Jie Du

Glutamate in peripheral organs: Biology and pharmacology.

Glutamate is a versatile molecule existing in both the central nervous system and peripheral organs. Previous studies have mainly focussed on the biological effect of glutamate in the brain. Recently, abundant evidence has demonstrated that glutamate also participates in the regulation of physiopathological functions in peripheral tissues, including the lung, kidney, liver, heart, stomach and immune system, where the glutamate/glutamate receptor/glutamate transporter system plays an important role in the pathogenesis of certain diseases, such as myocardial ischaemia/reperfusion injury and acute gastric mucosa injury. All these findings provide new insight into the biology and pharmacology of glutamate and suggest a potential therapeutic role of glutamate in non-neurological diseases.

Role of eukaryotic translation initiation factor 3a in bleomycin-induced pulmonary fibrosis.

Eukaryotic translation initiation factor 3a (eIF3a) is a multifunctional protein and plays an important role in regulation of cellular function including proliferation and differentiation. In the present study, we tested the function of eIF3a in pulmonary fibrosis. Pulmonary fibrosis was induced by intratracheal instillation of bleomycin (5mg/kg) in rats. Primary pulmonary fibroblasts were cultured for proliferation investigation by BrdU incorporation method and flow cytometry. The expression/level of eIF3a, TGF-β1, ERK1/2 and α-SMA were analyzed by ELISA, real-time PCR or western blot. Results showed that the expression of eIF3a was obviously increased in lungs of pulmonary fibrosis rats accompanied by up-regulation of α-SMA and collagens. In cultured pulmonary fibroblasts, application of exogenous TGF-β1 induced cell proliferation and differentiation concomitantly with up-regulation of eIF3a expression and ERK1/2 phosphorylation. The effects of TGF-β1-induced proliferation of fibroblasts and up-regulation of α-SMA were abolished by eIF3a siRNA. TGF-β1-induced eIF3a expression was reversed in the presence of PD98059, an inhibitor of ERK1/2. These findings suggest that eIF3a plays an important role in bleomycin-induced pulmonary fibrosis by regulating pulmonary fibroblasts׳ function, and up-regulation of eIF3a induced by TGF-β1 is mediated via the ERK1/2 pathway.

Role of eukaryotic translation initiation factors 3a in hypoxia-induced right ventricular remodeling of rats.

AIM Eukaryotic translation initiation factors 3a (eIF3a) is involved in regulating cell cycle, cell division, growth and differentiation. Previous studies suggest a role of eIF3a on fibrosis disease and cellular proliferation and differentiation of fibroblasts. The present study aims to investigate the role of eIF3a on hypoxia-induced right ventricular (RV) remodeling and underlying mechanism. MAIN METHODS RV remodeling was induced by hypoxia (10% O2, 3 weeks) in rats. Primary cardiac fibroblasts were cultured in vitro and their proliferation was investigated by MTS and EdU incorporation method. eIF3a knockdown was conducted by eIF3a siRNA. The expression/level of TGF-β1, eIF3a, p27 and α-SMA, collagen-I, collagen-III, ANP and BNP were analyzed by ELISA, real-time PCR or Western blot. KEY FINDINGS The expression of eIF3a was obviously increased in right ventricle of RV remodeling rats accompanied by up-regulation of α-SMA and collagens. In cultured cardiac fibroblasts, application of exogenous TGF-β1-induced cellular proliferation and differentiation concomitantly with up-regulation of eIF3a expression and down-regulation of p27 expression. The effects of TGF-β1-induced proliferation and up-regulation of α-SMA and collagen in cardiac fibroblasts were abolished by eIF3a siRNA. eIF3a siRNA reversed TGF-β1 induced down-regulation of p27 expression. SIGNIFICANCE The eIF3a plays a crucial role in hypoxia-induced RV remodeling by regulating TGF-β1-induced proliferation and differentiation of cardiac fibroblasts, which is mediated via eIF3a/p27 pathway.

Involvement of glutamate-cystine/glutamate transporter system in aspirin-induced acute gastric mucosa injury.

Large-dose or long-term use of aspirin tends to cause gastric mucosa injury, which is recognized as the major side effect of aspirin. It has been demonstrated that glutamate exerts a protective effect on stomach, and the level of glutamate is critically controlled by cystine/glutamate transporter (Xc(-)). In the present study, we investigated the role of glutamate-cystine/glutamate transporter system in aspirin-induced acute gastric mucosa injury in vitro and in vivo. Results showed that in human gastric epithelial cells, aspirin incubation increased the activity of LDH and the number of apoptotic cells, meanwhile down-regulated the mRNA expression of Xc(-) accompanied with decreased glutamate release. Similar results were seen in a rat model. In addition, exogenous l-glutamate attenuated the gastric mucosa injury and cell damage induced by aspirin both in vitro and in vivo. Taken together, our results demonstrated that acute gastric mucosa injury induced by aspirin is related to reduction of glutamate-cystine/glutamate transporter system activity.

Role of caspase-3/E-cadherin in helicobacter pylori-induced apoptosis of gastric epithelial cells

This study was designed to investigate the role of caspase-3/E-cadherin in Helicobacter pylori (H. pylori) -induced gastric epithelial apoptosis in cells, animal models and clinical gastritis patients. In cultured gastric mucosal epithelial cells, gastric glandular epithelial cells and C57BL/6 mice, H. pylori infection significantly induced apoptosis of gastric epithelial cells, down-regulated full-length E-cadherin and Bcl-2 expression, and up-regulated cleaved-caspase-3, E-cadherin/carboxy-terminal fragment 3 and Bax expression. Z-DEVD-FMK, an inhibitor of caspase-3, attenuated the effect of H. pylori. E-cadherin overexpression significantly inhibited the apoptosis of GES-1 and SGC-7901 cells induced by the H. pylori. The results from clinical studies also showed down-regulation of E-cadherin, up-regulation of cleaved-caspase-3 expression and increased apoptosis in gastric tissues from gastritis patients with H. pylori infection. These results suggest that the caspase-3/E-cadherin pathway is involved in the apoptosis of gastric epithelial cells induced by H. pylori.This study was designed to investigate the role of caspase-3/E-cadherin in Helicobacter pylori (H. pylori) -induced gastric epithelial apoptosis in cells, animal models and clinical gastritis patients. In cultured gastric mucosal epithelial cells, gastric glandular epithelial cells and C57BL/6 mice, H. pylori infection significantly induced apoptosis of gastric epithelial cells, down-regulated full-length E-cadherin and Bcl-2 expression, and up-regulated cleaved-caspase-3, E-cadherin/carboxy-terminal fragment 3 and Bax expression. Z-DEVD-FMK, an inhibitor of caspase-3, attenuated the effect of H. pylori. E-cadherin overexpression significantly inhibited the apoptosis of GES-1 and SGC-7901 cells induced by the H. pylori. The results from clinical studies also showed down-regulation of E-cadherin, up-regulation of cleaved-caspase-3 expression and increased apoptosis in gastric tissues from gastritis patients with H. pylori infection. These results suggest that the caspase-3/E-cadherin pathway is involved in the apoptosis of gastric epithelial cells induced by H. pylori.

Fluorofenidone attenuates vascular remodeling in hypoxia-induced pulmonary hypertension of rats.

Fluorofenidone (AKF-PD) is a novel pyridone derivate that targets transforming growth factor-β1 (TGF-β1) signaling. Previous studies have proven that AKF-PD functions as an antifibrotic agent in pulmonary fibrosis and renal fibrosis models. Activated TGF-β1 signaling is thought to be a major feature of pulmonary hypertension (PH). TGF-β1 exerts powerful pro-proliferation effects on pulmonary arterial smooth muscle cells (PASMCs), and hence, prompts vascular remodeling. This study is designed to investigate the effect of AKF-PD on vascular remodeling in a rat model of hypoxia-induced PH. PH was induced in rats by 4 weeks of hypoxia. The expression of TGF-β1, collagen I, and collagen III was analyzed by ELISA, immunohistochemistry, real-time PCR, or Western blot. Proliferation of cultured PASMCs was determined by the BrdU incorporation method and flow cytometry. The results showed that AKF-PD treatment (0.5 or 1.0 g·(kg body mass)·d(-1)) for 4 weeks attenuated pulmonary vascular remodeling and improved homodynamic parameters. TGF-β1 level was significantly down-regulated by AKF-PD both in vivo and in vitro. Furthermore, hypoxia- and TGF-β1-induced PASMC proliferation and collagen expression were both significantly suppressed by AKF-PD. These results suggest that AKF-PD ameliorates the progression of PH induced by hypoxia in rats through its regulation of TGF-β1 expression, PASMC proliferation, and the extracellular matrix.

Involvement of microRNAs-MMPs-E-cadherin in the migration and invasion of gastric cancer cells infected with Helicobacter pylori

ABSTRACT It has been found that Helicobacter pylori (H. pylori)is not only the main cause of gastric cancer, but also closely related to its metastasis. E‐cadherin cleavage induced by matrix metalloproteinases (MMPs) plays an important role in the tumor metastasis. In the present study, we investigated the role of microRNAs‐MMPs‐E‐cadherin in migration and invasion of gastric cancer cells treated with H. pylori. The results showed that H. pylori induced migration and invasion of SGC‐7901 cells with a down‐regulation of E‐cadherin expression, which were abolished by MMPs knock down, E‐cadherin overexpression, mimics of miR128 and miR148a. MiR128/miR148a inhibitors restored MMP‐3/MMP‐7 expression, down‐regulated E‐cadherin level, and accelerated cellular migration and invasion. This study suggests that H. pylori induces migration and invasion of gastric cancer cells through reduction of E‐cadherin function by activation of MMP‐3, −7. The present results also suggest that the activated MMPs/E‐cadherin pathway is related with down‐regulation of miR128/miR148a in the human gastric cancer cells infected with H. pylori. HIGHLIGHTSInvolvement of microRNAs‐MMPs‐E‐cadherin in migration and invasion of gastric cancer cells induced by H. pylori.Reduction of E‐cadherin function by activation of MMP‐3, ‐7 in H. pylori infection.Modulation of MMPs/E‐cadherin pathway by miR128/miR148a in gastric cancer cells infected with H. pylori.

Calcitonin gene-related peptide inhibits the cardiac fibroblasts senescence in cardiac fibrosis via up-regulating klotho expression

ABSTRACT It has been documented cardiac fibroblasts as the predominant cell population undergoing senescence in heart. Calcitonin gene‐related peptide (CGRP) exhibits a wide range of cardiovascular protective effects. Whether CGRP protects against cardiac fibroblasts senescence in cardiac fibrosis remains unknown. Here, we detected the down‐regulation of CGRP concomitant with senescence in fibrotic myocardium, both hypertension‐ induced left ventricular fibrosis in SHR rats and hypoxia‐induced right ventricular fibrosis in pulmonary artery hypertension rats. Exogenous CGRP inhibited the cardiac fibroblasts senescence and senescence‐associated secretory phenotype (SASP) induced by TGF‐&bgr;1, which was abolished by CGRP8–37, a selective CGRP receptor antagonist. Moreover, the expression of klotho, an anti‐senescence protein, was down‐regulated in fibrotic myocardium, and CGRP up‐regulated the klotho expression in TGF‐&bgr;1‐treated cardiac fibroblasts. Klotho knockdown by siRNA reversed the inhibition of CGRP on senescence and SASP induced by TGF‐&bgr;1 in cardiac fibroblasts. These results suggested that CGRP inhibited the cardiac fibroblasts senescence and SASP in cardiac fibrosis via up‐regulating klotho expression. Graphical abstract Figure. No Caption available.