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Systemic misfolding of immunoglobulins in the test tube and in the cell
Author(s) -
RamirezAlvarado Marina,
Dick Christopher J.,
BlancasMejia Luis M.,
Misra Pinaki,
Lin Yi,
Redhage Keely R.,
Jordan Torri L.,
Williams Angela,
Wall Jonathan S.
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.247.3
Subject(s) - fibril , amyloid (mycology) , chemistry , immunoglobulin light chain , biophysics , amyloidosis , protein aggregation , extracellular matrix , amyloid disease , microbiology and biotechnology , antibody , biochemistry , amyloid fibril , biology , immunology , amyloid β , medicine , inorganic chemistry , disease , pathology
Light chain (AL) amyloidosis is an incurable disease characterized by the misfolding, aggregation, and systemic deposition of amyloid composed of immunoglobulin light chains causing organ failure and death. We have conducted thermodynamic and fibril formation studies of both variable domain and full length (variable + constant domains) immunoglobulin proteins involved in AL amyloidosis. We have found that there is thermodynamic range ‐under physiological conditions‐ in which these proteins populate partially folded states that favor amyloid formation. Scan rate dependency in the protein unfolding reaction plays a role for a subset of these proteins, particularly full length light chains. Immunoglobulin light chains internalize as dimers and as amyloid fibrils into human cardiomyocytes via micropinocytosis in a size dependent manner. External amyloid aggregates rapidly surround the cells and act as a recruitment point for soluble protein, triggering amyloid fibril elongation. Light chain dimers cause apoptosis while amyloid fibrils cause cell growth arrest demonstrating different cytotoxic mechanisms for soluble proteins and amyloid aggregates. The cell growth arrest observed in the presence of amyloid fibrils is rescued by cell to cell contacts with mesenchymal stromal stem cells through changes in the extracellular matrix and cell adhesion pathways. In vitro amyloid formation experiments show that seeds of proteins with different sequences are able to accelerate the reaction albeit with a lower efficiency. Heterologous recruitment of light chains indicate that fibril formation is kinetically determined by the conformation of the amyloidogenic conformational precursor and modulated by the differential ability of each protein to either nucleate or elongate fibrils. Studies on the early events of fibril formation followed by different biophysical techniques have shown differences in the species formed by fast amyloid forming protein AL‐09 compared to slow amyloid forming (AL‐12) and control (kI) proteins indicating that the rate of formation of intermediates may vary depending on the amyloidogenic potential of the proteins. Overall, our studies emphasize the complex interactions between light chain and cells that result in fibril internalization, protein recruitment, and cytotoxicity that may occur in AL amyloidosis. Support or Funding Information NIGMS R01 GM071514, theSeidler Professorship, the Mayo Foundation, and thegenerous support of amyloidosis patients and their familiesExternal LC amyloid fibrils act as a seeding point for soluble protein.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .