Calcium-dependent Nedd4-2 upregulation mediates degradation of the cardiac sodium channel Nav1.5: implications for heart failure.
Acta Physiol (Oxf)
; 221(1): 44-58, 2017 Sep.
Article
in En
| MEDLINE
| ID: mdl-28296171
ABSTRACT
AIM:
Reductions in voltage-gated sodium channel (Nav1.5) function/expression provide a slowed-conduction substrate for cardiac arrhythmias. Nedd4-2, which is activated by calcium, post-translationally modulates Nav1.5. We aim to investigate whether elevated intracellular calcium ([Ca2+ ]i ) reduces Nav1.5 through Nedd4-2 and its role in heart failure (HF).METHODS:
Using a combination of biochemical, electrophysiological, cellular and in vivo methods, we tested the effect and mechanism of calcium on Nedd4-2 and in turn Nav1.5.RESULTS:
Increased [Ca2+ ]i , following 24-h ionomycin treatment, decreased sodium current (INa ) density and Nav1.5 protein without altering its mRNA in both neonatal rat cardiomyocytes (NRCMs) and HEK 293 cells stably expressing Nav1.5. The calcium chelator BAPTA-AM restored the reduced Nav1.5 and INa in NRCMs pre-treated by ionomycin. Nav1.5 was decreased by Nedd4-2 transfection and further decreased by 6-h ionomycin treatment. These effects were not observed in cells transfected with the catalytically inactive mutant, Nedd4-2 C801S, or with Y1977A-Nav1.5 mutant containing the impaired Nedd4-2 binding motif. Furthermore, elevated [Ca2+ ]i increased Nedd4-2, the interaction between Nedd4-2 and Nav1.5, and Nav1.5 ubiquitination. Nav1.5 protein is decreased, whereas Nedd4-2 is increased in volume-overload HF rat hearts, with increased co-localization of Nav1.5 with ubiquitin or Nedd4-2 as indicated by immunofluorescence staining. BAPTA-AM rescued the reduced Nav1.5 protein, INa and increased Nedd4-2 in hypertrophied NRCMs induced by isoproterenol or angiotensin II.CONCLUSION:
Calcium-mediated increases in Nedd4-2 downregulate Nav1.5 by ubiquitination. Nav1.5 is downregulated and co-localizes with Nedd4-2 and ubiquitin in failing rat heart. These data suggest a role of Nedd4-2 in Nav1.5 downregulation in HF.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Calcium
/
NAV1.5 Voltage-Gated Sodium Channel
/
Nedd4 Ubiquitin Protein Ligases
/
Heart Failure
Limits:
Animals
/
Humans
Language:
En
Journal:
Acta Physiol (Oxf)
Year:
2017
Document type:
Article