Gene therapy of diabetes using a novel GLP-1/IgG1-Fc fusion construct normalizes glucose levels in db/db mice.
Glucagon-like peptide (GLP-1), a major physiological incretin, plays numerous important roles in modulating blood glucose homeostasis and has been proposed for the treatment of type 2 diabetes. The major obstacles for using native GLP-1 as a therapeutic agent are that it must be delivered by a parenteral route and has a short half-life. In an attempt to develop a strategy to prolong the physiological t(1/2) and enhance the potency of GLP-1, a fusion protein consisting of active human GLP-1 and mouse IgG(1) heavy chain constant regions (GLP-1/Fc) was generated. A plasmid encoding an IgK leader peptide-driven secretable fusion protein of the active GLP-1 and IgG(1)-Fc was constructed for mammalian expression. This plasmid allows for expression of bivalent GLP-1 peptide ligands as a result of IgG-Fc homodimerization. In vitro studies employing purified GLP-1/Fc indicate that the fusion protein is functional and elevates cAMP levels in insulin-secreting INS-1 cells. In addition, it stimulates insulin secretion in a glucose concentration-dependent manner. Intramuscular gene transfer of the plasmid in db/db mice demonstrated that expression of the GLP-1/Fc peptide normalizes glucose tolerance by enhancing insulin secretion and suppressing glucagon release. This strategy of using a bivalent GLP-1/Fc fusion protein as a therapeutic agent is a novel approach for the treatment of diabetes.
Kumar
M
M
Department of Medicine, University of Toronto, Ontario, Canada.
Hunag
Y
Y
Glinka
Y
Y
Prud'homme
G J
GJ
Wang
Q
Q
D000818:Animals; D019149:Bioreactors; D001786:Blood Glucose / Q000032:analysis; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000628:therapy*; D015316:Genetic Therapy / Q000379:methods*; D005934:Glucagon / Q000097:blood; D052216:Glucagon-Like Peptide 1 / Q000235:genetics*; D006207:Half-Life; D007141:Immunoglobulin Fc Fragments / Q000235:genetics*; D007074:Immunoglobulin G / Q000235:genetics*; D007328:Insulin / Q000097:blood; D051379:Mice; D008820:Mice, Obese; D023421:Models, Animal; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000627:therapeutic use*; D014162:Transfection / Q000379:methods
D001786:Blood Glucose; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007328:Insulin; D011993:Recombinant Fusion Proteins; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D000242:Cyclic AMP