Studies on the familial forms of systemic amyloidosis are aimed at understanding the pathogenetic mechanism by which normally soluble proteins form insoluble amyloid fibrils and extracellular tissue deposits. Amyloidogenic proteins being investigated include transthyretin (TTR), apolipoprotein AI and AII, lysozyme, fibrinogen (alpha chain) and gelsolin.
At present, much of the research is focused on identifying specific age-related, structural features present in TTR that may be important in cardiac forms of inherited or senile systemic amyloidosis. This work attempts to link protein biochemistry to disease pathology by studying the role of amino acid alterations, post-translational modifications (glycosylation, sulfonation, cysteinylation and phosphorylation) and metabolic processing in amyloid fibril formation. Specifically, our aims are to precisely define the molecular composition and interactions of TTR in amyloid disease. Using mass spectrometry and electron microscopy, we are characterizing TTR in patient serum and tissue samples, identifying other major fibril components and studying the ultrastructure of purified TTR and its heteroassociation with other deposited molecular constituents.
In addition, the roles of certain molecular effectors and inhibitors of TTR aggregation and fibril formation are being studied. More specifically, the effect of environmental parameters (pH, divalent cations, temperature), accessory molecules (heparan sulfate, serum amyloid P) and small molecule inhibitors (diflunisal, α-tocopherol) on TTR subunit association, aggregation rate and fibril formation is being investigated by electrophoretic, chromatographic and histological methods. We are also interested in defining the direct and indirect effects of amyloidogenic TTR proteins on cardiac myocytes. Cells treated with amyloidogenic forms of TTR are studied to determine alterations in myocyte oxidative stress, calcium handling or contractility, myocyte growth or survival, and endothelial cell/myocyte paracrine signaling.