A fusion protein derived from plants holds promising potential as a new oral therapy for type 2 diabetes

Abstract

email sma@uwo.ca) † These authors contributed equally to this work.Keywords: plant green bioreactor, incretin hormone, exendin-4, transferrin, fusion protein, novel antidiabetic therapy. SummaryThe 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 b-cells, promoted b-cell proliferation, stimulated differentiation of pancreatic precursor cells into insulinproducing 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 lg prEx-4-Tf/g fresh leaf weight in transgenic tobacco and 137 lg 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.

Dl‐3‐n‐butylphthalide attenuates acute inflammatory activation in rats with spinal cord injury by inhibiting microglial TLR4/NF‐κB signalling

“…Signal intensities were quantified by densitometry using Image Lab 3.0 software (Bio‐Rad). Data were normalized to total or loading controls .…”

Nerve growth factor-induced Akt/mTOR activation protects the ischemic heart via restoring autophagic flux and attenuating ubiquitinated protein accumulation

“…The signals were visualized with the ChemiDic XRS+ Imaging System (Bio-Rad Laboratories, Hercules, CA, USA). The band densities were quantified with Image J (National Institutes of Health) [44, 45]. …”

Expression and functional evaluation of biopharmaceuticals made in plant chloroplasts

“…Due to the extremely short half-life of GLP-1 in serum (<2 min), type II diabetes treatment has focused on dipeptidyl peptidase IV (DPP-IV) resistant analogs like exendin-4 (EX4), which has significantly longer serum half-life (~4 h). Oral delivery of plant derived EX4 fused with human transporter protein (transferrin) to mice exerted a glucose-lowering effect by stimulating insulin secretion, as well as promoting differentiation and proliferation of pancreatic β-cells [29]. Moreover, oral administration of plant made EX4-CTB fusion protein significantly improved glucose regulation in mice.…”