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, Lee K, Liu CY, Yang K, Solomon A, Yoshida H, Morimoto R, Kurnit DM, Mori K, Kaufman RJ; ''Complementary signaling pathways regulate the unfolded protein response and are required for C. elegans development.''; Cell, 2001 PubMed Europe PMC Scholia
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- Mori K; ''Signalling pathways in the unfolded protein response: development from yeast to mammals.''; J Biochem, 2009 PubMed Europe PMC Scholia
- 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
- Buzzi LI, Simonetta SH, Parodi AJ, Castro OA; ''The two Caenorhabditis elegans UDP-glucose:glycoprotein glucosyltransferase homologues have distinct biological functions.''; PLoS One, 2011 PubMed Europe PMC Scholia
- Kapulkin WJ, Hiester BG, Link CD; ''Compensatory regulation among ER chaperones in C. elegans.''; FEBS Lett, 2005 PubMed Europe PMC Scholia
- Sood R, Porter AC, Ma K, Quilliam LA, Wek RC; ''Pancreatic eukaryotic initiation factor-2alpha kinase (PEK) homologues in humans, Drosophila melanogaster and Caenorhabditis elegans that mediate translational control in response to endoplasmic reticulum stress.''; Biochem J, 2000 PubMed Europe PMC Scholia
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 | F08C6.6 (WormBase) | |
ATF-6 bZip domain | GeneProduct | F45E6.2 (WormBase) | UPR transducer. Few genes depend on ATF-6 induction in response to ER-stress. |
ATF-6 | GeneProduct | F45E6.2 (WormBase) | 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 PEK-1 in its monomeric state in other organisms. Unfolded proteins are thought to compete with PEK-1 for binding to BiP/GRP78 such that an increased load of unfolded proteins would cause dissociation of BiP/GRP78 from PEK-1, thereby allowing PEK-1 dimerization and subsequent activation of XBP-1. | |
CRT-1 | GeneProduct | Y38A10A.5 (WormBase) | |
Development | Pathway | ||
ER homeostasis | Pathway | ||
ERAD Pathway | Pathway | ||
HSP-3/ BiP | GeneProduct | C15H9.6 (WormBase) | |
HSP-4/ BiP | GeneProduct | F43E2.8 (WormBase) | |
HUT-1 | GeneProduct | Y111B2A.20 (WormBase) | HUT-1 is a UDP-Galactose transporter required for normal ER homeostasis |
IRE-1 | GeneProduct | C41C4.4 (WormBase) | UPR transducer |
PEK-1 | GeneProduct | F46C3.1 (WormBase) | UPR-transducer |
Translation | Pathway | ||
UGGT-1 | Protein | F48E3.3 (WormBase) | |
UGGT-2 | Protein | F26H9.8 (WormBase) | |
XBP-1 | GeneProduct | R74.3 (WormBase) | |
Y56A3A.2 (S2P Protease) | Protein | Y56A3A.2 (Ensembl) | |
apy-1 | GeneProduct | F08C6.6 (WormBase) | |
cht-1 | GeneProduct | C04F6.3 (WormBase) | |
crt-1 | GeneProduct | Y38A10A.5 (WormBase) | |
eIF2alpha | Protein | Y37E3.10 (Ensembl) | |
eIF2alpha | Protein | Y37E3.10 (WormBase) | |
hsp-4 | GeneProduct | F43E2.8 (WormBase) | |
tunicamycin | Metabolite | CHEBI:29699 (ChEBI) | |
uggt-1 | GeneProduct | F48E3.3 (WormBase) | |
uggt-2 | GeneProduct | F26H9.8 (WormBase) |
Annotated Interactions
No annotated interactions