the degradation of misfolded proteins, and reducing protein translation. In mammalian cells, three ER transmembrane proteins, inositol-requiring enzyme-1 (IRE1; official name ERN1), PKR-like ER kinase (PERK; official name EIF2AK3), and activating transcription factor-6, control the UPR. The UPR signaling triggers a set of prodeath programs when the cells fail to successfully adapt to ER stress or restore homeostasis. ER stress and UPR signaling are implicated in the pathogenesis of diverse diseases, including neurodegeneration, cancer, diabetes, and inflammation. This review discusses the current understanding in both adaptive and apoptotic responses as well as the molecular mechanisms instigating apoptosis via IRE1 and PERK signaling. We also examine how IRE1 and PERK signaling may be differentially used during neurodegeneration arising in retinitis pigmentosa and prion infection.
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Affiliation(s)
- Nobuhiko Hiramatsu
- Department of Pathology, University of California-San Diego, La Jolla, California
| | - Wei-Chieh Chiang
- Department of Pathology, University of California-San Diego, La Jolla, California
| | - Timothy D Kurt
- Department of Pathology, University of California-San Diego, La Jolla, California
| | | | - Jonathan H Lin
- Department of Pathology, University of California-San Diego, La Jolla, California.
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Chen JJ, Genereux JC, Wiseman RL. Endoplasmic reticulum quality control and systemic amyloid disease: Impacting protein stability from the inside out. IUBMB Life 2015; 67:404-13. [PMID: 26018985 DOI: 10.1002/iub.1386] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 04/27/2015] [Indexed: 11/11/2022]
Abstract
The endoplasmic reticulum (ER) is responsible for regulating proteome integrity throughout the secretory pathway. The ER protects downstream secretory environments such as the extracellular space by partitioning proteins between ER protein folding, trafficking, and degradation pathways in a process called ER quality control. In this process, ER quality control factors identify misfolded, aggregation-prone protein conformations and direct them toward ER protein folding or degradation, reducing their secretion to the extracellular space where they could further misfold or aggregate into proteotoxic conformations. Despite the general efficiency of ER quality control, many human diseases, such as the systemic amyloidoses, involve aggregation of destabilized, aggregation-prone proteins in the extracellular space. A common feature for all systemic amyloid diseases is the ability for amyloidogenic proteins to evade ER quality control and be efficiently secreted. The efficient secretion of these amyloidogenic proteins increases their serum concentrations available for the distal proteotoxic aggregation characteristic of these diseases. This indicates that ER quality control, and the regulation thereof, is a critical determinant in defining the onset and pathology of systemic amyloid diseases. Here, we discuss the pathologic and potential therapeutic relationship between ER quality control, protein secretion, and distal deposition of amyloidogenic proteins involved in systemic amyloid diseases. Furthermore, we present evidence that the unfolded protein response, the stress-responsive signaling pathway that regulates ER quality control, is involved in the pathogenesis of systemic amyloid diseases and represents a promising emerging therapeutic target to intervene in this class of human disease.
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Affiliation(s)
- John J Chen
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA.,Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Joseph C Genereux
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA.,Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, USA
| | - R Luke Wiseman
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA, USA.,Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA, USA
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Trzcińska-Daneluti AM, Chen A, Nguyen L, Murchie R, Jiang C, Moffat J, Pelletier L, Rotin D. RNA Interference Screen to Identify Kinases That Suppress Rescue of ΔF508-CFTR. Mol Cell Proteomics 2015; 14:1569-83. [PMID: 25825526 DOI: 10.1074/mcp.m114.046375] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Indexed: 01/08/2023] Open
Abstract
Cystic Fibrosis (CF) is an autosomal recessive disorder caused by mutations in the gene encoding the Cystic fibrosis transmembrane conductance regulator (CFTR). ΔF508-CFTR, the most common disease-causing CF mutant, exhibits folding and trafficking defects and is retained in the endoplasmic reticulum, where it is targeted for proteasomal degradation. To identify signaling pathways involved in ΔF508-CFTR rescue, we screened a library of endoribonuclease-prepared short interfering RNAs (esiRNAs) that target ∼750 different kinases and associated signaling proteins. We identified 20 novel suppressors of ΔF508-CFTR maturation, including the FGFR1. These were subsequently validated by measuring channel activity by the YFP halide-sensitive assay following shRNA-mediated knockdown, immunoblotting for the mature (band C) ΔF508-CFTR and measuring the amount of surface ΔF508-CFTR by ELISA. The role of FGFR signaling on ΔF508-CFTR trafficking was further elucidated by knocking down FGFRs and their downstream signaling proteins: Erk1/2, Akt, PLCγ-1, and FRS2. Interestingly, inhibition of FGFR1 with SU5402 administered to intestinal organoids (mini-guts) generated from the ileum of ΔF508-CFTR homozygous mice resulted in a robust ΔF508-CFTR rescue. Moreover, combination of SU5402 and VX-809 treatments in cells led to an additive enhancement of ΔF508-CFTR rescue, suggesting these compounds operate by different mechanisms. Chaperone array analysis on human bronchial epithelial cells harvested from ΔF508/ΔF508-CFTR transplant patients treated with SU5402 identified altered expression of several chaperones, an effect validated by their overexpression or knockdown experiments. We propose that FGFR signaling regulates specific chaperones that control ΔF508-CFTR maturation, and suggest that FGFRs may serve as important targets for therapeutic intervention for the treatment of CF.
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Affiliation(s)
- Agata M Trzcińska-Daneluti
- From the ‡Program in Cell Biology, The Hospital for Sick Children, Toronto, and Biochemistry Department, University of Toronto; PGCRL, 19-9715, 686 Bay St., Toronto, Ont., Canada, M5G 0A4
| | - Anthony Chen
- From the ‡Program in Cell Biology, The Hospital for Sick Children, Toronto, and Biochemistry Department, University of Toronto; PGCRL, 19-9715, 686 Bay St., Toronto, Ont., Canada, M5G 0A4
| | - Leo Nguyen
- From the ‡Program in Cell Biology, The Hospital for Sick Children, Toronto, and Biochemistry Department, University of Toronto; PGCRL, 19-9715, 686 Bay St., Toronto, Ont., Canada, M5G 0A4
| | - Ryan Murchie
- From the ‡Program in Cell Biology, The Hospital for Sick Children, Toronto, and Biochemistry Department, University of Toronto; PGCRL, 19-9715, 686 Bay St., Toronto, Ont., Canada, M5G 0A4
| | - Chong Jiang
- From the ‡Program in Cell Biology, The Hospital for Sick Children, Toronto, and Biochemistry Department, University of Toronto; PGCRL, 19-9715, 686 Bay St., Toronto, Ont., Canada, M5G 0A4
| | | | | | - Daniela Rotin
- From the ‡Program in Cell Biology, The Hospital for Sick Children, Toronto, and Biochemistry Department, University of Toronto; PGCRL, 19-9715, 686 Bay St., Toronto, Ont., Canada, M5G 0A4
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Jiang H, Xiong S, Xia X. Chemical chaperone 4-phenylbutyrate prevents endoplasmic reticulum stress induced by T17M rhodopsin. Cell Biosci 2014; 4:75. [PMID: 25530840 PMCID: PMC4271335 DOI: 10.1186/2045-3701-4-75] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 11/25/2014] [Indexed: 11/30/2022] Open
Abstract
Background Rhodopsin mutations are associated with the autosomal dominant form of retinitis pigmentosa. T17M mutation in rhodopsin predisposes cells to endoplasmic reticulum (ER) stress and induces cell death. This study aimed to examine whether chemical chaperone 4-phenylbutyrate prevents ER stress induced by rhodopsin T17M. Results ARPE-19 cells were transfected with myc-tagged wild-type (WT) and T17M rhodopsin constructs. Turnover of WT and T17M rhodopsin was measured by cycloheximide chase analysis. The activity of ubiquitin-proteasome system was evaluated by GFPU reporter. We found that T17M rhodopsin was misfolded, ubiqutinated and eliminated by ER-associated degradation pathway (ERAD) in ARPE-19 cells. Accumulated T17M rhodopsin induced unfolded protein response, but had no effect on the activity of ubiquitin proteasome system. Moreover, chemical chaperone 4-phenylbutyrate facilitated the turnover of T17M rhodopsin and prevented apoptosis and ER stress induced by T17M rhodopsin. Conclusions Chemical chaperone could attenuate UPR signaling and ER stress induced by T17M rhodopsin and has potential therapeutic significance for retinitis pigmentosa.
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Affiliation(s)
- Haibo Jiang
- Department of Ophthalmology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan 410078 P.R. China
| | - Siqi Xiong
- Department of Ophthalmology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan 410078 P.R. China
| | - Xiaobo Xia
- Department of Ophthalmology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan 410078 P.R. China
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Azuma Y, Hagiwara D, Lu W, Morishita Y, Suga H, Goto M, Banno R, Sugimura Y, Oyadomari S, Mori K, Shiota A, Asai N, Takahashi M, Oiso Y, Arima H. Activating transcription factor 6α is required for the vasopressin neuron system to maintain water balance under dehydration in male mice. Endocrinology 2014; 155:4905-14. [PMID: 25203138 DOI: 10.1210/en.2014-1522] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Activating transcription factor 6α (ATF6α) is a sensor of endoplasmic reticulum (ER) stress and increases the expression of ER chaperones and molecules related to the ER-associated degradation of unfolded/misfolded proteins. In this study, we used ATF6α knockout (ATF6α(-/-)) mice to clarify the role of ATF6α in the arginine vasopressin (AVP) neuron system. Although urine volumes were not different between ATF6α(-/-) and wild-type (ATF6α(+/+)) mice with access to water ad libitum, they were increased in ATF6α(-/-) mice compared with those in ATF6α(+/+) mice under intermittent water deprivation (WD) and accompanied by less urine AVP in ATF6α(-/-) mice. The mRNA expression of immunoglobulin heavy chain binding protein, an ER chaperone, was significantly increased in the supraoptic nucleus in ATF6α(+/+) but not ATF6α(-/-) mice after WD. Electron microscopic analyses demonstrated that the ER lumen of AVP neurons was more dilated in ATF6α(-/-) mice than in ATF6α(+/+) mice after WD. ATF6α(-/-) mice that were mated with mice possessing a mutation causing familial neurohypophysial diabetes insipidus (FNDI), which is characterized by progressive polyuria and AVP neuronal loss due to the accumulation of mutant AVP precursor in the ER, manifested increased urine volume under intermittent WD. The aggregate formation in the ER of AVP neurons was further impaired in FNDI/ATF6α(-/-) mice compared with that in FNDI mice, and AVP neuronal loss was accelerated in FNDI/ATF6α(-/-) mice under WD. These data suggest that ATF6α is required for the AVP neuron system to maintain water balance under dehydration.
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Affiliation(s)
- Yoshinori Azuma
- Departments of Endocrinology and Diabetes (Y.A., D.H., W.L., Y.M., H.S., M.G., R.B., Y.S., Y.O., H.A.) and Pathology (N.A., M.T.), Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan; Institute of Immunology Co., Ltd (A.S.), 1198-4 Iwazo, Utsunomiya 321-0973, Japan; Institute for Genome Research (S.O.), University of Tokushima, Tokushima 770-8503, Japan; and Department of Biophysics (K.M.), Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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Chiang WC, Kroeger H, Sakami S, Messah C, Yasumura D, Matthes MT, Coppinger JA, Palczewski K, LaVail MM, Lin JH. Robust Endoplasmic Reticulum-Associated Degradation of Rhodopsin Precedes Retinal Degeneration. Mol Neurobiol 2014; 52:679-95. [PMID: 25270370 DOI: 10.1007/s12035-014-8881-8] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 08/25/2014] [Indexed: 12/18/2022]
Abstract
Rhodopsin is a G protein-coupled receptor essential for vision and rod photoreceptor viability. Disease-associated rhodopsin mutations, such as P23H rhodopsin, cause rhodopsin protein misfolding and trigger endoplasmic reticulum (ER) stress, activating the unfolded protein response (UPR). The pathophysiologic effects of ER stress and UPR activation on photoreceptors are unclear. Here, by examining P23H rhodopsin knock-in mice, we found that the UPR inositol-requiring enzyme 1 (IRE1) signaling pathway is strongly activated in misfolded rhodopsin-expressing photoreceptors. IRE1 significantly upregulated ER-associated protein degradation (ERAD), triggering pronounced P23H rhodopsin degradation. Rhodopsin protein loss occurred as soon as photoreceptors developed, preceding photoreceptor cell death. By contrast, IRE1 activation did not affect JNK signaling or rhodopsin mRNA levels. Interestingly, pro-apoptotic signaling from the PERK UPR pathway was also not induced. Our findings reveal that an early and significant pathophysiologic effect of ER stress in photoreceptors is the highly efficient elimination of misfolded rhodopsin protein. We propose that early disruption of rhodopsin protein homeostasis in photoreceptors could contribute to retinal degeneration.
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Affiliation(s)
- Wei-Chieh Chiang
- Department of Pathology, University of California, San Diego, 9500 Gilman Dr., La Jolla, San Diego, CA, 92093-0612, USA
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Scott PA, Fernandez de Castro JP, Kaplan HJ, McCall MA. A Pro23His mutation alters prenatal rod photoreceptor morphology in a transgenic swine model of retinitis pigmentosa. Invest Ophthalmol Vis Sci 2014; 55:2452-9. [PMID: 24618321 DOI: 10.1167/iovs.13-13723] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
PURPOSE Functional studies have detected deficits in retinal signaling in asymptomatic children from families with inherited autosomal dominant retinitis pigmentosa (RP). Whether retinal abnormalities are present earlier during gestation or shortly after birth in a subset of children with autosomal dominant RP is unknown and no appropriate animal RP model possessing visual function at birth has been available to examine this possibility. In a recently developed transgenic P23H (TgP23H) rhodopsin swine model of RP, we tracked changes in pre- and early postnatal retinal morphology, as well as early postnatal retinal function. METHODS Domestic swine inseminated with semen from a TgP23H miniswine founder produced TgP23H hybrid and wild type (Wt) littermates. Outer retinal morphology was assessed at light and electron microscopic levels between embryonic (E) and postnatal (P) day E85 to P3. Retinal function was evaluated using the full field electroretinogram at P3. RESULTS Embryonic TgP23H rod photoreceptors are malformed and their rhodopsin expression pattern is abnormal. Consistent with morphological abnormalities, rod-driven function is absent at P3. In contrast, TgP23H and Wt cone photoreceptor morphology (E85-P3) and cone-driven retinal function (P3) are similar. CONCLUSIONS Prenatal expression of mutant rhodopsin alters the normal morphological and functional development of rod photoreceptors in TgP23H swine embryos. Despite this significant change, cone photoreceptors are unaffected. Human infants with similarly aggressive RP might never have rod vision, although cone vision would be unaffected. Such aggressive forms of RP in preverbal children would require early intervention to delay or prevent functional blindness.
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Affiliation(s)
- Patrick A Scott
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky, United States
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Hiramatsu N, Messah C, Han J, LaVail MM, Kaufman RJ, Lin JH. Translational and posttranslational regulation of XIAP by eIF2α and ATF4 promotes ER stress-induced cell death during the unfolded protein response. Mol Biol Cell 2014; 25:1411-20. [PMID: 24623724 PMCID: PMC4004591 DOI: 10.1091/mbc.e13-11-0664] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Chronic ER stress down-regulates XIAP by activating the PERK branch of the UPR. PERK attenuates Xiap translation via eIF2α phosphorylation. PERK promotes XIAP degradation via ATF4. CHOP induction and XIAP suppression act in parallel to sensitize cells to ER stress–induced apoptosis. Endoplasmic reticulum (ER) protein misfolding activates the unfolded protein response (UPR) to help cells cope with ER stress. If ER homeostasis is not restored, UPR promotes cell death. The mechanisms of UPR-mediated cell death are poorly understood. The PKR-like endoplasmic reticulum kinase (PERK) arm of the UPR is implicated in ER stress–induced cell death, in part through up-regulation of proapoptotic CCAAT/enhancer binding protein homologous protein (CHOP). Chop−/− cells are partially resistant to ER stress–induced cell death, and CHOP overexpression alone does not induce cell death. These findings suggest that additional mechanisms regulate cell death downstream of PERK. Here we find dramatic suppression of antiapoptosis XIAP proteins in response to chronic ER stress. We find that PERK down-regulates XIAP synthesis through eIF2α and promotes XIAP degradation through ATF4. Of interest, PERK's down-regulation of XIAP occurs independently of CHOP activity. Loss of XIAP leads to increased cell death, whereas XIAP overexpression significantly enhances resistance to ER stress–induced cell death, even in the absence of CHOP. Our findings define a novel signaling circuit between PERK and XIAP that operates in parallel with PERK to CHOP induction to influence cell survival during ER stress. We propose a “two-hit” model of ER stress–induced cell death involving concomitant CHOP up-regulation and XIAP down-regulation both induced by PERK.
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Affiliation(s)
- Nobuhiko Hiramatsu
- Department of Pathology, University of California at San Diego, La Jolla, CA 92093 Center for Neuroscience, Aging, and Stem Cell Research, Sanford Burnham Medical Research Institute, La Jolla, CA 92037 Departments of Anatomy and Ophthalmology, University of California at San Francisco, San Francisco, CA 94143
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Kroeger H, LaVail MM, Lin JH. Endoplasmic reticulum stress in vertebrate mutant rhodopsin models of retinal degeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:585-92. [PMID: 24664747 DOI: 10.1007/978-1-4614-3209-8_74] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Rhodopsin mutations cause many types of heritable retinitis pigmentosa (RP). Biochemical and in vitro studies have demonstrated that many RP-linked mutant rhodopsins produce misfolded rhodopsin proteins, which are prone to aggregation and retention within the endoplasmic reticulum, where they cause endoplasmic reticulum stress and activate the Unfolded Protein Response signaling pathways. Many vertebrate models of retinal degeneration have been created through expression of RP-linked rhodopsins in photoreceptors including, but not limited to, VPP/GHL mice, P23H Rhodopsin frogs, P23H rhodopsin rats, S334ter rhodopsin rats, C185R rhodopsin mice, T17M rhodopsin mice, and P23H rhodopsin mice. These models have provided many opportunities to test therapeutic strategies to prevent retinal degeneration and also enabled in vivo investigation of cellular and molecular mechanisms responsible for photoreceptor cell death. Here, we examine and compare the contribution of endoplasmic reticulum stress to retinal degeneration in several vertebrate models of RP generated through expression of mutant rhodopsins.
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Affiliation(s)
- Heike Kroeger
- Department of Pathology, University of California, San Diego, USA,
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Jerry Chiang WC, Lin JH. The effects of IRE1, ATF6, and PERK signaling on adRP-linked rhodopsins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:661-7. [PMID: 24664756 DOI: 10.1007/978-1-4614-3209-8_83] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Many mutations in rhodopsin gene linked to retinitis pigmentosa (RP) cause rhodopsin misfolding. Rod photoreceptor cells expressing misfolded rhodopsin eventually die. Identifying mechanisms to prevent rhodopsin misfolding or to remove irreparably misfolded rhodopsin could provide new therapeutic strategies. IRE1, ATF6, and PERK signaling pathways, collectively called the unfolded protein response (UPR), regulate the functions of endoplasmic reticulum, responsible for accurate folding of membrane proteins such as rhodopsin. We used chemical and genetic approaches to selectively activate IRE1, ATF6, or PERK signaling pathways one at a time and analyzed their effects on mutant rhodopsin linked to RP. We found that both artificial IRE1 and ATF6 signaling promoted the degradation of mutant rhodopsin with lesser effects on wild-type rhodopsin. Furthermore, IRE1 and ATF6 signaling preferentially reduced levels of aggregated rhodopsins. By contrast, PERK signaling reduced levels of wild-type and mutant rhodopsin. These studies indicate that activation of either IRE1, ATF6, or PERK prevents mutant rhodopsin from accumulating in the cells. In addition, activation of IRE1 or ATF6 can selectively remove aggregated or mutant rhodopsin from the cells and may be useful in treating RP associated with rhodopsin protein misfolding.
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Affiliation(s)
- Wei-Chieh Jerry Chiang
- Department of Pathology, University of California at San Diego, 9500 Gilman Dr., 92093-0612, La Jolla, CA, USA,
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Gorbatyuk M, Gorbatyuk O. Review: retinal degeneration: focus on the unfolded protein response. Mol Vis 2013; 19:1985-98. [PMID: 24068865 PMCID: PMC3782367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 09/18/2013] [Indexed: 11/08/2022] Open
Abstract
Recently published literature has provided evidence that the unfolded protein response (UPR) is involved in the development of retinal degeneration. The scope of these studies encompassed diabetic retinopathy, retinopathy of prematurity, glaucoma, retinal detachment, light-induced retinal degeneration, age-related macular degeneration, and inherited retinal degeneration. Subsequent studies investigating the role of individual UPR markers in retinal pathogenesis and examining the therapeutic potential of reprogramming the UPR as a method for modulating the rate of retinal degeneration have been initiated. Manipulation of UPR markers has been made possible by the use of knockout mice, pharmacological agents, and viral vector-mediated augmentation of gene expression. Future research will aim at identifying specific inhibitors and/or inducers of UPR regulatory markers as well as expand the list of UPR-related animal models. Additionally, adeno-associated virus-mediated gene delivery is a safe and effective method for modulating gene expression, and thus is a useful research tool for manipulating individual UPR markers in affected retinas and a promising delivery vector for gene therapy in retinal degenerative disorders.
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Affiliation(s)
- Marina Gorbatyuk
- Department of Vision Sciences, University of Alabama at Birmingham, Birmingham, AL 35233
| | - Oleg Gorbatyuk
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610
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Athanasiou D, Aguilà M, Bevilacqua D, Novoselov SS, Parfitt DA, Cheetham ME. The cell stress machinery and retinal degeneration. FEBS Lett 2013; 587:2008-17. [PMID: 23684651 PMCID: PMC4471140 DOI: 10.1016/j.febslet.2013.05.020] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 05/01/2013] [Accepted: 05/02/2013] [Indexed: 12/12/2022]
Abstract
Retinal degenerations are a group of clinically and genetically heterogeneous disorders characterised by progressive loss of vision due to neurodegeneration. The retina is a highly specialised tissue with a unique architecture and maintaining homeostasis in all the different retinal cell types is crucial for healthy vision. The retina can be exposed to a variety of environmental insults and stress, including light-induced damage, oxidative stress and inherited mutations that can lead to protein misfolding. Within retinal cells there are different mechanisms to cope with disturbances in proteostasis, such as the heat shock response, the unfolded protein response and autophagy. In this review, we discuss the multiple responses of the retina to different types of stress involved in retinal degenerations, such as retinitis pigmentosa, age-related macular degeneration and glaucoma. Understanding the mechanisms that maintain and re-establish proteostasis in the retina is important for developing new therapeutic approaches to fight blindness.
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Affiliation(s)
| | - Monica Aguilà
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Dalila Bevilacqua
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | | | - David A. Parfitt
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
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