GPD1L links redox state to cardiac excitability by PKC-dependent phosphorylation of the sodium channel SCN5A

Carmen R. Valdivia, Kazuo Ueda, Michael J. Ackerman, Jonathan C. Makielski

Research output: Contribution to journalArticlepeer-review

84 Scopus citations


The SCN5A-encoded cardiac sodium channel underlies excitability in the heart, and dysfunction of sodium current (INa) can cause fatal ventricular arrhythmia in maladies such as long QT syndrome, Brugada syndrome (BrS), and sudden infant death syndrome (SIDS). The gene GPD1L encodes the glycerol phosphate dehydrogenase 1-like protein with homology to glycerol phosphate dehydrogenase (GPD1), but the function for this enzyme is unknown. Mutations in GPD1L have been associated with BrS and SIDS and decrease I Na through an unknown mechanism. Using a heterologous expression system, we show that GPD1L associated with SCN5A and that the BrS- and SIDS-related mutations in GPD1L caused a loss of enzymatic function resulting in glycerol-3-phosphate PKC-dependent phosphorylation of SCN5A at serine 1503 (S1503) through a GPD1L-dependent pathway. The direct phosphorylation of S1503 markedly decreased INa. These results show a function for GPD1L in cell physiology and a mechanism linking mutations in GPD1L to sudden cardiac arrest. Because the enzymatic step catalyzed by GPD1L depends upon nicotinamide adenine dinucleotide, this GPD1L pathway links the metabolic state of the cell to INa and excitability and may be important more generally in cardiac ischemia and heart failure.

Original languageEnglish (US)
Pages (from-to)H1446-H1452
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number4
StatePublished - Oct 2009


  • Cardiac arrhythmia
  • Cardiac sodium channel α-subunit
  • Cell metabolism
  • Glycerol 3-phosphate dehydrogenase 1-like
  • Ion channel
  • Protein kinase C
  • Sodium current

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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