Tubulin expression and modification in heart failure with preserved ejection fraction (HFpEF)

Diastolic dysfunction in heart failure with preserved ejection fraction (HFpEF) is characterised by increased left ventricular stiffness and impaired active relaxation. Underpinning pathomechanisms are incompletely understood. Cardiac hypertrophy and end stage heart disease are associated with alterations in the cardiac microtubule (MT) network. Increased amounts and modifications of alpha-tubulin associate with myocardial stiffness. MT alterations in HFpEF have not been analysed yet. Using ZSF1 obese rats (O-ZSF1), a validated HFpEF model, we characterised MT-modifying enzymes, quantity and tyrosination/detyrosination pattern of alpha-tubulin at 20 and 32 weeks of age. In the left ventricle of O-ZSF1, alpha-tubulin concentration (20 weeks: 1.5-fold, p = 0.019; 32 weeks: 1.7-fold, p = 0.042) and detyrosination levels (20 weeks: 1.4-fold, p = 0.013; 32 weeks: 1.3-fold, p = 0.074) were increased compared to lean ZSF1 rats. Tyrosination/alpha-tubulin ratio was lower in O-ZSF1 (20 weeks: 0.8-fold, p = 0.020; 32 weeks: 0.7-fold, p = 0.052). Expression of alpha-tubulin modifying enzymes was comparable. These results reveal new alterations in the left ventricle in HFpEF that are detectable during early (20 weeks) and late (32 weeks) progression. We suppose that these alterations contribute to diastolic dysfunction in HFpEF and that reestablishment of MT homeostasis might represent a new target for pharmacological interventions.