Precise genome editing of RBM20 pathogenic mutations may salvage dilated cardiomyopathy

Gene therapy has the potential to cure familial cardiomyopathy, but it is necessary to improve the efficiency of gene editing and avoid deviation from the target gene editing
.

RNA binding motif protein 20 (RBM20) mutations are a common cause
of familial dilated cardiomyopathy (DCM).
Many RBM20 mutations are clustered within an arginine/serine-rich (RS-rich) domain responsible for mediating nuclear localization
.
These mutations lead to RBM20 mislocalization, the formation of abnormal ribonucleoprotein (RNP) particles in the cytoplasm of cardiomyocytes, and abnormal selective splicing of cardiac genes, leading to dilated cardiomyopathy
.

Nishiyama and colleagues from the University of Texas Southwestern Medical Center used an advanced, more precise adenine base editing (ABE) and primer editing (PE) approach to correct pathogenic mutations
in RNA-binding motif protein 20 (RBM20).
In vitro experiments have shown that in human induced pluripotent stem cells, ABE corrects the p.
R634Q mutation of RBM20 with 92% A-to-G editing efficiency, while PE corrects the p.
R636S mutation
of RBM20 with 40% A-to-C editing efficiency.
The corrected iPS cell-derived cardiomyocytes exhibited normal selective splicing, showed normal myoganglion structure, and restored normal RBM20 nuclear localization, eliminating abnormal RNP granule formation
.

To assess ABE's potential for the treatment of dilated cardiomyopathy, the researchers also constructed Rbm20R636Q mutant mice
.
Homozygous (R636Q/R636Q) mice exhibited severe cardiac dysfunction, heart failure, and premature death
.
Systemic delivery of ABE components containing ABEmax-VRQR-SpCas9 and uniguide RNA to these mice by adeno-associated virus serotype 9 showed that gene-editing treatment mice evaluated by echocardiogram restored cardiac function and extended lifespan
.
RNA sequencing analysis showed that ABE correction saved cardiac transcription profiles
of R636Q/R636Q mice compared to abnormal gene expression in untreated R636Q/R636Q mice.
These findings demonstrate the potential
to precisely correct genetic mutations as a promising treatment for DCM.

The findings suggest that precise correction of gene mutations using precise gene editing methods (single-gene diseases) may be a promising approach
for treating dilated cardiomyopathy.
The article is published in
a new issue of Science.