Regulation of NADPH oxidase in the ischemic brain

• Grant number: 13/24660-0
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: March 02, 2014
• End date: March 01, 2015
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Luiz Roberto Giorgetti de Britto
• Grantee: Marina Sorrentino Hernandes
• Supervisor: Kathy K. Griendling
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Emory University, United States

Abstract

The Nox family of superoxide and hydrogen peroxide-producing proteins has emerged as an important source of reactive oxygen species in several neurodegenerative conditions. Seven Nox isoforms have been identified, namely Nox1, Nox2 (also known as gp91phox), Nox3, Nox4, Nox5, and Dual Oxidase 1 and 2 (Duox1 and Duox2), each one with their own specific regulatory subunities and mechanisms. Nox1-4 isoforms are widely expressed throughout the brain structures, whereas in brain endothelial cells of cerebral arteries only the presence of Nox1, Nox2 and Nox4 mRNA has been identified. Nox4 has a particularly high expression in those cells, suggesting a more prominent involvement of this isoform in the control of the vascular tone. Unlike Nox1-3, it was assumed that the main mechanism by which Nox-4 is regulated is at the mRNA level, rather than by pos-translational protein modifications. However, it has been recently demonstrated in vascular smooth muscle cells that polymerase (DNA-directed) delta interacting protein 2 (Poldip2), associates with p22phox to activate Nox4. The Nox4/p22phox/Poldip2 complex seems to act as a modulator of several critical cellular processes such as cytoskeletal reorganization and cellular migration. Nox enzymes have attracted progressively interest as key mediators of neurodegeneration induced by stroke and reperfusion. It has been demonstrated that Nox2 and Nox4 are implicated in brain edema and neurodegeneration induced by ischemic stroke. However, recent advances in the understanding of Nox4-mediated tissue and vascular damage highlighted promising inhibitory strategies that specifically target Nox4. Therefore, our specific aim is to investigate the possible involvement of Polipd2, a Nox4 regulatory protein, in ischemic stroke induced by transient middle cerebral artery occlusion. To specifically test this hypothesis, transgenic mice overexpressing Nox4, Poldip2+/- mice (homozygous Poldip2 deletion is lethal), as well as Poldip2+/- crossed with mice overexpressing Nox4 will be used throughout this study. As specific aims Nox4 and Poldip2 gene expression and protein expression will be evaluated in the ischemic brain. The stroke area, neurodegeneration and neuroinflammation will be also investigated in the different mice strains after stroke induction. Furthermore, the stroke volume, cerebral perfusion and angiogenesis will also be evaluated in the ischemic brain and compared among the different groups of mice. (AU)