The endosomal trafficking regulator LITAF controls the cardiac Nav1.5 channel via the ubiquitin ligase NEDD4-2

Turan, N.N., Moshal, K.S., Roder, K., Baggett, B.C., Kabakov, A.Y., Dhakal, S., Teramoto, R., Chiang, D.Y., Zhong, M., Xie, A., Lu, Y., Dudley, S.C., MacRae, C.A., Karma, A., Koren, G.
The Journal of biological chemistry   295(52): 18148-18159 (Journal)
Registered Authors
MacRae, Calum A.
Action potential duration, Computer modelling, E3 ubiquitin ligase, LITAF, NEDD4-2, Nav1.5, cardiomyocyte, sodium channel, ubiquitin, zebrafish
MeSH Terms
  • Action Potentials
  • Animals
  • Endosomes/metabolism*
  • Genome-Wide Association Study
  • Humans
  • Myocytes, Cardiac/cytology
  • Myocytes, Cardiac/metabolism*
  • NAV1.5 Voltage-Gated Sodium Channel/genetics
  • NAV1.5 Voltage-Gated Sodium Channel/metabolism*
  • Nedd4 Ubiquitin Protein Ligases/genetics
  • Nedd4 Ubiquitin Protein Ligases/metabolism*
  • Nuclear Proteins/genetics
  • Nuclear Proteins/metabolism*
  • Protein Binding
  • Protein Transport
  • Rabbits
  • Transcription Factors/genetics
  • Transcription Factors/metabolism*
  • Ubiquitin/metabolism*
  • Ubiquitination
  • Zebrafish
33093176 Full text @ J. Biol. Chem.
The QT interval is a recording of cardiac electrical activity. Previous genome-wide association studies (GWAS) identified genetic variants that modify the QT interval upstream of LITAF (lipopolysaccharide-induced tumor necrosis factor-alpha factor), a protein encoding a regulator of endosomal trafficking. However, it was not clear how LITAF might impact cardiac excitation. We investigated the effect of LITAF on the voltage-gated sodium channel Nav1.5, which is critical for cardiac depolarization. We show that overexpressed LITAF resulted in a significant increase in the density of Nav1.5-generated voltage-gated sodium current INa and Nav1.5 surface protein levels in rabbit cardiomyocytes and in HEK cells stably expressing Nav1.5. Proximity ligation assays showed co-localization of endogenous LITAF and Nav1.5 in cardiomyocytes, while co-immunoprecipitations confirmed they are in the same complex when overexpressed in HEK cells. In vitro data suggests LITAF interacts with the ubiquitin ligase NEDD4-2, a regulator of Nav1.5. LITAF overexpression downregulated NEDD4-2 in cardiomyocytes and HEK cells. In HEK cells, LITAF increased ubiquitination and proteasomal degradation of co-expressed NEDD4-2 and significantly blunted the negative effect of NEDD4-2 on INa We conclude that LITAF controls cardiac excitability by promoting degradation of NEDD4-2, which is essential for removal of surface Nav1.5. LITAF-knockout zebrafish showed increased variation in and a non-significant 15% prolongation of action potential duration (APD). Computer simulations using a rabbit-cardiomyocyte model demonstrated that changes in Ca2+ and Na+ homeostasis are responsible for the surprisingly modest APD shortening. These computational data thus corroborate findings from several GWAS that associated LITAF with QT interval variation.
Genes / Markers
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Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Engineered Foreign Genes