| 1. |
- Rodrigues, Joana Isabel, et al.
(författare)
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Yeast chaperones and ubiquitin ligases contribute to proteostasis during arsenite stress by preventing or clearing protein aggregates
- 2023
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Ingår i: Febs Letters. - 0014-5793. ; 597:13, s. 1733-47
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Tidskriftsartikel (refereegranskat)abstract
- Arsenite causes proteotoxicity by targeting nascent proteins for misfolding and aggregation. Here, we assessed how selected yeast chaperones and ubiquitin ligases contribute to proteostasis during arsenite stress. Loss of the ribosome-associated chaperones Zuo1, Ssz1, and Ssb1/Ssb2 reduced global translation and protein aggregation, and increased arsenite resistance. Loss of cytosolic GimC/prefoldin function led to defective aggregate clearance and arsenite sensitivity. Arsenite did not induce ribosomal stalling or impair ribosome quality control, and ribosome-associated ubiquitin ligases contributed little to proteostasis. Instead, the cytosolic ubiquitin ligase Rsp5 was important for aggregate clearance and resistance. Our study suggests that damage prevention, by decreased aggregate formation, and damage elimination, by enhanced aggregate clearance, are important protective mechanisms that maintain proteostasis during arsenite stress.
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| 2. |
- Singla, Akshi, et al.
(författare)
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Cholera intoxication of human enteroids reveals interplay between decoy and functional glycoconjugate ligands
- 2023
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Ingår i: Glycobiology. - 1460-2423. ; 33:10, s. 801-816
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Tidskriftsartikel (refereegranskat)abstract
- Prior research on cholera toxin (CT) binding and intoxication has relied on human colonic cancer derived epithelial cells. While these transformed cell lines have been beneficial, they neither derive from small intestine where intoxication occurs, nor represent the diversity of small intestinal epithelial cells (SI-ECs) and variation in glycoconjugate expression among individuals. Here, we used human enteroids, derived from jejunal biopsies of multipledonors to study CT binding and intoxication of human non-transformed SI-ECs. We modulated surface expression of glycosphingolipids, glycoproteins and specific glycans to distinguish the role of each glycan/glycoconjugate. Cholera-toxin-subunit-B (CTB) mutants were generated to decipher the preference of each glycoconjugate to different binding sites and the correlation between CT binding and intoxication. Human enteroids contain trace amounts of GM1, but other glycosphingolipids may be contributing to CT intoxication. We discovered that inhibition of either fucosylation or O-glycosylation sensitize enteroids to CT-intoxication. This can either be a consequence of the removal of fucosylated "decoy-like-ligands" binding to CTB's non-canonical site and/or increase in the availability of Gal/GalNAc-terminating glycoconjugates binding to the canonical site. Furthermore, simultaneous inhibition of fucosylation and O-glycosylation increased the availability of additional Gal/GalNAc-terminating glycoconjugates but counteracted the sensitization in CT intoxication caused by inhibiting O-glycosylation because of reduction in fucose. This implies a dual role of fucose as a functional glycan and a decoy, the interplay of which influences CT binding and intoxication. Finally, while the results were similar for enteroids from different donors, they were not identical, pointing to a role for human genetic variation in determining sensitivity to CT.
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