The human islet polypeptide (hIAPP) or amylin is a 37-residue peptide hormone secreted by beta-cells of the islet of Langerhans in the pancreas. Unlike the rat variant of IAPP (rIAPP), human amylin is highly amyloidogenic and is found as amyloid deposits in nearly 95% of patients afflicted with type 2 diabetes mellitus (T2DM). Human and rat IAPP have nearly identical primary sequence differing at only six positions which are encompassed within the 17-29 aminoacid region. Using Circular Dichroism (CD), Dynamic Light Scattering (DLS) and ThT-fluorescence (Th-T), we examined the aggregation properties of both full-length hIAPP1-37 and the related peptide fragment hIAPP17-29. For the sake of comparison, similar experiments were carried out on the respective rat variants rIAPP1-37 and rIAPP17-29. These studies were conducted at physiological pH in buffered solution not containing fluorinated co-solvents as well as in the presence of model membranes (LUV). In addition, the cytotoxic activity of the investigated peptides was determined toward different pancreatic beta-cell lines. All the peptide studied in this work resulted cytotoxic despite beta-sheet structure being observed, in vitro, for the hIAPP1-37 only. This suggests that beta-sheet conformational transition that generally precedes the fibril formation, is not a prerequisite for toxicity towards beta-cells. Interestingly, confocal microscopy indicated that the IAPP peptides can enter the cell and might exert their toxic action at an intracellular level. (C) 2014 Elsevier Masson SAS. All rights reserved.
Molecular and cytotoxic properties of hIAPP17-29 and rIAPP17-29 fragments: A comparative study with the respective full-length parent polypeptides
Attanasio Francesco;Giuffrida Maria Laura;Campagna Tiziana;Pappalardo Giuseppe
2014
Abstract
The human islet polypeptide (hIAPP) or amylin is a 37-residue peptide hormone secreted by beta-cells of the islet of Langerhans in the pancreas. Unlike the rat variant of IAPP (rIAPP), human amylin is highly amyloidogenic and is found as amyloid deposits in nearly 95% of patients afflicted with type 2 diabetes mellitus (T2DM). Human and rat IAPP have nearly identical primary sequence differing at only six positions which are encompassed within the 17-29 aminoacid region. Using Circular Dichroism (CD), Dynamic Light Scattering (DLS) and ThT-fluorescence (Th-T), we examined the aggregation properties of both full-length hIAPP1-37 and the related peptide fragment hIAPP17-29. For the sake of comparison, similar experiments were carried out on the respective rat variants rIAPP1-37 and rIAPP17-29. These studies were conducted at physiological pH in buffered solution not containing fluorinated co-solvents as well as in the presence of model membranes (LUV). In addition, the cytotoxic activity of the investigated peptides was determined toward different pancreatic beta-cell lines. All the peptide studied in this work resulted cytotoxic despite beta-sheet structure being observed, in vitro, for the hIAPP1-37 only. This suggests that beta-sheet conformational transition that generally precedes the fibril formation, is not a prerequisite for toxicity towards beta-cells. Interestingly, confocal microscopy indicated that the IAPP peptides can enter the cell and might exert their toxic action at an intracellular level. (C) 2014 Elsevier Masson SAS. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.