title: ER storage diseases: a role for ERGIC-53 in controlling the formation and shape of Russell bodies.
abstract: Owing to the impossibility of reaching the Golgi for secretion or the cytosol for degradation, mutant Ig-mu chains that lack the first constant domain (muDeltaCH1) accumulate as detergent-insoluble aggregates in dilated endoplasmic reticulum cisternae, called Russell bodies. The presence of similar structures hallmarks many ER storage diseases, but their pathogenic role(s) remain obscure. Exploiting inducible cellular systems, we show here that Russell bodies form when the synthesis of muDeltaCH1 exceeds the degradation capacity. Condensation occurs in different sub-cellular locations, depending on the interacting molecules present in the host cell: if Ig light chains are co-expressed, detergent-insoluble muDeltaCH1-light chain oligomers accumulate in large ribosome-coated structures (rough Russell bodies). In absence of light chains, instead, aggregation occurs in smooth tubular vesicles and is controlled by N-glycan-dependent interactions with ER-Golgi intermediate compartment 53 (ERGIC-53). In cells containing smooth Russell bodies, ERGIC-53 co-localizes with muDeltaCH1 aggregates in a Ca2+ -dependent fashion. Our findings identify a novel ERGIC-53 substrate, and indicate that interactions with light chains or ERGIC-53 seed muDeltaCH1 condensation in different stations of the early secretory pathway.
authors.affiliation: MicroSCoBiO Research Center and IFOM Center of Cell Oncology and Ultrastructure, Department of Experimental Medicine, University of Genova, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Mattioli
authors.forename: Tiziana
authors.initials: T
authors.lastname: Anelli
authors.forename: Claudio
authors.initials: C
authors.lastname: Fagioli
authors.forename: Carlo
authors.initials: C
authors.lastname: Tacchetti
authors.forename: Roberto
authors.initials: R
authors.lastname: Sitia
authors.forename: Caterina
authors.initials: C
authors.lastname: Valetti
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000473:pathology; D006367:HeLa Cells; D006801:Humans; D007148:Immunoglobulin mu-Chains / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D008358:Mannose / Q000037:antagonists & inhibitors / Q000378:metabolism; D037241:Mannose-Binding Lectins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008661:Metabolism, Inborn Errors / Q000378:metabolism* / Q000473:pathology; D017510:Protein Folding
chemical_list: D000470:Alkaloids; D007148:Immunoglobulin mu-Chains; C084004:LMAN1 protein, human; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; C065629:kifunensine; D008358:Mannose; D002118:Calcium