Differential Inactivation of Postsynaptic Density‐Associated and Soluble Ca<sup>2+</sup>/Calmodulin‐Dependent Protein Kinase II by Protein Phosphatases 1 and 2A

Strack, Stefan; Barban, Mary Ann; Wadzinski, Brian E.; Colbran, Roger J.

doi:10.1046/j.1471-4159.1997.68052119.x

Cited by 285 publications

(224 citation statements)

References 39 publications

(51 reference statements)

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“…This scenario would still be interesting, because it suggests that αCaMKII that is at the PSD is kept in a preferentially inactivated state under basal conditions. A possible mechanism for this is differential control by phosphatases at the post-synaptic density compared to elsewhere in the neuron, and indeed it has been demonstrated that T286 is dephosphorylated by different phosphatases depending on if the kinase is PSD-associated or soluble (Strack et al, 1997a). Whatever the explanation of these results, it is clear that our data are incompatible with a model in which T286 phosphorylated αCaMKII is preferentially localized to the PSD and T305 phosphorylated αCaMKII is excluded from the PSD.…”

Section: Discussioncontrasting

confidence: 80%

αCaMKII autophosphorylation levels differ depending on subcellular localization

et al. 2007

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Calcium/calmodulin-dependent protein kinase II (CaMKII) has important roles in many processes in the central nervous system. It is enriched at the post-synaptic density (PSD), a localization which is thought to be critical for many of its proposed neuronal functions. In order to better understand the mechanisms that regulate association of CaMKII with the PSD, we compared the levels of autophosphorylation between PSD-associated kinase and kinase in other parts of the neuron. We were surprised to find that αCaMKII in a PSD-enriched fraction prepared from recovered hippocampal CA1-minislices had a relatively low level of threonine 286 (T286) phosphorylation and a relatively high level of threonine 305 (T305) phosphorylation. Furthermore, when the minislices were subjected to a treatment that mimics ischemic conditions, there was a significant translocation of αCaMKII to the PSD-enriched fraction accompanied with a dramatic reduction in T286 phosphorylation levels throughout the neuron. These findings have important implications for our understanding of the role of autophosphorylation in the localization of CaMKII.

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Section: Discussioncontrasting

confidence: 80%

αCaMKII autophosphorylation levels differ depending on subcellular localization

et al. 2007

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“…It should be noted, however, that, when autophosphorylated on a critical threonine residue, the CaMKII has 1000-fold increased affinity for Ca 2 þ /calmodulin and is active even in the absence of Ca 2 þ /calmodulin (for recent reviews, see Colbran 13 and Hudmon and Schulman 34 ). Since phosphoprotein phosphatase type 2A (PP2A) and phosphoprotein phosphatase type 1 (PP1) catalyze the dephosphorylation of autoactivated CaMKII, 13,35 an obvious pathway for PPinhibitor activation of CaMKII is by blocking its dephosphorylation, 33 thereby circumventing the need for increased Ca i 2 þ . Recently, Howe et al 36 have shown that reactive oxygen radicals can inactivate PP2A and thereby stimulate CaMKII.…”

Section: Discussionmentioning

confidence: 99%

“…To determine protein synthesis activity, the detached cells were centrifuged (400 Â g, 2 min), resuspended in fresh medium containing [ 35 The incubation was terminated by the addition of ice-cold 7% aqueous trichloroacetic acid. The cell precipitates were transferred to tubes, centrifuged (15 000 Â g, 15 min), and the pellet washed three times in 5% trichloroacetic acid and twice in diethyl ether, before dissolving in SDS loading buffer (50 mM Tris-HCl, pH 6.8, 10% glycerol, 2% SDS, 100 mM DTT and 0.05% bromophenol blue).…”

Section: Apoptotic Cell Deathmentioning

confidence: 99%

CaM-kinaseII-dependent commitment to microcystin-induced apoptosis is coupled to cell budding, but not to shrinkage or chromatin hypercondensation

et al. 2005

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The protein phosphatase inhibitor microcystin-LR (MC) induced hepatocyte apoptosis mediated by the calciumcalmodulin-dependent multifunctional protein kinase II (CaM-KII). CaMKII antagonists were added at various times after MC to define for how long the cells depended on CaMKII activity to be committed to execute the various parameters of death. Shrinkage and nonpolarized budding were reversible and not coupled to commitment. A critical commitment step was observed 15-20 min after MC (0.5 lM) addition. After this, CaMKII inhibitors no longer protected against polarized budding, DNA fragmentation, lost protein synthesis capability, and cell disruption. Commitment to chromatin hypercondensation occurred 40 min after MC addition. In conclusion, irreversible death commitment was coupled to polarized budding, but not to shrinkage or chromatin condensation. Antioxidant prevented chromatin condensation when given after the CaMKII-dependent commitment point, suggesting that CaMKII had mediated the accumulation of a second messenger of reactive oxygen species nature.

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“…Immunopurification, Western Blot, and Gel Analysis-The general serine/threonine phosphatase antibody (FL-18) was from Santa Cruz Biotechnology. Antibodies to OGT, PP1␣, PP1␤, PP1␥, PP4, and PP6 have been described previously (12,(22)(23)(24)(25)(26)(27). Negative controls used normal rabbit IgG.…”

Section: Methodsmentioning

confidence: 99%

O-GlcNAc Transferase Is in a Functional Complex with Protein Phosphatase 1 Catalytic Subunits

Wells

Kreppel

Comer

et al. 2004

Journal of Biological Chemistry

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127

113

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A hallmark of signal transduction is the dynamic and inducible post-translational modification of proteins. In addition to the well characterized phosphorylation of proteins, other modifications have been shown to be regulatory, including O-linked ␤-N-acetylglucosamine (O-GlcNAc). O-GlcNAc modifies serine and threonine residues on a myriad of nuclear and cytosolic proteins, and for several proteins there appears to be a reciprocal relationship between phosphorylation and O-GlcNAc modification. Here we report further evidence of this yin-yang relationship by demonstrating that O-GlcNAc transferase, the enzyme that adds O-GlcNAc to proteins, exists in stable and active complexes with the serine/ threonine phosphatases PP1␤ and PP1␥, enzymes that remove phosphate from proteins. The existence of this complex highlights the importance of understanding the dynamic relationship between O-GlcNAc and phosphate in modulating protein function in many cellular processes and disease states such as Alzheimer's disease and type II diabetes.Although there are only 21, counting selenocysteine, genomically encoded mammalian amino acids, post-translational modification results in proteins that contain more than 50 different amino acids (1). Thus, covalent modification of polypeptides plays a major role in the generation of functional polypeptides and adds an extra level of complexity in attempts to understand the proteome (2). While several protein modifications are static, a subset of post-translational modifications is both dynamic and inducible. It is the study of these "regulatory" posttranslational modifications and the enzymes that add and subtract them to proteins that comprises a significant portion of the signal transduction field (3).The most well studied and understood regulatory post-translational modification is phosphorylation (3). Accordingly, a significant body of literature has focused on the kinase superfamily, which makes up more than 2% of the proteins encoded by the human genome (4). Interestingly, in humans there appear to be only about 15 catalytic serine/threonine protein phosphatases (PPP subfamily) compared with literally hundreds of serine/threonine kinases (4). Thus, understanding how protein dephosphorylation is regulated has been an area of intense study for the last two decades (5, 6). One emerging theme is that the catalytic phosphatases have binding partners that regulate their localization and activity (7).Similar to phosphorylation, O-linked ␤-N-acetylglucosamine (O-GlcNAc) modification of nuclear and cytosolic proteins is an abundant, dynamic, and inducible post-translational modification (8 -10). However, unlike kinases, there appears to be only one O-GlcNAc transferase catalytic subunit (OGT, 1 the enzyme that adds O-GlcNAc to proteins) in mammals (11). Similar to phosphatases, it has been proposed that OGT is regulated by a multitude of binding partners as well as post-translational modification and alternative splicing (12, 13). It has been demonstrated recently that OGT interacts with sever...

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Differential Inactivation of Postsynaptic Density‐Associated and Soluble Ca²⁺/Calmodulin‐Dependent Protein Kinase II by Protein Phosphatases 1 and 2A

Cited by 285 publications

References 39 publications

αCaMKII autophosphorylation levels differ depending on subcellular localization

αCaMKII autophosphorylation levels differ depending on subcellular localization

CaM-kinaseII-dependent commitment to microcystin-induced apoptosis is coupled to cell budding, but not to shrinkage or chromatin hypercondensation

O-GlcNAc Transferase Is in a Functional Complex with Protein Phosphatase 1 Catalytic Subunits

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Differential Inactivation of Postsynaptic Density‐Associated and Soluble Ca2+/Calmodulin‐Dependent Protein Kinase II by Protein Phosphatases 1 and 2A

Cited by 285 publications

References 39 publications

αCaMKII autophosphorylation levels differ depending on subcellular localization

αCaMKII autophosphorylation levels differ depending on subcellular localization

CaM-kinaseII-dependent commitment to microcystin-induced apoptosis is coupled to cell budding, but not to shrinkage or chromatin hypercondensation

O-GlcNAc Transferase Is in a Functional Complex with Protein Phosphatase 1 Catalytic Subunits

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Differential Inactivation of Postsynaptic Density‐Associated and Soluble Ca²⁺/Calmodulin‐Dependent Protein Kinase II by Protein Phosphatases 1 and 2A