TY - JOUR
T1 - Structural studies and cytotoxicity assays of “aggregation-prone” IAPP8–16 and its non-amyloidogenic variants suggest its important role in fibrillogenesis and cytotoxicity of human amylin
AU - Louros, Nikolaos N.
AU - Tsiolaki, Paraskevi L.
AU - Zompra, Aikaterini A.
AU - Pappa, Eleni V.
AU - Magafa, Vassiliki
AU - Pairas, George
AU - Cordopatis, Paul
AU - Cheimonidou, Christina
AU - Trougakos, Ioannis P.
AU - Iconomidou, Vassiliki A.
AU - Hamodrakas, Stavros J.
N1 - Publisher Copyright:
© 2015 Wiley Periodicals, Inc.
PY - 2015/5/1
Y1 - 2015/5/1
N2 - Amyloid deposits to the islets of Langerhans are responsible for the gradual loss of pancreatic β-cells leading to type II diabetes mellitus. Human mature islet amyloid polypeptide (hIAPP), a 37-residue pancreatic hormone, has been identified as the primary component of amyloid fibrils forming these deposits. Several individual segments along the entire sequence length of hIAPP have been nominated as regions with increased amyloidogenic potential, such as regions 8–20, 20–29, and 30–37. A smaller fragment of the 8–20 region, spanning residues 8–16 of hIAPP has been associated with the formation of early transient α-helical dimers that promote fibrillogenesis and also as a core part of hIAPP amyloid fibrils. Utilizing our aggregation propensity prediction tools AmylPred and AmylPred2, we have identified the high aggregation propensity of the 8–16 segment of hIAPP. A peptide analog corresponding to this segment was chemically synthesized and its amyloidogenic properties were validated using electron microscopy, X-ray fiber diffraction, ATR FT-IR spectroscopy, and polarized microscopy. Additionally, two peptides introducing point mutations L12R and L12P, respectively, to the 8–16 segment, were chemically synthesized. Both mutations disrupt the α-helical properties of the 8–16 region and lower its amyloidogenic potential, which was confirmed experimentally. Finally, cytotoxicity assays indicate that the 8–16 segment of hIAPP shows enhanced cytotoxicity, which is relieved by the L12R mutation but not by the L12P mutation. Our results indicate that the chameleon properties and the high aggregation propensity of the 8–16 region may significantly contribute to the formation of amyloid fibrils and the overall cytotoxic effect of hIAPP.
AB - Amyloid deposits to the islets of Langerhans are responsible for the gradual loss of pancreatic β-cells leading to type II diabetes mellitus. Human mature islet amyloid polypeptide (hIAPP), a 37-residue pancreatic hormone, has been identified as the primary component of amyloid fibrils forming these deposits. Several individual segments along the entire sequence length of hIAPP have been nominated as regions with increased amyloidogenic potential, such as regions 8–20, 20–29, and 30–37. A smaller fragment of the 8–20 region, spanning residues 8–16 of hIAPP has been associated with the formation of early transient α-helical dimers that promote fibrillogenesis and also as a core part of hIAPP amyloid fibrils. Utilizing our aggregation propensity prediction tools AmylPred and AmylPred2, we have identified the high aggregation propensity of the 8–16 segment of hIAPP. A peptide analog corresponding to this segment was chemically synthesized and its amyloidogenic properties were validated using electron microscopy, X-ray fiber diffraction, ATR FT-IR spectroscopy, and polarized microscopy. Additionally, two peptides introducing point mutations L12R and L12P, respectively, to the 8–16 segment, were chemically synthesized. Both mutations disrupt the α-helical properties of the 8–16 region and lower its amyloidogenic potential, which was confirmed experimentally. Finally, cytotoxicity assays indicate that the 8–16 segment of hIAPP shows enhanced cytotoxicity, which is relieved by the L12R mutation but not by the L12P mutation. Our results indicate that the chameleon properties and the high aggregation propensity of the 8–16 region may significantly contribute to the formation of amyloid fibrils and the overall cytotoxic effect of hIAPP.
KW - amylin
KW - amyloid fibrils
KW - cytotoxicity assays
KW - islet amyloid polypeptide (IAPP)
KW - peptide analogs
KW - type II diabetes mellitus
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U2 - 10.1002/bip.22650
DO - 10.1002/bip.22650
M3 - Article
C2 - 25913357
AN - SCOPUS:84980017959
SN - 0006-3525
VL - 104
SP - 196
EP - 205
JO - Biopolymers
JF - Biopolymers
IS - 3
ER -