Abstract
In recent years, glucagon-like peptide-1 (GLP-1) has demonstrated considerable potential in the treatment of type 2 diabetes (T2D) and obesity. However, the half-life of naturally occurring GLP-1 is quite short in vivo. Two common strategies employed for half-life extension are the use of the Albumin-binding domain (ABD) and XTEN polypeptide, which operate through different mechanisms. In this study, we designed an innovative GLP-1 receptor agonist with an extended duration of action. This new construct incorporated an albumin binding domain (ABD) and an XTEN sequence (either XTEN144 or XTEN288) as carriers. We referred to these fusion proteins as GLP-ABD-XTEN144 and GLP-ABD-XTEN288. In an E. coli system, the said constructs were efficaciously produced in substantial quantity. It was observed from in vitro studies that the fusion protein GLP-ABD-XTEN144 demonstrated a five times stronger affinity towards human serum albumin (HSA), boasting a binding affinity (Kd) of 5.50 nM. This was in contrast to GLP-ABD-XTEN288, whose Kd value was registered at 27.78 nM. Moreover, GLP-ABD-XTEN144 presented a half-life of 12.9 h in mice, thus exceeding the corresponding value for GLP-ABD-XTEN288, 7.32 h in mice. Both these fusion proteins significantly mitigated non-fasting blood sugar levels and overall food consumption for 48 h subsequent to a one-time injection in mice. Notably, GLP-ABD-XTEN144 exhibited more pronounced hypoglycemic activity and food inhibitory effects than GLP-ABD-XTEN288. The designed GLP-ABD-XTEN144 fusion protein shows promising prospects for clinical application in T2D treatment. Our findings also suggest that ABD and XTEN polypeptides synergistically contribute to half-life extension, further enhancing the pharmacokinetic characteristics of a payload.