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Oxidative cellular damage caused by free radicals is known to contribute to the pathogenesis of various diseases such as cancer, diabetes, and neurodegenerative diseases, as well as to aging. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and Kelch-like ECH-associated protein1 (Keap1) signaling pathways play an important role in preventing stresses including oxidative and inflammatory stresses. Nrf2 is a master regulator of cellular stress responses, induces the expression of antioxidant and detoxification enzymes, and protects against oxidative stress-induced cell damage. Glucagon-like peptide-1 (GLP-1) is an incretin hormone, which was originally found to increase insulin synthesis and secretion. It is now widely accepted that GLP-1 has multiple functions beyond glucose control in various tissues and organs including brain, kidney, and heart. GLP-1 and GLP-1 receptor agonists are known to be effective in many chronic diseases, including diabetes, via antioxidative mechanisms. In this review, we summarize the current knowledge regarding the role of GLP-1 in the protection against oxidative damage and the activation of the Nrf2 signaling pathway. [ABSTRACT FROM AUTHOR]

The extract of Psoralea corylifolia seeds (PCE) has been widely used as a herbal medicine because of its beneficial effect on human health. In this study, we investigated the protective effects and molecular mechanisms of PCE on palmitate- (PA-) induced toxicity in PC12 cells, a neuron-like cell line. PCE significantly increased cell viability in PA-treated PC12 cells and showed antiapoptotic effects, as evidenced by decreased expression of cleaved caspase-3, cleaved poly(ADP-ribose) polymerase, and bax protein as well as increased expression of bcl-2 protein. In addition, PCE treatment reduced PA-induced reactive oxygen species production and upregulated mRNA levels of antioxidant genes such as nuclear factor (erythroid-derived 2)-like 2 and heme oxygenase 1. Moreover, PCE treatment recovered the expression of autophagy marker genes such as beclin-1 and p62, which was decreased by PA treatment. Treatment with isopsoralen, one of the major components of PCE extract, also recovered the expression of autophagy marker genes and reduced PA-induced apoptosis. In conclusion, PCE exerts protective effects against lipotoxicity via its antioxidant function, and this effect is mediated by activation of autophagy. PCE might be a potential pharmacological agent to protect against neuronal cell injury caused by oxidative stress or lipotoxicity. [ABSTRACT FROM AUTHOR]

Glucagon-like peptide-1 (GLP-1) is an incretin hormone mainly secreted from intestinal L cells in response to nutrient ingestion. GLP-1 has beneficial effects for glucose homeostasis by stimulating insulin secretion from pancreatic beta-cells, delaying gastric emptying, decreasing plasma glucagon, reducing food intake, and stimulating glucose disposal. Therefore, GLP-1-based therapies such as GLP-1 receptor agonists and inhibitors of dipeptidyl peptidase-4, which is a GLP-1 inactivating enzyme, have been developed for treatment of type 2 diabetes. In addition to glucose-lowering effects, emerging data suggests that GLP-1-based therapies also show anti-inflammatory effects in chronic inflammatory diseases including type 1 and 2 diabetes, atherosclerosis, neurodegenerative disorders, nonalcoholic steatohepatitis, diabetic nephropathy, asthma, and psoriasis. This review outlines the anti-inflammatory actions of GLP-1-based therapies on diseases associated with chronic inflammation in vivo and in vitro, and their molecular mechanisms of anti-inflammatory action. [ABSTRACT FROM AUTHOR]

Exendin-4 (Ex-4), a peptide of glucagon-like peptide-1 receptor agonist, is a potent insulinotropic agent and alternative drug delivery systems to increase therapeutic utility have been explored. We developed exendin-4-encapsulated solid lipid nanoparticles (Eudragit Ex-4 SLNs) and compared the effects of Eudragit Ex-4 SLNs with those of native Ex-4 on INS-1 cells. We observed no significant toxic effects of nanoparticles at concentrations from 1 nM to 100 nM. Similar to Ex-4, Eudragit Ex-4 SLNs stimulated the production of cyclic AMP at 10 nM. Moreover, unlike treatment with the vehicle, treatment with 10 nM Eudragit Ex-4 SLNs increased insulin mRNA levels and insulin secretion. These insulinotropic effects of Eudragit Ex-4 SLNs were comparable to those of Ex-4. Thus, our in vitro results suggest that the biological effects of Eudragit Ex-4 SLNs are similar to those of Ex-4, and further in vivo pharmacokinetic studies are required to propose an alternative sustained release drug system. [ABSTRACT FROM AUTHOR]

Highlights: [•] We fabricated transparent indium-tin oxide electrodes (ITO) coated by parylene-C. [•] Adipose tissue-derived stem cells (ADSCs) were cultured on ITO electrode-based chip. [•] Impedance of ADSCs was affected by the age-related size and proliferation of cells. [•] Impedance measurement-based detection of the senescence of stem cells is possible. [ABSTRACT FROM AUTHOR]

Pancreatic β-cells produce and secrete insulin to maintain blood glucose levels within a narrow range. Defects in the function and mass of β-cells play a significant role in the development and progression of diabetes. Increased β-cell deficiency and β-cell apoptosis are observed in the pancreatic islets of patients with type 2 diabetes. At an early stage, β-cells adapt to insulin resistance, and their insulin secretion increases, but they eventually become exhausted, and the β-cell mass decreases. Various causal factors, such as high glucose, free fatty acids, inflammatory cytokines, and islet amyloid polypeptides, contribute to the impairment of β-cell function. Therefore, the maintenance of β-cell function is a logical approach for the treatment and prevention of diabetes. In this review, we provide an overview of the role of these risk factors in pancreatic β-cell loss and the associated mechanisms. A better understanding of the molecular mechanisms underlying pancreatic β-cell loss will provide an opportunity to identify novel therapeutic targets for type 2 diabetes. [ABSTRACT FROM AUTHOR]

More than 10 viruses have been reported to be associated with the development of type 1 diabetes-like symptoms in animals, with the best evidence coming from studies on the D variant of encephalomyocarditis (EMC-D) virus in mice and Kilham rat virus (KRV) in rats. A high titer of EMC-D viral infection results in the development of diabetes within 3 days, primarily due to the rapid destruction of β cells by viral replication within the cells. A low titer of EMC-D viral infection results in the recruitment of macrophages to the islets. Soluble mediators produced by activated macrophages play a critical role in the destruction of residual β cells. A single amino acid at position 776 of the EMC viral genome controls the diabetogenicity of the virus. In contrast, KRV causes autoimmune type 1 diabetes in diabetes-resistant BioBreeding (DR-BB) rats without direct infection of β cells. Macrophages play an important role in the development of diabetes in KRV-infected DR-BB rats. As well, KRV infection preferentially activates effector T cells, such as Th1-like CD45RC+CD4+ T cells and CD8+ T cells, and downregulates regulatory T cells, such as Th2-like CD45RC−CD4+ T cells. This results in the breakdown of the immune balance, contributing to the development of diabetes in KRV-infected DR-BB rats. [ABSTRACT FROM AUTHOR]

Abstract: Type 1 diabetes results from destruction of pancreatic β cells by β cell-specific autoreactive T cells in the nonobese diabetic (NOD) mouse. Defects in thymic negative selection are thought to result in failure to delete potential β cell-reactive T cells, contributing to the development of autoimmune diabetes. We investigated this possibility by comparing the deletion profile of double-positive (DP) thymocytes in NOD mice with diabetes-resistant strains of mice after anti-CD3 Ab treatment to trigger the TCR-mediated signaling pathway. We found that immature NOD CD4+CD8+ DP thymocytes have a lower activation threshold than C57BL/6 and Balb/c thymocytes. This was confirmed by showing that NOD DP thymocytes have a higher level of ERK and JNK phosphorylation. The low activation threshold of immature thymocytes resulted in rapid deletion of strongly activated immature DP thymocytes by negative selection, whereas weakly activated immature thymocytes differentiated more efficiently into CD69+CD3high DP thymocytes by positive selection. SP thymocytes, particularly CD4−CD8+ T cells that were efficiently generated from activated DP thymocytes, could induce severe insulitis and diabetes in NOD.scid mice. We conclude that the development of autoreactive diabetogenic T cells results from inordinate positive selection due to the low activation threshold of DP thymocytes in NOD mice. [Copyright &y& Elsevier]

Type 1 diabetes results from the loss of insulin-producing pancreatic β cells following the action of β-cell-specific autoimmune responses. One possible treatment for type 1 diabetes is the development of β-cell substitutes by introducing an insulin-producing gene into non-β cells, which would evade the β-cell-specific autoimmune attack. However, this approach has been hampered by the absence of (1) an appropriate glucose-sensing system to regulate insulin gene transcription; (2) enzymes that process proinsulin to insulin; and (3) glucose-regulatable exocytosis in the target cells. Recent attempts to solve these problems have sought new methods for effective gene transfer and have addressed issues such as the expression and release of insulin in response to the physiological stimulus of glucose, the production of biologically active insulin, and the selection of an ideal target cell for the expression of the insulin gene. [ABSTRACT FROM AUTHOR]

Polygonum multiflorum Thunb. (PM) root extracts have been used for treating graying hair in Oriental medicine; however, the molecular mechanisms underlying the melanogenic effects of PM root have not been fully understood. In the present study, we investigated the melanogenic effects of an ethanolic extract of PM root (PME) and the mechanisms involved. We examined the effects of PME on cell viability, cellular melanin content, and tyrosinase activity in B16F10 cells. The melanogenic mechanism of PME was explored using signaling inhibitors and examining the expression of melanogenic genes and signaling molecules by western blot and RT-qPCR analyses. PME did not exhibit any cytotoxicity in B16F10 cells compared to that in control cells. PME treatment significantly increased melanin production and tyrosinase activity. In addition, PME induced the expression of cyclooxygenase-2 (COX2) as well as that of melanogenic genes, such as microphthalmia-associated transcription factor (MiTF), tyrosinase-related protein (Trp) 1, Trp2, and tyrosinase, in B16F10 cells. PME treatment increased the level of phosphorylated p38 mitogen-activated protein kinase (MAPK), and pretreatment with SB 203580, a p38 MAPK inhibitor, significantly suppressed this PME-induced increase in the expression of COX2 and melanogenic genes. These results indicate that PME induced the expression of melanogenic genes by inducing COX2 expression via the activation of the p38 MAPK pathway, thereby contributing to the enhancement of melanogenesis. [ABSTRACT FROM AUTHOR]

Stem or progenitor cells are a potential source of insulin-producing cells, if methods can be found to reliably manipulate their differentiation. Glucagon-like peptide-1 (GLP-1) and its analog, exendin-4, axe known to induce differentiation of insulin-producing pancreatic β cells from different types of stem and progenitor cells. We previously found that when nonobese diabetic (NOD) mice were given a single intravenous injection of a recombinant adenovirus expressing GLP-1 (rAd-GLP-1), insulin-positive cells were detected not only in the pancreas, but also in the intestine. The present study investigated methods to promote the differentiation of intestinal stem cells to insulin-producing cells. An increased number of insulin-stained cells were observed in the intestine of NOD mice when rAd-GLP-1 was locally administered by intra-intestinal injection, as compared with systemic administration of rAd-GLP-1, suggesting that the intestinal stem cell pool might be a good source for differentiation into insulin-producing cells. Neurogenin (ngn)-3 is a transcription factor that responds to Notch signaling, and the expression of ngn-3 determines endocrine differentiation. When we examined the expression of ngn-3 and insulin by immunohistochemical staining in rAd-GLP-l-treated NOD mice, we detected expression of ngn-3 at 1 week after virus injection and insulin at 2 weeks after virus injection. As Notch signaling inhibits ngn-3 expression, we treated a segment of the small intestine (jejunum) from 8-week-old NOD mice with the Notch inhibitor, γ-secretase inhibitor, and exendin-4 alone or in combination and examined insulin mRNA expression. Treatment with a combination of γ-secretase inhibitor and exendin-4 showed additive effects on insulin mRNA expression as compared with treatment with either compound alone. We conclude that differentiation of intestinal stem cells into insulin-producing cells by exendin-4 in adult mice is mediated by ngn-3 expression and promoted by inhibition of Notch signaling. [ABSTRACT FROM AUTHOR]

Diabetic nephropathy (DN) is a major complication of diabetes mellitus. Psoralea corylifolia L. seed (PCS) is a traditional medicine effective against various diseases. In this study, we aimed to investigate the effect of bavachin, the major active component of PCS, on DN in db/db mice. Bavachin (10 mg/kg/day) was administered orally to 12-week-old male db/db mice for 6 wk. For in vitro experiments, SV40 MES13 cells were treated with bavachin in the presence of 25 mM glucose. Food and water intake and urine mass were significantly increased in db/db mice compared to wild-type CON mice, but bavachin administration significantly reduced these increases. Urinary microalbumin, blood urea nitrogen, and creatinine clearance which were significantly increased in db/db mice, were also decreased by bavachin administration. Glomerular area and collagen deposition in the kidney were significantly decreased in db/db mice following bavachin administration. Increased renal levels of fibrotic factors, fibronectin, COL1A1, and α-SMA, were reduced following bavachin administration. Protein expressions of antioxidant enzymes, namely SOD2, catalase, and HO-1, and mitochondrial function-related factors, namely SIRT1, PGC1α, Nrf1, and mtTFA, were reduced in the kidney tissues of db/db mice compared to wild-type CON mice, and bavachin administration upregulated these protein expressions. In vitro studies also showed that bavachin decreases mitochondria ROS production, increases the expression of PGC-1α and SIRT1, and decreases the expression of α-SMA in high glucose-treated SV40 MES13 cells. Based on these results, bavachin improved DN by inhibiting oxidative stress and enhancing mitochondrial function. [ABSTRACT FROM AUTHOR]

Podocyte damage and renal inflammation are the main features and pathogenesis of diabetic nephropathy (DN). Inhibition of lysophosphatidic acid (LPA) receptor 1 (LPAR1) suppresses glomerular inflammation and improves DN. Herein, we investigated LPA-induced podocyte damage and its underlying mechanisms in DN. We investigated the effects of AM095, a specific LPAR1 inhibitor, on podocytes from streptozotocin (STZ)-induced diabetic mice. E11 cells were treated with LPA in the presence or absence of AM095, and the expression of NLRP3 inflammasome factors and pyroptosis were measured. A chromatin immunoprecipitation assay and Western blotting were performed to elucidate underlying molecular mechanisms. Gene knockdown by transfecting small interfering RNA was used to determine the role of the transcription factor Egr1 (early growth response protein 1) and histone methyltransferase EzH2 (Enhancer of Zeste Homolog 2) in LPA-induced podocyte injury. AM095 administration inhibited podocyte loss, NLRP3 inflammasome factor expression, and cell death in STZ-induced diabetic mice. In E11 cells, LPA increased NLRP3 inflammasome activation and pyroptosis via LPAR1. Egr1 mediated NLRP3 inflammasome activation and pyroptosis in LPA-treated E11 cells. LPA decreased H3K27me3 enrichment at the Egr1 promoter in E11 cells by downregulating EzH2 expression. EzH2 knockdown further increased LPA-induced Egr1 expression. In podocytes from STZ-induced diabetic mice, AM095 suppressed Egr1 expression increase and EzH2/H3K27me3 expression reduction. Collectively, these results demonstrate that LPA induces NLRP3 inflammasome activation by downregulating EzH2/H3K27me3 and upregulating Egr1 expression, resulting in podocyte damage and pyroptosis, which may be a potential mechanism of DN progression. [ABSTRACT FROM AUTHOR]

Type 1 diabetes results from autoimmune-mediated pancreatic beta-cell destruction and transforming growth factor-beta (TGF-β) is known to play a preventive role in type 1 diabetes in non-obese diabetic (NOD) mice. In this study, we investigated the role of Smad4, a key molecule for Smad-dependent TGF-β signaling, in T cells of NOD mice in the pathogenesis of autoimmune diabetes. We generated T-cell-specific Smad4 knockout (Smad4 tKO) NOD mice and assessed the pathological and immunological changes. Smad4 tKO showed earlier onset and increased incidence of diabetes than wild type (WT) NOD mice. Pathological features such as insulitis, anti-glutamic acid decarboxylase auto-antibody levels and serum IFN-γ levels were significantly increased in Smad4 tKO compared with WT NOD mice. Proportion and number of activated/memory CD4+ T cell were significantly increased in pancreatic lymph nodes of Smad4 tKO compared with WT NOD mice. However, the proportion and function of regulatory T cells was not different. Effector CD4+ T cells from Smad4 tKO were more resistant to suppression by regulatory T cells than effector cells from WT NOD mice. The proliferative potential of effector T cells from Smad4 tKO was significantly elevated compared with WT NOD mice, and activation of sterol regulatory element binding protein-1c (SREBP-1c) in T cells of Smad4 tKO NOD mice was correlated with this proliferative activity. We conclude that Smad4 deletion in T cells of NOD mice accelerated the development of autoimmune diabetes and increased the incidence of the disease by dysregulation of T cell activation at least in part via SREBP-1c activation. [ABSTRACT FROM AUTHOR]

The production of reactive oxygen species (ROS) increases with aging and is associated with liver diseases. ChREBP is involved in lipogenic gene expression in hepatocytes, and we hypothesized that increases in ROS production would induce liver metabolic diseases via regulation of ChREBP expression. Mechanism studies were conducted using H 2 O 2 induced HepG2 cells and primary hepatocytes from old mouse. We detected increases in ChREBP expression, lipogenic gene (FAS and SCD1) expression, and intracellular triglyceride (TG) levels in H 2 O 2 -treated HepG2 cells, which were inhibited by ChREBP knockdown. ChREBP expression and intracellular TG levels were higher in primary hepatocytes from old mice than in those of young mice. Compared with old wild-type mice, intracellular TG levels were significantly reduced in primary hepatocytes from old ChREBP knockout mice. Furthermore, H 2 O 2 stimulation was found to induce HNF-4α expression in HepG2 cells and this expression was higher in primary hepatocytes from old mice. ChIP-qPCR assays indicated that binding of HNF-4α to ChREBP promoter was significantly increased by H 2 O 2 treatment in HepG2 cells. Further study revealed that H 2 O 2 -promoted increases in ChREBP expression and intracellular TG levels were significantly inhibited by HNF-4α knockdown. H 2 O 2 treatment also significantly increased ASK1 expression, whereas ASK1 knockdown inhibited H 2 O 2 -induced HNF-4α expression. Collectively, our data indicate that an increase in ROS production can induce HNF-4α expression via the ASK1 pathway and subsequently enhances the expression of ChREBP, thereby contributing to lipogenesis. This pathway may be involved in the elevated liver lipid levels associated with aging and oxidative stress. [ABSTRACT FROM AUTHOR]

The seeds of Psoralea corylifolia (PCS), also called "Boh-Gol-Zhee" in Korean, have been used in traditional medicine. PCS is effective for the treatment of vitiligo, cancer, inflammatory diseases, neurodegenerative diseases, kidney diseases, and musculoskeletal diseases. In this study, we validated the beneficial effects of PCS extract on dexamethasone (DEX)-induced muscle atrophy in mice. DEX (20 mg/kg/day, 10 days) was intraperitoneally injected into C57BL/6 male mice to induce muscular atrophy. Oral administration of PCS extract (200 or 500 mg/kg/day) was started 2 days before DEX injection and continued for 12 days. PCS extract inhibited DEX-induced decrease in body and muscle weight, grip strength, and cross-sectional area of the tibialis anterior. PCS extract significantly increased the mRNA and protein expression levels of myosin heavy chain 1, 2A, and 2X in DEX-administered mice. DEX administration significantly increased the levels of muscle atrophy factors atrogin-1, muscle RING-finger protein-1, and myostatin, which were inhibited by the PCS extract. Additionally, PCS extract increased the expression of muscle regeneration factors, such as myoblast determination protein 1, myogenin, and embryonic myosin heavy chain, and muscle synthesis markers, such as protein kinase B and mammalian target of rapamycin signaling molecules. PCS extract also significantly decreased the DEX-induced production of 4-hydroxynonenal, an oxidative stress marker. Furthermore, PCS extract recovered superoxide dismutase 2, glutathione peroxidase, and catalase activities, which were significantly reduced by DEX administration. Moreover, DEX-induced activation of nuclear factor kappa-light-chain-enhancer of activated B cells and expression of cytokines, such as tumor necrosis factor α and monocyte chemoattractant protein-1, significantly decreased after PCS extract administration. Here, we demonstrated that PCS extract administration protected against DEX-induced muscle atrophy. This beneficial effect was mediated by suppressing the expression of muscle degradation factors and increasing the expression of muscle regeneration and synthesis factors. This effect was probably due to the inhibition of oxidative stress and inflammation. These results highlight the potential of PCS extract as a protective and therapeutic agent against muscle dysfunction and atrophy. [Display omitted] • PCS extract increased grip strength and muscle fiber size in DEX-administered mice. • PCS extract treatment reduces the expression of muscle degradation factors. • PCS extract treatment increases the expression of myogenic factors. • PCS extract treatment exhibits antioxidative and anti-inflammatory effects. [ABSTRACT FROM AUTHOR]

The epithelial–mesenchymal transition (EMT) is a differentiation process associated with fibrogenesis in diabetic nephropathy (DN). Lysophosphatidic acid (LPA) is a small, naturally occurring glycerophospholipid implicated in the pathogenesis of DN. In this study, we investigated the role of LPA/LPAR1 signaling in the EMT of tubular cells as well as the underlying mechanisms. We observed a decrease in E-cadherin and an increase in vimentin expression levels in the kidney tubules of diabetic db/db mice, and treatment with ki16425 (LPAR1/3 inhibitor) inhibited the expression of these EMT markers. Ki16425 treatment also decreased the expression levels of the fibrotic factors fibronectin and alpha-smooth muscle actin (α-SMA) in db/db mice. Similarly, we found that LPA decreased E-cadherin expression and increased vimentin expression in HK-2 cells, which was reversed by treatment with ki16425 or AM095 (LPAR1 inhibitor). In addition, the expression levels of fibronectin and α-SMA were increased by LPA, and this effect was reversed by treatment with ki16425 and AM095 or by LPAR1 knockdown. Moreover, LPA induced the expression of the transcription factor, Krüppel-like factor 5 (KLF5), which was decreased by AM095 treatment or LPAR1 knockdown. The expression levels of EMT markers and fibrotic factors induced by LPA were decreased upon KLF5 knockdown in HK-2 cells. Inhibition of the extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and serine-threonine kinase (AKT) pathways decreased LPA-induced expression of KLF5 and EMT markers. In conclusion, these data suggest that LPA contributes to the pathogenesis of diabetic nephropathy by inducing EMT and renal tubular fibrosis via regulation of KLF5 through the LPAR1. [ABSTRACT FROM AUTHOR]

Background: Mesangial cell fibrosis, a typical symptom of diabetic nephropathy (DN), is a major contributor to glomerulosclerosis. We previously reported that the pharmacological blockade of lysophosphatidic acid (LPA) signaling improves DN. Although LPA signaling is implicated in diabetic renal fibrosis, the underlying molecular mechanisms remain unclear. Here, the role of carbohydrate-responsive element-binding protein (ChREBP) in LPA-induced renal fibrosis and the underlying mechanisms were investigated. Methods: Eight-week-old wild-type and db/db mice were intraperitoneally injected with the vehicle or an LPAR1/3 antagonist, ki16425 (10 mg/kg), for 8 weeks on a daily basis, following which the mice were sacrificed and renal protein expression was analyzed. SV40 MES13 cells were treated with LPA in the presence or absence of ki16425, and the expression of ChREBP and fibrotic factors, including fibronectin, TGF-β, and IL-1β, was examined. The role of ChREBP in the LPA-induced fibrotic response was investigated by ChREBP overexpression or knockdown. The involvement of Smad ubiquitination regulatory factor-2 (Smurf2), an E3 ligase, in LPA-induced expression of ChREBP and fibrotic factors was investigated by Smurf2 overexpression or knockdown. To identify signaling molecules regulating Smurf2 expression by LPA, pharmacological inhibitors such as A6370 (Akt1/2 kinase inhibitor) and Ly 294002 (PI3K inhibitor) were used. Results: The renal expression of ChREBP increased in diabetic db/db mice, and was reduced following treatment with the ki16425. Treatment with LPA induced the expression of ChREBP and fibrotic factors, including fibronectin, TGF-β, and IL-1β, in SV40 MES13 cells, which were positively correlated. The LPA-induced expression of fibrotic factors increased or decreased following ChREBP overexpression and knockdown, respectively. The production of reactive oxygen species (ROS) mediated the LPA-induced expression of ChREBP and fibrotic factors, and LPA decreased Smurf2 expression via Traf4-mediated ubiquitination. The LPA-induced expression of ubiquitinated-ChREBP increased or decreased following Smurf2 overexpression and knockdown, respectively. Additionally, Smurf2 knockdown significantly increased the expression of ChREBP and fibrotic factors. The pharmacological inhibition of Akt signaling suppressed the LPA-induced alterations in the expression of ChREBP and Smurf2. Conclusion: Collectively, the results demonstrated that the ROS/Akt-dependent downregulation of Smurf2 and the subsequent increase in ChREBP expression might be one of the mechanisms by which LPA induces mesangial cell fibrosis in DN. [ABSTRACT FROM AUTHOR]

Diabetic nephropathy is a microvascular complication of diabetes that is characterized by mesangial expansion and thickening of the glomerular basement membrane. The production of advanced glycation end products (AGEs) increases in diabetic patients. Activation of the receptor of AGE (RAGE) signaling pathway induces mesangial expansion via the reactive oxygen species (ROS)-mediated production of pro-inflammatory and extracellular matrix molecules. The Psoralea corylifolia L. seed (PCS) is a widely used herbal medicine with various biological activities. The current study investigated the effect of PCS extract on mesangial cell proliferation and the RAGE signaling pathway in SV40 MES 13 cells. SV40 MES 13 cells were harvested after treatment with various concentrations of PCS extract at 10 µg/ml AGEs for 24 h. The results revealed that the PCS extract inhibited AGEs-induced mesangial cell proliferation and cyclin protein expression in a concentration-dependent manner. In addition, the AGEs-induced expression of fibrotic factors, such as transforming growth factor β, fibronectin and collagen, was reduced in mesangial cells after exposure to the PCS extract. The PCS extract also reduced RAGE expression and inhibited the expression of its downstream signaling pathways, such as NADPH oxidase, intracellular ROS and phospho-NF-κB. In conclusion, the data suggested that the PCS extract attenuated AGEs-induced renal mesangial cell proliferation and fibrosis via the suppression of oxidative stress and the downregulation of inflammatory and fibrotic factor expression. [ABSTRACT FROM AUTHOR]

Type 2 diabetes is characterized by chronic hyperglycemia. Insulin, a hormone secreted from pancreatic β‐cells, decreases blood glucose levels, and glucagon, a hormone secreted from pancreatic α‐cells, increases blood glucose levels by counterregulation of insulin through stimulation of hepatic glucose production. In diabetic patients, dysregulation of glucagon secretion contributes to hyperglycemia. Thus, inhibition of the glucagon receptor is one strategy for the treatment of hyperglycemia in type 2 diabetes. In this paper, we report a series of biphenylsulfonamide derivatives that were designed, synthesized, and then evaluated by cAMP and hepatic glucose production assays as glucagon receptor antagonists. Of these, compound 7aB‐3 decreased glucagon‐induced cAMP production and glucagon‐induced glucose production in the in vitro assays. Glucagon challenge tests and glucose tolerance tests showed that compound 7aB‐3 significantly inhibited glucagon‐induced glucose increases and improved glucose tolerance. These results suggest that compound 7aB‐3 has therapeutic potential for the treatment of type 2 diabetes. [ABSTRACT FROM AUTHOR]

Type 1 diabetes mellitus is an autoimmune disease caused by the destruction of pancreatic beta cells. Many patients with type 1 diabetes experience skeletal muscle wasting. Although the link between type 1 diabetes and muscle wasting is not clearly known, insulin insufficiency and hyperglycemia may contribute to decreased muscle mass. In this study, we investigated the therapeutic effect of the ethanolic extract of Schisandrae chinensis Fructus (SFe) on muscle wasting in streptozotocin (STZ)-induced diabetic mice. STZ-diabetic C57BL/6 mice (blood glucose level ≥300 mg/dL) were orally administered SFe (250 or 500 mg/kg/day) for 6 weeks. We observed that SFe administration did not change blood glucose levels but increased gastrocnemius muscle weight, cross-sectional area, and grip strength in STZ-induced diabetic mice. Administration of SFe (500 mg/kg) decreased the expression of atrophic factors, such as MuRF1 and atrogin-1, but did not alter the expression of muscle synthetic factors. Further studies showed that SFe administration decreased the expression of KLF15 and p-CREB, which are upstream molecules of atrophic factors. Examination of the expression of molecules involved in autophagy–lysosomal pathways (e.g., p62/SQSTM1, Atg7, Beclin-1, ULK-1, LC3-I, and LC3-II) revealed that SFe administration significantly decreased the expression of p62/SQSTM1, LC3-I, and LC3-II; however, no changes were observed in the expression of Atg7, Beclin-1, or ULK-1. Our results suggest that SFe ameliorated muscle wasting in STZ-induced diabetic mice by decreasing protein degradation via downregulation of the CREB-KLF15-mediated UPS system and the p62/SQSTM1-mediated autophagy–lysosomal pathway. [ABSTRACT FROM AUTHOR]

Rho-associated kinases (ROCKs) have been reported to antagonize adipocyte differentiation, and inhibition of ROCKs by small molecules promotes adipogenesis. Surprisingly, our recent study revealed that the ROCK2-specific inhibitor KD025 (SLx-2119), suppresses differentiation at the intermediate stage in 3T3-L1 preadipocytes. To address whether the anti-adipogenic activity of KD025 is a generalizable property, we examined the effect of KD025 in human adipose-derived stem cells (hADSCs). KD025 significantly suppressed the adipocyte differentiation of hADSCs with downregulation of the protein and mRNA expression of various adipogenic and lipogenic markers, including PPARγ, C/EBPα, SREBP-1c, Glut4 and FABP4. Notably, we observed that adipocyte differentiation is effectively suppressed by exposure to KD025 during the mid-to-late period of adipogenesis but not at the earlier stages, showing stage-specificity. Contrary to expectations, KD025 upregulated the insulin signaling, as confirmed by the increased phosphorylation levels of Akt and GSK-3α/β, and the differentiation-promoting activity of insulin signaling was observed to be overwhelmed by the inhibitory activity. In addition, we observed that other ROCK inhibitors (Y-27632, fasudil, and H-1152P) did not suppress but promoted adipocyte differentiation. These results indicate that KD025 suppresses adipocyte differentiation by modulation of key factors activated at the intermediate stage of differentiation, and not by inhibition of ROCK2. [ABSTRACT FROM AUTHOR]

Diabetic nephropathy (DN) is one of the major long-term complications of diabetes. Lysophosphatidic acid (LPA) signaling has been implicated in renal fibrosis. In our previous study, we found that the LPA receptor 1/3 (LPAR1/3) antagonist, ki16425, protected against DN in diabetic db/db mice. Here, we investigated the effects of a specific pharmacological inhibitor of LPA receptor 1 (LPA1), AM095, on DN in streptozotocin (STZ)-induced diabetic mice to exclude a possible contribution of LPAR3 inhibition. AM095 treatment significantly reduced albuminuria and the albumin to creatinine ratio and significantly decreased the glomerular volume and tuft area in the treated group compared with the STZ-vehicle group. In the kidney of STZ-induced diabetic mice, the expression of LPAR1 mRNA and protein was positively correlated with oxidative stress. AM095 treatment inhibited LPA-induced reactive oxygen species production and NADPH oxidase expression as well as LPA-induced toll like receptor 4 (TLR4) expression in mesangial cells and in the kidney of STZ-induced diabetic mice. In addition, AM095 treatment suppressed LPA-induced pro-inflammatory cytokines and fibrotic factors expression through downregulation of phosphorylated NFκBp65 and c-Jun N-terminal kinases (JNK) in vitro and in the kidney of STZ-induced diabetic mice. Pharmacological or siRNA inhibition of TLR4 and NADPH oxidase mimicked the effects of AM095 in vitro. In conclusion, AM095 is effective in preventing the pathogenesis of DN by inhibiting TLR4/NF-κB and the NADPH oxidase system, consequently inhibiting the inflammatory signaling cascade in renal tissue of diabetic mice, suggesting that LPAR1 antagonism might provide a potential therapeutic target for DN. • AM095 improves kidney function in STZ-induced diabetic mice • AM095 reduces glomerular injury in the kidney of STZ-induced diabetic mice • AM095 suppresses reactive oxygen species production by down-regulating NADPH oxidase and TLR4 protein expression • AM095 suppresses proinflammatory cytokines and fibrotic factors expression by suppressing NF-κB and JNK signaling pathways [ABSTRACT FROM AUTHOR]

Highlights from the article: Compounds B 4 b and B 6 b were also effective in scavenging activity, with IC SB 50 sb values of 74.2 M and 96.6 M, respectively. Homoisoflavonoids B 1 b , B 2 b , B 5 b , and B 7 b showed the IC SB 50 sb value more than 100 M. For peroxynitrite from decomposition of SIN-1, B 3 b exhibited the strongest scavenging activity with IC SB 50 sb value of 44.0 M. The scavenging activities of other homoisoflavonoids were decreased in the following orders: B 4 b (47.2 M) > B 6 b (54.2 M) > B 1 b (79.4 M) > B 7 b (87.5 M) > B 2 b , B 5 b (>100 M). The scavenging activities were represented in the following order: B 3 b > B 4 b > B 1 b > B 6 b > B 7 b . Compounds B 6 b and B 7 b exerted the good inhibitory effect of growth against AGS cells, with IC SB 50 sb values of 41.4 and 85.7 M, respectively.

Diabetic nephropathy is one of the most serious complications of diabetes. Lipotoxicity in glomerular mesangial cells is associated with the progression of diabetic nephropathy. Paper mulberry, Broussonetia kazinoki Siebold (BK), has been used in oriental medicine for human health problems. However, to date, the beneficial effect of BK fruit has not been studied. In this study, we investigated the protective effect of an ethanolic extract of BK fruit (BKFE) against palmitate- (PA-) induced toxicity in mesangial cells. BKFE significantly increased the viability of PA-treated SV40 MES13 cells. BKFE significantly inhibited PA-induced apoptosis and decreased the expression of apoptotic genes, cleaved caspase-3, and cleaved PARP. Moreover, BKFE inhibited the expression of endoplasmic reticulum (ER) stress-related genes, such as BiP, phosphorylated eIF2α, cleaved ATF6, and spliced XBP-1, in PA-treated SV40 MES13 cells. BKFE decreased PA-induced ROS production. In addition, BKFE activated the transcription factor Nrf2 and increased the expression of antioxidant enzymes. However, knockdown of Nrf2 using siRNA suppressed this BKFE-induced increase in antioxidant enzyme expression. Furthermore, the protective effect of BKFE on PA-induced apoptosis was significantly reduced by Nrf2 knockdown. In conclusion, BKFE induced the expression of antioxidant enzymes via activation of Nrf2 and protected against PA-induced lipotoxicity in mesangial cells. [ABSTRACT FROM AUTHOR]

Glucagon-like peptide 1 (GLP-1) can increase pancreatic β-cells, and α-cells could be a source for new β-cell generation. We investigated whether GLP-1 increases β-cells through α-cell transdifferentiation. New β-cells originating from non-β-cells were significantly increased in recombinant adenovirus expressing GLP-1 (rAd-GLP-1)-treated RIP-CreER;R26-YFP mice. Proliferating α-cells were increased in islets of rAd-GLP-1-treated mice and αTC1 clone 9 (αTC1-9) cells treated with exendin-4, a GLP-1 receptor agonist. Insulin+glucagon+ cells were significantly increased by rAd-GLP-1 or exendin-4 treatment in vivo and in vitro. Lineage tracing to label the glucagon-producing α-cells showed a higher proportion of regenerated β-cells from α-cells in rAd-GLP-1-treated Glucagon-rtTA;Tet-O-Cre;R26-YFP mice than rAd producing β-galactosidase-treated mice. In addition, exendin-4 increased the expression and secretion of fibroblast growth factor 21 (FGF21) in αTC1-9 cells and β-cell-ablated islets. FGF21 treatment of β-cell-ablated islets increased the expression of pancreatic and duodenal homeobox-1 and neurogenin-3 and significantly increased insulin+glucagon+ cells. Generation of insulin+glucagon+ cells by exendin-4 was significantly reduced in islets transfected with FGF21 small interfering RNA or islets of FGF21 knockout mice. Generation of insulin+ cells by rAd-GLP-1 treatment was significantly reduced in FGF21 knockout mice compared with wild-type mice. We suggest that GLP-1 has an important role in α-cell transdifferentiation to generate new β-cells, which might be mediated, in part, by FGF21 induction. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Design and synthesis of novel GCGR antagonists as pyrimidine derivatives. • The compound of (R) -7a decreased the glucagon-induced cAMP production. • The compound of (R) -7a decreased the glucagon-induced glucose production. • The compound of (R) -7a decreased the glucagon-induced glucose excursion in vivo. • The compound of (R) -7a lowering fasting blood glucose levels in db / db mice. Abstract The hormone glucagon increases blood glucose levels through increasing hepatic glucose output. In diabetic patients, dysregulation of glucagon secretion contributes to hyperglycemia. Thus, the inhibition of glucagon receptor is one target for the treatment of hyperglycemia in type 2 diabetes. Here we designed and synthesized a series of small molecules based on phenylpyrimidine. Of these, the compound (R) -7a most significantly decreased the glucagon-induced cAMP production and glucagon-induced glucose production during in vitro and in vivo assays. In addition, (R) -7a showed good efficacy in glucagon challenge tests and lowered blood glucose levels in diabetic db/db mice. Our results suggest that the compound (R) -7a could be a potential glucose-lowering agent for treating type 2 diabetes. [ABSTRACT FROM AUTHOR]

Inflammation markers in zebrafish embryos reflect a toxic response that is common to other animal models and humans. Free fatty acids (FFAs) are known to cause damage in various tissues by inducing inflammation. In this study, we investigated whether a FFA (palmitate) induces inflammation in zebrafish embryos. Nitrous oxide (NO) production and cyclooxygenase-2 (COX-2) mRNA expression were increased in palmitate-treated zebrafish embryos in a dose-dependent manner. mRNA expression of pro-inflammatory cytokines, interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF- α), were also increased. Additionally, the mRNA expression of p65 nuclear factor-kB and I-kB-α were significantly increased after palmitate-treatment. Increased reactive oxygen species (ROS) expression was observed in palmitate-treated zebrafish embryos as well as pericardial edema. Additionally, mRNA expression of pro-inflammatory cytokines were increased in zebrafish liver and pancreas fed with palmitate-contained diet. Taken together, these results indicated that palmitate increases pro-inflammatory mediators in zebrafish embryos, suggesting that zebrafish could be an alternative animal model for inflammatory disease including diabetes. [ABSTRACT FROM AUTHOR]

Liquiritigenin (LQ) is a major active component of licorice root, which is a flavone used for treating many diseases, including diabetes. LQ has been shown to exhibit a glucose-lowering effect in diabetic mice. Therefore, we investigated the potential of LQ to protect against lipotoxicity-induced beta-cell apoptosis and the underlying molecular mechanisms. Exposure of INS-1 rat insulinoma cells to LQ significantly increased cell viability and blocked palmitate (PA)-induced apoptosis, as evidenced by the reduction of Annexin-V-stained cells, cleaved caspase-3 levels, and poly (ADP-ribose) polymerase (PARP) activity, as well as upregulation of Bcl-2 expression. Moreover, LQ treatment significantly reduced the endoplasmic reticulum (ER) stress response by reducing phosphorylated protein kinase RNA-like endoplasmic reticulum kinase (PERK), phosphorylated eIF-2a, and CHOP expression in PA-treated INS-1 cells. The anti-apoptotic effect of LQ treatment was reversed through co-treatment with fulvestrant, a specific inhibitor of the estrogen receptor. LQ also increased AKT phosphorylation, and inactivation of this molecular event failed to decrease PERK phosphorylation with LQ treatment in PA-treated INS-1 cells. This effect was further accompanied by an inability to recover cell viability. These results suggest that LQ protects INS-1 cells from lipotoxicity-induced apoptosis by suppressing ER stress. We conclude that estrogen receptor-mediated AKT phosphorylation is one of the mechanisms contributing to the anti-apoptotic effect of LQ. [ABSTRACT FROM AUTHOR]

Objective: β-Cell dysfunction plays a central role in the pathogenesis of type 2 diabetes (T2D), and the identification of novel approaches to improve β-cell function is essential to treat this disease. Baicalein, a flavonoid originally isolated from the root of Scutellaria Baicalensis, has been shown to have beneficial effects on β-cell function. Here, the authors investigated the molecular mechanism responsible for the protective effects of baicalein against palmitate (PA)-induced impaired β-cell function, and placed focus on the role of heme oxygenase (HO)-1. Methods: Rat pancreatic β-cell line INS-1 cells or mouse pancreatic islets were cultured with PA (500 μM) to induce lipotoxicity in the presence or absence of baicalein (50 μM), and the expressions of the ER stress markers, ATF-3, CHOP and GRP78 were detected by Western blotting and/or qPCR. The involvement of HO-1 was evaluated by HO-1 siRNA transfection and using the HO-1 inhibitor ZnPP. Results: Baicalein reduced PA-induced ER stress and inflammation and enhanced insulin secretion, and these effects were associated with the induction of HO-1. Furthermore, these protective effects were attenuated by ZnPP and by HO-1 siRNA. Pretreatment of PD98059 (an ERK inhibitor) significantly inhibited the protective effects of baicalein and blocked HO-1 induction. On the other hand, CO production by RuCO (a CO donor) ameliorated PA-induced ER stress, suggesting that CO production followed by HO-1 induction may contribute to the protective effects of baicalein against PA-induced β-cell dysfunction. Conclusion: Baicalein protects pancreatic β-cells from PA-induced ER stress and inflammation via an ERK-HO-1 dependent pathway. The authors suggest HO-1 induction in pancreatic β-cells appears to be a promising therapeutic strategy for T2D. [ABSTRACT FROM AUTHOR]

Background: Diminished wound healing is a major complication of diabetes mellitus and can lead to foot ulcers. However, there are limited therapeutic methods to treat this condition. Exendin-4 (Ex-4), a glucagon-like peptide-1 receptor agonist, is known to have many beneficial effects on diabetes. In addition, mesenchymal stem cells are known to have wound healing effects. We investigated the effects of Ex-4 in combination with human adipose tissue-derived stem cells (ADSCs) on diabetic wound healing in a diabetic animal model.Methods: Diabetic db/db (blood glucose levels, >500 mg/dl) or C57BL/6 mice were subjected to wounding on the skin of the back. One day after wounding, each wound received ADSCs (2.5 × 105 cells) injected intradermally around the wound and/or Ex-4 (50 μl of 100 nM Ex-4) topically applied on the wound with a fine brush daily. Wound size was monitored and wound histology was examined. Human endothelial cells and keratinocyte cells were used to assess angiogenesis and vascular endothelial growth factor expression in vitro.Results: Topical administration of Ex-4 or injection of ADSCs resulted in a rapid reduction of wound size in both diabetic and normoglycemic animals compared with vehicle treatment. Histological analysis also showed rapid skin reconstruction in Ex-4-treated or ADSC-injected wounds. A combination of Ex-4 and ADSCs showed a significantly better therapeutic effect over either treatment alone. In vitro angiogenesis assays showed that both Ex-4 and ADSC-conditioned media (CM) treatment improved migration, invasion and proliferation of human endothelial cells. ADSC-CM also increased migration and proliferation of human keratinocytes. In addition, both Ex-4 and ADSC-CM increased the expression of vascular endothelial growth factor. Co-culture with ADSCs increased migration and proliferation of these cells similar to that found after ADSC-CM treatment.Conclusions: We suggest that Ex-4 itself is effective for the treatment of diabetic skin wounds, and a combination of topical treatment of Ex-4 and injection of ADSCs has a better therapeutic effect. Thus, a combination of Ex-4 and ADSCs might be an effective therapeutic option for the treatment of diabetic wounds, such as foot ulcers. [ABSTRACT FROM AUTHOR]

Oxidative stress in pancreatic beta cells can inhibit insulin secretion and promote apoptotic cell death. Exendin-4 (EX4), a glucagon-like peptide-1 receptor agonist, can suppress beta cell apoptosis, improve beta cell function and protect against oxidative damage. In this study, we investigated the molecular mechanisms for antioxidative effects of EX4 in pancreatic beta cells. INS-1 cells, a rat insulinoma cell line, were pretreated with EX4 and exposed to palmitate or H 2 O 2 . Reactive oxygen species (ROS) production, and glutathione and insulin secretion were measured. The mRNA and protein expression levels of antioxidant genes were examined. The level of nuclear factor erythroid 2-related factor 2 (Nrf2), its binding to antioxidant response element ( ARE ), and its ubiquination in the presence of EX4 were determined. The Nrf2 signaling pathway was determined using rottlerin (protein kinase [PK]Cδ inhibitor), H89 (PKA inhibitor) and LY294002 (phosphatidylinositide 3-kinase [PI3K] inhibitor). EX4 treatment decreased ROS production, recovered cellular glutathione levels and insulin secretion in the presence of oxidative stress in INS-1 cells. The expression levels of glutamate-cysteine ligase catalytic subunit and heme oxygenase-1 were increased by EX4 treatment. EX4 promoted Nrf2 translocation, ARE binding activity and enhanced stabilization of Nrf2 by inhibition of ubiquitination. Knockdown of Nrf2 abolished the effect of EX4 on increased insulin secretion. Inhibition of PKCδ attenuated Nrf2 translocation and antioxidative gene expression by EX4 treatment. We suggest that EX4 activates and stabilizes Nrf2 through PKCδ activation, contributing to the increase of antioxidant gene expression and consequently improving beta cell function in the presence of oxidative stress. [ABSTRACT FROM AUTHOR]

Psoriasis is a chronic inflammatory skin disease and lysophosphatidic acid (LPA) has recently been reported to contribute to its pathogenesis through keratinocyte proliferation. In this study, we investigated the metabolic changes in the LPA-induced keratinocyte hyperproliferation and underlying mechanisms. HaCaT or HEKa cells were treated with LPA in the presence or absence of various chemical inhibitors. The glycolysis stress was measured using the Seahorse extracellular flux analyzer. Gene knockdown by siRNA transfection was used to investigate the role of LPAR1, PGAM1, and HIF-1α in LPA-induced metabolic changes. We confirmed the expression of PGAM1 and HIF-1α in imiquimod (IMQ)-induced psoriasis-like BALB/c mice. LPA increased aerobic glycolysis; however, treatment with ki16425, or LPAR1 knockdown inhibited LPA-induced glycolysis in HaCaT cells. LPA increased the expression of glycolytic enzyme PGAM1 through LPAR1. PGAM1 knockdown in HaCaT cells suppressed LPA-induced cell proliferation, changes in cell cycle factor expression, and inhibited LPA-induced aerobic glycolysis. LPA sequentially activated AKT, mTOR, its downstream target, p70 S6K, and increased HIF-1α expression through LPAR1. HIF-1α knockdown inhibited LPA-induced PGAM1 expression and aerobic glycolysis. A6730 also decreased LPA-induced activation of mTOR and p70 S6K and LPA-induced increases in HIF-1α and PGAM1 expression. Ki16425 suppressed the increased expression of PGAM1 and HIF-1α in the lesions of IMQ-induced psoriasis-like mice. In primary keratinocytes, LPA/LPAR1 signaling also induced AKT-mediated aerobic glycolysis. Collectively, the results demonstrated that LPA induces aerobic glycolysis via AKT/mTOR/HIF-1α-dependent PGAM1 expression during keratinocytes proliferation and this might be one of the mechanisms of psoriasis development. [ABSTRACT FROM AUTHOR]

Disuse muscle atrophy is characterized by a decrease in muscle mass and strength and an increase in glycolytic muscle fiber type. Although Schisandra chinensis extract has beneficial effects on muscle atrophy induced by various conditions (e.g., dexamethasone and aging), the effect of gomisin G, a lignan component of S. chinensis , on disuse muscle atrophy is unclear. Here, we induced disuse muscle atrophy through wire immobilization of the hind legs in mice followed by the oral administration of gomisin G. The cross-sectional area and muscle strength in disuse muscle atrophic mice were increased by gomisin G; however, the total muscle mass did not increase. Gomisin G decreased the expression of muscle atrophic factors (myostatin, atrogin-1, and MuRF1) but increased the expression of protein synthesis factors (mTOR and 4E-BP1). In H 2 O 2 -treated C2C12 myotubes, the level of puromycin incorporation (as a marker of protein synthesis) gradually increased in a dose-dependent manner by gomisin G. Furthermore, gomisin G induced a muscle fiber switch from fast-type glycolytic fibers (type 2B) to slow-type oxidative fibers (type I, 2A) in the gastrocnemius (GA) muscle as proved a decrease in the expression of TnI-FS and an increase in the expression of TnI-SS. Gomisin G increased mitochondrial DNA content and ATP levels in the GA muscle and COX activity in H 2 O 2 -treated C2C12 myotubes, improving mitochondrial function. Mechanistically, mitochondrial biogenesis is regulated by gomisin G via the Sirt 1/PGC-1α signaling pathway, targeting NRF1 and TFAM. These data suggest that gomisin G has a potential therapeutic effect on disuse muscle atrophy. [Display omitted] • Gomisin G improves grip strength in disuse muscle atrophic mice. • Gomisin G increases muscle synthesis rate in H2O2-treated C2C12 myotubes. • Gomisin G increases slow-type oxidative fiber contents in muscle of disuse mice. • Gomisin G induces mitochondrial biogenesis via the Sirt 1/PGC-1α signaling pathway. [ABSTRACT FROM AUTHOR]

Type 2 diabetes is caused by both insulin resistance and relative insulin deficiency. To investigate age-related changes in glucose metabolism and development of type 2 diabetes, we compared glucose homeostasis in different groups of C57BL/6J mice ranging in age from 4 months to 20 months (4, 8, 12, 16 and 20 months). Interestingly, we observed that non-fasting glucose levels were not significantly changed, but glucose tolerance gradually increased by 20 months of age, whereas insulin sensitivity declined with age. We found that the size of islets and glucose-stimulated insulin secretion increased with aging. However, mRNA expression of pancreatic and duodenal homeobox 1 and granuphilin was decreased in islets of older mice compared with that of 4-month-old mice. Serum calcium (Ca2+) levels were significantly decreased at 12, 20 and 28 months of age compared with 4 months and calcium sensing receptor (CaSR) mRNA expression in the islets significantly increased with age. An extracellular calcium depletion agent upregulated CaSR mRNA expression and consequently enhanced insulin secretion in INS-1 cells and mouse islets. In conclusion, we suggest that decreased Ca2+ levels and increased CaSR expression might be involved in increased insulin secretion to compensate for insulin resistance in aged mice. [ABSTRACT FROM AUTHOR]

G protein-coupled receptor (GPR) 119 is expressed in pancreatic β-cells and intestinal L cells, and is involved in glucose-stimulated insulin secretion and glucagon-like peptide-1 (GLP-1) release, respectively. Therefore, the development of GPR119 agonists is a potential treatment for type 2 diabetes. We screened 1500 natural plant extracts for GPR119 agonistic actions and investigated the most promising extract, that from Angelica dahurica (AD), for hypoglycemic actions in vitro and in vivo. Human GPR119 activation was measured in GeneBLAzer T-Rex GPR119-CRE-bla CHO-K1 cells; intracellular cAMP levels and insulin secretion were measured in INS-1 cells; and GLP-1 release was measured in GLUTag cells. Glucose tolerance tests and serum plasma insulin levels were measured in normal C57BL6 mice and diabetic db/db mice. AD extract-treated cells showed significant increases in GPR119 activation, intracellular cAMP levels, GLP-1 levels and glucose-stimulated insulin secretion as compared with controls. In normal mice, a single treatment with AD extract improved glucose tolerance and increased insulin secretion. Treatment with multiple doses of AD extract or n-hexane fraction improved glucose tolerance in diabetic db/db mice. Imperatorin, phellopterin and isoimperatorin were identified in the active fraction of AD extract. Among these, phellopterin activated GPR119 and increased active GLP-1 and insulin secretion in vitro and enhanced glucose tolerance in normal and db/db mice. We suggest that phellopterin might have a therapeutic potential for the treatment of type 2 diabetes. [ABSTRACT FROM AUTHOR]

Sensitive and selective determination of protein biomarkers remains a significant challenge due to the existence of various biomarkers in human body at a low concentration level. Therefore, new technologies were incessantly steered to detect tiny biomarkers at a low concentration level, yet, it is difficult to develop reliable, stable and sensitive detection methods for disease diagnostics. Therefore, the present study demonstrates a methodology to detect insulin in serum at low levels based on Ag nanoflower (AgNF) decorated reduced graphene oxide (rGO) modified micro-disk electrode arrays (MDEAs). The morphology of AgNF-rGO composite was characterized by scanning electron microscopy, the structure was analyzed using X-ray diffraction patterns and Raman spectra. The hybrid interface exhibited enhanced electrical conductivity when compared with its individual elements and had improved capturing ability for antibody–antigen binding towards insulin detection. In order to measure quantitatively the insulin concentration in PBS and human serum, the change in impedance (ΔZ) from electrochemical impedance spectroscopy was analyzed for various concentrations of insulin in [Fe(CN) 6 ] 3−/4− redox couple. The electrode with adsorbed antibodies showed an increase in ΔZ for the addition of antigen concentrations over a working range of 1–1000 ng mL −1 . The detection limits were 50 and 70 pg mL −1 in PBS and human serum, respectively. [ABSTRACT FROM AUTHOR]

11β-Hydroxysteroid dehydrogenase type 1 (11βHSD1) has been targeted for new drugs to treat type 2 diabetes and metabolic syndrome. In this study, we determined whether the inhibition of 11βHSD1 with a new selective inhibitor, SKI2852, could improve lipid profiles, glucose levels, and insulin sensitivity in type 2 diabetic and obese conditions. SKI2852 showed a potent inhibition of cortisone to cortisol conversion for over 80% in both liver and adipose tissue ex vivo from orally administered C57BL/6 mice, and in vivo analysis results were consistent with this. Repeated oral administrations of SKI2852 in diet-induced obesity (DIO) and ob / ob mice revealed a partially beneficial effect of SKI2852 in improving levels of cholesterols, triglycerides, free fatty acids, postprandial glucose, and/or blood hemoglobinA 1c . SKI2852 significantly reduced body weight increase in ob / ob mice, and efficiently suppressed hepatic mRNA levels of gluconeogenic enzymes in DIO mice. Moreover, SKI2852 enhanced hepatic and whole body insulin sensitivities in hyperinsulinemic-euglycemic clamp experiment in DIO mice. In conclusion, these results indicate that selective and potent inhibition of 11βHSD1 by SKI2852, thus blockade of active glucocorticoid conversion, may improve many aspects of metabolic parameters in type 2 diabetes and metabolic diseases, mainly by inhibitions of hepatic gluconeogenesis and partial improvements of lipid profiles. Our study strongly support that SKI2852 may have a great potential as a novel candidate drug for the treatment of diabetes and metabolic diseases. [ABSTRACT FROM AUTHOR]

We found that administration of a recombinant adenovirus (rAd) expressing betacellulin (BTC) into obese diabetic db/db mice ameliorated hyperglycemia. Exogenous glucose clearance was significantly improved, and serum insulin levels were significantly higher in rAd-BTC-treated mice than rAd-β-gal-treated control mice. rAd-BTC treatment increased insulin/bromodeoxyuridine double-positive cells in the islets, and islets from rAd-BTC-treated mice exhibited a significant increase in the level of G1-S phase-related cyclins as compared with control mice. In addition, BTC treatment increased messenger RNA (mRNA) and protein levels of these cyclins and cyclin-dependent kinases in MIN-6 cells. BTC treatment induced intracellular Ca levels through phospholipase C-γ1 activation, and upregulated calcineurin B (CnB1) levels as well as calcineurin activity. Upregulation of CnB1 by BTC treatment was observed in isolated islet cells from db/db mice. When treated with CnB1 small interfering RNA (siRNA) in MIN-6 cells and isolated islets, induction of cell cycle regulators by BTC treatment was blocked and consequently reduced BTC-induced cell viability. As well as BTC's effects on cell survival and insulin secretion, our findings demonstrate a novel pathway by which BTC controls beta-cell regeneration in the obese diabetic condition by regulating G1-S phase cell cycle expression through Ca signaling pathways. Key messages: [ABSTRACT FROM AUTHOR]

Ginseng has beneficial effects in cancer, diabetes and aging. There are two main varieties of ginseng: Panax ginseng (Korean ginseng) and Panax quinquefolius (American ginseng). There are anecdotal reports that American ginseng helps reduce body temperature, whereas Korean ginseng improves blood circulation and increases body temperature; however, their respective effects on body temperature and metabolic parameters have not been studied. We investigated body temperature and metabolic parameters in mice using a metabolic cage. After administering ginseng extracts acutely (single dose of 1000 mg/kg) or chronically (200 mg/kg/day for four weeks), core body temperature, food intake, oxygen consumption and activity were measured, as well as serum levels of pyrogen-related factors and mRNA expression of metabolic genes. Acute treatment with American ginseng reduced body temperature compared with PBS-treated mice during the night; however, there was no significant effect of ginseng treatment on body temperature after four weeks of treatment. 2, 2, food intake, activity and energy expenditure were unchanged after both acute and chronic ginseng treatment compared with PBS treatment. In acutely treated mice, serum thyroxin levels were reduced by red and American ginseng, and the serum prostaglandin E2 level was reduced by American ginseng. In chronically treated mice, red and white ginseng reduced thyroxin levels. We conclude that Korean ginseng does not stimulate metabolism in mice, whereas a high dose of American ginseng may reduce night-time body temperature and pyrogen-related factors. [ABSTRACT FROM AUTHOR]

Abstract: Glucokinase (GK), an enzyme that phosphorylates glucose to form glucose-6-phosphate, has a role in regulating insulin secretion and proliferation in beta cells. GK activators (GKAs) have been developed as new therapies for type 2 diabetes. In this study, we evaluated the proliferation and anti-apoptotic actions of YH-GKA, a novel and potent GKA, in INS-1 pancreatic β-cells. YH-GKA treatment increased cell numbers at 3mM glucose via upregulation of insulin receptor substrate-2 and subsequent activation of AKT/protein kinase B phosphorylation. YH-GKA also increased beta-catenin and cyclin D2 mRNA expression and inactivated GSK3β by increasing phosphorylation. These proliferative effects of YH-GKA were attenuated by IRS-2 downregulation. Moreover, YH-GKA reduced annexin-V-stained cells and expression levels of cleaved poly (ADP-ribose) polymerase and caspase-3 induced by glucotoxicity. YH-GKA inhibited apoptotic signaling via induction of ATP content, mitochondrial membrane potential, and citrate synthase activity and was correlated with changes of the mitochondrial function-related genes. YH-GKA also increased interaction between GK and voltage-dependent anion-selective channel protein. Our results suggest that the novel GKA, YH-GKA, promotes beta cell growth and prevents glucotoxic beta cell apoptosis. Therefore, YH-GKA may provide a therapy that compensates for beta cell loss in patients with type 2 diabetes. [Copyright &y& Elsevier]

Potential therapeutic use of human adipose tissue-derived stem cells (hADSCs) requires the production of large cell numbers by in vitro expansion. However, long-term in vitro culture is associated with reduced stem cell characteristics and differentiation capability. We investigated the proliferation rate and expression of p16INK4a mRNA, surface stem cell markers, and stem cell transcription factors. The proliferation rate decreased significantly as passages increased, and the expression of p16INK4a mRNA significantly increased. FACS analysis of CD73, CD90, and CD105 expression showed no significant difference among examined passages; however, the mRNA expression levels of pluripotent markers, Oct4 and Nanog, were significantly decreased at higher passages. At passages 12 and 20, there was decreased differentiation capability into insulin-producing cells, evidenced by significantly decreased expression of insulin and related β cell markers. Adipogenic and osteogenic differentiation was also decreased at higher passages. We then analyzed the transcriptional expression profiles of 48 nuclear receptors at four different passages. We found that the expression of peroxisome proliferator-activated receptor γ (PPARγ) and thyroid hormone receptor TRβ was significantly decreased at higher passages. Treatment with PPARγ activators or overexpression of PPARγ in hADSCs at passage 20 could recover Oct4 expression levels and increase Oct4 promoter activity. PPARγ inactivation by GW9662 inhibited the troglitazone-induced Oct4 mRNA expression. Furthermore, PPARγ overexpression in hADSC at passage 20 improved the differentiation potential to insulin-producing cells. In conclusion, we demonstrated that hADSCs undergo characteristic changes and reduction of differentiation capability during expanded culture in vitro, and revealed the role of PPARγ as one potential factor in the regulation of Oct4 expression during in vitro aging of hADSCs. [ABSTRACT FROM AUTHOR]

Abstract: Aging-dependent physiological conditions are attributed to parenchymal structural changes to cellular functions in aged organisms. Compared to the young animals, the primary hepatocytes from old rats showed a higher glucose output and a higher expression of the key gluconeogenesis-regulating enzyme, phosphoenol pyruvate carboxykinase (PEPCK). The primary hepatocytes from old rats showed a higher glucose output and a higher expression of the key gluconeogenesis-regulating enzyme, phosphoenol pyruvate carboxykinase (PEPCK), compared with those from the young animals. The in situ hybridization study showed increased PEPCK mRNA expression in the aged liver tissues. The livers from old rats showed loosened hexagonal hepatic lobular structures, increased collagen accumulation, and high expression of the hypoxia marker hypoxia-inducible factor 1α (HIF1α). Hypoxia increased the PEPCK mRNA and protein expression levels in accordance with the HIF1α expression. PEPCK promoter luciferase reporter assay showed that hypoxia increased PEPCK through transcriptional activation. Furthermore, the hepatocyte nuclear factor α (HNF4α) protein, but not the HNF4α mRNA level, increased in parallel with the PEPCK mRNA expression under hypoxic conditions. Glucose production increased under hypoxic conditions, but this increment diminished by HNF4α siRNA in young hepatocytes. Moreover, increased glucose production from old rat hepatocytes was reversed by the down-regulation of HNF4α through a specific siRNA. This study suggests that the mild hypoxic conditions in response to aging-dependent hepatic structural changes may contribute to the induction of the gluconeogenic enzyme PEPCK through HNF4α protein stabilization. [Copyright &y& Elsevier]

Recent studies comparing the insulin-producing cell (IPC) differentiation capacity of mesenchymal stem cells (MSCs) derived from four different sources (bone marrow, Wharton's jelly, adipose tissue, and the periosteum) demonstrated that IPC differentiation of periosteum-derived progenitor cells (PDPCs) progressed faster than any other MSCs within 7 days, indicating that PDPCsare most suited to IPC differentiation. Here, two different cell culture methods, adhesion and cluster culture, were assessed for their ability to support in vitro IPC differentiation. The induction of IPC differentiation was confirmed by RTqPCR analysis of insulin gene expression levels and immunofluorescence analysis of insulin protein. An enzyme-linked immunosorbent assay was used to quantify secreted insulin. PDPC-derived IPCs from cluster cultures demonstrated a significantly increased expression of insulin and an enhanced secretion of insulin of insulin protein in response to glucose compared to IPCs derived from adhesion cultures. Thus, pancreatic islet-like cluster cultures appear to provide the optimal conditions such as cluster culture for IPC differentiation of PDPCs. [ABSTRACT FROM AUTHOR]

Summary This study investigated the effect of local glucagon-like peptide-1 (GLP-1) production within mouse islets on cytoprotection in vitro and in vivo by gene transfer of GLP-1. Transduction of recombinant adenovirus vector expressing GLP-1 (rAd-GLP-1) induced a significant increase in bioactive GLP-1 in the mouse islet culture, whereas transduction with adenovirus vector expressing β-galactosidase (rAd-LacZ), as a control, had no effect on GLP-1 secretion. Islets transduced with rAd-GLP-1 were protected from H2O2-induced cell damage in vitro. In addition, glucose-stimulated insulin secretion was significantly increased in rAd-GLP-1-transduced islets. When transplanted under the kidney capsule of diabetic syngeneic mice, islet grafts retrieved 4 or 7 days after transplantation revealed that the rAd-GLP-1-transduced group had significantly more Ki67-positive cells as compared with the rAd-LacZ-transduced group. Regarding blood glucose control, diabetic mice transplanted with a marginal mass of rAd-GLP-1-transduced islets became normoglycemic more rapidly and 78% of the recipients were normoglycemic at 35 days post-transplant, whereas only 48% of the mice transplanted with rAd-LacZ-transduced islets were normoglycemic ( P < 0.05). In conclusion, delivery of the GLP-1 gene to islets enhanced islet cell survival during the early post-transplant period, and preserved islet mass and functions over time in the transplants. [ABSTRACT FROM AUTHOR]

Background: Betacellulin (BTC), a member of the epidermal growth factor family, is known to play an important role in regulating growth and differentiation of pancreatic beta cells. Growth-promoting actions of BTC are mediated by epidermal growth factor receptors (ErbBs), namely ErbB-1, ErbB-2, ErbB-3 and ErbB-4; however, the exact mechanism for beta cell proliferation has not been elucidated. Therefore, we investigated which ErbBs are involved and some molecular mechanisms by which BTC regulates beta cell proliferation. Methodology/Principal Findings: The expression of ErbB-1, ErbB-2, ErbB-3, and ErbB-4 mRNA was detected by RT-PCR in both a beta cell line (MIN-6 cells) and C57BL/6 mouse islets. Immunoprecipitation and western blotting analysis showed that BTC treatment of MIN-6 cells induced phosphorylation of only ErbB-1 and ErbB-2 among the four EGF receptors. BTC treatment resulted in DNA synthetic activity, cell cycle progression, and bromodeoxyuridine (BrdU)-positive staining. The proliferative effect was blocked by treatment with AG1478 or AG825, specific tyrosine kinase inhibitors of ErbB-1 and ErbB-2, respectively. BTC treatment increased mRNA and protein levels of insulin receptor substrate-2 (IRS-2), and this was blocked by the ErbB-1 and ErbB-2 inhibitors. Inhibition of IRS-2 by siRNA blocked cell cycle progression induced by BTC treatment. Streptozotocin-induced diabetic mice injected with a recombinant adenovirus expressing BTC and treated with AG1478 or AG825 showed reduced islet size, reduced numbers of BrdU-positive cells in the islets, and did not attain BTC-mediated remission of diabetes. Conclusions/Significance: These results suggest that BTC exerts proliferative activity on beta cells through the activation of ErbB-1 and ErbB-2 receptors, which may increase IRS-2 expression, contributing to the regeneration of beta cells. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study is to investigate the effect of mitochondrial metabolism on high glucose/palmitate (HG/PA)-induced INS-1 beta cell death. Long-term treatment of INS-1 cells with HG/PA impaired energy-producing metabolism accompanying with depletion of TCA cycle intermediates. Whereas an inhibitor of carnitine palmitoyl transferase 1 augmented HG/PA-induced INS-1 cell death, stimulators of fatty acid oxidation protected the cells against the HG/PA-induced death. Furthermore, whereas mitochondrial pyruvate carboxylase inhibitor phenylacetic acid augmented HG/PA-induced INS-1 cell death, supplementation of TCA cycle metabolites including leucine/glutamine, methyl succinate/α-ketoisocaproic acid, dimethyl malate, and valeric acid or treatment with a glutamate dehydrogenase activator, aminobicyclo-heptane-2-carboxylic acid (BCH), significantly protected the cells against the HG/PA-induced death. In particular, the mitochondrial tricarboxylate carrier inhibitor, benzene tricarboxylate (BTA), also showed a strong protective effect on the HG/PA-induced INS-1 cell death. Knockdown of glutamate dehydrogenase or tricarboxylate carrier augmented or reduced the HG/PA-induced INS-1 cell death, respectively. Both BCH and BTA restored HG/PA-induced reduction of energy metabolism as well as depletion of TCA intermediates. These data suggest that depletion of the TCA cycle intermediate pool and impaired energy-producing metabolism may play a role in HG/PA-induced cytotoxicity to beta cells and thus, HG/PA-induced beta cell glucolipotoxicity can be protected by nutritional or pharmacological maneuver enhancing anaplerosis or reducing cataplerosis. [ABSTRACT FROM AUTHOR]

An abstract of the article "Glucose-Dependent Insulin Production by Liver-Specific, Glucose-Regulatable Synthetic Promoters Results in the Cure of Diabetes," by Jaeseok Han, Brienne McLane, Hee-Sook Jun and Ji-Won Yoon is presented.

Psoriasis is a chronic inflammatory skin disease. Recently, lysophosphatidic acid (LPA)/LPAR5 signaling has been reported to be involved in both NLRP3 inflammasome activation in macrophages and keratinocyte activation to produce inflammatory cytokines, contributing to psoriasis pathogenesis. However, the effect and molecular mechanisms of LPA/LPAR signaling in keratinocyte proliferation in psoriasis remain unclear. In this study, we investigated the effects of LPAR1/3 inhibition on imiquimod (IMQ)-induced psoriasis-like mice. Treatment with the LPAR1/3 antagonist, ki16425, alleviated skin symptoms in IMQ-induced psoriasis-like mouse models and decreased keratinocyte proliferation in the lesion. It also decreased LPA-induced cell proliferation and cell cycle progression via increased cyclin A2, cyclin D1, cyclin-dependent kinase (CDK)2, and CDK4 expression and decreased p27Kip1 expression in HaCaT cells. LPAR1 knockdown in HaCaT cells reduced LPA-induced proliferation, suppressed cyclin A2 and CDK2 expression, and restored p27Kip1 expression. LPA increased Rho-associated protein kinase 2 (ROCK2) expression and PI3K/AKT activation; moreover, the pharmacological inhibition of ROCK2 and PI3K/AKT signaling suppressed LPA-induced cell cycle progression. In conclusion, we demonstrated that LPAR1/3 antagonist alleviates IMQ-induced psoriasis-like symptoms in mice, and in particular, LPAR1 signaling is involved in cell cycle progression via ROCK2/PI3K/AKT pathways in keratinocytes. [ABSTRACT FROM AUTHOR]

Pluripotent adult stem cells have potential applications in cell therapy and tissue engineering. Urine-derived stem cells (UDSCs) differentiate into various cell types. Here, we attempted to differentiate human UDSCs (hUDSCs) into smooth muscle cells (SMCs) using transforming growth factor-beta 1 (TGF-β1) and/or PD98059, an extracellular signal-regulated kinase (ERK) inhibitor. Both quantitative polymerase chain reaction (qPCR) and Western blot analysis showed that the expression of messenger ribonucleic acid (mRNA) and proteins for alpha-smooth muscle actin (α-SMA), calponin (CNN1), and smooth muscle myosin heavy chain (SM-MHC), which are specific markers for SMCs, increased on day 9 after differentiation and again on day 14. The differentiated cells from human UDSCs (hUDSCs) with a combination of TGF-β1 and PD98059 showed the highest expression of SMC marker proteins. Immunocytochemical staining performed to assess the molecular expression revealed CNN and α-SMA colocalizing in the cytoplasm. The cells that differentiated from hUDSCs with a combination of TGF-β1 and PD98059 showed the strongest expression for CNN1, α-SMA, and SM-MHC. Functional testing of the differentiated cells revealed a stronger contractile capacity for the cells differentiated with a combination of PD98059 and TGF-β1 than those differentiated with a single factor. These results suggest the combination of PD98059 and TGF-β1 to be a more effective differentiation method and that differentiated SMCs could be used for restoring the functions of the sphincter muscle or bladder. [ABSTRACT FROM AUTHOR]