title: Role of endocytic inhibitory drugs on internalization of amyloidogenic light chains by cardiac fibroblasts.
abstract: Amyloidosis is a disease of protein misfolding that ultimately impairs organ function. Previously, we demonstrated that amyloidogenic light chains (kappa1, lambda6, and lambda3 subtypes), internalized by cardiac fibroblasts, enhanced sulfation of secreted glycosaminoglycans. In this study, we investigated the internalization and cellular trafficking of urinary immunoglobulin light chains into cardiac fibroblasts. We demonstrate that these light chains have the ability to form annular rings in solution. Internalization was assessed by incubating cells in the presence of light chain conjugated to Oregon Green 488 followed by monitoring with live cell confocal imaging. The rate of light chain internalization was reduced by treatment with methyl-beta-cyclodextrin but not filipin. Amyloid light chain did co-localize with dextran-Texas Red. Once internalized, the light chains were detected in lysosomes and then secreted into the extracellular medium. The light chain detected in the cell lysate and medium possessed a lower hydrophobic species. Nocodazole, a microtubule inhibitor, did not disperse aggregates. In addition, internalization and retention of the light chain proteins was altered in the presence of the proteasomal inhibitor MG132. These results indicate that the cell internalizes light chain by a fluid phase endocytosis, which is then modified and ultimately compromises the cell.
authors.affiliation: Department of Pathology, Gerry Amyloid Research Laboratory, Boston University School of Medicine, 80 E. Concord St. L904, Boston, MA 02118, USA.
authors.forename: Grace Fortes
authors.initials: GF
authors.lastname: Monis
authors.forename: Christopher
authors.initials: C
authors.lastname: Schultz
authors.forename: Ruiyi
authors.initials: R
authors.lastname: Ren
authors.forename: Jeremy
authors.initials: J
authors.lastname: Eberhard
authors.forename: Catherine
authors.initials: C
authors.lastname: Costello
authors.forename: Lawreen
authors.initials: L
authors.lastname: Connors
authors.forename: Martha
authors.initials: M
authors.lastname: Skinner
authors.forename: Vickery
authors.initials: V
authors.lastname: Trinkaus-Randall
mesh_terms: D000682:Amyloid / Q000378:metabolism*; D000686:Amyloidosis / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003911:Dextrans / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects*; D005347:Fibroblasts / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D007147:Immunoglobulin Light Chains / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D051381:Rats
chemical_list: D000682:Amyloid; D003911:Dextrans; D007147:Immunoglobulin Light Chains