title: A fusion protein derived from plants holds promising potential as a new oral therapy for type 2 diabetes.
abstract: The incretin hormone glucagon-like peptide-1 (GLP-1) is recognized as a promising candidate for the treatment of type 2 diabetes (T2D), with one of its mimetics, exenatide (synthetic exendin-4) having already been licensed for clinical use. We seek to further improve the therapeutic efficacy of exendin-4 (Ex-4) using innovative fusion protein technology. Here, we report the production in plants a fusion protein containing Ex-4 coupled with human transferrin (Ex-4-Tf) and its characterization. We demonstrated that plant-made Ex-4-Tf retained the activity of both proteins. In particular, the fusion protein stimulated insulin release from pancreatic β-cells, promoted β-cell proliferation, stimulated differentiation of pancreatic precursor cells into insulin-producing cells, retained the ability to internalize into human intestinal cells and resisted stomach acid and proteolytic enzymes. Importantly, oral administration of partially purified Ex-4-Tf significantly improved glucose tolerance, whereas commercial Ex-4 administered by the same oral route failed to show any significant improvement in glucose tolerance in mice. Furthermore, intraperitoneal (IP) injection of Ex-4-Tf showed a beneficial effect in mice similar to IP-injected Ex-4. We also showed that plants provide a robust system for the expression of Ex-4-Tf, producing up to 37 μg prEx-4-Tf/g fresh leaf weight in transgenic tobacco and 137 μg prEx-4-Tf/g freshweight in transiently transformed leaves of N. benthamiana. These results indicate that Ex-4-Tf holds substantial promise as a new oral therapy for type 2 diabetes. The production of prEx-4-Tf in plants may offer a convenient and cost-effective method to deliver the antidiabetic medicine in partially processed plant food products.
authors.affiliation: Department of Biology, University of Western Ontario, London, ON, Canada.
authors.forename: Jeehye
authors.initials: J
authors.lastname: Choi
authors.forename: Hong
authors.initials: H
authors.lastname: Diao
authors.forename: Zhi-Chao
authors.initials: ZC
authors.lastname: Feng
authors.forename: Arthur
authors.initials: A
authors.lastname: Lau
authors.forename: Rennian
authors.initials: R
authors.lastname: Wang
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Jevnikar
authors.forename: Shengwu
authors.initials: S
authors.lastname: Ma
mesh_terms: D000284:Administration, Oral; D000818:Animals; D018938:Caco-2 Cells; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004269:DNA, Bacterial / Q000235:genetics; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D004591:Electrophoresis, Polyacrylamide Gel; D004705:Endocytosis / Q000187:drug effects; D020895:Enterocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism; D005822:Genetic Vectors / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology; D005951:Glucose Tolerance Test; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D007274:Injections, Intraperitoneal; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008810:Mice, Inbred C57BL; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D007328:Insulin; D011993:Recombinant Fusion Proteins; C036483:T-DNA; D005947:Glucose
keywords: exendin-4; fusion protein; incretin hormone; novel antidiabetic therapy; plant green bioreactor; transferrin