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Cho, JinAh

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Cho, JinAh
Author's Publications: search.filters.isAuthorOfPublication.538220fe-65c7-4765-8803-5a4c8ba79aab

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    TorsinA participates in endoplasmic reticulum-associated degradation
    (Nature Publishing Group, 2012) Nery, Flávia C.; Armata, Ioanna A.; Farley, Jonathan E.; Cho, JinAh; Yaqub, Uzma; Chen, Pan; da Hora, Cintia Carla; Wang, Qiuyan; Tagaya, Mitsuo; Klein, Christine; Tannous, Bakhos; Caldwell, Kim A.; Caldwell, Guy A.; Lencer, Wayne; Ye, Yihong; Breakefield, Xandra
    TorsinA is an \(AAA^+\) ATPase located within the lumen of the endoplasmic reticulum and nuclear envelope, with a mutant form causing early onset torsion dystonia (DYT1). Here we report a new function for torsinA in endoplasmic reticulum-associated degradation (ERAD). Retro-translocation and proteosomal degradation of a mutant cystic fibrosis transmembrane conductance regulator \((CFTR\Delta F508)\) was inhibited by downregulation of torsinA or overexpression of mutant torsinA, and facilitated by increased torsinA. Retro-translocation of cholera toxin was also decreased by downregulation of torsinA. TorsinA associates with proteins implicated in ERAD, including Derlin-1, VIMP, and p97. Further, torsinA reduces endoplasmic reticulum stress in nematodes overexpressing \(CFTR\Delta F508\), and fibroblasts from DYT1 dystonia patients are more sensitive than controls to endoplasmic reticulum stress and less able to degrade mutant CFTR. Therefore, compromised ERAD function in the cells of DYT1 patients may increase sensitivity to endoplasmic reticulum stress with consequent alterations in neuronal function contributing to the disease state.
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    Insights on the trafficking and retro-translocation of glycosphingolipid-binding bacterial toxins
    (Frontiers Media S.A., 2012) Cho, JinAh; Chinnapen, Daniel; Aamar, Emil; te Welscher, Yvonne Maria; Lencer, Wayne; Massol, Ramiro
    Some bacterial toxins and viruses have evolved the capacity to bind mammalian glycosphingolipids to gain access to the cell interior, where they can co-opt the endogenous mechanisms of cellular trafficking and protein translocation machinery to cause toxicity. Cholera toxin (CT) is one of the best-studied examples, and is the virulence factor responsible for massive secretory diarrhea seen in cholera. CT enters host cells by binding to monosialotetrahexosylganglioside (GM1 gangliosides) at the plasma membrane where it is transported retrograde through the trans-Golgi network (TGN) into the endoplasmic reticulum (ER). In the ER, a portion of CT, the CT-A1 polypeptide, is unfolded and then “retro-translocated” to the cytosol by hijacking components of the ER associated degradation pathway (ERAD) for misfolded proteins. CT-A1 rapidly refolds in the cytosol, thus avoiding degradation by the proteasome and inducing toxicity. Here, we highlight recent advances in our understanding of how the bacterial AB5 toxins induce disease. We highlight the molecular mechanisms by which these toxins use glycosphingolipid to traffic within cells, with special attention to how the cell senses and sorts the lipid receptors. We also discuss several new studies that address the mechanisms of toxin unfolding in the ER and the mechanisms of CT A1-chain retro-translocation to the cytosol.