Neuronal calcium sensor 1 and phosphatidylinositol 4-OH kinase β interact in neuronal cells and are translocated to membranes during nucleotide-evoked exocytosis

Elena Taverna, Maura Francolini, Andreas Jeromin, Sabine Hilfiker, John Roder, Patrizia Rosa

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

Neuronal calcium sensor 1 (NCS-1) belongs to a family of EF-hand calcium-binding proteins and is mainly expressed in neurons and neuroendocrine cells, where it causes facilitation of neurotransmitter release through unknown mechanisms. The yeast homologue of NCS-1 has been demonstrated to interact with and regulate the activity of yeast phosphatidylinositol 4-OH kinase β (PI4Kβ). However, in neurons and neurosecretory cells NCS-1 has not unequivocally been shown to interact with PI4Kβ. Here we have compared the subcellular distribution of NCS-1 and PI4Kβ and investigated whether they are capable of forming complexes. In neurons, both proteins are widely distributed and are present in perikarya and, to a lesser extent, in nerve terminals. A consistent portion of NCS-1 and PIK4β is cytosolic, whereas a portion of both proteins appears to be associated with the membranes of the endoplasmic reticulum and the Golgi complex. Very small amounts of NCS-1 and PI4Kβ are present in synaptic vesicles. Our results further demonstrate that in neurosecretory cells, endogenous NCS-1 and PIK4β interact to form a complex that can be immunoisolated from membrane as well as from cytosolic fractions. Moreover, both proteins can be recruited to membranes when cells are treated with nucleotide receptor agonists known to increase polyphosphoinositide turnover and concomitantly induce exocytosis of secretory vesicles. Finally, in PC12 cells overexpressing NCS-1, the amount of PI4Kβ associated with the membranes is increased concomitantly with the increased levels of NCS-1 detected in the same membrane fractions. Together, these findings demonstrate that mammalian NCS-1 and PI4Kβ interact under physiological conditions, which suggest a possible role for NCS-1 in the translocation of PI4Kβ to target membranes.

Original languageEnglish (US)
Pages (from-to)3909-3922
Number of pages14
JournalJournal of cell science
Volume115
Issue number20
DOIs
StatePublished - Oct 15 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Cell Biology

Keywords

  • Calcium-binding protein
  • Membrane traffic
  • Neuronal calcium sensor 1
  • Phosphatidylinosinol 4-OH kinase
  • Polyphosphoinositides

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