miR-363-3p/PTEN is involved in the regulation of lipid metabolism by genistein in HepG2 cells via ERß.

BACKGROUND: Genistein (GEN) is one of the most well-known phytoestrogens identified in various legumes. Although increasing evidence shows GEN has a potential use in phytotherapy to regulate lipid metabolism, its therapeutic mechanisms have not yet been completely elucidated, especially epigenetic alterations of miRNAs to alleviate lipid accumulation in the liver remains unknown. PURPOSE: To clarify how GEN modulates the miRNA profile in HepG2 cells and investigate molecular mechanisms of the modulated miRNA on regulating hepatic lipid metabolism. METHODS: The miRNA microarray was performed to compare the miRNAs expression patterns, followed by determining principal miRNA and its target gene associated with hepatic lipid metabolism modulated by GEN. miR-363-3p mimics (mi) and phosphatase and tensin homolog (PTEN)-siRNA were transfected into HepG2 cells and GEN was further treated with the cells for 24 h RESULTS: GEN induced downregulation of miR-363-3p and upregulation of PTEN, which was a target mRNA of miR-363-3p. The miR-363-3p mi led to an upregulation of sterol-regulatory element-binding protein-1c (SREBP-1c) and its downstream lipid synthesis-related factors in HepG2 cells. In addition, the inhibition of PTEN led to an increase of lipogenesis, which was associated with the AKT/mTOR signal regulation. However, GEN treatment could abrogate the lipogenic effects of miR-363-3p mi or PTEN siRNA. The modulation was associated with estrogen receptor ß (ERß). CONCLUSION: We discerned a new mechanism that GEN regulated hepatic lipid metabolism by inhibiting miR-363-3p, which could be mediated via ERß and by targeting PTEN in HepG2 cells. Additionally, GEN reduced hepatic lipid accumulation by regulating PTEN-AKT/mTOR signal. It implicated a protective role of GEN by elucidating its epigenetic modification of the miRNA modulated by ERß on improving hepatic lipid metabolism and provided novel evidence of the mechanism on targeting miR-363-3p/PTEN in treating hepatic lipid disorders.

Mechanism of Astragalus membranaceus Alleviating Acquired Hyperlipidemia Induced by High-Fat Diet through Regulating Lipid Metabolism.

Astragalus membranaceus (AM) is a food and medicinal homologous plant. The current research is aimed to investigate the beneficial effects and mechanisms of AM in treating acquired hyperlipidemia. The network pharmacology and bioinformatics analysis results showed 481 AM-related targets and 474 acquired hyperlipidemia-associated targets, and 101 candidate targets were obtained through the intersection, mainly enriched in endocrine resistance, AGE-RAGE in diabetic complications and p53 signaling pathways. Quercetin, kaempferol, calycosin, formononetin and isorhamnetin were determined as the candidate active components of AM in the treatment of acquired hyperlipidemia. Moreover, key targets of AM, namely, AKT serine/threonine kinase 1 (AKT1), vascular endothelial growth factor A (VEGFA), cyclin D1 (CCND1) and estrogen receptor 1 (ESR1), were screened out, which were closely related to adipogenesis, fatty acid metabolism and bile acid metabolism. The subsequent animal experiments showed that AM extract treatment improved the lipid profiles of the high-fat diet (HFD)-fed mice by reducing lipogenesis and increasing lipolysis and lipid ß-oxidation, which were associated with the downregulating of AKT1 and CCND1, and the upregulating of VEGFA and ESR1 in liver and adipose tissue. Overall, AM alleviated acquired hyperlipidemia through regulating lipid metabolism, and AKT1, VEGFA, CCND1 and ESR1 might be the key targets.

Anabolic Activity of a Soy Extract and Three Major Isoflavones in C2C12 Myotubes.

Isoflavones have been reported to stimulate muscle growth. The aim of this in vitro study was to examine anabolic activity and associated molecular mechanisms of a soy extract (SoyEx), isoflavone aglycones, and a mixture simulating the composition of SoyEx in C2C12 myotubes. C2C12 cells were differentiated into myotubes. The effects of SoyEx, genistein, daidzein, glycitein, and the mixture of genistein-daidzein-glycitein (Mix) on myotube diameter and number were determined. In addition, the expression of genes and proteins associated with anabolic activity was analyzed. Treatment with SoyEx, genistein, and Mix led to a significant increase of myotube diameter and an increase of the number of myotubes per area compared to the control cell. The increase of diameter by SoyEx was antagonized by an antiestrogen, not by an antiandrogen. Furthermore, gene expressions of insulin growth factor (IGF)-1 and its receptor (IGF-1R), as well as protein expression of myosin heavy chain (MHC), were significantly increased by SoyEx, genistein, and Mix. The effects induced by genistein and Mix were comparable to SoyEx. In conclusion, SoyEx displays an anabolic activity in C2C12 myotubes by binding to ER and modulating IGF-1 and MHC expression. Our studies with isoflavone aglycones and Mix indicate that the isoflavone aglycone with the highest anabolic bioactivity in SoyEx is genistein.

Combinatory effects of phytoestrogens and exercise on body fat mass and lipid metabolism in ovariectomized female rats.

The purpose of this study was to investigate the combinatory effects of an isoflavone (ISO)-rich diet and exercise on fat mass and lipid metabolism in ovariectomized (OVX) rats. Therefore the female Wistar rats were sedentary, performed an intense treadmill uphill running, received ISOs, or a combination of ISOs and running after ovariectomy. The exercise reduced visceral fat mass, adipocyte size and serum leptin in Sham animals and antagonized the increases of these parameters induced by OVX. ISOs reduced OVX induced increase of serum leptin. The combination of training and ISOs was most effective in reducing serum triglyceride levels. In OVX rats the training stimulated the expression of genes associated with fatty acid synthesis (SREBP-1c and FAS) in adipose tissue, soleus muscle, liver and genes associated with fatty acid oxidation (PPARδ and PGC-1α) in adipose tissue. ISOs stimulated the expression of SREBP-1c and FAS in soleus muscle and PGC-1α in adipose tissue, whereas suppressed hepatic SREBP-1c and FAS expression. Strong additive effects of ISOs combined with the training were observed for PPARδ and PGC-1α expressions in soleus muscle. In conclusion our results demonstrate that both the training and ISOs affect fat mass and fatty acid metabolism in OVX rats. The training seems to have a higher impact than ISO exposure in regulating gene expression in adipose tissue. However, the strongest effects for several of the addressed parameters could be observed in the combination group especially in the soleus muscle. Therefore a combination of training and an ISO-rich diet may have beneficial effects on fatty acid metabolism and could be a concept for the prevention of obesity in postmenopausal females.

Estrogen receptor beta is involved in skeletal muscle hypertrophy induced by the phytoecdysteroid ecdysterone.

SCOPE: The phytoectysteroid ecdysterone (Ecdy) was reported to stimulate protein synthesis and enhance physical performance. The aim of this study was to investigate underlying molecular mechanisms particularly the role of ER beta (ERß). RESULTS: In male rats, Ecdy treatment increased muscle fiber size, serum IGF-1 increased, and corticosteron and 17ß-estradiol (E2) decreased. In differentiated C2C12 myoblastoma cells, treatment with Ecdy, dihydrotestosterone, IGF-1 but also E2 results in hypertrophy. Hypertrophy induced by E2 and Ecdy could be antagonized with an antiestrogen but not by an antiandrogen. In HEK293 cells transfected with ER alpha (ERα) or ERß, Ecdy treatment transactivated a reporter gene. To elucidate the role of ERß in Ecdy-mediated muscle hypertrophy, C2C12 myotubes were treated with ERα (ALPHA) and ERß (BETA) selective ligands. Ecdy and BETA treatment but not ALPHA induced hypertrophy. The effect of Ecdy, E2, and BETA could be antagonized by an ERß-selective antagonist (ANTIBETA). In summary, our results indicate that ERß is involved in the mediation of the anabolic activity of the Ecdy. CONCLUSION: These findings provide new therapeutic perspectives for the treatment of muscle injuries, sarcopenia, and cachectic disease, but also imply that such a substance could be abused for doping purposes.

Macrophage immunomodulatory activity of a purified polysaccharide isolated from Ganoderma atrum.

The objective of this study was to evaluate the immunomodulatory effects of the purified Ganoderma atrum polysaccharide (PSG-1) on murine macrophage cell line RAW264.7. Phagocytotic assay by fluorescein isothiocyanate-dextran internalization showed that PSG-1 stimulated the phagocytosis of macrophages. G. atrum polysaccharide increased the production of NO, and the level of mRNA expression of inducible nitric oxide synthase in a dose-response manner. G. atrum polysaccharide also dose-dependently induced the release of TNF-α and interleukin-1ß. Generation of reactive oxygen species was promoted by PSG-1, as determined by flow cytometry. Moreover, PSG-1 induced nuclear factor-κB activation by elevation of p65 nuclear translocation, suggesting that PSG-1 probably stimulated macrophage activities by activating the nuclear factor-κB pathway.