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- Title
Cardiac expression of the CREM repressor isoform CREM-IbΔCX in mice leads to arrhythmogenic alterations in ventricular cardiomyocytes.
- Authors
Schulte, J. S.; Fehrmann, E.; Tekook, M. A.; Kranick, D.; Fels, B.; Li, N.; Wehrens, X. H. T.; Heinick, A.; Seidl, M. D.; Schmitz, W.; Müller, F. U.
- Abstract
Chronic β-adrenergic stimulation is regarded as a pivotal step in the progression of heart failure which is associated with a high risk for arrhythmia. The cAMP-dependent transcription factors cAMP-responsive element binding protein (CREB) and cAMP-responsive element modulator (CREM) mediate transcriptional regulation in response to β-adrenergic stimulation and CREM repressor isoforms are induced after stimulation of the β-adrenoceptor. Here, we investigate whether CREM repressors contribute to the arrhythmogenic remodeling in the heart by analyzing arrhythmogenic alterations in ventricular cardiomyocytes (VCMs) from mice with transgenic expression of the CREM repressor isoform CREM-IbΔC-X (TG). Patch clamp analyses, calcium imaging, immunoblotting and realtime quantitative RT-PCR were conducted to study proarrhythmic alterations in TG VCMs vs. wild-type controls. The percentage of VCMs displaying spontaneous suprathreshold transient-like Ca2+ releases was increased in TG accompanied by an enhanced transduction rate of subthreshold Ca2+ waves into these supra-threshold events. As a likely cause we discovered enhanced NCX-mediated Ca2+ transport and NCX1 protein level in TG. An increase in INCX and decrease in Ito and its accessory channel subunit KChIP2 was associated with action potential prolongation and an increased proportion of TG VCMs showing early afterdepolarizations. Finally, ventricular extrasystoles were augmented in TG mice underlining the in vivo relevance of our findings. Transgenic expression ofCREM-IbΔC-X in mouse VCMs leads to distinct arrhythmogenic alterations. Since CREM repressors are inducible by chronic β-adrenergic stimulation our results suggest that the inhibition of CRE-dependent transcription contributes to the formation of an arrhythmogenic substrate in chronic heart disease.
- Publication
Basic Research in Cardiology, 2016, Vol 111, Issue 2, p15
- ISSN
0300-8428
- Publication type
Article
- DOI
10.1007/s00395-016-0532-y