ABSTRACT
The human amylin is a pancreatic peptide hormone found in hyperhormonemic state along with insulin in subclinical diabetes. Amylin has been associated with the pathology of type 2 diabetes, particularly due to its ability to assembly into toxic oligomers and amyloid specimens. On the other hand, some variants such as murine amylin has been described as non-amyloidogenic, either in vitro or in vivo. Recent data have demonstrated the amyloid propensity of murine amylin and the therapeutic analogue pramlintide, suggesting a universality for amylin amyloidosis. Here, we report the amyloidogenesis of murine amylin, which showed lower responsivity to the fluorescent probe thioflavin T compared to human amylin, but presented highly organized fibrilar amyloid material. The aggregation of murine amylin also resulted in the formation of cytotoxic specimens, as evaluated in vitro in INS-1 cells. The aggregation product from murine amylin was responsive to a specific antibody raised against amyloid oligomers, the A11 oligomer antibody. Pancreatic islets of wild-type Swiss male mice have also shown responsivity for the anti-oligomer, indicating the natural abundance of such specimen in rodents. These data provide for the first time evidences for the toxic nature of oligomeric assemblies of murine amylin and its existence in wild-type, non-transgenic mice.
Subject(s)
Amyloid/immunology , Antibodies/pharmacology , Insulin-Secreting Cells/immunology , Islet Amyloid Polypeptide/immunology , Islet Amyloid Polypeptide/toxicity , Protein Aggregation, Pathological/immunology , Animals , Antibodies/immunology , Humans , Insulin-Secreting Cells/pathology , Male , Mice , Protein Aggregation, Pathological/pathologyABSTRACT
Amylin is a pancreatic hormone cosecreted with insulin that exerts unique roles in metabolism and glucose homeostasis. The therapeutic restoration of postprandial and basal amylin levels is highly desirable in diabetes mellitus. Protein conjugation with the biocompatible polymer polyethylene glycol (PEG) has been shown to extend the biological effects of biopharmaceuticals. We have designed a PEGylated human amylin by using the aminoreactive compound methoxylpolyethylene glycol succinimidyl carbonate (mPEGsc). The synthesis in organic solvent resulted in high yields of monoPEGylated human amylin, which showed large stability against aggregation, an 8 times increase in half-life in vivo compared to the non-conjugated amylin, and pharmacological activity as shown by modulation of cAMP production in MCF-7 cell line, decrease in glucagon and modulation of glycemia following subcutaneous administration in mice. Altogether these data reveal the potential use of PEGylated human amylin for the restoration of fasting amylin levels.