Membrane raft redox signalling contributes to endothelial dysfunction and vascular remodelling of thoracic aorta in angiotensin II-infused rats.

NEW FINDINGS: What is the central question of this study? Is the membrane raft redox signalling pathway involved in blood pressure increase, endothelial dysfunction and vascular remodelling in an angiotensin II-induced hypertensive animal model? What is the main finding and its importance? The membrane raft redox signalling pathway was involved in endothelial dysfunction and medial remodelling in angiotensin II-induced hypertension. ABSTRACT: The membrane raft (MR) redox pathway is characterized by NADPH oxidase activation via the clustering of its subunits through lysosome fusion and the activation of acid sphingomyelinase (ASMase). Our previous study shows that the MR redox signalling pathway is associated with angiontensin II (AngII)-induced production of reactive oxygen species (ROS) and endothelial dysfunction in rat mesenteric arteries. In the present study, we hypothesized that this signalling pathway is involved in blood pressure increase, endothelial dysfunction and vascular remodelling in an AngII-induced hypertensive animal model. Sixteen-week-old male Sprague-Dawley rats were subjected to AngII infusion for 2 weeks with or without treatment with the lysosome fusion inhibitor bafilomycin A1 and ASMase inhibitor amitriptyline. After treatments, aortas were harvested for further study. The results showed that the MR redox signalling pathway was activated as indicated by the increase of MR formation, ASMase activity and ROS production in aorta from AngII-infused rats compared with that from control rats. MR formation and ROS production were significantly inhibited in thoracic aorta from AngII-induced rats treated with bafilomycin A1 and amitriptyline. Both treatments significantly attenuated blood pressure increase, endothelial dysfunction and vascular remodelling including medial hypertrophy, and increased collagen and fibronectin deposition in thoracic aortas from AngII-infused rats. Finally, both treatments significantly prevented the increase of inflammatory factors including monocyte chemotactic protein 1, intercellular adhesion molecule 1 and tumour necrosis factor α in thoracic aorta from AngII-infused rats. In conclusion, the present study demonstrates that the MR redox signalling pathway was involved in endothelial dysfunction and medial remodelling in AngII-induced hypertension.

Membrane rafts-redox signalling pathway contributes to renal fibrosis via modulation of the renal tubular epithelial-mesenchymal transition.

KEY POINTS: Membrane rafts (MRs)-redox signalling pathway is activated in response to transforming growth factor-ß1 (TGF-ß1) stimulation in renal tubular cells. This pathway contributes to TGF-1ß-induced epithelial-mesenchymal transition (EMT) in renal tubular cells. The the MRs-redox signalling pathway is activated in renal tubular cells isolated from angiotensin II (AngII)-induced hypertensive rats. Inhibition of this pathway attenuated renal inflammation and fibrosis in AngII-induced hypertension. ABSTRACT: The membrane rafts (MRs)-redox pathway is characterized by NADPH oxidase subunit clustering and activation through lysosome fusion, V-type proton ATPase subunit E2 (encoded by the Atp6v1e2 gene) translocation and sphingomyelin phosphodiesterase 1 (SMPD1, encoded by the SMPD1 gene) activation. In the present study, we hypothesized that the MRs-redox-derived reactive oxygen species (ROS) are involved in renal inflammation and fibrosis by promoting renal tubular epithelial-mesenchymal transition (EMT). Results show that transforming growth factor-ß1 (TGF-ß1) acutely induced MR formation and ROS production in NRK-52E cells, a rat renal tubular cell line. In addition, transfection of Atp6v1e2 small hairpin RNAs (shRNA) and SMPD1 shRNA attenuated TGF-ß1-induced changes in EMT markers, including E-cadherin, α-smooth muscle actin (α-SMA) and fibroblast-specific protein-1 (FSP-1) in NRK-52E cells. Moreover, Erk1/2 activation may be a downstream regulator of the MRs-redox-derived ROS, because both shRNAs significantly inhibited TGF-ß1-induced Erk1/2 phosphorylation. Further in vivo study shows that the renal tubular the MRs-redox signalling pathway was activated in angiotensin II (AngII)-induced hypertension, as indicated by the increased NADPH oxidase subunit Nox4 fraction in the MR domain, SMPD1 activation and increased ROS content in isolated renal tubular cells. Finally, renal transfection of Atp6v1e2 shRNA and SMPD1 shRNA significantly prevented renal fibrosis and inflammation, as indicated by the decrease of α-SMA, fibronectin, collagen I, monocyte chemoattractant protein-1 (MCP-1), intercellular cell adhesion molecule-1 (ICAM-1) and tumour necrosis factor-α (TNF-α) in kidneys from AngII-infused rats. It was concluded that the the MRs-redox signalling pathway is involved in TGF-ß1-induced renal tubular EMT and renal inflammation/fibrosis in AngII-induced hypertension.

Protease-activated receptor 1 and 2 contribute to angiotensin II-induced activation of adventitial fibroblasts from rat aorta.

Adventitial fibroblasts (AFs) can be activated by angiotensin II (Ang II) and exert pro-fibrotic and pro-inflammatory effects in vascular remodeling. Protease-activated receptor (PAR) 1 and 2 play a significant role in fibrogenic and inflammatory diseases. The present study hypothesized that PAR1 and PAR2 are involved in Ang II-induced AF activation and contribute to adventitial remodeling. We found that direct activation of PAR1 and PAR2 with PAR1-AP and PAR2-AP led to AF activation, including proliferation and differentiation of AFs, extracellular matrix synthesis, as well as production of pro-fibrotic cytokine TGF-ß and pro-inflammatory cytokines IL-6 and MCP-1. Furthermore, PAR1 and PAR2 mediated Ang II-induced AF activation, since both PAR1 and PAR2 antagonists inhibited Ang II-induced proliferation, migration, differentiation, extracellular matrix synthesis and production of pro-fibrotic and pro-inflammatory cytokines in AFs. Finally, mechanistic study showed that Ang II, via Ang II type I receptor (AT1R), upregulated both PAR1 and PAR2 expression, and transactivated PAR1 and PAR2, as denoted by internalization of both proteins. In conclusion, our results suggest that PAR1 and PAR2 play a critical role in Ang II-induced AF activation, and this may contribute to adventitia-related pathological changes.

Hypoxia-inducible factor prolyl-hydroxylase-2 mediates transforming growth factor beta 1-induced epithelial-mesenchymal transition in renal tubular cells.

Transforming growth factor beta 1 (TGF-ß1)-induced epithelial-mesenchymal transition (EMT) in kidney epithelial cells plays a key role in renal tubulointerstitial fibrosis in chronic kidney diseases. As hypoxia-inducible factor (HIF)-1α is found to mediate TGF-ß1-induced signaling pathway, we tested the hypothesis that HIF-1α and its upstream regulator prolyl hydroxylase domain-containing proteins (PHDs) are involved in TGF-ß1-induced EMT using cultured renal tubular cells. Our results showed that TGF-ß1 stimulated EMT in renal tubular cells as indicated by the significant decrease in epithelial marker P-cadherin, and the increase in mesenchymal markers α-smooth muscle actin (α-SMA) and fibroblast-specific protein 1 (FSP-1). Meanwhile, we found that TGF-ß1 time-dependently increased HIF-1α and that HIF-1α siRNA significantly inhibited TGF-ß1-induced EMT, suggesting that HIF-1α mediated TGF-ß1 induced-EMT. Real-time PCR showed that PHD1 and PHD2, rather than PHD3, could be detected, with PHD2 as the predominant form of PHDs (PHD1:PHD2=0.21:1.0). Importantly, PHD2 mRNA and protein, but not PHD1, were decreased by TGF-ß1. Furthermore, over-expression of PHD2 transgene almost fully prevented TGF-ß1-induced HIF-1α accumulation and EMT marker changes, indicating that PHD2 is involved in TGF-ß1-induced EMT. Finally, Smad2/3 inhibitor SB431542 prevented TGF-ß1-induced PHD2 decrease, suggesting that Smad2/3 may mediate TGF-ß1-induced EMT through PHD2/HIF-1α pathway. It is concluded that TGF-ß1 decreased PHD2 expression via an Smad-dependent signaling pathway, thereby leading to HIF-1α accumulation and then EMT in renal tubular cells. The present study suggests that PHD2/HIF-1α is a novel signaling pathway mediating the fibrogenic effect of TGF-ß1, and may be a new therapeutic target in chronic kidney diseases.

Lysosome fusion to the cell membrane is mediated by the dysferlin C2A domain in coronary arterial endothelial cells.

Dysferlin has recently been reported to participate in cell membrane repair in muscle and other cells through lysosome fusion. Given that lysosome fusion is a crucial mechanism that leads to membrane raft clustering, the present study attempted to determine whether dysferlin is involved in this process and its related signalling, and explores the mechanism underlying dysferlin-mediated lysosome fusion in bovine coronary arterial endothelial cells (CAECs). We found that dysferlin is clustered in membrane raft macrodomains after Fas Ligand (FasL) stimulation as detected by confocal microscopy and membrane fraction flotation. Small-interfering RNA targeted to dysferlin prevented membrane raft clustering. Furthermore, the translocation of acid sphingomyelinase (ASMase) to membrane raft clusters, whereby local ASMase activation and ceramide production--an important step that mediates membrane raft clustering--was attenuated. Functionally, silencing of the dysferlin gene reversed FasL-induced impairment of endothelium-dependent vasodilation in isolated small coronary arteries. By monitoring fluorescence quenching or dequenching, silencing of the dysferlin gene was found to almost completely block lysosome fusion to plasma membrane upon FasL stimulation. Further studies to block C2A binding and silencing of AHNAK (a dysferlin C2A domain binding partner), showed that the dysferlin C2A domain is required for FasL-induced lysosome fusion to the cell membrane, ASMase translocation and membrane raft clustering. We conclude that dysferlin determines lysosome fusion to the plasma membrane through its C2A domain and it is therefore implicated in membrane-raft-mediated signaling and regulation of endothelial function in coronary circulation.

Overexpression of HIF prolyl-hydoxylase-2 transgene in the renal medulla induced a salt sensitive hypertension.

Renal medullary hypoxia-inducible factor (HIF)-1α and its target genes, such as haem oxygenase and nitric oxide synthase, have been indicated to play an important role in the regulation of sodium excretion and blood pressure. HIF prolyl hydroxylase domain-containing proteins (PHDs) are major enzymes to promote the degradation of HIF-1α. We recently reported that high salt intake suppressed the renal medullary PHD2 expression and thereby activated HIF-1α-mediated gene regulation in the renal medulla in response to high salt. To further define the functional role of renal medullary PHD2 in the regulation of renal adaptation to high salt intake and the longer term control of blood pressure, we transfected PHD2 expression plasmids into the renal medulla in uninephrectomized rats and determined its effects on pressure natriuresis, sodium excretion after salt overloading and the long-term control of arterial pressure after high salt challenge. It was shown that overexpression of PHD2 transgene increased PHD2 levels and decreased HIF-1α levels in the renal medulla, which blunted pressure natriuresis, attenuated sodium excretion, promoted sodium retention and produced salt sensitive hypertension after high salt challenge compared with rats treated with control plasmids. There was no blood pressure change in PHD2-treated rats that were maintained in low salt diet. These results suggested that renal medullary PHD2 is an important regulator in renal adaptation to high salt intake and a deficiency in PHD2-mediated molecular adaptation in response to high salt intake in the renal medulla may represent a pathogenic mechanism producing salt sensitive hypertension.

Reconstitution of lysosomal NAADP-TRP-ML1 signaling pathway and its function in TRP-ML1(-/-) cells.

It is well known that the mutation of TRP-ML1 (transient receptor potential-mucolipin-1) causes mucolipidosis IV, a lysosomal storage disease. Given that lysosomal nicotinic acid adenine dinucleotide phosphate (NAADP)-Ca(2+) release channel activity is associated with TRP-ML1, the present study was designed to test the hypothesis that NAADP regulates lysosome function via activation of TRP-ML1 channel activity. Using lysosomal preparations from wild-type (TRP-ML1(+/+)) human fibroblasts, channel reconstitution experiments demonstrated that NAADP (0.01-1.0 µM) produced a concentration-dependent increase in TRP-ML1 channel activity. This NAADP-induced activation of TRP-ML1 channels could not be observed in lysosomes from TRP-ML1(-/-) cells, but was restored by introducing a TRP-ML1 transgene into these cells. Microscopic Ca(2+) fluorescence imaging showed that NAADP significantly increased intracellular Ca(2+) concentration to 302.4 ± 74.28 nM (vs. 180 ± 44.13 nM of the basal) in TRP-ML1(+/+) cells, but it had no effect in TRP-ML1(-/-) cells. If a TRP-ML1 gene was transfected into TRP-ML1(-/-) cells, the Ca(2+) response to NAADP was restored to the level comparable to TRP-ML1(+/+) cells. Functionally, confocal microscopy revealed that NAADP significantly enhanced the dynamic interaction of endosomes and lysosomes and the lipid delivery to lysosomes in TRP-ML1(+/+) cells. This functional action of NAADP was abolished in TRP-ML1(-/-) cells, but restored after TRP-ML1 gene was rescued in these cells. Our results suggest that NAADP increases lysosomal TRP-ML1 channel activity to release Ca(2+), which promotes the interaction of endosomes and lysosomes and thereby regulates lipid transport to lysosomes. Failure of NAADP-TRP-ML1 signaling may be one of the important mechanisms resulting in intracellular lipid trafficking disorder and consequent mucolipidosis.

Visfatin-induced lipid raft redox signaling platforms and dysfunction in glomerular endothelial cells.

Adipokines have been reported to contribute to glomerular injury during obesity or diabetes mellitus. However, the mechanisms mediating the actions of various adipokines on the kidney remained elusive. The present study was performed to determine whether acid sphingomyelinase (ASM)-ceramide associated lipid raft (LR) clustering is involved in local oxidative stress in glomerular endothelial cells (GECs) induced by adipokines such as visfatin and adiponectin. Using confocal microscopy, visfatin but not adiponectin was found to increase LRs clustering in the membrane of GECs in a dose and time dependent manner. Upon visfatin stimulation ASMase activity was increased, and an aggregation of ASMase product, ceramide and NADPH oxidase subunits, gp91(phox) and p47(phox) was observed in the LR clusters, forming a LR redox signaling platform. The formation of this signaling platform was blocked by prior treatment with LR disruptor filipin, ASMase inhibitor amitriptyline, ASMase siRNA, gp91(phox) siRNA and adiponectin. Corresponding to LR clustering and aggregation of NADPH subunits, superoxide (O(2)(-)) production was significantly increased (2.7 folds) upon visfatin stimulation, as measured by electron spin resonance (ESR) spectrometry. Functionally, visfatin significantly increased the permeability of GEC layer in culture and disrupted microtubular networks, which were blocked by inhibition of LR redox signaling platform formation. In conclusion, the injurious effect of visfatin, but not adiponectin on the glomerular endothelium is associated with the formation of LR redox signaling platforms via LR clustering, which produces local oxidative stress resulting in the disruption of microtubular networks in GECs and increases the glomerular permeability.

SNARE-mediated rapid lysosome fusion in membrane raft clustering and dysfunction of bovine coronary arterial endothelium.

The present study attempted to evaluate whether soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) mediate lysosome fusion in response to death receptor activation and contribute to membrane raft (MR) clustering and consequent endothelial dysfunction in coronary arterial endothelial cells. By immunohistochemical analysis, vesicle-associated membrane proteins 2 (VAMP-2, vesicle-SNAREs) were found to be abundantly expressed in the endothelium of bovine coronary arteries. Direct lysosome fusion monitoring by N-(3-triethylammoniumpropyl)-4-[4-(dibutylamino)styryl]pyridinium dibromide (FM1-43) quenching demonstrated that the inhibition of VAMP-2 with tetanus toxin or specific small interfering ribonucleic acid (siRNA) almost completely blocked lysosome fusion to plasma membrane induced by Fas ligand (FasL), a well-known MR clustering stimulator. The involvement of SNAREs was further confirmed by an increased interaction of VAMP-2 with a target-SNARE protein syntaxin-4 after FasL stimulation in coimmunoprecipitation analysis. Also, the inhibition of VAMP-2 with tetanus toxin or VAMP-2 siRNA abolished FasL-induced MR clustering, its colocalization with a NADPH oxidase unit gp91(phox), and increased superoxide production. Finally, FasL-induced impairment of endothelium-dependent vasodilation was reversed by the treatment of bovine coronary arteries with tetanus toxin or VAMP-2 siRNA. VAMP-2 is critical to lysosome fusion in MR clustering, and this VAMP-2-mediated lysosome-MR signalosomes contribute to redox regulation of coronary endothelial function.

Reversal by growth hormone of homocysteine-induced epithelial-to-mesenchymal transition through membrane raft-redox signaling in podocytes.

Epithelial-to-Mesenchymal Transition (EMT) is an important pathogenic mechanism mediating glomerular injury or sclerosis in a variety of renal and systemic diseases such as hyperhomocysteinemia (hHcys). The present study was designed to test whether Hcys-induced EMT in podocytes is reversed by growth hormone (GH), a hormone regulating cell differentiation and growth and to explore the cellular and molecular mechanism mediating its action. It was found that Hcys induced significant EMT in podocytes, as shown by marked decreases in slit diaphragm-associated protein P-cadherin and zonula occludens-1 as epithelial markers and by dramatic increases in the expression of mesenchymal markers, fibroblast specific protein-1 and α-smooth muscle actin, which were detected by all examinations via immunocytochemistry, real time RT-PCR and Western blot analysis. When podocytes were treated with GH at 25 ng/mL, however, Hcys failed to induce podocyte EMT. Using electromagnetic spin resonance spectrometry, Hcys-induced superoxide (O(2).(-)) production via NADPH oxidase was found to be significantly inhibited by GH (66%). Functionally, GH was shown to substantially inhibit Hcys-induced increases in the permeability of podocyte monolayers and to block the decrease in podocin expression in these cells. In addition, NADPH oxidase subunit, gp91(phox) and GH receptors aggregated in membrane raft clusters, which produced O(2).(-) in response to Hcys and could be blocked by GH, membrane raft disruptors filipin and MCD or NADPH oxidase inhibitor, apocynin. It is concluded that Hcys-induced podocyte EMT is associated with transmembrane membrane raft-redox signaling and that GH reverses this Hcys-induced EMT protecting podocytes from functional disturbance.

Correlation Between the Evolution of Somatic Alterations During Lymphatic Metastasis and Clinical Outcome in Penile Squamous Cell Carcinoma.

Penile squamous cell carcinoma (PSCC) is a rare malignancy with poor survival after standard treatment. Although genomic alterations of PSCC have been characterized in several latest studies, the association between the formation of somatic landscape and regional lymph node metastasis (LNM), an important predictor for patient survival, has not been comprehensively investigated. Here, we collected formalin-fixed paraffin-embedded tumor tissue and matched normal samples of 32 PSCC patients, including 14 LNM patients and 18 clinically node-negative patients, to implement a whole-exome sequencing. Comparison of genomic features among different lymph node status subgroups was conducted after genomic profiling and its effects on patient survival were explored. Top-ranked recurrent gene mutants in our PSCC cohort were TP53 (13/32), NOTCH1 (12/32), CDKN2A (11/32), TTN (9/32) and FAT1 (8/32), mainly identified in the Notch, Hippo, cell cycle, TP53, RTK-RAS and PI3K pathways. While CDKN2A was confirmed to be the driver gene in all PSCC patients, certain gene mutants were significantly enriched in LNM involved patients, including TP53 (9/14 vs. 4/18, p = 0.029) and GBF1 (4/14 vs. 0/18, p = 0.028). Overall survival stratification of PSCC patients were found to be significantly correlated with mutations of three genes, including PIK3CA (Hazard ratio [HR] = 4.15, p = 0.029), CHD7 (HR = 4.82, p = 0.032) and LAMC3 (HR = 15.9, p < 0.001). PIK3CA and LAMC3 held a higher prevalence in patients with LNM compared to those without LNM (PIK3CA: 3/14 vs. 1/18, LAMC3: 2/14 vs. 1/18). Our finding demonstrated that genomic divergence exists across PSCC patients with different lymph node statuses, and it may be correlated with their survival outcome. It helps delineate somatic evolution during tumor progression and perfect potential therapeutic intervention in this disease.

Triggering role of acid sphingomyelinase in endothelial lysosome-membrane fusion and dysfunction in coronary arteries.

The present study determined whether activation of acid sphingomyelinase (ASM) drives membrane proximal lysosomes to fuse to the cell surface, facilitating membrane lipid rafts (LRs) clustering in coronary arterial endothelial cells (CAECs) and leading to endothelial dysfunction. By confocal microscopy, the activators of ASM, phosphatidylinositol (PI), and bis (monoacylglyceryl) phosphate (Bis), and an inducer of ASM, butyrate, were found to increase LRs clustering in bovine CAECs, which was blocked by lysosome fusion inhibitor vacuolin-1. However, arsenic trioxide (Ars), an inducer of de novo synthesis of ceramide, had no such effect. Similarly, vacuolin-1-blockable effects were observed using fluorescence resonance energy transfer detection. Liquid chromatography-electrospray ionization-tandem mass spectrometry analysis demonstrated that all of these treatments, even Ars, increased ceramide production in CAECs. When ASM gene was silenced, all treatments except Ars no longer increased ceramide levels. Furthermore, dynamic fluorescence monitoring in live cells showed that PI and Bis stimulated lysosome-membrane fusion in CAECs. Functionally, PI and Bis impaired endothelium-dependent vasodilation in perfused coronary arteries, which was blocked by vacuolin-1 and a lysosome function inhibitor, bafilomycine. FasL (Fas ligand), a previously confirmed lysosome fusion stimulator as a comparison, also produced a similar effect. It is concluded that ASM activation serves as a triggering mechanism and driving force, leading to fusion of membrane proximal lysosomes into LR clusters on the cell membrane of CAECs, which represents a novel mechanism mediating endothelial dysfunction during death receptor activation or other pathological situation.

The PDE1A-PKCalpha signaling pathway is involved in the upregulation of alpha-smooth muscle actin by TGF-beta1 in adventitial fibroblasts.

BACKGROUND: Increasing evidence has suggested that differentiation of adventitial fibroblasts (AFs) to myofibroblasts plays an important role in arterial remodeling. The molecular mechanisms by which myofibroblast formation is regulated still remain largely unknown. This study aimed to evaluate the role of cyclic nucleotide phosphodiesterase 1A (PDE1A) in the formation of adventitial myofibroblasts induced by transforming growth factor (TGF)-beta(1). METHODS AND RESULTS: AFs were cultured by the explant method. Western blot and immunocytochemistry were applied for alpha-smooth muscle actin (SMA) or protein kinase C (PKC) alpha protein analysis. Results showed that TGF-beta(1) upregulated PDE1A protein expression in rat aortic AFs and pharmacological inhibition of PDE1A blocked TGF-beta(1)-induced alpha-SMA expression, a marker of myofibroblast formation, suggesting that the upregulation of PDE1A may mediate TGF-beta(1)-induced AF transformation. Moreover, calphostin C (a PKC inhibitor) inhibited TGF-beta(1)-induced alpha-SMA expression, whereas phorbol-12-myristate-13-acetate (a PKC activator) induced it. Finally, the upregulation of PKCalpha expression by TGF-beta(1) was also inhibited by PDE1A inhibition. CONCLUSIONS: Taken together, our data suggest that TGFbeta(1) induces alpha-SMA expression and myofibroblast formation via a PDE1A-PKCalpha-dependent mechanism. Our study thus unveils a novel signaling mechanism underlying TGF-beta(1)-induced adventitial myofibroblast formation.

Different biomechanical properties of medial and adventitial layers of thoracic aorta in Wistar-Kyoto and spontaneously hypertensive rats.

AIM: To evaluate the biomechanical properties of thoracic aorta with or without adventitia, and to determine whether there are corresponding changes with hypertension. METHODS: Normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) at the age of 16 and 32 weeks were used. Thoracic aortic adventitial layer was mechanically separated from thoracic aorta and the adventitia-denuded artery ring was viewed as thoracic media. A load-strain curve was obtained by stretching the ring-shaped intact thoracic aorta or thoracic media with a tensile testing machine. Then, the slope of the load-stain curve at 30%-40% strains was viewed as the elastic stiffness at physiological load, whereas the slope near the breaking point was calculated as maximum stiffness. The maximum load is the load at the breaking point. RESULTS: There was no significant difference in elastic stiffness and maximum stiffness of intact thoracic aorta between SHR and age-matched WKY. The elastic stiffness of intact thoracic aorta showed no significant difference from that of thoracic media in WKY and SHR at both ages. In contrast, both maximum stiffness and maximum load were reduced in thoracic media compared with intact thoracic aorta in SHR and WKY at both ages. CONCLUSION: These results indicated that vascular adventitia contributes to maximum stiffness, but not elastic stiffness in both SHR and WKY.

Involvement of Angiotensin II Type 1 Receptor and Calcium Channel in Vascular Remodeling and Endothelial Dysfunction in Rats with Pressure Overload.

Vascular remodeling is an adaptive response to various stimuli, including mechanical forces, inflammatory cytokines and hormones. In the present study, we investigated the role of angiotensin II type 1 receptor (AT1R) and calcium channel in carotid artery remodeling in response to increased biomechanical forces by using the transverse aortic constriction (TAC) rat model. TAC was induced on ten-week-old male Sprague-Dawley rats and these models were treated with AT1R blocker olmesartan (1 mg/kg/day) or/and calcium channel blocker (CCB) amlodipine (0.5 mg/kg/day) for 14 days. After the treatment, the right common carotid artery proximal to the band (RCCA-B) was collected for further assay. Results showed that olmesartan, but not amlodipine, significantly prevented TAC-induced adventitial hyperplasia. Similarly, olmesartan, but not amlodipine, signifcantly prevented vascular infammation, as indicated by increased tumor necrosis factor α (TNF-α) and increased p65 phosphorylation, an indicator of nuclear factor κ-light-chain-enhancer of activated B cells (NFκB) activation in RCCA-B. In contrast, both olmesartan and amlodipine reversed the decreased expression of endothelial nitric oxidase synthase (eNOS) and improved endothelium-dependent vasodilation, whereas combination of olmesartan and amlodipine showed no further synergistic protective effects. These results suggest that AT1R was involved in vascular remodeling and inflammation in response to pressure overload, whereas AT1R and subsequent calcium channel were involved in endothelial dysfunction.

HIF-1α-BNIP3-mediated mitophagy in tubular cells protects against renal ischemia/reperfusion injury.

In the present study, we hypothesized that hypoxia-inducible factor 1α (HIF-1α)-mediated mitophagy plays a protective role in ischemia/reperfusion (I/R)-induced acute kidney injury (AKI). Mitophagy was evaluated by measuring the changes of mitophagy flux, mitochondria DNA copy number, and the changes of mitophagy-related proteins including translocase of outer mitochondrial membrane 20 (TOMM20), cytochrome c oxidase IV (COX IV), microtubule-associated protein 1 light chain 3B (LC3B), and mitochondria adaptor nucleoporin p62 in HK2 cells, a human tubular cell line. Results show that HIF-1α knockout significantly attenuated hypoxia/reoxygenation (H/R)-induced mitophagy, aggravated H/R-induced apoptosis, and increased the production of reactive oxygen species (ROS). Similarly, H/R induced significantly increase in Bcl-2 19-kDa interacting protein 3 (BNIP3), a downstream regulator of HIF-1α. Notably, BNIP3 overexpression reversed the inhibitory effect of HIF-1α knockout on H/R-induced mitophagy, and prevented the enhancing effect of HIF-1α knockout on H/R-induced apoptosis and ROS production. For in vivo study, we established HIF-1αflox/flox; cadherin-16-cre mice in which tubular HIF-1α was specifically knockout. It was found that tubular HIF-1α knockout significantly inhibited I/R-induced mitophagy, and aggravated I/R-induced tubular apoptosis and kidney damage. In contrast, adenovirus-mediated BNIP3 overexpression significantly reversed the decreased mitophagy, and prevented enhanced kidney damage in tubular HIF-1α knockout mice with I/R injury. In summary, our study demonstrated that HIF-1α-BNIP3-mediated mitophagy in tubular cells plays a protective role through inhibition of apoptosis and ROS production in acute kidney damage.

Changes in the composition of the thoracic aortic wall in spontaneously hypertensive rats treated with losartan or spironolactone.

1. In the present study, we compared the elastin and collagen content of thoracic aortic medial and adventitial layers from Wistar-kyoto (WKY) and spontaneously hypertensive rats (SHR). In addition, the effects of losartan, an angiotensin II receptor antagonist, and spironolactone, a mineralocorticoid receptor antagonist, on collagen and elastin content were determined. 2. Prehypertensive (4-week-old) and hypertensive (16-week-old) SHR were randomly divided into three groups treated with either 0.9% NaCl, losartan (20 mg/kg per day) or spironolactone (200 mg/kg per day). Prehypertensive and hypertensive SHR were treated for 12 and 16 weeks, respectively. Age-matched WKY rats were not treated with NaCl, losartan or spironolactone and served as the control group. 3. The medial and adventitial layers of the thoracic aorta were composed mainly of elastin and collagen, respectively, in both SHR and WKY rats. Compared with WKY rats, SHR exhibited greater collagen and elastin content in the media, but decreased collagen and elastin content in the adventitial layer. Both medial and adventitial collagen and elastin content increased significantly with age in both strains and was greater in 32-week-old rats compared with 16-week-old rats. Spironolactone treatment decreased collagen content in the media of thoracic aortas from prehypertensive SHR, whereas losartan decreased collagen content in the media of aortas from hypertensive SHR. In contrast, neither spironolactone nor losartan had any effect on adventitial collagen content in prehypertensive and hypertensive SHR. Medial collagen and elastin were positively related to pulse pressure (PP), but there was no correlation between adventitial mass or collagen content and PP or mean arterial pressure in untreated and treated SHR and WKY rats. 4. In conclusion, the composition of the medial and adventitial layers of the thoracic aorta differs and treatment of SHR with losartan and spironolactone decreases collagen content when delivered at the hypertensive or prehypertensive stage, respectively. However, neither drug has any effect on adventitial collagen content in SHR.

Peroxisome proliferator-activated receptor-gamma agonists attenuate angiotensin II-induced collagen type I expression in adventitial fibroblasts.

1. Angiotensin (Ang) II-mediated oxidative stress may be important in enhanced adventitial fibroblast collagen formation. The aim of the present study was to test whether PPAR-gamma agonists 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ2) and pioglitazone could alter AngII-induced collagen type I formation in vascular adventitial fibroblasts via reactive oxygen species (ROS). 2. Vascular adventitial fibroblasts were isolated from rat thoracic aortas of male Sprague-Dawley rats and treated with different concentrations of AngII for different periods of time. The expression of collagen type I induced by AngII was examined by western blot. Expression of PPAR-gamma mRNA was examined by reverse transcription-polymerase chain reaction (RT-PCR). Intracellular ROS generation was measured by flow cytometry. Activation of transcription factors nuclear factor (NF)-kappaB and activator protein (AP)-1 was assessed by an electrophoretic mobility shift assay. 3. Angiotensin II increased expression of collagen type I in a time- and dose-dependent manner in adventitial fibroblasts. In addition, AngII stimulated intracellular generation of ROS in adventitial fibroblasts. Pretreatment of cells with 15d-PGJ2 and pioglitazone attenuated collagen type I expression and generation of ROS induced by AngII, respectively. Moreover, we observed that N-acetylcysteine inhibited collagen type I expression induced by AngII as did the PPAR-gamma agonists. Angiotensin II treatment activated the redox-sensitive transcription factors NF-kappaB and AP-1, whereas pretreatment with 15d-PGJ2 and pioglitazone reduced the AngII-induced DNA-binding activity of NF-kappaB but not AP-1. 4 Our data demonstrate that the PPAR-gamma agonists 15d-PGJ2 and pioglitazone attenuate AngII-mediated collagen type I expression in adventitial fibroblasts, which may be mediated by the modulation of ROS release and the redox-sensitive transcription factor NF-kappaB.

Treatment of bactericide wastewater by combined process chemical coagulation, electrochemical oxidation and membrane bioreactor.

Bactericide wastewater (BIW) contains isothiazolin-ones, high salinity, toxicity and non-biodegradable organic concentrations. In order to enhance biodegradable capacity, chemical coagulation and electrochemical oxidation were applied to pretreatment processes. FeSO(4).7H2O, pH 12 and 20 mmol/l were determined as optimal chemical coagulation condition; and 15 mA/cm2 of current density, 10 ml/min of flow rate and pH 7 were chosen for the most efficient electrochemical oxidation condition at combined treatment. The wastewater which consisted mainly of isothiazolin-ones and sulfide was efficiently treated by chemical coagulation and electrochemical oxidation. The optimal pretreatment processes showed 60.9% of chemical oxygen demand (COD), 99.5% of S(2-) and 96.0% of isothiazolin-ones removal efficiency. A biological treatment system using membrane bioreactor (MBR) adding powder-activated carbon (PAC) was also investigated. COD of the wastewater which was disposed using a MBR was lower than 100 mg/l.

[Differential expression of microRNAs in the aorta of spontaneously hypertensive rats].

MicroRNAs (miRNAs) are genomically encoded non-protein-encoding small RNAs, which negatively regulate target gene expression at post-transcriptional level. The present study aimed to investigate whether disorders of miRNAs system were involved in the pathogenesis of hypertension in spontaneously hypertensive rats (SHR). MiRanda, Target Scan and PicTar were utilized for predictive analysis of miRNAs and target genes. MiR-1, miR-133a, miR-155 and miR-208 were selected as the candidate miRNAs potentially related to blood pressure. The expression levels of miR-1, miR-133a, miR-155 and miR-208 in the aorta of 4-, 8-, 16- and 24-week-old SHR and age-matched Wistar-Kyoto (WKY) rats were detected by real-time RT-PCR. The mRNA levels of angiotensin II receptor type 1 (AGTR1a), angiotensin II receptor associated protein (AGTRAP), divalent metal transporter 1 (DMT1), low-density lipoprotein-related protein 1B (LRP1B), fibroblast growth factor-7 (FGF-7), protocadherin 9 precursor (PCDH9), chloride channel protein 5 (CLCN-5), small conductance calcium activated potassium channel protein 3 (KCNN3) and thyroid hormone receptor associated protein 1 (THRAP1), which were predicted to be target genes of differentially expressed miRNAs, were further detected by real-time RT-PCR. The results obtained showed that the expression levels of miR-1, miR-155 and miR-208 in the aorta were significantly different from those in the heart of WKY rats. The miR-155 level was significantly lower in aorta of 16-week-old SHR than that of age-matched WKY rats (P<0.05), but there was no difference between SHR and WKY rats in other age groups. In addition, miR-155 level was negatively correlated to blood pressure (r=-0.525, P<0.05). Both in WKY rats and SHR, miR-208 was most abundantly expressed in 4-week-old rats, but declined significantly in 8-, 16- and 24-week-old rats (P<0.05). No difference in miR-208 levels was observed between age-matched SHR and WKY rats. Moreover, miR-208 expression in aorta was negatively correlated with blood pressure (r=-0.400, P<0.05) and age (r=-0.684, P<0.0001). Neither miR-1 nor miR-133a was differentially expressed in SHR and WKY rats in different age groups. The mRNA levels of predicted target genes were not correlated to miR-155 or miR-208 levels. These results indicate that miR-155 is less expressed in the aorta of adult SHR compared with that of WKY rats and is negatively correlated with blood pressure, suggesting it is possibly involved in the development and pathologic progress of hypertension. The miR-208 expression in rat aorta declines with aging and it may play a role in the blood vessel development.