The protein S-nitrosylation of splicing and translational machinery in vascular endothelial cells is susceptible to oxidative stress induced by oxidized low-density lipoprotein

Roles of Protein S-Nitrosylation in Endothelial Homeostasis and Dysfunction

Significance: Nitric oxide (NO) plays several distinct roles in endothelial homeostasis. Except for activating the guanylyl cyclase enzyme-dependent cyclic guanosine monophosphate signaling pathway, NO can bind reactive cysteine residues in target proteins, a process known as S-nitrosylation (SNO). SNO is proposed to explain the multiple biological functions of NO in the endothelium. Investigating the targets and mechanism of protein SNO in endothelial cells (ECs) can provide new strategies for treating endothelial dysfunction-related diseases. Recent Advances: In response to different environments, proteomics has identified multiple SNO targets in ECs. Functional studies confirm that SNO regulates NO bioavailability, inflammation, permeability, oxidative stress, mitochondrial function, and insulin sensitivity in ECs. It also influences EC proliferation, migration, apoptosis, and transdifferentiation. Critical Issues: Single-cell transcriptomic analysis of ECs isolated from different mouse tissues showed heterogeneous gene signatures. However, litter research focuses on the heterogeneous properties of SNO proteins in ECs derived from different tissues. Although metabolism reprogramming plays a vital role in endothelial functions, little is known about how protein SNO regulates metabolism reprogramming in ECs. Future Directions: Precisely deciphering the effects of protein SNO in ECs isolated from different tissues under different conditions is necessary to further characterize the relationship between protein SNO and endothelial dysfunction-related diseases. In addition, identifying SNO targets that can influence endothelial metabolic reprogramming and the underlying mechanism can offer new views on the crosstalk between metabolism and post-translational protein modification. Antioxid. Redox Signal. 40, 186-205.

When nitrosative stress hits the endoplasmic reticulum: Possible implications in oxLDL/oxysterols-induced endothelial dysfunction

Oxidized LDL (oxLDL) and oxysterols are known to play a crucial role in endothelial dysfunction (ED) by inducing endoplasmic reticulum stress (ERS), inflammation, and apoptosis. However, the precise molecular mechanisms underlying these pathophysiological processes remain incompletely understood. Emerging evidence strongly implicates excessive nitric oxide (NO) production in the progression of various pathological conditions. The accumulation of reactive nitrogen species (RNS) leading to nitrosative stress (NSS) and aberrant protein S-nitrosylation contribute to NO toxicity. Studies have highlighted the involvement of NSS and S-nitrosylation in perturbing ER signaling through the modification of ER sensors and resident isomerases in neurons. This review focuses on the existing evidence that strongly associates NO with ERS and the possible implications in the context of ED induced by oxLDL and oxysterols. The potential effects of perturbed NO synthesis on signaling effectors linking NSS with ERS in endothelial cells are discussed to provide a conceptual framework for further investigations and the development of novel therapeutic strategies targeting ED.

Hsp90 S-nitrosylation at Cys521, as a conformational switch, modulates cycling of Hsp90-AHA1-CDC37 chaperone machine to aggravate atherosclerosis

Endothelial dysfunction is the initial process of atherosclerosis. Heat shock protein 90 (Hsp90), as a molecular chaperone, plays a crucial role in various cardiovascular diseases. Hsp90 function is regulated by S-nitrosylation (SNO). However, the precise role of SNO-Hsp90 in endothelial dysfunction during atherosclerosis remains unclear. We here identified Hsp90 as a highly S-nitrosylated target in endothelial cells (ECs) by biotin switch assay combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The elevation of SNO-Hsp90 was observed in atherosclerotic human and rodent aortas as well as in oxidized LDL (oxLDL)-treated ECs. Inhibition of inducible nitric oxide synthase (iNOS) or transfection with Hsp90 cysteine 521 (Cys521) mutation plasmid decreased the level of SNO-Hsp90 in oxLDL-cultured ECs. Coimmunoprecipitation and proximity ligation assay demonstrated that SNO-Hsp90 at Cys521 suppressed the interaction between Hsp90 and activator of Hsp90 ATPase activity 1 (AHA1), but promoted the association of Hsp90 and cell division cycle 37 (CDC37). Hsp90 Cys521 mutation increased endothelial nitric oxide synthase (eNOS) activity and inhibited nuclear factor kappa-B (NF-κB) signaling, thereby increasing nitric oxide (NO) bioavailability and alleviating endothelial adhesion, inflammation and oxidative stress in oxLDL-treated ECs. Also, administration of endothelial-specific adeno-associated viruses of Cys521-mutated Hsp90 significantly mitigated vascular oxidative stress, macrophage infiltration and atherosclerosis lesion areas in high fat diet-fed ApoE^-/- mice. In conclusion, SNO-Hsp90 at Cys521, that serves as a conformational switch, disrupts Hsp90/AHA1 interaction but promotes recruitment of CDC37 to exacerbate atherosclerosis.

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Hsp90 S-nitrosylation at Cys521 acts as a conformational switch to modulate Hsp90/AHA1 and Hsp90/CDC37 interaction.

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SNO-Hsp90 induces endothelial adhesion, inflammation and oxidative stress.

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SNO-Hsp90 mediates endothelial dysfunction to exacerbate atherosclerosis.

A Commonly Used Biocide 2-N-octyl-4-isothiazolin-3-oneInduces Blood-Brain Barrier Dysfunction via Cellular Thiol Modification and Mitochondrial Damage

Isothiazolinone (IT) biocides are potent antibacterial substances commonly used as preservatives or disinfectants, and 2-n-Octyl-4-isothiazolin-3-one (OIT; octhilinone) is a common IT biocide that is present in leather products, glue, paints, and cleaning products. Although humans are exposed to OIT through personal and industrial use, the potentially deleterious effects of OIT on human health are still unknown. To investigate the effects of OIT on the vascular system, which is continuously exposed to xenobiotics through systemic circulation, we treated brain endothelial cells with OIT. OIT treatment significantly activated caspase-3-mediated apoptosis and reduced the bioenergetic function of mitochondria in a bEnd.3 cell-based in vitro blood–brain barrier (BBB) model. Interestingly, OIT significantly altered the thiol redox status, as evidenced by reduced glutathione levels and protein S-nitrosylation. The endothelial barrier function of bEnd.3 cells was significantly impaired by OIT treatment. OIT affected mitochondrial dynamics through mitophagy and altered mitochondrial morphology in bEnd.3 cells. N-acetyl cysteine significantly reversed the effects of OIT on the metabolic capacity and endothelial function of bEnd.3 cells. Taken together, we demonstrated that the alteration of the thiol redox status and mitochondrial damage contributed to OIT-induced BBB dysfunction, and we hope that our findings will improve our understanding of the potential hazardous health effects of IT biocides.

Endothelial dysfunction in neuroprogressive disorders-causes and suggested treatments

BACKGROUND

Potential routes whereby systemic inflammation, oxidative stress and mitochondrial dysfunction may drive the development of endothelial dysfunction and atherosclerosis, even in an environment of low cholesterol, are examined.

MAIN TEXT

Key molecular players involved in the regulation of endothelial cell function are described, including PECAM-1, VE-cadherin, VEGFRs, SFK, Rho GEF TRIO, RAC-1, ITAM, SHP-2, MAPK/ERK, STAT-3, NF-κB, PI3K/AKT, eNOS, nitric oxide, miRNAs, KLF-4 and KLF-2. The key roles of platelet activation, xanthene oxidase and myeloperoxidase in the genesis of endothelial cell dysfunction and activation are detailed. The following roles of circulating reactive oxygen species (ROS), reactive nitrogen species and pro-inflammatory cytokines in the development of endothelial cell dysfunction are then described: paracrine signalling by circulating hydrogen peroxide, inhibition of eNOS and increased levels of mitochondrial ROS, including compromised mitochondrial dynamics, loss of calcium ion homeostasis and inactivation of SIRT-1-mediated signalling pathways. Next, loss of cellular redox homeostasis is considered, including further aspects of the roles of hydrogen peroxide signalling, the pathological consequences of elevated NF-κB, compromised S-nitrosylation and the development of hypernitrosylation and increased transcription of atherogenic miRNAs. These molecular aspects are then applied to neuroprogressive disorders by considering the following potential generators of endothelial dysfunction and activation in major depressive disorder, bipolar disorder and schizophrenia: NF-κB; platelet activation; atherogenic miRs; myeloperoxidase; xanthene oxidase and uric acid; and inflammation, oxidative stress, nitrosative stress and mitochondrial dysfunction.

CONCLUSIONS

Finally, on the basis of the above molecular mechanisms, details are given of potential treatment options for mitigating endothelial cell dysfunction and activation in neuroprogressive disorders.

Identification of Cytosolic Protein Targets of Catechol Estrogens in Breast Cancer Cells Using a Click Chemistry-Based Workflow

Catechol estrogens (CEs) are known to be toxic metabolites and the initiators of the oncogenesis of breast cancers via forming covalent adducts with DNAs. CEs shall also react with proteins, but their cellular protein targets remain unexplored. Here, we reported the identification of protein targets of CEs in the soluble cytosol of estrogen-sensitive breast cancer cells by multiple comparative proteomics using liquid chromatography-tandem mass spectrometry (LC-MS/MS) coupled with an improved click chemistry-based workflow. Multiple comparative proteomics composed of an experimental pair (probe versus solvent) and two control pairs (solvent versus solvent and probe versus solvent without enrichment) were studied using stable isotope dimethyl labeling. The use of 4-hydroxyethynylestradiol (4OHEE2) probe with an amide-free linker coupled with on-bead digestion and redigestion of the proteins cleaved from the beads was shown to greatly improve the recovery and identification of CE-adducted peptides. A total of 310 protein targets and 40 adduction sites were repeatedly (n ≥ 2) identified with D/H (probe/solvent) ratio >4 versus only one identified with D/H >4 from the two control pairs, suggesting that our workflow imposes only a very low background. Meanwhile, multiple comparative D/H ratios revealed that CEs may downregulate many target proteins involved in the metabolism or detoxification, suggesting a negative correlation between CE-induced adduction and expression of proteins acting on the alleviation of stress-induced cellular damages. The reported method and data will provide opportunities to study the progression of estrogen metabolism-derived diseases and biomarkers.

S-nitrosylation and its role in breast cancer angiogenesis and metastasis

S-nitrosylation, the modification by nitric oxide of free sulfhydryl groups in cysteines, has become an important regulatory mechanism in carcinogenesis and metastasis. S-nitrosylation of targets in tumor cells contributes to metastasis regulating epithelial to mesenchymal transition, migration and invasion. In the tumor environment, the role of S-nitrosylation in endothelium has not been addressed; however, the evidence points out that S-nitrosylation of endothelial proteins may regulate angiogenesis, adhesion of tumor cells to the endothelium, intra and extravasation of tumor cells and contribute to metastasis.