Dong, Xiaolin, Svantesson, Teodor, Sholts, Sabrina B., Wallin, Cecilia, Jarvet, Juri, Graslund, Astrid, and Warmlander, Sebastian K. T. S. 2019. "Copper ions induce dityrosine-linked dimers in human but not in murine islet amyloid polypeptide (IAPP/amylin)." Biochemical and biophysical research communications, 510, (4) 520–524. https://doi.org/10.1016/j.bbrc.2019.01.120.
Dysregulation and aggregation of the peptide hormone IAPP (islet amyloid polypeptide, a.k.a. amylin) into soluble oligomers that appear to be cell-toxic is a known aspect of diabetes mellitus (DM) Type 2 pathology. IAPP aggregation is influenced by several factors including interactions with metal ions such as Cu(II). Because Cu(II) ions are redox-active they may contribute to metal-catalyzed formation of oxidative tyrosyl radicals, which can generate dityrosine cross-links. Here, we show that such a process, which involves Cu(II) ions bound to the IAPP peptide together with H2O2, can induce formation of large amounts of IAPP dimers connected by covalent dityrosine cross-links. This cross-linking is less pronounced at low pH and for murine IAPP, likely due to less efficient Cu(II) binding. Whether IAPP can carry out its hormonal function as a cross-linked dimer is unknown. As dityrosine concentrations are higher in blood plasma of DM Type 2 patients - arguably due to disease-related oxidative stress - and as dimer formation is the first step in protein aggregation, generation of dityrosine-linked dimers may be an important factor in IAPP aggregation and thus relevant for DM Type 2 progression. (C) 2019 Elsevier Inc. All rights reserved.
