Crucial role of nicotinic α5 subunit variants for Ca2+ fluxes in ventral midbrain neurons

Miriam Sciaccaluga, Claudia Moriconi, Katiuscia Martinello, Myriam Catalano, Isabel Bermudez, Jerry A. Stitzel, Uwe Maskos, Sergio Fucile

Research output: Contribution to journalArticle

Abstract

Neuronal nicotinic acetylcholine receptors (nAChRs) containing the α5 subunit modulate nicotine consumption, and the human CHRNA5 rs16969968 polymorphism, causing the replacement of the aspartic acid residue at position 398 with an asparagine (α5DN), has recently been associated with increased use of tobacco and higher incidence of lung cancer. We show that in ventral midbrain neurons, the α5 subunit is essential for heteromeric nAChR-induced intracellular-free Ca2+ concentration elevations and that in α5-/- mice, a class of large-amplitude nicotine-evoked currents is lost. Furthermore, the expression of the α5DN subunit is not able to restore nicotinic responses, indicating a loss of function by this subunit in native neurons. To understand how α5DN impairs heteromeric nAChR functions, we coexpressed α4, α5, or α5DN subunits with a dimeric concatemer (β2α4) in a heterologous system, to obtain nAChRs with fixed stoichiometry. Both a5(β2α4)2 and a5DN(β2α4)2 nAChRs yielded similar levels of functional expression and Ca2+ permeability, measured as fractional Ca2+ currents (8.2 ± 0.7% and 8.0 ± 1.9%, respectively), 2-fold higher than a4 (β2α4)2. Our results indicate that the loss of function of nicotinic responses observed in α5DN-expressing ventral midbrain neurons is neither due to an intrinsic inability of this subunit to form functional nAChRs nor to an altered Ca2+ permeability but likely to intracellular modulation.

Original languageEnglish
Pages (from-to)3389-3398
Number of pages10
JournalFASEB Journal
Volume29
Issue number8
DOIs
Publication statusPublished - Aug 1 2015

Fingerprint

Nicotinic Receptors
Mesencephalon
Neurons
Fluxes
Nicotine
Permeability
Tobacco
Asparagine
Tobacco Use
Polymorphism
Aspartic Acid
Stoichiometry
Lung Neoplasms
Modulation
Incidence

Keywords

  • Ca<sup>2+</sup> permeability
  • Fractional Ca<sup>2+</sup> current
  • Nicotine dependence
  • Nicotinic acetylcholine receptors

ASJC Scopus subject areas

  • Biochemistry
  • Biotechnology
  • Genetics
  • Molecular Biology

Cite this

Crucial role of nicotinic α5 subunit variants for Ca2+ fluxes in ventral midbrain neurons. / Sciaccaluga, Miriam; Moriconi, Claudia; Martinello, Katiuscia; Catalano, Myriam; Bermudez, Isabel; Stitzel, Jerry A.; Maskos, Uwe; Fucile, Sergio.

In: FASEB Journal, Vol. 29, No. 8, 01.08.2015, p. 3389-3398.

Research output: Contribution to journalArticle

Sciaccaluga, M, Moriconi, C, Martinello, K, Catalano, M, Bermudez, I, Stitzel, JA, Maskos, U & Fucile, S 2015, 'Crucial role of nicotinic α5 subunit variants for Ca2+ fluxes in ventral midbrain neurons', FASEB Journal, vol. 29, no. 8, pp. 3389-3398. https://doi.org/10.1096/fj.14-268102
Sciaccaluga M, Moriconi C, Martinello K, Catalano M, Bermudez I, Stitzel JA et al. Crucial role of nicotinic α5 subunit variants for Ca2+ fluxes in ventral midbrain neurons. FASEB Journal. 2015 Aug 1;29(8):3389-3398. https://doi.org/10.1096/fj.14-268102
Sciaccaluga, Miriam ; Moriconi, Claudia ; Martinello, Katiuscia ; Catalano, Myriam ; Bermudez, Isabel ; Stitzel, Jerry A. ; Maskos, Uwe ; Fucile, Sergio. / Crucial role of nicotinic α5 subunit variants for Ca2+ fluxes in ventral midbrain neurons. In: FASEB Journal. 2015 ; Vol. 29, No. 8. pp. 3389-3398.
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