Engineering of a Biologically Active Glycosylated Glucagon-Like Peptide-1 Analogue

Glucagon-like peptide receptor (GLP-1R) agonists (e.g., semaglutide, liraglutide, etc.) are efficient treatment options for people with type 2 diabetes and obesity. The manufacturing method to produce semaglutide, a blockbuster GLP-1 drug on the market, involves multistep synthesis. The large peptide has a hydrophobic fatty acid side chain that makes it sparingly soluble, and its handling, purification, and large-scale production difficult. The growing demand for semaglutide that the manufacturer is not capable of addressing immediately triggered a worldwide shortage. Thus, we have developed a potential alternative analogue to semaglutide by replacing the hydrophobic fatty acid with a hydrophilic human complex-type biantennary oligosaccharide. Our novel glycoGLP-1 analogue was isolated in an ∼10-fold higher yield compared with semaglutide. Importantly, our glycoGLP-1 analogue possessed a similar GLP-1R activation potency to semaglutide and was biologically active in vivo in reducing glucose levels to a similar degree as semaglutide.

Allosteric Modulators Enhancing GLP-1 Binding to GLP-1R via a Transmembrane Site

The glucagon-like peptide-1 receptor (GLP-1R) is a well-established drug target for the treatment of type II diabetes. The development of small-molecule positive allosteric modulators (PAMs) of GLP-1R is a promising therapeutic strategy. Here, we report the discovery and characterization of PAMs with distinct chemotypes, binding to a cryptic pocket formed by the cytoplasmic half of TM3, TM5, and TM6. Molecular dynamic simulations and mutagenesis studies indicate that the PAM enlarges the orthosteric pocket to facilitate GLP-1 binding. Further signaling assays characterized their probe-dependent signaling profiles. Our findings provide mechanistic insights into fine-tuning GLP-1R via this allosteric pocket and open up new avenues to design small-molecule drugs for class B G-protein-coupled receptors.

Insights into agonist-elicited activation of the human glucose-dependent insulinotropic polypeptide receptor

Glucose-dependent insulinotropic polypeptide (GIP) and its receptor (GIPR) are part of the incretin system that regulates glucose homeostasis. A series of GIPR residues putatively important for ligand binding and receptor activation were mutated and pharmacologically evaluated using GIPR selective agonists in cAMP accumulation, ERK1/2 phosphorylation (pERK1/2) and β-arrestin 2 recruitment assays. The impact of mutation on ligand efficacy was determined by operational modelling of experimental data for each mutant, with results mapped onto the full-length, active-state GIPR structure. Two interaction networks, comprising transmembrane helix (TM) 7, TM1 and TM2, and extracellular loop (ECL) 2, TM5 and ECL3 were revealed, respectively. Both networks were critical for Gα_s-mediated cAMP accumulation and the recruitment of β-arrestin 2, however, cAMP response was more sensitive to alanine substitution, with most mutated residues displaying reduced signaling. Unlike the other two assays, activation of ERK1/2 was largely independent of the network involving ECL2, TM5 and ECL3, indicating that pERK1/2 is at least partially distinct from Gα_s or β-arrestin pathways and this network is also crucial for potential biased agonism at GIPR. Collectively, our work advances understanding of the structure-function relationship of GIPR and provides a framework for the design and/or interpretation of GIP analogues with unique signaling profiles.

Construction and Functional Analysis of the Recombinant Bacteriocins Weissellicin-MBF from Weissella confusa MBF8-1

BACKGROUND

Bacteriocins (Bac1, Bac2, and Bac3) from Weissella confusa MBF8-1, weissellicin- MBF, have been reported as potential alternative substances as well as complements to the existing antibiotics against many antimicrobial-resistant pathogens. Previously, the genes encoded in the large plasmid, pWcMBF8-1, and the spermicidal activity of their synthetic peptides, originally discovered Indonesia, have been studied. Three synthetic bacteriocins peptides of this weissellicin-MBF have been reported for their potential activities, i.e. antibacterial and spermicidal.

OBJECTIVE

The aim of this study was to construct the recombinant Bacteriocin (r-Bac) genes, as well as to investigate the gene expressions and their functional analysis.

METHODS

Here, the recombinant Bacteriocin (r-Bac) genes were constructed and the recombinant peptides (r-Bac1, r-Bac2, and r-Bac3) in B. subtilis DB403 cells were produced on a large scale. After purification, using the His-tag affinity column, their potential bioactivities were measured as well as their antibacterial minimum inhibitory concentrations against Leuconostoc mesenteroides and Micrococcus luteus, were determined.

RESULTS

Pure His-tag-recombinant Bac1, Bac2, and Bac3 were obtained and they could inhibit the growth of L. mesenteroides and M. luteus.

CONCLUSION

The recombinant bacteriocin could be obtained although with weak activity in inhibiting gram-positive bacterial growth.

G protein-coupled receptors: structure- and function-based drug discovery

As one of the most successful therapeutic target families, G protein-coupled receptors (GPCRs) have experienced a transformation from random ligand screening to knowledge-driven drug design. We are eye-witnessing tremendous progresses made recently in the understanding of their structure-function relationships that facilitated drug development at an unprecedented pace. This article intends to provide a comprehensive overview of this important field to a broader readership that shares some common interests in drug discovery.

High-throughput screening for small molecule inhibitors of the type-I interferon signaling pathway

Interferons (IFNs) are cytokines with fundamental roles in resistance to infections, cancer and other diseases. Type-I IFNs, interferon α (IFN-α) and interferon β (IFN-β), act through a shared receptor complex (IFNAR) comprised of IFNAR1 and IFNAR2 subunits. Binding of type-I IFN to IFNAR1 will robustly activate Janus activated kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway. Aberrant activation of the type-I IFN response results in a spectrum of disorders called interferonopathies. The purpose of this research is to develop an assay for high-throughput screening (HTS) of small molecule inhibitors of the type-I IFN signaling pathway. Inhibition of type-I IFN signaling can be beneficial in terms of therapeutic use and understanding the underlying mechanism of action. We report here a HTS campaign with the secreted embryonic alkaline phosphatase (SEAP) reporter gene assay against 32,000 compounds which yielded 25 confirmed hits. These compounds were subsequently characterized for their cytotoxicity, effects on STAT phosphorylation and activities in IFN regulatory factor (IRF) transcription.