Inhibition of Protein-tyrosine Phosphatases by Mild Oxidative Stresses Is Dependent on S-Nitrosylation

Abstract

Previous studies have shown that a Ca2؉ -dependent nitric-oxide synthase (NOS) is activated as part of a cellular response to low doses of ionizing radiation. Genetic and pharmacological inhibitor studies linked this NO signaling to the radiation-induced activation of ERK1/2. Herein, a mechanism for the radiation-induced activation of Tyr phosphorylation-dependent pathways (e.g. ERK1/2) involving the inhibition of protein-Tyr phosphatases (PTPs) by S-nitrosylation is tested. The basis for this mechanism resides in the redox-sensitive active site Cys in PTPs. These studies also examined oxidative stress induced by low concentrations of H 2 O 2 . ionophore, ionomycin, also stimulated NOS activity, and this was associated with an enhanced S-nitrosylation of the active site Cys 453 determined by isolation of S-nitrosylated wild type but not active site Cys 453 3 Ser SHP-1 mutant by the "biotin-switch" method. Thus, one consequence of oxidative stimulation of NO generation is S-nitrosylation and inhibition of PTPs critical in cellular signal transduction pathways. These results support the conclusion that a mild oxidative signal is converted to a nitrosative one due to the better redox signaling properties of NO. S-Nitrosylation

SOCS1 protects protein tyrosine phosphatases by thioredoxin upregulation and attenuates Jaks to suppress ROS-mediated apoptosis

“…It is proposed that ROS induces PTP inactivation by reversible oxidation of thiol groups to form disulfide bonds (Denu and Tanner, 1998), which are picked up by the redox-sensing proteins such as thioredoxin or glutathione, which restore the PTP activities by reducing oxidized PTPs (Reth, 2002). In addition to oxidation, S-nitrosylation of PTP has been suggested as a mechanism of PTP inhibition induced by mild oxidative stress (Barrett et al, 2005). We cannot rule out the possibility that SHP1 or CD45 undergoes Snitrosylation on TNF-a or H 2 O 2 treatment in T cells under the assay conditions employed, which may later proceed to oxidation to sulfenic acid formation.…”

Redox-based regulation of signal transduction: Principles, pitfalls, and promises

“…Indeed, in stimulated macrophages that produce H 2 O 2 on the outside of the cell, H 2 O 2 -dependent PTP1B glutathionylation occurs, although the rate constant for formation of the sulfenic acid intermediate suggests that it would not be the intermediate [120,121]. PTP1B, PTP, PTEN and SHP2 are also substrates for inhibitory S-nitrosylation [1,[122][123][124][125][126][127], and singlet oxygen also inactivates protein tyrosine phosphatase-1B by oxidation of the active site cysteine [128], demonstrating that this class of proteases is a target for inhibition via multiple cysteine oxidations.…”

Nitric Oxide and Cancer Development

“…Nedospasov et al 103 compounds such as nitroso glutathione 98 . The S-nitrosylation of some protein tyrosine phosphatases (PTPs) has been demonstrated 102,[104][105][106] . It should be noted that even though NO mediates inactivation of PTP1B 104,106,107 , it can be reactivated by chemical treatment with dithiothreitol, but there is nothing known about possible natural occurring systems that may reactivate the SNO modified proteins.…”

“…In fact, a general examination of the 100 or so proteins that have been shown to be S-nitrosylated in biological systems, see for example [99][100][101] , have demonstrated that they have a degenerate consensus motif as such X(K/R/H)C(D/E). Thus the target cysteine is juxtaposed between a basic amino acid on one side, and an acidic amino acid on the other side 102 . It should be noted that the consensus motif can be accomplished by juxtaposing the basic and acidic amino acids near the target cysteine, either spatially as dictated by the protein conformation, or in a defined linear sequence.…”