CaMKIIδ Isoforms Differentially Affect Calcium Handling but Similarly Regulate HDAC/MEF2 Transcriptional Responses

The δB and δC splice variants of Ca2+/calmodulin-dependent protein kinase II (CaMKII), which differ by the presence of a nuclear localization sequence, are both expressed in cardiomyocytes. We used transgenic (TG) mice and CaMKII expression in cardiomyocytes to test the hypothesis that the CaMKIIδC isoform regulates cytosolic Ca2+ handling and the δB isoform, which localizes to the nucleus, regulates gene transcription. Phosphorylation of CaMKII sites on the ryanodine receptor (RyR) and on phospholamban (PLB) were increased in CaMKIIδC TG. This was associated with markedly enhanced sarcoplasmic reticulum (SR) Ca2+ spark frequency and decreased SR Ca2+ content in cardiomyocytes. None of these parameters were altered in TG mice expressing the nuclear-targeted CaMKIIδB. In contrast, cardiac expression of either CaMKIIδB or δC induced transactivation of myocyte enhancer factor 2 (MEF2) gene expression and up-regulated hypertrophic marker genes. Studies using rat ventricular cardiomyocytes confirmed that CaMKIIδB and δC both regulate MEF2-luciferase gene expression, increase histone deacetylase 4 (HDAC4) association with 14-3-3, and induce HDAC4 translocation from nucleus to cytoplasm, indicating that either isoform can stimulate HDAC4 phosphorylation. Finally, HDAC4 kinase activity was shown to be increased in cardiac homogenates from either CaMKIIδB or δC TG mice. Thus CaMKIIδ isoforms have similar effects on hypertrophic gene expression but disparate effects on Ca2+ handling, suggesting distinct roles for CaMKIIδ isoform activation in the pathogenesis of cardiac hypertrophy versus heart failure. The δB and δC splice variants of Ca2+/calmodulin-dependent protein kinase II (CaMKII), which differ by the presence of a nuclear localization sequence, are both expressed in cardiomyocytes. We used transgenic (TG) mice and CaMKII expression in cardiomyocytes to test the hypothesis that the CaMKIIδC isoform regulates cytosolic Ca2+ handling and the δB isoform, which localizes to the nucleus, regulates gene transcription. Phosphorylation of CaMKII sites on the ryanodine receptor (RyR) and on phospholamban (PLB) were increased in CaMKIIδC TG. This was associated with markedly enhanced sarcoplasmic reticulum (SR) Ca2+ spark frequency and decreased SR Ca2+ content in cardiomyocytes. None of these parameters were altered in TG mice expressing the nuclear-targeted CaMKIIδB. In contrast, cardiac expression of either CaMKIIδB or δC induced transactivation of myocyte enhancer factor 2 (MEF2) gene expression and up-regulated hypertrophic marker genes. Studies using rat ventricular cardiomyocytes confirmed that CaMKIIδB and δC both regulate MEF2-luciferase gene expression, increase histone deacetylase 4 (HDAC4) association with 14-3-3, and induce HDAC4 translocation from nucleus to cytoplasm, indicating that either isoform can stimulate HDAC4 phosphorylation. Finally, HDAC4 kinase activity was shown to be increased in cardiac homogenates from either CaMKIIδB or δC TG mice. Thus CaMKIIδ isoforms have similar effects on hypertrophic gene expression but disparate effects on Ca2+ handling, suggesting distinct roles for CaMKIIδ isoform activation in the pathogenesis of cardiac hypertrophy versus heart failure. Ca2+/calmodulin-dependent protein kinase II δ (CaMKIIδ) 4The abbreviations used are: CaMKII, Ca2+/calmodulin-dependent protein kinase II; ANF, atrial natriuretic factor; BNP, brain natriuretic peptide; dn, dominant negative; GST, glutathione S-transferase; HDAC, histone deacetylase; MEF2, myocyte enhancer factor 2;β-MHC,β-myosin heavy chain; NLS, nuclear localization sequence; NRVMs, neonatal rat ventricular myocytes; PE, phenylephrine; PLB, phospholamban; RyR2, cardiac ryanodine receptor; SK.Actin, α-skeletal actin; SR, sarcoplasmic reticulum; TG, transgenic; WT, wild type; PBS, phosphate-buffered saline; HA, hemagglutinin. is the predominant isoform of CaMKII in the heart. Splice variants differing in the presence of a nuclear localization sequence (NLS) show distinct subcellular targeting to either cytoplasmic or nuclear compartments (1Edman C.F. Schulman H. Biochim. Biophys. Acta. 1994; 1221: 89-101Crossref PubMed Scopus (159) Google Scholar, 2Srinivasan M. Edman C.F. Schulman H. J. Cell Biol. 1994; 126: 839-852Crossref PubMed Scopus (238) Google Scholar, 3Ramirez M.T. Zhao X. Schulman H. Brown J.H. J. Biol. Chem. 1997; 272: 31203-31208Abstract Full Text Full Text PDF PubMed Scopus (175) Google Scholar). The CaMKIIδB isoform contains an 11 amino acid NLS that is absent from δC. Thus CaMKII heteromers comprised predominantly of δB subunits localize to the nucleus while those with predominantly δC localize to the cytoplasm (1Edman C.F. Schulman H. Biochim. Biophys. Acta. 1994; 1221: 89-101Crossref PubMed Scopus (159) Google Scholar, 2Srinivasan M. Edman C.F. Schulman H. J. Cell Biol. 1994; 126: 839-852Crossref PubMed Scopus (238) Google Scholar, 3Ramirez M.T. Zhao X. Schulman H. Brown J.H. J. Biol. Chem. 1997; 272: 31203-31208Abstract Full Text Full Text PDF PubMed Scopus (175) Google Scholar). We recently demonstrated that both δB and δC CaMKII are activated in response to pressure overload induced by thoracic aortic banding but that expression of these isoforms is differentially regulated (4Zhang T. Maier L.S. Dalton N.D. Miyamoto S. Ross Jr., J. Bers D.M. Brown J.H. Circ. Res. 2003; 92: 912-919Crossref PubMed Scopus (479) Google Scholar). The possibility that there are discrete roles for these two isoforms in regulating Ca2+ homeostasis and gene transcription has not yet been explored. CaMKII has long been implicated as a regulator of Ca2+ homeostasis and excitation-contraction (E-C) coupling in ventricular myocytes. This enzyme has been shown to phosphorylate proteins involved in sarcoplasmic reticulum (SR) Ca2+ handling including the cardiac ryanodine receptors (RyR2) and phospholamban (PLB) (4Zhang T. Maier L.S. Dalton N.D. Miyamoto S. Ross Jr., J. Bers D.M. Brown J.H. Circ. Res. 2003; 92: 912-919Crossref PubMed Scopus (479) Google Scholar, 5Bassani R.A. Mattiazzi A. Bers D.M. Am. J. Physiol. 1995; 268: H703-H712Crossref PubMed Google Scholar, 6Hain J. Onoue H. Mayrleitner M. Fleischer S. Schindler H. J. Biol. Chem. 1995; 270: 2074-2081Abstract Full Text Full Text PDF PubMed Scopus (251) Google Scholar, 7Karczewski P. Kuschel M. Baltas L.G. Bartel S. Krause E.G. Basic Res. Cardiol. 1997; 92: 37-43Crossref PubMed Google Scholar, 8Witcher D.R. Kovacs R.J. Schulman H. Cefali D.C. Jones L.R. J. Biol. Chem. 1991; 266: 11144-11152Abstract Full Text PDF PubMed Google Scholar, 9Wehrens X.H. Lehnart S.E. Reiken S.R. Marks A.R. Circ. Res. 2004; 94: E61-E70Crossref PubMed Google Scholar, 10Maier L.S. Bers D.M. J. Mol. Cell Cardiol. 2002; 34: 919-939Abstract Full Text PDF PubMed Scopus (243) Google Scholar). Phosphorylation of the RyR2 appears to alter its channel open probability (9Wehrens X.H. Lehnart S.E. Reiken S.R. Marks A.R. Circ. Res. 2004; 94: E61-E70Crossref PubMed Google Scholar, 10Maier L.S. Bers D.M. J. Mol. Cell Cardiol. 2002; 34: 919-939Abstract Full Text PDF PubMed Scopus (243) Google Scholar, 11Marks A.R. J. Mol. Cell Cardiol. 2001; 33: 615-624Abstract Full Text PDF PubMed Scopus (156) Google Scholar) while phosphorylation of PLB by CaMKII can regulate SR Ca2+ uptake (10Maier L.S. Bers D.M. J. Mol. Cell Cardiol. 2002; 34: 919-939Abstract Full Text PDF PubMed Scopus (243) Google Scholar, 12Mattiazzi A. Mundina-Weilenmann C. Guoxiang C. Vittone L. Kranias E. Cardiovasc. Res. 2005; 68: 366-375Crossref PubMed Scopus (115) Google Scholar). Altered intracellular Ca2+ handling plays an important role in the pathogenesis of heart with in Ca2+ cardiac of has demonstrated that altered of the RyR2, to increased phosphorylation by to cardiac in heart Reiken S. T. Marks A.R. Full Text Full Text PDF PubMed Scopus Google Scholar, M. T. M. M. T. S. T. M. S. H. M. PubMed Scopus Google Scholar, X.H. Lehnart S.E. Marks A.R. Physiol. 2005; PubMed Scopus Google Scholar, M. T. M. 2005; PubMed Scopus Google Scholar). demonstrated that expression of CaMKIIδC in transgenic mice increased RyR2 phosphorylation and Ca2+ from the SR, and that these were in the of heart and (4Zhang T. Maier L.S. Dalton N.D. Miyamoto S. Ross Jr., J. Bers D.M. Brown J.H. Circ. Res. 2003; 92: 912-919Crossref PubMed Scopus (479) Google Scholar). CaMKII expression and activation in the RyR2 to the enhanced RyR2 phosphorylation and SR Ca2+ in an of heart X. Bers D.M. Circ. Res. 2005; PubMed Scopus Google Scholar). the CaMKIIδC isoform has to and these cytosolic has not been CaMKII has been implicated in the associated with of cardiac We that expression of δB CaMKII in neonatal rat ventricular atrial natriuretic factor gene expression and in enhanced activation of an gene M.T. Zhao X. Schulman H. Brown J.H. J. Biol. Chem. 1997; 272: 31203-31208Abstract Full Text Full Text PDF PubMed Scopus (175) Google Scholar). are with the that the and which CaMKIIδB can the nucleus, induce hypertrophic in cardiomyocytes in S.R. J. PubMed Scopus Google Scholar). transgenic (TG) have confirmed a role for in activation of the hypertrophic gene and of hypertrophy in mice were to cardiac hypertrophy A.R. PubMed Scopus Google Scholar) which was shown to be associated with an increase in the activity of CaMKII in A.R. Mol. PubMed Scopus Google Scholar). hypertrophy in transgenic mice that S.R. J. PubMed Scopus Google Scholar) is not a isoform in the heart is for pressure overload induced hypertrophy (1Edman C.F. Schulman H. Biochim. Biophys. Acta. 1994; 1221: 89-101Crossref PubMed Scopus (159) Google Scholar, H. J. Biol. Chem. Full Text PDF PubMed Google Scholar, L. A.R. Mol. 2003; PubMed Scopus Google Scholar). has shown that transgenic mice that the nuclear cardiac CaMKIIδB isoform by and in hypertrophic gene expression T. Schulman H. Ross Jr., J. Brown J.H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). CaMKIIδB is and in of these TG mice T. Schulman H. Ross Jr., J. Brown J.H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google as is expressed in cardiomyocytes M.T. Zhao X. Schulman H. Brown J.H. J. Biol. Chem. 1997; 272: 31203-31208Abstract Full Text Full Text PDF PubMed Scopus (175) Google Scholar). The transcription factor myocyte enhancer factor 2 (MEF2) has been to as a for hypertrophic in the L. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar, J. S. A. PubMed Scopus Google Scholar). have been shown to with and activation J. S. A. PubMed Scopus Google Scholar, C. E. J. T. J. PubMed Scopus Google Scholar, J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar) and of from in its activation J. S. A. PubMed Scopus Google Scholar, J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). was demonstrated to be a for in TG S.R. J. PubMed Scopus Google Scholar) activation was to phosphorylation and of II from there is a of the nuclear-targeted CaMKIIδB isoform to activation and hypertrophic gene expression in and in cardiomyocytes has not been explored. The of the was to there are for CaMKIIδB and CaMKIIδC isoforms in the heart. We that cytoplasmic CaMKIIδ of δC in phosphorylation and of Ca2+ handling nuclear CaMKIIδ of δB is involved in of phosphorylation and activation associated with that the δB and δC CaMKII isoforms have distinct effects on phosphorylation of proteins and Ca2+ the two isoforms and hypertrophic gene that the of CaMKII isoform activation the for of in gene expression and Ca2+ handling that cardiac hypertrophy and heart failure. mice expressing either the cytoplasmic CaMKIIδC or the nuclear CaMKIIδB in the heart were as (4Zhang T. Maier L.S. Dalton N.D. Miyamoto S. Ross Jr., J. Bers D.M. Brown J.H. Circ. Res. 2003; 92: 912-919Crossref PubMed Scopus (479) Google Scholar, T. Schulman H. Ross Jr., J. Brown J.H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). The of mice a by of the the has been C. P. 126: PubMed Google Scholar). CaMKIIδB or δC TG mice were with mice and of and CaMKIIδB or δC TG mice were used for mice used in the were of were in with for the and of and by the and and homogenates were and and as (4Zhang T. Maier L.S. Dalton N.D. Miyamoto S. Ross Jr., J. Bers D.M. Brown J.H. Circ. Res. 2003; 92: 912-919Crossref PubMed Scopus (479) Google Scholar, T. Schulman H. Ross Jr., J. Brown J.H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). The used for and were as from Marks and Ca2+ and of ventricular were for Ca2+ spark frequency and SR Ca2+ content as L.S. T. L. J. Brown J.H. Bers D.M. Circ. Res. 2003; 92: PubMed Scopus Google Scholar). ventricular were on and for The were using in phosphate-buffered and for with in were with in in 4 in PBS, and with in in for 2 were on by using and from CaMKIIδB or δC TG mice or from mice expressing the but not CaMKII were and in with were in in activity were on ventricular using a from of with to and protein and of rat ventricular were and or with as M.T. Brown J.H. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google Scholar, Brown J.H. S. A. PubMed Scopus Google Scholar). were a of 4 of a or and in were and in for to were for with gene with or CaMKII isoforms using a M.T. Brown J.H. J. Biol. Chem. 1995; 270: Full Text Full Text PDF PubMed Scopus Google Scholar). were the hypertrophic 2 to response was and were for an in activity in was and to were and the was with with were with for The was a from of were and in with an were for or for with an or an of the expressed HDAC4 was by using and was from ventricular using was using the to for the expression of hypertrophic marker was using and from and the of expression were to HDAC4 kinase activity were in ventricular homogenates as J. S. S. J. PubMed Scopus Google Scholar) with a glutathione protein of was used as a protein with a in HDAC4 to to CaMKII was used as J. S. S. J. PubMed Scopus Google Scholar). The proteins were to were with ventricular in and for 4 4 were with the were in kinase and and and were to for were and were by by and using a are as S.E. of was using was Phosphorylation of RyR2 and PLB the CaMKII in CaMKII TG cytoplasmic and nuclear CaMKII differentially regulate the phosphorylation of Ca2+ proteins in phosphorylation of RyR2 and PLB in ventricular homogenates from CaMKIIδB and δC TG mice. used in which to the of hypertrophy or heart of in mice and two expressing similar of either CaMKIIδB or The phosphorylation of the RyR2, using an to the CaMKII phosphorylation was increased in TG mice expressing the δC isoform of CaMKII In there was increase in RyR2 phosphorylation in TG mice expressing the nuclear-targeted CaMKIIδB Phosphorylation of PLB the CaMKII was increased in CaMKIIδC TG mice but not in from mice expressing nuclear-targeted CaMKIIδB This suggesting that RyR2 and PLB are not in for CaMKIIδB but are for cytosolic CaMKIIδC activity (4Zhang T. Maier L.S. Dalton N.D. Miyamoto S. Ross Jr., J. Bers D.M. Brown J.H. Circ. Res. 2003; 92: 912-919Crossref PubMed Scopus (479) Google Scholar, T. Schulman H. Ross Jr., J. Brown J.H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). SR Ca2+ and SR Ca2+ in CaMKII TG the effects of the CaMKII isoforms on RyR2 and PLB phosphorylation in in Ca2+ handling, cardiomyocytes were from CaMKIIδB and δC TG mice and Ca2+ spark frequency and SR Ca2+ content were The CaMKIIδB was confirmed to be in the nucleus using that for CaMKIIδC was shown to be in the cytoplasm of the cardiomyocytes Ca2+ spark frequency and decreased SR Ca2+ content were in cardiomyocytes from the CaMKIIδC TG as demonstrated (4Zhang T. Maier L.S. Dalton N.D. Miyamoto S. Ross Jr., J. Bers D.M. Brown J.H. Circ. Res. 2003; 92: 912-919Crossref PubMed Scopus (479) Google Scholar). The effects of nuclear-targeted CaMKII on these parameters were not show by that spark frequency and SR Ca2+ are not in expressing CaMKIIδB and which localizes to the nucleus and to increase RyR2 phosphorylation. The cytoplasmic isoform of CaMKIIδC appears to have a to alter Ca2+ handling phosphorylation of Ca2+ proteins that are to the cytosolic In of by the transcription factor is an in for and its activation is for CaMKII in the nucleus the CaMKIIδB or δC TG mice were with mice C. P. 126: PubMed Google Scholar). activation was by of and by of activity in from of WT, CaMKIIδB and CaMKIIδC TG mice the mice of which not yet increased heart to or were to that in activation were not to these from mice expressing the gene of expressing CaMKII was markedly increased with in expression of either δB or δC isoforms of CaMKII increased the activation of of ventricular were and activity as were in both the CaMKIIδB and CaMKIIδC expressing mice The of protein expression was by and not to differ in and TG Thus the effects of CaMKII on activity activation of not in that increased expression of either δB or δC isoforms of CaMKII can in In of by that can be activated by either CaMKIIδB or MEF2-luciferase were in neonatal rat ventricular MEF2-luciferase induced by the hypertrophic was in the presence or of or dominant of CaMKIIδB or δC. The activation of was enhanced by expression of either δB or δC CaMKII and by either CaMKIIδB or δC The of in activation by was by of The of to stimulate was by HDAC4 and the of by HDAC4 was by of either CaMKIIδB or δC that CaMKII activity of of in CaMKII TG that a hypertrophic gene and cardiac in both CaMKIIδB and δC TG mice of (4Zhang T. Maier L.S. Dalton N.D. Miyamoto S. Ross Jr., J. Bers D.M. Brown J.H. Circ. Res. 2003; 92: 912-919Crossref PubMed Scopus (479) Google Scholar, T. Schulman H. Ross Jr., J. Brown J.H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). The possibility that the altered gene expression was a response to in cardiac was not in these hypertrophic were induced in both to of from mice was by marker including ANF, brain natriuretic heavy and α-skeletal were shown in increased expression of these hypertrophic marker was in both CaMKIIδB and δC TG mice for the that of hypertrophic is an response to activation of by CaMKIIδB or δC. HDAC4 with and HDAC4 by has recently been to phosphorylate HDAC4 but not II J. S. S. J. PubMed Scopus Google Scholar). The phosphorylation of HDAC4 sites for the protein and the is to the HDAC4 to is a of by CaMKIIδ and is by both CaMKIIδB and δC cardiomyocytes were with CaMKIIδB or δC and of with HDAC4 was by shown in and the of associated with HDAC4 was increased and in and Thus both CaMKIIδB and δC isoforms can the association of HDAC4 with The effects of CaMKII on HDAC4 translocation were CaMKIIδB J. S. S. J. PubMed Scopus Google Scholar) and CaMKIIδC were used in these shown in is in of nuclear localization of The CaMKIIδB was in the nucleus, while the CaMKIIδC was to the cytoplasm HDAC4 was the cytoplasm with either isoform of CaMKIIδ that phosphorylation in the cytoplasm its can that in the nucleus to and nuclear and to the of gene HDAC4 in CaMKII TG was recently shown to phosphorylate HDAC4 on and J. S. S. J. PubMed Scopus Google Scholar). has not been CaMKIIδB or δC are in to phosphorylation or CaMKII expressed in in cardiomyocytes has HDAC4 kinase ventricular homogenates from CaMKIIδB or δC TG mice and were and HDAC4 kinase activity were using a the two CaMKII phosphorylation shown in HDAC4 phosphorylation was increased in homogenates from either CaMKIIδB or δC TG with was increase in kinase activity either TG and was used as was increase in phosphorylation of an HDAC4 the CaMKII the of the HDAC4 kinase in the ventricular homogenates as The CaMKII expression in the CaMKIIδC versus CaMKIIδB mice used in these on HDAC4 kinase but and from both HDAC4 kinase as a for Ca2+ in the a role in the of cardiac hypertrophy and heart failure. CaMKII is a or of subunits by or δ Schulman H. Physiol. 1995; PubMed Scopus Google Scholar, T. H. T. J. Cell Biol. 1991; PubMed Scopus (175) Google Scholar). The δ of CaMKII in the heart and there are distinct splice variants of CaMKIIδ and by the presence of a nuclear localization sequence in the (1Edman C.F. Schulman H. Biochim. Biophys. Acta. 1994; 1221: 89-101Crossref PubMed Scopus (159) Google Scholar, L.G. P. Krause 1995; PubMed Scopus Google Scholar, P. M. A. Basic Res. Cardiol. 1995; PubMed Scopus Google Scholar). The NLS δB or to the nucleus, CaMKIIδC enzyme hypothesis by the localization of these CaMKII isoforms is that distinct roles in that to hypertrophy and heart failure. In by the of CaMKIIδ in gene expression, a response implicated in and in of Ca2+ handling that to of heart failure. from a of and from both in and in to that cytoplasmic and nuclear CaMKIIδ isoforms the to induce and hypertrophic gene expression, while regulating phosphorylation of proteins and Ca2+ of HDAC4 Phosphorylation and by with which on these was that HDAC4 be and activated the nuclear the of gene Thus these to be activated by the nuclear-targeted CaMKIIδB In of MEF2-luciferase gene expression, of to HDAC, and of of HDAC4 in the cytoplasm that these can be induced by expression of either δB or δC splice variants of CaMKIIδ in cardiomyocytes. from the demonstrated that HDAC4 phosphorylation can be regulated either in the nucleus or in the of J. S. S. J. PubMed Scopus Google Scholar). This and T. C. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google activated of CaMKII that not the nucleus and to stimulate and regulate in using TG mice for HDAC4 by either CaMKII shown that a gene is and that HDAC4 kinase activity is in from TG mice expressing either CaMKIIδB or II as of cardiac hypertrophy S. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar, S. Mol. Cell Biol. 2004; PubMed Scopus Google with a of transcription in to MEF2, for response factor of can induce cardiac hypertrophy and J. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus (156) Google Scholar, X. J. P. Brown T. J. J. Am. J. Physiol. 2001; PubMed Google and kinase has been shown to by HDAC4 M. R.J. J. Biol. Chem. 2003; Full Text Full Text PDF PubMed Scopus Google Scholar). Thus activation of CaMKII regulate either or gene expression phosphorylation and of of hypertrophic are regulated by MEF2, and transcription We that there is of hypertrophic marker including ANF, BNP, and in from CaMKIIδB and CaMKIIδC TG Thus in using MEF2-luciferase gene expression, to HDAC, and HDAC4 translocation as as in transactivation of MEF2, of HDAC4 and of hypertrophic gene expression that either CaMKII isoform can regulate gene is that CaMKIIδC the nucleus as of a with CaMKIIδB and to the of gene that a of the CaMKIIδC is associated with the nuclear CaMKIIδC is in and in the nucleus is yet is the isoform for gene expression in the TG with the for cytosolic of for roles of the two CaMKII isoforms in phosphorylation both from and of the nuclear demonstrated that expression of the nuclear δB isoform of CaMKII induced gene expression in neonatal rat ventricular the cytoplasmic CaMKIIδC not M.T. Zhao X. Schulman H. Brown J.H. J. Biol. Chem. 1997; 272: 31203-31208Abstract Full Text Full Text PDF PubMed Scopus (175) Google Scholar). We recently these not and that gene expression was induced in both CaMKIIδB and δC with the on expression We that the used recently from as were those used of expression those used the expression of that of MEF2-luciferase and can be by either CaMKIIδB or of HDAC4 by II a and can be by and HDAC4 has recently been shown to have a CaMKII that is not on J. S. S. J. PubMed Scopus Google Scholar). We show that HDAC4 not kinase activity is increased in CaMKII TG with This is of CaMKII but not of or which are II that can phosphorylate and subcellular localization of II J. S. S. J. PubMed Scopus Google Scholar). phosphorylation of two sites on HDAC4 its to protein and in the in HDAC4 translocation that HDAC4 cytoplasmic response to of a In which is appears to be to the cytoplasm and with The cytosolic CaMKIIδC appears to show a of localization with HDAC4 the CaMKIIδC expressed in TG appears to be in the the of HDAC4 that CaMKII and HDAC4 a in the cytoplasm, and that have effects on gene The shown in the by which cytoplasmic CaMKII, HDAC4 in the from the can the in the as CaMKII HDAC4 in the nucleus and its nuclear the and of the cytosolic and nuclear to be the of either of HDAC4 in the be to gene of CaMKII on Phosphorylation of to with to HDAC4 phosphorylation and gene expression, that CaMKIIδC is in its to phosphorylate RyR2 and PLB and to induce in SR Ca2+ and Ca2+ We the of CaMKIIδC on phosphorylation of proteins and Ca2+ to the cytoplasmic localization of the two CaMKII isoforms in cardiomyocytes. CaMKIIδ protein expression is versus as is CaMKII activity versus in the CaMKIIδC versus the CaMKIIδB TG (4Zhang T. Maier L.S. Dalton N.D. Miyamoto S. Ross Jr., J. Bers D.M. Brown J.H. Circ. Res. 2003; 92: 912-919Crossref PubMed Scopus (479) Google Scholar, T. Schulman H. Ross Jr., J. Brown J.H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). Thus that a of CaMKII is to phosphorylate PLB and a that in the CaMKIIδB mice. in that the effects of CaMKII on phosphorylation and of proteins be using expression of CaMKIIδC in cardiomyocytes M. T. T. A. S. L. Brown J.H. Bers D.M. Maier L.S. Circ. Res. PubMed Scopus Google Scholar) in Ca2+ handling were not these cardiomyocytes were with CaMKIIδB and L. S. that the of Ca2+ by CaMKIIδC in the transgenic mice is to the to the of CaMKII In of CaMKIIδB TG mice the phosphorylation of PLB T. Schulman H. Ross Jr., J. Brown J.H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). In with the that PLB phosphorylation was not PLB phosphorylation was decreased both and CaMKII sites and these were in mice of and in that the phosphorylation be for by in activity associated with of hypertrophy and heart T. Schulman H. Ross Jr., J. Brown J.H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). The mice of for both TG the of hypertrophy or heart failure. The of in PLB phosphorylation in the CaMKIIδB TG mice with the increased PLB phosphorylation in CaMKIIδC TG mice and that PLB is as a to cytoplasmic but not to of CaMKII and in and are by which Ca2+ can be to the in the nucleus, a that has been Ca2+ or can the nucleus and nuclear Schulman H. Cell PubMed Scopus Google Scholar). possibility from of for and Ca2+ the nucleus Cell PubMed Scopus Google Scholar, 92: Full Text Full Text PDF PubMed Scopus Google Scholar) or in the nuclear (10Maier L.S. Bers D.M. J. Mol. Cell Cardiol. 2002; 34: 919-939Abstract Full Text PDF PubMed Scopus (243) Google Scholar, M. Bers D.M. J. Biol. Chem. 2005; Full Text Full Text PDF PubMed Scopus (156) Google Scholar, X. T. J. X. J. Brown J.H. Bers D.M. J. PubMed Scopus Google Scholar). nuclear Ca2+ including nuclear receptors and a role in coupling Ca2+ to in cardiomyocytes. of Ca2+ from in the nuclear an for activation of nuclear-targeted of the in Ca2+ that the cardiac is that a of cytosolic in the of the nucleus, with receptors M. Bers D.M. J. Biol. Chem. 2005; Full Text Full Text PDF PubMed Scopus (156) Google is in a for activation by Ca2+ receptors and to the of that δB and δC isoforms of CaMKII were both activated by pressure overload induced but were differentially regulated the expression of pressure overload (4Zhang T. Maier L.S. Dalton N.D. Miyamoto S. Ross Jr., J. Bers D.M. Brown J.H. Circ. Res. 2003; 92: 912-919Crossref PubMed Scopus (479) Google Scholar). The increase in the activation of the two CaMKII isoforms is with both a role in the of hypertrophy activation of genes. The activation of CaMKIIδC a by RyR2 and PLB phosphorylation and Ca2+ in cytoplasmic CaMKIIδC expression, with in Ca2+ on the to the to heart by Ca2+ and or involved in of be up-regulated J. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus (156) Google Scholar, Jr., J. Mol. Cell Cardiol. 2005; Full Text Full Text PDF PubMed Scopus Google Scholar). In the cytoplasmic CaMKIIδC to be an and to of heart failure. We for A. Marks for and M. for We the by of for with