[R01] Gene therapy for FLNC haploinsufficiency cardiomyopathy

Ente: National Heart Lung and Blood Institute

Scadenza: 2030-05-31

Importo max: 795.900 EUR

Paese: US

Descrizione

PROJECT SUMMARY Filamin-C (FLNC) is a large, actin-binding cytoskeletal protein essential for maintaining cardiomyocyte architecture, mechanotransduction, membrane stability, and cytoskeleton–extracellular matrix coupling. FLNC haploinsufficiency, caused by nonsense, frameshift, or splice-site mutations, is strongly associated with inherited dilated and arrhythmogenic cardiomyopathies. These conditions are characterized by early-onset systolic dysfunction, a high risk of malignant arrhythmias, and sudden cardiac death, often occurring before any measurable decline in ejection fraction. Current therapies, including standard heart failure medications and implantable cardioverter-defibrillators, relieve symptoms or reduce the risk of arrhythmias but do not restore FLNC protein levels and thus fail to halt disease progression. Gene replacement therapy offers a promising, mutation-agnostic strategy to address the underlying cause of FLNC haploinsufficiency. However, the full- length FLNC cDNA (~8.2 kb) far exceeds the packaging capacity of adeno-associated virus (AAV) vectors (~4.7 kb), making traditional single-vector delivery unfeasible. Technologies like split-intein and StitchR can reconstitute large transgenes from multiple AAVs, yet each has technical limitations. StitchR is currently limited to joining only two fragments, whereas split-inteins may introduce non-native amino acids that may compromise protein function. Furthermore, neither platform alone can effectively deliver full-length FLNC using just two AAVs with specificity for cardiomyocytes. To address these challenges, we engineered a truncated version of FLNC, termed miniFLNC (~5.7 kb), by deleting the Ig11-Ig19 subdomain. Importantly, homozygous miniFLNC mice display normal cardiac structure and function, indicating that this shorter version is sufficient for cardiac development and maintenance of adult cardiac homeostasis. Both full-length FLNC and miniFLNC were successfully reconstituted in vitro using split-intein and/or StitchR systems. MyoAAV vectors enabled robust and targeted delivery to cardiomyocytes in vivo. In prior work, we showed that cardiac-specific FLNC knockout (icKO) mice develop rapidly progressive dilated cardiomyopathy. We now present new data demonstrating that heterozygous FLNC haploinsufficient (Flnc+/–) mice develop late-onset cardiac dysfunction that mirrors the progression of human disease. In pilot rescue experiments, triple-AAV delivery of full-length FLNC via split-intein prevented cardiac dysfunction in icKO mice, supporting the feasibility and therapeutic potential of this platform. Based on these findings, we hypothesize that restoring FLNC expression, either through full-length or miniFLNC, can prevent and reverse cardiomyopathy in FLNC-deficient models. Aim 1 will investigate whether full-length FLNC, reconstituted from three AAVs via split-intein, can rescue cardiac function in both icKO and Flnc+/– mice. Aim 2 will evaluate whether miniFLNC, recons Istituzione: UNIVERSITY OF CALIFORNIA, SAN DIEGO PI: Ju Chen Progetto: 1R01HL187977-01

Settori: National Heart Lung and Blood Institute

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