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Updated: Jun 13, 2025
Analysis of Tubular Membrane Networks in Cardiac Myocytes from Atria and Ventricles
Published on: October 15, 2014
Chronic Activation of Tubulin Tyrosination Improves Heart Function
Niels Pietsch1,2, Christina Y Chen3,4, Svenja Kupsch5,6
1Department of Experimental Pharmacology and Toxicology (N.P., B.G., E.K., G.M., S.S., L.C.), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Insights
Chronic activation of tubulin tyrosine ligase (TTL) improved heart function in hypertrophic cardiomyopathy (HCM) models. This approach targets the nonsarcomeric cytoskeleton, offering a new therapeutic strategy for HCM and other heart diseases.
Area of Science:
- Cardiovascular Biology
- Cellular Biology
- Genetics
Background:
- Hypertrophic cardiomyopathy (HCM) is a genetic heart disorder linked to sarcomeric gene variants, causing left ventricular hypertrophy and diastolic dysfunction.
- Elevated microtubule detyrosination (dTyr-MT) is observed in heart failure, suggesting a role for the microtubule network.
- Previous studies showed acute reduction of dTyr-MT improved contractility and reduced stiffness in human failing cardiomyocytes.
Purpose of the Study:
- To investigate the impact of chronic tubulin tyrosination on hypertrophic cardiomyopathy (HCM).
- To assess the effects of tubulin tyrosine ligase (TTL) activation in an HCM mouse model, human HCM cardiomyocytes, and human engineered heart tissues (EHTs).
Main Methods:
- Adeno-associated virus serotype 9-mediated TTL transfer was used in neonatal wild-type rodents, 3-week-old HCM mice, and HCM human induced pluripotent stem cell-derived cardiomyocytes.
- Experiments were conducted on SVBP-deficient human engineered heart tissues (EHTs) to compare with TTL-deficient and wild-type EHTs.
Main Results:
- Chronic TTL treatment dose-dependently reduced dTyr-MT and improved contractility in cardiomyocytes without altering cytosolic calcium.
- In HCM mice, TTL improved diastolic filling, compliance, cardiac output, and stroke volume by reducing myocardial dTyr-MT.
- TTL normalized cell area in human HCM cardiomyocytes and activated tubulin/cytoskeleton transcription without significant proteome impact in mice.
- SVBP-deficient EHTs showed reduced dTyr-MT, increased force, and faster relaxation compared to TTL-deficient and wild-type EHTs.
Conclusions:
- This study presents the first proof of concept for chronic tubulin tyrosination as a therapeutic strategy in HCM.
- Targeting the nonsarcomeric cytoskeleton via tubulin tyrosination shows promise for improving heart function in HCM.
- The findings suggest a potential new avenue for treating heart diseases by modulating the microtubule network.
Background:
Hypertrophic cardiomyopathy (HCM) is the most common cardiac genetic disorder caused by sarcomeric gene variants and associated with left ventricular hypertrophy and diastolic dysfunction. The role of the microtubule network has recently gained interest with the findings that microtubule detyrosination (dTyr-MT) is markedly elevated in heart failure. Acute reduction of dTyr-MT by inhibition of the detyrosinase (VASH [vasohibin]/SVBP [small VASH-binding protein] complex) or activation of the tyrosinase (TTL [tubulin tyrosine ligase]) markedly improved contractility and reduced stiffness in human failing cardiomyocytes and thus posed a new perspective for HCM treatment. In this study, we tested the impact of chronic tubulin tyrosination in an HCM mouse model (Mybpc3 knock-in), in human HCM cardiomyocytes, and in SVBP-deficient human engineered heart tissues (EHTs).
Methods:
Adeno-associated virus serotype 9-mediated TTL transfer was applied in neonatal wild-type rodents, in 3-week-old knock-in mice, and in HCM human induced pluripotent stem cell-derived cardiomyocytes.
Results:
We show (1) TTL for 6 weeks dose dependently reduced dTyr-MT and improved contractility without affecting cytosolic calcium transients in wild-type cardiomyocytes; (2) TTL for 12 weeks reduced the abundance of dTyr-MT in the myocardium, improved diastolic filling, compliance, cardiac output, and stroke volume in knock-in mice; (3) TTL for 10 days normalized cell area in HCM human induced pluripotent stem cell-derived cardiomyocytes; (4) TTL overexpression activated transcription of tubulins and other cytoskeleton components but did not significantly impact the proteome in knock-in mice; (5) SVBP-deficient EHTs exhibited reduced dTyr-MT levels, higher force, and faster relaxation than TTL-deficient and wild-type EHTs. RNA sequencing and mass spectrometry analysis revealed distinct enrichment of cardiomyocyte components and pathways in SVBP-deficient versus TTL-deficient EHTs.
Conclusions:
This study provides the first proof of concept that chronic activation of tubulin tyrosination in HCM mice and in human EHTs improves heart function and holds promise for targeting the nonsarcomeric cytoskeleton in heart disease.
