TY  - JOUR
JF  - Cardiovascular Research
A1  - Schobesberger, S
A1  - Wright, P
A1  - Tokar, S
A1  - Bhargava, A
A1  - Mansfield, C
A1  - Glukhov, AV
A1  - Poulet, C
A1  - Buzuk, A
A1  - Monszpart, A
A1  - Sikkel, M
A1  - Harding, SE
A1  - Nikolaev, VO
A1  - Lyon, AR
A1  - Gorelik, J
SN  - 1755-3245
UR  - https://doi.org/10.1093/cvr/cvx074
N1  - © The Author 2017. Published by Oxford University Press on behalf of the European Society of Cardiology
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
IS  - 7
VL  - 113
SP  - 770
KW  - Heart failure
KW  -  Hypertrophy
KW  -  Remodelling
KW  -  ?-Adrenoreceptor signalling
KW  -  T-tubules
KW  -  Scanning ion conductance microscopy
ID  - discovery1561216
N2  - AIMS: 
Cardiomyocyte ?2-adrenergic receptor (?2AR) cyclic adenosine monophosphate (cAMP) signalling is regulated by the receptors? subcellular location within transverse tubules (T-tubules), via interaction with structural and regulatory proteins, which form a signalosome. In chronic heart failure (HF), ?2ARs redistribute from T-tubules to the cell surface, which disrupts functional signalosomes and leads to diffuse cAMP signalling. However, the functional consequences of structural changes upon ?2AR-cAMP signalling during progression from hypertrophy to advanced HF are unknown.


METHODS AND RESULTS: 
Rat left ventricular myocytes were isolated at 4-, 8-, and 16-week post-myocardial infarction (MI), ?2ARs were stimulated either via whole-cell perfusion or locally through the nanopipette of the scanning ion conductance microscope. cAMP release was measured via a Förster Resonance Energy Transfer-based sensor Epac2-camps. Confocal imaging of di-8-ANNEPS-stained cells and immunoblotting were used to determine structural alterations. At 4-week post-MI, T-tubule regularity, density and junctophilin-2 (JPH2) expression were significantly decreased. The amplitude of local ?2AR-mediated cAMP in T-tubules was reduced and cAMP diffused throughout the cytosol instead of being locally confined. This was accompanied by partial caveolin-3 (Cav-3) dissociation from the membrane. At 8-week post-MI, the ?2AR-mediated cAMP response was observed at the T-tubules and the sarcolemma (crest). Finally, at 16-week post-MI, the whole cell ?2AR-mediated cAMP signal was depressed due to adenylate cyclase dysfunction, while overall Cav-3 levels were significantly increased and a substantial portion of Cav-3 dissociated into the cytosol. Overexpression of JPH2 in failing cells in vitro or AAV9.SERCA2a gene therapy in vivo did not improve ?2AR-mediated signal compartmentation or reduce cAMP diffusion.


CONCLUSION: Although changes in T-tubule structure and ?2AR-mediated cAMP signalling are significant even at 4-week post-MI, progression to the HF phenotype is not linear. At 8-week post-MI the loss of ?2AR-mediated cAMP is temporarily reversed. Complete disorganization of ?2AR-mediated cAMP signalling due to changes in functional receptor localization and cellular structure occurs at 16-week post-MI.
TI  - T-tubule remodelling disturbs localized ?2-adrenergic signalling in rat ventricular myocytes during the progression of heart failure
EP  - 782
AV  - public
Y1  - 2017/06//
ER  -