Apical phosphatidylserine externalization in auditory hair cells

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8 Scopus citations


In hair cells of the inner ear, phosphatidylserine (PS), detected with fluorescent annexin V labeling, was rapidly exposed on the external leaflet of apical plasma membranes upon dissection of the organ of Corti. PS externalization was unchanged by caspase inhibition, suggesting that externalization did not portend apoptosis or necrosis. Consistent with that conclusion, mitochondrial membrane potential and hair-cell nuclear structure remained normal during externalization. PS externalization was triggered by forskolin, which raises cAMP, and blocked by inhibitors of adenylyl cyclase. Blocking Na+ influx by inhibiting the mechanoelectrical transduction channels and P2X ATP channels also inhibited external PS externalization. Diminished PS externalization was also seen in cells exposed to LY 294002, which blocks membrane recycling in hair cells by inhibiting phosphatidylinositol 3-kinase. These results indicate that PS exposure on the external leaflet, presumably requiring vesicular transport, results from elevation of intracellular cAMP, which can be triggered by Na+ entry into hair cells.

Original languageEnglish (US)
Pages (from-to)16-27
Number of pages12
JournalMolecular Membrane Biology
Issue number1
StatePublished - Jan 2007


  • Annexin V
  • Hair cells
  • Membrane cycling
  • cAMP

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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