Cell Damage in Light Chain Amyloidosis: FIBRIL INTERNALIZATION, TOXICITY AND CELL-MEDIATED SEEDING

• Published in: The Journal of biological chemistry Vol. 291; no. 38; pp. 19813 - 19825
• Main Authors: Marin-Argany, Marta, Lin, Yi, Misra, Pinaki, Williams, Angela, Wall, Jonathan S, Howell, Kyle G, Elsbernd, Laura R, McClure, Megan, Ramirez-Alvarado, Marina
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 16-09-2016
• Subjects: Amyloid - genetics; Amyloid - metabolism; Amyloidosis - genetics; Amyloidosis - metabolism; Cell Survival; Humans; Immunoglobulin Light Chains - genetics; Immunoglobulin Light Chains - metabolism; Molecular Bases of Disease; Pinocytosis; Protein Aggregation, Pathological - genetics; Protein Aggregation, Pathological - metabolism; cardiomyocytes; toxicity; in vivo imaging; amyloid; cell internalization; protein aggregation; apoptosis; endocytosis; light chain amyloidosis; fibril fragmentation
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M116.736736

Light chain (AL) amyloidosis is an incurable human disease characterized by the misfolding, aggregation, and systemic deposition of amyloid composed of immunoglobulin light chains (LC). This work describes our studies on potential mechanisms of AL cytotoxicity. We have studied the internalization of AL soluble proteins and amyloid fibrils into human AC16 cardiomyocytes by using real time live cell image analysis. Our results show how external amyloid aggregates rapidly surround the cells and act as a recruitment point for soluble protein, triggering the amyloid fibril elongation. Soluble protein and external aggregates are internalized into AC16 cells via macropinocytosis. AL amyloid fibrils are shown to be highly cytotoxic at low concentrations. Additionally, caspase assays revealed soluble protein induces apoptosis, demonstrating different cytotoxic mechanisms between soluble protein and amyloid aggregates. This study emphasizes the complex immunoglobulin light chain-cell interactions that result in fibril internalization, protein recruitment, and cytotoxicity that may occur in AL amyloidosis.