Mice lacking phosphatase PP2A subunit PR61/B’δ (Ppp2r5d) develop spatially restricted tauopathy by deregulation of CDK5 and GSK3β

Functional diversity of protein phosphatase 2A (PP2A) enzymes mainly results from their association with distinct regulatory subunits. To analyze the functions of one such holoenzyme in vivo, we generated mice lacking PR61/B’δ (B56δ), a subunit highly expressed in neural tissues. In PR61/B’δ-null mice the microtubule-associated protein tau becomes progressively phosphorylated at pathological epitopes in restricted brain areas, with marked immunoreactivity for the misfolded MC1-conformation but without neurofibrillary tangle formation. Behavioral tests indicated impaired sensorimotor but normal cognitive functions. These phenotypical characteristics were further underscored in PR61/B’δ-null mice mildly overexpressing human tau. PR61/B’δ-containing PP2A (PP2AT61δ) poorly dephosphorylates tau in vitro, arguing against a direct dephosphorylation defect. Rather, the activity of glycogen synthase kinase-3β, a major tau kinase, was found increased, with decreased phosphorylation of Ser-9, a putative cyclin-dependent kinase 5 (CDK5) target. Accordingly, CDK5 activity is decreased, and its cellular activator p35, strikingly absent in the affected brain areas. As opposed to tau, p35 is an excellent PP2AT61δ substrate. Our data imply a nonredundant function for PR61/B’δ in phospho-tau homeostasis via an unexpected spatially restricted mechanism preventing p35 hyperphosphorylation and its subsequent degradation.

[1]  C. Phiel,et al.  Functions of B56-containing PP2As in major developmental and cancer signaling pathways. , 2010, Life sciences.

[2]  S. Strack,et al.  Protein phosphatase 2A carboxymethylation and regulatory B subunits differentially regulate mast cell degranulation. , 2010, Cellular signalling.

[3]  J. Götz,et al.  Animal models reveal role for tau phosphorylation in human disease. , 2010, Biochimica et biophysica acta.

[4]  A. Bonci,et al.  Protein Phosphatase 2A and Glycogen Synthase Kinase 3 Signaling Modulate Prepulse Inhibition of the Acoustic Startle Response by Altering Cortical M-Type Potassium Channel Activity , 2010, The Journal of Neuroscience.

[5]  D. Burgess,et al.  PP2A T61 epsilon is an inhibitor of MAP4K3 in nutrient signaling to mTOR. , 2010, Molecular cell.

[6]  I. Landrieu,et al.  Alzheimer disease specific phosphoepitopes of Tau interfere with assembly of tubulin but not binding to microtubules , 2009, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[7]  R. Bernards,et al.  Protein phosphatase 2A regulatory subunits and cancer. , 2009, Biochimica et biophysica acta.

[8]  S. Strack,et al.  The Protein Phosphatase 2A Regulatory Subunits B′β and B′δ Mediate Sustained TrkA Neurotrophin Receptor Autophosphorylation and Neuronal Differentiation , 2008, Molecular and Cellular Biology.

[9]  Yigong Shi,et al.  Structure of a protein phosphatase 2A holoenzyme: insights into B55-mediated Tau dephosphorylation. , 2008, Molecular cell.

[10]  Paul Greengard,et al.  A phosphatase cascade by which rewarding stimuli control nucleosomal response , 2008, Nature.

[11]  Lili Wang,et al.  Interplay between Cyclin-Dependent Kinase 5 and Glycogen Synthase Kinase 3β Mediated by Neuregulin Signaling Leads to Differential Effects on Tau Phosphorylation and Amyloid Precursor Protein Processing , 2008, The Journal of Neuroscience.

[12]  V. Janssens,et al.  PP2A holoenzyme assembly: in cauda venenum (the sting is in the tail). , 2008, Trends in biochemical sciences.

[13]  Anna Kremer,et al.  Neurodegeneration and neuroinflammation in cdk5/p25-inducible mice: a model for hippocampal sclerosis and neocortical degeneration. , 2008, The American journal of pathology.

[14]  J. Goris,et al.  Control of mitotic exit by PP2A regulation of Cdc25C and Cdk1 , 2007, Proceedings of the National Academy of Sciences.

[15]  V. Janssens,et al.  Selection of Protein Phosphatase 2A Regulatory Subunits Is Mediated by the C Terminus of the Catalytic Subunit* , 2007, Journal of Biological Chemistry.

[16]  A. Nairn,et al.  Regulation of Protein Phosphatase Inhibitor-1 by Cyclin-dependent Kinase 5* , 2007, Journal of Biological Chemistry.

[17]  Angus C Nairn,et al.  Protein kinase A activates protein phosphatase 2A by phosphorylation of the B56δ subunit , 2007, Proceedings of the National Academy of Sciences.

[18]  W. Hahn,et al.  Role for the PP2A/B56delta phosphatase in regulating 14-3-3 release from Cdc25 to control mitosis. , 2006, Cell.

[19]  F. Plattner,et al.  The Roles of Cyclin-dependent Kinase 5 and Glycogen Synthase Kinase 3 in Tau Hyperphosphorylation* , 2006, Journal of Biological Chemistry.

[20]  J. Götz,et al.  Altered phosphorylation of cytoskeletal proteins in mutant protein phosphatase 2A transgenic mice. , 2006, Biochemical and biophysical research communications.

[21]  L. Petrucelli,et al.  HSP induction mediates selective clearance of tau phosphorylated at proline‐directed Ser/Thr sites but not KXGS (MARK) sites , 2006, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[22]  H. Paudel,et al.  Glycogen synthase kinase 3beta phosphorylates Alzheimer's disease-specific Ser396 of microtubule-associated protein tau by a sequential mechanism. , 2006, Biochemistry.

[23]  M. Iadarola,et al.  Cyclin-dependent kinase 5 activity regulates pain signaling. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[24]  F. van Leuven,et al.  Changed Conformation of Mutant Tau-P301L Underlies the Moribund Tauopathy, Absent in Progressive, Nonlethal Axonopathy of Tau-4R/2N Transgenic Mice* , 2005, Journal of Biological Chemistry.

[25]  C. van Hoof,et al.  PP2A: the expected tumor suppressor. , 2005, Current opinion in genetics & development.

[26]  G. Johnson,et al.  Tau phosphorylation in neuronal cell function and dysfunction , 2004, Journal of Cell Science.

[27]  G. Pigino,et al.  A novel CDK5‐dependent pathway for regulating GSK3 activity and kinesin‐driven motility in neurons , 2004, The EMBO journal.

[28]  S. Speciale,et al.  Altered Expression Levels of the Protein Phosphatase 2A ABαC Enzyme Are Associated with Alzheimer Disease Pathology , 2004, Journal of neuropathology and experimental neurology.

[29]  J. Vermeesch,et al.  Genomic organisation, chromosomal localisation tissue distribution and developmental regulation of the PR61/B' regulatory subunits of protein phosphatase 2A in mice. , 2004, Journal of molecular biology.

[30]  R. DePinho,et al.  Decreased Cyclin-Dependent Kinase 5 (cdk5) Activity Is Accompanied by Redistribution of cdk5 and Cytoskeletal Proteins and Increased Cytoskeletal Protein Phosphorylation in p35 Null Mice , 2003, The Journal of Neuroscience.

[31]  V. Centonze,et al.  PKA, PKC, and the protein phosphatase 2A influence HAND factor function: a mechanism for tissue-specific transcriptional regulation. , 2003, Molecular cell.

[32]  R. Nitsch,et al.  Diversity, developmental regulation and distribution of murine PR55/B subunits of protein phosphatase 2A , 2002, The European journal of neuroscience.

[33]  H. Soininen,et al.  Influence of phosphorylation of p35, an activator of cyclin-dependent kinase 5 (cdk5), on the proteolysis of p35. , 2002, Brain research. Molecular brain research.

[34]  Qing Tian,et al.  Role of Serine/Threonine Protein Phosphatase in Alzheimer’s Disease , 2002, Neurosignals.

[35]  R. Nitsch,et al.  Reduced protein phosphatase 2A activity induces hyperphosphorylation and altered compartmentalization of tau in transgenic mice. , 2001, The Journal of biological chemistry.

[36]  R. Nitsch,et al.  Formation of Neurofibrillary Tangles in P301L Tau Transgenic Mice Induced by Aβ42 Fibrils , 2001, Science.

[37]  J. Trojanowski,et al.  PP2A mRNA Expression Is Quantitatively Decreased in Alzheimer's Disease Hippocampus , 2001, Experimental Neurology.

[38]  René Hen,et al.  Decreased nuclear β‐catenin, tau hyperphosphorylation and neurodegeneration in GSK‐3β conditional transgenic mice , 2001 .

[39]  R. Hen,et al.  Decreased nuclear beta-catenin, tau hyperphosphorylation and neurodegeneration in GSK-3beta conditional transgenic mice. , 2001, The EMBO journal.

[40]  M. Mercken,et al.  Glycogen Synthase Kinase-3β Phosphorylates Protein Tau and Rescues the Axonopathy in the Central Nervous System of Human Four-repeat Tau Transgenic Mice* , 2000, The Journal of Biological Chemistry.

[41]  P. Davies,et al.  Conformational change as one of the earliest alterations of tau in Alzheimer’s disease , 2000, Neurobiology of Aging.

[42]  L. Tsai,et al.  Neurotoxicity induces cleavage of p35 to p25 by calpain , 2000, Nature.

[43]  H. Geerts,et al.  Prominent axonopathy in the brain and spinal cord of transgenic mice overexpressing four-repeat human tau protein. , 1999, The American journal of pathology.

[44]  G. Bloom,et al.  Molecular Interactions among Protein Phosphatase 2A, Tau, and Microtubules , 1999, The Journal of Biological Chemistry.

[45]  K. Ishiguro,et al.  Okadaic acid-stimulated degradation of p35, an activator of CDK5, by proteasome in cultured neurons. , 1998, Biochemical and biophysical research communications.

[46]  B. Hemmings,et al.  Delayed embryonic lethality in mice lacking protein phosphatase 2A catalytic subunit Calpha. , 1998, Proceedings of the National Academy of Sciences of the United States of America.

[47]  L. Tsai,et al.  p35, the Neuronal-specific Activator of Cyclin-dependent Kinase 5 (Cdk5) Is Degraded by the Ubiquitin-Proteasome Pathway* , 1998, The Journal of Biological Chemistry.

[48]  F. Ebner,et al.  Brain protein phosphatase 2A: Developmental regulation and distinct cellular and subcellular localization by B subunits , 1998, The Journal of comparative neurology.

[49]  G. Jicha,et al.  Alz‐50 and MC‐1, a new monoclonal antibody raised to paired helical filaments, recognize conformational epitopes on recombinant tau , 1997, Journal of neuroscience research.

[50]  G. Bloom,et al.  Regulation of the Phosphorylation State and Microtubule-Binding Activity of Tau by Protein Phosphatase 2A , 1996, Neuron.

[51]  Veeranna,et al.  Targeted disruption of the cyclin-dependent kinase 5 gene results in abnormal corticogenesis, neuronal pathology and perinatal death. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[52]  D. Virshup,et al.  The B56 Family of Protein Phosphatase 2A (PP2A) Regulatory Subunits Encodes Differentiation-induced Phosphoproteins That Target PP2A to Both Nucleus and Cytoplasm* , 1996, The Journal of Biological Chemistry.

[53]  E. Mandelkow,et al.  Dephosphorylation of tau protein and Alzheimer paired helical filaments by calcmeurin and phosphatase‐2A , 1993, FEBS letters.

[54]  W. Merlevede,et al.  A specific immunoprecipitation assay for the protein kinase FA/glycogen synthase kinase 3. , 1993, Analytical biochemistry.

[55]  P. Cohen,et al.  p42 map kinase phosphorylation sites in microtubule‐associated protein tau are dephosphorylated by protein phosphatase 2A1 Implications for Alzheimer's disease , 1992, FEBS letters.

[56]  P. Agostinis,et al.  Specificity of the polycation-stimulated (type-2A) and ATP,Mg-dependent (type-1) protein phosphatases toward substrates phosphorylated by P34cdc2 kinase. , 1992, European journal of biochemistry.

[57]  W. Merlevede,et al.  Purification and properties of polycation-stimulated phosphorylase phosphatases from rabbit skeletal muscle. , 1987, The Journal of biological chemistry.