protein, GLP-1/ hIgG2, consisting of GLP-1 fused with human IgG Fc, retaines native GLP-1 properties and demonstrates long-acting characteristics. This recombinant GLP-1 fusion protein has anti-diabetic and other beneficial features of GLP-1. The IgG fusion molecules potentially are large molecular weight homodimers and are not expected to be rapidly cleared by the kidneys, and thus have a substantially longer half-life and better metabolic profiles. Fc fusion based drugs provide a numbers of advantages and have become credible alternatives to monoclonal antibodies as therapeutics. GLP-1/hIgG2 fusion molecules are produced as homodimers, comprising of two IgG CH2/CH3 chains fused to a pair of GLP-1 molecules with molecular mass of 70 kilo Daltons and had a substantially longer half-life. Our pharmacokinetic data showed that that the fusion proteins are detectable a week after a single dose injection in mice. IPGTT showed that the glucoregulatory effects of GLP-1/hIgG2 were maintained 8 days after a single dose-injection, suggesting that the detected fusion protein were still biologically active. Although the fusion protein contains a native GLP-1, the GLP-1 in the fusion design is expected to have reduced susceptibility 17888033 to degradation since such degrading enzymes have a preference for smaller peptides. Indeed, our in vitro stability assay results supported this notion, which is also supported by our previous evidence that in vivo expression of GLP-1/mIgG-Fc or exendin-4/mIgG-Fc fusion proteins achieved equivalent Degarelix biological activity efficacy in mice. Ligand-receptor binding parameters suggest that GLP-1/hIgG2 has high binding affinity to the GLP-1R in INS-1 cells which is comparable to those of exending-4 as well as those of native GLP-1. The retained high binding affinity is also suggestive of the fact that the fusion process most likely did not alter the proximal conformation of native GLP-1. It is likely that GLP-1/hIgG2 that contains the genetically engineered linker, equivalent to the natural hinge region of human 
IgG2, may provide flexibility and sufficient spatial structure for appropriate binding of GLP-1 to 22948146 its receptor. It is of note that the design of the linker sequence of the genetic fusion is considered to be critical for maintenance of peptide activity. A recent study by Picha KM et al. reported that CNTO736, a GLP-1 peptide analog, genetically fused to a Fc portion of IgG has an optimized linker sequence which provided higher activity when compared to other reported fusions of GLP-1 to an IgG1 Fc or albumin. Our results indicate that, a hinge region of human IgG2 that functions as a linker, provide an optimized binding of fused GLP-1 molecule to its receptor. Furthermore, the dimeric GLP-1, conjugated with an Fc fragment, is expected to increase the ligand avidity since homodimeric GLP-1 can potentially recruit additional GLP-1Rs and amplify intracellular signaling via preformed GPCR dimers/oligomers. The ability of the fusion protein to stimulate insulin secretion in INS-1 cells in a glucose-dependent manner further suggests that the GLP-1 fusion protein retains the biological activities of the native GLP-1. Using human IgG2 in the fusion protein appears to be advantageous over the use of other subclasses of IgG. Of all human IgG isotypes, IgG2 has the lowest affinity for FccRI. FccRI is a high affinity Fc receptor that binds IgG1, IgG3, or IgG4 in monomeric form, and can induce antibody dependent cellular toxicity . IgG2-coated red blood
