Dilated cardiomyopathy mutations in thin-filament regulatory proteins reduce contractility, suppress systolic Ca 2+ , and activate NFAT and Akt signaling.

Autor: Robinson P; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.; British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom., Sparrow AJ; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.; British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom., Patel S; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.; British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom., Malinowska M; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.; British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom., Reilly SN; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.; British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom., Zhang YH; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.; British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom., Casadei B; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.; British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom., Watkins H; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.; British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom., Redwood C; Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.; British Heart Foundation, Centre of Research Excellence, University of Oxford, Oxford, United Kingdom.
Jazyk: angličtina
Zdroj: American journal of physiology. Heart and circulatory physiology [Am J Physiol Heart Circ Physiol] 2020 Aug 01; Vol. 319 (2), pp. H306-H319. Date of Electronic Publication: 2020 Jul 03.
DOI: 10.1152/ajpheart.00272.2020
Abstrakt: Dilated cardiomyopathy (DCM) is clinically characterized by dilated ventricular cavities and reduced ejection fraction, leading to heart failure and increased thromboembolic risk. Mutations in thin-filament regulatory proteins can cause DCM and have been shown in vitro to reduce contractility and myofilament Ca 2+ -affinity. In this work we have studied the functional consequences of mutations in cardiac troponin T (R131W), cardiac troponin I (K36Q) and α-tropomyosin (E40K) using adenovirally transduced isolated guinea pig left ventricular cardiomyocytes. We find significantly reduced fractional shortening with reduced systolic Ca 2+ . Contraction and Ca 2+ reuptake times were slowed, which contrast with some findings in murine models of myofilament Ca 2+ desensitization. We also observe increased sarcoplasmic reticulum (SR) Ca 2+ load and smaller fractional SR Ca 2+ release. This corresponds to a reduction in SR Ca 2+ -ATPase activity and increase in sodium-calcium exchanger activity. We also observe dephosphorylation and nuclear translocation of the nuclear factor of activated T cells (NFAT), with concordant RAC-α-serine/threonine protein kinase (Akt) phosphorylation but no change to extracellular signal-regulated kinase activation in chronically paced cardiomyocytes expressing DCM mutations. These changes in Ca 2+ handling and signaling are common to all three mutations, indicating an analogous pathway of disease pathogenesis in thin-filament sarcomeric DCM. Previous work has shown that changes to myofilament Ca 2+ sensitivity caused by DCM mutations are qualitatively opposite from hypertrophic cardiomyopathy (HCM) mutations in the same genes. However, we find several common pathways such as increased relaxation times and NFAT activation that are also hallmarks of HCM. This suggests more complex intracellular signaling underpinning DCM, driven by the primary mutation. NEW & NOTEWORTHY Dilated cardiomyopathy (DCM) is a frequently occurring cardiac disorder with a degree of genetic inheritance. We have found that DCM mutations in proteins that regulate the contractile machinery cause alterations to contraction, calcium-handling, and some new signaling pathways that provide stimuli for disease development. We have used guinea pig cells that recapitulate human calcium-handling and introduced the mutations using adenovirus gene transduction to look at the initial triggers of disease before remodeling.
Databáze: MEDLINE
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