ER stress-unfolded protein response (UPRer) (Caenorhabditis elegans)
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Description
Correctly folding proteins is a severely complicated process that fails at times, despite the controlled environment of the ER and numerous molecular helpers. Under normal conditions, these misfolded proteins are degraded through the ER-associated degradation (ERAD) mechanism. However, various physiological or environmental stressors can inhibit or overwhelm these normal mechanisms resulting in an increase in the amount of misfolded proteins, which trigger the Unfolded Protein Response (UPR). Organisms have evolved the UPR to handle this ER stress and suppress the toxicity of accumulated misfolded proteins (proteotoxicity). In mammals the UPR attenuates protein synthesis through PERK/PEK1 and increases transcription of folding and ERAD components through activation of potent transcription factors through IRE1 splicing of XBP1 mRNA and ER-stress cleavage of ATF-6. These events ultimately augment folding and enhance degradation capacity of the organelle. In C. elegans, the UPR also activates transcriptional regulators that reduce protein synthesis and increase the number of components necessary to deal with misfolded proteins.
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Bibliography
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- Shen X, Ellis RE, Sakaki K, Kaufman RJ; ''Genetic interactions due to constitutive and inducible gene regulation mediated by the unfolded protein response in C. elegans.''; PLoS Genet, 2005 PubMed Europe PMC Scholia
- Calfon M, Zeng H, Urano F, Till JH, Hubbard SR, Harding HP, Clark SG, Ron D; ''IRE1 couples endoplasmic reticulum load to secretory capacity by processing the XBP-1 mRNA.''; Nature, 2002 PubMed Europe PMC Scholia
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- Dejima K, Murata D, Mizuguchi S, Nomura KH, Gengyo-Ando K, Mitani S, Kamiyama S, Nishihara S, Nomura K; ''The ortholog of human solute carrier family 35 member B1 (UDP-galactose transporter-related protein 1)is involved in maintenance of ER homeostasis and essential for larval development in Caenorhabditis elegans.''; FASEB J, 2009 PubMed Europe PMC Scholia
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History
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External references
DataNodes
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Name | Type | Database reference | Comment |
---|---|---|---|
ABU-1 | GeneProduct | AC3.3 (WormBase) | |
APY-1 | GeneProduct | WBGene00017244 (Ensembl) | |
ATF-6 bZip domain | GeneProduct | WBGene00000222 (Ensembl) | UPR transducer. Few genes depend on ATF-6 induction in response to ER-stress. |
ATF-6 | GeneProduct | WBGene00000222 (Ensembl) | UPR transducer. Few genes depend on ATF-6 induction in response to ER-stress. |
BiP/ GRP78 | Protein | Although not directly shown in C. elegans, BiP/GRP78 (HSP-3 or HSP-4 in C. elegans) has been shown to bind to IRE-1 in its monomeric state in other organisms. Unfolded proteins are thought to compete with IRE-1 for binding to BiP/GRP78 such that an increased load of unfolded proteins would cause dissociation of BiP/GRP78 from IRE-1, thereby allowing IRE-1 dimerization and subsequent activation of XBP-1. | |
CRT-1 | GeneProduct | WBGene00000802 (Ensembl) | |
Development | Pathway | ||
ER homeostasis | Pathway | ||
ERAD Pathway | Pathway | WP2591 (WikiPathways) | |
HSP-3/ BiP/GRP78 | GeneProduct | WBGene00002007 (Ensembl) | |
HSP-4/ BiP/GRP78 | Protein | WBGene00002008 (Ensembl) | |
HUT-1 | GeneProduct | WBGene00013740 (Ensembl) | HUT-1 is a UDP-Galactose transporter required for normal ER homeostasis |
IRE-1 | GeneProduct | WBGene00002147 (Ensembl) | UPR transducer |
PEK-1 | GeneProduct | WBGene00003970 (Ensembl) | UPR-transducer |
S2PProtease | GeneProduct | WBGene00013225 (Ensembl) | |
Translation | Pathway | ||
UGGT-1 | Protein | WBGene00018604 (Ensembl) | |
UGGT-2 | Protein | WBGene00009178 (Ensembl) | |
XBP-1 | GeneProduct | WBGene00006959 (Ensembl) | |
apy-1 | GeneProduct | WBGene00017244 (Ensembl) | |
cht-1 | GeneProduct | WBGene00000503 (Ensembl) | |
crt-1 | GeneProduct | WBGene00000802 (Ensembl) | |
eIF2alpha | GeneProduct | WBGene00021351 (Ensembl) | |
hsp-4 | GeneProduct | WBGene00002008 (Ensembl) | |
tunicamycin | Metabolite | CHEBI:29699 (ChEBI) | |
uggt-1 | GeneProduct | WBGene00018604 (Ensembl) | |
uggt-2 | GeneProduct | WBGene00009178 (Ensembl) | |
xbp-1 mRNA | GeneProduct | WBGene00006959 (Ensembl) |
Annotated Interactions
No annotated interactions