Background:
Inherited cardiomyopathy associates with a range of phenotype, mediated by genetic and non-genetic factors. Non-inherited cardiomyopathy also displays varying progression and outcomes. Expression of cardiomyopathy genes is under the regulatory control of promoters and enhancers, and human genetic variation in promoters and enhancers may contribute to this variability.
Methods:
We superimposed epigenomic profiling from hearts and cardiomyocytes, including promoter-capture chromatin conformation information, to identify enhancers for two cardiomyopathy genes,
MYH7
and
LMNA
. Enhancer function was validated in human cardiomyocytes derived from induced pluripotent stem cells. We also conducted a genome-wide search to ascertain genomic variation in enhancers positioned to alter cardiac expression and correlated one of these variants to cardiomyopathy progression using biobank data.
Results:
Multiple enhancers were identified and validated for
LMNA
and
MYH7
, including a key enhancer that regulates the switch from
MYH6
expression to
MYH7
expression. Deletion of this enhancer resulted in a dose-dependent increase in
MYH6
and faster contractile rate in engineered heart tissues. We searched for genomic variation in enhancer sequences across the genome, with focus on nucleotide changes that create or interrupt transcription factor binding sites. rs875908 disrupts a TBX5 binding motif and maps to an enhancer region 2KB from the transcriptional start site of
MYH7
. Gene editing to remove the enhancer harboring this variant markedly reduced
MYH7
expression in human cardiomyocytes. Using biobank-derived data, rs875908 associated with longitudinal echocardiographic features with cardiomyopathy.
Conclusions:
Enhancers regulate cardiomyopathy gene expression, and genomic variation within these enhancer regions associates with cardiomyopathic progression over time. This integrated approach identified noncoding modifiers of cardiomyopathy and is applicable to other cardiac genes.