Targeted Disruption of the PME-1 Gene Causes Loss of Demethylated PP2A and Perinatal Lethality in Mice

Silvia Ortega-Gutiérrez,Donmienne Leung,Benjamin F Cravatt,Scott Ficarro,Eric C Peters,Nick Gay

doi:10.1371/journal.pone.0002486

Silvia Ortega-Gutiérrez, Donmienne Leung + Show 4 more

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https://doi.org/10.1371/journal.pone.0002486

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Abstract

BackgroundPhosphoprotein phosphatase 2A (PP2A), a major serine-threonine protein phosphatase in eukaryotes, is an oligomeric protein comprised of structural (A) and catalytic (C) subunits to which a variable regulatory subunit (B) can associate. The C subunit contains a methyl ester post-translational modification on its C-terminal leucine residue, which is removed by a specific methylesterase (PME-1). Methylesterification is thought to control the binding of different B subunits to AC dimers, but little is known about its physiological significance in vivo.Methodology/Principal FindingsHere, we show that targeted disruption of the PME-1 gene causes perinatal lethality in mice, a phenotype that correlates with a virtually complete loss of the demethylated form of PP2A in the nervous system and peripheral tissues. Interestingly, PP2A catalytic activity over a peptide substrate was dramatically reduced in PME-1(−/−) tissues, which also displayed alterations in phosphoproteome content.ConclusionsThese findings suggest a role for the demethylated form of PP2A in maintenance of enzyme function and phosphorylation networks in vivo.

Highlights

Reversible protein phosphorylation regulated by the coordinated action of protein kinases and phosphatases is an essential signaling mechanism for most cellular processes
These findings suggest a role for the demethylated form of phosphatase 2A (PP2A) in maintenance of enzyme function and phosphorylation networks in vivo
Western blotting with an anti-PME-1 antibody confirmed the absence of PME-1 protein in PME-1(2/2) mice (Fig. 2A)

Summary

Introduction

Reversible protein phosphorylation regulated by the coordinated action of protein kinases and phosphatases is an essential signaling mechanism for most cellular processes. Post-translational phosphorylation is predicted to occur on more than 30% of all eukaryotic proteins [1]. PP2A is involved in numerous cellular processes, including signal transduction pathways that regulate mitogenic and survival signals, transcriptional and translational events, and the cell cycle [4,5]. Phosphoprotein phosphatase 2A (PP2A), a major serine-threonine protein phosphatase in eukaryotes, is an oligomeric protein comprised of structural (A) and catalytic (C) subunits to which a variable regulatory subunit (B) can associate. The C subunit contains a methyl ester post-translational modification on its C-terminal leucine residue, which is removed by a specific methylesterase (PME-1). Methylesterification is thought to control the binding of different B subunits to AC dimers, but little is known about its physiological significance in vivo

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