Forkhead transcription factor FoxO1 inhibits insulin- and transforming growth factor-beta-stimulated plasminogen activator inhibitor-1 expression

Intervention Study of Dictyophora Polysaccharides on Arsenic-Induced Liver Fibrosis in SD Rats

Long-term arsenic (As) exposure can cause liver injury, hepatic cirrhosis, and cancer. Meanwhile, Dictyophora polysaccharides (DIP) have excellent antioxidation, anti-inflammation, and immune protection effects. There are currently few reports on the protection effects of DIP on As-induced hepatotoxicity and its pharmacological value. Therefore, this study was aimed at elucidating the protection of DIP on As-induced hepatotoxicity and exploring its preventive role in antifibrosis. In our study, the SD rat As poisoning model was established by the feeding method to explore the influence of As exposure on liver fibrosis. Then, DIP treatment was applied to the rats with As-induced liver fibrosis, and the changes of serum biochemical indexes and liver tissue pathology were observed. And the expression of fibrosis-related proteins TGF-β1, CTGF, and α-SMA levels was then determined to explore the DIP intervention function. The results demonstrated that through reduced pathological changes of hepatic and increased serum AST, ALT, TP, ALB, and A/G levels, DIP ameliorated liver fibrosis induced by As as reflected. And the administration of DIP decreased the concentration of HA, LN, PCIII, CIV, TBIL, and DBIL. In addition, the synthesis of TGF-β1 inhibited by DIP might regulate the expression of CTGF and decrease the proliferation of fibrinogen and fibroblasts, which reduced the synthesis of fibroblasts to transform into myofibroblasts. And a decrease of myofibroblasts downregulated the expression of α-SMA, which affected the synthesis and precipitation of ECM and alleviated the liver fibrosis caused by exposure to As. In conclusion, based on the pathological changes of liver tissue, serum biochemical indexes, and related protein expression, DIP can improve the As-induced liver fibrosis in rats and has strong medicinal value.

Liraglutide ameliorates early renal injury by the activation of renal FoxO1 in a type 2 diabetic kidney disease rat model

AIMS

The aim of this study was to investigate the effects of liraglutide on renal injury and the renal expression of FoxO1 in type 2 diabetic rats.

METHODS

Type 2 diabetic rats model was induced by a high-sugar and high-fat diet and intraperitoneal injection of low-dose Streptozotocin (STZ) (30 mg/kg). Five weeks after STZ injection, diabetic rats were randomly treated with or without subcutaneous injection of liraglutide (0.2 mg/kg/12 h) for eight weeks. Diabetes-related physical and biochemical indicators, renal histopathological and ultrastructural changes, the expression of renal transforming growth factor beta-1 (TGF-β1), fibronectin (FN), type IV collagen (Col IV), protein kinase B (Akt), forkhead box protein O1 (FoxO1) and manganese superoxide dismutase (MnSOD) were measured.

RESULTS

Rats in DN group showed a significant increase in fasting blood glucose, HbA1c, kidney to body weight index, serum creatinine (Scr), blood urea nitrogen (BUN), urinary albumin excretion, mesangial matrix index, glomerular basement membrane (GBM) thickening, podocyte foot process fusion, the mRNA and protein levels of renal TGF-β1, FN and Col IV and a dramatic decrease in the mRNA and protein levels of renal MnSOD, all of which were significantly ameliorated by liraglutide. In addition, liraglutide also increased the expression of FoxO1 mRNA and reduced renal phosphorylation levels of Akt and FoxO1 protein.

CONCLUSIONS

These results suggest that liraglutide may exert a renoprotective effect by a FoxO1-mediated upregulation of renal MnSOD expression in the early DKD.

Lentiviral Vector-Mediated FoxO1 Overexpression Inhibits Extracellular Matrix Protein Secretion Under High Glucose Conditions in Mesangial Cells

Diabetic nephropathy is characterized by inordinate secretion of extracellular matrix (ECM) proteins from mesangial cells (MCs), which is tightly associated with excessive activation of TGF-β signaling. The forkhead transcription factor O1 (FoxO1) protects mesangial cells from hyperglycemia-induced oxidative stress, which may be involved in ameliorating the redundant secretion of ECM proteins under high glucose conditions. Here, we reported that high glucose elevated the level of p-Akt to attenuate endogenous FoxO1 bioactivities in MCs, accompanied with decreases in the mRNA expressions of catalase (CAT) and superoxide dismutase 2 (SOD2). Meanwhile, the expressions of major ECM proteins-FN and Col I-increased under high glucose conditions, in consistent with the activation of TGF-β/Smad signaling. By contrast, overexpression of nucleus-localized FoxO1 (insensitive to Akt phosphorylation) directly up-regulated the expressions of anti-oxidative enzymes, accompanied with inactivation of TGF-β/Smad3 pathway, as well as decreases of extracellular matrix proteins. Moreover, similar to those MCs overexpressed of nucleus-localized FoxO1 in high glucose conditions, MCs with down-regulation of FoxO1 by small interference-RNA under normal glucose conditions showed increased FN level and activated TGF-β/Smad3 pathway. Our findings link the anti-oxidative activity of FoxO1 and the TGF-β-induced secretion of ECM proteins, indicating the novel role of FoxO1 in protecting MCs under high glucose conditions.

Endothelial Plasticity: Shifting Phenotypes through Force Feedback

The endothelial lining of the vasculature is exposed to a large variety of biochemical and hemodynamic stimuli with different gradients throughout the vascular network. Adequate adaptation requires endothelial cells to be highly plastic, which is reflected by the remarkable heterogeneity of endothelial cells in tissues and organs. Hemodynamic forces such as fluid shear stress and cyclic strain are strong modulators of the endothelial phenotype and function. Although endothelial plasticity is essential during development and adult physiology, proatherogenic stimuli can induce adverse plasticity which contributes to disease. Endothelial-to-mesenchymal transition (EndMT), the hallmark of endothelial plasticity, was long thought to be restricted to embryonic development but has emerged as a pathologic process in a plethora of diseases. In this perspective we argue how shear stress and cyclic strain can modulate EndMT and discuss how this is reflected in atherosclerosis and pulmonary arterial hypertension.

Tongxinluo Protects against Hypertensive Kidney Injury in Spontaneously-Hypertensive Rats by Inhibiting Oxidative Stress and Activating Forkhead Box O1 Signaling

Hypertension is an independent risk factor for the progression of chronic renal failure, and oxidative stress plays a critical role in hypertensive renal damage. Forkbox O1(FoxO1) signaling protects cells against oxidative stress and may be a useful target for treating oxidative stress-induced hypertension. Tongxinluo is a traditional Chinese medicine with cardioprotective and renoprotective functions. Therefore, this study aimed to determine the effects of Tongxinluo in hypertensive renal damage in spontaneously hypertensive rats(SHRs)and elucidate the possible involvement of oxidative stress and FoxO1 signaling in its molecular mechanisms. SHRs treated with Tongxinluo for 12 weeks showed a reduction in systolic blood pressure. In addition to increasing creatinine clearance, Tongxinluo decreased urinary albumin excretion, oxidative stress injury markers including malondialdehyde and protein carbonyls, and expression of nicotinamide adenine dinucleotide phosphate oxidase subunits and its activity in SHR kidneys. While decreasing phosphorylation of FoxO1, Tongxinluo also inhibited the phosphorylation of extracellular signal-regulated kinase1/2 and p38 and enhanced manganese superoxide dismutase and catalase activities in SHR kidneys. Furthermore, histology revealed attenuation of glomerulosclerosis and renal podocyte injury, while Tongxinluo decreased the expression of α-smooth muscle actin, extracellular matrixprotein, transforming growth factor β1 and small mothers against decapentaplegic homolog 3,and improved tubulointerstitial fibrosis in SHR kidneys. Finally, Tongxinluo inhibited inflammatory cell infiltration as well as expression of tumor necrosis factor-α and interleukin-6. In conclusion, Tongxinluo protected SHRs against hypertension-induced renal injury by exerting antioxidant, antifibrotic, and anti-inflammatory activities. Moreover, the underlying mechanisms of these effects may involve inhibition of oxidative stress and functional activation of FoxO1 signaling.

Overexpression of the FoxO1 Ameliorates Mesangial Cell Dysfunction in Male Diabetic Rats

The dysfunction of mesangial cells (MCs) in high-glucose (HG) conditions plays pivotal role in inducing glomerular sclerosis by causing the imbalance between generation and degradation of extracellular matrix (ECM) proteins, which ultimately leads to diabetic nephropathy. This study was designed to determine the function of forkhead box protein O1 (FoxO1), an important transcription factors in regulating cell metabolism and oxidative stress, in MCs in HG conditions. Up-regulation of fibronectin, collagen type IV, and plasminogen activator inhibitor (PAI-1) was observed under HG conditions in vivo and in vitro, accompanied with elevation of protein kinase B (Akt) phosphorylation and reduction of FoxO1 bioactivity. After overexpression of constitutively active (CA) FoxO1 in vivo and in vitro by using lentivirus vector, in vivo and in vitro, FoxO1 expression and activity was increased, in accordance with up-regulation of antioxidative genes (catalase and superoxide dismutase, leading to alleviated oxidative stress as well as attenuated Akt activity, whereas overexpression of wild type-FoxO1 only expressed partial effect. Moreover, CA-FoxO1 decreased the expression of fibronectin, collagen type IV, and PAI-1, causing amelioration of renal pathological changes and decrease of ECM protein deposition in glomerulus. Overexpression of CA-FoxO1 in renal cortex also decreased activin type-I receptor-like kinase-5 levels and increased signaling mothers against decapentaplegic (Smad) 7 levels, and simultaneously inhibited Smad3 phosphorylation. Results from in vitro study indicated that increased combination of FoxO1 and Smad3 may interfere with the function of Smad3, including Smad3 phosphorylation and translocation, interaction with cAMP response element binding protein (CREB)-binding protein, and binding with PAI-1 promoter. Together, our findings shed light on the novel function of FoxO1 in inhibiting ECM deposition, which is beneficial to ameliorate MC dysfunction.

The PAX3-FOXO1 fusion protein present in rhabdomyosarcoma interferes with normal FOXO activity and the TGF-β pathway

PAX3-FOXO1 (PAX3-FKHR) is the fusion protein produced by the genomic translocation that characterizes the alveolar subtype of Rhabdomyosarcoma, a pediatric sarcoma with myogenic phenotype. PAX3-FOXO1 is an aberrant but functional transcription factor. It retains PAX3-DNA-binding activity and functionally overlaps PAX3 function while also disturbing it, in particular its role in myogenic differentiation. We herein show that PAX3-FOXO1 interferes with normal FOXO function. PAX3-FOXO1 affects FOXO-family member trans-activation capability and the FOXO-dependent TGF-β response. PAX3-FOXO1 may contribute to tumor formation by inhibiting the tumor suppressor activities which are characteristic of both FOXO family members and TGF-β pathways. The recognition of this mechanism raises new questions about how FOXO family members function.

Nanoscale hepatoprotective herbal decoction attenuates hepatic stellate cell activity and chloroform-induced liver damage in mice

BACKGROUND

San-Huang-Xie-Xin-Tang (SHXXT) decoction, a traditional Chinese medicine containing Rhei rhizome, Coptidis rhizome, and Scutellariae radix, is widely used in hepatoprotective therapy. However, preparation of the decoction requires addition of boiling water that causes loss of numerous effective components.

METHODS

To improve the bioavailability of the decoction, nanoscale SHXXT was developed. Chloroform-induced liver injury and hepatic stellate cell activity in mice were used to demonstrate the hepatoprotective characteristics of nanoscale SHXXT decoction.

RESULTS

Liver/body weight ratio and serum aspartate and alanine aminotranferase levels were recovered by the nanoscale SHXXT. TIMP-1 gene expression was inhibited and MMP-2 gene expression was accelerated in activated hepatic stellate cells.

CONCLUSION

Nanoscale SHXXT decoction prepared in room temperature water could have preserved hepatoprotective ability. The results of this study indicate that nanoscale SHXXT could be extracted easily. The simple preparation of this herbal decoction is more convenient and energy-efficient.

Advances in research on the role of cytokines in chronic liver diseases

Cytokines play an important role in the development of liver inflammatory injury. Various pro-inflammatory and anti-inflammatory cytokines constitute a cytokine network that mediates the development of various liver diseases. In recent years, numerous studies have been carried out on chronic liver diseases such as viral hepatitis, fatty liver, alcoholic liver disease and hepatic cirrhosis. Here, we will review the recent advances in research on the role of cytokines in chronic liver diseases and discuss future prospects in this field.