Glucagon from the phylogenetically ancient paddlefish provides a template for the design of a long-acting peptide with effective anti-diabetic and anti-obesity activities

Dual-agonist incretin peptides from fish with potential for obesity-related Type 2 diabetes therapy - A review

The long-acting glucagon-like peptide-1 receptor (GLP1R) agonist, semaglutide and the unimolecular glucose-dependent insulinotropic polypeptide receptor (GIPR)/GLP1R dual-agonist, tirzepatide have been successfully introduced as therapeutic options for patients with Type-2 diabetes (T2DM) and obesity. Proglucagon-derived peptides from phylogenetically ancient fish act as naturally occurring dual agonists at the GLP1R and the glucagon receptor (GCGR) with lamprey GLP-1 and paddlefish glucagon being the most potent and effective in stimulating insulin release from BRIN-BD11 clonal β-cells. These peptides were also the most effective in lowering blood glucose and elevating plasma insulin concentrations when administered intraperitoneally to overnight-fasted mice together with a glucose load. Zebrafish GIP acts as a dual agonist at the GIPR and GLP1R receptors. Studies with the high fat-fed mouse, an animal model with obesity, impaired glucose-tolerance and insulin-resistance, have shown that twice-daily administration of the long-acting analogs [D-Ala²]palmitoyl-lamprey GLP-1 and [D-Ser²]palmitoyl-paddlefish glucagon over 21 days improves glucose tolerance and insulin sensitivity. This was associated with β-cell proliferation, protection of β-cells against apoptosis, decreased pancreatic glucagon content, improved lipid profile, reduced food intake and selective alteration in the expression of genes involved in β-cell stimulus-secretion coupling. In insulin-deficient Glu^CreERT2;ROSA26-eYFP transgenic mice, the peptides promoted an increase in β-cell mass with positive effects on transdifferentiation of glucagon-producing to insulin-producing cells. Naturally occurring fish dual agonist peptides, particularly lamprey GLP-1 and paddlefish glucagon, provide templates for development into therapeutic agents for obesity-related T2DM.

Lactobacillus rhamnosus LRa05 Ameliorate Hyperglycemia through a Regulating Glucagon-Mediated Signaling Pathway and Gut Microbiota in Type 2 Diabetic Mice

In this study, we aimed to explore the antidiabetic effects of Lactobacillus rhamnosus LRa05 on glucose metabolism and gut microbiota in type 2 diabetes mellitus (T2DM) mice. Our data indicated that the fasting blood glucose levels were reduced by 53.5% after treatment with LRa05 at a dose of 10⁹ CFU·day^-1. Meanwhile, LRa05 attenuated insulin resistance, relieved hepatic oxidative stress, and alleviated metabolic lipopolysaccharide-related inflammation in T2DM mice. LRa05 promoted the expression of glucose transporter 2, while it inhibited the expression of glucagon receptor, glucose-6-phosphatase, cellular adenosine-3'-5'-cyclic monophosphate-dependent protein kinase, and phosphoenolpyruvate carboxykinase in diabetic mice. Meanwhile, LRa05 reshaped gut microbiota, resulting in increased short-chain fatty acid bacteria (Alloprevotella and Bacteroides) and decreased proinflammatory bacteria (Odoribacter and Mucispirillum). Thus, LRa05 may be used as a functional food supplement for modulating the disorder glucose metabolism and gut microbiota in T2DM.

Effects of long-acting analogues of lamprey GLP-1 and paddlefish glucagon on alpha- to beta-cell transdifferentiation in an insulin-deficient transgenic mouse model

The abilities of the long-acting, dual-agonist anti-diabetic peptides [D-Ala² ]palmitoyl-lamprey GLP-1 and [D-Ser² ]palmitoyl-paddlefish glucagon to induce α-cell to β-cell transdifferentiation were investigated in Glu^CreERT2 ;ROSA26-eYFP mice. These animals have been genetically engineered so that yellow fluorescent protein is specifically expressed in glucagon-producing α-cells, thereby allowing cell lineage tracing. Insulin deficiency was produced by treatment of the mice with multiple low doses of streptozotocin. Administration of the peptides (twice daily intraperitoneal injections of 25 nmol/kg body weight over 10 days) to streptozotocin-treated mice produced significant (P < 0.05) increases in pancreatic insulin content and plasma insulin concentrations compared with control mice. Immunohistochemical studies demonstrated a significant (P < 0.05) increase in the % of cells staining for both insulin and fluorescent protein in islets located in the head region of the pancreas (from 10.0 ± 1.3% of total cells in untreated mice to 20.0 ± 3.85% in mice treated with D-Ala² ]palmitoyl-lamprey GLP-1 and to 17.3 ± 1.1% in mice treated with [D-Ser² ]palmitoyl-paddlefish glucagon). Corresponding effects upon islets in the tail region were not significant. The data indicate an improvement in β-cell mass and positive effects on transdifferentiation of glucagon-producing to insulin-producing cells. The study provides further evidence that proglucagon-derived peptides from phylogenetical ancient fish show therapeutic potential for treatment of diabetes.

Antimicrobial Peptides: Classification, Design, Application and Research Progress in Multiple Fields

Antimicrobial peptides (AMPs) are a class of small peptides that widely exist in nature and they are an important part of the innate immune system of different organisms. AMPs have a wide range of inhibitory effects against bacteria, fungi, parasites and viruses. The emergence of antibiotic-resistant microorganisms and the increasing of concerns about the use of antibiotics resulted in the development of AMPs, which have a good application prospect in medicine, food, animal husbandry, agriculture and aquaculture. This review introduces the progress of research on AMPs comprehensively and systematically, including their classification, mechanism of action, design methods, environmental factors affecting their activity, application status, prospects in various fields and problems to be solved. The research progress on antivirus peptides, especially anti-coronavirus (COVID-19) peptides, has been introduced given the COVID-19 pandemic worldwide in 2020.