Nuclear Ca2+/calmodulin-dependent protein kinase II in the murine heart.
Ca(2+) signaling through CaMKII is critical in regulating myocyte function with regard to excitation-contraction-relaxation cycles and excitation-transcription coupling. To investigate the role of nuclear CaMKII in cardiac function, transgenic mice were designed and generated to target the expression of a CaMKII inhibitory peptide, AIP (KKALRRQEAVDAL), to the nucleus. The transgenic construct consists of the murine alpha-myosin heavy chain promoter followed by the expression unit containing nucleotides encoding a four repeat concatemer of AIP (AIP(4)) and a nuclear localization signal (NLS). Western blot and immunohistochemical analyses demonstrate that AIP(4) is expressed only in the nucleus of cardiac myocytes of the transgenic mice (NLS-AIP(4)). The function of cytoplasmic CaMKII is not affected by the expression of AIP(4) in the nucleus. Inhibition of nuclear CaMKII activity resulted in reduced translocation of HDAC5 from nucleus to cytoplasm in NLS-AIP(4) mouse hearts. Loss of nuclear CaMKII activity causes NLS-AIP(4) mice to have smaller hearts than their nontransgenic littermates. Transcription factors including CREB and NFkappaB are not regulated by cardiac nuclear CaMKII. With physiological stresses such as pregnancy or aging (8 months), NLS-AIP(4) mice develop hypertrophy symptoms including enlarged atria, systemic edema, sedentariness, and morbidity. RT-PCR analyses revealed that the hypertrophic marker genes, such as ANF and beta-myosin heavy chain, were upregulated in pregnancy stressed mice. Our results suggest that absence of adequate Ca2+signaling through nuclear CaMKII regulated pathways leads to development of cardiac disease.
Li
Bailing
B
Department of Genome Science, University of Cincinnati, Genome Research Institute, 2180 E. Galbraith Rd., Cincinnati, OH 45237-0505, USA.
Dedman
John R
JR
Kaetzel
Marcia A
MA
D000595:Amino Acid Sequence; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000235:genetics; D020013:Calcium Signaling; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000032:analysis / Q000037:antagonists & inhibitors / Q000502:physiology*; D006332:Cardiomegaly / Q000235:genetics*; D002467:Cell Nucleus / Q000201:enzymology; D005819:Genetic Markers; D006321:Heart / Q000033:anatomy & histology*; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009206:Myocardium / Q000201:enzymology*; D018995:Myosin Heavy Chains / Q000235:genetics; D019913:Nuclear Localization Signals / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D009929:Organ Size / Q000235:genetics; D010455:Peptides / Q000494:pharmacology; D010766:Phosphorylation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D024723:Ventricular Myosins / Q000235:genetics; D000099211:Phospholamban
D009320:Atrial Natriuretic Factor; D002135:Calcium-Binding Proteins; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D005819:Genetic Markers; D018995:Myosin Heavy Chains; D019913:Nuclear Localization Signals; D010455:Peptides; D024723:Ventricular Myosins; D000099211:Phospholamban