Mechano-sensor Piezo1 inhibits glucagon production in pancreatic α-cells.

OBJECTIVE: Glucagon is a critical hormone regulating glucose metabolism. It stimulates the liver to release glucose under low blood sugar conditions, thereby maintaining blood glucose stability. Excessive glucagon secretion and hyperglycemia is observed in individuals with diabetes. Precise modulation of glucagon is significant to maintain glucose homeostasis. Piezo1 is a mechanosensitive ion channel capable of converting extracellular mechanical forces into intracellular signals, thus regulating hormonal synthesis and secretion. This study aims to investigate the role of Piezo1 in regulating glucagon production in α cells. METHODS: The effects of Piezo1 on glucagon production were examined in normal- or high-fat diet fed α cell-specific Piezo1 knockout mice (Gcg-Piezo1-/-), and the murine pancreatic α cell line αTC1-6. Expression of Proglucagon was investigated by real-time PCR and western blotting. Plasma glucagon and insulin were detected by enzyme immunoassay. RESULTS: Under both normal- and high-fat diet conditions, Gcg-Piezo1-/- mice exhibited increased pancreatic α cell proportion, hyperglucagonemia, impaired glucose tolerance, and activated pancreatic mTORC1 signaling. Activation of Piezo1 by its agonist Yoda1 or overexpression of Piezo1 led to decreased glucagon synthesis and suppressed mTOR signaling pathway in αTC1-6 cells. Additionally, the levels of glucagon in the medium were also reduced. Conversely, knockdown of Piezo1 produced opposite effects. CONCLUSION: Our study uncovers the regulatory role of the Piezo1 ion channel in α cells. Piezo1 influences glucagon production by affecting mTOR signaling pathway.

Gastric mechanosensitive channel Piezo1 regulates ghrelin production and food intake.

Ghrelin, produced mainly by gastric X/A-like cells, triggers a hunger signal to the central nervous system to stimulate appetite. It remains unclear whether X/A-like cells sense gastric distention and thus regulate ghrelin production. Here we show that PIEZO1 expression in X/A-like cells decreases in patients with obesity when compared to controls, whereas it increases after sleeve gastrectomy. Male and female mice with specific loss of Piezo1 in X/A-like cells exhibit hyperghrelinaemia and hyperphagia and are more susceptible to overweight. These phenotypes are associated with impairment of the gastric CaMKKII/CaMKIV-mTOR signalling pathway. Activation of PIEZO1 by Yoda1 or gastric bead implantation inhibits ghrelin production, decreases energy intake and induces weight loss in mice. Inhibition of ghrelin production by Piezo1 through the CaMKKII/CaMKIV-mTOR pathway can be recapitulated in a ghrelin-producing cell line mHypoE-42. Our study reveals a mechanical regulation of ghrelin production and appetite by PIEZO1 of X/A-like cells, which suggests a promising target for anti-obesity therapy.

Construction of antibiotic-induced depression mice model and the function of intestinal microbiota.

Many research studies focus on intestinal microbiota-related depression induced by the usage of antibiotics, but the use of antibiotics is fairly different. To construct an effective antibiotic-induced depression mice model and explore the effect of intestinal microbiota in antibiotic-induced depression, we used several kinds of antibiotic mixtures to induce mice depression and used depression-related behavioral tests and neurobiological factors to evaluate the construction of the antibiotic-induced depression mice model. SPSS statistical software was used to analyze the above data, and the optimal model was selected according to the stability of the results and the simplicity of the modeling methods. Metagenomic analysis and fecal microbiota transplantation (FMT) of intestinal microbiota from antibiotic-induced depression mice were performed to analyze the effect of intestinal microbiota. The results showed that antibiotic mixture A (1.25 µg/mL natamycin, 5 mg/mL neomycin sulfate, and 5 mg/mL bacitracin), antibiotic mixture B (24 mg/mL bacitracin, 24 mg/mL neomycin sulfate, 9.6 mg/mL ampicillin, 4.8 mg/mL meropenem, and 1.47 mg/mL vancomycin), and antibiotic solution D (only containing 5 mg/mL neomycin sulfate) could induce depression-like behavior in mice. By using these antibiotics, the concentrations of norepinephrine (NE), 5-hydroxytryptamine (5-HT), and brain-derived neurotrophic factor (BDNF) in mice hippocampus and prefrontal cortex tissues were significantly decreased. All the above results were consistent with those of chronic unpredictable mild stress (CUMS) depression mice. The FMT results showed that fecal microbiota from antibiotic-induced depressed mice transplanted into normal mice (8 weeks-old male C57BL/6J SPF mice) also could induce depression-like behavior and cause similar changes in neurobiological factors. Metagenomic analysis showed that the community structure of microbiota in the intestinal tract of antibiotic-induced depression mice was significantly different from that in control mice, the intestinal microbiota species diversity in antibiotic-induced depression mice was lower, the lipoic acid metabolism pathway was significantly activated, and the abundance of functional gene lipA was explicitly increased. Quantitative real-time PCR (qPCR) further verified the abundance of enriched bacteria in the intestinal microbiota of antibiotic-induced depression mice. In summary, the specific antibiotic mixtures can induce depression by causing changes in intestinal microbiota in mice. Antibiotic-induced depressed mice show differences in intestinal microbiota abundance, high enrichment of the unique metabolic pathway, and the functional gene.

Antibiotics-induced depression in mice via the microbiota-gut-brain axis.

BACKGROUND: Intestinal dysbacteriosis is associated with depression. This study aimed to establish an antibiotics-induced depression mouse model and explore the mechanism of antibiotic-induced depression. METHODS: C57BL/6 J mice were treated with antibiotics to prepare the antibiotic-induced depression mouse model. Behavioral tests and depression-related bio-markers were examined. To understand the abundance of different bacteria in intestinal flora and screen out the predominant bacterial species, metagenomic analysis of feces was carried out. Finally, we detected the expression of NF-κB-p65 and p-NF-κB-p65 in PFC and the hippocampus using Western blot. RESULTS: Mixtures A and B caused depression-like behavior in mice. Norepinephrine, 5-hydroxytryptamine, and brain-derived neurotrophic factor in hippocampus and PFC of antibiotic-induced depression mice significantly decreased. The serum adrenocorticotropic hormone and corticosterone concentrations increased. The abundance values of Bacteroides thetaiotaomicron, Klebsiella oxytoca, and Klebsiella aerogenes in antibiotic-induced depression mice significantly increased, and the characteristic KO genes and metabolic pathways in antibiotic-induced depression mice were significantly different with in CUMS depression mice (the positive control) and normal mice. The relative levels of p-NF-κB-p65 in antibiotics-induced depression mice were significantly higher than in normal mice. LIMITATIONS: How dysbacteriosis induces inflammation in the central nervous system is unclear. CONCLUSIONS: Specific antibiotic mixture can cause depression-like behavior and changes of depression-related bio-markers in mice. The antibiotic-induced depression mice display changes in the species and metabolism of intestinal bacterial flora. The activation of NF-κB inflammatory signaling pathway in the central nervous system may act as one of the mechanisms in the development of antibiotic-induced depression.

[The role of intestinal microbiota in tumor occurrence, development and immunotherapy: a review].

The intestinal microbiota is a complex micro-ecological system symbiotic with human body, which has attracted increasing attention in recent years. The intestinal microbiota plays important roles not only in maintaining normal physiological functions of the human body but also in the occurrence, development, diagnosis and treatment of tumors. This review summarized the relationship between the intestinal microbiota and tumor, highlighting the mechanisms by which intestinal microbiota modulates tumor occurrence, development and immunotherapy, particularly the immune checkpoint therapy. This review also summarized the currently available methods for enhancing the efficacy of tumor therapy through regulation of intestinal microbiota. Challenges in the field as well as future perspectives were also discussed.