Vascular Extracellular Superoxide Dismutase Modulation

Project: Research project

Project Details


DESCRIPTION (provided by the applicant): Extracellular superoxide dismutase
(ecSOD), a major form of SOD expressed in the vasculature, is a "secretory"
copper-containing enzyme and plays an important role in regulating blood
pressure and endothelial function by modulating the levels of O2 in the
extracellular space. Particularly, in angiotensin H-induced hypertension model,
the excessive 02 is observed in the vessel wall and the hypertension is
ameliorated by treatment with membrane-targeted forms of SOD. Moreover, we have
found that blood pressure and 02 production in the vessel were highly elevated
in ecSOD-deficient mice infused with angiotensin II. Thus, ecS0D is a
potentially important modulator of oxidative phenomena in the pathogenesis of
hypertension. Recently, it has been shown that copper chaperones (CCS) are
critical for copper transport and delivery to copper containing enzymes. Our
preliminary data strongly suggests that CCS with signal peptide (CCS-SP) which
targets to Golgi plays an important role in the transport of copper to ecSOD,
which is required for full activity of the ecSOD. We will propose the following
specific aim to address how ecSOD activity is controlled by copper transport
system such as CCS and copper transporter in the yeast system, vascular cells
and in vivo model of hypertension. In aim 1, we will characterize a role of
copper transport system for full expression of ecSOD activity using the yeast
system. First, by generating several CCS-SP cDNA constructs including the
truncated form, we will determine which region is critical for copper
loading-to ecSOD. Second, we will determine if copper loading to ecSOD requires
MNK, a copper transporter in the trans-Golgi network, using the yeast strain
deficient in MNK. In aim 2, we will identify endogenous copper chaperone for
ecSOD in human aortic smooth muscle cells (HASM) that highly expresses ecSOD,
by using the highly conserved region of CCS as a probe that have detected novel
CCS-like transcript and protein in HASM. Next, we will determine if copper
delivery to ecSOD requires MTNK in mammalian cells, by using the murine
MNK-mutant fibroblast and aorta from MNK-mutant mice. In aim 3, we will examine
the role of copper transport system for ecSOD in blood pressure, vascular O2
production and endothelial function in angiotensin II induced hypertension by
using MNK-mutant mice. These studies will provide new insight into a copper
transport system for ecSOD as a novel modulator of oxidative stress linked to
the pathogenesis of hypertension and as essential to anti-oxidant therapy.
StatusNot started