Brain PP2A is modified by thiol-disulfide exchange and intermolecular disulfide formation

Foley, Timothy D.; Kintner, Marissa E.

doi:10.1016/j.bbrc.2005.03.108

Cited by 24 publications

(19 citation statements)

References 21 publications

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“…A number of phosphatases have been linked to ERK inactivation, including the serine/threonine phosphatase PP2A, a number of tyrosine phosphatases, such as HePTP and STEP, and the family of dual specificity phosphatases, MKPs. Although it is known that PP2A is regulated by phosphorylation and methylation of the catalytic subunit, some studies indicate that PP2A may be regulated by redox modification of cysteine residues in the same way that PTPs are inactivated by oxidant modification of a cysteine in the catalytic domain (29,30). Other studies, using brain, cultured T cells, and fibroblasts have shown that the oxidant stress hydrogen peroxide can increase ERK activity via a decrease in phosphatase activity, including PP2A and protein/tyrosine phosphatases (29,42,43).…”

Section: Discussionmentioning

confidence: 99%

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Macrophages Survive Hyperoxia via Prolonged ERK Activation Due to Phosphatase Down-regulation

Nyunoya

Monick

Powers

et al. 2005

Journal of Biological Chemistry

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Macrophages exposed to hyperoxia in the lung continue to survive for prolonged periods. We previously reported (Nyunoya, T., Powers, L. S., Yarovinsky, T. O., Butler, N. S., Monick, M. M., and Hunninghake, G. W. (2003) J. Biol. Chem. 278, 36099 -36106) that hyperoxia induces cell cycle arrest and sustained extracellular signal-related kinase (ERK) activity in macrophages. In this study, we determined the mechanisms of hyperoxiainduced ERK activation and how ERK activity plays a pro-survival role in hyperoxia-exposed cells. Inhibition of ERK activity decreased survival of hyperoxia-exposed macrophages. This was due, at least in part, to down-regulation of the pro-apoptotic Bcl-2 family member, BimEL. In determining the mechanism of ERK activation by hyperoxia, we found that ERK activation was not associated with hyperoxia-induced activation of the upstream ERK kinase mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2. When we examined the ability of whole cell lysates from hyperoxia-exposed cells to dephosphorylate purified phosphorylated ERK, we found decreased ERK-directed phosphatase activity. Two particular ERK-directed phosphatases (protein phosphatase 2A and MAPK phosphatase-3) demonstrated decreased activity in hyperoxia-exposed cells. Moreover, whole cell lysates from normoxia-exposed cells depleted of PP2A or MAPK phosphatase-3 were also less able to dephosphorylate ERK. These data demonstrate that, in hyperoxia-exposed macrophages, sustained activation of ERK due to phosphatase down-regulation permits macrophage survival via effects on the balance between pro-and antiapoptotic Bcl-2 family proteins.

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Section: Discussionmentioning

confidence: 99%

“…The serine/threonine phosphatase PP2A has also been shown to be negatively regulated by redox modulation of a cysteine (29,30). Because of this known redox-linked negative regulation of phosphatases, we hypothesized that hyperoxia induces prolonged ERK activation via inactivation of one or more phosphatases involved in ERK regulation.…”

mentioning

confidence: 99%

Macrophages Survive Hyperoxia via Prolonged ERK Activation Due to Phosphatase Down-regulation

Nyunoya

Monick

Powers

et al. 2005

Journal of Biological Chemistry

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“…We have shown previously that the phosphatase activity towards phosphothreonine peptide substrates in subcellular fractions from rat brain cerebral cortex was attributable mainly to PP2A [9,15]. Thus, the function and interaction with other brain proteins of PP2A can be studied conveniently in these crude fractions.…”

Section: Introductionmentioning

confidence: 95%

“…Measurement of PP2A activity PP2A activity was measured by minor modifications of methods described previously [9,15]. Specifically, the HSS fraction (20 lg) was pre-incubated for the desired period of time at 37°C in phosphatase buffer (defined above) with or without the compounds under study (DTT, 2-mercaptoethanol, TCEP, okadaic acid, or PAO) in a final volume of 200 ll.…”

Section: Analysis Of Total Protein By Sds-polyacrylamide Gel Electropmentioning

confidence: 99%

Oxidative Inhibition of Protein Phosphatase 2A Activity: Role of Catalytic Subunit Disulfides

et al. 2007

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A molecular basis for the inhibition of brain protein phosphatase 2A (PP2A) activity by oxidative stress was examined in a high-speed supernatant (HSS) fraction from rat cerebral cortex. PP2A activity was subject to substantial disulfide reducing agent-reversible inhibition in the HSS fraction. Results of gel electrophoresis support the conclusions that inhibition of PP2A activity was associated with the both the disulfide cross-linking of the catalytic subunit (PP2A(C)) of the enzyme to other brain proteins and with the formation of an apparent novel intramolecular disulfide bond in PP2A(C). Additional findings that the vicinal dithiol cross-linking reagent phenylarsine oxide (PAO) produced a potent dithiothreitol-reversible inhibition of PP2A activity suggest that the cross-linking of PP2A(C) vicinal thiols to form an intramolecular disulfide bond may be sufficient to inhibit PP2A activity under oxidative stress. We propose that the dithiol-disulfide equilibrium of a vicinal thiol pair of PP2A(C) may confer redox sensitivity on cellular PP2A.

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“…Our hypothesis would be that two of ten cysteine residues present in PP2Ac, namely cysteine 269 and cysteine 272 could represent a target for formation of disulfide bonds catalyzed by NRX. Significantly, a recent paper reported that brain PP2A is susceptible to reversible inhibitory modification by thiol-disulfide exchange [27].…”

Section: Discussionmentioning

confidence: 99%

Interaction of nucleoredoxin with protein phosphatase 2A

et al. 2006

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A trimeric protein phosphatase 2A (PP2A T55 ) composed of the catalytic (PP2Ac), structural (PR65/A), and regulatory (PR55/B) subunits was isolated from rabbit skeletal muscle by thiophosphorylase affinity chromatography, and contained two additional proteins of 54 and 55 kDa, respectively. The 54 kDa protein was identified as eukaryotic translation termination factor 1 (eRF1) and as a PP2A interacting protein [Andjelkovic et al. (1996) EMBO J. 15,[101][102][103][104][105][106][107][108][109][110][111][112]. The 55 kDa protein is now identified as nucleoredoxin (NRX). The formation of a complex between GST-NRX, PP2A C and PP2A D was demonstrated by pull-down experiments with purified forms of PP2A, and by immunoprecipitation of HA-tagged NRX expressed in HEK293 cells complexed endogenous PP2A subunits. Analysis of PP2A activity in the presence of GST-NRX showed that NRX competed with polycations for both stimulatory and inhibitory effects on different forms of PP2A.

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Brain PP2A is modified by thiol-disulfide exchange and intermolecular disulfide formation

Cited by 24 publications

References 21 publications

Macrophages Survive Hyperoxia via Prolonged ERK Activation Due to Phosphatase Down-regulation

Macrophages Survive Hyperoxia via Prolonged ERK Activation Due to Phosphatase Down-regulation

Oxidative Inhibition of Protein Phosphatase 2A Activity: Role of Catalytic Subunit Disulfides

Interaction of nucleoredoxin with protein phosphatase 2A

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