Emerging perspectives on cytoglobin, beyond NO dioxygenase and peroxidase.

Cytoglobin is an evolutionary ancient hemoglobin with poor functional annotation. Rather than constrained to penta coordination, cytoglobin's heme iron may exist either as a penta or hexacoordinated arrangement when exposed to different intracellular environments. Two cysteine residues at the surface of the protein form an intramolecular disulfide bond that regulates iron coordination, ligand binding, and peroxidase activity.

Thymine DNA glycosylase is a key regulator of CaMKIIγ expression and vascular smooth muscle phenotype.

Multifunctional Ca/calmodulin-dependent protein kinase II (CaMKII) is a multigene family with isoform-specific regulation of vascular smooth muscle (VSM) functions. In previous studies, we found that vascular injury resulted in VSM dedifferentiation and reduced expression of the CaMKIIγ isoform in medial wall VSM. Smooth muscle knockout of CaMKIIγ enhanced injury-induced VSM neointimal hyperplasia, whereas CaMKIIγ overexpression inhibited VSM proliferation and neointimal formation.

Vimentin expression is required for the development of EMT-related renal fibrosis following unilateral ureteral obstruction in mice.

Most renal transplants ultimately fail secondary to chronic allograft nephropathy (CAN). Vimentin (vim) is a member of the intermediate filament family of proteins and has been shown to be important in the development of CAN. One of the pathways leading to chronic renal fibrosis after transplant is thought to be epithelial to mesenchymal transition (EMT).

Cytoglobin Promotes Cardiac Progenitor Cell Survival against Oxidative Stress via the Upregulation of the NFκB/iNOS Signal Pathway and Nitric Oxide Production.

Human cardiac stem/progenitor cells (hCPCs) may serve in regenerative medicine to repair the infarcted heart. However, this approach is severely limited by the poor survival of donor cells. Recent studies suggest that the mammalian globin cytoglobin (CYGB) regulates nitric oxide (NO) metabolism and cell death.

The Hemoglobin Homolog Cytoglobin in Smooth Muscle Inhibits Apoptosis and Regulates Vascular Remodeling.

Objective: The role of hemoglobin and myoglobin in the cardiovascular system is well established, yet other globins in this context are poorly characterized. Here, we examined the expression and function of cytoglobin (CYGB) during vascular injury.

Approach And Results: We characterized CYGB content in intact vessels and primary vascular smooth muscle (VSM) cells and used 2 different vascular injury models to examine the functional significance of CYGB in vivo.

Dual Function for Mature Vascular Smooth Muscle Cells During Arteriovenous Fistula Remodeling.

Background: The arteriovenous fistula (AVF) is the preferred form of hemodialysis access for patients with chronic kidney disease. However, AVFs are associated with significant problems including high incidence of both early and late failures, usually attributed to inadequate venous arterialization and neointimal hyperplasia, respectively. Understanding the cellular basis of venous remodeling in the setting of AVF could provide targets for improving AVF patency rates.

Xanthine oxidase-mediated denitrosation of N-nitroso-tryptophan by superoxide and uric acid.

Recent studies indicate the formation of protein nitrosamines in vivo and tryptophan residues in proteins might represent important targets of nitrosative and oxidative stress. In the present work, we examined the mechanism by which xanthine oxidase (XO) denitrosates N-nitroso Trp residues and determined the applicability of the reactions involved to the detection of nitrosated Trp residues by tri-iodide-based chemiluminescence. We found that - in addition to superoxide - denitrosation of N-acetyl-nitroso Trp (NANT) by hypoxanthine and XO occurred via the intermediacy of uric acid.

NADPH oxidase 4 is required for interleukin-1β-mediated activation of protein kinase Cδ and downstream activation of c-jun N-terminal kinase signaling in smooth muscle.

Reactive oxygen species (ROS) are generated in the vascular wall upon stimulation by proinflammatory cytokines and are important mediators of diverse cellular responses that occur as a result of vascular injury. Members of the NADPH oxidase (NOX) family of proteins have been identified in vascular smooth muscle (VSM) cells as important sources of ROS. In this study, we tested the hypothesis that NOX4 is a proximal mediator of IL-1β-dependent activation of PKCδ and increases IL-1β-stimulated c-Jun kinase (JNK) signaling in primary rat aortic VSM cells.

Cytoglobin is expressed in the vasculature and regulates cell respiration and proliferation via nitric oxide dioxygenation.

Disposition of the second messenger nitric oxide (NO) in mammalian tissues occurs through multiple pathways including dioxygenation by erythrocyte hemoglobin and red muscle myoglobin. Metabolism by a putative NO dioxygenase activity in non-striated tissues has also been postulated, but the exact nature of this activity is unknown. In the present study, we tested the hypothesis that cytoglobin, a newly discovered hexacoordinated globin, participates in cell-mediated NO consumption.

Redox control of G(1)/S cell cycle regulators during nitric oxide-mediated cell cycle arrest.

Redox regulation of cell cycle progression during nitric oxide (NO) mediated cytostasis is not well-understood. In this study, we investigated the role of the intracellular antioxidant glutathione (GSH) in regulating specific signaling events that are associated with NO-mediated cell cycle arrest. Manipulation of intracellular GSH content through pharmacological inhibition of glutamate-cysteine ligase (GCL) indicated that GSH depletion potentiated nitrosative stress, DNA damage, phosphorylation of the tumor suppressor p53 (Ser-18) and upregulation of p21(cip1/waf1) upon NO stimulation.

Detection of nitrosothiols and other nitroso species in vitro and in cells.

The nitric oxide (NO)-mediated nitrosation of peptides and proteins may play important roles in normobiology and pathobiology. With the realization that S-nitrosothiols (RSNOs) participate in the transport, storage, and delivery of NO, as well as posttranslational modifications in cell signaling and inflammatory processes, there is an increasing need for the detection of nitrosothiols (RSNOs) and other nitroso species in cells and tissues. In this chapter, we describe the utilization of a gas phase chemiluminescence-based assay and "biotin switch" method for the detection of nitroso species in cells.

Oxidation and nitrosation of thiols at low micromolar exposure to nitric oxide. Evidence for a free radical mechanism.

Although the nitric oxide (.NO)-mediated nitrosation of thiol-containing molecules is increasingly recognized as an important post-translational modification in cell signaling and pathology, little is known about the factors that govern this process in vivo. In the present study, we examined the chemical pathways of nitrosothiol (RSNO) production at low micromolar concentrations of .