Using TTR50‐127 fragments as probes to detect amyloidogenic seeding

Abstract

The aggregation and amyloid deposition of soluble transthyretin (TTR) has been linked to the development sporadic and familial forms of cardiac amyloidosis. TTR associated cardiomyopathies are often diagnosed when the disease state has reached advanced stages (if at all), precluding effective clinical intervention. This diagnostic problem can largely be attributed to a lack of fundamental understanding of the mechanism of disease pathogenesis and the clinical similarities of TTR cardiomyopathies to other heart failure related conditions. In the human prion diseases and tau protein related neurodegenerative diseases, the amyloidogenic protein conformations have the ability to “seed” and transform non‐amyloidogenic states into pathogenic amyloid‐like states. Therefore, we hypothesized that TTR related cardiomyopathies may undergo similar seed based aggregation mechanisms. To test this hypothesis, we synthesized C‐terminal fragments of Transthyretin that are fluorescently labeled and upon assembly, the fluorescent signal is quenched and provides a convenient method to measure aggregation. We specifically chose the C‐terminal peptide fragment (TTR50–127) because at autopsy it has been shown that the C‐terminal region is preferentially deposited in heart tissue compared to the full length sequence. First we used these fluorescent probes to analyze the kinetics involved in the transition from monomeric TTR to the stable polymeric form of TTR and thus demonstrated proof‐of‐principle. As C‐terminally cleaved TTR is primarily found in biopsies of cardiomyopathy patients, introduction of rhodamine labeled TTR50–127 to cardiomyopathy and polyneuropathy patient plasma revealed distinct aggregation profiles in Native PAGE gels. While preliminary in nature, these results suggest that plasma of symptomatic patients may accelerate the aggregation of Transthyretin.Support or Funding InformationSpecial thanks to staff of the Kelly Lab at TSRI as well as mentors James Smart Ph.D. and Jeff Duerr Ph.D.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.