The stimulatory effect of HI 129, a novel indole derivative, on glucose-induced insulin secretion.

Indole derivatives exhibit a broad spectrum of beneficial effects, encompassing anti-inflammatory, antiviral, antimalarial, anti-diabetic, antioxidant, anti-hepatitis, and antidepressant properties. Here, we describe the potentiation of insulin secretion in pancreatic islets and INS-1 cells through methyl 2-(2-ethoxy-1-hydroxy-2-oxoethyl)-1-(pyrimidine-2-yl)-1H-indole-3-carboxylate (HI 129), a novel indole derivative. Treatment with HI 129 led to notably decreased ADP/ATP ratios in pancreatic islets and INS-1 cells compared to those in the vehicle-treated controls, indicating a shift in cellular ATP production. Moreover, the augmentation of insulin secretion by HI 129 was closely correlated with its ability to enhance the mitochondrial membrane potential and respiration, partly by reducing the phosphorylation levels of AMP-activated protein kinase (AMPK). Mechanistically, HI 129 enhanced the association between AMPK and ß-arrestin-1, critical molecules for glucose-induced insulin secretion. Furthermore, ß-arrestin-1 depletion attenuated the effect of HI 129 on glucose-induced insulin secretion, suggesting that HI 129 potentiates insulin secretion via ß-arrestin-1/AMPK signaling. These results collectively underscore the potential of HI 129 in enhancing insulin secretion as a novel candidate for improving glucose homeostasis in type 2 diabetes.

S6K1 deficiency in tumor stroma impairs lung metastasis of melanoma in mice.

Accumulating data suggest that ribosomal protein S6 kinase 1 (S6K1), an effector in the mammalian target of rapamycin (mTOR) pathway, plays pleiotropic roles in tumor progression. However, to date, while the tumorigenic function of S6K1 in tumor cells has been well elucidated, its role in the tumor stroma remains poorly understood. We recently showed that S6K1 mediates vascular endothelial growth factor A (VEGF-A) production in macrophages, thereby supporting tumor angiogenesis and growth. As macrophage-derived VEGF-A is crucial for both tumor cell intravasation and extravasation across the vascular endothelium, our previous findings suggest that stromal S6K1 signaling is required for tumor metastatic spread. Therefore, we aimed to determine the impact of host S6K1 depletion on tumor metastasis using a murine model of pulmonary metastasis (S6k1-/- mice implanted with B16F10 melanoma). The ablation of S6K1 in the host microenvironment significantly reduced the metastasized B16F10 melanoma cells on the lung surface in both spontaneous and intravenous lung metastasis mouse models without affecting the incidence of metastasis to distant lymph nodes. In addition, stromal S6K1 loss decreased the number of tumor cells circulating in the peripheral blood of mice bearing B16F10 xenografts without affecting the vascular leakage induced by VEGF-A in vivo. These observations demonstrate that S6K1 signaling in host cells other than endothelial cells is required to modulate the host microenvironment to facilitate the metastatic spread of tumors via blood circulation, thus revealing its novel role in the tumor stroma during tumor progression.

The Novel Inhibitory Effect of YM976 on Adipocyte Differentiation.

The pyrimidine derivative YM976 (4-(3-chlorophenyl)-1,7-diethylpyrido(2,3-d)-pyrimidin-2(1H)-one) exerts anti-inflammatory and anti-asthmatic effects. Considering that accumulation of lipids in adipose tissue is accompanied by inflammation, we investigated whether YM976 affects adipocyte differentiation. We found that YM976 significantly decreased lipid accumulation without cytotoxicity and reduced the expression levels of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα) as well as their lipogenic regulators including fatty acid synthase (FASN) and fatty acid-binding protein 4 (FABP4) in 3T3-L1 cells induced for differentiation. YM976 mainly inhibited the early stage of adipocyte differentiation. Furthermore, intracellular cAMP level was elevated by YM976 resulting in increased phosphorylation of adenosine monophosphate-activated protein kinase (AMPK). Conversely, decreasing the levels of AMPK or treatment with Compound C, an AMPK inhibitor, lessened the suppressive effects of YM976 on PPARγ transcriptional activity and adipogenesis. Thus, our results suggest YM976 as a novel potential compound for controlling lipid accumulation and formation of adipocytes in obesity.

Bioactive Phytochemicals from Salix pseudolasiogyne Twigs: Anti-Adipogenic Effect of 2'-O-Acetylsalicortin in 3T3-L1 Cells.

Salix pseudolasiogyne (Salicaceae) is a willow tree and has been used as a medicinal herb in Korea to treat pain and fever. As a part of an ongoing study to identify bioactive natural products, potential anti-adipogenic compounds were investigated using the ethanol (EtOH) extract of S. pseudolasiogyne twigs. Phytochemical investigation of the EtOH extracts using liquid chromatography-mass spectrometry (LC/MS) led to the separation of two compounds, oregonin (1) and 2'-O-acetylsalicortin (2). The structures of the isolates were identified using nuclear magnetic resonance spectroscopy and LC/MS analysis. To the best of our knowledge, it is the first report identifying oregonin (1) in twigs of S. pseudolasiogyne. Here, we found that the isolated compounds, oregonin (1) and 2'-O-acetylsalicortin (2), showed anti-adipogenic effects during 3T3-L1 cell differentiation. Notably, 2'-O-acetylsalicortin (2), at a concentration of 50 µM, significantly suppressed lipid accumulation. Moreover, the mRNA and protein levels of lipogenic and adipogenic transcription factors were reduced in 2'-O-acetylsalicortin (2)-treated 3T3-L1 cells. Taken together, these results indicate that 2'-O-acetylsalicortin (2), isolated from S. pseudolasiogyne twigs, has the potential to be applied as a therapeutic agent to effectively control adipocyte differentiation, a critical stage in the progression of obesity.

Anti-Adipogenic Effects of Salicortin from the Twigs of Weeping Willow (Salix pseudolasiogyne) in 3T3-L1 Cells.

Salix pseudolasiogyne (Salicaceae), the "weeping willow," has been used in traditional Korean medicine to treat pain and fever due to its high concentrations of salicylic acid and salicin. The present study investigated bioactive compounds from S. pseudolasiogyne twigs to discover bioactive natural products. Phytochemical investigation of the ethanol (EtOH) extract of S. pseudolasiogyne twigs followed by liquid chromatography-mass spectrometry (LC/MS)-based analysis led to the isolation of two salicin derivatives, salicortinol and salicortin, the structures of which were determined by interpretation of their NMR spectra and data from the LC/MS analysis. To the best of our knowledge, this is the first report of salicortinol isolated from S. pseudolasiogyne. The isolated compounds were evaluated for their anti-adipogenic effects in 3T3-L1 cells. Both salicortinol and salicortin were found to significantly inhibit adipocyte differentiation in 3T3-L1 cells. In particular, salicortin exhibited a strong inhibitory effect on lipid accumulation. Furthermore, salicortin inhibited the expression of lipogenic and adipogenic transcription factors, including FASN, FABP4, C/EBPα, C/EBPß, and PPARγ, without inducing cytotoxicity. These results suggest that salicortin could be a potential therapeutic compound for the prevention or treatment of metabolic disorders such as obesity.

Novel anti-adipogenic effect of CF3-allylated indole in 3T3-L1 cells.

Indole derivatives from various plants are known to have health benefits because of their anti-cancer, anti-oxidant, anti-inflammatory, and anti-tubercular effects. However, their effects on adipogenesis have not been fully elucidated yet. Herein, we show that a newly synthesized indole derivative, CF3-allylated indole, [(E)-1-(pyrimidin- 2-yl)-2-(4,4,4- trifluorobut-2-enyl)-1H-indole], effectively inhibits adipogenesis. We found that CF3-allylated indole inhibited lipid accumulation and suppressed the expression of CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator activated receptor γ (PPARγ) in 3T3-L1 cells. The inhibitory effect of CF3-allylated indole primarily occurred at the early phase of adipocyte differentiation by increasing intracellular cyclic adenosine monophosphate (cAMP) levels and enhancing protein kinase A (PKA) and adenosine monophosphate-activated protein kinase (AMPK) signaling. Conversely, depletion of PKA or treatment with a protein kinase A inhibitor (H89) reversed such inhibitory effects of CF3-allylated indole on adipogenesis and PPARγ expression. These results suggest that CF3-allylated indole inhibits early stages of adipogenesis by increasing phosphorylation of PKA/AMPK, leading to decreased expression of adipogenic genes in 3T3-L1 cells. These results indicate that CF3-allylated indole has potential for controlling initial adipocyte differentiation in metabolic disorders such as obesity.

Exosome-Mediated Differentiation of Mouse Embryonic Fibroblasts and Exocrine Cells into ß-Like Cells and the Identification of Key miRNAs for Differentiation.

Diabetes is a concerning health malady worldwide. Islet or pancreas transplantation is the only long-term treatment available; however, the scarcity of transplantable tissues hampers this approach. Therefore, new cell sources and differentiation approaches are required. Apart from the genetic- and small molecule-based approaches, exosomes could induce cellular differentiation by means of their cargo, including miRNA. We developed a chemical-based protocol to differentiate mouse embryonic fibroblasts (MEFs) into ß-like cells and employed mouse insulinoma (MIN6)-derived exosomes in the presence or absence of specific small molecules to encourage their differentiation into ß-like cells. The differentiated ß-like cells were functional and expressed pancreatic genes such as Pdx1, Nkx6.1, and insulin 1 and 2. We found that the exosome plus small molecule combination differentiated the MEFs most efficiently. Using miRNA-sequencing, we identified miR-127 and miR-709, and found that individually and in combination, the miRNAs differentiated MEFs into ß-like cells similar to the exosome treatment. We also confirmed that exocrine cells can be differentiated into ß-like cells by exosomes and the exosome-identified miRNAs. A new differentiation approach based on the use of exosome-identified miRNAs could help people afflicted with diabetes.

Loss of S6K1 But Not S6K2 in the Tumor Microenvironment Suppresses Tumor Growth by Attenuating Tumor Angiogenesis.

Two isoforms of the 70-kDa ribosomal protein S6 kinase, S6K1 and S6K2, have been identified and are considered key downstream effectors of the mTOR signaling pathway, which is involved in tumor growth and progression. However, their biological roles in the tumor microenvironment are poorly understood. In this study, utilizing tumor xenograft models in S6k1-/- and S6k2-/- mice, we show that loss of S6K1 but not S6K2 in the tumor stroma suppresses tumor growth, accompanied by attenuated tumor angiogenesis. We found that while S6K1 depletion had no effect on the proangiogenic phenotype of endothelial cells, the growth and angiogenesis of tumor xenografts were significantly reduced in wild-type mice upon reconstitution with S6K1-deficient bone marrow cells. Furthermore, upon S6K1 loss, induction of both mRNA and protein levels of Hif-1α and those of the downstream target, Vegf, was compromised in bone marrow-derived macrophages stimulated with lactate. These findings indicate that S6K1 but not S6K2 contributes to establishing a microenvironment that favors tumor growth through mediating angiogenesis, and suggest that attenuated tumor angiogenesis upon loss of S6K1 in the tumor stroma is, at least in part, attributable to impaired upregulation of Vegf in tumor-associated macrophages.

Carbamazepine Enhances Adipogenesis by Inhibiting Wnt/ß-catenin Expression.

Carbamazepine is a drug that is widely used in the treatment of epilepsy and bipolar disorder. The prevalence of obesity in patients treated with carbamazepine has been frequently reported. However, whether carbamazepine affects adipogenesis, one of the critical steps in the development of obesity, remains unclear. Here, we show that carbamazepine increased the expression levels of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein ß (C/EBPß), and fatty acid synthase (FASN) in 3T3-L1 cells. Notably, carbamazepine inhibited the expression levels of ß-catenin, a negative regulator of adipogenesis, leading to enhanced adipogenesis. Conversely, ß-catenin overexpression abolished the effect of carbamazepine on adipogenic gene expression. However, depletion of ß-catenin further enhanced PPARγ expression. In addition, carbamazepine reduced ß-catenin expression by lowering the levels of phospho-low density lipoprotein receptor-related protein 6 (p-LRP6) and phospho-glycogen synthase kinase 3ß (p-GSK3ß) in Wnt/ß-catenin signaling. Moreover, carbamazepine reduced Wnt mRNA expression and decreased the promoter activities of TCF, the target of ß-catenin during adipogenesis. These results suggest that carbamazepine enhances adipogenesis by suppressing Wnt/ß-catenin expression, indicating its potential effects on obesity-related metabolism.

Vacuolar H+-ATPase Subunit V0C Regulates Aerobic Glycolysis of Esophageal Cancer Cells via PKM2 Signaling.

The vacuolar H+-adenosine triphosphatase (ATPase) subunit V0C (ATP6V0C), a proton-conducting, pore-forming subunit of vacuolar ATPase, maintains pH homeostasis and induces organelle acidification. The intracellular and extracellular pH of cancer cells affects their growth; however, the role of ATP6V0C in highly invasive esophageal cancer cells (ECCs) remains unclear. In this study, we examined the role of ATP6V0C in glucose metabolism in ECCs. The ATP6V0C depletion attenuated ECC proliferation, invasion, and suppressed glucose metabolism, as indicated by reduced glucose uptake and decreased lactate and adenosine triphosphate (ATP) production in cells. Consistent with this, expression of glycolytic enzyme and the extracellular acidification rate (ECAR) were also decreased by ATP6V0C knockdown. Mechanistically, ATP6V0C interacted with pyruvate kinase isoform M2 (PKM2), a key regulator of glycolysis in ECCs. The ATP6V0C depletion reduced PKM2 phosphorylation at tyrosine residue 105 (Tyr105), leading to inhibition of nuclear translocation of PKM2. In addition, ATP6V0C was recruited at hypoxia response element (HRE) sites in the lactate dehydrogenase A (LDHA) gene for glycolysis. Thus, our data suggest that ATP6V0C enhances aerobic glycolysis and motility in ECCs.

Allicin induces beige-like adipocytes via KLF15 signal cascade.

Under specific conditions, white adipose tissue (WAT) depots are readily converted to a brown-like state, which is associated with weight loss. However, whether diet-derived factors directly induce browning of white adipocytes has yet to be established. Thus, we investigated the effects of allicin, one of the major components of garlic, on brown-like adipocyte formation in inguinal WAT (iWAT), and prevention of obesity and related complications in animal models. Allicin significantly increased mRNA and/or protein expression of brown adipocyte markers including uncoupling protein 1 (UCP1) in differentiated mouse embryonic fibroblast cell line 3T3-L1 and differentiated iWAT stromal vascular cells (SVC), suggesting that allicin induced brown-like adipocyte formation in vitro. Concomitantly, allicin markedly enhanced the protein expression of KLF-15 and its interaction with UCP-1 promoter region. Such changes were absent in cells lacking KLF-15, suggesting the critical role of KLF15 in allicin action. Allicin also induced brown-like adipogenesis in vivo along with the appearance of multilocular adipocytes, increased UCP1 expression and increased lipid oxidation. In summary, our data suggest that allicin potentially prevents obesity and associated metabolic disorders such as type 2 diabetes mellitus by enhancing the expression of brown adipocyte-specific genes, including UCP-1, through KLF15 signal cascade.

A single extra copy of Down syndrome critical region 1-4 results in impaired hepatic glucose homeostasis.

OBJECTIVES: During fasting, hepatic gluconeogenesis is induced to maintain energy homeostasis. Moreover, abnormal dysregulation of hepatic glucose production is commonly observed in type 2 diabetes. However, the signaling components controlling hepatic glucose production to maintain normal glucose levels are not fully understood. Here, we examined the physiological role of Down syndrome critical region 1-4 (DSCR1-4), an endogenous calcineurin signaling inhibitor in the liver that mediates metabolic adaptation to fasting. METHODS: We assessed the effect of cyclosporine A, an inhibitor of calcineurin signaling on gluconeogenic gene expression in primary hepatocytes. DSCR1-4 expression was examined in diet- and genetically-induced mouse models of obesity. We also investigated the metabolic phenotype of a single extra copy of DSCR1-4 in transgenic mice and how DSCR1-4 regulates glucose homeostasis in the liver. RESULTS: Treatment with cyclosporin A increased hepatic glucose production and gluconeogenic gene expression. The expression of DSCR1-4 was induced by refeeding and overexpressed in obese mouse livers. Moreover, transgenic mice with a single extra copy of DSCR1-4 exhibited pyruvate intolerance and impaired glucose homeostasis. Mechanistically, DSCR1-4 overexpression increased phosphorylation of the cAMP response element-binding protein, which led to elevated expression levels of gluconeogenic genes and, thus, enhanced hepatic glucose production during fasting. CONCLUSION: A single extra copy of DSCR1-4 results in dysregulated hepatic glucose homeostasis and pyruvate intolerance. Our findings suggest that nutrient-sensitive DSCR1-4 is a novel target for controlling hepatic gluconeogenesis in diabetes.

Association between nonalcoholic fatty liver disease and bone mineral density in postmenopausal women.

OBJECTIVE: Growing evidence suggests that nonalcoholic fatty liver disease (NAFLD) is associated with reduced bone mineral density (BMD). This study examined the association between NAFLD and BMD in postmenopausal Korean women. METHODS: This retrospective cross-sectional study analyzed 3739 postmenopausal women aged 50-59 years who visited a health promotion center for a routine checkup from 2009 to 2014. Menopause was defined as absence of menstruation for ≥12 months and an elevated follicle-stimulating hormone serum level (>20 IU/L). Women were excluded if they had a history of disease or use of medication that might affect bone metabolism. NAFLD was diagnosed by ultrasonography; BMD was measured by dual-energy X-ray absorptiometry. BMDs were compared according to the presence of NAFLD, and associations between NAFLD and BMD were analyzed after adjustment. RESULTS: Among 3739 postmenopausal women, 605 (16.2%) had NAFLD. Mean BMD at the lumbar spine (P = 0.017) and femur neck (P < 0.0001) was significantly lower in women with NAFLD than in those without NAFLD. Associations between NAFLD and BMD were significantly negative at both sites after adjusting for potential clinical confounders and factors which were significantly associated with BMD. CONCLUSIONS: NAFLD is negatively associated with BMD in postmenopausal women. A longitudinal study is recommended.

Trichostatin A resistance is facilitated by HIF-1α acetylation in HeLa human cervical cancer cells under normoxic conditions.

Trichostatin A (TSA) is an anticancer drug that inhibits histone deacetylases (HDACs). Hypoxia-inducible factor 1 (HIF-1) participates in tumor angiogenesis by upregulating target genes, such as vascular endothelial growth factor (VEGF). In the present study, we investigated whether TSA treatment increases HIF-1α stabilization via acetylation under normoxic conditions, which would lead to VEGF upregulation and resistance to anticancer drugs. TSA enhanced total HIF-1α and VEGF-HRE reporter activity under normoxic conditions. When cells were transfected with GFP-HIF-1α, treatment with TSA increased the number of green fluorescence protein (GFP)-positive cells. TSA also enhanced the nuclear translocation of HIF-1α protein, as assessed by immunoblotting and as evidenced by increased nuclear localization of GFP-HIF-1α. An increase in the interaction between HIF-1α and the VEGF promoter, which was assessed by a chromatin immunoprecipitation (ChIP) assay, led to activation of the VEGF promoter. TSA acetylated HIF-1α at lysine (K) 674, which led to an increase in TSA-induced VEGF-HRE reporter activity. In addition, TSA-mediated cell death was reduced by the overexpression of HIF-1α but it was rescued by transfection with a HIF-1α mutant (K674R). These data demonstrate that HIF-1α may be stabilized and translocated into the nucleus for the activation of VEGF promoter by TSA-mediated acetylation at K674 under normoxic conditions. These findings suggest that HIF-1α acetylation may lead to resistance to anticancer therapeutics, such as HDAC inhibitors, including TSA.

Growth differentiation factor 15 predicts advanced fibrosis in biopsy-proven non-alcoholic fatty liver disease.

BACKGROUND & AIMS: We explored whether growth differentiation factor 15 (GDF15) affects the histological severity of non-alcoholic fatty liver disease (NAFLD) independent of insulin resistance. METHODS: In a biopsy-proven NAFLD cohort, we measured serum GDF15 levels using enzyme-linked immunosorbent assays. RESULTS: Among 190 subjects (mean age, 53 ± 14 years; men, 52.1%), 72 (men, 65.3%) and 78 (men, 44.9%) were diagnosed with biopsy-proven non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH) respectively. GDF15 levels were significantly higher in NASH patients than in controls (P = .010) or NAFL patients (P = .001). Subjects with advanced fibrosis (≥F3) also showed higher GDF15 levels compared to the others (F0-2; P < .001). Among NAFLD patients, the highest quartile of GDF15 levels was significantly associated with a risk of advanced fibrosis even after adjustment for age, gender, body mass index, smoking status, hypertension, diabetes, aspartate aminotransferase, platelet, albumin, insulin resistance and low skeletal muscle mass (odds ratio, 4.27; 95% confidence interval, 1.04-17.63), but not with NASH risk. GDF15 levels showed a significant positive correlation with liver stiffness (Spearman's ρ, .525; P < .001). Palmitate treatment increased the GDF15 mRNA expression level significantly in Kupffer cells, but not in hepatocytes. In LX-2 cells, GDF15 treatment resulted in enhanced expression of α-smooth muscle actin and collagen I, as well as phosphorylation of SMAD2 and SMAD3. CONCLUSIONS: Our findings suggest that GDF15 may serve as a novel biomarker of advanced fibrosis in NAFLD, thereby indicating the need for urgent anti-fibrotic pharmacotherapy.

mTOR controls ChREBP transcriptional activity and pancreatic ß cell survival under diabetic stress.

Impaired nutrient sensing and dysregulated glucose homeostasis are common in diabetes. However, how nutrient-sensitive signaling components control glucose homeostasis and ß cell survival under diabetic stress is not well understood. Here, we show that mice lacking the core nutrient-sensitive signaling component mammalian target of rapamycin (mTOR) in ß cells exhibit reduced ß cell mass and smaller islets. mTOR deficiency leads to a severe reduction in ß cell survival and increased mitochondrial oxidative stress in chemical-induced diabetes. Mechanistically, we find that mTOR associates with the carbohydrate-response element-binding protein (ChREBP)-Max-like protein complex and inhibits its transcriptional activity, leading to decreased expression of thioredoxin-interacting protein (TXNIP), a potent inducer of ß cell death and oxidative stress. Consistent with this, the levels of TXNIP and ChREBP were highly elevated in human diabetic islets and mTOR-deficient mouse islets. Thus, our results suggest that a nutrient-sensitive mTOR-regulated transcriptional network could be a novel target to improve ß cell survival and glucose homeostasis in diabetes.

Sinigrin attenuates the progression of atherosclerosis in ApoE-/- mice fed a high-cholesterol diet potentially by inhibiting VCAM-1 expression.

Atherosclerosis is a complex inflammatory disease associated with elevated levels of atherogenic molecules for leukocyte recruitment. Sinigrin (2-propenylglucosinolate) is found mainly in broccoli, brussels sprouts, and black mustard seeds. Recently, sinigrin has received attention for its role in disease prevention and health promotion. In this study, we examined the effect of sinigrin on development of atherosclerosis in ApoE-/- mice and the expression of adhesion molecules in vascular smooth muscle cells (VSMCs). The serum concentrations of lactate dehydrogenase (LDH), triglyceride (TG), total cholesterol (TC), low density lipoprotein (LDL), calcium (Ca2+), and pro-inflammatory cytokines were reduced by sinigrin treatment in ApoE-/- mice. In addition, oral administration of sinigrin attenuated the mRNA expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), C-C motif chemokine ligand 2 (CCL2), and CCL5 on aorta tissues and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR), liver X receptor (LXR), sterol regulatory element-binding protein-2 (SREBP-2), and low density lipoprotein receptor (LDLR) on liver tissues in ApoE-/- mice. To provide a potential mechanism underlying the action of sinigrin, we evaluated the in vitro effect of sinigrin on the expression of the VCAM-1 in TNF-α-induced VSMCs. The increased expression of VCAM-1 by TNF-α stimulation was significantly suppressed by the treatment of sinigrin (1-100 µg/ml) and sinigrin inhibited the nuclear translocation of NF-κB and the phosphorylation of p38 MAPK and JNK pathways, suggesting that sinigrin decreases the TNF-α-stimulated VCAM-1 expression through the suppression of NF-κB and MAP kinases signaling pathways. Overall, sinigrin has the potential to be used in reducing the risks of atherosclerosis.

Synovial cell death is regulated by TNF-α-induced expression of B-cell activating factor through an ERK-dependent increase in hypoxia-inducible factor-1α.

B-cell activating factor (BAFF) has a role in the maturation and maintenance of B cells and is associated with rheumatoid arthritis (RA). Here, we investigated whether tumor necrosis factor (TNF)-α-induced BAFF expression controls the survival of fibroblast-like synoviocytes (FLS) and whether their survival can be regulated by TNF-α-mediated upregulation of hypoxia-inducible factor (HIF)-1α using MH7A synovial cells transfected with the SV40 T antigen. More TNF-α-treated cells died compared with the control. Survival was increased by incubation with Z-VAD but inhibited after transfection with BAFF-siRNA. Both BAFF and HIF-1α expression were enhanced when MH7A cells were treated with TNF-α. TNF-α-induced BAFF expression decreased in response to HIF-1α-siRNA, whereas it increased under hypoxia or by overexpressing HIF-1α. The HIF-1α binding site on the BAFF promoter (-693 to -688 bp) was confirmed by chromatin immunoprecipitation assay to detect the -750 to -501 bp and -800 to -601 bp regions. The BAFF promoter increased in response to TNF-α treatment or overexpression of HIF-1α. However, TNF-α-induced BAFF expression and promoter activity decreased after treatment with the ERK inhibitor PD98059. Cell death was enhanced by PD98059 but was inhibited by overexpression of HIF-1α. Taken together, our results demonstrate that BAFF expression to control synovial cell survival was regulated by HIF-1α binding to the BAFF promoter, and suggest for the first time that HIF-1α might be involved in the production of inflammatory cytokines to regulate the physiological function of rheumatic FLS.