MicroRNA-208a is a regulator of cardiac hypertrophy and conduction in mice
Thomas E. Callis, … , Craig H. Selzman, Da-Zhi Wang
Thomas E. Callis, … , Craig H. Selzman, Da-Zhi Wang
Published August 10, 2009
Citation Information: J Clin Invest. 2009;119(9):2772-2786. https://doi.org/10.1172/JCI36154.
View: Text | PDF
Research Article Cardiology

MicroRNA-208a is a regulator of cardiac hypertrophy and conduction in mice

Abstract

MicroRNAs (miRNAs) are a class of small noncoding RNAs that have gained status as important regulators of gene expression. Here, we investigated the function and molecular mechanisms of the miR-208 family of miRNAs in adult mouse heart physiology. We found that miR-208a, which is encoded within an intron of α-cardiac muscle myosin heavy chain gene (Myh6), was actually a member of a miRNA family that also included miR-208b, which was determined to be encoded within an intron of β-cardiac muscle myosin heavy chain gene (Myh7). These miRNAs were differentially expressed in the mouse heart, paralleling the expression of their host genes. Transgenic overexpression of miR-208a in the heart was sufficient to induce hypertrophic growth in mice, which resulted in pronounced repression of the miR-208 regulatory targets thyroid hormone–associated protein 1 and myostatin, 2 negative regulators of muscle growth and hypertrophy. Studies of the miR-208a Tg mice indicated that miR-208a expression was sufficient to induce arrhythmias. Furthermore, analysis of mice lacking miR-208a indicated that miR-208a was required for proper cardiac conduction and expression of the cardiac transcription factors homeodomain-only protein and GATA4 and the gap junction protein connexin 40. Together, our studies uncover what we believe are novel miRNA-dependent mechanisms that modulate cardiac hypertrophy and electrical conduction.

Authors

Thomas E. Callis, Kumar Pandya, Hee Young Seok, Ru-Hang Tang, Mariko Tatsuguchi, Zhan-Peng Huang, Jian-Fu Chen, Zhongliang Deng, Bronwyn Gunn, Janelle Shumate, Monte S. Willis, Craig H. Selzman, Da-Zhi Wang

×

Figure 5

Expression of βMHC is decreased in Mir208a–/– hearts.

Options: View larger image (or click on image) Download as PowerPoint
Expression of βMHC is decreased in Mir208a–/– hearts. (A) Strategy t...
(A) Strategy to delete miR-208a from intron 31 of the Myh6 gene by homologous recombination. The miR-208a coding sequence (green box) was replaced by a neomycin selection cassette flanked by loxP sites (red triangles). The selection cassette was excised from the germline by mating with mice that ubiquitously expressed Cre recombinase, thus creating a mutant allele that contained a single loxP sequence in place of miR-208a. Genotyping PCR primers and 5′ probes are indicated. NdeI, restriction enzyme site; P1, primer binding site 1. (B) The occurrence of the intended recombination event in mouse ES cells was confirmed by PCR and Southern blot analyses. (C) The increased length of the mutant allele was the basis for a PCR-based genotyping strategy. (D) Genotypes of progeny from mating miR-208a mice were born at a Mendelian ratio (n = 128). (E) Northern blot analysis for miR-208a expression in hearts from wild-type (Mir208a+/+), Mir208a+/–, and Mir208a–/– mice. *P < 0.01. (F) Heart weight to body weight ratios of 4-month-old wild-type and Mir208a–/– mice (n = 25/genotype). (G) Transcripts for αMHC, βMHC, and ANF were detected by real-time PCR in hearts from wild-type and Mir208a–/– mice (n = 5/genotype). Values are presented as the fold change in mean expression ± SEM. *P < 0.01. (H) Western blot analysis of total MHC and βMHC protein levels in hearts from wild-type and Mir208a–/– mice. **P < 0.05. (I) Northern blot analysis of miRNA expression using hearts from wild-type, Mir208a+/–, and Mir208a–/– mice.