1
|
Chen S, Collart MA. Membrane-associated mRNAs: A Post-transcriptional Pathway for Fine-turning Gene Expression. J Mol Biol 2024; 436:168579. [PMID: 38648968 DOI: 10.1016/j.jmb.2024.168579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 04/14/2024] [Accepted: 04/16/2024] [Indexed: 04/25/2024]
Abstract
Gene expression is a fundamental and highly regulated process involving a series of tightly coordinated steps, including transcription, post-transcriptional processing, translation, and post-translational modifications. A growing number of studies have revealed an additional layer of complexity in gene expression through the phenomenon of mRNA subcellular localization. mRNAs can be organized into membraneless subcellular structures within both the cytoplasm and the nucleus, but they can also targeted to membranes. In this review, we will summarize in particular our knowledge on localization of mRNAs to organelles, focusing on important regulators and available techniques for studying organellar localization, and significance of this localization in the broader context of gene expression regulation.
Collapse
Affiliation(s)
- Siyu Chen
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Institute of Genetics and Genomics of Geneva, Geneva, Switzerland.
| | - Martine A Collart
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Institute of Genetics and Genomics of Geneva, Geneva, Switzerland.
| |
Collapse
|
2
|
Komatsu M, Inada T, Noda NN. The UFM1 system: Working principles, cellular functions, and pathophysiology. Mol Cell 2024; 84:156-169. [PMID: 38141606 DOI: 10.1016/j.molcel.2023.11.034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 10/21/2023] [Accepted: 11/27/2023] [Indexed: 12/25/2023]
Abstract
Ubiquitin-fold modifier 1 (UFM1) is a ubiquitin-like protein covalently conjugated with intracellular proteins through UFMylation, a process similar to ubiquitylation. Growing lines of evidence regarding not only the structural basis of the components essential for UFMylation but also their biological properties shed light on crucial roles of the UFM1 system in the endoplasmic reticulum (ER), such as ER-phagy and ribosome-associated quality control at the ER, although there are some functions unrelated to the ER. Mouse genetics studies also revealed the indispensable roles of this system in hematopoiesis, liver development, neurogenesis, and chondrogenesis. Of critical importance, mutations of genes encoding core components of the UFM1 system in humans cause hereditary developmental epileptic encephalopathy and Schohat-type osteochondrodysplasia of the epiphysis. Here, we provide a multidisciplinary review of our current understanding of the mechanisms and cellular functions of the UFM1 system as well as its pathophysiological roles, and discuss issues that require resolution.
Collapse
Affiliation(s)
- Masaaki Komatsu
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan.
| | - Toshifumi Inada
- Division of RNA and gene regulation, Institute of Medical Science, The University of Tokyo, Minato-Ku, Tokyo 108-8639, Japan.
| | - Nobuo N Noda
- Institute for Genetic Medicine, Hokkaido University, Kita-Ku, Sapporo 060-0815, Japan; Institute of Microbial Chemistry (Bikaken), Shinagawa-ku, Tokyo 141-0021, Japan.
| |
Collapse
|
3
|
Li X, Mariappan M. Nascent Chain Ubiquitination is Uncoupled from Degradation to Enable Protein Maturation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.09.561585. [PMID: 37873109 PMCID: PMC10592752 DOI: 10.1101/2023.10.09.561585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
A significant proportion of nascent proteins undergo polyubiquitination on ribosomes in mammalian cells, yet the fate of these proteins remains elusive. The ribosome-associated quality control (RQC) is a mechanism that mediates the ubiquitination of nascent chains on stalled ribosomes. Here, we find that nascent proteins ubiquitinated on stalled ribosomes by the RQC E3 ligase LTN1 are insufficient for proteasomal degradation. Our biochemical reconstitution studies reveal that ubiquitinated nascent chains are promptly deubiquitinated in the cytosol upon release from stalled ribosomes, as they are no longer associated with LTN1 E3 ligase for continuous ubiquitination to compete with cytosolic deubiquitinases. These deubiquitinated nascent chains can mature into stable proteins. However, if they misfold and expose a degradation signal, the cytosolic quality control recognizes them for re-ubiquitination and subsequent proteasomal degradation. Thus, our findings suggest that cycles of ubiquitination and deubiquitination spare foldable nascent proteins while ensuring the degradation of terminally misfolded proteins.
Collapse
Affiliation(s)
- Xia Li
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, Yale University West Campus, West Haven, CT 06516, USA
| | - Malaiyalam Mariappan
- Department of Cell Biology, Nanobiology Institute, Yale School of Medicine, Yale University West Campus, West Haven, CT 06516, USA
| |
Collapse
|
4
|
Sogawa A, Komori R, Yanagitani K, Ohfurudono M, Tsuru A, Kadoi K, Kimata Y, Yoshida H, Kohno K. Signal sequence-triage is activated by translocon obstruction sensed by an ER stress sensor IRE1α. Cell Struct Funct 2023; 48:211-221. [PMID: 37766570 DOI: 10.1247/csf.23072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023] Open
Abstract
Secretory pathway proteins are cotranslationally translocated into the endoplasmic reticulum (ER) of metazoan cells through the protein channel, translocon. Given that there are far fewer translocons than ribosomes in a cell, it is essential that secretory protein-translating ribosomes only occupy translocons transiently. Therefore, if translocons are obstructed by ribosomes stalled or slowed in translational elongation, it possibly results in deleterious consequences to cellular function. Hence, we investigated how translocon clogging by stalled ribosomes affects mammalian cells. First, we constructed ER-destined translational arrest proteins (ER-TAP) as an artificial protein that clogged the translocon in the ER membrane. Here, we show that the translocon clogging by ER-TAP expression activates triage of signal sequences (SS) in which secretory pathway proteins harboring highly efficient SS are preferentially translocated into the ER lumen. Interestingly, the translocon obstructed status specifically activates inositol requiring enzyme 1α (IRE1α) but not protein kinase R-like ER kinase (PERK). Given that the IRE1α-XBP1 pathway mainly induces the translocon components, our discovery implies that lowered availability of translocon activates IRE1α, which induces translocon itself. This results in rebalance between protein influx into the ER and the cellular translocation capacity.Key words: endoplasmic reticulum, translocation capacity, translocon clogging, IRE1, signal sequence.
Collapse
Affiliation(s)
- Ashuei Sogawa
- Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST)
- Osaka International Cancer Institute (OICI)
| | - Ryota Komori
- Institute for Research Initiatives, Nara Institute of Science and Technology (NAIST)
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology (NAIST)
- Department of Biochemistry and Molecular Biology, Graduate School of Science, University of Hyogo
| | - Kota Yanagitani
- Institute for Research Initiatives, Nara Institute of Science and Technology (NAIST)
- Ubiquitin Biology Laboratory, Graduate School of Frontier Biosciences, Osaka University
| | - Miku Ohfurudono
- Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST)
- Institute for Research Initiatives, Nara Institute of Science and Technology (NAIST)
| | - Akio Tsuru
- Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST)
- Institute for Research Initiatives, Nara Institute of Science and Technology (NAIST)
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology (NAIST)
| | - Koji Kadoi
- Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST)
| | - Yukio Kimata
- Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST)
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology (NAIST)
| | - Hiderou Yoshida
- Department of Biochemistry and Molecular Biology, Graduate School of Science, University of Hyogo
| | - Kenji Kohno
- Laboratory of Molecular and Cell Genetics, Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST)
- Institute for Research Initiatives, Nara Institute of Science and Technology (NAIST)
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology (NAIST)
- Department of Biochemistry and Molecular Biology, Graduate School of Science, University of Hyogo
| |
Collapse
|
5
|
Meydan S, Guydosh NR. Is there a localized role for translational quality control? RNA (NEW YORK, N.Y.) 2023; 29:1623-1643. [PMID: 37582617 PMCID: PMC10578494 DOI: 10.1261/rna.079683.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 07/26/2023] [Indexed: 08/17/2023]
Abstract
It is known that mRNAs and the machinery that translates them are not uniformly distributed throughout the cytoplasm. As a result, the expression of some genes is localized to particular parts of the cell and this makes it possible to carry out important activities, such as growth and signaling, in three-dimensional space. However, the functions of localized gene expression are not fully understood, and the underlying mechanisms that enable localized expression have not been determined in many cases. One consideration that could help in addressing these challenges is the role of quality control (QC) mechanisms that monitor translating ribosomes. On a global level, QC pathways are critical for detecting aberrant translation events, such as a ribosome that stalls while translating, and responding by activating stress pathways and resolving problematic ribosomes and mRNAs at the molecular level. However, it is unclear how these pathways, even when uniformly active throughout the cell, affect local translation. Importantly, some QC pathways have themselves been reported to be enriched in the proximity of particular organelles, but the extent of such localized activity remains largely unknown. Here, we describe the major QC pathways and review studies that have begun to explore their roles in localized translation. Given the limited data in this area, we also pose broad questions about the possibilities and limitations for how QC pathways could facilitate localized gene expression in the cell with the goal of offering ideas for future experimentation.
Collapse
Affiliation(s)
- Sezen Meydan
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
- National Institute of General Medical Sciences, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Nicholas R Guydosh
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| |
Collapse
|
6
|
Ishimura R, Ito S, Mao G, Komatsu-Hirota S, Inada T, Noda NN, Komatsu M. Mechanistic insights into the roles of the UFM1 E3 ligase complex in ufmylation and ribosome-associated protein quality control. SCIENCE ADVANCES 2023; 9:eadh3635. [PMID: 37595036 PMCID: PMC10438457 DOI: 10.1126/sciadv.adh3635] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 07/18/2023] [Indexed: 08/20/2023]
Abstract
Ubiquitin-fold modifier 1 (UFM1) is a ubiquitin-like protein covalently conjugated with intracellular proteins through ufmylation, similar to ubiquitylation. Ufmylation is involved in processes such as endoplasmic reticulum (ER)-associated protein degradation, ribosome-associated protein quality control (RQC) at the ER (ER-RQC), and ER-phagy. However, it remains unclear how ufmylation regulates such distinct ER-related functions. Here, we provide insights into the mechanism of the UFM1 E3 complex in not only ufmylation but also ER-RQC. The E3 complex consisting of UFL1 and UFBP1 interacted with UFC1, UFM1 E2, and, subsequently, CDK5RAP3, an adaptor for ufmylation of ribosomal subunit RPL26. Upon disome formation, the E3 complex associated with ufmylated RPL26 on the 60S subunit through the UFM1-interacting region of UFBP1. Loss of E3 components or disruption of the interaction between UFBP1 and ufmylated RPL26 attenuated ER-RQC. These results provide insights into not only the molecular basis of the ufmylation but also its role in proteostasis.
Collapse
Affiliation(s)
- Ryosuke Ishimura
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Sota Ito
- Division of RNA and Gene Regulation, Institute of Medical Science, The University of Tokyo, Minato-Ku 108-8639, Japan
| | - Gaoxin Mao
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Satoko Komatsu-Hirota
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Toshifumi Inada
- Division of RNA and Gene Regulation, Institute of Medical Science, The University of Tokyo, Minato-Ku 108-8639, Japan
| | - Nobuo N. Noda
- Institute for Genetic Medicine, Hokkaido University, Kita-Ku, Sapporo 060-0815, Japan
- Institute of Microbial Chemistry (Bikaken), Shinagawa-ku, Tokyo 141-0021, Japan
| | - Masaaki Komatsu
- Department of Physiology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan
| |
Collapse
|
7
|
Scavone F, Gumbin S, Da Rosa P, Kopito R. RPL26/uL24 UFMylation is essential for ribosome-associated quality control at the endoplasmic reticulum. Proc Natl Acad Sci U S A 2023; 120:e2220340120. [PMID: 37036982 PMCID: PMC10120006 DOI: 10.1073/pnas.2220340120] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 03/14/2023] [Indexed: 04/12/2023] Open
Abstract
Ribosomes that stall while translating cytosolic proteins are incapacitated by incomplete nascent chains, termed "arrest peptides" (APs) that are destroyed by the ubiquitin proteasome system (UPS) via a process known as the ribosome-associated quality control (RQC) pathway. By contrast, APs on ribosomes that stall while translocating secretory proteins into the endoplasmic reticulum (ER-APs) are shielded from cytosol by the ER membrane and the tightly sealed ribosome-translocon junction (RTJ). How this junction is breached to enable access of cytosolic UPS machinery and 26S proteasomes to translocon- and ribosome-obstructing ER-APs is not known. Here, we show that UPS and RQC-dependent degradation of ER-APs strictly requires conjugation of the ubiquitin-like (Ubl) protein UFM1 to 60S ribosomal subunits at the RTJ. Therefore, UFMylation of translocon-bound 60S subunits modulates the RTJ to promote access of proteasomes and RQC machinery to ER-APs.
Collapse
Affiliation(s)
| | - Samantha C. Gumbin
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA94305
| | - Paul A. Da Rosa
- Department of Biology, Stanford University, Stanford, CA94305
| | - Ron R. Kopito
- Department of Biology, Stanford University, Stanford, CA94305
| |
Collapse
|
8
|
Scavone F, Gumbin SC, DaRosa PA, Kopito RR. RPL26/uL24 UFMylation is essential for ribosome-associated quality control at the endoplasmic reticulum. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.08.531792. [PMID: 36945571 PMCID: PMC10028864 DOI: 10.1101/2023.03.08.531792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Ribosomes that stall while translating cytosolic proteins are incapacitated by incomplete nascent chains, termed "arrest peptides" (APs) that are destroyed by the ubiquitin proteasome system (UPS) via a process known as the ribosome-associated quality control (RQC) pathway. By contrast, APs on ribosomes that stall while translocating secretory proteins into the endoplasmic reticulum (ER-APs) are shielded from cytosol by the ER membrane and the tightly sealed ribosome-translocon junction (RTJ). How this junction is breached to enable access of cytosolic UPS machinery and 26S proteasomes to translocon- and ribosome-obstructing ER-APs is not known. Here, we show that UPS and RQC-dependent degradation of ER-APs strictly requires conjugation of the ubiquitin-like (Ubl) protein UFM1 to 60S ribosomal subunits at the RTJ. Therefore, UFMylation of translocon-bound 60S subunits modulates the RTJ to promote access of proteasomes and RQC machinery to ER-APs. Significance Statement UFM1 is a ubiquitin-like protein that is selectively conjugated to the large (60S) subunit of ribosomes bound to the endoplasmic reticulum (ER), but the specific biological function of this modification is unclear. Here, we show that UFMylation facilitates proteasome-mediated degradation of arrest polypeptides (APs) which are generated following splitting of ribosomes that stall during co-translational translocation of secretory proteins into the ER. We propose that UFMylation weakens the tightly sealed ribosome-translocon junction, thereby allowing the cytosolic ubiquitin-proteasome and ribosome-associated quality control machineries to access ER-APs.
Collapse
Affiliation(s)
| | - Samantha C Gumbin
- Department of Molecular and Cellular Physiology, Stanford School of Medicine, Stanford CA, 94305
| | - Paul A DaRosa
- Department of Biology, Stanford University, Stanford CA, 94305
| | - Ron R Kopito
- Department of Biology, Stanford University, Stanford CA, 94305
| |
Collapse
|
9
|
Wang L, Xu Y, Yun S, Yuan Q, Satpute-Krishnan P, Ye Y. SAYSD1 senses UFMylated ribosome to safeguard co-translational protein translocation at the endoplasmic reticulum. Cell Rep 2023; 42:112028. [PMID: 36848233 PMCID: PMC10010011 DOI: 10.1016/j.celrep.2023.112028] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 11/17/2022] [Accepted: 01/09/2023] [Indexed: 01/24/2023] Open
Abstract
Translocon clogging at the endoplasmic reticulum (ER) as a result of translation stalling triggers ribosome UFMylation, activating translocation-associated quality control (TAQC) to degrade clogged substrates. How cells sense ribosome UFMylation to initiate TAQC is unclear. We conduct a genome-wide CRISPR-Cas9 screen to identify an uncharacterized membrane protein named SAYSD1 that facilitates TAQC. SAYSD1 associates with the Sec61 translocon and also recognizes both ribosome and UFM1 directly, engaging a stalled nascent chain to ensure its transport via the TRAPP complex to lysosomes for degradation. Like UFM1 deficiency, SAYSD1 depletion causes the accumulation of translocation-stalled proteins at the ER and triggers ER stress. Importantly, disrupting UFM1- and SAYSD1-dependent TAQC in Drosophila leads to intracellular accumulation of translocation-stalled collagens, defective collagen deposition, abnormal basement membranes, and reduced stress tolerance. Thus, SAYSD1 acts as a UFM1 sensor that collaborates with ribosome UFMylation at the site of clogged translocon, safeguarding ER homeostasis during animal development.
Collapse
Affiliation(s)
- Lihui Wang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yue Xu
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sijung Yun
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Quan Yuan
- Dendrite Morphogenesis and Plasticity Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Prasanna Satpute-Krishnan
- Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
| | - Yihong Ye
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| |
Collapse
|
10
|
Eisenack TJ, Trentini DB. Ending a bad start: Triggers and mechanisms of co-translational protein degradation. Front Mol Biosci 2023; 9:1089825. [PMID: 36660423 PMCID: PMC9846516 DOI: 10.3389/fmolb.2022.1089825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 12/15/2022] [Indexed: 01/05/2023] Open
Abstract
Proteins are versatile molecular machines that control and execute virtually all cellular processes. They are synthesized in a multilayered process requiring transfer of information from DNA to RNA and finally into polypeptide, with many opportunities for error. In addition, nascent proteins must successfully navigate a complex folding-energy landscape, in which their functional native state represents one of many possible outcomes. Consequently, newly synthesized proteins are at increased risk of misfolding and toxic aggregation. To maintain proteostasis-the state of proteome balance-cells employ a plethora of molecular chaperones that guide proteins along a productive folding pathway and quality control factors that direct misfolded species for degradation. Achieving the correct balance between folding and degradation therefore represents a fundamental task for the proteostasis network. While many chaperones act co-translationally, protein quality control is generally considered to be a post-translational process, as the majority of proteins will only achieve their final native state once translation is completed. Nevertheless, it has been observed that proteins can be ubiquitinated during synthesis. The extent and the relevance of co-translational protein degradation, as well as the underlying molecular mechanisms, remain areas of open investigation. Recent studies made seminal advances in elucidating ribosome-associated quality control processes, and how their loss of function can lead to proteostasis failure and disease. Here, we discuss current understanding of the situations leading to the marking of nascent proteins for degradation before synthesis is completed, and the emerging quality controls pathways engaged in this task in eukaryotic cells. We also highlight the methods used to study co-translational quality control.
Collapse
Affiliation(s)
- Tom Joshua Eisenack
- University of Cologne, Faculty of Medicine, University Hospital of Cologne, Center for Molecular Medicine Cologne (CMMC), Cologne, Germany
| | - Débora Broch Trentini
- University of Cologne, Faculty of Medicine, University Hospital of Cologne, Center for Molecular Medicine Cologne (CMMC), Cologne, Germany,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany,*Correspondence: Débora Broch Trentini,
| |
Collapse
|
11
|
Cytosolic Quality Control of Mitochondrial Protein Precursors-The Early Stages of the Organelle Biogenesis. Int J Mol Sci 2021; 23:ijms23010007. [PMID: 35008433 PMCID: PMC8745001 DOI: 10.3390/ijms23010007] [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: 11/19/2021] [Revised: 12/15/2021] [Accepted: 12/16/2021] [Indexed: 12/12/2022] Open
Abstract
With few exceptions, proteins that constitute the proteome of mitochondria originate outside of this organelle in precursor forms. Such protein precursors follow dedicated transportation paths to reach specific parts of mitochondria, where they complete their maturation and perform their functions. Mitochondrial precursor targeting and import pathways are essential to maintain proper mitochondrial function and cell survival, thus are tightly controlled at each stage. Mechanisms that sustain protein homeostasis of the cytosol play a vital role in the quality control of proteins targeted to the organelle. Starting from their synthesis, precursors are constantly chaperoned and guided to reduce the risk of premature folding, erroneous interactions, or protein damage. The ubiquitin-proteasome system provides proteolytic control that is not restricted to defective proteins but also regulates the supply of precursors to the organelle. Recent discoveries provide evidence that stress caused by the mislocalization of mitochondrial proteins may contribute to disease development. Precursors are not only subject to regulation but also modulate cytosolic machinery. Here we provide an overview of the cellular pathways that are involved in precursor maintenance and guidance at the early cytosolic stages of mitochondrial biogenesis. Moreover, we follow the circumstances in which mitochondrial protein import deregulation disturbs the cellular balance, carefully looking for rescue paths that can restore proteostasis.
Collapse
|
12
|
Rimal S, Li Y, Vartak R, Geng J, Tantray I, Li S, Huh S, Vogel H, Glabe C, Grinberg LT, Spina S, Seeley WW, Guo S, Lu B. Inefficient quality control of ribosome stalling during APP synthesis generates CAT-tailed species that precipitate hallmarks of Alzheimer's disease. Acta Neuropathol Commun 2021; 9:169. [PMID: 34663454 PMCID: PMC8522249 DOI: 10.1186/s40478-021-01268-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 09/26/2021] [Indexed: 11/25/2022] Open
Abstract
Amyloid precursor protein (APP) metabolism is central to Alzheimer's disease (AD) pathogenesis, but the key etiological driver remains elusive. Recent failures of clinical trials targeting amyloid-β (Aβ) peptides, the proteolytic fragments of amyloid precursor protein (APP) that are the main component of amyloid plaques, suggest that the proteostasis-disrupting, key pathogenic species remain to be identified. Previous studies suggest that APP C-terminal fragment (APP.C99) can cause disease in an Aβ-independent manner. The mechanism of APP.C99 pathogenesis is incompletely understood. We used Drosophila models expressing APP.C99 with the native ER-targeting signal of human APP, expressing full-length human APP only, or co-expressing full-length human APP and β-secretase (BACE), to investigate mechanisms of APP.C99 pathogenesis. Key findings are validated in mammalian cell culture models, mouse 5xFAD model, and postmortem AD patient brain materials. We find that ribosomes stall at the ER membrane during co-translational translocation of APP.C99, activating ribosome-associated quality control (RQC) to resolve ribosome collision and stalled translation. Stalled APP.C99 species with C-terminal extensions (CAT-tails) resulting from inadequate RQC are prone to aggregation, causing endolysosomal and autophagy defects and seeding the aggregation of amyloid β peptides, the main component of amyloid plaques. Genetically removing stalled and CAT-tailed APP.C99 rescued proteostasis failure, endolysosomal/autophagy dysfunction, neuromuscular degeneration, and cognitive deficits in AD models. Our finding of RQC factor deposition at the core of amyloid plaques from AD brains further supports the central role of defective RQC of ribosome collision and stalled translation in AD pathogenesis. These findings demonstrate that amyloid plaque formation is the consequence and manifestation of a deeper level proteostasis failure caused by inadequate RQC of translational stalling and the resultant aberrantly modified APP.C99 species, previously unrecognized etiological drivers of AD and newly discovered therapeutic targets.
Collapse
Affiliation(s)
- Suman Rimal
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Yu Li
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Rasika Vartak
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Ji Geng
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Ishaq Tantray
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Shuangxi Li
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Sungun Huh
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Hannes Vogel
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Charles Glabe
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA, USA
| | - Lea T Grinberg
- Memory and Aging Center, Department of Neurology and Department of Pathology, University of California, San Francisco, CA, 94158, USA
| | - Salvatore Spina
- Memory and Aging Center, Department of Neurology and Department of Pathology, University of California, San Francisco, CA, 94158, USA
| | - William W Seeley
- Memory and Aging Center, Department of Neurology and Department of Pathology, University of California, San Francisco, CA, 94158, USA
| | - Su Guo
- Department of Bioengineering and Therapeutic Sciences, Programs in Human Genetics and Biological Sciences, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, CA, USA
| | - Bingwei Lu
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| |
Collapse
|
13
|
Park J, Park J, Lee J, Lim C. The trinity of ribosome-associated quality control and stress signaling for proteostasis and neuronal physiology. BMB Rep 2021. [PMID: 34488933 PMCID: PMC8505234 DOI: 10.5483/bmbrep.2021.54.9.097] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Translating ribosomes accompany co-translational regulation of nascent polypeptide chains, including subcellular targeting, protein folding, and covalent modifications. Ribosome-associated quality control (RQC) is a co-translational surveillance mechanism triggered by ribosomal collisions, an indication of atypical translation. The ribosome-associated E3 ligase ZNF598 ubiquitinates small subunit proteins at the stalled ribosomes. A series of RQC factors are then recruited to dissociate and triage aberrant translation intermediates. Regulatory ribosomal stalling may occur on endogenous transcripts for quality gene expression, whereas ribosomal collisions are more globally induced by ribotoxic stressors such as translation inhibitors, ribotoxins, and UV radiation. The latter are sensed by ribosome-associated kinases GCN2 and ZAKα, activating integrated stress response (ISR) and ribotoxic stress response (RSR), respectively. Hierarchical crosstalks among RQC, ISR, and RSR pathways are readily detectable since the collided ribosome is their common substrate for activation. Given the strong implications of RQC factors in neuronal physiology and neurological disorders, the interplay between RQC and ribosome-associated stress signaling may sustain proteostasis, adaptively determine cell fate, and contribute to neural pathogenesis. The elucidation of underlying molecular principles in relevant human diseases should thus provide unexplored therapeutic opportunities.
Collapse
Affiliation(s)
- Jumin Park
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Jongmin Park
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Jongbin Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Chunghun Lim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| |
Collapse
|
14
|
Howard CJ, Frost A. Ribosome-associated quality control and CAT tailing. Crit Rev Biochem Mol Biol 2021; 56:603-620. [PMID: 34233554 DOI: 10.1080/10409238.2021.1938507] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Translation is the set of mechanisms by which ribosomes decode genetic messages as they synthesize polypeptides of a defined amino acid sequence. While the ribosome has been honed by evolution for high-fidelity translation, errors are inevitable. Aberrant mRNAs, mRNA structure, defective ribosomes, interactions between nascent proteins and the ribosomal exit tunnel, and insufficient cellular resources, including low tRNA levels, can lead to functionally irreversible stalls. Life thus depends on quality control mechanisms that detect, disassemble and recycle stalled translation intermediates. Ribosome-associated Quality Control (RQC) recognizes aberrant ribosome states and targets their potentially toxic polypeptides for degradation. Here we review recent advances in our understanding of RQC in bacteria, fungi, and metazoans. We focus in particular on an unusual modification made to the nascent chain known as a "CAT tail", or Carboxy-terminal Alanine and Threonine tail, and the mechanisms by which ancient RQC proteins catalyze CAT-tail synthesis.
Collapse
Affiliation(s)
- Conor J Howard
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA, USA
| |
Collapse
|
15
|
Yip MCJ, Shao S. Detecting and Rescuing Stalled Ribosomes. Trends Biochem Sci 2021; 46:731-743. [PMID: 33966939 DOI: 10.1016/j.tibs.2021.03.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/18/2021] [Accepted: 03/30/2021] [Indexed: 11/24/2022]
Abstract
Ribosomes that stall inappropriately during protein synthesis harbor proteotoxic components linked to cellular stress and neurodegenerative diseases. Molecular mechanisms that rescue stalled ribosomes must selectively detect rare aberrant translational complexes and process the heterogeneous components. Ribosome-associated quality control pathways eliminate problematic messenger RNAs and nascent proteins on stalled translational complexes. In addition, recent studies have uncovered general principles of stall recognition upstream of quality control pathways and fail-safe mechanisms that ensure nascent proteome integrity. Here, we discuss developments in our mechanistic understanding of the detection and rescue of stalled ribosomal complexes in eukaryotes.
Collapse
Affiliation(s)
- Matthew C J Yip
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA
| | - Sichen Shao
- Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.
| |
Collapse
|
16
|
Thrun A, Garzia A, Kigoshi-Tansho Y, Patil PR, Umbaugh CS, Dallinger T, Liu J, Kreger S, Patrizi A, Cox GA, Tuschl T, Joazeiro CAP. Convergence of mammalian RQC and C-end rule proteolytic pathways via alanine tailing. Mol Cell 2021; 81:2112-2122.e7. [PMID: 33909987 DOI: 10.1016/j.molcel.2021.03.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 01/28/2021] [Accepted: 03/02/2021] [Indexed: 12/22/2022]
Abstract
Incompletely synthesized nascent chains obstructing large ribosomal subunits are targeted for degradation by ribosome-associated quality control (RQC). In bacterial RQC, RqcH marks the nascent chains with C-terminal alanine (Ala) tails that are directly recognized by proteasome-like proteases, whereas in eukaryotes, RqcH orthologs (Rqc2/NEMF [nuclear export mediator factor]) assist the Ltn1/Listerin E3 ligase in nascent chain ubiquitylation. Here, we study RQC-mediated proteolytic targeting of ribosome stalling products in mammalian cells. We show that mammalian NEMF has an additional, Listerin-independent proteolytic role, which, as in bacteria, is mediated by tRNA-Ala binding and Ala tailing. However, in mammalian cells Ala tails signal proteolysis indirectly, through a pathway that recognizes C-terminal degrons; we identify the CRL2KLHDC10 E3 ligase complex and the novel C-end rule E3, Pirh2/Rchy1, as bona fide RQC pathway components that directly bind to Ala-tailed ribosome stalling products and target them for degradation. As Listerin mutation causes neurodegeneration in mice, functionally redundant E3s may likewise be implicated in molecular mechanisms of neurodegeneration.
Collapse
Affiliation(s)
- Anna Thrun
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Aitor Garzia
- Laboratory of RNA Molecular Biology, The Rockefeller University, New York, NY 10065, USA
| | - Yu Kigoshi-Tansho
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Pratik R Patil
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Charles S Umbaugh
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Teresa Dallinger
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Jia Liu
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Sylvia Kreger
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | - Annarita Patrizi
- Schaller Research Group Leader at the German Cancer Research Center, DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany
| | | | - Thomas Tuschl
- Laboratory of RNA Molecular Biology, The Rockefeller University, New York, NY 10065, USA
| | - Claudio A P Joazeiro
- Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBH Alliance, 69120 Heidelberg, Germany; Department of Molecular Medicine, Scripps Research, Jupiter, FL 33458, USA.
| |
Collapse
|
17
|
Wang L, Ye Y. Clearing Traffic Jams During Protein Translocation Across Membranes. Front Cell Dev Biol 2021; 8:610689. [PMID: 33490075 PMCID: PMC7820333 DOI: 10.3389/fcell.2020.610689] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 11/27/2020] [Indexed: 11/13/2022] Open
Abstract
Protein translocation across membranes is a critical facet of protein biogenesis in compartmentalized cells as proteins synthesized in the cytoplasm often need to traverse across lipid bilayers via proteinaceous channels to reach their final destinations. It is well established that protein biogenesis is tightly linked to various protein quality control processes, which monitor errors in protein folding, modification, and localization. However, little is known about how cells cope with translocation defective polypeptides that clog translocation channels (translocons) during protein translocation. This review summarizes recent studies, which collectively reveal a set of translocon-associated quality control strategies for eliminating polypeptides stuck in protein-conducting channels in the endoplasmic reticulum and mitochondria.
Collapse
Affiliation(s)
| | - Yihong Ye
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
| |
Collapse
|
18
|
Phillips BP, Miller EA. Ribosome-associated quality control of membrane proteins at the endoplasmic reticulum. J Cell Sci 2020; 133:133/22/jcs251983. [PMID: 33247003 PMCID: PMC7116877 DOI: 10.1242/jcs.251983] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Protein synthesis is an energetically costly, complex and risky process. Aberrant protein biogenesis can result in cellular toxicity and disease, with membrane-embedded proteins being particularly challenging for the cell. In order to protect the cell from consequences of defects in membrane proteins, quality control systems act to maintain protein homeostasis. The majority of these pathways act post-translationally; however, recent evidence reveals that membrane proteins are also subject to co-translational quality control during their synthesis in the endoplasmic reticulum (ER). This newly identified quality control pathway employs components of the cytosolic ribosome-associated quality control (RQC) machinery but differs from canonical RQC in that it responds to biogenesis state of the substrate rather than mRNA aberrations. This ER-associated RQC (ER-RQC) is sensitive to membrane protein misfolding and malfunctions in the ER insertion machinery. In this Review, we discuss the advantages of co-translational quality control of membrane proteins, as well as potential mechanisms of substrate recognition and degradation. Finally, we discuss some outstanding questions concerning future studies of ER-RQC of membrane proteins.
Collapse
Affiliation(s)
- Ben P Phillips
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | | |
Collapse
|
19
|
Runnebohm AM, Richards KA, Irelan CB, Turk SM, Vitali HE, Indovina CJ, Rubenstein EM. Overlapping function of Hrd1 and Ste24 in translocon quality control provides robust channel surveillance. J Biol Chem 2020; 295:16113-16120. [PMID: 33033070 DOI: 10.1074/jbc.ac120.016191] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/06/2020] [Indexed: 12/20/2022] Open
Abstract
Translocation of proteins across biological membranes is essential for life. Proteins that clog the endoplasmic reticulum (ER) translocon prevent the movement of other proteins into the ER. Eukaryotes have multiple translocon quality control (TQC) mechanisms to detect and destroy proteins that persistently engage the translocon. TQC mechanisms have been defined using a limited panel of substrates that aberrantly occupy the channel. The extent of substrate overlap among TQC pathways is unknown. In this study, we found that two TQC enzymes, the ER-associated degradation ubiquitin ligase Hrd1 and zinc metalloprotease Ste24, promote degradation of characterized translocon-associated substrates of the other enzyme in Saccharomyces cerevisiae Although both enzymes contribute to substrate turnover, our results suggest a prominent role for Hrd1 in TQC. Yeast lacking both Hrd1 and Ste24 exhibit a profound growth defect, consistent with overlapping function. Remarkably, two mutations that mildly perturb post-translational translocation and reduce the extent of aberrant translocon engagement by a model substrate diminish cellular dependence on TQC enzymes. Our data reveal previously unappreciated mechanistic complexity in TQC substrate detection and suggest that a robust translocon surveillance infrastructure maintains functional and efficient translocation machinery.
Collapse
Affiliation(s)
| | - Kyle A Richards
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | | | - Samantha M Turk
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | - Halie E Vitali
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | | | | |
Collapse
|
20
|
Ballhausen A, Przybilla MJ, Jendrusch M, Haupt S, Pfaffendorf E, Seidler F, Witt J, Hernandez Sanchez A, Urban K, Draxlbauer M, Krausert S, Ahadova A, Kalteis MS, Pfuderer PL, Heid D, Stichel D, Gebert J, Bonsack M, Schott S, Bläker H, Seppälä T, Mecklin JP, Ten Broeke S, Nielsen M, Heuveline V, Krzykalla J, Benner A, Riemer AB, von Knebel Doeberitz M, Kloor M. The shared frameshift mutation landscape of microsatellite-unstable cancers suggests immunoediting during tumor evolution. Nat Commun 2020; 11:4740. [PMID: 32958755 PMCID: PMC7506541 DOI: 10.1038/s41467-020-18514-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 08/21/2020] [Indexed: 02/06/2023] Open
Abstract
The immune system can recognize and attack cancer cells, especially those with a high load of mutation-induced neoantigens. Such neoantigens are abundant in DNA mismatch repair (MMR)-deficient, microsatellite-unstable (MSI) cancers. MMR deficiency leads to insertion/deletion (indel) mutations at coding microsatellites (cMS) and to neoantigen-inducing translational frameshifts. Here, we develop a tool to quantify frameshift mutations in MSI colorectal and endometrial cancer. Our results show that frameshift mutation frequency is negatively correlated to the predicted immunogenicity of the resulting peptides, suggesting counterselection of cell clones with highly immunogenic frameshift peptides. This correlation is absent in tumors with Beta-2-microglobulin mutations, and HLA-A*02:01 status is related to cMS mutation patterns. Importantly, certain outlier mutations are common in MSI cancers despite being related to frameshift peptides with functionally confirmed immunogenicity, suggesting a possible driver role during MSI tumor evolution. Neoantigens resulting from shared mutations represent promising vaccine candidates for prevention of MSI cancers.
Collapse
Affiliation(s)
- Alexej Ballhausen
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Moritz Jakob Przybilla
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Michael Jendrusch
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Saskia Haupt
- Engineering Mathematics and Computing Lab (EMCL), Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany
| | - Elisabeth Pfaffendorf
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Florian Seidler
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Johannes Witt
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Alejandro Hernandez Sanchez
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Katharina Urban
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Markus Draxlbauer
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Sonja Krausert
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Aysel Ahadova
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Martin Simon Kalteis
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Pauline L Pfuderer
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Daniel Heid
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Damian Stichel
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Clinical Cooperation Unit Neuropathology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Johannes Gebert
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Maria Bonsack
- Immunotherapy and Immunoprevention, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Vaccine Design, German Center for Infection Research (DZIF), partner site Heidelberg, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, Heidelberg, Germany
| | - Sarah Schott
- Department of Obstetrics and Gynecology, University Hospital Heidelberg, Heidelberg, Germany
| | - Hendrik Bläker
- Institute of Pathology, University Hospital Leipzig, Leipzig, Germany
| | - Toni Seppälä
- Department of Gastrointestinal Surgery, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Jukka-Pekka Mecklin
- Department of Education and Research, Central Finland Central Hospital, Jyväskylä, Finland
- Department of Sports and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Sanne Ten Broeke
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Maartje Nielsen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Vincent Heuveline
- Engineering Mathematics and Computing Lab (EMCL), Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany
| | - Julia Krzykalla
- Division of Biostatistics, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Axel Benner
- Division of Biostatistics, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Angelika Beate Riemer
- Immunotherapy and Immunoprevention, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Vaccine Design, German Center for Infection Research (DZIF), partner site Heidelberg, Heidelberg, Germany
| | - Magnus von Knebel Doeberitz
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany
| | - Matthias Kloor
- Department of Applied Tumor Biology, Institute of Pathology, University of Heidelberg, Heidelberg, Germany.
- Collaboration Unit Applied Tumor Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
- Molecular Medicine Partnership Unit (MMPU), Heidelberg University Hospital and EMBL, Heidelberg, Germany.
| |
Collapse
|
21
|
Abstract
Stalled protein synthesis produces defective nascent chains that can harm cells. In response, cells degrade these nascent chains via a process called ribosome-associated quality control (RQC). Here, we review the irregularities in the translation process that cause ribosomes to stall as well as how cells use RQC to detect stalled ribosomes, ubiquitylate their tethered nascent chains, and deliver the ubiquitylated nascent chains to the proteasome. We additionally summarize how cells respond to RQC failure.
Collapse
Affiliation(s)
- Cole S Sitron
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany;
| | - Onn Brandman
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA;
| |
Collapse
|
22
|
Richards KA, Rubenstein EM. Endoplasmic reticulum stress-regulated degradation of a translocon-associated protein is independent of integrated stress response transcription factor Gcn4p. MICROPUBLICATION BIOLOGY 2020; 2020:10.17912/micropub.biology.000239. [PMID: 32550483 PMCID: PMC7252232 DOI: 10.17912/micropub.biology.000239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Kyle A Richards
- Ball State University, Department of Biology, Muncie, IN 47306
| | - Eric M Rubenstein
- Ball State University, Department of Biology, Muncie, IN 47306,
Correspondence to: Eric M Rubenstein ()
| |
Collapse
|
23
|
Leznicki P, High S. SGTA associates with nascent membrane protein precursors. EMBO Rep 2020; 21:e48835. [PMID: 32216016 PMCID: PMC7202230 DOI: 10.15252/embr.201948835] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 02/25/2020] [Accepted: 02/28/2020] [Indexed: 01/15/2023] Open
Abstract
The endoplasmic reticulum (ER) is a major site for membrane protein synthesis in eukaryotes. The majority of integral membrane proteins are delivered to the ER membrane via the co‐translational, signal recognition particle (SRP)‐dependent route. However, tail‐anchored proteins employ an alternative, post‐translational route(s) that relies on distinct factors such as a cytosolic protein quality control component, SGTA. We now show that SGTA is selectively recruited to ribosomes synthesising a diverse range of membrane proteins, suggesting that its biosynthetic client base also includes precursors on the co‐translational ER delivery pathway. Strikingly, SGTA is recruited to nascent membrane proteins before their transmembrane domain emerges from the ribosome. Hence, SGTA is ideally placed to capture these aggregation prone regions shortly after their synthesis. For nascent membrane proteins on the co‐translational pathway, SGTA complements the role of SRP by reducing the co‐translational ubiquitination of clients with multiple hydrophobic signal sequences. On this basis, we propose that SGTA acts to mask specific transmembrane domains located in complex membrane proteins until they can engage the ER translocon and become membrane inserted.
Collapse
Affiliation(s)
- Pawel Leznicki
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Stephen High
- School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| |
Collapse
|
24
|
Joazeiro CAP. Mechanisms and functions of ribosome-associated protein quality control. Nat Rev Mol Cell Biol 2020; 20:368-383. [PMID: 30940912 DOI: 10.1038/s41580-019-0118-2] [Citation(s) in RCA: 242] [Impact Index Per Article: 60.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The stalling of ribosomes during protein synthesis results in the production of truncated polypeptides that can have deleterious effects on cells and therefore must be eliminated. In eukaryotes, this function is carried out by a dedicated surveillance mechanism known as ribosome-associated protein quality control (RQC). The E3 ubiquitin ligase Ltn1 (listerin in mammals) plays a key part in RQC by targeting the aberrant nascent polypeptides for proteasomal degradation. Consistent with having an important protein quality control function, mutations in listerin cause neurodegeneration in mice. Ltn1/listerin is part of the multisubunit RQC complex, and recent findings have revealed that the Rqc2 subunit of this complex catalyses the formation of carboxy-terminal alanine and threonine tails (CAT tails), which are extensions of nascent chains known to either facilitate substrate ubiquitylation and targeting for degradation or induce protein aggregation. RQC, originally described for quality control on ribosomes translating cytosolic proteins, is now known to also have a role on the surfaces of the endoplasmic reticulum and mitochondria. This Review describes our current knowledge on RQC mechanisms, highlighting key features of Ltn1/listerin action that provide a paradigm for understanding how E3 ligases operate in protein quality control in general, and discusses how defects in this pathway may compromise cellular function and lead to disease.
Collapse
Affiliation(s)
- Claudio A P Joazeiro
- Center for Molecular Biology of Heidelberg University (ZMBH), Heidelberg, Germany. .,Department of Molecular Medicine, Scripps Research, Jupiter, FL, USA.
| |
Collapse
|
25
|
Role for ribosome-associated quality control in sampling proteins for MHC class I-mediated antigen presentation. Proc Natl Acad Sci U S A 2020; 117:4099-4108. [PMID: 32047030 PMCID: PMC7049129 DOI: 10.1073/pnas.1914401117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Pathogens and tumors are detected by the immune system through the display of intracellular peptides on MHC-I complexes. These peptides are generated by the ubiquitin−proteasome system preferentially from newly synthesized polypeptides. Here we show that the ribosome-associated quality control (RQC) pathway, responsible for proteasomal degradation of polypeptide chains that stall during translation, mediates efficient antigen presentation of model proteins independent of their intrinsic folding properties. Immunopeptidome characterization of RQC-deficient cells shows that RQC contributes to the presentation of a wide variety of proteins, including proteins that may otherwise evade presentation due to efficient folding. By identifying endogenous substrates of the RQC pathway in human cells, our results also enable the analysis of common principles causing ribosome stalling under physiological conditions. Mammalian cells present a fingerprint of their proteome to the adaptive immune system through the display of endogenous peptides on MHC-I complexes. MHC-I−bound peptides originate from protein degradation by the proteasome, suggesting that stably folded, long-lived proteins could evade monitoring. Here, we investigate the role in antigen presentation of the ribosome-associated quality control (RQC) pathway for the degradation of nascent polypeptides that are encoded by defective messenger RNAs and undergo stalling at the ribosome during translation. We find that degradation of model proteins by RQC results in efficient MHC-I presentation, independent of their intrinsic folding properties. Quantitative profiling of MHC-I peptides in wild-type and RQC-deficient cells by mass spectrometry showed that RQC substantially contributes to the composition of the immunopeptidome. Our results also identify endogenous substrates of the RQC pathway in human cells and provide insight into common principles causing ribosome stalling under physiological conditions.
Collapse
|
26
|
Wang L, Xu Y, Rogers H, Saidi L, Noguchi CT, Li H, Yewdell JW, Guydosh NR, Ye Y. UFMylation of RPL26 links translocation-associated quality control to endoplasmic reticulum protein homeostasis. Cell Res 2020; 30:5-20. [PMID: 31595041 PMCID: PMC6951344 DOI: 10.1038/s41422-019-0236-6] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 09/06/2019] [Indexed: 12/19/2022] Open
Abstract
Protein biogenesis at the endoplasmic reticulum (ER) in eukaryotic cells is monitored by a protein quality control system named ER-associated protein degradation (ERAD). While there has been substantial progress in understanding how ERAD eliminates defective polypeptides generated from erroneous folding, how cells remove nascent chains stalled in the translocon during co-translational protein insertion into the ER is unclear. Here we show that ribosome stalling during protein translocation induces the attachment of UFM1, a ubiquitin-like modifier, to two conserved lysine residues near the COOH-terminus of the 60S ribosomal subunit RPL26 (uL24) at the ER. Strikingly, RPL26 UFMylation enables the degradation of stalled nascent chains, but unlike ERAD or previously established cytosolic ribosome-associated quality control (RQC), which uses proteasome to degrade their client proteins, ribosome UFMylation promotes the targeting of a translocation-arrested ER protein to lysosomes for degradation. RPL26 UFMylation is upregulated during erythroid differentiation to cope with increased secretory flow, and compromising UFMylation impairs protein secretion, and ultimately hemoglobin production. We propose that in metazoan, co-translational protein translocation into the ER is safeguarded by a UFMylation-dependent protein quality control mechanism, which when impaired causes anemia in mice and abnormal neuronal development in humans.
Collapse
Affiliation(s)
- Lihui Wang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yue Xu
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Heather Rogers
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Layla Saidi
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Constance Tom Noguchi
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Honglin Li
- Department of Biochemistry and Molecular Biology, Augusta University Medical Center, Augusta, GA, 30912, USA
| | - Jonathan Wilson Yewdell
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Nicholas Raymond Guydosh
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Yihong Ye
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA.
| |
Collapse
|
27
|
Buchanan BW, Mehrtash AB, Broshar CL, Runnebohm AM, Snow BJ, Scanameo LN, Hochstrasser M, Rubenstein EM. Endoplasmic reticulum stress differentially inhibits endoplasmic reticulum and inner nuclear membrane protein quality control degradation pathways. J Biol Chem 2019; 294:19814-19830. [PMID: 31723032 DOI: 10.1074/jbc.ra119.010295] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 11/04/2019] [Indexed: 12/29/2022] Open
Abstract
Endoplasmic reticulum (ER) stress occurs when the abundance of unfolded proteins in the ER exceeds the capacity of the folding machinery. Despite the expanding cadre of characterized cellular adaptations to ER stress, knowledge of the effects of ER stress on cellular physiology remains incomplete. We investigated the impact of ER stress on ER and inner nuclear membrane protein quality control mechanisms in Saccharomyces cerevisiae. We analyzed the turnover of substrates of four ubiquitin ligases (Doa10, Rkr1/Ltn1, Hrd1, and the Asi complex) and the metalloprotease Ste24 in induced models of ER stress. ER stress did not substantially impact Doa10 or Rkr1 substrates. However, Hrd1-mediated destruction of a protein that aberrantly engages the translocon (Deg1-Sec62) and substrates with luminal degradation signals was markedly impaired by ER stress; by contrast, Hrd1-dependent degradation of proteins with intramembrane degrons was largely unperturbed by ER stress. ER stress impaired the degradation of one of two Asi substrates analyzed and caused a translocon-clogging Ste24 substrate to accumulate in a form consistent with persistent translocon occupation. Degradation of Deg1-Sec62 in the absence of stress and stabilization during ER stress were independent of four ER stress-sensing pathways. Our results indicate ER stress differentially impacts degradation of protein quality control substrates, including those mediated by the same ubiquitin ligase. These observations suggest the existence of additional regulatory mechanisms dictating substrate selection during ER stress.
Collapse
Affiliation(s)
- Bryce W Buchanan
- Department of Biology, Ball State University, Muncie, Indiana 47306
| | - Adrian B Mehrtash
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520
| | | | | | - Brian J Snow
- Department of Biology, Ball State University, Muncie, Indiana 47306
| | - Laura N Scanameo
- Department of Biology, Ball State University, Muncie, Indiana 47306
| | - Mark Hochstrasser
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520
| | | |
Collapse
|
28
|
Quality Control across Compartments-Connecting ERAD with Ribosomal Quality Control. J Mol Biol 2019; 431:142-144. [PMID: 30503927 DOI: 10.1016/j.jmb.2018.11.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
29
|
Lang S, Nguyen D, Pfeffer S, Förster F, Helms V, Zimmermann R. Functions and Mechanisms of the Human Ribosome-Translocon Complex. Subcell Biochem 2019; 93:83-141. [PMID: 31939150 DOI: 10.1007/978-3-030-28151-9_4] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The membrane of the endoplasmic reticulum (ER) in human cells harbors the protein translocon, which facilitates membrane insertion and translocation of almost every newly synthesized polypeptide targeted to organelles of the secretory pathway. The translocon comprises the polypeptide-conducting Sec61 channel and several additional proteins, which are associated with the heterotrimeric Sec61 complex. This ensemble of proteins facilitates ER targeting of precursor polypeptides, Sec61 channel opening and closing, and modification of precursor polypeptides in transit through the Sec61 complex. Recently, cryoelectron tomography of translocons in native ER membranes has given unprecedented insights into the architecture and dynamics of the native, ribosome-associated translocon and the Sec61 channel. These structural data are discussed in light of different Sec61 channel activities including ribosome receptor function, membrane insertion or translocation of newly synthesized polypeptides as well as the possible roles of the Sec61 channel as a passive ER calcium leak channel and regulator of ATP/ADP exchange between cytosol and ER.
Collapse
Affiliation(s)
- Sven Lang
- Competence Center for Molecular Medicine, Saarland University Medical School, Building 44, 66421, Homburg, Germany.
| | - Duy Nguyen
- Center for Bioinformatics, Saarland University, 66041, Saarbrücken, Germany
| | - Stefan Pfeffer
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, 82152, Martinsried, Germany
- ZMBH, 69120, Heidelberg, Germany
| | - Friedrich Förster
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, 82152, Martinsried, Germany
- Center for Biomolecular Research, Utrecht University, 3584 CH, Utrecht, The Netherlands
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, 66041, Saarbrücken, Germany
| | - Richard Zimmermann
- Competence Center for Molecular Medicine, Saarland University Medical School, Building 44, 66421, Homburg, Germany
| |
Collapse
|
30
|
Cesaratto F, Sasset L, Myers MP, Re A, Petris G, Burrone OR. BiP/GRP78 Mediates ERAD Targeting of Proteins Produced by Membrane-Bound Ribosomes Stalled at the STOP-Codon. J Mol Biol 2018; 431:123-141. [PMID: 30367842 PMCID: PMC7094721 DOI: 10.1016/j.jmb.2018.10.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 10/15/2018] [Accepted: 10/16/2018] [Indexed: 11/29/2022]
Abstract
Translational stalling of ribosome bound to endoplasmic reticulum (ER) membrane requires an accurate clearance of the associated polypeptides, which is not completely understood in mammals. We characterized in mammalian cells the model of ribosomal stalling at the STOP-codon based on proteins tagged at the C-terminus with the picornavirus 2A peptide followed by a termination codon instead of the Proline (2A*). We exploited the 2A* stalling model to characterize the pathway of degradation of ER-targeted polypeptides. We report that the ER chaperone BiP/GRP78 is a new main factor involved. Moreover, degradation of the ER-stalled polypeptides required the activities of the AAA-ATPase VCP/p97, its associated deubiquitinylase YOD1, the ribosome-associated ubiquitin ligase Listerin and the proteasome. In human proteome, we found two human C-terminal amino acid sequences that cause similar stalling at the STOP-codon. Our data suggest that translational stalling at the ER membrane activates protein degradation at the interface of ribosomal- and ER-associated quality control systems. Ribosomal stalling at the STOP-codon causes degradation of the translated protein. Picornavirus 2A peptide and related sequences cause ribosome stalling at STOP-codon. BiP/GRP78 recognizes polypeptides produced by membrane-bound stalled ribosomes. ER-stalled polypeptides are disposed of through the ERAD pathway. BIP/GRP78 is a novel key player for ERAD targeting of stalled ribosomal peptides.
Collapse
Affiliation(s)
- Francesca Cesaratto
- Laboratory of Molecular Immunology, International Centre for Genetic Engineering and Biotechnology, ICGEB, Padriciano 99, 34149 Trieste, Italy
| | - Linda Sasset
- Laboratory of Molecular Immunology, International Centre for Genetic Engineering and Biotechnology, ICGEB, Padriciano 99, 34149 Trieste, Italy
| | - Michael P Myers
- Laboratory of Protein Networks, International Centre for Genetic Engineering and Biotechnology, ICGEB, Padriciano 99, 34149 Trieste, Italy
| | - Angela Re
- Centre for Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy; Center for Sustainable Future Technologies, Fondazione Istituto Italiano di Tecnologia, C.so Trento 21, 10129 Torino, Italy; Center for Sustainable Future Technologies, Fondazione Istituto Italiano di Tecnologia, C.so Trento 21, 10129 Torino, Italy
| | - Gianluca Petris
- Centre for Integrative Biology (CIBIO), University of Trento, Via Sommarive 9, 38123 Trento, Italy.
| | - Oscar R Burrone
- Laboratory of Molecular Immunology, International Centre for Genetic Engineering and Biotechnology, ICGEB, Padriciano 99, 34149 Trieste, Italy.
| |
Collapse
|
31
|
Mehrtash AB, Hochstrasser M. Ubiquitin-dependent protein degradation at the endoplasmic reticulum and nuclear envelope. Semin Cell Dev Biol 2018; 93:111-124. [PMID: 30278225 DOI: 10.1016/j.semcdb.2018.09.013] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 09/26/2018] [Accepted: 09/27/2018] [Indexed: 01/01/2023]
Abstract
Numerous nascent proteins undergo folding and maturation within the luminal and membrane compartments of the endoplasmic reticulum (ER). Despite the presence of various factors in the ER that promote protein folding, many proteins fail to properly fold and assemble and are subsequently degraded. Regulatory proteins in the ER also undergo degradation in a way that is responsive to stimuli or the changing needs of the cell. As in most cellular compartments, the ubiquitin-proteasome system (UPS) is responsible for the majority of the degradation at the ER-in a process termed ER-associated degradation (ERAD). Autophagic processes utilizing ubiquitin-like protein-conjugating systems also play roles in protein degradation at the ER. The ER is continuous with the nuclear envelope (NE), which consists of the outer nuclear membrane (ONM) and inner nuclear membrane (INM). While ERAD is known also to occur at the NE, only some of the ERAD ubiquitin-ligation pathways function at the INM. Protein degradation machineries in the ER/NE target a wide variety of substrates in multiple cellular compartments, including the cytoplasm, nucleoplasm, ER lumen, ER membrane, and the NE. Here, we review the protein degradation machineries of the ER and NE and the underlying mechanisms dictating recognition and processing of substrates by these machineries.
Collapse
Affiliation(s)
- Adrian B Mehrtash
- Department of Molecular, Cellular, & Developmental Biology, Yale University, New Haven, 06520, CT, USA.
| | - Mark Hochstrasser
- Department of Molecular Biophysics & Biochemistry, Yale University, New Haven, CT, 06520, USA; Department of Molecular, Cellular, & Developmental Biology, Yale University, New Haven, 06520, CT, USA.
| |
Collapse
|
32
|
Verma R, Reichermeier KM, Burroughs AM, Oania RS, Reitsma JM, Aravind L, Deshaies RJ. Vms1 and ANKZF1 peptidyl-tRNA hydrolases release nascent chains from stalled ribosomes. Nature 2018; 557:446-451. [PMID: 29632312 PMCID: PMC6226276 DOI: 10.1038/s41586-018-0022-5] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 02/08/2018] [Indexed: 11/30/2022]
Affiliation(s)
- Rati Verma
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA.,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Amgen Discovery Research, Thousand Oaks, CA, USA
| | - Kurt M Reichermeier
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Genentech, South San Francisco, CA, USA
| | - A Maxwell Burroughs
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Robert S Oania
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA.,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Justin M Reitsma
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - L Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA.
| | - Raymond J Deshaies
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA. .,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA. .,Amgen Discovery Research, Thousand Oaks, CA, USA.
| |
Collapse
|
33
|
Zuzow N, Ghosh A, Leonard M, Liao J, Yang B, Bennett EJ. Mapping the mammalian ribosome quality control complex interactome using proximity labeling approaches. Mol Biol Cell 2018. [PMID: 29540532 PMCID: PMC5935074 DOI: 10.1091/mbc.e17-12-0714] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Previous genetic and biochemical studies from Saccharomyces cerevisiae have identified a critical ribosome-associated quality control complex (RQC) that facilitates resolution of stalled ribosomal complexes. While components of the mammalian RQC have been examined in vitro, a systematic characterization of RQC protein interactions in mammalian cells has yet to be described. Here we utilize both proximity-labeling proteomic approaches, BioID and APEX, and traditional affinity-based strategies to both identify interacting proteins of mammalian RQC members and putative substrates for the RQC resident E3 ligase, Ltn1. Surprisingly, validation studies revealed that a subset of substrates are ubiquitylated by Ltn1 in a regulatory manner that does not result in subsequent substrate degradation. We demonstrate that Ltn1 catalyzes the regulatory ubiquitylation of ribosomal protein S6 kinase 1 and 2 (RPS6KA1, RPS6KA3). Further, loss of Ltn1 function results in hyperactivation of RSK1/2 signaling without impacting RSK1/2 protein turnover. These results suggest that Ltn1-mediated RSK1/2 ubiquitylation is inhibitory and establishes a new role for Ltn1 in regulating mitogen-activated kinase signaling via regulatory RSK1/2 ubiquitylation. Taken together, our results suggest that mammalian RQC interactions are difficult to observe and may be more transient than the homologous complex in S. cerevisiae and that Ltn1 has RQC-independent functions.
Collapse
Affiliation(s)
- Nathan Zuzow
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Arit Ghosh
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Marilyn Leonard
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Jeffrey Liao
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Bing Yang
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Eric J Bennett
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093
| |
Collapse
|
34
|
Bragoszewski P, Turek M, Chacinska A. Control of mitochondrial biogenesis and function by the ubiquitin-proteasome system. Open Biol 2018; 7:rsob.170007. [PMID: 28446709 PMCID: PMC5413908 DOI: 10.1098/rsob.170007] [Citation(s) in RCA: 135] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 03/31/2017] [Indexed: 12/17/2022] Open
Abstract
Mitochondria are pivotal organelles in eukaryotic cells. The complex proteome of mitochondria comprises proteins that are encoded by nuclear and mitochondrial genomes. The biogenesis of mitochondrial proteins requires their transport in an unfolded state with a high risk of misfolding. The mislocalization of mitochondrial proteins is deleterious to the cell. The electron transport chain in mitochondria is a source of reactive oxygen species that damage proteins. Mitochondrial dysfunction is linked to many pathological conditions and, together with the loss of cellular protein homeostasis (proteostasis), are hallmarks of ageing and ageing-related degeneration diseases. The pathogenesis of neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease, has been associated with mitochondrial and proteostasis failure. Thus, mitochondrial proteins require sophisticated surveillance mechanisms. Although mitochondria form a proteasome-exclusive compartment, multiple lines of evidence indicate a crucial role for the cytosolic ubiquitin-proteasome system (UPS) in the quality control of mitochondrial proteins. The proteasome affects mitochondrial proteins at stages of their biogenesis and maturity. The effects of the UPS go beyond the removal of damaged proteins and include the adjustment of mitochondrial proteome composition, the regulation of organelle dynamics and the protection of cellular homeostasis against mitochondrial failure. In turn, mitochondrial activity and mitochondrial dysfunction adjust the activity of the UPS, with implications at the cellular level.
Collapse
Affiliation(s)
- Piotr Bragoszewski
- Laboratory of Mitochondrial Biogenesis, International Institute of Molecular and Cell Biology, Ks. Trojdena 4, 02-109 Warsaw, Poland
| | - Michal Turek
- Laboratory of Mitochondrial Biogenesis, International Institute of Molecular and Cell Biology, Ks. Trojdena 4, 02-109 Warsaw, Poland
| | - Agnieszka Chacinska
- Laboratory of Mitochondrial Biogenesis, International Institute of Molecular and Cell Biology, Ks. Trojdena 4, 02-109 Warsaw, Poland .,Centre of New Technologies, Warsaw University, Banacha 2c, 02-097 Warsaw, Poland
| |
Collapse
|
35
|
Lang S, Pfeffer S, Lee PH, Cavalié A, Helms V, Förster F, Zimmermann R. An Update on Sec61 Channel Functions, Mechanisms, and Related Diseases. Front Physiol 2017; 8:887. [PMID: 29163222 PMCID: PMC5672155 DOI: 10.3389/fphys.2017.00887] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 10/19/2017] [Indexed: 12/18/2022] Open
Abstract
The membrane of the endoplasmic reticulum (ER) of nucleated human cells harbors the protein translocon, which facilitates membrane integration or translocation of almost every newly synthesized polypeptide targeted to organelles of the endo- and exocytotic pathway. The translocon comprises the polypeptide-conducting Sec61 channel and several additional proteins and complexes that are permanently or transiently associated with the heterotrimeric Sec61 complex. This ensemble of proteins facilitates ER targeting of precursor polypeptides, modification of precursor polypeptides in transit through the Sec61 complex, and Sec61 channel gating, i.e., dynamic regulation of the pore forming subunit to mediate precursor transport and calcium efflux. Recently, cryoelectron tomography of translocons in native ER membrane vesicles, derived from human cell lines or patient fibroblasts, and even intact cells has given unprecedented insights into the architecture and dynamics of the native translocon and the Sec61 channel. These structural data are discussed in light of different Sec61 channel activities including ribosome receptor function, membrane insertion, and translocation of newly synthesized polypeptides as well as the putative physiological roles of the Sec61 channel as a passive ER calcium leak channel. Furthermore, the structural insights into the Sec61 channel are incorporated into an overview and update on Sec61 channel-related diseases—the Sec61 channelopathies—and novel therapeutic concepts for their treatment.
Collapse
Affiliation(s)
- Sven Lang
- Competence Center for Molecular Medicine, Saarland University Medical School, Homburg, Germany
| | - Stefan Pfeffer
- Department of Molecular Structural Biology, Max-Planck Institute of Biochemistry, Martinsried, Germany
| | - Po-Hsien Lee
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Adolfo Cavalié
- Experimental and Clinical Pharmacology and Toxicology, Saarland University, Homburg, Germany
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Friedrich Förster
- Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht, Netherlands
| | - Richard Zimmermann
- Competence Center for Molecular Medicine, Saarland University Medical School, Homburg, Germany
| |
Collapse
|
36
|
Izawa T, Park SH, Zhao L, Hartl FU, Neupert W. Cytosolic Protein Vms1 Links Ribosome Quality Control to Mitochondrial and Cellular Homeostasis. Cell 2017; 171:890-903.e18. [PMID: 29107329 DOI: 10.1016/j.cell.2017.10.002] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 07/15/2017] [Accepted: 09/27/2017] [Indexed: 01/09/2023]
Abstract
Eukaryotic cells have evolved extensive protein quality-control mechanisms to remove faulty translation products. Here, we show that yeast cells continually produce faulty mitochondrial polypeptides that stall on the ribosome during translation but are imported into the mitochondria. The cytosolic protein Vms1, together with the E3 ligase Ltn1, protects against the mitochondrial toxicity of these proteins and maintains cell viability under respiratory conditions. In the absence of these factors, stalled polypeptides aggregate after import and sequester critical mitochondrial chaperone and translation machinery. Aggregation depends on C-terminal alanyl/threonyl sequences (CAT-tails) that are attached to stalled polypeptides on 60S ribosomes by Rqc2. Vms1 binds to 60S ribosomes at the mitochondrial surface and antagonizes Rqc2, thereby facilitating import, impeding aggregation, and directing aberrant polypeptides to intra-mitochondrial quality control. Vms1 is a key component of a rescue pathway for ribosome-stalled mitochondrial polypeptides that are inaccessible to ubiquitylation due to coupling of translation and translocation.
Collapse
Affiliation(s)
- Toshiaki Izawa
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany; Division of Cell Biology, Biomedical Center, Faculty of Medicine, University of Munich, Großhaderner Strasse 9, 82152 Martinsried, Germany
| | - Sae-Hun Park
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Liang Zhao
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - F Ulrich Hartl
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
| | - Walter Neupert
- Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany; Division of Cell Biology, Biomedical Center, Faculty of Medicine, University of Munich, Großhaderner Strasse 9, 82152 Martinsried, Germany.
| |
Collapse
|
37
|
Engle SM, Crowder JJ, Watts SG, Indovina CJ, Coffey SZ, Rubenstein EM. Acetylation of N-terminus and two internal amino acids is dispensable for degradation of a protein that aberrantly engages the endoplasmic reticulum translocon. PeerJ 2017; 5:e3728. [PMID: 28848693 PMCID: PMC5571791 DOI: 10.7717/peerj.3728] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 08/02/2017] [Indexed: 12/26/2022] Open
Abstract
Conserved homologues of the Hrd1 ubiquitin ligase target for degradation proteins that persistently or aberrantly engage the endoplasmic reticulum translocon, including mammalian apolipoprotein B (apoB; the major protein component of low-density lipoproteins) and the artificial yeast protein Deg1-Sec62. A complete understanding of the molecular mechanism by which translocon-associated proteins are recognized and degraded may inform the development of therapeutic strategies for cholesterol-related pathologies. Both apoB and Deg1-Sec62 are extensively post-translationally modified. Mass spectrometry of a variant of Deg1-Sec62 revealed that the protein is acetylated at the N-terminal methionine and two internal lysine residues. N-terminal and internal acetylation regulates the degradation of a variety of unstable proteins. However, preventing N-terminal and internal acetylation had no detectable consequence for Hrd1-mediated proteolysis of Deg1-Sec62. Our data highlight the importance of empirically validating the role of post-translational modifications and sequence motifs on protein degradation, even when such elements have previously been demonstrated sufficient to destine other proteins for destruction.
Collapse
Affiliation(s)
- Sarah M Engle
- Department of Biology, Ball State University, Muncie, IN, United States of America.,Immunology-Translational Science, Eli Lilly and Company, Indianapolis, IN, United States of America
| | - Justin J Crowder
- Department of Biology, Ball State University, Muncie, IN, United States of America.,Center for Medical Education, Indiana University School of Medicine, Muncie, IN, United States of America
| | - Sheldon G Watts
- Department of Biology, Ball State University, Muncie, IN, United States of America.,Marian University College of Osteopathic Medicine, Indianapolis, IN, United States of America
| | | | - Samuel Z Coffey
- Department of Biology, Ball State University, Muncie, IN, United States of America.,Medpace Reference Laboratories, Cincinnati, OH, United States of America
| | - Eric M Rubenstein
- Department of Biology, Ball State University, Muncie, IN, United States of America
| |
Collapse
|
38
|
Kostova KK, Hickey KL, Osuna BA, Hussmann JA, Frost A, Weinberg DE, Weissman JS. CAT-tailing as a fail-safe mechanism for efficient degradation of stalled nascent polypeptides. Science 2017; 357:414-417. [PMID: 28751611 PMCID: PMC5673106 DOI: 10.1126/science.aam7787] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Revised: 05/04/2017] [Accepted: 06/28/2017] [Indexed: 12/27/2022]
Abstract
Ribosome stalling leads to recruitment of the ribosome quality control complex (RQC), which targets the partially synthesized polypeptide for proteasomal degradation through the action of the ubiquitin ligase Ltn1p. A second core RQC component, Rqc2p, modifies the nascent polypeptide by adding a carboxyl-terminal alanine and threonine (CAT) tail through a noncanonical elongation reaction. Here we examined the role of CAT-tailing in nascent-chain degradation in budding yeast. We found that Ltn1p efficiently accessed only nascent-chain lysines immediately proximal to the ribosome exit tunnel. For substrates without Ltn1p-accessible lysines, CAT-tailing enabled degradation by exposing lysines sequestered in the ribosome exit tunnel. Thus, CAT-tails do not serve as a degron, but rather provide a fail-safe mechanism that expands the range of RQC-degradable substrates.
Collapse
Affiliation(s)
- Kamena K Kostova
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Kelsey L Hickey
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Beatriz A Osuna
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Jeffrey A Hussmann
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
- California Institute for Quantitative Biomedical Research, University of California, San Francisco, San Francisco, CA 94158, USA
- Department of Biochemistry, University of Utah, Salt Lake City, UT 84112, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - David E Weinberg
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA.
| | - Jonathan S Weissman
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA.
- Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158, USA
- California Institute for Quantitative Biomedical Research, University of California, San Francisco, San Francisco, CA 94158, USA
- Center for RNA Systems Biology, University of California, San Francisco, San Francisco, CA 94158, USA
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| |
Collapse
|
39
|
Defenouillère Q, Fromont-Racine M. The ribosome-bound quality control complex: from aberrant peptide clearance to proteostasis maintenance. Curr Genet 2017; 63:997-1005. [PMID: 28528489 DOI: 10.1007/s00294-017-0708-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 05/16/2017] [Accepted: 05/17/2017] [Indexed: 01/01/2023]
Abstract
Proteostasis in eukaryotes is maintained by compartment-specific quality control pathways, which enable the refolding or the degradation of defective polypeptides to prevent the toxicity that may arise from their aggregation. Among these processes, translational protein quality control is performed by the Ribosome-bound Quality Control complex (RQC), which recognizes nascent peptides translated from aberrant mRNAs, polyubiquitylates these aberrant peptides, extracts them from the stalled 60S subunit and finally escorts them to the proteasome for degradation. In this review, we focus on the mechanism of action of the RQC complex from stalled 60S binding to aberrant peptide delivery to the proteasome and describe the cellular consequences of a deficiency in the RQC pathway, such as aberrant protein aggregation. In addition, this review covers the recent discoveries concerning the role of cytosolic chaperones, as well as Tom1, to prevent the accumulation of aberrant protein aggregates in case of a deficiency in the RQC pathway.
Collapse
Affiliation(s)
- Quentin Defenouillère
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, 75724, Paris Cedex 15, France. .,Membrane Trafficking, Ubiquitin and Signaling, Institut Jacques Monod, UMR7592 CNRS/Université Paris-Diderot, 15 Rue Hélène Brion, Bât. Buffon, 75205, Paris Cedex 13, France.
| | - Micheline Fromont-Racine
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, 75724, Paris Cedex 15, France
| |
Collapse
|
40
|
Defenouillère Q, Namane A, Mouaikel J, Jacquier A, Fromont-Racine M. The ribosome-bound quality control complex remains associated to aberrant peptides during their proteasomal targeting and interacts with Tom1 to limit protein aggregation. Mol Biol Cell 2017; 28:1165-1176. [PMID: 28298488 PMCID: PMC5415013 DOI: 10.1091/mbc.e16-10-0746] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 03/03/2017] [Accepted: 03/03/2017] [Indexed: 11/16/2022] Open
Abstract
The RQC complex involved in protein quality control mechanisms also exists as a ribosome-unbound complex during the escort of aberrant peptides to the proteasome. The E3 ubiquitin ligase Tom1 is a newly identified partner of this light version of the RQC complex and is required for aggregate prevention. Protein quality control mechanisms eliminate defective polypeptides to ensure proteostasis and to avoid the toxicity of protein aggregates. In eukaryotes, the ribosome-bound quality control (RQC) complex detects aberrant nascent peptides that remain stalled in 60S ribosomal particles due to a dysfunction in translation termination. The RQC complex polyubiquitylates aberrant polypeptides and recruits a Cdc48 hexamer to extract them from 60S particles in order to escort them to the proteasome for degradation. Whereas the steps from stalled 60S recognition to aberrant peptide polyubiquitylation by the RQC complex have been described, the mechanism leading to proteasomal degradation of these defective translation products remains unknown. We show here that the RQC complex also exists as a ribosome-unbound complex during the escort of aberrant peptides to the proteasome. In addition, we identify a new partner of this light version of the RQC complex, the E3 ubiquitin ligase Tom1. Tom1 interacts with aberrant nascent peptides and is essential to limit their accumulation and aggregation in the absence of Rqc1; however, its E3 ubiquitin ligase activity is not required. Taken together, these results reveal new roles for Tom1 in protein quality control, aggregate prevention, and, therefore, proteostasis maintenance.
Collapse
Affiliation(s)
- Quentin Defenouillère
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, F-75724 Paris Cedex 15, France.,Sorbonne Universités, UPMC Paris 6, Complexité Du Vivant, 75252 Paris Cedex 05, France
| | - Abdelkader Namane
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, F-75724 Paris Cedex 15, France
| | - John Mouaikel
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, F-75724 Paris Cedex 15, France
| | - Alain Jacquier
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, F-75724 Paris Cedex 15, France
| | - Micheline Fromont-Racine
- Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, UMR 3525, F-75724 Paris Cedex 15, France
| |
Collapse
|
41
|
Strøm TB, Laerdahl JK, Leren TP. Mutations affecting the transmembrane domain of the LDL receptor: impact of charged residues on the membrane insertion. Hum Mol Genet 2017; 26:1634-1642. [DOI: 10.1093/hmg/ddx068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 02/17/2017] [Indexed: 12/11/2022] Open
|
42
|
Quality control of nonstop membrane proteins at the ER membrane and in the cytosol. Sci Rep 2016; 6:30795. [PMID: 27481473 PMCID: PMC4969602 DOI: 10.1038/srep30795] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 07/11/2016] [Indexed: 11/08/2022] Open
Abstract
Since messenger RNAs without a stop codon (nonstop mRNAs) for organelle-targeted proteins and their translation products (nonstop proteins) generate clogged translocon channels as well as stalled ribosomes, cells have mechanisms to degrade nonstop mRNAs and nonstop proteins and to clear the translocons (e.g. the Sec61 complex) by release of nonstop proteins into the organellar lumen. Here we followed the fate of nonstop endoplasmic reticulum (ER) membrane proteins with different membrane topologies in yeast to evaluate the importance of the Ltn1-dependent cytosolic degradation and the Dom34-dependent release of the nonstop membrane proteins. Ltn1-dependent degradation differed for membrane proteins with different topologies and its failure did not affect ER protein import or cell growth. On the other hand, failure in the Dom34-dependent release of the nascent polypeptide from the ribosome led to the block of the Sec61 channel and resultant inhibition of other protein import into the ER caused cell growth defects. Therefore, the nascent chain release from the translation apparatus is more instrumental in clearance of the clogged ER translocon channel and thus maintenance of normal cellular functions.
Collapse
|
43
|
Shcherbik N, Chernova TA, Chernoff YO, Pestov DG. Distinct types of translation termination generate substrates for ribosome-associated quality control. Nucleic Acids Res 2016; 44:6840-52. [PMID: 27325745 PMCID: PMC5001609 DOI: 10.1093/nar/gkw566] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2016] [Accepted: 06/13/2016] [Indexed: 11/24/2022] Open
Abstract
Cotranslational degradation of polypeptide nascent chains plays a critical role in quality control of protein synthesis and the rescue of stalled ribosomes. In eukaryotes, ribosome stalling triggers release of 60S subunits with attached nascent polypeptides, which undergo ubiquitination by the E3 ligase Ltn1 and proteasomal degradation facilitated by the ATPase Cdc48. However, the identity of factors acting upstream in this process is less clear. Here, we examined how the canonical release factors Sup45–Sup35 (eRF1–eRF3) and their paralogs Dom34-Hbs1 affect the total population of ubiquitinated nascent chains associated with yeast ribosomes. We found that the availability of the functional release factor complex Sup45–Sup35 strongly influences the amount of ubiquitinated polypeptides associated with 60S ribosomal subunits, while Dom34-Hbs1 generate 60S-associated peptidyl-tRNAs that constitute a relatively minor fraction of Ltn1 substrates. These results uncover two separate pathways that target nascent polypeptides for Ltn1-Cdc48-mediated degradation and suggest that in addition to canonical termination on stop codons, eukaryotic release factors contribute to cotranslational protein quality control.
Collapse
Affiliation(s)
- Natalia Shcherbik
- Department of Cell Biology, Rowan University, School of Osteopathic Medicine, Stratford, NJ 08084, USA
| | - Tatiana A Chernova
- Department of Biochemistry, Emory University, School of Medicine, Atlanta, GA 30322, USA
| | - Yury O Chernoff
- School of Biology, Georgia Institute of Technology, Atlanta, GA 30322, USA Laboratory of Amyloid Biology & Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg 199034, Russia
| | - Dimitri G Pestov
- Department of Cell Biology, Rowan University, School of Osteopathic Medicine, Stratford, NJ 08084, USA
| |
Collapse
|
44
|
Ast T, Michaelis S, Schuldiner M. The Protease Ste24 Clears Clogged Translocons. Cell 2016; 164:103-114. [PMID: 26771486 DOI: 10.1016/j.cell.2015.11.053] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 09/23/2015] [Accepted: 11/17/2015] [Indexed: 01/12/2023]
Abstract
Translocation into the endoplasmic reticulum (ER) is the first step in the biogenesis of thousands of eukaryotic endomembrane proteins. Although functional ER translocation has been avidly studied, little is known about the quality control mechanisms that resolve faulty translocational states. One such faulty state is translocon clogging, in which the substrate fails to properly translocate and obstructs the translocon pore. To shed light on the machinery required to resolve clogging, we carried out a systematic screen in Saccharomyces cerevisiae that highlighted a role for the ER metalloprotease Ste24. We could demonstrate that Ste24 approaches the translocon upon clogging, and it interacts with and generates cleavage fragments of the clogged protein. Importantly, these functions are conserved in the human homolog, ZMPSTE24, although disease-associated mutant forms of ZMPSTE24 fail to clear the translocon. These results shed light on a new and critical task of Ste24, which safeguards the essential process of translocation.
Collapse
Affiliation(s)
- Tslil Ast
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Susan Michaelis
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel.
| |
Collapse
|
45
|
Ribosome-associated protein quality control. Nat Struct Mol Biol 2016; 23:7-15. [PMID: 26733220 DOI: 10.1038/nsmb.3147] [Citation(s) in RCA: 294] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 11/23/2015] [Indexed: 12/18/2022]
Abstract
Protein synthesis by the ribosome can fail for numerous reasons including faulty mRNA, insufficient availability of charged tRNAs and genetic errors. All organisms have evolved mechanisms to recognize stalled ribosomes and initiate pathways for recycling, quality control and stress signaling. Here we review the discovery and molecular dissection of the eukaryotic ribosome-associated quality-control pathway for degradation of nascent polypeptides arising from interrupted translation.
Collapse
|
46
|
Ellgaard L, McCaul N, Chatsisvili A, Braakman I. Co- and Post-Translational Protein Folding in the ER. Traffic 2016; 17:615-38. [PMID: 26947578 DOI: 10.1111/tra.12392] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 02/26/2016] [Accepted: 03/03/2016] [Indexed: 12/19/2022]
Abstract
The biophysical rules that govern folding of small, single-domain proteins in dilute solutions are now quite well understood. The mechanisms underlying co-translational folding of multidomain and membrane-spanning proteins in complex cellular environments are often less clear. The endoplasmic reticulum (ER) produces a plethora of membrane and secretory proteins, which must fold and assemble correctly before ER exit - if these processes fail, misfolded species accumulate in the ER or are degraded. The ER differs from other cellular organelles in terms of the physicochemical environment and the variety of ER-specific protein modifications. Here, we review chaperone-assisted co- and post-translational folding and assembly in the ER and underline the influence of protein modifications on these processes. We emphasize how method development has helped advance the field by allowing researchers to monitor the progression of folding as it occurs inside living cells, while at the same time probing the intricate relationship between protein modifications during folding.
Collapse
Affiliation(s)
- Lars Ellgaard
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Nicholas McCaul
- Cellular Protein Chemistry, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Anna Chatsisvili
- Cellular Protein Chemistry, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Ineke Braakman
- Cellular Protein Chemistry, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| |
Collapse
|
47
|
Crowder JJ, Geigges M, Gibson RT, Fults ES, Buchanan BW, Sachs N, Schink A, Kreft SG, Rubenstein EM. Rkr1/Ltn1 Ubiquitin Ligase-mediated Degradation of Translationally Stalled Endoplasmic Reticulum Proteins. J Biol Chem 2015; 290:18454-66. [PMID: 26055716 DOI: 10.1074/jbc.m115.663559] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Indexed: 11/06/2022] Open
Abstract
Aberrant nonstop proteins arise from translation of mRNA molecules beyond the coding sequence into the 3'-untranslated region. If a stop codon is not encountered, translation continues into the poly(A) tail, resulting in C-terminal appendage of a polylysine tract and a terminally stalled ribosome. In Saccharomyces cerevisiae, the ubiquitin ligase Rkr1/Ltn1 has been implicated in the proteasomal degradation of soluble cytosolic nonstop and translationally stalled proteins. Rkr1 is essential for cellular fitness under conditions associated with increased prevalence of nonstop proteins. Mutation of the mammalian homolog causes significant neurological pathology, suggesting broad physiological significance of ribosome-associated quality control. It is not known whether and how soluble or transmembrane nonstop and translationally stalled proteins targeted to the endoplasmic reticulum (ER) are detected and degraded. We generated and characterized model soluble and transmembrane ER-targeted nonstop and translationally stalled proteins. We found that these proteins are indeed subject to proteasomal degradation. We tested three candidate ubiquitin ligases (Rkr1 and ER-associated Doa10 and Hrd1) for roles in regulating abundance of these proteins. Our results indicate that Rkr1 plays the primary role in targeting the tested model ER-targeted nonstop and translationally stalled proteins for degradation. These data expand the catalog of Rkr1 substrates and highlight a previously unappreciated role for this ubiquitin ligase at the ER membrane.
Collapse
Affiliation(s)
- Justin J Crowder
- From the Department of Biology, Ball State University, Muncie, Indiana 47306 and
| | - Marco Geigges
- the Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Ryan T Gibson
- From the Department of Biology, Ball State University, Muncie, Indiana 47306 and
| | - Eric S Fults
- From the Department of Biology, Ball State University, Muncie, Indiana 47306 and
| | - Bryce W Buchanan
- From the Department of Biology, Ball State University, Muncie, Indiana 47306 and
| | - Nadine Sachs
- the Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Andrea Schink
- the Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Stefan G Kreft
- the Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Eric M Rubenstein
- From the Department of Biology, Ball State University, Muncie, Indiana 47306 and
| |
Collapse
|