Loss of H3K4 methylation destabilizes gene expression patterns and physiological functions in adult murine cardiomyocytes
Adam B. Stein, … , José Jalife, Gregory R. Dressler
Adam B. Stein, … , José Jalife, Gregory R. Dressler
Published June 6, 2011
Citation Information: J Clin Invest. 2011;121(7):2641-2650. https://doi.org/10.1172/JCI44641.
View: Text | PDF
Research Article Cardiology

Loss of H3K4 methylation destabilizes gene expression patterns and physiological functions in adult murine cardiomyocytes

Abstract

Histone H3 lysine 4 (H3K4me) methyltransferases and their cofactors are essential for embryonic development and the establishment of gene expression patterns in a cell-specific and heritable manner. However, the importance of such epigenetic marks in maintaining gene expression in adults and in initiating human disease is unclear. Here, we addressed this question using a mouse model in which we could inducibly ablate PAX interacting (with transcription-activation domain) protein 1 (PTIP), a key component of the H3K4me complex, in cardiac cells. Reducing H3K4me3 marks in differentiated cardiomyocytes was sufficient to alter gene expression profiles. One gene regulated by H3K4me3 was Kv channel-interacting protein 2 (Kcnip2), which regulates a cardiac repolarization current that is downregulated in heart failure and functions in arrhythmogenesis. This regulation led to a decreased sodium current and action potential upstroke velocity and significantly prolonged action potential duration (APD). The prolonged APD augmented intracellular calcium and in vivo systolic heart function. Treatment with isoproterenol and caffeine in this mouse model resulted in the generation of premature ventricular beats, a harbinger of lethal ventricular arrhythmias. These results suggest that the maintenance of H3K4me3 marks is necessary for the stability of a transcriptional program in differentiated cells and point to an essential function for H3K4me3 epigenetic marks in cellular homeostasis.

Authors

Adam B. Stein, Thomas A. Jones, Todd J. Herron, Sanjeevkumar R. Patel, Sharlene M. Day, Sami F. Noujaim, Michelle L. Milstein, Matthew Klos, Philip B. Furspan, José Jalife, Gregory R. Dressler

×

Figure 1

Cardiac-specific PTIP deletion affects H3K4me in mice.

Options: View larger image (or click on image) Download as PowerPoint
Cardiac-specific PTIP deletion affects H3K4me in mice. (A) PTIP protein ...
(A) PTIP protein expression (140 kDa) was markedly decreased in the PTIP– mice injected with tamoxifen as compared with that in the vehicle-injected PTIP– and tamoxifen-injected PTIP+ mice. LV tissue was harvested 30 days after tamoxifen or vehicle injection, and immunoblotting was performed using chicken anti-PTIP (anti-PTIP) normalized to mouse anti–β-tubulin. (B) PTIP– (n = 3) and PTIP+ mice (n = 3/group) were injected with tamoxifen at 8 weeks of age. Thirty days later, LV tissue was harvested, mRNA was isolated, and qPCR was performed for PTIP and normalized to GAPDH using TaqMan primers. Data are mean ± SEM. *P < 0.05 versus PTIP–. (C) Eight-week-old PTIP– (n = 5) and PTIP+ (n = 3) mice were injected with tamoxifen. Eight months later immunoblotting for H3K4me3 and histone H3 (top) was performed from whole heart chromatin. Immunoblot data were quantified by normalizing H3K4me3 levels to H3 (bottom). Data are mean ± SEM. (D) Whole heart tissue from PTIP+ mice was harvested and prepped for chromatin. IP was performed on 20 μg chromatin using chicken anti-PTIP and chicken IgY (control). IP samples were then denatured in SDS, loaded into a 6% SDS gel, and probed with chicken anti-PTIP and rabbit anti-RbbP5 (Bethyl). In the sample immunoprecipitated with chicken anti-PTIP (right lane), a 140-kDa band, consistent with PTIP, and a 70-kDa band, consistent with RbBP5, were detected. These bands were not detected in the sample immunoprecipitated with chicken IgY (middle lane).