Alfiya T Bikineyeva

Publications of Alfiya T Bikineyeva

• Therapeutic targeting of mitochondrial superoxide in hypertension.

  Authors: Anna E Dikalova, Alfiya T Bikineyeva, Klaudia Budzyn, Rafal R Nazarewicz, Louise McCann, William Lewis, David G Harrison, Sergey I Dikalov

  Circulation research. 05/2010; 107(1):106-16.

  Superoxide (O2(-) ) has been implicated in the pathogenesis of many human diseases including hypertension; however, commonly used antioxidants have proven ineffective in clinical trials. It isSuperoxide (O2(-) ) has been implicated in the pathogenesis of many human diseases including hypertension; however, commonly used antioxidants have proven ineffective in clinical trials. It is possible that these agents are not adequately delivered to the subcellular sites of superoxide production. Because the mitochondria are important sources of reactive oxygen species, we postulated that mitochondrial targeting of superoxide scavenging would have therapeutic benefit. In this study, we found that the hormone angiotensin (Ang II) increased endothelial mitochondrial superoxide production. Treatment with the mitochondria-targeted antioxidant mitoTEMPO decreased mitochondrial O2(-), inhibited the total cellular O2(-), reduced cellular NADPH oxidase activity, and restored the level of bioavailable NO. These effects were mimicked by overexpressing the mitochondrial MnSOD (SOD2), whereas SOD2 depletion with small interfering RNA increased both basal and Ang II-stimulated cellular O2(-). Treatment of mice in vivo with mitoTEMPO attenuated hypertension when given at the onset of Ang II infusion and decreased blood pressure by 30 mm Hg following establishment of both Ang II-induced and DOCA salt hypertension, whereas a similar dose of nontargeted TEMPOL was not effective. In vivo, mitoTEMPO decreased vascular O2(-), increased vascular NO production and improved endothelial-dependent relaxation. Interestingly, transgenic mice overexpressing mitochondrial SOD2 demonstrated attenuated Ang II-induced hypertension and vascular oxidative stress similar to mice treated with mitoTEMPO. These studies show that mitochondrial O2(-) is important for the development of hypertension and that antioxidant strategies specifically targeting this organelle could have therapeutic benefit in this and possibly other diseases.

• Distinct roles of Nox1 and Nox4 in basal and angiotensin II-stimulated superoxide and hydrogen peroxide production.

  Authors: Sergey I Dikalov, Anna E Dikalova, Alfiya T Bikineyeva, Harald H H W Schmidt, David G Harrison, Kathy K Griendling

  Free radical biology & medicine. 09/2008;

  NADPH oxidases are major sources of superoxide (O(2)(-)) and hydrogen peroxide (H(2)O(2)) in vascular cells. Production of these reactive oxygen species (ROS) is essential for cell proliferation andNADPH oxidases are major sources of superoxide (O(2)(-)) and hydrogen peroxide (H(2)O(2)) in vascular cells. Production of these reactive oxygen species (ROS) is essential for cell proliferation and differentiation, while ROS overproduction has been implicated in hypertension and atherosclerosis. It is known that the heme-containing catalytic subunits Nox1 and Nox4 are responsible for oxygen reduction in vascular smooth muscle cells from large arteries. However, the exact mechanism of ROS production by NADPH oxidases is not completely understood. We hypothesized that Nox1 and Nox4 play distinct roles in basal and angiotensin II (AngII)-stimulated production of O(2)(-) and H(2)O(2). Nox1 and Nox4 expression in rat aortic smooth muscle cells (RASMCs) was selectively reduced by treatment with siNox4 or antisense Nox1 adenovirus. Production of O(2)(-) and H(2)O(2) in intact RASMCs was analyzed by dihydroethidium and Amplex Red assay. Activity of NADPH oxidases was measured by NADPH-dependent O(2)(-) and H(2)O(2) production using electron spin resonance (ESR) and 1-hydroxy-3-carboxypyrrolidine (CPH) in the membrane fraction in the absence of cytosolic superoxide dismutase. It was found that production of O(2)(-) by quiescent RASMC NADPH oxidases was five times less than H(2)O(2) production. Stimulation of cells with AngII led to a 2-fold increase of O(2)(-) production by NADPH oxidases, with a small 15 to 30% increase in H(2)O(2) formation. Depletion of Nox4 in RASMCs led to diminished basal H(2)O(2) production, but did not affect O(2)(-) or H(2)O(2) production stimulated by AngII. In contrast, depletion of Nox1 in RASMCs inhibited production of O(2)(-) and AngII-stimulated H(2)O(2) in the membrane fraction and intact cells. Our data suggest that Nox4 produces mainly H(2)O(2), while Nox1 generates mostly O(2)(-) that is later converted to H(2)O(2.) Therefore, Nox4 is responsible for basal H(2)O(2) production, while O(2)(-) production in nonstimulated and AngII-stimulated cells depends on Nox1. The difference in the products generated by Nox1 and Nox4 may help to explain the distinct roles of these NADPH oxidases in cell signaling. These findings also provide important insight into the origin of H(2)O(2) in vascular cells, and may partially account for the limited pharmacological effect of antioxidant treatments with O(2)(-) scavengers that do not affect H(2)O(2).

• Distinct roles of Nox1 and Nox4 in basal and angiotensin II-stimulated superoxide and hydrogen peroxide production

  Authors: Sergey I. Dikalov, Anna E. Dikalova, Alfiya T. Bikineyeva, Harald H.H.W. Schmidt, David G. Harrison, Kathy K. Griendling

  Free Radical Biology and Medicine.

  NADPH oxidases are major sources of superoxide (O2●−) and hydrogen peroxide (H2O2) in vascular cells. Production of these reactive oxygen species (ROS) is essential for cell proliferation andNADPH oxidases are major sources of superoxide (O2●−) and hydrogen peroxide (H2O2) in vascular cells. Production of these reactive oxygen species (ROS) is essential for cell proliferation and differentiation, while ROS overproduction has been implicated in hypertension and atherosclerosis. It is known that the heme-containing catalytic subunits Nox1 and Nox4 are responsible for oxygen reduction in vascular smooth muscle cells from large arteries. However, the exact mechanism of ROS production by NADPH oxidases is not completely understood. We hypothesized that Nox1 and Nox4 play distinct roles in basal and angiotensin II (AngII)-stimulated production of O2●− and H2O2. Nox1 and Nox4 expression in rat aortic smooth muscle cells (RASMCs) was selectively reduced by treatment with siNox4 or antisense Nox1 adenovirus. Production of O2●− and H2O2 in intact RASMCs was analyzed by dihydroethidium and Amplex Red assay. Activity of NADPH oxidases was measured by NADPH-dependent O2●− and H2O2 production using electron spin resonance (ESR) and 1-hydroxy-3-carboxypyrrolidine (CPH) in the membrane fraction in the absence of cytosolic superoxide dismutase. It was found that production of O2●− by quiescent RASMC NADPH oxidases was five times less than H2O2 production. Stimulation of cells with AngII led to a 2-fold increase of O2●− production by NADPH oxidases, with a small 15 to 30% increase in H2O2 formation. Depletion of Nox4 in RASMCs led to diminished basal H2O2 production, but did not affect O2●− or H2O2 production stimulated by AngII. In contrast, depletion of Nox1 in RASMCs inhibited production of O2●− and AngII-stimulated H2O2 in the membrane fraction and intact cells. Our data suggest that Nox4 produces mainly H2O2, while Nox1 generates mostly O2●− that is later converted to H2O2. Therefore, Nox4 is responsible for basal H2O2 production, while O2●− production in nonstimulated and AngII-stimulated cells depends on Nox1. The difference in the products generated by Nox1 and Nox4 may help to explain the distinct roles of these NADPH oxidases in cell signaling. These findings also provide important insight into the origin of H2O2 in vascular cells, and may partially account for the limited pharmacological effect of antioxidant treatments with O2●− scavengers that do not affect H2O2.