Probing ion channel activity of human islet amyloid polypeptide (amylin)

Jun Zhao, Yin Luo, Hyunbum Jang, Xiang Yu, Guanghong Wei, Ruth Nussinov, Jie Zheng

Research output: Contribution to journalArticlepeer-review

Abstract

Interactions of human islet amyloid polypeptide (hIAPP or amylin) with the cell membrane are correlated with the dysfunction and death of pancreatic islet β-cells in type II diabetes. Formation of receptor-independent channels by hIAPP in the membrane is regarded as one of the membrane-damaging mechanisms that induce ion homeostasis and toxicity in islet β-cells. Here, we investigate the dynamic structure, ion conductivity, and membrane interactions of hIAPP channels in the DOPC bilayer using molecular modeling and molecular dynamics simulations. We use the NMR-derived β-strand-turn-β-strand motif as a building block to computationally construct a series of annular-like hIAPP structures with different sizes and topologies. In the simulated lipid environments, the channels lose their initial continuous β-sheet network and break into oligomeric subunits, which are still loosely associated to form heterogeneous channel conformations. The channels' shapes, morphologies and dimensions are compatible with the doughnut-like images obtained by atomic force microscopy, and with those of modeled channels for Aβ, the β2-microglobulin-derived K3 peptides, and the β-hairpin-based channels of antimicrobial peptide PG-1. Further, all channels induce directional permeability of multiple ions across the bilayers from the lower to the upper leaflet. This similarity suggests that loosely-associated β-structure motifs can be a general feature of toxic, unregulated channels. In the absence of experimental high-resolution atomic structures of hIAPP channels in the membrane, this study represents a first attempt to delineate some of the main structural features of the hIAPP channels, for a better understanding of the origin of amyloid toxicity and the development of pharmaceutical agents.

Original languageEnglish
Pages (from-to)3121-3130
Number of pages10
JournalBiochimica et Biophysica Acta - Biomembranes
Volume1818
Issue number12
DOIs
StatePublished - Dec 2012

Keywords

  • Directional permeability
  • Ion channel
  • Molecular dynamic
  • hIAPP

Fingerprint

Dive into the research topics of 'Probing ion channel activity of human islet amyloid polypeptide (amylin)'. Together they form a unique fingerprint.

Cite this