Visit our Expo - Redox and Inflammation signaling 2012

V. Phosphatases as key cell signaling intermediates Poster V, 6
Regulation of SHP-2 protein tyrosine phosphatase by Angiotensin II-derived reactive
oxygen species in hypertensive and normotensive rats- Evidence of oxidation of protein
tyrosine phosphatases in hypertension
Fatiha Tabet1, Ernesto L. Schiffrin2, Rhian M. Touyz1.
1Ottawa Health Research Institute, University of Ottawa, Health Sciences Building,
304/451 Smyth Road, Ottawa, Ontario K1H 8M5, Canada. E-mail: ftabet@uottawa.ca,
E-mail: rtouyz@uottawa.ca
2Experimental Hypertension Laboratory, Clinical Research Institute of Montreal, 110
Pine Av. West, Montreal, Quebec H2W 1R7, Canada. E-mail:
ernesto.schiffrin@ircm.qc.ca
Reactive Oxygen Species (ROS) act as signaling molecules that regulate activation of MAP
kinases. We recently demonstrated that angiotensin II (Ang II)-stimulated tyrosine kinases
play a role in redox-sensitive activation of MAP kinases and that in vascular smooth muscle
cells (VSMCs) from hypertensive rats (SHR) responses are enhanced. In the present study we
tested the hypothesis that Ang II-induced ROS production augments tyrosine
phosphorylation-dependent signaling in SHR as compared to normotensive rats WKY through
differential activation of intracellular SHP-2 tyrosine phosphatase expression and activation,
and through reversible inactivation of cellular PTPs. Mesenteric artery VSMCs of 16-week
WKY and SHR rats were studied. Cells were stimulated with Ang II (10-7mol/l). The
expression and activation (0-30 min) of SHP-2 was evaluated using immunoblotting analysis.
The role of AT-1 and AT-2 receptors in Ang II-induced activation de SHP-2 was evaluated
using AT-1 and AT-2 receptor inhibitors Valsartan and PD123319, respectively. The “In-Gel”
PTP Assay was used to determine whether PTPs in response to Ang II (10-7mol/l, 0-60 min)
or H2O2 (0.1-200µM, 10 min), are susceptible to oxidation. GST-FER fusion protein was
used as a protein tyrosine kinase source for phosphorylation of the [$-32P]-labeled poly (4:1)
Glu-Tyr substrate. In the basal state, SHP-2 expression (p