TRC8-dependent degradation of hepatitis C virus immature core protein regulates viral propagation and pathogenesis

Aizawa, Sayaka; Okamoto, Tomoyoshi; Sugiyama, Yukari; Kouwaki, Takahisa; Ito, Akira; Suzuki, Tatsuya; Ono, Chikako; Fukuhara, Takasuke; Yamamoto, Masahiro; Okochi, Masayasu; Hiraga, Nobuhiko; Imamura, Michio; Chayama, Kazuaki; Suzuki, Ritsuro; Shoji, Ikuo; Moriishi, Kohji; Moriya, Kyoji; Koike, Kazuhiko; Matsuura, Yoshiharu

doi:10.1038/ncomms11379

Cited by 46 publications

(84 citation statements)

References 59 publications

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“…Following cleavage, SP is retrotranslocated into the cytosol prior to nuclear entry and binding to viral RNA (27, 32). Membrane extraction of MMTV-encoded SP is independent of cleavage by SPP or SPP-like enzymes (29), unlike other viral and cellular signal peptides (34–36). In this study, we used the UBAIT method to detect cellular proteins that associate with SP even transiently.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, Rem cleavage is required for SP function in this assay since mutations of the consensus signal peptidase recognition site prevent SP function and localization to the nucleolus (27, 29, 32, 33). SP release from microsomal membranes is independent of signal peptide peptidase (SPP) (29), which affects membrane release of some other viral signal peptides (34–36). Our previous experiments have demonstrated that uncleaved Rem is stabilized by the presence of proteasomal inhibitors, whereas cleaved SP levels are similar in the presence and in the absence of proteasome inhibitors (27).…”

Section: Introductionmentioning

confidence: 99%

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Mouse Mammary Tumor Virus Signal Peptide Uses a Novel p97-Dependent and Derlin-Independent Retrotranslocation Mechanism To Escape Proteasomal Degradation

Byun

Das

et al. 2017

mBio

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Multiple pathogens, including viruses and bacteria, manipulate endoplasmic reticulum-associated degradation (ERAD) to avoid the host immune response and promote their replication. The betaretrovirus mouse mammary tumor virus (MMTV) encodes Rem, which is a precursor protein that is cleaved into a 98-amino-acid signal peptide (SP) and a C-terminal protein (Rem-CT). SP uses retrotranslocation for ER membrane extraction and yet avoids ERAD by an unknown mechanism to enter the nucleus and function as a Rev-like protein. To determine how SP escapes ERAD, we used a ubiquitin-activated interaction trap (UBAIT) screen to trap and identify transient protein interactions with SP, including the ERAD-associated p97 ATPase, but not E3 ligases or Derlin proteins linked to retrotranslocation, polyubiquitylation, and proteasomal degradation of extracted proteins. A dominant negative p97 ATPase inhibited both Rem and SP function. Immunoprecipitation experiments indicated that Rem, but not SP, is polyubiquitylated. Using both yeast and mammalian expression systems, linkage of a ubiquitin-like domain (UbL) to SP or Rem induced degradation by the proteasome, whereas SP was stable in the absence of the UbL. ERAD-associated Derlin proteins were not required for SP activity. Together, these results suggested that Rem uses a novel p97-dependent, Derlin-independent retrotranslocation mechanism distinct from other pathogens to avoid SP ubiquitylation and proteasomal degradation.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mouse Mammary Tumor Virus Signal Peptide Uses a Novel p97-Dependent and Derlin-Independent Retrotranslocation Mechanism To Escape Proteasomal Degradation

Byun

Das

et al. 2017

mBio

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“…TRC8 binds heme oxygenase through the transmembrane region (32), and degradation is initiated by SPP cleavage in the transmembrane helix, similar to other tailanchored proteins (48). Hepatitis C virus core protein requires SPP cleavage to reach its mature form, and lack of SPP activity produces a short-lived immature form that is recognized by TRC8 (34). In these cases, the degraded proteins may be considered abnormal, and their clearance resembles protein quality control.…”

Section: Discussionmentioning

confidence: 99%

“…Second, SPP cleavage leading to TRC8 degradation requires a flexible luminal region unobstructed by glycosylation (48), whereas hERG only has short luminal loops between multiple transmembrane helices, and an N-linked glycosylation site (54). Third, all of the SPP-cleaved TRC8 substrates have single transmembrane helices so the cleaved products are released into the cytosol (33,34,48), and hERG is a tetramer of subunits with six transmembrane helices each.…”

Section: Discussionmentioning

confidence: 99%

Bag1 Co-chaperone Promotes TRC8 E3 Ligase-dependent Degradation of Misfolded Human Ether a Go-Go-related Gene (hERG) Potassium Channels

Hantouche

Williamson

Valinsky

et al. 2017

Journal of Biological Chemistry

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Edited by George N. DeMartinoCardiac long QT syndrome type 2 is caused by mutations in the human ether a go-go-related gene (hERG) potassium channel, many of which cause misfolding and degradation at the endoplasmic reticulum instead of normal trafficking to the cell surface. The Hsc70/Hsp70 chaperones assist the folding of the hERG cytosolic domains. Here, we demonstrate that the Hsp70 nucleotide exchange factor Bag1 promotes hERG degradation by the ubiquitin-proteasome system at the endoplasmic reticulum to regulate hERG levels and channel activity. Dissociation of hERG complexes containing Hsp70 and the E3 ubiquitin ligase CHIP requires the interaction of Bag1 with Hsp70, but this does not involve the Bag1 ubiquitin-like domain. The interaction with Bag1 then shifts hERG degradation to the membrane-anchored E3 ligase TRC8 and its E2-conjugating enzyme Ube2g2, as determined by siRNA screening. TRC8 interacts through the transmembrane region with hERG and decreases hERG functional expression. TRC8 also mediates degradation of the misfolded hERG-G601S disease mutant, but pharmacological stabilization of the mutant structure prevents degradation. Our results identify TRC8 as a previously unknown Hsp70-independent quality control E3 ligase for hERG.

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“…A recent study showed that in vivo inhibition of SPP by using the GSI LY-411 575 (18, Fig. 5) leads to lower expression of hepatitis C virus core particles and improves liver function in a mouse model [92]. This suggests that SPP may be used as a future drug target for treatment of hepatitis C. However, selective inhibitors may be needed in order to minimize toxicity by c-secretase inhibition.…”

Section: Selectivity Of Inhibitorsmentioning

confidence: 99%

Intramembrane proteases as drug targets

Verhelst

2017

The FEBS Journal

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Proteases are considered attractive drug targets. Various drugs targeting classical, soluble proteases have been approved for treatment of human disease. Intramembrane proteases (IMPs) are a more recently discovered group of proteolytic enzymes. They are embedded in lipid bilayers and their active sites are located in the plane of a membrane. All four mechanistic families of IMPs have been linked to disease, but currently, no drugs against IMPs have entered the market. In this review, I will outline the function of IMPs with a focus on the ones involved in human disease, which includes Alzheimer's disease, cancer, and infectious diseases by microorganisms. Inhibitors of IMPs are known for all mechanistic classes, but are not yet very potent or selective – aside from those targeting γ‐secretase. I will here describe the different features of IMP inhibitors and discuss a list of issues that need attention in the near future in order to improve the drug development for IMPs.

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TRC8-dependent degradation of hepatitis C virus immature core protein regulates viral propagation and pathogenesis

Cited by 46 publications

References 59 publications

Mouse Mammary Tumor Virus Signal Peptide Uses a Novel p97-Dependent and Derlin-Independent Retrotranslocation Mechanism To Escape Proteasomal Degradation

Mouse Mammary Tumor Virus Signal Peptide Uses a Novel p97-Dependent and Derlin-Independent Retrotranslocation Mechanism To Escape Proteasomal Degradation

Bag1 Co-chaperone Promotes TRC8 E3 Ligase-dependent Degradation of Misfolded Human Ether a Go-Go-related Gene (hERG) Potassium Channels

Intramembrane proteases as drug targets

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