The overall goal of our proposed research is to dissect the molecular mechanisms that cause Light chain amyloidosis (AL) deposits to form. AL is a devastating disease caused by the abnormal proliferation of plasma B cells. These tumor cells secrete monoclonal immunoglobulin light chains that misfold as truncated light chains into amyloid deposits in vital organs, causing tissue damage and organ failure. Somatic mutations that accumulate in the immunoglobulin variable domain make these proteins less thermodynamially stable than their non-amyloidogenic counterparts. Both immunoglobulin light and heavy chains are produced in the mature plasma B cell where they associate to form antibodies that are secreted into circulation. In most AL patients, only light chain is secreted into circulation, even when the heavy chain is present in the plasma cell, suggesting a failure to associate with the heavy chain. Many questions remain unanswered in regards to AL. It is not clear what causes the loss of association with the heavy chain, the cellular compartment or event that leads to the truncation of the protein, and whether or not the truncation is an important destabilzing event that triggers amyloid formation. Finally, given the rich mutational diversity of AL, no comprehensive study has been done to understand the role of the location of mutations in protein folding, stability and amyloidogenicity in AL. We hypothesize that AL protein destabilization is due to sampling of partially unfolded states triggered by one or more of the following events: somatic mutations, dissociation from the immunoglobulin heavy chain, and/or proteolytic cleavage.
Aim 1 of this work will study the structure and stability of variable domain, truncated and full length AL proteins. We will also perform a systematic restoration of AL mutations to germline residues to identify the mutations responsible for the propensity to form amyloid.
Aim 2 will characterize amyloid formation by AL proteins. We will study the role of sodium sulfate stabilizing amyloidogenic intermediates and accelerating amyloid formation.
Aim 3 will study the cell biology of AL. We will determine the integrity of the HC gene, the ability of AL proteins to dimerize with heavy chains and will study internalization of light chains in cell culture to determine if intracellular proteolysis is occurring. This work will increase our understanding of the mechanism of AL pathogenesis, helping us delineate better strategies for its management and cure. ? ? ?

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Special Emphasis Panel (ZRG1-CDIN-D (01))
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Wehrle, Janna P
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Mayo Clinic, Rochester
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Blancas-Mejia, Luis M; Misra, Pinaki; Dick, Christopher J et al. (2018) Immunoglobulin light chain amyloid aggregation. Chem Commun (Camb) 54:10664-10674
Blancas-Mejía, Luis M; Misra, Pinaki; Ramirez-Alvarado, Marina (2017) Differences in Protein Concentration Dependence for Nucleation and Elongation in Light Chain Amyloid Formation. Biochemistry 56:757-766
Blancas-Mejía, Luis M; Martin, Emily B; Williams, Angela et al. (2017) Kinetic stability and sequence/structure studies of urine-derived Bence-Jones proteins from multiple myeloma and light chain amyloidosis patients. Biophys Chem 230:89-98
Piehl, Dennis W; Blancas-Mejía, Luis M; Ramirez-Alvarado, Marina et al. (2017) Solid-state NMR chemical shift assignments for AL-09 VL immunoglobulin light chain fibrils. Biomol NMR Assign 11:45-50
Lin, Yi; Marin-Argany, Marta; Dick, Christopher J et al. (2017) Mesenchymal stromal cells protect human cardiomyocytes from amyloid fibril damage. Cytotherapy 19:1426-1437
Marin-Argany, Marta; Lin, Yi; Misra, Pinaki et al. (2016) Cell Damage in Light Chain Amyloidosis: FIBRIL INTERNALIZATION, TOXICITY AND CELL-MEDIATED SEEDING. J Biol Chem 291:19813-25
Blancas-Mejía, Luis M; Ramirez-Alvarado, Marina (2016) Recruitment of Light Chains by Homologous and Heterologous Fibrils Shows Distinctive Kinetic and Conformational Specificity. Biochemistry 55:2967-78
Franco, Daniel A; Truran, Seth; Weissig, Volkmar et al. (2016) Monosialoganglioside-Containing Nanoliposomes Restore Endothelial Function Impaired by AL Amyloidosis Light Chain Proteins. J Am Heart Assoc 5:
Blancas-Mejía, Luis M; Horn, Timothy J; Marin-Argany, Marta et al. (2015) Thermodynamic and fibril formation studies of full length immunoglobulin light chain AL-09 and its germline protein using scan rate dependent thermal unfolding. Biophys Chem 207:13-20
Blancas-Mejía, Luis M; Hammernik, Jared; Marin-Argany, Marta et al. (2015) Differential effects on light chain amyloid formation depend on mutations and type of glycosaminoglycans. J Biol Chem 290:4953-65

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