SOX9 promotes hypoxic pulmonary hypertension through stabilization of DPP4 in pulmonary artery smooth muscle cells.

Pulmonary hypertension (PH) is a progressive cardiopulmonary disorder characterized by pulmonary vascular remodeling (PVR), primarily due to the excessive proliferation of pulmonary artery smooth muscle cells (PASMCs). This study aimed to investigate the role and molecular mechanism of SOX9 in hypoxic PH in rats. The findings revealed that SOX9 was upregulated in the pulmonary arteries and PASMCs of hypoxia-exposed rats. SOX9 knockdown inhibited hypoxia-induced proliferation and migration of PASMCs, reduced PVR, and subsequently alleviated hypoxia-induced PH in rats, suggesting that SOX9 plays a critical role in PH. Further investigation demonstrated that SOX9 interacted with DPP4, preventing its ubiquitin degradation in hypoxia-exposed PASMCs. DPP4 knockdown inhibited hypoxia-induced PASMC proliferation and migration, and administration of the DPP4 inhibitor sitagliptin (5 mg/kg) significantly reduced PVR and alleviated hypoxia-induced PH in rats, indicating that SOX9 contributes to PH by stabilizing DPP4. The results also showed that hypoxia induced YAP1 expression and dephosphorylation, leading to YAP1 nuclear localization. YAP1 knockdown promoted the degradation of HIF-1α in hypoxia-exposed PASMCs and inhibited hypoxia-induced proliferation and migration of PASMCs. Additionally, HIF-1α, as a transcription factor, promoted SOX9 expression by binding to the SOX9 promoter in hypoxia-exposed PASMCs. In conclusion, hypoxia promotes the proliferation and migration of PASMCs through the regulation of the YAP1/HIF-1α/SOX9/DPP4 signaling pathway, leading to PH in rats. These findings suggest that SOX9 may serve as a potential prognostic marker and therapeutic target for PH.

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Multisystem inflammatory syndrome in children (MIS-C) is a type of hyperinflammatory symptoms similar to Kawasaki disease after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and is commonly observed in children aged 8-10 years. Primary therapeutic medications for MIS-C are intravenous immunoglobulins and glucocorticoids. It has been reported that biologics, such as IL-1 receptor antagonist anakinra, IL-6 receptor antagonist tocilizumab, and TNF-α receptor antagonist infliximab, can be used as an option for critically ill patients. This article elaborates on the mechanism of action of the above biologics and discusses the efficacy and safety biologics in the treatment of MIS-C after SARS-CoV-2 infection, in order to provide methods for the treatment of MIS-C with severe symptoms.

Vitamin B6 prevents isocarbophos-induced vascular dementia in rats through N-methyl-D-aspartate receptor signaling.

BACKGROUND: We have previously reported that the long-term exposure of organophosphorus induces vascular dementia (VD) in rats. As a coenzyme, vitamin B6 is mainly involved in the regulation of metabolisms. Whether vitamin B6 improves VD remains unknown. METHODS: The model of VD was induced by feeding rats with isocarbophos (0.5 mg/kg per two day, 12 weeks). The blood flow of the posterior cerebral artery (PCA) in rat was assessed by transcranial Doppler (TCD). The learning and memory were evaluated by the Morris Water Maze (MWM) test. RESULTS: Administration of vitamin B6 increased the blood flow in the right and left posterior cerebral arteries and improved the functions of learning and memory in isocarbophos-treated rats. Vitamin B6 increased the protein levels of N-methyl-D-aspartate receptor (NMDAR) 2B, postsynaptic densities (PSDs) protein 95, and calmodulin-dependent protein kinase II (CaMK-II) in the hippocampus, which were decreased by isocarbophos in rats. Morphological analysis by light microscope and electronic microscope indicated disruptions of the hippocampus caused by isocarbophos were normalized by vitamin B6. Importantly, the antagonist of NMDAR signaling by eliprodil abolished these beneficial effects produced by vitamin B6 on PCA blood flow, learning, memory, and hippocampus structure in rats, as well as the protein expression of NMDAR 2B, PSDs protein 95, and CaMK-II in the hippocampus. CONCLUSION: Vitamin B6 activates NMDAR signaling to prevent isocarbophos-induced VD in rats.

Negative feedback regulation between microRNA let-7g and LOX-1 mediated hypoxia-induced PASMCs proliferation.

BACKGROUND: Pulmonary hypertension (PH) is a proliferative disorder associated with enhanced proliferation and suppressed apoptosis of pulmonary artery smooth muscle cells (PASMCs). Our lately study demonstrated that let-7g inhibited hypoxia-induced proliferation of PASMCs via repressing c-myc-Bmi-1-p16 signaling pathway. However, the upstream of let-7g has not yet been fully defined. Previous studies have shown that LOX-1, a target of let-7g, could also regulate the expression of let-7g in human aortic endothelial cells. In this present study, we aimed to investigate whether there is a negative feedback regulation between microRNA let-7g and LOX-1 in hypoxia-induced proliferation of PASMCs. METHODS: SD Rats were exposed to hypoxia (10% O2, 3 weeks) to induce PH. HE staining was used to evaluate pulmonary artery remodeling. in situ hybridization and immunohistochemistry were performed to assess the expression and distribution of let-7g and LOX-1, respectively. MTS, EDU and flow cytometry were performed to evaluate PASMCs proliferation. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting were conducted to assess the expression of let-7g, LOX-1, calpain-1,-2,-4, and OCT-1. RESULTS: The expression of let-7g was significantly down-regulated in pulmonary arteries of hypoxia-induced PH rats accompanied by pulmonary vascular remodeling, whereas let-7g mimic inhibited hypoxia-induced proliferation of PASMCs and up-regulation of LOX-1 expression. LOX-1 blocking reversed hypoxia-induced down-regulation of let-7g expression. Calpains, protein kinase C and OCT-1 were involved in negative feedback regulation between let-7g and LOX-1. CONCLUSION: Negative feedback regulation between let-7g and LOX-1 mediated hypoxia-induced proliferation of in PASMCs.

Involvement of epithelial-mesenchymal transition afforded by activation of LOX-1/ TGF-ß1/KLF6 signaling pathway in diabetic pulmonary fibrosis.

BACKGROUND AND OBJECTIVE: Diabetic pulmonary fibrosis is a severe disease that increases mortality risk of diabetes. However, the molecular mechanisms leading to pulmonary fibrosis in diabetes are poorly understood. This study investigated the roles of epithelial-mesenchymal transition (EMT) and the associated molecular mechanisms in streptozotocin (STZ)-induced rat pulmonary fibrosis. METHODS: The rat model of diabetic pulmonary fibrosis was established by intraperitoneal injection of a single dose of STZ (35 mg/kg). Typical lesions of diabetic pulmonary fibrosis were observed 8 weeks after STZ injection by hematoxylin-eosin (HE) and Masson staining. Human bronchial epithelial cells (HBECs) and A549 cells were treated by high glucose. Gene or protein expression was measured by real-time PCR, Western blot, immunohistochemistry or immunofluorescence. The knockdown of lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) or transforming growth factor-ß1 (TGF-ß1) was conducted by siRNA. RESULTS: Activation of EMT was observed in lung tissues of STZ-induced diabetic rats, exhibiting a loss in the epithelial cell marker E-cadherin and an increase in the mesenchymal marker Vimentin. The protein and mRNA levels of LOX-1, TGF-ß1 and krüppel-like factor 6 (KLF6) in the lung tissues were increased. Incubation of HBECs and A549 cells with high glucose activated EMT and induced an increase in LOX-1, TGF-ß1 and KLF-6 expression. LOX-1 siRNA inhibited high glucose-induced EMT in HBECs and A549 cells, which correlated with the reduction of TGF-ß1. TGF-ß1 siRNA decreased the expression of LOX-1 and KLF6. CONCLUSIONS: EMT was involved in the pathological process of diabetic pulmonary fibrosis, which was activated by LOX-1/TGF-ß1/KLF6 signaling pathway.

Chronic administration of isocarbophos induces vascular cognitive impairment in rats.

Vascular dementia, being the most severe form of vascular cognitive impairment (VCI), is caused by cerebrovascular disease. Whether organophosphorus causes VCI remains unknown. Isocarbophos (0.5 mg/kg per 2 days) was intragastrically administrated to rats for 16 weeks. The structure and function of cerebral arteries were assayed. The learning and memory were evaluated by serial tests of step-down, step-through and morris water maze. Long-term administration of isocarbophos reduced the hippocampal acetylcholinesterase (AChE) activity and acetylcholine (ACh) content but did not alter the plasma AChE activity, and significantly damaged the functions of learning and memory. Moreover, isocarbophos remarkably induced endothelial dysfunction in the middle cerebral artery and the expressions of ICAM-1 and VCAM-1 in the posterior cerebral artery. Morphological analysis by light microscopy and electron microscopy indicated disruptions of the hippocampus and vascular wall in the cerebral arteries from isocarbophos-treated rats. Treatment of isocarbophos injured primary neuronal and astroglial cells isolated from rats. Correlation analysis demonstrated that there was a high correlation between vascular function of cerebral artery and hippocampal AChE activity or ACh content in rats. In conclusion, chronic administration of isocarbophos induces impairments of memory and learning, which is possibly related to cerebral vascular dysfunction.

MiR-590-5p-meidated LOX-1 upregulation promotes Angiotensin II-induced endothelial cell apoptosis.

BACKGROUND: Endothelial cell apoptosis contributes to cardiovascular diseases such as hypertension, atherosclerosis. MicroRNA regulates endothelial cell function but its role in endothelial cell apoptosis remains to be fully elucidated. This study aims to investigate the role of miR-590-5p in endothelial cell apoptosis and dissect the underlying mechanisms. METHODS: Flow cytometric analysis, Hoechst 33258 staining and Western blotting were performed to evaluate human umbilical vein endothelial cell (HUVEC) apoptosis induced by Angiotensin (Ang) II. Western blotting and real-time quantitative PCR were conducted to assess the expression of LOX-1. DCFH-DA staining was carried out to measure the generation of reactive oxygen species (ROS). RESULTS: Ang II-induced HUVEC apoptosis was accompanied by downregulation of miR-590-5p; administration of miR-590-5p mimics attenuated HUVEC apoptosis and decreased ROS generation, as indicated by reduced fraction of apoptotic HUVECs and decreased caspase-3 activity. LOX-1 expression was increased by Ang II, and miR-590-5p mimics reduced LOX-1 expression in HUVECs in the absence or presence of Ang II. Pharmacologic or genetic block of LOX-1 with small interference RNA or TS92 (LOX-1 neutralizing antibody) significantly ameliorated HUVEC apoptosis, as evidenced by reduced number of apoptotic HUVECs, inhibited caspase-3 activation and suppressed mitochondrial cytochrome C release. Moreover, LOX-1 siRNA or TS92 treatment dramatically reduced ROS production in HUVECs treated with Ang II. CONCLUSION: Our data demonstrated that miR-590-5p downregulation promoted Ang II-induced endothelial cell apoptosis by elevating LOX-1 expression and consequently increasing ROS generation. Thus, restoration of miR-590-5p or block of LOX-1 could be therapeutically exploited to alleviate endothelial cell apoptosis.

Calcitonin gene-related peptide down-regulates bleomycin-induced pulmonary fibrosis.

We have found that eIF3a plays an important role in bleomycin-induced pulmonary fibrosis, and up-regulation of eIF3a induced by TGF-ß1 is mediated via the ERK1/2 pathway. Whether ERK1/2 - eIF3a signal pathway is involved in calcitonin gene-related peptide (CGRP)-mediated pathogenesis of bleomycin-induced pulmonary fibrosis remains unknown. Pulmonary fibrosis was induced by intratracheal instillation of bleomycin (5 mg/kg) in rats. Primary pulmonary fibroblasts were cultured to investigate the proliferation by BrdU incorporation method and flow cytometry. Sensory CGRP depletion by capsaicin exacerbated bleomycin-induced pulmonary fibrosis in rats, as shown by a significant disturbed alveolar structure, marked thickening of the interalveolar septa and dense interstitial infiltration by inflammatory cells and fibroblasts, accompanied with increased expression of TGF-ß1, eIF3a, phosphorylated ERK1/2, α-SMA, collagen I, and collagen III. Exogenous application of CGRP significantly inhibited TGF-ß1-induced proliferation and differentiation of pulmonary fibroblasts concomitantly with decreased expression of eIF3a, phosphorylated ERK1/2, α-SMA, collagen I, and collagen III. These effects of CGRP were abolished in the presence of CGRP8-37. These results suggest that endogenous CGRP is related to the development of pulmonary fibrosis induced by bleomycin, and the inhibitory effect of CGRP on proliferation of lung fibroblasts involves the ERK1/2 - eIF3a signaling pathway.

Long Non-Coding RNA Urothelial Carcinoma Associated 1 (UCA1): Insight into Its Role in Human Diseases.

Long non-coding RNA (lncRNA) is a type of DNA transcript that is longer than 200 nucleotides (nt). They do not encode proteins, but they control gene expression on various levels. Long non-coding RNA metastasis-associated urothelial carcinoma associated 1 (UCA1) was confirmed to play an important role in the occurrence and development of many tumor and non-tumor diseases. UCA1 mainly interacts with proteins in the nucleus, regulating gene expression in transcription and post-transcription. UCA1 is highly expressed in tumor tissue, and therefore can be related to clinical parameters. It may regulate tumor cell proliferation, invasion, apoptosis, and migration, so UCA1 can be applied in clinical prognosis and targeted therapy. This review mainly elaborates the roles of UCA1 in tumor diseases of the respiratory, digestive, reproductive, and urinary systems; and in non-tumor diseases.

Accelerated onset of senescence of endothelial progenitor cells in patients with type 2 diabetes mellitus: role of dimethylarginine dimethylaminohydrolase 2 and asymmetric dimethylarginine.

The risk of cardiovascular complications in diabetic patients is mainly associated with endothelial dysfunction. Reduced number of EPCs and impaired function of EPCs in diabetes result in imbalance of endothelial homeostasis and dysfunction of vessels. In patients with diabetes mellitus, plasma levels of asymmetric dimethylarginine (ADMA) were elevated, while the expression and activity of dimethylarginine dimethylaminohydrolase (DDAH) were reduced. In the present study, we investigated the role of the DDAH2/ADMA pathway in the senescence of EPCs in type 2 diabetic patients and cultured EPCs treated with high glucose. The results showed that the percentage of senescent EPCs increased while the expression of DDAH2 decreased concomitantly with an increase in the plasma levels of ADMA in patients with type 2 diabetes mellitus (T2DM). Similar results were seen in cultured EPCs treated with high glucose. Exogenous application of ADMA accelerated the senescence of EPCs in a dose-dependent manner, and overexpression of DDAH2 inhibited high glucose-induced EPCs senescence. In addition, it has also been reported that DDAH/ADMA pathway is regulated by silent information regulator 1 (SIRT1) in endothelial cell. In the present study, we found decreased expression of SIRT1 both in T2DM patients and EPCs pretreated with high glucose. And resveratrol (activating SIRT1) inhibited high glucose-induced EPCs senescence by upregulating the expression of DDAH2 and decreasing the levels of ADMA. Taken together, we concluded that DDAH2/ADMA is involved in the accelerated senescence of EPCs in diabetes, which is associated with the activation of SIRT1.

Nuclear cardiac myosin light chain 2 modulates NADPH oxidase 2 expression in myocardium: a novel function beyond muscle contraction.

Recent studies demonstrated that NADPH oxidase 2 (NOX2) expression in myocardium after ischemia-reperfusion (IR) is significantly upregulated. However, the underlying mechanisms remain unknown. This study aims to determine if nuclear cardiac myosin light chain 2 (MYL2), a well-known regulatory subunit of myosin, functions as a transcription factor to promote NOX2 expression following myocardial IR in a phosphorylation-dependent manner. We examined the phosphorylation status of nuclear MYL2 (p-MYL2) in a rat model of myocardial IR (left main coronary artery subjected to 1 h ligation and 3 h reperfusion) injury, which showed IR injury and upregulated NOX2 expression as expected, accompanied by elevated H2O2 and nuclear p-MYL2 levels; these effects were attenuated by inhibition of myosin light chain kinase (MLCK). Next, we explored the functional relationship of nuclear p-MYL2 with NOX2 expression in H9c2 cell model of hypoxia-reoxygenation (HR) injury. In agreement with our in vivo findings, HR treatment increased apoptosis, NOX2 expression, nuclear p-MYL2 and H2O2 levels, and the increases were ameliorated by inhibition of MLCK or knockdown of MYL2. Finally, molecular biology techniques including co-immunoprecipitation (Co-IP), chromatin immunoprecipitation (ChIP), DNA pull-down and luciferase reporter gene assay were utilized to decipher the molecular mechanisms. We found that nuclear p-MYL2 binds to the consensus sequence AGCTCC in NOX2 gene promoter, interacts with RNA polymerase II and transcription factor IIB to form a transcription preinitiation complex, and thus activates NOX2 gene transcription. Our results demonstrate that nuclear MYL2 plays an important role in IR injury by transcriptionally upregulating NOX2 expression to enhance oxidative stress in a phosphorylation-dependent manner.

Regulation of endothelial progenitor cell differentiation and function by dimethylarginine dimethylaminohydrolase 2 in an asymmetric dimethylarginine-independent manner.

Endothelial progenitor cells (EPCs) are involved in the repair of vessels and angiogenesis and are useful in the treatment of ischemic diseases. The dimethylarginine dimethylaminohydrolase (DDAH)/asymmetric dimethylarginine (ADMA) pathway is regulated by silent information regulator 1 (SIRT1), leading to the senescence of endothelial cells (ECs). Here, we demonstrated that peripheral blood EPCs predominantly expressed DDAH2 that increased with EPC differentiation. EPC senescence and dysfunction were induced on interruption of DDAH2 expression, whereas the mRNA expression of vascular endothelial growth factor (VEGF) and kinase-domain insert containing receptor (KDR) were downregulated. Moreover, SIRT1 expression increased with EPC differentiation. Interruption of SIRT1 inhibited DDAH2, VEGF, and KDR expression, but had no effect on the level of ADMA. From our data, we concluded that DDAH2 is involved in the differentiation of EPCs and regulates the senescence and function of EPCs through the VEGF/KDR pathway by activation of SIRT1.

Inhibition of NOX/VPO1 pathway and inflammatory reaction by trimethoxystilbene in prevention of cardiovascular remodeling in hypoxia-induced pulmonary hypertensive rats.

Recent studies show that resveratrol exerts beneficial effects on prevention of pulmonary hypertension. This study is performed to explore the effects of trimethoxystilbene, a novel resveratrol analog, on rat pulmonary vascular remodeling and right ventricular hypertrophy in hypoxia-induced pulmonary arterial hypertension (PAH) and the underlying mechanisms. Sprague-Dawley rats were placed in a chamber and exposed to 10% O(2) continuously for 4 weeks to induce PAH. The effects of trimethoxystilbene (5 or 10 mg/kg per day, intragastric [i.g.]) and resveratrol (as a positive control, 25 mg/kg per day, i.g.) on hypoxia-induced PAH vascular remodeling and right ventricle hypertrophy were evaluated. At the end of experiments, the index for pulmonary vascular remodeling and right ventricle hypertrophy, inflammatory cell infiltration in lung tissue, the plasma levels and lung tissue contents of hydrogen peroxide (H(2)O(2)), the mRNA and protein levels for NADPH oxidases (NOX2, NOX4) and vascular peroxidase 1 (VPO1) in pulmonary artery or right ventricle were measured. The results showed that trimethoxystilbene treatment significantly attenuated hypoxia-induced pulmonary vascular remodeling (such as decrease in the ratio of wall thickness to vessel external diameter) and right ventricle hypertrophy (such as decrease in the ratio of right ventricle weight to the length of the tibia), accompanied by downregulation of NOX2, NOX4, and VPO1 expression in pulmonary artery or right ventricle, decrease in H(2)O(2) production and inflammatory cell infiltration in lung tissue. Trimethoxystilbene is able to prevent pulmonary vascular remodeling and right ventricle hypertrophy in hypoxia-induced rat model of PAH, which is related to inhibition of the NOX/VPO1 pathway-mediated oxidative stress and the inflammatory reaction.

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

Fluorofenidone (AKF-PD) is a novel pyridone derivate that targets transforming growth factor-ß1 (TGF-ß1) signaling. Previous studies have proven that AKF-PD functions as an antifibrotic agent in pulmonary fibrosis and renal fibrosis models. Activated TGF-ß1 signaling is thought to be a major feature of pulmonary hypertension (PH). TGF-ß1 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-ß1, 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-ß1 level was significantly down-regulated by AKF-PD both in vivo and in vitro. Furthermore, hypoxia- and TGF-ß1-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-ß1 expression, PASMC proliferation, and the extracellular matrix.

Inhibitory effect of reinioside C on vascular smooth muscle cells proliferation induced by angiotensin II via inhibiting NADPH oxidase-ROS-ENK1/2-NF-kappaB-AP-1 pathway.

The proliferation of vascular smooth muscle cells (VSMCs) induced by angiotensin II (Ang II) plays a vital role in the pathogenesis of arteriosclerosis and restenosis. In the present study, the effect of reinioside C, a main active ingredient of Polygala fallax Hemsl, on proliferation of VSMCs induced by Ang II was investigated. It was found that Ang II (1 microM) markedly stimulated proliferation of VSMCs. Pretreatment of reinioside C (3, 10 or 30 microM) concentration-dependently inhibited the proliferative effect of Ang II. To determine the possible mechanism, NADPH oxidase subunits (Nox-1, Nox-4) mRNA expression, intracellular ROS level, phosphorylation of ERK1/2, NF-kappaB activity, and mRNA expression of AP-1 subunits (c-fos, c-jun) and c-myc were measured. The results demonstrated that reinioside C attenuated Ang II-induced NADPH oxidase mRNA expression, generation of ROS, ERK1/2 phosphorylation, activation of NF-kappaB, and mRNA expression of AP-1 and c-myc in VSMCs in a concentration-dependent manner. The effects of Ang II were also inhibited by diphenyleneiodonium (DPI, the NADPH oxidase inhibitor), PD98059 (the ERK1/2 inhibitor) and pyrrolidine dithiocarbamate (PDTC, the NF-kappaB inhibitor). These results suggest reinioside C attenuates Ang II-induced proliferation of VSMCs by inhibiting NADPH oxidase-ROS-ERK1/2-NF-kappaB-AP-1 pathway.

The Weakened Interaction Between HECTD4 and GluN2B in Ischemic Stroke Promotes Calcium Overload and Brain Injury Through a Mechanism Involving the Decrease of GluN2B and MALT1 Ubiquitination.

Glutamate receptor ionotropic NMDA 2B (GluN2B) plays an essential role in calcium overload during excitotoxicity. Reverse-phase nano-liquid chromatography-tandem mass spectrometry has revealed an interaction between GluN2B and HECT domain E3 ubiquitin protein ligase 4 (HECTD4), an E3 ubiquitin ligase highly expressed in the brain. As a potential substrate for HECTD4, mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) acts as a scaffold with hydrolysis activity. This study explores the relationship between HECTD4, GluN2B, and MALT1, focusing on their role in brain injury in ischemic stroke. Rats were subjected to 2 h-ischemia followed by 24-h reperfusion to establish an ischemic stroke model. We observed the downregulation of HECTD4 and the upregulation of MALT1. Additionally, an increased GluN2B phosphorylation was concomitant with weakened interactions between HECTD4 and GluN2B, followed by decreased striatal-enriched protein phosphatase (STEP61). Knockdown of HECTD4 exacerbated hypoxia- or NMDA-induced injury in nerve cells coincident with a decrease in GluN2B and MALT1 ubiquitination, and an increase in GluN2B phosphorylation as well as an increase in intracellular calcium level, which were counteracted by MALT1 siRNA. Blockage of MALT1 with its inhibitor or siRNA reduced STEP61 degradation, accompanied by a decrease in GluN2B phosphorylation, intracellular calcium concentration, and brain cell injury, which were reversed by overexpression of MALT1. Based on these observations, we conclude that the downregulation of HECTD4 in ischemic stroke rat brain accounts for calcium overload and brain injury due to activating GluN2B directly and indirectly through a mechanism involving the reduced ubiquitination of GluN2B and MALT1, respectively.

Plasma exosomes confer hypoxic pulmonary hypertension by transferring LOX-1 cargo to trigger phenotypic switching of pulmonary artery smooth muscle cells.

The pulmonary vascular remodeling (PVR), the pathological basis of pulmonary hypertension (PH), entails pulmonary artery smooth muscle cells (PASMCs) phenotypic switching, but appreciation of the underlying mechanisms is incomplete. Exosomes, a novel transfer machinery enabling delivery of its cargos to recipient cells, have been recently implicated in cardiovascular diseases including PH. The two critical questions of whether plasma-derived exosomes drive PASMCs phenotypic switching and what cargo the exosomes transport, however, remain unclear. Herein, by means of transmission electron microscopy and protein detection, we for the first time, characterized lectin like oxidized low-density lipoprotein receptor-1 (LOX-1) as a novel cargo of plasma-derived exosomes in PH. With LOX-1 knockout (Olr1-/-) rats-derived exosomes, we demonstrated that exosomal LOX-1 could be transferred into PASMCs and thus elicited cell phenotypic switching. Of importance, Olr1-/- rats exhibited no cell phenotypic switching and developed less severe PH, but administration of wild type rather than Olr1-/- exosomes to Olr1-/- rats recapitulated the phenotype of PH with robust PASMCs phenotypic switching. We also revealed that exosomal LOX-1 triggered PASMCs phenotypic switching, PVR and ultimately PH via ERK1/2-KLF4 signaling axis. This study has generated proof that plasma-derived exosomes confer PH by delivering LOX-1 into PASMCs. Hence, exosomal LOX-1 represents a novel exploitable target for PH prevention and treatment.

Dimethylarginine dimethylaminohydrolase 1 regulates nerve growth factor-promoted differentiation of PC12 cells in a nitric oxide-dependent but asymmetric dimethylargenine-independent manner.

There are significant morphological and biochemical alterations during nerve growth factor (NGF)-promoted neuronal differentiation, and the process is regulated by molecules, including nitric oxide (NO). Dimethylarginine dimethylaminohydrolase (DDAH) is thought to play a critical role in regulating NO production via hydrolyzing the endogenous NO synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA). Thus, we tested the role of DDAH in NGF-promoted differentiation of PC12 (pheochromocytoma) cells. The present results show that both mRNA and protein levels of DDAH1 were increased, whereas those of DDAH2 were decreased, during NGF-promoted cell differentiation. Both the DDAH activity and the ADMA level in cultured medium were unchanged in this process. NGF promoted neurite formation and induced the expression of microtubule-associated protein 2 (MAP2), a neuronal marker, which were both significantly repressed by DDAH1 silence with small interfering RNA but not by DDAH2 silence. The expressions of three isoforms of NOS were markedly upregulated after NGF stimulation with a time course similar to that of DDAH1, which were attenuated by DDAH1 silence. Conversely, overexpression of DDAH1 accelerated neurite formation in PC12 cells, concomitantly with upregulating the expression of three NOS isoforms. In summary, our data reveal the critical regulatory effect of DDAH1 on NGF-promoted differentiation of PC12 cells in an NOS/NO-dependent but ADMA-independent manner.

A novel pathway of NADPH oxidase/vascular peroxidase 1 in mediating oxidative injury following ischemia-reperfusion.

Vascular peroxidase 1 (VPO1) can utilize reactive oxygen species (ROS) generated from NADPH oxidase (NOX) to catalyze peroxidative reactions. This study was performed to identify a novel pathway of NOX/VPO1 in mediating the oxidative injury following myocardial ischemia reperfusion (IR). In a rat model of myocardial IR, the infarct size, serum creatine kinase (CK) activity, apoptosis, NOX activity, NOX2 and VPO1 expression were measured. In a cell (rat heart-derived H9c2 cells) model of hypoxia/reoxygenation (HR), the apoptosis, NOX activity, NOX2 and VPO1 expression, and H(2)O(2) and HOCl levels were examined. In vivo, IR caused 54.8 ± 1.7 % infarct size in myocardium accompanied by elevated activities of CK, caspase-3 and NOX, up-regulated VPO1 expression and high numbers of myocardial apoptotic cells; these effects were attenuated by pretreatment with the inhibitor of NOX. In vitro, inhibition of NOX or silencing of NOX2 or VPO1 expression significantly suppressed HR-induced cellular apoptosis concomitantly with decreased HOCl production. Inhibition of NOX or silencing of NOX2 led to a decrease in H(2)O(2) production accompanied by a decrease in VPO1 expression and HOCl production. However, silencing of VPO1 expression did not affect NOX2 expression and H(2)O(2) production. H(2)O(2)-induced VPO1 expression was partially reversed by JNK or p38 MAPK inhibitor. Our results demonstrate a novel pathway of NOX2/VPO1 in myocardium, where VPO1 coordinates with NOX2 and amplifies the role of NOX-derived ROS in oxidative injury following IR.