The homeostasis of metal ions, such as iron, copper, zinc and calcium, in the brain is crucial for maintaining normal physiological functions. Studies have shown that imbalance of these metal ions in ...the brain is closely related to the onset and progression of Alzheimer's disease (AD), the most common neurodegenerative disorder in the elderly.
Erroneous deposition/distribution of the metal ions in different brain regions induces oxidative stress. The metal ions imbalance and oxidative stress together or independently promote amyloid-β (Aβ) overproduction by activating β- or γ-secretases and inhibiting α-secretase, it also causes tau hyperphosphorylation by activating protein kinases, such as glycogen synthase kinase-3β (GSK-3β), cyclin-dependent protein kinase-5 (CDK5), mitogen-activated protein kinases (MAPKs), etc., and inhibiting protein phosphatase 2A (PP2A). The metal ions imbalances can also directly or indirectly disrupt organelles, causing endoplasmic reticulum (ER) stress; mitochondrial and autophagic dysfunctions, which can cause or aggravate Aβ and tau aggregation/accumulation, and impair synaptic functions. Even worse, the metal ions imbalance-induced alterations can reversely exacerbate metal ions misdistribution and deposition. The vicious cycles between metal ions imbalances and Aβ/tau abnormalities will eventually lead to a chronic neurodegeneration and cognitive deficits, such as seen in AD patients.
The metal ions imbalance induces Aβ and tau pathologies by directly or indirectly affecting multiple cellular/subcellular pathways, and the disrupted homeostasis can reversely aggravate the abnormalities of metal ions transportation/deposition. Therefore, adjusting metal balance by supplementing or chelating the metal ions may be potential in ameliorating AD pathologies, which provides new research directions for AD treatment.
Background
Pulmonary arterial hypertension (PAH) is characterized by the apoptosis resistance and hyperproliferation of pulmonary artery smooth muscle cells (PASMCs). Its pathogenesis has not been ...revealed. Here, we carried out experiments to investigate the functions of miR‐140‐5p and tumor necrosis factor‐α (TNF‐α).
Methods
We selected GSE703 from Gene Expression Omnibus (GEO) Database to conduct microarray analysis using R software and Gene Set Enrichment Analysis (GSEA). Combing bioinformatics results, the upregulation of miR‐140‐5p inhibited PAH progression through targeting TNF‐α. RNA expression was measured by quantitative real‐time polymerase chain reaction (RT‐qPCR) and protein level was measured by western blot analysis and enzyme‐linked immunosorbent assays (ELISA). We conducted monocrotaline (MCT) injection to rats to form PAH animal models. The lung tissues were observed by hematoxylin–eosin (HE) staining and Sirius red‐picric acid staining. Right ventricular systolic pressure (RVSP) and the ratio of right ventricle (RV)‐to‐left ventricle (LV) plus septum (S) weight (RV/LV + S) were measured in MCT‐induced animal models. Overexpression of miR‐140‐5p and TNF‐α were utilized to research the proliferation, migration, and phenotypic variation of hypoxia‐mediated PASMCs. The binding between miR‐140‐5p and TNF‐α 3′‐untranslated region (3′‐UTR) was confirmed via luciferase reporter assay.
Results
Downregulation of miR‐140‐5p and upregulation of TNF‐α were observed in PAH rat model and hypoxia‐mediated PASMCs. And we proved that overexpression of miR‐140‐5p could suppress the proliferation, migration, and phenotypic variation of PASMCs, therefore inhibiting PAH pathogenesis. Luciferase assay verified that miR‐140‐5p targeted TNF‐α directly. A converse correlation was also shown between miR‐140‐5p and TNF‐α in PASMCs.
Conclusions
miR‐140‐5p and TNF‐α are important regulators in PAH pathology and may serve as a therapeutic target for PAH.
miR‐140‐5p might inhibit the occurrence and development of pulmonary arterial hypertension (PAH) by repressing tumor necrosis factor‐α (TNF‐α) expression via the TNF signaling pathway. These findings may help in the search of promising strategies for achieving better treatment outcome in patients diagnosed with PAH.
BACKGROUND:GTP cyclohydrolase 1 (GCH1) deficiency is critical for endothelial nitric oxide synthase uncoupling in endothelial dysfunction. MicroRNAs (miRs) are a class of regulatory RNAs that ...negatively regulate gene expression. We investigated whether statins prevent endothelial dysfunction via miR-dependent GCH1 upregulation.
METHODS:Endothelial function was assessed by measuring acetylcholine-induced vasorelaxation in the organ chamber. MiR-133a expression was assessed by quantitative reverse transcription polymerase chain reaction and fluorescence in situ hybridization.
RESULTS:We first demonstrated that GCH1 mRNA is a target of miR-133a. In endothelial cells, miR-133a was robustly induced by cytokines/oxidants and inhibited by lovastatin. Furthermore, lovastatin upregulated GCH1 and tetrahydrobiopterin, and recoupled endothelial nitric oxide synthase in stressed endothelial cells. These actions of lovastatin were abolished by enforced miR-133a expression and were mirrored by a miR-133a antagomir. In mice, hyperlipidemia- or hyperglycemia-induced ectopic miR-133a expression in the vascular endothelium, reduced GCH1 protein and tetrahydrobiopterin levels, and impaired endothelial function, which were reversed by lovastatin or miR-133a antagomir. These beneficial effects of lovastatin in mice were abrogated by in vivo miR-133a overexpression or GCH1 knockdown. In rats, multiple cardiovascular risk factors including hyperglycemia, dyslipidemia, and hyperhomocysteinemia resulted in increased miR-133a vascular expression, reduced GCH1 expression, uncoupled endothelial nitric oxide synthase function, and induced endothelial dysfunction, which were prevented by lovastatin.
CONCLUSIONS:Statin inhibits aberrant miR-133a expression in the vascular endothelium to prevent endothelial dysfunction by targeting GCH1. Therefore, miR-133a represents an important therapeutic target for preventing cardiovascular diseases.
Our study explored the effects of lncRNA UCA1 on the proliferation and apoptosis in hypoxic human pulmonary artery smooth muscle cells (HPASMCs) and highlighted the endogenous relationship between ...UCA1, ING5, and hnRNP I in cell proliferation. Hypoxia-induced HPASMCs were used to simulate pulmonary arterial hypertension in vitro. Microarray assay was adopted to screen the dysregulated expressed lncRNAs in HPASMCs to find out the target gene of our study. And RT-qPCR was performed to detect the expression of lncRNA UCA1 under hypoxia and normoxia. After transfection, the relationship between UCA1 and cell proliferation in HPASMCs under hypoxia were determined by cell proliferation assay and relative expression of PCNA. Next, ELISA assays were conducted to measure the protein levels of PCNA and ING5. What’s more, flow cytometry was employed to measure the apoptosis rate in differentially UCA1-expressed HPASMCs. RIP assays were conducted to further clarify the endogenous relationship between UCA1 and ING5 in hypoxic HPASMCs. Finally, the effects of ING5 to HPASMCs were detected after transfection of ING5 and UCA1 to figure out the role of ING5 in HPASMCs. Hypoxia was revealed to induce proliferation and inhibited apoptosis in HPASMCs. Besides, UCA1 was confirmed to be highly expressed under hypoxia compared with normoxia. UCA1 boosted cell proliferation under hypoxia in HPASMCs. However, the apoptosis was suppressed in the hypoxic HPASMCs transfected with pcDNA3.1-UCA1. Further, mechanism studies found that UCA1 competed with ING5 for hnRNP I, so that upregulating UCA1 inhibited the protein levels of ING5. And finally we found that ING5 restrained cell viability, but promoted cell apoptosis in hypoxic HPASMCs, which was reversed by UCA1 over-expression. In summary, our findings manifested that UCA1 promoted proliferation and restrained apoptosis by competing with ING5 for hnRNP I in HPASMCs induced by hypoxia, indicating their potential roles for the cure of hypoxic pulmonary hypertension.
To explore whether rosiglitazone (RSG), a selective peroxisome proliferator‐activated receptor γ (PPARγ) agonist, exerts beneficial effects on endothelial dysfunction induced by homocysteine ...thiolactone (HTL) and to investigate the potential mechanisms. Incubation of cultured human umbilical vein endothelial cells with HTL (1 mM) for 24 hrs significantly reduced cell viabilities assayed by 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide, as well as enhanced productions of reactive oxygen species, activation of nuclear factor kappa B, and increased intercellular cell adhesion molecule‐1 secretion. Pre‐treatment of cells with RSG (0.001–0.1 mM), pyrollidine dithiocarbamate (PDTC, 0.1 mM) or apocynin (0.1 mM) for 1 hr reversed these effects induced by HTL. Furthermore, co‐incubation with GW9662 (0.01 mM) abolished the protective effects of RSG on HTL‐treated cells. In ex vivo experiments, exposure of isolated aortic rings from. rats to HTL (1 mM) for 1 hr dramatically impaired acetylcholine‐induced endothelium‐dependent relaxation, reduced release of nitric oxide and activity of superoxide dismutase, and increased malondialdehyde content in aortic tissues. Preincubation of aortic rings with RSG (0.1, 0.3, 1 mM), PDTC or apocynin normalized the disorders induced by HTL. In vivo analysis indicated that administration of RSG (20 mg/kg/d) remarkably suppressed oxidative stress and prevented endothelial dysfunction in rats fed HTL (50 mg/kg/d) for 8 weeks. RSG improves endothelial functions in rats fed HTL, which is related to PPARγ‐dependent suppression of oxidative stress.
Ultrasound‐mediated microbubble cavitation (UMMC) induces therapeutic angiogenesis to treat ischemic diseases. This study aimed to investigate whether diagnostic UMMC alleviates diabetic ...cardiomyopathy (DCM) and, if so, through which mechanisms. DCM model was established by injecting streptozocin into rats to induce hyperglycemia, followed by a high‐fat diet. The combined therapy of cation microbubble with low‐intensity diagnostic ultrasound (frequency = 4 MHz), with a pulse frequency of 20 Hz and pulse length (PL) of 8, 18, 26, or 36 cycles, was given to rats twice a week for 8 consecutive weeks. Diagnostic UMMC therapy with PL at 8, 18, and 26 cycles, but not 36 cycles, dramatically prevented myocardial fibrosis, improved heart functions, and increased angiogenesis, accompanied by increased levels of PI3K, Akt, and eNOS proteins in the DCM model of rats. In cultured endothelial cells, low‐intensity UMMC treatment (PL = 3 cycles, sound pressure level = 50%, mechanical index = 0.82) increased cell viability and activated PI3K‐Akt‐eNOS signaling. The combination of diagnostic ultrasound with microbubble destruction dose‐dependently promoted angiogenesis, thus improving heart function through PI3K‐Akt‐eNOS signaling in diabetes. Accordingly, diagnostic UMMC therapy should be considered to protect the heart in patients with diabetes.
The medical usage of Doxorubicin (DOX) as a chemotherapeutic agent is restricted owing to its cardiotoxic properties. This study was designed to explore the effect and underlying mechanisms of ...Citronellal (CT) on DOX‐related cardiotoxicity in rats. Rats were divided into six groups: control, DOX, CT, Lithium chloride (LiCl) (a Na+/H+exchanger‐1 NHE1 activator), DOX + CT, and DOX + CT + LiCl. To induce cardiotoxicity, a cumulative dose of 15 mg/kg DOX was intraperitoneally injected into rats. CT (150 mg/kg) and LiCl (1 mg/kg) were given daily by oral gavage for 6 weeks. CT improved cardiac functional parameters and attenuated the cardiac pathological changes induced by DOX. Further study indicated that CT administration regulated the levels of oxidative stress and apoptosis‐related factors and in myocardial tissues, reducing cell per‐oxidative damage and apoptosis. Besides this, CT attenuated DOX‐induced NHE1 upregulation, and the preventive effects of CT against DOX‐induced cardiotoxicity were abrogated by the concurrent administration of LiCl. These results demonstrate that CT could ameliorate DOX‐induced cardiotoxicity by inhibiting the NHE1‐mediated oxidative stress, apoptosis in rats.
Endothelial cells form the innermost layer of blood vessels with a fundamental role as the physical barrier. While regulation of endothelial cell function by reactive oxygen species (ROS) is critical ...in physiological processes such as angiogenesis, endothelial function is a major target for interruption by oxidative stress resulting from generation of high levels of ROS in endothelial cells by various pathological factors and also release of ROS by neutrophils. TRPM2 is a ROS-sensitive Ca2+-permeable channel expressed in endothelial cells of various vascular beds. In this review, we provide an overview of the TRPM2 channel and its role in mediating ROS-induced Ca2+ signaling in endothelial cells. We discuss the TRPM2-mediated Ca2+ signaling in vascular endothelial growth factor-induced angiogenesis and in post-ischemic neovascularization. In particular, we examine the accumulative evidence that supports the role of TRPM2-mediated Ca2+ signaling in endothelial cell dysfunction caused by various oxidative stress-inducing factors that are associated with tissue inflammation, obesity and diabetes, as well as air pollution. These findings provide new, mechanistic insights into ROS-mediated regulation of endothelial cells in physiology and diseases.
s: Hyperhomocysteinemia (HHcy) is one of risk factors for vascular cognitive impairment (VCI). GTP cyclohydrolase 1 (GCH1) deficiency is critical to oxidative stress in vascular dysfunction. The aim ...of this study was designed to examine whether HHcy induces VCI through GCH1 S-nitrosylation, a redox-related post-translational modification of cysteine.
The VCI model was induced by feeding mice homocysteine thiolactone (HTL) for 16 consecutive weeks. The cognitive functions were evaluated by step-down avoidance test, passive avoidance step-through task test, and Morris water maze (MWM) test. Protein S-nitrosylation was assayed using a biotin-switch method.
In cell-free system, nitric oxide (NO) donor induced GCH1 protein S-nitrosylation and decreased GCH1 activity. In endothelial cells, HTL increased GCH1 S-nitrosylation, reduced tetrahydrobiopterin, and induced oxidative stress, which were attenuated by N-acetyl-cysteine, L-N6-1-Iminoethyl-lysine, mutant of GCH1 cysteine 141 to alanine (MT-GCH1) or gene deletion of inducible NO synthase (iNOS). Further, HTL incubation or iNOS overexpression promoted endothelial cellular senescence, but abolished by exogenous expression of MT-GCH1 or pharmacological approaches including N-acetyl-cysteine, L-sepiapterin, and tempol. In wildtype mice, long-term administration of HTL induced GCH1 S-nitrosylation and vascular stiffness, decreased cerebral blood flow, and damaged the cognitive functions. However, these abnormalities induced by HTL administration were rescued by enforced expression of MT-GCH1 or gene knockout of iNOS. In human subjects, GCH1 S-nitrosylation was increased and cognitive functions were impaired in patients with HHcy.
The iNOS-mediated nitrosative stress induced by HTL drives GCH1 S-nitrosylation to induce cerebral vascular stiffness and cognitive impairments.
Diabetic cardiomyopathy (DCM), a cardiovascular complication of patients with diabetes, is a special cardiomyopathy that is independent of coronary heart disease, hypertension, and valvular disease. ...Citronellal (CT) is a monoterpene compound generated by the secondary metabolism of plants. In this work, the therapeutic effect and mechanism of CT in DCM were investigated. Experimental diabetic rat models were constructed through a high-fat and high-carbohydrate diet combined with low-dosage streptozotocin (STZ) treatment. CT was intragastrically administered at the dosage of 150 mg/kg/day. The cardiac functions of the rats were evaluated via cardiac Doppler ultrasound. Changes in myocardial structure were analyzed through histopathology. Changes in the representative indices of oxidative stress, namely, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were detected on the basis of a biochemical test. Related protein levels were assayed via immunofluorescence and Western blot analyses. The DCM rats in the nontreatment group experienced diastolic and systolic dysfunctions, associated with myocardial hypertrophy, fibrosis, and cardiomyocyte apoptosis. Moreover, this condition was concurrent with metabolic disorders, the degradation of SOD activity in myocardial tissues, the increase in MDA content, the abnormal activation of sodium–hydrogen exchanger 1 (NHE1), and the aggravation of cell apoptosis (Bax levels were elevated, whereas Bcl-2 levels decreased). Myocardial hypertrophy, fibrosis, oxidative stress, and cell apoptosis were obviously inhibited after treatment with CT (150 mg/kg/day). The abnormal activation of NHE1 was recovered under the action of CT. Our study results showed that CT might play a protective role in the treatment of DCM by repressing the abnormal activation of NHE1.
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