Biology subjects

Kornienko, J.

Publications and source records attributed to Kornienko, J..

3 recordsLinked to original sources

bioRxiv2026

Multimodal phenotyping defines variant-to-function maps for RBM20 in dilated cardiomyopathy

Multiplex assays of variant effects have linked thousands of genotypes to fitness effects, yet we lack profound understanding of how variants impact molecular phenotypes. Here, we introduce a deep mutational scanning framework that quantifies disease-determining molecular phenotypes in human cells, allowing readouts of protein localization and splicing regulatory function at scale. Applied to the dilated cardiomyopathy (DCM)-associated protein RBM20, we profiled [~]4,300 amino acid substitutions across disease-linked protein domains. Complemented by structure-function investigations of RBM20 bound to its nuclear import receptor TNPO3, we discover new variant hotspots affecting protein function. Finally, we systematically probed nuclear relocalization to identify variants that may be amenable to this therapeutic strategy. Together, we create comprehensive variant-to-function maps that predict variant impact, enhance clinical interpretation, and stratify RBM20-mediated DCM into mechanistically distinct therapeutic classes.

genomics↗

bioRxiv2025

CAMK2D causes heart failure in RBM20 cardiomyopathy

Although heart disease can arise from different etiologies, current treatment is not tailored to the different underlying causes but is rather a one-size-fits-all approach. Importantly, not all patients benefit from this treatment regimen, which means the number needed to treat is very high. Moreover, this makes clinical trials large and costly, limiting clinical translation. Thus, there is a high medical need to develop a first etiology-specific therapy. Mutations in RBM20, a splicing factor that targets multiple pivotal cardiac genes including TTN and CAMK2D, cause a clinically aggressive form of dilated cardiomyopathy (DCM) with a high risk of malignant ventricular arrhythmias. Here, we hypothesized that CAMK2D is the heart disease-causing target of RBM20. We crossed Camk2d- to Rbm20-deficient mice and found that double knockout (DKO) mice were protected from heart failure and sudden cardiac death. Phosphorylation of multiple CAMK2D targets was increased in Rbm20-deficient mouse hearts, which was reverted in DKO hearts, confirming that CAMK2D is not only misspliced but also overactivated. AAV9-mediated re-expression of single CAMK2D splice variants in DKO mice reintroduced cardiac dysfunction irrespective of the splice variant, unmasking that overactivation rather than missplicing underlies the detrimental phenotype. To test whether heart failure could pharmacologically be reversed, we treated heterozygous Rbm20-R636Q knock-in (KI) mice with hesperadin, a potent CAMK2 inhibitor, which rescued both cardiac function and ventricular geometry. These data demonstrate that overactivation of CAMK2D underlies heart failure in RBM20 cardiomyopathy. Pharmacological inhibition of CAMK2D could therefore become the first cause-directed DCM therapy.

molecular biology↗

bioRxiv2022

Striated muscle-specific base editing enables correction of mutations causing dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is the second most common cause for heart failure with no cure except a high-risk heart transplantation. Approximately 30% of DCM patients harbor heritable mutations which are amenable to CRISPR-based gene therapy1. However, challenges related to delivery of the editing complex and off-target concerns hamper the broad applicability of CRISPR agents in the heart2. We employed a combination of the viral gene transfer vector AAVMYO with superior targeting specificity of heart muscle tissue3 and CRISPR base editors to repair patient mutations in the cardiac splice factor Rbm20, which cause aggressive and arrhythmogenic DCM4. Using optimized conditions, we could improve splice defects in human iPSC-derived cardiomyocytes (iPSC-CMs) and repair >70% of cardiomyocytes in two Rbm20 knock-in mouse models that we generated to serve as an in vivo platform of our editing strategy. Treatment of juvenile mice restored the localization defect of RBM20 in 75% of cells and splicing of RBM20 targets including TTN. Three months after injection, cardiac dilation and ejection fraction reached wildtype levels. Single-nuclei RNA sequencing (snRNA-seq) uncovered restoration of the transcriptional profile across all major cardiac cell types and whole-genome sequencing (WGS) revealed no evidence for aberrant off-target editing. Our study highlights the potential of base editors combined with AAVMYO to achieve gene repair for treatment of hereditary cardiac diseases.

genetics↗