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Nakatsukasa K, Wigge S, Takano Y, Kawarasaki T, Kamura T, Brodsky JL. A positive genetic selection for transmembrane domain mutations in HRD1 underscores the importance of Hrd1 complex integrity during ERAD. Curr Genet 2022; 68:227-242. [PMID: 35041076 PMCID: PMC9036396 DOI: 10.1007/s00294-022-01227-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 12/29/2021] [Accepted: 12/30/2021] [Indexed: 11/26/2022]
Abstract
Misfolded proteins in the endoplasmic reticulum (ER) are retrotranslocated to the cytosol for ubiquitination and degradation by the proteasome. During this process, known as ER-associated degradation (ERAD), the ER-embedded Hrd1 ubiquitin ligase plays a central role in recognizing, ubiquitinating, and retrotranslocating scores of lumenal and integral membrane proteins. To better define the mechanisms underlying Hrd1 function in Saccharomyces cerevisiae, several model substrates have been developed. One substrate is Sec61-2, a temperature sensitive allele of the Sec61 translocation channel. Cells expressing Sec61-2 grow at 25 °C because the protein is stable, but sec61-2 yeast are inviable at 38 °C because the mutated protein is degraded in a Hrd1-dependent manner. Therefore, deleting HRD1 stabilizes Sec61-2 and hence sec61-2hrd1∆ double mutants are viable at 38 °C. This unique phenotype allowed us to perform a non-biased screen for loss-of-function alleles in HRD1. Based on its importance in mediating substrate retrotranslocation, the screen was also developed to focus on mutations in sequences encoding Hrd1's transmembrane-rich domain. Ultimately, a group of recessive mutations was identified in HRD1, including an ensemble of destabilizing mutations that resulted in the delivery of Hrd1 to the ERAD pathway. A more stable mutant resided in a buried transmembrane domain, yet the Hrd1 complex was disrupted in yeast expressing this mutant. Together, these data confirm the importance of Hrd1 complex integrity during ERAD, suggest that allosteric interactions between transmembrane domains regulate Hrd1 complex formation, and provide the field with new tools to define the dynamic interactions between ERAD components during substrate retrotranslocation.
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Affiliation(s)
- Kunio Nakatsukasa
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi, 467-8501, Japan.
| | - Sylvia Wigge
- Department of Biological Sciences, University of Pittsburgh, A320 Langley Hall, Pittsburgh, PA, 15260, USA
| | - Yuki Takano
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi, 467-8501, Japan
| | - Tomoyuki Kawarasaki
- Graduate School of Science, Nagoya City University, Yamanohata 1, Mizuho-cho, Mizuho-ku, Nagoya, Aichi, 467-8501, Japan
| | - Takumi Kamura
- Division of Biological Sciences, Graduate School of Science, Nagoya University, Nagoya, Aichi, 464-8602, Japan
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, A320 Langley Hall, Pittsburgh, PA, 15260, USA.
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52
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Borgert L, Mishra S, den Brave F. Quality control of cytoplasmic proteins inside the nucleus. Comput Struct Biotechnol J 2022; 20:4618-4625. [PMID: 36090811 PMCID: PMC9440239 DOI: 10.1016/j.csbj.2022.08.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 08/13/2022] [Accepted: 08/15/2022] [Indexed: 11/03/2022] Open
Abstract
A complex network of molecular chaperones and proteolytic machinery safeguards the proteins which comprise the proteome, from the time they are synthesized on ribosomes to their destruction via proteolysis. Impaired protein quality control results in the accumulation of aberrant proteins, which may undergo unwanted spurious interactions with other proteins, thereby interfering with a broad range of cellular functions. To protect the cellular environment, such proteins are degraded or sequestered into inclusions in different subcellular compartments. Recent findings demonstrate that aberrant or mistargeted proteins from different cytoplasmic compartments are removed from their environment by transporting them into the nucleus. These proteins are degraded by the nuclear ubiquitin–proteasome system or sequestered into intra-nuclear inclusions. Here, we discuss the emerging role of the nucleus as a cellular quality compartment based on recent findings in the yeast Saccharomyces cerevisiae. We describe the current knowledge on cytoplasmic substrates of nuclear protein quality control, the mechanism of nuclear import of such proteins, as well as possible advantages and risks of nuclear sequestration of aberrant proteins.
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53
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Smith CE, Tsai YC, Liang YH, Khago D, Mariano J, Li J, Tarasov SG, Gergel E, Tsai B, Villaneuva M, Clapp ME, Magidson V, Chari R, Byrd RA, Ji X, Weissman AM. A structurally conserved site in AUP1 binds the E2 enzyme UBE2G2 and is essential for ER-associated degradation. PLoS Biol 2021; 19:e3001474. [PMID: 34879065 PMCID: PMC8699718 DOI: 10.1371/journal.pbio.3001474] [Citation(s) in RCA: 8] [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: 02/01/2021] [Revised: 12/23/2021] [Accepted: 11/05/2021] [Indexed: 12/22/2022] Open
Abstract
Endoplasmic reticulum-associated degradation (ERAD) is a protein quality control pathway of fundamental importance to cellular homeostasis. Although multiple ERAD pathways exist for targeting topologically distinct substrates, all pathways require substrate ubiquitination. Here, we characterize a key role for the UBE2G2 Binding Region (G2BR) of the ERAD accessory protein ancient ubiquitous protein 1 (AUP1) in ERAD pathways. This 27-amino acid (aa) region of AUP1 binds with high specificity and low nanomolar affinity to the backside of the ERAD ubiquitin-conjugating enzyme (E2) UBE2G2. The structure of the AUP1 G2BR (G2BRAUP1) in complex with UBE2G2 reveals an interface that includes a network of salt bridges, hydrogen bonds, and hydrophobic interactions essential for AUP1 function in cells. The G2BRAUP1 shares significant structural conservation with the G2BR found in the E3 ubiquitin ligase gp78 and in vitro can similarly allosterically activate ubiquitination in conjunction with ERAD E3s. In cells, AUP1 is uniquely required to maintain normal levels of UBE2G2; this is due to G2BRAUP1 binding to the E2 and preventing its rapid degradation. In addition, the G2BRAUP1 is required for both ER membrane recruitment of UBE2G2 and for its activation at the ER membrane. Thus, by binding to the backside of a critical ERAD E2, G2BRAUP1 plays multiple critical roles in ERAD.
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Affiliation(s)
- Christopher E. Smith
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Yien Che Tsai
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Yu-He Liang
- Center for Structural Biology, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Domarin Khago
- Center for Structural Biology, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Jennifer Mariano
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Jess Li
- Center for Structural Biology, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Sergey G. Tarasov
- Center for Structural Biology, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Emma Gergel
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Borong Tsai
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Matthew Villaneuva
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Michelle E. Clapp
- Genome Modification Core, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Valentin Magidson
- Optical Microscopy and Analysis Laboratory, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Raj Chari
- Genome Modification Core, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - R. Andrew Byrd
- Center for Structural Biology, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Xinhua Ji
- Center for Structural Biology, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
| | - Allan M. Weissman
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, NCI, National Institutes of Health, Frederick, Maryland, United States of America
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Nejatfard A, Wauer N, Bhaduri S, Conn A, Gourkanti S, Singh N, Kuo T, Kandel R, Amaro RE, Neal SE. Derlin rhomboid pseudoproteases employ substrate engagement and lipid distortion to enable the retrotranslocation of ERAD membrane substrates. Cell Rep 2021; 37:109840. [PMID: 34686332 PMCID: PMC8641752 DOI: 10.1016/j.celrep.2021.109840] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 07/19/2021] [Accepted: 09/27/2021] [Indexed: 01/13/2023] Open
Abstract
Nearly one-third of proteins are initially targeted to the endoplasmic reticulum (ER) membrane, where they are correctly folded and then delivered to their final cellular destinations. To prevent the accumulation of misfolded membrane proteins, ER-associated degradation (ERAD) moves these clients from the ER membrane to the cytosol, a process known as retrotranslocation. Our recent work in Saccharomyces cerevisiae reveals a derlin rhomboid pseudoprotease, Dfm1, is involved in the retrotranslocation of ubiquitinated ERAD membrane substrates. In this study, we identify conserved residues of Dfm1 that are critical for retrotranslocation. We find several retrotranslocation-deficient Loop 1 mutants that display impaired binding to membrane substrates. Furthermore, Dfm1 possesses lipid thinning function to facilitate in the removal of ER membrane substrates, and this feature is conserved in its human homolog, Derlin-1, further implicating that derlin-mediated retrotranslocation is a well-conserved process.
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Affiliation(s)
- Anahita Nejatfard
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Nicholas Wauer
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093, USA
| | - Satarupa Bhaduri
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Adam Conn
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Saroj Gourkanti
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Narinderbir Singh
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Tiffany Kuo
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Rachel Kandel
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Rommie E Amaro
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093, USA
| | - Sonya E Neal
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA.
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Wu Q, Tian JH, He YX, Huang YY, Huang YQ, Zhang GP, Luo JD, Xue Q, Yu XY, Liu YH. Zonisamide alleviates cardiac hypertrophy in rats by increasing Hrd1 expression and inhibiting endoplasmic reticulum stress. Acta Pharmacol Sin 2021; 42:1587-1597. [PMID: 33495518 PMCID: PMC8463597 DOI: 10.1038/s41401-020-00585-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 11/17/2020] [Indexed: 02/02/2023] Open
Abstract
Antiepileptic drug zonisamide has been shown to be curative for Parkinson's disease (PD) through increasing HMG-CoA reductase degradation protein 1 (Hrd1) level and mitigating endoplasmic reticulum (ER) stress. Hrd1 is an ER-transmembrane E3 ubiquitin ligase, which is involved in cardiac dysfunction and cardiac hypertrophy in a mouse model of pressure overload. In this study, we investigated whether zonisamide alleviated cardiac hypertrophy in rats by increasing Hrd1 expression and inhibiting ER stress. The beneficial effects of zonisamide were assessed in two experimental models of cardiac hypertrophy: in rats subjected to abdominal aorta constriction (AAC) and treated with zonisamide (14, 28, 56 mg · kg-1 · d-1, i.g.) for 6 weeks as well as in neonatal rat cardiomyocytes (NRCMs) co-treated with Ang II (10 μM) and zonisamide (0.3 μM). Echocardiography analysis revealed that zonsiamide treatment significantly improved cardiac function in AAC rats. We found that zonsiamide treatment significantly attenuated cardiac hypertrophy and fibrosis, and suppressed apoptosis and ER stress in the hearts of AAC rats and in Ang II-treated NRCMs. Importantly, zonisamide markedly increased the expression of Hrd1 in the hearts of AAC rats and in Ang II-treated NRCMs. Furthermore, we demonstrated that zonisamide accelerated ER-associated protein degradation (ERAD) in Ang II-treated NRCMs; knockdown of Hrd1 abrogated the inhibitory effects of zonisamide on ER stress and cardiac hypertrophy. Taken together, our results demonstrate that zonisamide is effective in preserving heart structure and function in the experimental models of pathological cardiac hypertrophy. Zonisamide increases Hrd1 expression, thus preventing cardiac hypertrophy and improving the cardiac function of AAC rats.
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Affiliation(s)
- Qian Wu
- The Fifth Affiliated Hospital, Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Jia-Hui Tian
- The Fifth Affiliated Hospital, Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Yong-Xiang He
- The Fifth Affiliated Hospital, Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Yong-Yin Huang
- The Fifth Affiliated Hospital, Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Yu-Qing Huang
- The Fifth Affiliated Hospital, Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Gui-Ping Zhang
- The Fifth Affiliated Hospital, Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Jian-Dong Luo
- The Fifth Affiliated Hospital, Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Qin Xue
- The Fifth Affiliated Hospital, Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou, 511436, China.
| | - Xi-Yong Yu
- The Fifth Affiliated Hospital, Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou, 511436, China.
| | - Ying-Hua Liu
- The Fifth Affiliated Hospital, Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences, Guangzhou Medical University, Guangzhou, 511436, China.
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56
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Singh R, Smit RB, Wang X, Wang C, Racher H, Hansen D. Reduction of Derlin activity suppresses Notch-dependent tumours in the C. elegans germ line. PLoS Genet 2021; 17:e1009687. [PMID: 34555015 PMCID: PMC8491880 DOI: 10.1371/journal.pgen.1009687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 10/05/2021] [Accepted: 09/08/2021] [Indexed: 11/19/2022] Open
Abstract
Regulating the balance between self-renewal (proliferation) and differentiation is key to the long-term functioning of all stem cell pools. In the Caenorhabditis elegans germline, the primary signal controlling this balance is the conserved Notch signaling pathway. Gain-of-function mutations in the GLP-1/Notch receptor cause increased stem cell self-renewal, resulting in a tumour of proliferating germline stem cells. Notch gain-of-function mutations activate the receptor, even in the presence of little or no ligand, and have been associated with many human diseases, including cancers. We demonstrate that reduction in CUP-2 and DER-2 function, which are Derlin family proteins that function in endoplasmic reticulum-associated degradation (ERAD), suppresses the C. elegans germline over-proliferation phenotype associated with glp-1(gain-of-function) mutations. We further demonstrate that their reduction does not suppress other mutations that cause over-proliferation, suggesting that over-proliferation suppression due to loss of Derlin activity is specific to glp-1/Notch (gain-of-function) mutations. Reduction of CUP-2 Derlin activity reduces the expression of a read-out of GLP-1/Notch signaling, suggesting that the suppression of over-proliferation in Derlin loss-of-function mutants is due to a reduction in the activity of the mutated GLP-1/Notch(GF) receptor. Over-proliferation suppression in cup-2 mutants is only seen when the Unfolded Protein Response (UPR) is functioning properly, suggesting that the suppression, and reduction in GLP-1/Notch signaling levels, observed in Derlin mutants may be the result of activation of the UPR. Chemically inducing ER stress also suppress glp-1(gf) over-proliferation but not other mutations that cause over-proliferation. Therefore, ER stress and activation of the UPR may help correct for increased GLP-1/Notch signaling levels, and associated over-proliferation, in the C. elegans germline. Notch signaling is a highly conserved signaling pathway that is utilized in many cell fate decisions in many organisms. In the C. elegans germline, Notch signaling is the primary signal that regulates the balance between stem cell proliferation and differentiation. Notch gain-of-function mutations cause the receptor to be active, even when a signal that is normally needed to activate the receptor is absent. In the germline of C. elegans, gain-of-function mutations in GLP-1, a Notch receptor, results in over-proliferation of the stem cells and tumour formation. Here we demonstrate that a reduction or loss of Derlin activity, which is a conserved family of proteins involved in endoplasmic reticulum-associated degradation (ERAD), suppresses over-proliferation due to GLP-1/Notch gain-of-function mutations. Furthermore, we demonstrate that a surveillance mechanism utilized in cells to monitor and react to proteins that are not folded properly (Unfolded Protein Response-UPR) must be functioning well in order for the loss of Derlin activity to supress over-proliferation caused by glp-1/Notch gain-of-function mutations. This suggests that activation of the UPR may be the mechanism at work for suppressing this type of over-proliferation, when Derlin activity is reduced. Therefore, decreasing Derlin activity may be a means of reducing the impact of phenotypes and diseases due to certain Notch gain-of-function mutations.
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Affiliation(s)
- Ramya Singh
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Ryan B. Smit
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Xin Wang
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Chris Wang
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Hilary Racher
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Dave Hansen
- Department of Biological Sciences, University of Calgary, Calgary, Canada
- * E-mail:
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Sun Z, Guerriero CJ, Brodsky JL. Substrate ubiquitination retains misfolded membrane proteins in the endoplasmic reticulum for degradation. Cell Rep 2021; 36:109717. [PMID: 34551305 PMCID: PMC8503845 DOI: 10.1016/j.celrep.2021.109717] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 06/11/2021] [Accepted: 08/25/2021] [Indexed: 11/28/2022] Open
Abstract
To maintain secretory pathway fidelity, misfolded proteins are commonly retained in the endoplasmic reticulum (ER) and selected for ER-associated degradation (ERAD). Soluble misfolded proteins use ER chaperones for retention, but the machinery that restricts aberrant membrane proteins to the ER is unclear. In fact, some misfolded membrane proteins escape the ER and traffic to the lysosome/vacuole. To this end, we describe a model substrate, SZ*, that contains an ER export signal but is also targeted for ERAD. We observe decreased ER retention when chaperone-dependent SZ* ubiquitination is compromised. In addition, appending a linear tetra-ubiquitin motif onto SZ* overrides ER export. By screening known ubiquitin-binding proteins, we then positively correlate SZ* retention with Ubx2 binding. Deletion of Ubx2 also inhibits the retention of another misfolded membrane protein. Our results indicate that polyubiquitination is sufficient to retain misfolded membrane proteins in the ER prior to ERAD. Sun et al. characterize how misfolded membrane proteins are delivered for either ERAD or post-ER degradation in the secretory pathway. By using a model substrate that can access both pathways, they show that substrate retention requires chaperone-dependent substrate ubiquitination and interaction with a conserved ER membrane protein, Ubx2.
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Affiliation(s)
- Zhihao Sun
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | | | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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Liu F, Zhao H, Kong R, Shi L, Li Z, Ma R, Zhao H, Li Z. Derlin-1 and TER94/VCP/p97 are required for intestinal homeostasis. J Genet Genomics 2021; 49:195-207. [PMID: 34547438 DOI: 10.1016/j.jgg.2021.08.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 08/15/2021] [Accepted: 08/19/2021] [Indexed: 12/30/2022]
Abstract
Adult stem cells are critical for the maintenance of residential tissue homeostasis and functions. However, the roles of cellular protein homeostasis maintenance in stem cell proliferation and tissue homeostasis are not fully understood. Here, we find that Derlin-1 and TER94/VCP/p97, components of the ER-associated degradation (ERAD) pathway, restrain intestinal stem cell proliferation to maintain intestinal homeostasis in adult Drosophila. Depleting any of them results in increased stem cell proliferation and midgut homeostasis disruption. Derlin-1 is specifically expressed in the ER of progenitors and its C-terminus is required for its function. Interestingly, we find that increased stem cell proliferation is resulted from elevated ROS levels and activated JNK signaling in Derlin-1- or TER94-deficient progenitors. Further removal of ROS or inhibition of JNK signaling almost completely suppressed increased stem cell proliferation. Together, these data demonstrate that the ERAD pathway is critical for stem cell proliferation and tissue homeostasis. Thus we provide insights into our understanding of the mechanisms underlying cellular protein homeostasis maintenance (ER protein quality control) in tissue homeostasis and tumor development.
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Affiliation(s)
- Fuli Liu
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Hang Zhao
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Ruiyan Kong
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Lin Shi
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zhengran Li
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Rui Ma
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
| | - Huiqing Zhao
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Zhouhua Li
- College of Life Sciences, Capital Normal University, Beijing 100048, China.
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59
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CREBH Systemically Regulates Lipid Metabolism by Modulating and Integrating Cellular Functions. Nutrients 2021; 13:nu13093204. [PMID: 34579081 PMCID: PMC8472586 DOI: 10.3390/nu13093204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 09/13/2021] [Accepted: 09/13/2021] [Indexed: 12/11/2022] Open
Abstract
Cyclic AMP-responsive element-binding protein H (CREBH, encoded by CREB3L3) is a membrane-bound transcriptional factor expressed in the liver and small intestine. The activity of CREBH is regulated not only at the transcriptional level but also at the posttranslational level. CREBH governs triglyceride metabolism in the liver by controlling gene expression, with effects including the oxidation of fatty acids, lipophagy, and the expression of apolipoproteins related to the lipoprotein lipase activation and suppression of lipogenesis. The activation and functions of CREBH are controlled in response to the circadian rhythm. On the other hand, intestinal CREBH downregulates the absorption of lipids from the diet. CREBH deficiency in mice leads to severe hypertriglyceridemia and fatty liver in the fasted state and while feeding a high-fat diet. Therefore, when crossing CREBH knockout (KO) mice with an atherosclerosis model, low-density lipoprotein receptor KO mice, these mice exhibit severe atherosclerosis. This phenotype is seen in both liver- and small intestine-specific CREBH KO mice, suggesting that CREBH controls lipid homeostasis in an enterohepatic interaction. This review highlights that CREBH has a crucial role in systemic lipid homeostasis to integrate cellular functions related to lipid metabolism.
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60
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Blandin CE, Gravez BJ, Hatem SN, Balse E. Remodeling of Ion Channel Trafficking and Cardiac Arrhythmias. Cells 2021; 10:cells10092417. [PMID: 34572065 PMCID: PMC8468138 DOI: 10.3390/cells10092417] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 09/08/2021] [Accepted: 09/11/2021] [Indexed: 01/08/2023] Open
Abstract
Both inherited and acquired cardiac arrhythmias are often associated with the abnormal functional expression of ion channels at the cellular level. The complex machinery that continuously traffics, anchors, organizes, and recycles ion channels at the plasma membrane of a cardiomyocyte appears to be a major source of channel dysfunction during cardiac arrhythmias. This has been well established with the discovery of mutations in the genes encoding several ion channels and ion channel partners during inherited cardiac arrhythmias. Fibrosis, altered myocyte contacts, and post-transcriptional protein changes are common factors that disorganize normal channel trafficking during acquired cardiac arrhythmias. Channel availability, described notably for hERG and KV1.5 channels, could be another potent arrhythmogenic mechanism. From this molecular knowledge on cardiac arrhythmias will emerge novel antiarrhythmic strategies.
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Affiliation(s)
- Camille E. Blandin
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
| | - Basile J. Gravez
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
| | - Stéphane N. Hatem
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
- ICAN—Institute of Cardiometabolism and Nutrition, Institute of Cardiology, Pitié-Salpêtrière Hospital, Sorbonne University, F-75013 Paris, France
| | - Elise Balse
- INSERM, Unité de Recherche sur les Maladies Cardiovasculaires, le Métabolisme et la Nutrition—UNITE 1166, Sorbonne Université, EQUIPE 3, F-75013 Paris, France; (C.E.B.); (B.J.G.); (S.N.H.)
- Correspondence:
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The Targeting of Native Proteins to the Endoplasmic Reticulum-Associated Degradation (ERAD) Pathway: An Expanding Repertoire of Regulated Substrates. Biomolecules 2021; 11:biom11081185. [PMID: 34439852 PMCID: PMC8393694 DOI: 10.3390/biom11081185] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/05/2021] [Accepted: 08/08/2021] [Indexed: 12/22/2022] Open
Abstract
All proteins are subject to quality control processes during or soon after their synthesis, and these cellular quality control pathways play critical roles in maintaining homeostasis in the cell and in organism health. Protein quality control is particularly vital for those polypeptides that enter the endoplasmic reticulum (ER). Approximately one-quarter to one-third of all proteins synthesized in eukaryotic cells access the ER because they are destined for transport to the extracellular space, because they represent integral membrane proteins, or because they reside within one of the many compartments of the secretory pathway. However, proteins that mature inefficiently are subject to ER-associated degradation (ERAD), a multi-step pathway involving the chaperone-mediated selection, ubiquitination, and extraction (or “retrotranslocation”) of protein substrates from the ER. Ultimately, these substrates are degraded by the cytosolic proteasome. Interestingly, there is an increasing number of native enzymes and metabolite and solute transporters that are also targeted for ERAD. While some of these proteins may transiently misfold, the ERAD pathway also provides a route to rapidly and quantitatively downregulate the levels and thus the activities of a variety of proteins that mature or reside in the ER.
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Kim H, Wei J, Song Z, Mottillo E, Samavati L, Zhang R, Li L, Chen X, Jena BP, Lin JD, Fang D, Zhang K. Regulation of hepatic circadian metabolism by the E3 ubiquitin ligase HRD1-controlled CREBH/PPARα transcriptional program. Mol Metab 2021; 49:101192. [PMID: 33592335 PMCID: PMC7966871 DOI: 10.1016/j.molmet.2021.101192] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 02/08/2021] [Accepted: 02/10/2021] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE The endoplasmic reticulum (ER)-resident E3 ligase HRD1 and its co-activator Sel1L are major components of ER-associated degradation (ERAD) machinery. Here, we investigated the molecular mechanism and functional significance underlying the circadian regulation of HRD1/Sel1L-mediated protein degradation program in hepatic energy metabolism. METHODS Genetically engineered animal models as well as gain- and loss-of-function studies were employed to address the circadian regulatory mechanism and functional significance. Gene expression, transcriptional activation, protein-protein interaction, and animal metabolic phenotyping analyses were performed to dissect the molecular network and metabolic pathways. RESULTS Hepatic HRD1 and Sel1L expression exhibits circadian rhythmicity that is controlled by the ER-tethered transcriptional activator CREBH, the nuclear receptor peroxisome proliferator-activated receptor α (PPARα), and the core clock oscillator BMAL1 in mouse livers. HRD1/Sel1L mediates polyubiquitination and degradation of the CREBH protein across the circadian cycle to modulate rhythmic expression of the genes encoding the rate-limiting enzymes or regulators in fatty acid (FA) oxidation, triglyceride (TG) lipolysis, lipophagy, and gluconeogenesis. HRD1 liver-specific knockout (LKO) mice displayed increased expression of the genes involved in lipid and glucose metabolism and impaired circadian profiles of circulating TG, FA, and glucose due to overproduction of CREBH. The circadian metabolic activities of HRD1 LKO mice were inversely correlated with those of CREBH KO mice. Suppressing CREBH overproduction in the livers of HRD1 LKO mice restored the diurnal levels of circulating TG and FA of HRD1 LKO mice. CONCLUSION Our work revealed a key circadian-regulated molecular network through which the E3 ubiquitin ligase HRD1 and its co-activator Sel1L regulate hepatic circadian metabolism.
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Affiliation(s)
- Hyunbae Kim
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Juncheng Wei
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Zhenfeng Song
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Emilio Mottillo
- Hypertension and Vascular Research Division, Henry Ford Hospital, Detroit, MI 48202, USA
| | - Lobelia Samavati
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Ren Zhang
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Li Li
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Xuequn Chen
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Bhanu P Jena
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA; NanoBioScience Institute, Wayne State University, Detroit, MI 48201, USA
| | - Jiandie D Lin
- Life Sciences Institute and Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Deyu Fang
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
| | - Kezhong Zhang
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA; Department of Biochemistry, Microbiology, and Immunology, Wayne State University School of Medicine, Detroit, MI 48201, USA; NanoBioScience Institute, Wayne State University, Detroit, MI 48201, USA.
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63
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Cao T, Peng B, Zhou X, Cai J, Tang Y, Luo J, Xie H, Zhang J, Liu S. Integrated signaling system under endoplasmic reticulum stress in eukaryotic microorganisms. Appl Microbiol Biotechnol 2021; 105:4805-4818. [PMID: 34106312 DOI: 10.1007/s00253-021-11380-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/18/2021] [Accepted: 05/28/2021] [Indexed: 12/11/2022]
Abstract
The endoplasmic reticulum (ER) is a multifunctional organelle, which is crucial for correct folding and assembly of secretory and transmembrane proteins. Perturbations of ER function can cause ER stress. ER stress can activate the unfolded protein response (UPR) to cope with the accumulation of misfolded proteins and protein toxicity. UPR is a coordination system that regulates transcription and translation, leading to the recovery of ER homeostasis or cell death. However, cells have an integrated signaling system to cope with ER stress, which helps cells to restore and balance their ER function. The main components of this system are ER-associated degradation (ERAD), autophagy, hypoxia signaling, and mitochondrial biogenesis. If the balance cannot be restored, the imbalance will lead to cell death or apoptosis, or even to a series of diseases. In this review, a series of activities to restore the homeostasis of cells during ER stress are discussed. KEY POINTS: • Endoplasmic reticulum (ER) plays a key role in the biological process of cells. • Perturbations of ER function can cause ER stress, including the ER overload response (EOR), sterol-regulated cascade reaction, and the UPR. • Cells have an integrated signaling system (ERAD, autophagy, hypoxia signaling, and mitochondrial biogenesis) to cope with the adverse impact caused by ER stress.
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Affiliation(s)
- Ting Cao
- Department of Clinical Laboratory, The First Affiliated Hospital of University of South China, Hengyang, 421000, Hunan, China
| | - Binfeng Peng
- Department of Clinical Laboratory, The First Affiliated Hospital of University of South China, Hengyang, 421000, Hunan, China
| | - Xiangping Zhou
- Department of Clinical Laboratory, The First Affiliated Hospital of University of South China, Hengyang, 421000, Hunan, China
| | - Jialun Cai
- Department of Clinical Laboratory, The First Affiliated Hospital of University of South China, Hengyang, 421000, Hunan, China
| | - Yun Tang
- Department of Clinical Laboratory, The First Affiliated Hospital of University of South China, Hengyang, 421000, Hunan, China
| | - Jie Luo
- Department of Clinical Laboratory, The First Affiliated Hospital of University of South China, Hengyang, 421000, Hunan, China
| | - Haitao Xie
- Department of Clinical Laboratory, The First Affiliated Hospital of University of South China, Hengyang, 421000, Hunan, China
| | - Ji Zhang
- Department of Clinical Laboratory, The First Affiliated Hospital of University of South China, Hengyang, 421000, Hunan, China
| | - Shuangquan Liu
- Department of Clinical Laboratory, The First Affiliated Hospital of University of South China, Hengyang, 421000, Hunan, China.
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64
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Lemberg MK, Strisovsky K. Maintenance of organellar protein homeostasis by ER-associated degradation and related mechanisms. Mol Cell 2021; 81:2507-2519. [PMID: 34107306 DOI: 10.1016/j.molcel.2021.05.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 04/14/2021] [Accepted: 05/05/2021] [Indexed: 12/19/2022]
Abstract
Protein homeostasis mechanisms are fundamentally important to match cellular needs and to counteract stress conditions. A fundamental challenge is to understand how defective proteins are recognized and extracted from cellular organelles to be degraded in the cytoplasm. The endoplasmic reticulum (ER)-associated degradation (ERAD) pathway is the best-understood organellar protein quality control system. Here, we review new insights into the mechanism of recognition and retrotranslocation of client proteins in ERAD. In addition to the membrane-integral ERAD E3 ubiquitin ligases, we highlight one protein family that is remarkably often involved in various aspects of membrane protein quality control and protein dislocation: the rhomboid superfamily, which includes derlins and intramembrane serine proteases. Rhomboid-like proteins have been found to control protein homeostasis in the ER, but also in other eukaryotic organelles and in bacteria, pointing toward conserved principles of membrane protein quality control across organelles and evolution.
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Affiliation(s)
- Marius K Lemberg
- Center for Molecular Biology of Heidelberg University (ZMBH), Im Neuenheimer Feld 282, 69120 Heidelberg, Germany; Center for Biochemistry, Medical Faculty, University of Cologne, Joseph-Stelzmann-Strasse 52, 50931 Cologne, Germany.
| | - Kvido Strisovsky
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czechia.
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65
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Fenech EJ, Ben-Dor S, Schuldiner M. Double the Fun, Double the Trouble: Paralogs and Homologs Functioning in the Endoplasmic Reticulum. Annu Rev Biochem 2021; 89:637-666. [PMID: 32569522 DOI: 10.1146/annurev-biochem-011520-104831] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The evolution of eukaryotic genomes has been propelled by a series of gene duplication events, leading to an expansion in new functions and pathways. While duplicate genes may retain some functional redundancy, it is clear that to survive selection they cannot simply serve as a backup but rather must acquire distinct functions required for cellular processes to work accurately and efficiently. Understanding these differences and characterizing gene-specific functions is complex. Here we explore different gene pairs and families within the context of the endoplasmic reticulum (ER), the main cellular hub of lipid biosynthesis and the entry site for the secretory pathway. Focusing on each of the ER functions, we highlight specificities of related proteins and the capabilities conferred to cells through their conservation. More generally, these examples suggest why related genes have been maintained by evolutionary forces and provide a conceptual framework to experimentally determine why they have survived selection.
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Affiliation(s)
- Emma J Fenech
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel;
| | - Shifra Ben-Dor
- Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel;
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66
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Wu X, Rapoport TA. Translocation of Proteins through a Distorted Lipid Bilayer. Trends Cell Biol 2021; 31:473-484. [PMID: 33531207 PMCID: PMC8122044 DOI: 10.1016/j.tcb.2021.01.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 01/05/2021] [Accepted: 01/07/2021] [Indexed: 12/13/2022]
Abstract
Membranes surrounding cells or organelles represent barriers to proteins and other molecules. However, specific proteins can cross membranes by different translocation systems, the best studied being the Sec61/SecY channel. This channel forms a hydrophilic, hourglass-shaped membrane channel, with a lateral gate towards the surrounding lipid. However, recent studies show that an aqueous pore is not required in other cases of protein translocation. The Hrd1 complex, mediating the retrotranslocation of misfolded proteins from the endoplasmic reticulum (ER) lumen into the cytosol, contains multispanning proteins with aqueous luminal and cytosolic cavities, and lateral gates juxtaposed in a thinned membrane region. A locally thinned, distorted lipid bilayer also allows protein translocation in other systems, suggesting a new paradigm to overcome the membrane barrier.
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Affiliation(s)
- Xudong Wu
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Tom A Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
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67
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Piirainen MA, Frey AD. Investigating the role of ERAD on antibody processing in glycoengineered Saccharomyces cerevisiae. FEMS Yeast Res 2021; 20:5700285. [PMID: 31922547 DOI: 10.1093/femsyr/foaa002] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 01/09/2020] [Indexed: 01/01/2023] Open
Abstract
N-glycosylation plays an important role in the endoplasmic reticulum quality control (ERQC). N-glycan biosynthesis pathways have been engineered in yeasts and fungi to enable the production of therapeutic glycoproteins with human-compatible N-glycosylation, and some glycoengineering approaches alter the synthesis of the lipid-linked oligosaccharide (LLO). Because the effects of LLO engineering on ERQC are currently unknown, we characterized intracellular processing of IgG in glycoengineered Δalg3 Δalg11 Saccharomyces cerevisiae strain and analyzed how altered LLO structures affect endoplasmic reticulum-associated degradation (ERAD). Intracellular IgG light and heavy chain molecules expressed in Δalg3 Δalg11 strain are ERAD substrates and targeted to ERAD independently of Yos9p and Htm1p, whereas in the presence of ALG3 ERAD targeting is dependent on Yos9p but does not require Htm1p. Blocking of ERAD accumulated ER and post-Golgi forms of IgG and increased glycosylation of matα secretion signal but did not improve IgG secretion. Our results show ERAD targeting of a heterologous glycoprotein in yeast, and suggest that proteins in the ER can be targeted to ERAD via other mechanisms than the Htm1p-Yos9p-dependent route when the LLO biosynthesis is altered.
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Affiliation(s)
- Mari A Piirainen
- Department of Bioproducts and Biosystems, Aalto University, Finland, Kemistintie 1, 02150 Espoo, Finland
| | - Alexander D Frey
- Department of Bioproducts and Biosystems, Aalto University, Finland, Kemistintie 1, 02150 Espoo, Finland
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68
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Flagg MP, Wangeline MA, Holland SR, Duttke SH, Benner C, Neal S, Hampton RY. Inner-nuclear-membrane-associated degradation employs Dfm1-independent retrotranslocation and alleviates misfolded transmembrane-protein toxicity. Mol Biol Cell 2021; 32:521-537. [PMID: 33566711 PMCID: PMC8101470 DOI: 10.1091/mbc.e20-11-0720] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 01/27/2021] [Accepted: 02/03/2021] [Indexed: 11/11/2022] Open
Abstract
Before their delivery to and degradation by the 26S proteasome, misfolded transmembrane proteins of the endoplasmic reticulum (ER) and inner-nuclear membrane (INM) must be extracted from lipid bilayers. This extraction process, known as retrotranslocation, requires both quality-control E3 ubiquitin ligases and dislocation factors that diminish the energetic cost of dislodging the transmembrane segments of a protein. Recently, we showed that retrotranslocation of all ER transmembrane proteins requires the Dfm1 rhomboid pseudoprotease. However, we did not investigate whether Dfm1 also mediated retrotranslocation of transmembrane substrates in the INM, which is contiguous with the ER but functionally separated from it by nucleoporins. Here, we show that canonical retrotranslocation occurs during INM-associated degradation (INMAD) but proceeds independently of Dfm1. Despite this independence, ER-associated degradation (ERAD)-M and INMAD cooperate to mitigate proteotoxicity. We show a novel misfolded-transmembrane-protein toxicity that elicits genetic suppression, demonstrating the cell's ability to tolerate a toxic burden of misfolded transmembrane proteins without functional INMAD or ERAD-M. This strikingly contrasted the suppression of the dfm1Δ null, which leads to the resumption of ERAD-M through HRD-complex remodeling. Thus, we conclude that INM retrotranslocation proceeds through a novel, private channel that can be studied by virtue of its role in alleviating membrane-associated proteotoxicity.
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Affiliation(s)
- Matthew P. Flagg
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Margaret A. Wangeline
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Sarah R. Holland
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Sascha H. Duttke
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Christopher Benner
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Sonya Neal
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Randolph Y. Hampton
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
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69
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Molinari M. ER-phagy responses in yeast, plants, and mammalian cells and their crosstalk with UPR and ERAD. Dev Cell 2021; 56:949-966. [PMID: 33765438 DOI: 10.1016/j.devcel.2021.03.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 02/23/2021] [Accepted: 02/27/2021] [Indexed: 12/24/2022]
Abstract
ER-phagy, literally endoplasmic reticulum (ER)-eating, defines the constitutive or regulated clearance of ER portions within metazoan endolysosomes or yeast and plant vacuoles. The advent of electron microscopy led to the first observations of ER-phagy over 60 years ago, but only recently, with the discovery of a set of regulatory proteins named ER-phagy receptors, has it been dissected mechanistically. ER-phagy receptors are activated by a variety of pleiotropic and ER-centric stimuli. They promote ER fragmentation and engage luminal, membrane-bound, and cytosolic factors, eventually driving lysosomal clearance of select ER domains along with their content. After short historical notes, this review introduces the concept of ER-phagy responses (ERPRs). ERPRs ensure lysosomal clearance of ER portions expendable during nutrient shortage, nonfunctional, present in excess, or containing misfolded proteins. They cooperate with unfolded protein responses (UPRs) and with ER-associated degradation (ERAD) in determining ER size, function, and homeostasis.
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Affiliation(s)
- Maurizio Molinari
- Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Institute for Research in Biomedicine, CH-6500 Bellinzona, Switzerland; School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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70
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Rao B, Li S, Yao D, Wang Q, Xia Y, Jia Y, Shen Y, Cao Y. The cryo-EM structure of an ERAD protein channel formed by tetrameric human Derlin-1. SCIENCE ADVANCES 2021; 7:eabe8591. [PMID: 33658201 PMCID: PMC7929502 DOI: 10.1126/sciadv.abe8591] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 01/19/2021] [Indexed: 05/24/2023]
Abstract
Endoplasmic reticulum-associated degradation (ERAD) is a process directing misfolded proteins from the ER lumen and membrane to the degradation machinery in the cytosol. A key step in ERAD is the translocation of ER proteins to the cytosol. Derlins are essential for protein translocation in ERAD, but the mechanism remains unclear. Here, we solved the structure of human Derlin-1 by cryo-electron microscopy. The structure shows that Derlin-1 forms a homotetramer that encircles a large tunnel traversing the ER membrane. The tunnel has a diameter of about 12 to 15 angstroms, large enough to allow an α helix to pass through. The structure also shows a lateral gate within the membrane, providing access of transmembrane proteins to the tunnel, and thus, human Derlin-1 forms a protein channel for translocation of misfolded proteins. Our structure is different from the monomeric yeast Derlin structure previously reported, which forms a semichannel with another protein.
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Affiliation(s)
- Bing Rao
- CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 333 Haike Road, Shanghai 201210, China
| | - Shaobai Li
- Shanghai Institute of Precision of Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
| | - Deqiang Yao
- Shanghai Institute of Precision of Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
| | - Qian Wang
- Shanghai Institute of Precision of Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
| | - Ying Xia
- Shanghai Institute of Precision of Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
| | - Yi Jia
- Shanghai Institute of Precision of Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
| | - Yafeng Shen
- Shanghai Institute of Precision of Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China
| | - Yu Cao
- Shanghai Institute of Precision of Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai 200125, China.
- Department of Orthopaedics, Shanghai Key Laboratory of Orthopaedic Implant, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
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71
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Kang JA, Jeon YJ. How Is the Fidelity of Proteins Ensured in Terms of Both Quality and Quantity at the Endoplasmic Reticulum? Mechanistic Insights into E3 Ubiquitin Ligases. Int J Mol Sci 2021; 22:ijms22042078. [PMID: 33669844 PMCID: PMC7923238 DOI: 10.3390/ijms22042078] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/16/2021] [Accepted: 02/16/2021] [Indexed: 02/06/2023] Open
Abstract
The endoplasmic reticulum (ER) is an interconnected organelle that plays fundamental roles in the biosynthesis, folding, stabilization, maturation, and trafficking of secretory and transmembrane proteins. It is the largest organelle and critically modulates nearly all aspects of life. Therefore, in the endoplasmic reticulum, an enormous investment of resources, including chaperones and protein folding facilitators, is dedicated to adequate protein maturation and delivery to final destinations. Unfortunately, the folding and assembly of proteins can be quite error-prone, which leads to the generation of misfolded proteins. Notably, protein homeostasis, referred to as proteostasis, is constantly exposed to danger by flows of misfolded proteins and subsequent protein aggregates. To maintain proteostasis, the ER triages and eliminates terminally misfolded proteins by delivering substrates to the ubiquitin–proteasome system (UPS) or to the lysosome, which is termed ER-associated degradation (ERAD) or ER-phagy, respectively. ERAD not only eliminates misfolded or unassembled proteins via protein quality control but also fine-tunes correctly folded proteins via protein quantity control. Intriguingly, the diversity and distinctive nature of E3 ubiquitin ligases determine efficiency, complexity, and specificity of ubiquitination during ERAD. ER-phagy utilizes the core autophagy machinery and eliminates ERAD-resistant misfolded proteins. Here, we conceptually outline not only ubiquitination machinery but also catalytic mechanisms of E3 ubiquitin ligases. Further, we discuss the mechanistic insights into E3 ubiquitin ligases involved in the two guardian pathways in the ER, ERAD and ER-phagy. Finally, we provide the molecular mechanisms by which ERAD and ER-phagy conduct not only protein quality control but also protein quantity control to ensure proteostasis and subsequent organismal homeostasis.
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Affiliation(s)
- Ji An Kang
- Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon 35015, Korea;
- Department of Medical Science, College of Medicine, Chungnam National University, Daejeon 35015, Korea
| | - Young Joo Jeon
- Department of Biochemistry, College of Medicine, Chungnam National University, Daejeon 35015, Korea;
- Department of Medical Science, College of Medicine, Chungnam National University, Daejeon 35015, Korea
- Correspondence:
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72
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Hattori T, Hanafusa K, Wada I, Hosokawa N. SEL1L degradation intermediates stimulate cytosolic aggregation of polyglutamine-expanded protein. FEBS J 2021; 288:4637-4654. [PMID: 33576152 DOI: 10.1111/febs.15761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 01/21/2021] [Accepted: 02/05/2021] [Indexed: 12/01/2022]
Abstract
Misfolded proteins in the endoplasmic reticulum (ER) are degraded by ER-associated degradation (ERAD). In mammalian cells, the HRD1-SEL1L membrane ubiquitin ligase complex plays a central role in this process. However, SEL1L is inherently unstable, and excess SEL1L is also degraded by ERAD. Accordingly, when proteasome activity is inhibited, multiple degradation intermediates of SEL1L appear in the cytosol. In this study, we searched for factors that inhibit SEL1L degradation and identified OS-9 and XTP3-B, two ER lectins that regulate glycoprotein ERAD. SEL1L degradation was characterized by a ladder of degradation products, and the C-terminal Pro-rich region of SEL1L was responsible for generation of this pattern. In the cytosol, these degradation intermediates stimulated aggregation of polyglutamine-expanded Huntingtin protein (Htt-polyQ-GFP) by interacting with aggregation-prone proteins, including Htt-polyQ-GFP. Collectively, our findings indicate that peptide fragments of ER proteins generated during ERAD may affect protein aggregation in the cytosol, revealing the interconnection of protein homeostasis across subcellular compartments.
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Affiliation(s)
- Tokuya Hattori
- Department of Molecular and Cellular Biology, Institute for Frontier Medical Sciences, Kyoto University, Japan
| | - Ken Hanafusa
- Department of Molecular and Cellular Biology, Institute for Frontier Medical Sciences, Kyoto University, Japan
| | - Ikuo Wada
- Department of Cell Science, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Japan
| | - Nobuko Hosokawa
- Department of Molecular and Cellular Biology, Institute for Frontier Medical Sciences, Kyoto University, Japan
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73
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Chong WC, Shastri MD, Peterson GM, Patel RP, Pathinayake PS, Dua K, Hansbro NG, Hsu AC, Wark PA, Shukla SD, Johansen MD, Schroder K, Hansbro PM. The complex interplay between endoplasmic reticulum stress and the NLRP3 inflammasome: a potential therapeutic target for inflammatory disorders. Clin Transl Immunology 2021; 10:e1247. [PMID: 33614031 PMCID: PMC7878118 DOI: 10.1002/cti2.1247] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/09/2021] [Accepted: 01/10/2021] [Indexed: 12/15/2022] Open
Abstract
Inflammation is the result of a complex network of cellular and molecular interactions and mechanisms that facilitate immune protection against intrinsic and extrinsic stimuli, particularly pathogens, to maintain homeostasis and promote tissue healing. However, dysregulation in the immune system elicits excess/abnormal inflammation resulting in unintended tissue damage and causes major inflammatory diseases including asthma, chronic obstructive pulmonary disease, atherosclerosis, inflammatory bowel diseases, sarcoidosis and rheumatoid arthritis. It is now widely accepted that both endoplasmic reticulum (ER) stress and inflammasomes play critical roles in activating inflammatory signalling cascades. Notably, evidence is mounting for the involvement of ER stress in exacerbating inflammasome-induced inflammatory cascades, which may provide a new axis for therapeutic targeting in a range of inflammatory disorders. Here, we comprehensively review the roles, mechanisms and interactions of both ER stress and inflammasomes, as well as their interconnected relationships in inflammatory signalling cascades. We also discuss novel therapeutic strategies that are being developed to treat ER stress- and inflammasome-related inflammatory disorders.
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Affiliation(s)
- Wai Chin Chong
- Department of Molecular and Translational ScienceMonash UniversityClaytonVICAustralia
- Centre for Cancer ResearchHudson Institute of Medical ResearchClaytonVICAustralia
| | - Madhur D Shastri
- School of Pharmacy and PharmacologyUniversity of TasmaniaHobartTASAustralia
| | - Gregory M Peterson
- School of Pharmacy and PharmacologyUniversity of TasmaniaHobartTASAustralia
| | - Rahul P Patel
- School of Pharmacy and PharmacologyUniversity of TasmaniaHobartTASAustralia
| | - Prabuddha S Pathinayake
- Priority Research Centre for Healthy LungsHunter Medical Research InstituteThe University of NewcastleCallaghanNSWAustralia
| | - Kamal Dua
- Discipline of PharmacyGraduate School of HealthUniversity of Technology SydneyUltimoNSWAustralia
| | - Nicole G Hansbro
- Centre for InflammationCentenary InstituteFaculty of ScienceSchool of Life SciencesUniversity of TechnologySydneyNSWAustralia
| | - Alan C Hsu
- Priority Research Centre for Healthy LungsHunter Medical Research InstituteThe University of NewcastleCallaghanNSWAustralia
| | - Peter A Wark
- Priority Research Centre for Healthy LungsHunter Medical Research InstituteThe University of NewcastleCallaghanNSWAustralia
| | - Shakti Dhar Shukla
- Priority Research Centre for Healthy LungsHunter Medical Research InstituteThe University of NewcastleCallaghanNSWAustralia
| | - Matt D Johansen
- Centre for InflammationCentenary InstituteFaculty of ScienceSchool of Life SciencesUniversity of TechnologySydneyNSWAustralia
| | - Kate Schroder
- Institute for Molecular BioscienceUniversity of QueenslandSt LuciaQLDAustralia
| | - Philip M Hansbro
- Priority Research Centre for Healthy LungsHunter Medical Research InstituteThe University of NewcastleCallaghanNSWAustralia
- Centre for InflammationCentenary InstituteFaculty of ScienceSchool of Life SciencesUniversity of TechnologySydneyNSWAustralia
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74
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Abstract
The 26S proteasome is the most complex ATP-dependent protease machinery, of ~2.5 MDa mass, ubiquitously found in all eukaryotes. It selectively degrades ubiquitin-conjugated proteins and plays fundamentally indispensable roles in regulating almost all major aspects of cellular activities. To serve as the sole terminal "processor" for myriad ubiquitylation pathways, the proteasome evolved exceptional adaptability in dynamically organizing a large network of proteins, including ubiquitin receptors, shuttle factors, deubiquitinases, AAA-ATPase unfoldases, and ubiquitin ligases, to enable substrate selectivity and processing efficiency and to achieve regulation precision of a vast diversity of substrates. The inner working of the 26S proteasome is among the most sophisticated, enigmatic mechanisms of enzyme machinery in eukaryotic cells. Recent breakthroughs in three-dimensional atomic-level visualization of the 26S proteasome dynamics during polyubiquitylated substrate degradation elucidated an extensively detailed picture of its functional mechanisms, owing to progressive methodological advances associated with cryogenic electron microscopy (cryo-EM). Multiple sites of ubiquitin binding in the proteasome revealed a canonical mode of ubiquitin-dependent substrate engagement. The proteasome conformation in the act of substrate deubiquitylation provided insights into how the deubiquitylating activity of RPN11 is enhanced in the holoenzyme and is coupled to substrate translocation. Intriguingly, three principal modes of coordinated ATP hydrolysis in the heterohexameric AAA-ATPase motor were discovered to regulate intermediate functional steps of the proteasome, including ubiquitin-substrate engagement, deubiquitylation, initiation of substrate translocation and processive substrate degradation. The atomic dissection of the innermost working of the 26S proteasome opens up a new era in our understanding of the ubiquitin-proteasome system and has far-reaching implications in health and disease.
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Affiliation(s)
- Youdong Mao
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, 02215, Massachusetts, USA. .,School of Physics, Center for Quantitative Biology, Peking University, Beijing, 100871, China.
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Devi S, Kim JJ, Singh AP, Kumar S, Dubey AK, Singh SK, Singh RS, Kumar V. Proteotoxicity: A Fatal Consequence of Environmental Pollutants-Induced Impairments in Protein Clearance Machinery. J Pers Med 2021; 11:69. [PMID: 33503824 PMCID: PMC7912547 DOI: 10.3390/jpm11020069] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/20/2021] [Accepted: 01/22/2021] [Indexed: 02/08/2023] Open
Abstract
A tightly regulated protein quality control (PQC) system maintains a healthy balance between correctly folded and misfolded protein species. This PQC system work with the help of a complex network comprised of molecular chaperones and proteostasis. Any intruder, especially environmental pollutants, disrupt the PQC network and lead to PQCs disruption, thus generating damaged and infectious protein. These misfolded/unfolded proteins are linked to several diseases such as Parkinson's disease, Alzheimer's disease, Huntington's disease, and cataracts. Numerous studies on proteins misfolding and disruption of PQCs by environmental pollutants highlight the necessity of detailed knowledge. This review represents the PQCs network and environmental pollutants' impact on the PQC network, especially through the protein clearance system.
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Affiliation(s)
- Shweta Devi
- Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research, Lucknow 226001, India;
| | - Jong-Joo Kim
- Department of Biotechnology, Yeungnam University, Gyeongsan, Gyeongbuk 38541, Korea;
| | - Anand Prakash Singh
- Division of Cardiovascular Disease, The University of Alabama at Birmingham (UAB), 1720 2nd Ave South, Birmingham, AL 35294-1913, USA;
| | - Surendra Kumar
- Cytogenetics Lab, Department of Anatomy, All India Institute of Medical Sciences, New Delhi 110029, India;
| | | | | | - Ravi Shankar Singh
- Department of Biochemistry, Microbiology & Immunology, University of Saskatchewan, Room 4D40, Health Sciences Building, 107 Wiggins Road, Saskatoon, SK S7N 5E5, Canada
| | - Vijay Kumar
- Department of Biotechnology, Yeungnam University, Gyeongsan, Gyeongbuk 38541, Korea;
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Potential Physiological Relevance of ERAD to the Biosynthesis of GPI-Anchored Proteins in Yeast. Int J Mol Sci 2021; 22:ijms22031061. [PMID: 33494405 PMCID: PMC7865462 DOI: 10.3390/ijms22031061] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 12/19/2022] Open
Abstract
Misfolded and/or unassembled secretory and membrane proteins in the endoplasmic reticulum (ER) may be retro-translocated into the cytoplasm, where they undergo ER-associated degradation, or ERAD. The mechanisms by which misfolded proteins are recognized and degraded through this pathway have been studied extensively; however, our understanding of the physiological role of ERAD remains limited. This review describes the biosynthesis and quality control of glycosylphosphatidylinositol (GPI)-anchored proteins and briefly summarizes the relevance of ERAD to these processes. While recent studies suggest that ERAD functions as a fail-safe mechanism for the degradation of misfolded GPI-anchored proteins, several pieces of evidence suggest an intimate interaction between ERAD and the biosynthesis of GPI-anchored proteins.
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Abstract
Folding of proteins is essential so that they can exert their functions. For proteins that transit the secretory pathway, folding occurs in the endoplasmic reticulum (ER) and various chaperone systems assist in acquiring their correct folding/subunit formation. N-glycosylation is one of the most conserved posttranslational modification for proteins, and in eukaryotes it occurs in the ER. Consequently, eukaryotic cells have developed various systems that utilize N-glycans to dictate and assist protein folding, or if they consistently fail to fold properly, to destroy proteins for quality control and the maintenance of homeostasis of proteins in the ER.
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Li K, Zhang K, Wang H, Wu Y, Chen N, Chen J, Qiu C, Cai P, Li M, Liang X, Su D. Hrd1-mediated ACLY ubiquitination alleviate NAFLD in db/db mice. Metabolism 2021; 114:154349. [PMID: 32888949 DOI: 10.1016/j.metabol.2020.154349] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 08/25/2020] [Accepted: 08/27/2020] [Indexed: 12/18/2022]
Abstract
BACKGROUND The functions of Acly in regulating nonalcoholic fatty liver disease (NAFLD) have been identified; however, the dynamic control of Acly expression under the pathological state of metabolic disorders has not been fully elucidated. Previous studies reported an ubiquitin-proteasome-mediated degradation of Acly, but the mechanism is still largely unknown. METHODS Co-IP-based mass spectrum (MS/MS) assays were performed in HepG2 and Hepa1-6 hepatocytes and mouse liver tissue. The protein-protein interaction and ubiquitin modification of Hrd1 on Acly were confirmed by co-IP based immuno-blotting. Acetyl-CoA levels and lipogenesis rates were determined. The roles of Hrd1 on NAFLD and insulin resistance were tested by adenovirus-mediated overexpression in db/db mice or in separated primary hepatocytes. RESULTS Hrd1, a subunit of the endoplasmic reticulum-associated degradation (ERAD) complex, interacted with and ubiquitinated Acly, thereby reducing its protein level. Hrd1 suppressed the acetyl-CoA level and inhibited lipogenesis through an Acly-dependent pathway. The expression of hepatic Hrd1 was negatively associated with NAFLD, whereas overexpression of Hrd1 ameliorated hepatic steatosis and enhanced insulin sensitivity, both in db/db mice and in separated mouse primary hepatocytes. CONCLUSIONS Our results suggest that Acly, a master enzyme that regulates lipogenesis, is degraded by Hrd1 through ubiquitin modification. The activation of Hrd1 in hepatocytes might therefore represent a strategic approach for NAFLD therapy.
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Affiliation(s)
- Kai Li
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing 211166, China
| | - Kaini Zhang
- Department of Pathology, Nanjing Medical University, Nanjing 211166, China
| | - Hai Wang
- Department of Pathology, Nanjing Medical University, Nanjing 211166, China
| | - Yangyang Wu
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing 211166, China
| | - Nuoqi Chen
- Department of Endocrinology, Zhangzhou Municipal Hospital Affiliated to Fujian Medical University, Zhangzhou 363000, China
| | - Jinfeng Chen
- Department of Endocrinology, Zhangzhou Municipal Hospital Affiliated to Fujian Medical University, Zhangzhou 363000, China
| | - Chen Qiu
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing 211166, China; Key Laboratory of the Model Animal Research, Animal Core Facility of Nanjing Medical University, Nanjing 211166, China
| | - Pengpeng Cai
- Department of Gastroenterology, Sir Run Run Hospital, Nanjing Medical University, Nanjing 211166, China
| | - Min Li
- Department of Pathology, Nanjing Medical University, Nanjing 211166, China
| | - Xiubin Liang
- Department of Pathophysiology, Nanjing Medical University, Nanjing 211166, China
| | - Dongming Su
- Department of Pathology, Nanjing Medical University, Nanjing 211166, China; Department of Pathology and Clinical Laboratory, Sir Run Run Hospital of Nanjing Medical University, Nanjing 211166, China.
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Ninagawa S, George G, Mori K. Mechanisms of productive folding and endoplasmic reticulum-associated degradation of glycoproteins and non-glycoproteins. Biochim Biophys Acta Gen Subj 2020; 1865:129812. [PMID: 33316349 DOI: 10.1016/j.bbagen.2020.129812] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 12/09/2020] [Accepted: 12/09/2020] [Indexed: 12/22/2022]
Abstract
BACKGROUND The quality of proteins destined for the secretory pathway is ensured by two distinct mechanisms in the endoplasmic reticulum (ER): productive folding of newly synthesized proteins, which is assisted by ER-localized molecular chaperones and in most cases also by disulfide bond formation and transfer of an oligosaccharide unit; and ER-associated degradation (ERAD), in which proteins unfolded or misfolded in the ER are recognized and processed for delivery to the ER membrane complex, retrotranslocated through the complex with simultaneous ubiquitination, extracted by AAA-ATPase to the cytosol, and finally degraded by the proteasome. SCOPE OF REVIEW We describe the mechanisms of productive folding and ERAD, with particular attention to glycoproteins versus non-glycoproteins, and to yeast versus mammalian systems. MAJOR CONCLUSION Molecular mechanisms of the productive folding of glycoproteins and non-glycoproteins mediated by molecular chaperones and protein disulfide isomerases are well conserved from yeast to mammals. Additionally, mammals have gained an oligosaccharide structure-dependent folding cycle for glycoproteins. The molecular mechanisms of ERAD are also well conserved from yeast to mammals, but redundant expression of yeast orthologues in mammals has been encountered, particularly for components involved in recognition and processing of glycoproteins and components of the ER membrane complex involved in retrotranslocation and simultaneous ubiquitination of glycoproteins and non-glycoproteins. This may reflect an evolutionary consequence of increasing quantity or quality needs toward mammals. GENERAL SIGNIFICANCE The introduction of innovative genome editing technology into analysis of the mechanisms of mammalian ERAD, as exemplified here, will provide new insights into the pathogenesis of various diseases.
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Affiliation(s)
- Satoshi Ninagawa
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
| | - Ginto George
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
| | - Kazutoshi Mori
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
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80
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Liu Y, Tan Z, Yang Y. Negative feedback and modern anti-cancer strategies targeting the ER stress response. FEBS Lett 2020; 594:4247-4265. [PMID: 33206409 DOI: 10.1002/1873-3468.14000] [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: 07/03/2020] [Revised: 09/18/2020] [Accepted: 10/25/2020] [Indexed: 12/13/2022]
Abstract
Endoplasmic reticulum (ER) stress is a cell state in which misfolded or unfolded proteins are aberrantly accumulated in the ER. ER stress induces an evolutionarily conserved adaptive response, named the ER stress response, that deploys a self-regulated machinery to maintain cellular proteostasis. However, compared to its well-established canonical activation mechanism, the negative feedback mechanisms regulating the ER stress response remain unclear and no accepted methods or markers have been established. Several studies have documented that both endogenous and exogenous insults can induce ER stress in cancer. Based on this evidence, small molecule inhibitors targeting ER stress response have been designed to kill cancer cells, with some of them showing excellent curative effects. Here, we review recent advances in our understanding of negative feedback of the ER stress response and compare the markers used to date. We also summarize therapeutic inhibitors targeting ER stress response and highlight the promises and challenges ahead.
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Affiliation(s)
- Yaofu Liu
- Suzhou Institute of Systems Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Suzhou, China
| | - Zhenzhi Tan
- Suzhou Institute of Systems Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Suzhou, China
| | - Yili Yang
- Suzhou Institute of Systems Medicine, Chinese Academy of Medical Sciences & Peking Union Medical College, Suzhou, China
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81
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Wright MT, Kouba L, Plate L. Thyroglobulin Interactome Profiling Defines Altered Proteostasis Topology Associated With Thyroid Dyshormonogenesis. Mol Cell Proteomics 2020; 20:100008. [PMID: 33581410 PMCID: PMC7950113 DOI: 10.1074/mcp.ra120.002168] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 10/15/2020] [Accepted: 11/18/2020] [Indexed: 12/02/2022] Open
Abstract
Thyroglobulin (Tg) is a secreted iodoglycoprotein serving as the precursor for triiodothyronine and thyroxine hormones. Many characterized Tg gene mutations produce secretion-defective variants resulting in congenital hypothyroidism. Tg processing and secretion is controlled by extensive interactions with chaperone, trafficking, and degradation factors comprising the secretory proteostasis network. While dependencies on individual proteostasis network components are known, the integration of proteostasis pathways mediating Tg protein quality control and the molecular basis of mutant Tg misprocessing remain poorly understood. We employ a multiplexed quantitative affinity purification-mass spectrometry approach to define the Tg proteostasis interactome and changes between WT and several congenital hypothyroidism variants. Mutant Tg processing is associated with common imbalances in proteostasis engagement including increased chaperoning, oxidative folding, and engagement by targeting factors for endoplasmic reticulum-associated degradation. Furthermore, we reveal mutation-specific changes in engagement with N-glycosylation components, suggesting distinct requirements for 1 Tg variant on dual engagement of both oligosaccharyltransferase complex isoforms for degradation. Modulating dysregulated proteostasis components and pathways may serve as a therapeutic strategy to restore Tg secretion and thyroid hormone biosynthesis.
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Affiliation(s)
- Madison T Wright
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Logan Kouba
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA; Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA.
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Wright MT, Plate L. Revealing functional insights into ER proteostasis through proteomics and interactomics. Exp Cell Res 2020; 399:112417. [PMID: 33301765 DOI: 10.1016/j.yexcr.2020.112417] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 11/23/2020] [Accepted: 11/28/2020] [Indexed: 12/16/2022]
Abstract
The endoplasmic reticulum (ER), responsible for processing approximately one-third of the human proteome including most secreted and membrane proteins, plays a pivotal role in protein homeostasis (proteostasis). Dysregulation of ER proteostasis has been implicated in a number of disease states. As such, continued efforts are directed at elucidating mechanisms of ER protein quality control which are mediated by transient and dynamic protein-protein interactions with molecular chaperones, co-chaperones, protein folding and trafficking factors that take place in and around the ER. Technological advances in mass spectrometry have played a pivotal role in characterizing and understanding these protein-protein interactions that dictate protein quality control mechanisms. Here, we highlight the recent progress from mass spectrometry-based investigation of ER protein quality control in revealing the topological arrangement of the proteostasis network, stress response mechanisms that adjust the ER proteostasis capacity, and disease specific changes in proteostasis network engagement. We close by providing a brief outlook on underexplored areas of ER proteostasis where mass spectrometry is a tool uniquely primed to further expand our understanding of the regulation and coordination of protein quality control processes in diverse diseases.
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Affiliation(s)
- Madison T Wright
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
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83
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Yan P, Ren J, Zhang W, Qu J, Liu GH. Protein quality control of cell stemness. CELL REGENERATION (LONDON, ENGLAND) 2020; 9:22. [PMID: 33179756 PMCID: PMC7658286 DOI: 10.1186/s13619-020-00064-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 09/14/2020] [Indexed: 02/07/2023]
Abstract
Protein quality control (PQC) systems play essential roles in the recognition, refolding and clearance of aberrant proteins, thus ensuring cellular protein homeostasis, or proteostasis. Especially, continued proliferation and differentiation of stem cells require a high rate of translation; therefore, accurate PQC systems are essential to maintain stem cell function. Growing evidence suggested crucial roles of PQC systems in regulating the stemness and differentiation of stem cells. This review focuses on current knowledge regarding the components of the proteostasis network in stem cells, and the importance of proteostasis in maintaining stem cell identity and regenerative functions. A complete understanding of this process might uncover potential applications in aging intervention and aging-related diseases.
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Affiliation(s)
- Pengze Yan
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jie Ren
- University of Chinese Academy of Sciences, Beijing, 100049, China
- China National Center for Bioinformation, Beijing, 100101, China
- CAS Key Laboratory of Genomic and Precision Medicine, Collaborative Innovation Center of Genetics and Development, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China
- Institute for Stem cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China
| | - Weiqi Zhang
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- China National Center for Bioinformation, Beijing, 100101, China.
- CAS Key Laboratory of Genomic and Precision Medicine, Collaborative Innovation Center of Genetics and Development, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China.
- Institute for Stem cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Jing Qu
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- Institute for Stem cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China.
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Guang-Hui Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- Institute for Stem cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China.
- Beijing Institute for Brain Disorders, Advanced Innovation Center for Human Brain Protection, National Clinical Research Center for Geriatric Disorders, Xuanwu Hospital Capital Medical University, Beijing, 100053, China.
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Christiano R, Arlt H, Kabatnik S, Mejhert N, Lai ZW, Farese RV, Walther TC. A Systematic Protein Turnover Map for Decoding Protein Degradation. Cell Rep 2020; 33:108378. [PMID: 33176155 DOI: 10.1016/j.celrep.2020.108378] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 09/01/2020] [Accepted: 10/21/2020] [Indexed: 01/20/2023] Open
Abstract
Protein degradation is mediated by an expansive and complex network of protein modification and degradation enzymes. Matching degradation enzymes with their targets and determining globally which proteins are degraded by the proteasome or lysosome/vacuole have been a major challenge. Furthermore, an integrated view of protein degradation for cellular pathways has been lacking. Here, we present an analytical platform that combines systematic gene deletions with quantitative measures of protein turnover to deconvolve protein degradation pathways for Saccharomyces cerevisiae. The resulting turnover map (T-MAP) reveals target candidates of nearly all E2 and E3 ubiquitin ligases and identifies the primary degradation routes for most proteins. We further mined this T-MAP to identify new substrates of ER-associated degradation (ERAD) involved in sterol biosynthesis and to uncover regulatory nodes for sphingolipid biosynthesis. The T-MAP approach should be broadly applicable to the study of other cellular processes, including mammalian systems.
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Affiliation(s)
- Romain Christiano
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Henning Arlt
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA
| | - Sonja Kabatnik
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Niklas Mejhert
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Zon Weng Lai
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Harvard T.H. Chan Advanced Multi-Omics Platform, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA
| | - Robert V Farese
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02124, USA.
| | - Tobias C Walther
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02124, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA; Harvard T.H. Chan Advanced Multi-Omics Platform, Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA.
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85
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Park JE, Trần TXT, Park N, Yeom J, Kim K, Kang MJ. The Function of Drosophila USP14 in Endoplasmic Reticulum Stress and Retinal Degeneration in a Model for Autosomal Dominant Retinitis Pigmentosa. BIOLOGY 2020; 9:biology9100332. [PMID: 33053617 PMCID: PMC7650538 DOI: 10.3390/biology9100332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/07/2020] [Accepted: 10/09/2020] [Indexed: 11/29/2022]
Abstract
Simple Summary The present study shows the role of Drosophila USP14 under ER stress and ER stress related disease, autosomal dominant retinitis pigmentosa. Drosophila USP14 protects cell from ER stress triggered by ER stress-causing chemicals Drosophila S2 cells and suppresses the retinal degeneration in disease model for retinitis pigmentosa by regulating the stability of Rhodopsin-1. This study also indicates the dynamic reorganization of proteasome complex under ER stress. The modulation of USP14 could be a potential therapeutic strategy for treating the diseases associated with protein folding. Abstract Endoplasmic reticulum (ER) stress and its adaptive cellular response, the unfolded protein response (UPR), are involved in various diseases including neurodegenerative diseases, metabolic diseases, and even cancers. Here, we analyzed the novel function of ubiquitin-specific peptidase 14 (USP14) in ER stress. The overexpression of Drosophila USP14 protected the cells from ER stress without affecting the proteasomal activity. Null Hong Kong (NHK) and alpha-1-antitrypsin Z (ATZ) are ER-associated degradation substrates. The degradation of NHK, but not of ATZ, was delayed by USP14. USP14 restored the levels of rhodopsin-1 protein in a Drosophila model for autosomal dominant retinitis pigmentosa and suppressed the retinal degeneration in this model. In addition, we observed that proteasome complex is dynamically reorganized in response to ER stress in human 293T cells. These findings suggest that USP14 may be a therapeutic strategy in diseases associated with ER stress.
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Affiliation(s)
- Jung-Eun Park
- Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-E.P.); (T.X.T.T.); (N.P.)
| | - Thị Xuân Thùy Trần
- Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-E.P.); (T.X.T.T.); (N.P.)
| | - Nayoung Park
- Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-E.P.); (T.X.T.T.); (N.P.)
| | - Jeonghun Yeom
- Convergence Medicine Research Center, Asan Institute for Life Sciences, Asan Medical Center, 88-gil, 43 Olympic-ro, Songpa-gu, Seoul 05505, Korea; (J.Y.); (K.K.)
| | - Kyunggon Kim
- Convergence Medicine Research Center, Asan Institute for Life Sciences, Asan Medical Center, 88-gil, 43 Olympic-ro, Songpa-gu, Seoul 05505, Korea; (J.Y.); (K.K.)
| | - Min-Ji Kang
- Department of Biomedical Sciences, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-E.P.); (T.X.T.T.); (N.P.)
- Convergence Medicine Research Center, Asan Institute for Life Sciences, Asan Medical Center, 88-gil, 43 Olympic-ro, Songpa-gu, Seoul 05505, Korea; (J.Y.); (K.K.)
- Correspondence:
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Oommen D, Kizhakkedath P, Jawabri AA, Varghese DS, Ali BR. Proteostasis Regulation in the Endoplasmic Reticulum: An Emerging Theme in the Molecular Pathology and Therapeutic Management of Familial Hypercholesterolemia. Front Genet 2020; 11:570355. [PMID: 33173538 PMCID: PMC7538668 DOI: 10.3389/fgene.2020.570355] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 08/31/2020] [Indexed: 02/05/2023] Open
Abstract
Familial hypercholesterolemia (FH) is an autosomal genetic disease characterized by high serum low-density lipoprotein (LDL) content leading to premature coronary artery disease. The main genetic and molecular causes of FH are mutations in low-density lipoprotein receptor gene (LDLR) resulting in the non-clearance of LDL from the blood by hepatocytes and consequently the formation of plaques. LDLR is synthesized and glycosylated in the endoplasmic reticulum (ER) and then transported to the plasma membrane via Golgi. It is estimated that more than 50% of reported FH-causing mutations in LDLR result in misfolded proteins that are transport-defective and hence retained in ER. ER accumulation of misfolded proteins causes ER-stress and activates unfolded protein response (UPR). UPR aids protein folding, blocks further protein synthesis, and eliminates misfolded proteins via ER-associated degradation (ERAD) to alleviate ER stress. Various studies demonstrated that ER-retained LDLR mutants are subjected to ERAD. Interestingly, chemical chaperones and genetic or pharmacological inhibition of ERAD have been reported to rescue the transport defective mutant LDLR alleles from ERAD and restore their ER-Golgi transport resulting in the expression of functional plasma membrane LDLR. This suggests the possibility of pharmacological modulation of proteostasis in the ER as a therapeutic strategy for FH. In this review, we picture a detailed analysis of UPR and the ERAD processes activated by ER-retained LDLR mutants associated with FH. In addition, we discuss and critically evaluate the potential role of chemical chaperones and ERAD modulators in the therapeutic management of FH.
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Affiliation(s)
- Deepu Oommen
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Praseetha Kizhakkedath
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Aseel A Jawabri
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Divya Saro Varghese
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Bassam R Ali
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates.,Department of Pathology, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates.,Zayed Center for Health Sciences, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
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87
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Escobar-Henriques M, Anton V. Mitochondrial Surveillance by Cdc48/p97: MAD vs. Membrane Fusion. Int J Mol Sci 2020; 21:E6841. [PMID: 32961852 PMCID: PMC7555132 DOI: 10.3390/ijms21186841] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 09/07/2020] [Accepted: 09/08/2020] [Indexed: 11/16/2022] Open
Abstract
Cdc48/p97 is a ring-shaped, ATP-driven hexameric motor, essential for cellular viability. It specifically unfolds and extracts ubiquitylated proteins from membranes or protein complexes, mostly targeting them for proteolytic degradation by the proteasome. Cdc48/p97 is involved in a multitude of cellular processes, reaching from cell cycle regulation to signal transduction, also participating in growth or death decisions. The role of Cdc48/p97 in endoplasmic reticulum-associated degradation (ERAD), where it extracts proteins targeted for degradation from the ER membrane, has been extensively described. Here, we present the roles of Cdc48/p97 in mitochondrial regulation. We discuss mitochondrial quality control surveillance by Cdc48/p97 in mitochondrial-associated degradation (MAD), highlighting the potential pathologic significance thereof. Furthermore, we present the current knowledge of how Cdc48/p97 regulates mitofusin activity in outer membrane fusion and how this may impact on neurodegeneration.
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Affiliation(s)
- Mafalda Escobar-Henriques
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Center for Molecular Medicine Cologne (CMMC), University of Cologne, Joseph-Stelzmann-Straße 26, 50931 Cologne, Germany;
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88
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Larrimore KE, Barattin-Voynova NS, Reid DW, Ng DTW. Aneuploidy-induced proteotoxic stress can be effectively tolerated without dosage compensation, genetic mutations, or stress responses. BMC Biol 2020; 18:117. [PMID: 32900371 PMCID: PMC7487686 DOI: 10.1186/s12915-020-00852-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 08/18/2020] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND The protein homeostasis (proteostasis) network maintains balanced protein synthesis, folding, transport, and degradation within a cell. Failure to maintain proteostasis is associated with aging and disease, leading to concerted efforts to study how the network responds to various proteotoxic stresses. This is often accomplished using ectopic overexpression of well-characterized, model misfolded protein substrates. However, how cells tolerate large-scale, diverse burden to the proteostasis network is not understood. Aneuploidy, the state of imbalanced chromosome content, adversely affects the proteostasis network by dysregulating the expression of hundreds of proteins simultaneously. Using aneuploid haploid yeast cells as a model, we address whether cells can tolerate large-scale, diverse challenges to the proteostasis network. RESULTS Here we characterize several aneuploid Saccharomyces cerevisiae strains isolated from a collection of stable, randomly generated yeast aneuploid cells. These strains exhibit robust growth and resistance to multiple drugs which induce various forms of proteotoxic stress. Whole genome re-sequencing of the strains revealed this was not the result of genetic mutations, and transcriptome profiling combined with ribosome footprinting showed that genes are expressed and translated in accordance to chromosome copy number. In some strains, various facets of the proteostasis network are mildly upregulated without chronic activation of environmental stress response or heat shock response pathways. No severe defects were observed in the degradation of misfolded proteins, using model misfolded substrates of endoplasmic reticulum-associated degradation or cytosolic quality control pathways, and protein biosynthesis capacity was not impaired. CONCLUSIONS We show that yeast strains of some karyotypes in the genetic background studied here can tolerate the large aneuploidy-associated burden to the proteostasis machinery without genetic changes, dosage compensation, or activation of canonical stress response pathways. We suggest that proteotoxic stress, while common, is not always an obligate consequence of aneuploidy, but rather certain karyotypes and genetic backgrounds may be able to tolerate the excess protein burden placed on the protein homeostasis machinery. This may help clarify how cancer cells are paradoxically both highly aneuploid and highly proliferative at the same time.
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Affiliation(s)
- Katherine E Larrimore
- Temasek Life Sciences Laboratory, Singapore, 117604, Singapore.
- Current address: Institute of Medical Biology (IMB), Agency for Science, Technology and Research (A*STAR), Singapore, 138648, Singapore.
| | | | - David W Reid
- Duke-NUS Graduate Medical School, Singapore, 169857, Singapore
- Current address: Moderna Inc., Cambridge, MA, 02139, USA
| | - Davis T W Ng
- Temasek Life Sciences Laboratory, Singapore, 117604, Singapore
- Duke-NUS Graduate Medical School, Singapore, 169857, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore, 117543, Singapore
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89
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Derlin-3 Is Required for Changes in ERAD Complex Formation under ER Stress. Int J Mol Sci 2020; 21:ijms21176146. [PMID: 32858914 PMCID: PMC7504720 DOI: 10.3390/ijms21176146] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 08/18/2020] [Accepted: 08/24/2020] [Indexed: 12/17/2022] Open
Abstract
Endoplasmic reticulum (ER)-associated protein degradation (ERAD) is a quality control system that induces the degradation of ER terminally misfolded proteins. The ERAD system consists of complexes of multiple ER membrane-associated and luminal proteins that function cooperatively. We aimed to reveal the role of Derlin-3 in the ERAD system using the liver, pancreas, and kidney obtained from different mouse genotypes. We performed coimmunoprecipitation and sucrose density gradient centrifugation to unravel the dynamic nature of ERAD complexes. We observed that Derlin-3 is exclusively expressed in the pancreas, and its deficiency leads to the destabilization of Herp and accumulation of ERAD substrates. Under normal conditions, Complex-1a predominantly contains Herp, Derlin-2, HRD1, and SEL1L, and under ER stress, Complex-1b contains Herp, Derlin-3 (instead of Derlin-2), HRD1, and SEL1L. Complex-2 is upregulated under ER stress and contains Derlin-1, Derlin-2, p97, and VIMP. Derlin-3 deficiency suppresses the transition of Derlin-2 from Complex-1a to Complex-2 under ER stress. In the pancreas, Derlin-3 deficiency blocks Derlin-2 transition. In conclusion, the composition of ERAD complexes is tissue-specific and changes in response to ER stress in a Derlin-3-dependent manner. Derlin-3 may play a key role in changing ERAD complex compositions to overcome ER stress.
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90
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Neal S, Syau D, Nejatfard A, Nadeau S, Hampton RY. HRD Complex Self-Remodeling Enables a Novel Route of Membrane Protein Retrotranslocation. iScience 2020; 23:101493. [PMID: 32891886 PMCID: PMC7481253 DOI: 10.1016/j.isci.2020.101493] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/09/2020] [Accepted: 08/19/2020] [Indexed: 12/17/2022] Open
Abstract
ER-associated degradation (ERAD) targets misfolded ER proteins for degradation. Retrotranslocation, a key feature of ERAD, entails removal of ubiquitinated substrates into the cytosol for proteasomal destruction. Recently, it has been shown that the Hrd1 E3 ligase forms a retrotranslocation channel for luminal (ERAD-L) substrates. Conversely, our studies found that integral membrane (ERAD-M) substrates exit the ER through a distinct pathway mediated by the Dfm1 rhomboid protein. Those studies also revealed a second, Hrd1-dependent pathway of ERAD-M retrotranslocation can arise in dfm1Δ null. Here we show that, in the dfm1Δ null, the HRD complex undergoes remodeling to a form that mediates ERAD-M retrotranslocation. Specifically, Hrd1's normally present stochiometric partner Hrd3 is efficiently removed during suppressive remodeling, allowing Hrd1 to function in this novel capacity. Neither Hrd1 autoubiquitination nor its cytosolic domain is required for suppressive ERAD-M retrotranslocation. Thus, the HRD complex displays remarkable functional flexibility in response to ER stress.
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Affiliation(s)
- Sonya Neal
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA.
| | - Della Syau
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Anahita Nejatfard
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Samantha Nadeau
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
| | - Randolph Y Hampton
- Division of Biological Sciences, the Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA
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91
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van de Weijer ML, Krshnan L, Liberatori S, Guerrero EN, Robson-Tull J, Hahn L, Lebbink RJ, Wiertz EJHJ, Fischer R, Ebner D, Carvalho P. Quality Control of ER Membrane Proteins by the RNF185/Membralin Ubiquitin Ligase Complex. Mol Cell 2020; 79:768-781.e7. [PMID: 32738194 PMCID: PMC7482433 DOI: 10.1016/j.molcel.2020.07.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 05/06/2020] [Accepted: 07/07/2020] [Indexed: 12/16/2022]
Abstract
Misfolded proteins in the endoplasmic reticulum (ER) are degraded by ER-associated degradation (ERAD). Although ERAD components involved in degradation of luminal substrates are well characterized, much less is known about quality control of membrane proteins. Here, we analyzed the degradation pathways of two short-lived ER membrane model proteins in mammalian cells. Using a CRISPR-Cas9 genome-wide library screen, we identified an ERAD branch required for quality control of a subset of membrane proteins. Using biochemical and mass spectrometry approaches, we showed that this ERAD branch is defined by an ER membrane complex consisting of the ubiquitin ligase RNF185, the ubiquitin-like domain containing proteins TMUB1/2 and TMEM259/Membralin, a poorly characterized protein. This complex cooperates with cytosolic ubiquitin ligase UBE3C and p97 ATPase in degrading their membrane substrates. Our data reveal that ERAD branches have remarkable specificity for their membrane substrates, suggesting that multiple, perhaps combinatorial, determinants are involved in substrate selection. The RNF185 ubiquitin ligase, Membralin, and TMUB1/2 assemble into an ERAD complex RNF185/Membralin complex targets membrane proteins, including CYP51A1 and TMUB2 RNF185/Membralin and TEB4 ERAD complexes recognize distinct substrate features TEB4 ERAD complex recognizes substrates through their transmembrane domain
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Affiliation(s)
- Michael L van de Weijer
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Logesvaran Krshnan
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Sabrina Liberatori
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Elena Navarro Guerrero
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford OX3 7FZ, UK
| | - Jacob Robson-Tull
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Lilli Hahn
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Robert Jan Lebbink
- Medical Microbiology, University Medical Center Utrecht, 3584 Utrecht, the Netherlands
| | - Emmanuel J H J Wiertz
- Medical Microbiology, University Medical Center Utrecht, 3584 Utrecht, the Netherlands
| | - Roman Fischer
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford OX3 7FZ, UK
| | - Daniel Ebner
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford OX3 7FZ, UK
| | - Pedro Carvalho
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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92
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Lopata A, Kniss A, Löhr F, Rogov VV, Dötsch V. Ubiquitination in the ERAD Process. Int J Mol Sci 2020; 21:ijms21155369. [PMID: 32731622 PMCID: PMC7432864 DOI: 10.3390/ijms21155369] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/23/2020] [Accepted: 07/27/2020] [Indexed: 01/08/2023] Open
Abstract
In this review, we focus on the ubiquitination process within the endoplasmic reticulum associated protein degradation (ERAD) pathway. Approximately one third of all synthesized proteins in a cell are channeled into the endoplasmic reticulum (ER) lumen or are incorporated into the ER membrane. Since all newly synthesized proteins enter the ER in an unfolded manner, folding must occur within the ER lumen or co-translationally, rendering misfolding events a serious threat. To prevent the accumulation of misfolded protein in the ER, proteins that fail the quality control undergo retrotranslocation into the cytosol where they proceed with ubiquitination and degradation. The wide variety of misfolded targets requires on the one hand a promiscuity of the ubiquitination process and on the other hand a fast and highly processive mechanism. We present the various ERAD components involved in the ubiquitination process including the different E2 conjugating enzymes, E3 ligases, and E4 factors. The resulting K48-linked and K11-linked ubiquitin chains do not only represent a signal for degradation by the proteasome but are also recognized by the AAA+ ATPase Cdc48 and get in the process of retrotranslocation modified by enzymes bound to Cdc48. Lastly we discuss the conformations adopted in particular by K48-linked ubiquitin chains and their importance for degradation.
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93
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He Y, Khan S, Huo Z, Lv D, Zhang X, Liu X, Yuan Y, Hromas R, Xu M, Zheng G, Zhou D. Proteolysis targeting chimeras (PROTACs) are emerging therapeutics for hematologic malignancies. J Hematol Oncol 2020; 13:103. [PMID: 32718354 PMCID: PMC7384229 DOI: 10.1186/s13045-020-00924-z] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 06/23/2020] [Indexed: 12/11/2022] Open
Abstract
Proteolysis targeting chimeras (PROTACs) are heterobifunctional small molecules that utilize the ubiquitin proteasome system (UPS) to degrade proteins of interest (POI). PROTACs are potentially superior to conventional small molecule inhibitors (SMIs) because of their unique mechanism of action (MOA, i.e., degrading POI in a sub-stoichiometric manner), ability to target “undruggable” and mutant proteins, and improved target selectivity. Therefore, PROTACs have become an emerging technology for the development of novel targeted anticancer therapeutics. In fact, some of these reported PROTACs exhibit unprecedented efficacy and specificity in degrading various oncogenic proteins and have advanced to various stages of preclinical and clinical development for the treatment of cancer and hematologic malignancy. In this review, we systematically summarize the known PROTACs that have the potential to be used to treat various hematologic malignancies and discuss strategies to improve the safety of PROTACs for clinical application. Particularly, we propose to use the latest human pan-tissue single-cell RNA sequencing data to identify hematopoietic cell type-specific/selective E3 ligases to generate tumor-specific/selective PROTACs. These PROTACs have the potential to become safer therapeutics for hematologic malignancies because they can overcome some of the on-target toxicities of SMIs and PROTACs.
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Affiliation(s)
- Yonghan He
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, USA
| | - Sajid Khan
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, USA
| | - Zhiguang Huo
- Department of Biostatistics, College of Public Health & Health Professions and College of Medicine, University of Florida, Gainesville, FL, USA
| | - Dongwen Lv
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, USA
| | - Xuan Zhang
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL, USA
| | - Xingui Liu
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, USA
| | - Yaxia Yuan
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, USA
| | - Robert Hromas
- Department of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Mingjiang Xu
- Department of Molecular Medicine, College of Medicine, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Guangrong Zheng
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL, USA
| | - Daohong Zhou
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, Gainesville, FL, USA.
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94
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Qin X, Denton WD, Huiting LN, Smith KS, Feng H. Unraveling the regulatory role of endoplasmic-reticulum-associated degradation in tumor immunity. Crit Rev Biochem Mol Biol 2020; 55:322-353. [PMID: 32633575 DOI: 10.1080/10409238.2020.1784085] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
During malignant transformation and cancer progression, tumor cells face both intrinsic and extrinsic stress, endoplasmic reticulum (ER) stress in particular. To survive and proliferate, tumor cells use multiple stress response pathways to mitigate ER stress, promoting disease aggression and treatment resistance. Among the stress response pathways is ER-associated degradation (ERAD), which consists of multiple components and steps working together to ensure protein quality and quantity. In addition to its established role in stress responses and tumor cell survival, ERAD has recently been shown to regulate tumor immunity. Here we summarize current knowledge on how ERAD promotes protein degradation, regulates immune cell development and function, participates in antigen presentation, exerts paradoxical roles on tumorigenesis and immunity, and thus impacts current cancer therapy. Collectively, ERAD is a critical protein homeostasis pathway intertwined with cancer development and tumor immunity. Of particular importance is the need to further unveil ERAD's enigmatic roles in tumor immunity to develop effective targeted and combination therapy for successful treatment of cancer.
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Affiliation(s)
- Xiaodan Qin
- Departments of Pharmacology and Medicine, Section of Hematology and Medical Oncology, Center for Cancer Research, Boston University School of Medicine, Boston, MA, USA
| | - William D Denton
- Departments of Pharmacology and Medicine, Section of Hematology and Medical Oncology, Center for Cancer Research, Boston University School of Medicine, Boston, MA, USA
| | - Leah N Huiting
- Departments of Pharmacology and Medicine, Section of Hematology and Medical Oncology, Center for Cancer Research, Boston University School of Medicine, Boston, MA, USA
| | - Kaylee S Smith
- Departments of Pharmacology and Medicine, Section of Hematology and Medical Oncology, Center for Cancer Research, Boston University School of Medicine, Boston, MA, USA
| | - Hui Feng
- Departments of Pharmacology and Medicine, Section of Hematology and Medical Oncology, Center for Cancer Research, Boston University School of Medicine, Boston, MA, USA
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95
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Fenech EJ, Lari F, Charles PD, Fischer R, Laétitia-Thézénas M, Bagola K, Paton AW, Paton JC, Gyrd-Hansen M, Kessler BM, Christianson JC. Interaction mapping of endoplasmic reticulum ubiquitin ligases identifies modulators of innate immune signalling. eLife 2020; 9:e57306. [PMID: 32614325 PMCID: PMC7332293 DOI: 10.7554/elife.57306] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/11/2020] [Indexed: 12/25/2022] Open
Abstract
Ubiquitin ligases (E3s) embedded in the endoplasmic reticulum (ER) membrane regulate essential cellular activities including protein quality control, calcium flux, and sterol homeostasis. At least 25 different, transmembrane domain (TMD)-containing E3s are predicted to be ER-localised, but for most their organisation and cellular roles remain poorly defined. Using a comparative proteomic workflow, we mapped over 450 protein-protein interactions for 21 stably expressed, full-length E3s. Bioinformatic analysis linked ER-E3s and their interactors to multiple homeostatic, regulatory, and metabolic pathways. Among these were four membrane-embedded interactors of RNF26, a polytopic E3 whose abundance is auto-regulated by ubiquitin-proteasome dependent degradation. RNF26 co-assembles with TMEM43, ENDOD1, TMEM33 and TMED1 to form a complex capable of modulating innate immune signalling through the cGAS-STING pathway. This RNF26 complex represents a new modulatory axis of STING and innate immune signalling at the ER membrane. Collectively, these data reveal the broad scope of regulation and differential functionalities mediated by ER-E3s for both membrane-tethered and cytoplasmic processes.
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Affiliation(s)
- Emma J Fenech
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Federica Lari
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Philip D Charles
- TDI Mass Spectrometry Laboratory, Target Discovery Institute, University of OxfordOxfordUnited Kingdom
| | - Roman Fischer
- TDI Mass Spectrometry Laboratory, Target Discovery Institute, University of OxfordOxfordUnited Kingdom
| | - Marie Laétitia-Thézénas
- TDI Mass Spectrometry Laboratory, Target Discovery Institute, University of OxfordOxfordUnited Kingdom
| | - Katrin Bagola
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Adrienne W Paton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of AdelaideAdelaideAustralia
| | - James C Paton
- Research Centre for Infectious Diseases, Department of Molecular and Biomedical Science, University of AdelaideAdelaideAustralia
| | - Mads Gyrd-Hansen
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Benedikt M Kessler
- TDI Mass Spectrometry Laboratory, Target Discovery Institute, University of OxfordOxfordUnited Kingdom
- Chinese Academy of Medical Sciences Oxford Institute, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - John C Christianson
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
- Nuffield Department of Orthopaedics, Rheumatology, and Musculoskeletal Sciences, University of Oxford, Botnar Research CentreOxfordUnited Kingdom
- Oxford Centre for Translational Myeloma Research, University of Oxford, Botnar Research CentreOxfordUnited Kingdom
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96
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Rajakumar S, Vijayakumar R, Abhishek A, Selvam GS, Nachiappan V. Loss of ERAD bridging factor UBX2 modulates lipid metabolism and leads to ER stress-associated apoptosis during cadmium toxicity in Saccharomyces cerevisiae. Curr Genet 2020; 66:1003-1017. [DOI: 10.1007/s00294-020-01090-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 06/08/2020] [Accepted: 06/22/2020] [Indexed: 12/17/2022]
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97
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Chua NK, Coates HW, Brown AJ. Squalene monooxygenase: a journey to the heart of cholesterol synthesis. Prog Lipid Res 2020; 79:101033. [DOI: 10.1016/j.plipres.2020.101033] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/21/2020] [Accepted: 04/24/2020] [Indexed: 02/07/2023]
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98
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Sruthi P, Puthur JT. High NaCl tolerance potential of Bruguiera cylindrica (L.) Blume compromised by mild CuSO 4 concentration as evidenced by unique physiochemical features. MARINE POLLUTION BULLETIN 2020; 156:111260. [PMID: 32510402 DOI: 10.1016/j.marpolbul.2020.111260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 04/29/2020] [Accepted: 05/08/2020] [Indexed: 06/11/2023]
Abstract
Differential response of Bruguiera cylindrica to individual (CuSO4) and combined (CuSO4 NaCl) effect was evaluated. The plantlets were treated with control, 0.15 mM CuSO4, 400 mM NaCl and 0.15 mM CuSO4 + 400 mM NaCl. Under combined stress, higher accumulation of Cu in the roots indicate that the roots are the primary site of Cu accumulation and thus the plant perform as an excluder and photosynthetic efficiency reduced drastically and significant enhancement in the superoxide and hydroxyl free radicals which increase membrane lipid peroxidation, leading to cellular damage and destruction. As evidenced from SEM-EDXMA, increase in Cu and Na+ levels in xylem and pith regions of leaf and stem and the presence of deeply stained structures, denoting the probable formation of complex containing the metal. Increased CaOx crystal forming cells (crystal idioblasts) reveals the regulation of bioaccumulated Cu and Na+ by complexing with CaOx. Thus the study suggested that, 400 mM NaCl and 0.15 mM CuSO4 treatments does not have negative impact on plant growth, the NaCl tolerance potential compromised in the presence of mild CuSO4 concentration during combined stress.
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Affiliation(s)
- Palliyath Sruthi
- Plant Physiology and Biochemistry Division, Department of Botany, University of Calicut, C.U. Campus P.O., Kerala 673635, India
| | - Jos T Puthur
- Plant Physiology and Biochemistry Division, Department of Botany, University of Calicut, C.U. Campus P.O., Kerala 673635, India.
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ER-localized Hrd1 ubiquitinates and inactivates Usp15 to promote TLR4-induced inflammation during bacterial infection. Nat Microbiol 2020; 4:2331-2346. [PMID: 31477895 DOI: 10.1038/s41564-019-0542-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The special organelle-located MAVS, STING and TLR3 are important for clearing viral infections. Although TLR4 triggers NF-κB activation to produce pro-inflammatory cytokines for bacterial clearance, effectors with special organelle localization have not been identified. Here, we screened more than 280 E3 ubiquitin ligases and discovered that the endoplasmic reticulum-located Hrd1 regulates TLR4-induced inflammation during bacterial infection. Hrd1 interacts directly with the deubiquitinating enzyme Usp15. Unlike the classical function of Hrd1 in endoplasmic reticulum-associated degradation, Usp15 is not degraded but loses its deubiquitinating activity for IκBα deubiquitination, resulting in excessive NF-κB activation. Importantly, Hrd1 deficiency in macrophages protects mice against lipopolysaccharide-induced septic shock, and knockdown of Usp15 in Hrd1-knockout macrophages restores the reduced IL-6 production. This study proposes that there is crosstalk between Hrd1 and TLR4, thereby linking the endoplasmic reticulum-plasma membrane function during bacterial infection.
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Hosomi A, Iida K, Cho T, Iida H, Kaneko M, Suzuki T. The ER-associated protease Ste24 prevents N-terminal signal peptide-independent translocation into the endoplasmic reticulum in Saccharomyces cerevisiae. J Biol Chem 2020; 295:10406-10419. [PMID: 32513868 DOI: 10.1074/jbc.ra120.012575] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 06/03/2020] [Indexed: 12/14/2022] Open
Abstract
Soluble proteins destined for the secretory pathway contain an N-terminal signal peptide that induces their translocation into the endoplasmic reticulum (ER). The importance of N-terminal signal peptides for ER translocation has been extensively examined over the past few decades. However, in the budding yeast Saccharomyces cerevisiae, a few proteins devoid of a signal peptide are still translocated into the ER and then N-glycosyl-ated. Using signal peptide-truncated reporter proteins, here we report the detection of significant translocation of N-terminal signal peptide-truncated proteins in a yeast mutant strain (ste24Δ) that lacks the endopeptidase Ste24 at the ER membrane. Furthermore, several ER/cytosolic proteins, including Sec61, Sec66, and Sec72, were identified as being involved in the translocation process. On the basis of screening for 20 soluble proteins that may be N-glycosylated in the ER in the ste24Δ strain, we identified the transcription factor Rme1 as a protein that is partially N-glycosylated despite the lack of a signal peptide. These results clearly indicate that some proteins lacking a signal peptide can be translocated into the ER and that Ste24 typically suppresses this process.
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Affiliation(s)
- Akira Hosomi
- Department of Agriculture, Graduate School of Science and Technology, Shinshu University, Kamiina, Nagano, Japan
| | - Kazuko Iida
- Laboratory of Biomembrane, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo, Japan
| | - Toshihiko Cho
- Department of Biology, Tokyo Gakugei University, Koganei, Tokyo, Japan
| | - Hidetoshi Iida
- Department of Biology, Tokyo Gakugei University, Koganei, Tokyo, Japan
| | - Masashi Kaneko
- Department of Agriculture, Graduate School of Science and Technology, Shinshu University, Kamiina, Nagano, Japan
| | - Tadashi Suzuki
- Glycometabolic Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, Wako, Saitama, Japan
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