NOX4 (NADPH Oxidase 4) and Poldip2 (Polymerase δ-Interacting Protein 2) Induce Filamentous Actin Oxidation and Promote Its Interaction With Vinculin During Integrin-Mediated Cell Adhesion.

Objective- Actin cytoskeleton assembly and organization, as a result of focal adhesion (FA) formation during cell adhesion, are dependent on reactive oxygen species and the cellular redox environment. Poldip2 (polymerase δ-interacting protein 2), a novel regulator of NOX4 (NADPH oxidase 4), plays a significant role in reactive oxygen species production and cytoskeletal remodeling. Thus, we hypothesized that endogenous reactive oxygen species derived from Poldip2/NOX4 contribute to redox regulation of actin and cytoskeleton assembly during integrin-mediated cell adhesion.

Poldip2 knockdown inhibits vascular smooth muscle proliferation and neointima formation by regulating the expression of PCNA and p21.

Polymerase delta-interacting protein 2 (Poldip2) is a multi-functional protein with numerous roles in the vasculature, including the regulation of cell apoptosis and migration, as well as extracellular matrix deposition; however, its role in VSMC proliferation and neointimal formation is unknown. In this study, we investigated the role of Poldip2 in intraluminal wire-injury induced neointima formation and proliferation of vascular smooth muscle cells in vitro and in vivo. Poldip2 expression was observed in the intima and media of human atherosclerotic arteries, where it colocalized with proliferating cell nuclear antigen (PCNA).

Polymerase delta-interacting protein 2 deficiency protects against blood-brain barrier permeability in the ischemic brain.

Background: Polymerase δ-interacting protein 2 (Poldip2) is a multifunctional protein that regulates vascular extracellular matrix composition and matrix metalloproteinase (MMP) activity. The blood-brain barrier (BBB) is a dynamic system assembled by endothelial cells, basal lamina, and perivascular astrocytes, raising the possibility that Poldip2 may be involved in maintaining its structure. We investigated the role of Poldip2 in the late BBB permeability induced by cerebral ischemia.

Poldip2 controls vascular smooth muscle cell migration by regulating focal adhesion turnover and force polarization.

Polymerase-δ-interacting protein 2 (Poldip2) interacts with NADPH oxidase 4 (Nox4) and regulates migration; however, the precise underlying mechanisms are unclear. Here, we investigated the role of Poldip2 in focal adhesion turnover, as well as traction force generation and polarization. Poldip2 overexpression (AdPoldip2) in vascular smooth muscle cells (VSMCs) impairs PDGF-induced migration and induces a characteristic phenotype of long cytoplasmic extensions.

Polymerase delta interacting protein 2 sustains vascular structure and function.

Objective: On the basis of previous evidence that polymerase delta interacting protein 2 (Poldip2) increases reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (Nox4) activity in vascular smooth muscle cells, we hypothesized that in vivo knockdown of Poldip2 would inhibit reactive oxygen species production and alter vascular function.

Approach And Results: Because homozygous Poldip2 deletion is lethal, Poldip2(+/-) mice were used. Poldip2 mRNA and protein levels were reduced by ≈50% in Poldip2(+/-) aorta, with no change in p22phox, Nox1, Nox2, and Nox4 mRNAs.

Functional association of nox1 with p22phox in vascular smooth muscle cells.

The vascular NAD(P)H oxidases constitute important sources of ROS in the vessel wall and have been implicated in vascular disease. Vascular smooth muscle cells (VSMCs) from conduit arteries express two gp91phox homologs, Nox1 and Nox4, of which Nox1 is agonist-sensitive. Because p22phox has been shown to be functionally important in vascular cells stimulated with vasoactive hormones, the relationship of Nox1 and p22phox was investigated in VSMCs from rat and human aortas.

Microtubules regulate angiotensin II type 1 receptor and Rac1 localization in caveolae/lipid rafts: role in redox signaling.

Objective: Microtubules are important in signal transduction temporal-spatial organization. Full expression of angiotensin II (Ang II) signaling in vascular smooth muscle cells (VSMCs) is dependent on the reactive oxygen species (ROS) derived from nicotinamide-adenine dinucleotide phosphate (NAD(P)H) oxidase and the dynamic association of the Ang II type 1 receptor (AT1R) with caveolae/lipid rafts. Translocation of the small GTPase Rac1 to the plasma membrane is an essential step for activation of NAD(P)H oxidase; however, its precise localization in the plasma membrane after agonist stimulation and how it is targeted are unknown.

Distinct subcellular localizations of Nox1 and Nox4 in vascular smooth muscle cells.

Objective: Reactive oxygen species (ROS) that act as signaling molecules in vascular smooth muscle cells (VSMC) and contribute to growth, hypertrophy, and migration in atherogenesis are produced by multi-subunit NAD(P)H oxidases. Nox1 and Nox4, two homologues to the phagocytic NAD(P)H subunit gp91phox, both generate ROS in VSMC but differ in their response to growth factors. We hypothesize that the opposing functions of Nox1 and Nox4 are reflected in their differential subcellular locations.

Upregulation of Nox-based NAD(P)H oxidases in restenosis after carotid injury.

Restenosis, a frequent complication of coronary angioplasty, is associated with increased superoxide (O2*(-)) production. Although the molecular identity of the responsible oxidase is unclear, an NAD(P)H oxidase appears to be involved. In smooth muscle, p22phox and 2 homologues of gp91phox, nox1 and nox4, are expressed, whereas fibroblasts contain gp91phox.