A novel epigenetic mechanism of FXR inhibiting GLP-1 secretion via miR-33 and its downstream targets

Antibiotic-Induced Gut Microbial Dysbiosis Reduces the Growth of Weaning Rats via FXR-Mediated Hepatic IGF-2 Inhibition

The gut microbiota plays a crucial role in postnatal growth, particularly in modulating the development of animals during their growth phase. In this study, we investigated the effects of antibiotic-induced dysbiosis of the gut microbiota on the growth of weaning rats by administering a non-absorbable antibiotic cocktail (ABX) in water for 4 weeks. ABX treatment significantly reduced body weight and feed intake in rats. Concurrently, ABX treatment decreased microbial abundance and diversity in rat ceca, predominantly suppressing microbes associated with bile salt hydrolase (BSH) activity. Furthermore, decreased appetite may be attributed to elevated levels of glucagon-like peptide-1 (GLP-1) in the serum, along with reduced neuropeptide Y (NPY) and increased cocaine and amphetamine-regulated transcript (CART) in the hypothalamus at the mRNA level. Importantly, concentrations of insulin-like growth factor 1 (IGF-1) and insulin-like growth factor 2 (IGF-2) were decreased in the serum and liver of antibiotic-treated rats. These alterations were associated with significant down-regulation of IGF-2 mRNA in the liver and significantly decreased farnesoid X receptor (FXR) protein expression and binding to the IGF-2 promoter. These results indicate that antibiotic-induced gut microbial dysbiosis not only impacts bile acid metabolism but also diminishes rat growth through the FXR-mediated IGF-2 pathway.

Effects of miR-33 Deficiency on Metabolic and Cardiovascular Diseases: Implications for Therapeutic Intervention

MicroRNAs (miRNAs) are small noncoding RNAs that post-transcriptionally inhibit gene expression. These small molecules are involved in several biological conditions such as inflammation, cell growth and proliferation, and regulation of energy metabolism. In the context of metabolic and cardiovascular diseases, miR-33 is of particular interest as it has been implicated in the regulation of lipid and glucose metabolism. This miRNA is located in introns harboured in the genes encoding sterol regulatory element-binding protein (SREBP)-1 and SREBP-2, which are key transcription factors involved in lipid biosynthesis and cholesterol efflux. This review outlines the role of miR-33 in a range of metabolic and cardiovascular pathologies, such as dyslipidaemia, nonalcoholic fatty liver disease (NAFLD), obesity, diabetes, atherosclerosis, and abdominal aortic aneurysm (AAA), and it provides discussion about the effectiveness of miR-33 deficiency as a possible therapeutic strategy to prevent the development of these diseases.

The Effect of Lithocholic Acid on the Gut-Liver Axis

Lithocholic acid (LCA) is a monohydroxy bile acid produced by intestinal flora, which has been found to be associated with a variety of hepatic and intestinal diseases. LCA is previously considered to be toxic, however, recent studies revealed that LCA and its derivatives may exert anti-inflammatory and anti-tumor effects under certain conditions. LCA goes through enterohepatic circulation along with other bile acids, here, we mainly discuss the effects of LCA on the gut-liver axis, including the regulation of gut microbiota, intestinal barrier, and relevant nuclear receptors (VDR, PXR) and G protein-coupled receptor five in related diseases. In addition, we also find that some natural ingredients are involved in regulating the detoxification and excretion of LCA, and the interaction with LCA also mediates its own biological activity.

Molecular study of the proliferation process of beta cells derived from pluripotent stem cells

BACKGROUND

Diabetes mellitus (DM) is a chronic metabolic disorder, increasing in the number of patients and poses a severe threat to human health. Significant advances have been made in DM treatment; the most important of which is differentiation and proliferation of beta cells from IPSCs.

METHODS

Data were collected from PUBMED at various time points up to the academic year of 2020. The related keywords are listed as follows: "Induced pluripotent stem cell", "Proliferation", "Growth factor", "Small molecule", "cardiotoxicity" and "Scaffold."

RESULT

The use of growth factors along with small molecules can be a good strategy for beta-cell proliferation. Also, proliferation of beta cells on nanofibers scaffolds can create a similar in vivo environment, that leads to increased function of beta-cell. Some transcription factors that cause beta cells proliferation play an important role in inflammation; so, it is essential to monitor them to prevent inflammation.

CONCLUSION

Finally, the simultaneous use of growth factors, micronutrients and scaffolds can be an excellent strategy to increase the proliferation and function of beta cells derived from IPSCs.

FTO and PLAG1 Genes Expression and FTO Methylation Predict Changes in Circulating Levels of Adipokines and Gastrointestinal Peptides in Children

Adipokines and gastrointestinal tract hormones are important metabolic parameters, and both epigenetic factors and differential gene expression patterns may be associated with the alterations in their concentrations in children. The function of the FTO gene (FTO alpha-ketoglutarate dependent dioxygenase) in the regulation of the global metabolic rate is well described, whereas the influence of protooncogene PLAG1 (PLAG1 zinc finger) is still not fully understood. A cross-sectional study on a group of 26 children with various BMI values (15.3–41.7; median 28) was carried out. The aim was to evaluate the dependencies between the level of methylation and expression of aforementioned genes with the concentration of selected gastrointestinal tract hormones and adipokines in children. Expression and methylation were measured in peripheral blood mononuclear DNA by a microarray technique and a restriction enzyme method, respectively. All peptide concentrations were determined using the enzyme immunoassay method. The expression level of both FTO and PLAG1 genes was statistically significantly related to the concentration of adipokines: negatively for apelin and leptin receptor, and positively for leptin. Furthermore, both FTO methylation and expression negatively correlated with the concentration of resistin and visfatin. Cholecystokinin was negatively correlated, whereas fibroblast growth factor 21 positively correlated with methylation and expression of the FTO gene, while FTO and PLAG1 expression was negatively associated with the level of cholecystokinin and glucagon-like peptide-1. The PLAG1 gene expression predicts an increase in leptin and decrease in ghrelin levels. Our results indicate that the FTO gene correlates with the concentration of hormones produced by the adipose tissue and gastrointestinal tract, and PLAG1 gene may be involved in adiposity pathogenesis. However, the exact molecular mechanisms still need to be clarified.

Anti-miR33 therapy improved hepatopancreatic lipid and immune metabolism disorders in grass carp, Ctenopharyngodon idella

Lipid metabolism disorders are found ubiquitously in farmed fish and occur as a result of excessive fat accumulation. Previous studies have found that miR-33 is involved in lipid metabolism; however, its role in fish lipid metabolism is unclear. We sought to clarify this relationship in grass carp in vivo and in vitro. Our findings revealed the length of miR-33 to be 65 bp. Phylogenetic tree analysis showed that grass carp miR-33 was most closely related to fish miR-33 (Siganus canaliculatus). Hepatocytes transfected with miR-33 mimic displayed markedly raised TG content (P < 0.05) as well as increased levels of lipid synthesis-related transcription factors (P < 0.05). Compared with blank and saline groups, total serum cholesterol, AST, and LDL levels were suppressed in groups treated with the miR-33 antagomir (P < 0.05). Moreover, the expression levels of PPARγ and SREBP-1c mRNA were significantly decreased in contrast to those found in the control group (P < 0.05). Similar findings were noted in the expression of immune-related proinflammatory molecules (TNFα, IL-1β, IL-6, and NF-κB), which also demonstrated decreased levels (P < 0.05). Conversely, high expressions of anti-inflammatory factors (TGF-β1 and IL-10) were noted (P < 0.05). This investigation strongly supports the role of miR-33 in hepatopancreas-based lipid metabolism and immunity. miR-33 may have been highly conserved in early vertebrates in order to facilitate liver-specific metabolic and immunomodulatory functions. Our findings provide a basis for further investigations exploring the mechanisms surrounding fish lipid metabolism and may aid in preventing and treating immunocompromised fish as well as fish with fatty hepatopancreas, and other metabolic diseases.

The triterpenoid sapogenin (2α-OH-Protopanoxadiol) ameliorates metabolic syndrome via the intestinal FXR/GLP-1 axis through gut microbiota remodelling

Gypenosides, extracts of Gynostemma yixingense, have been traditionally prescribed to improve metabolic syndrome in Asian folk and local traditional medicine hospitals. However, the mechanism of its action remains unclarified. In this work, our results indicated that chronic administration of 2α-OH-protopanoxadiol (GP2), a metabolite of gypenosides in vivo, protected mice from high-fat diet-induced obesity and improved glucose tolerance by improving intestinal L-cell function. Mechanistically, GP2 treatment inhibited the enzymatic activity of bile salt hydrolase and modulated the proportions of the gut microbiota, which led to an increase in the accumulation of tauro-β-muricholic acid (TβMCA) in the intestine. TβMCA induced GLP-1 production and secretion by reducing the transcriptional activity of nuclear receptor farnesoid X receptor (FXR). Transplantation of GP2-remodelled fecal microbiota into antibiotic-treated mice also increased the intestinal TβMCA content and improved intestinal L-cell function. These findings demonstrate that GP2 ameliorates metabolic syndrome at least partly through the intestinal FXR/GLP-1 axis via gut microbiota remodelling and also suggest that GP2 may serve as a promising oral therapeutic agent for metabolic syndrome.