Saponins from Chenopodium quinoa Willd. husks alleviated high-fat-diet-induced hyperlipidemia via modulating the gut microbiota and multiple metabolic pathways.

BACKGROUND: Hyperlipidemia is characterized by abnormally elevated blood lipids. Quinoa saponins (QS) have multiple pharmacological activities, including antitumor, bactericidal and immune-enhancing effects. However, the lipid-lowering effect and mechanisms of QS in vivo have been scarcely reported. METHODS: The effect of QS against hyperlipidemia induced by high-fat diet in rats was explored based on gut microbiota and serum non-targeted metabolomics. RESULTS: The study demonstrated that the supplementation of QS could reduce serum lipids, body weight, liver injury and inflammation. 16S rRNA sequencing demonstrated that QS mildly increased alpha-diversity, altered the overall structure of intestinal flora, decreased the relative richness of Firmicutes, the ratio of Firmicutes/Bacteroidetes (P < 0.05) and increased the relative richness of Actinobacteria, Bacteroidetes, Bifidobacterium, Roseburia and Coprococcus (P < 0.05). Simultaneously, metabolomics analysis showed that QS altered serum functional metabolites with respect to bile acid biosynthesis, arachidonic acid metabolism and taurine and hypotaurine metabolism, which were closely related to bile acid metabolism and fatty acid ß-oxidation. Furthermore, QS increased protein levels of farnesoid X receptor, peroxisome proliferator-activated receptor α and carnitine palmitoyltransferase 1, which were related to the screened metabolic pathways. Spearman correlation analysis showed that there was a correlation between gut microbiota and differential metabolites. CONCLUSION: QS could prevent lipid metabolism disorders in hyperlipidemic rats, which may be closely associated with the regulation of the gut microbiota and multiple metabolic pathways. This study may provide new evidence for QS as natural active substances for the prevention of hyperlipidemia. © 2023 Society of Chemical Industry.

TRIM21 deficiency promotes cell proliferation and tumorigenesis via regulating p21 expression in ovarian cancer.

Tripartite motif-containing 21 (TRIM21) has been reported to have a cancer-promoting or anticancer effect in various tumors; however, its role in ovarian cancer (OC) remains to be elucidated. In this study, we explored the biological function of TRIM21 in OC progression and investigated the potential mechanisms. We found that TRIM21 was remarkably decreased in OC tissues and cell lines compared with adjacent-cancerous tissues and normal ovarian epithelium cell. Decreased expression of TRIM21 in OC patients was significantly correlated with shorter overall and disease-specific survival by The Cancer Genome Atlas database (TCGA) analysis. Functional assays revealed that TRIM21 inhibited the migration and invasion of OC cells; and that TRIM21 also obviously impaired cell proliferation by inhibiting cell cycle progression in vitro and in vivo. Taken together, our results suggest that TRIM21 may be a promising biomarker and target for OC diagnosis and treatment.

Lipid-injured hepatocytes release sOPN to improve macrophage migration via CD44 engagement and pFak-NFκB signaling.

BACKGROUND: The key characteristics in the pathogenesis of nonalcoholic steatohepatitis (NASH) are hepatic lipotoxicity, inflammatory cell infiltration (activated macrophages, in part), and varying degrees of fibrosis. The fatty acid palmitate (PA) can cause hepatocyte cellular dysfunction, but whether and how this process contributes to macrophage-associated inflammation is not well understood. This study aimed to explore whether lipid-injured hepatocytes result in the secretion of osteopontin (sOPN), and how sOPN induces macrophage migration to steatosis hepatocytes. METHODS: Human hepatocellular carcinoma HepG2 cells were incubated with PA to establish the lipotoxicity in hepatocytes model in vitro. The released sOPN was isolated, characterized, and applied to macrophage-like cells differentiated from the human monocytic cell line THP-1 cells. C57BL/6 mice were fed either chow or a diet high in fructose-fat-glucose (FFG) to induce NASH in vivo. Some NASH model mice were also given siSPP1 for two weeks to inhibit the expression of OPN. Related tissues were collected and analyzed by histology, immunofluorescence, ELISA, qRT-PCR, and western blotting. RESULTS: PA upregulated OPN expression and release in human hepatocytes, which drove the migration of macrophages. Incubation of HepG2 cells with palmitate increased mRNA expression and secretion of OPN in cell culture supernatants. Compared with the BSA and siSPP1 groups, treatment with the supernatant derived from PA-treated hepatocytes promoted macrophage migration and activation. The sOPN induction of macrophage migration occurred via CD44 engagement and activation of the pFak-NFκB signaling pathway. Likewise, administration of siSPP1 to NASH mice inhibited the expression and release of OPN, which was associated with decreased liver dysfunction, inflammatory cell infiltration, and even fibrosis. CONCLUSIONS: sOPN, which is released from lipid-injured hepatocytes, emerges as a cytokine driving the migration of macrophages, contributing to an inflammatory response in NASH.

Oleate Ameliorates Palmitate-Induced Impairment of Differentiative Capacity in C2C12 Myoblast Cells.

A common observation in metabolic disorders and aging is the elevation of free fatty acids (FFAs), which can form ectopic fat deposition and result in lipotoxicity. Ectopic fat deposition of skeletal muscle has been recognized as an important component of aging, frailty, and sarcopenia. Previous studies have suggested that lipotoxicity caused by FFAs mainly stemmed from saturated fatty acids and decreased unsaturated/saturated fatty acid ratio in serum are also observed among metabolic disorder patients. However, the different effects of saturated fatty acids and unsaturated fatty acids on skeletal muscle are not fully elucidated. In this study, we verified that palmitate (PA), a saturated fatty acid, could lead to impaired differentiative capacity of C2C12 myoblasts by affecting Pax7, MyoD, and myogenin (MyoG), which are master regulators of lineage specification and the myogenic program. Then, oleate (OA), a monounsaturated fatty acid, were added to culture medium together with PA. Results showed that OA could ameliorate the impairment of differentiative capacity in C2C12 myoblast cells. In addition, we found PI3K/Akt signaling pathway played an important role during the process by RNA sequencing and bioinformatics analysis. The positive effect of OA on myoblast differentiative capacity disappeared if PI3K inhibitor LY294002 was added. In conclusion, our study showed that PA could destroy differentiative capacity of C2C12 myoblasts by affecting the expression of Pax7, MyoD, and MyoG, and OA could improve this impairment through PI3K/Akt signaling pathway.

Secretory galectin-3 induced by glucocorticoid stress triggers stemness exhaustion of hepatic progenitor cells.

Adult progenitor cell populations typically exist in a quiescent state within a controlled niche environment. However, various stresses or forms of damage can disrupt this state, which often leads to dysfunction and aging. We built a glucocorticoid (GC)-induced liver damage model of mice, found that GC stress induced liver damage, leading to consequences for progenitor cells expansion. However, the mechanisms by which niche factors cause progenitor cells proliferation are largely unknown. We demonstrate that, within the liver progenitor cells niche, Galectin-3 (Gal-3) is responsible for driving a subset of progenitor cells to break quiescence. We show that GC stress causes aging of the niche, which induces the up-regulation of Gal-3. The increased Gal-3 population increasingly interacts with the progenitor cell marker CD133, which triggers focal adhesion kinase (FAK)/AMP-activated kinase (AMPK) signaling. This results in the loss of quiescence and leads to the eventual stemness exhaustion of progenitor cells. Conversely, blocking Gal-3 with the inhibitor TD139 prevents the loss of stemness and improves liver function. These experiments identify a stress-dependent change in progenitor cell niche that directly influence liver progenitor cell quiescence and function.

PPP1R3C mediates metformin-inhibited hepatic gluconeogenesis.

BACKGROUND: Metformin has been widely used to alleviate hyperglycemia in patients with type 2 diabetes mainly via suppressing hepatic gluconeogenesis. However, the underlying mechanism remains incompletely clear. Here, we aimed to explore the role of PPP1R3C in metformin-mediated inhibition of hepatic gluconeogenesis. METHODS: The differentially expressed genes in primary mouse hepatocytes incubated with 8-Br-cAMP and metformin were analyzed by microarrays. Hepatic glucose production and gluconeogenic gene expressions were detected after adenovirus-mediated overexpression or silence of PPP1R3C in vitro and in vivo. The phosphorylation level and location of transducer of regulated CREB activity 2 (TORC2) were determined by Western blot and immunofluorescence. RESULTS: Metformin and adenovirus-mediated activation of AMPK suppressed 8-Br-cAMP-stimulated Ppp1r3c mRNA expression in primary mouse hepatocytes. Overexpression of PPP1R3C in primary mouse hepatocytes or the livers of wild-type mice promoted hepatic glucose production and gluconeogenic gene expressions. On the contrary, adenovirus-mediated knockdown of PPP1R3C in primary mouse hepatocytes decreased hepatic gluconeogenesis, with the suppression of cAMP-stimulated gluconeogenic gene expressions and TORC2 dephosphorylation. Notably, Ppp1r3c expression was increased in the liver of db/db mice. After PPP1R3C silence in the livers of wild-type and db/db mice, blood glucose levels and hepatic glucose production were markedly lowered, with decreased expressions of key gluconeogenic enzymes and transcript factors as well as liver glycogen content. CONCLUSION: Metformin-activated AMPK decreases hepatic PPP1R3C expression, leading to the suppression of hepatic gluconeogenesis through blocking cAMP-stimulated TORC2 dephosphorylation. Hepatic specific silence of PPP1R3C provides a promising therapeutic strategy for type 2 diabetes.

Butyrate stimulates hepatic gluconeogenesis in mouse primary hepatocytes.

Butyrate is a major short-chain fatty acid (SCFA) produced by microbial fermentation of dietary fiber in the gastrointestinal tract. Butyrate is also a well-known broad-spectrum histone deacetylase (HDAC) inhibitor. Butyrate has been reported to improve energy metabolism in rodents, which is associated with its beneficial effects on skeletal muscle, brown fat tissue and pancreatic ß-cells. The present study investigated the direct effect of butyrate on hepatic gluconeogenesis in mouse primary hepatocytes and the underlying mechanism. Isolated mouse primary hepatocytes were incubated with sodium butyrate, other HDAC inhibitors and other SCFAs. Hepatic glucose production was measured and gluconeogenic gene expression was detected by polymerase chain reaction analysis. The phosphorylation of cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) was assessed by western blot analysis. The results revealed that sodium butyrate dose-dependently increased hepatic glucose production and gluconeogenic gene expression in isolated mouse primary hepatocytes. Trichostatin A, a potent broad-spectrum HDAC inhibitor, had the opposite effect. Similar to sodium butyrate, propionate, which is another SCFA, promoted hepatic glucose production and gluconeogenic gene expression in the presence or absence of gluconeogenic substrates, which were further enhanced by cAMP. Furthermore, sodium butyrate also increased the accumulation of intracellular ATP and induced the phosphorylation of CREB in mouse hepatocytes. In conclusion, the present study suggested that butyrate stimulates hepatic gluconeogenesis and induces gluconeogenic gene expression as a substrate and cAMP/CREB signaling activator.

Expression profile analysis of long non-coding RNAs involved in the metformin-inhibited gluconeogenesis of primary mouse hepatocytes.

Long non-coding RNAs (lncRNAs) have been demonstrated to regulate metabolic tissue development and function, including adipogenesis, hepatic lipid metabolism, islet function and energy balance. However, the role of lncRNAs in gluconeogenesis remains completely unknown. Metformin reduces glucose output mainly via the inhibition of gluconeogenesis. In the present study, the lncRNA expression profile of primary mouse hepatocytes exposed to cyclic adenosine monophosphate (cAMP), a gluconeogenic stimulus, with or without metformin was analyzed by microarray. Among the 22,016 lncRNAs that were identified, 456 were upregulated and 409 were downregulated by cAMP (fold-change ≥2.0). Furthermore, the cAMP-induced upregulation of 189 lncRNAs and downregulation of 167 lncRNAs was attenuated by metformin. The expression levels of eight lncRNAs were validated by reverse transcription-quantitative polymerase chain reaction, and the results were consistent with those of the microarray analysis. Among them, two lncRNAs NR_027710 and ENSMUST00000138573, were identified to have an association with two protein coding genes, namely peroxisome proliferator-activated receptor-γ coactivator-1α, a critical transcriptional coactivator in gluconeogenesis, and G protein-coupled receptor 155, respectively. The two protein coding genes exhibited similar expression patterns to their associated lncRNAs. The findings of the present study suggest that lncRNAs are potentially involved in the regulation of gluconeogenesis.

Glucose potentiates ß-cell function by inducing Tph1 expression in rat islets.

Impaired pancreatic ß-cell function is the primary defect in type 2 diabetes. Glucose is an important regulator of ß-cell growth and function; however, the mechanisms that are involved in the chronic adaptation of ß cells to hyperglycemia remain largely unknown. In the present study, global gene expression patterns revealed that tryptophan hydroxylase 1 (Tph1) was the most profound of genes that are up-regulated in rat islets exposed to high glucose. Calcium and cAMP signals synergistically mediated glucose-stimulated Tph1 transcription in ß cells by activating cAMP-responsive element-binding protein and promoting its binding with a Tph1 promoter. Similar to in vitro results, in vivo infusion of high glucose also strongly induced Tph1 expression and serotonin production in rat islets, along with enhanced islet function. Inhibition or knockdown of Tph1 markedly decreased glucose-potentiated insulin secretion. In contrast, overexpression of Tph1 augmented glucose-stimulated insulin secretion in rat islets by up-regulating the expression of genes that are related to islet function. In addition, the long-acting glucagon-like peptide 1 receptor agonist, exendin-4, stimulated Tph1 expression in a glucose-dependent manner. Knockdown of Tph1 inhibited exendin-4-potentiated insulin secretion in rat islets. These findings suggest that Tph1 mediates the compensation of islet function induced by glucose, and that promoting Tph1 expression in pancreatic ß cells will provide a new strategy for the treatment of type 2 diabetes mellitus.-Zhang, Y., Deng, R., Yang, X., Xu, W., Liu, Y., Li, F., Zhang, J., Tang, H., Ji, X., Bi, Y., Wang, X., Zhou, L., Ning, G. Glucose potentiates ß-cell function by inducing Tph1 expression in rat islets.

Glucose enhances rat islet function via stimulating CART expression.

Cocaine- and amphetamine-regulated transcript (CART) is an anorexigenic peptide widely expressed in the central and peripheral nervous systems, as well as in endocrine cells. CART is markedly upregulated in the ß-cells of several rodent models of type-2 diabetes. The stimulatory effect of exogenous CART peptide on insulin secretion is cAMP dependent. Glucose is the most important regulator of islet function. However, the role of CART in glucose-potentiated insulin secretion remains unclear. Here, our results showed that glucose time- and dose-dependently elicited CART mRNA expression in rat islets. Both the glucokinase agonist GKA50 and the long-acting GLP-1 analogue exendin-4 increased CART mRNA expression. The protein kinase A (PKA) inhibitor H89 and the inactivation of cAMP response element-binding protein (CREB) suppressed forskolin-stimulated CART mRNA expression. Furthermore, CART overexpression amplified insulin secretion from rat islets in response to glucose and forskolin, and ameliorated dexamethasone-impaired insulin secretion. These findings suggest that islet-derived CART is involved, at least in part, in high glucose-potentiated pancreatic ß-cell function.

The effect of posterior scleral reinforcement for high myopia macular splitting.

This study investigated the effect of posterior scleral reinforcement for high myopia macular splitting in 15 patients with high myopia and macular splitting (20 eyes), including three eyes with shallow retinal detachment. Main outcome measures included best-corrected visual acuity, refractive error, axial length, optical coherence tomography (OCT) findings and post-surgical complications. Best-corrected visual acuity, myopial dioptres and axial length reduced significantly post-surgery. The OCT findings showed different degrees of reduction in the split-cavity between inner and outer retinal layers, and that retinal thickness declined significantly post-operatively. No serious complications were observed. Posterior scleral reinforcement was effective, with a good safety profile, for patients with high myopia macular splitting with or without retinal detachment.

Posterior scleral reinforcement in the treatment of macular retinoschisis in highly myopic patients.

The objective of this study was to evaluate the clinical curative effect of posterior scleral reinforcement for macular retinoschisis in highly myopic patients. Twenty-four highly myopic eyes with macular retinoschisis were treated with posterior scleral reinforcement surgery from September 2005 to March 2007 in our hospital. Visual field, best corrected vision acuity (BCVA), refractive error, optical coherence tomography and A/B Scan ultrasound graphy results were retrospectively analysed. The central visual field in 18 eyes was improved after surgery; optical coherence tomography showed complete resolution of the myopic foveoschisis in 20 (83.33%) of the 24 eyes after surgery. The postoperative BCVA was improved by 0.1 or more in 18 eyes (75%), and remained within 0.1 of the preoperative BCVA in five eyes (20.83%) at the end of follow-up. Compared with the preoperative data of 23 eyes, the final magnitude of myopia after surgery was significantly decreased (t = 3.527, P = 0.002). In conclusion, this procedure can effectively treat highly myopic patients with macular retinoschisis without macular hole or retinal detachment, and might be better for maintaining central vision and preventing the occurrence of complications.