β-Adrenergic Stimulation Induces Histone Deacetylase 5 (HDAC5) Nuclear Accumulation in Cardiomyocytes by B55α-PP2A-Mediated Dephosphorylation.
BACKGROUND
Class IIa histone deacetylase (HDAC) isoforms such as HDAC5 are critical signal-responsive repressors of maladaptive cardiomyocyte hypertrophy, through nuclear interactions with transcription factors including myocyte enhancer factor-2. β-Adrenoceptor (β-AR) stimulation, a signal of fundamental importance in regulating cardiac function, has been proposed to induce both phosphorylation-independent nuclear export and phosphorylation-dependent nuclear accumulation of cardiomyocyte HDAC5. The relative importance of phosphorylation at Ser259/Ser498 versus Ser279 in HDAC5 regulation is also controversial. We aimed to determine the impact of β-AR stimulation on the phosphorylation, localization, and function of cardiomyocyte HDAC5 and delineate underlying molecular mechanisms.


RESULTS
A novel 3-dimensional confocal microscopy method that objectively quantifies the whole-cell nuclear/cytoplasmic distribution of green fluorescent protein tagged HDAC5 revealed the β-AR agonist isoproterenol to induce β1-AR-mediated and protein kinase A-dependent HDAC5 nuclear accumulation in adult rat cardiomyocytes, which was accompanied by dephosphorylation at Ser259/279/498. Mutation of Ser259/Ser498 to Ala promoted HDAC5 nuclear accumulation and myocyte enhancer factor-2 inhibition, whereas Ser279 ablation had no such effect and did not block isoproterenol-induced nuclear accumulation. Inhibition of the Ser/Thr phosphatase PP2A blocked isoproterenol-induced HDAC5 dephosphorylation. Co-immunoprecipitation revealed a specific interaction of HDAC5 with the PP2A targeting subunit B55α, as well as catalytic and scaffolding subunits, which increased >3-fold with isoproterenol. Knockdown of B55α in neonatal cardiomyocytes attenuated isoproterenol-induced HDAC5 dephosphorylation.


CONCLUSIONS
β-AR stimulation induces HDAC5 nuclear accumulation in cardiomyocytes by a mechanism that is protein kinase A-dependent but requires B55α-PP2A-mediated dephosphorylation of Ser259/Ser498 rather than protein kinase A-mediated phosphorylation of Ser279.
Cardiovascular Division, King's College London British Heart Foundation Centre of Research Excellence, The Rayne Institute, St Thomas' Hospital, London, United Kingdom.|Baker Heart and Diabetes Institute, Melbourne, Australia.
Kate L
KL
Weeks
Cardiovascular Division, King's College London British Heart Foundation Centre of Research Excellence, The Rayne Institute, St Thomas' Hospital, London, United Kingdom.
Antonella
A
Ranieri
Cardiovascular Division, King's College London British Heart Foundation Centre of Research Excellence, The Rayne Institute, St Thomas' Hospital, London, United Kingdom.
Agnieszka
A
Karaś
Baker Heart and Diabetes Institute, Melbourne, Australia.
Bianca C
BC
Bernardo
Cardiovascular Division, King's College London British Heart Foundation Centre of Research Excellence, The Rayne Institute, St Thomas' Hospital, London, United Kingdom.
Alexandra S
AS
Ashcroft
Cardiovascular Division, King's College London British Heart Foundation Centre of Research Excellence, The Rayne Institute, St Thomas' Hospital, London, United Kingdom.
Chris
C
Molenaar
Baker Heart and Diabetes Institute, Melbourne, Australia.
Julie R
JR
McMullen
Cardiovascular Division, King's College London British Heart Foundation Centre of Research Excellence, The Rayne Institute, St Thomas' Hospital, London, United Kingdom metin.avkiran@kcl.ac.uk.
Metin
M
Avkiran
D021581:Active Transport, Cell Nucleus; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects* / Q000201:enzymology; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D006655:Histone Deacetylases / Q000235:genetics / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009154:Mutation; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000201:enzymology; D010766:Phosphorylation; D011485:Protein Binding; D054648:Protein Phosphatase 2 / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D018342:Receptors, Adrenergic, beta-1 / Q000187:drug effects* / Q000378:metabolism; D012694:Serine; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection
C547789:Adrb1 protein, rat; D000318:Adrenergic beta-Agonists; D018342:Receptors, Adrenergic, beta-1; D012694:Serine; D017868:Cyclic AMP-Dependent Protein Kinases; C582184:Ppp2r2a protein, rat; D054648:Protein Phosphatase 2; C498619:Hdac5 protein, rat; D006655:Histone Deacetylases; D007545:Isoproterenol
B55α; PP2A; adrenergic stimulation; confocal imaging; histone deacetylase 5; hypertrophy/remodeling; microscopy; phosphatase; phosphorylation; three dimensional; β‐adrenergic signaling