Sodium channel heterologous expression in mammalian cells and the role of the endogenous beta1-subunits.
Sodium currents in cell lines transfected with the sole alpha-subunit, or constitutively expressing sodium channels, have an inactivation that is always prevalently mono-exponential. Differently, expression of alpha-subunit in Xenopus oocytes exerts slow inactivating currents with biphasic decay, while simultaneous co-transfection of alpha and beta1 restores a mono-exponential (normal) inactivation. A hypothesis for such differences is that an endogenous presence of beta1 or beta1-alternative splicing, beta1A, in cells could account for the normal inactivation. To test this hypothesis and to evaluate the role for the beta1A, we inhibited the expression of beta1/beta1A by antisense oligonucleotides on Nav1.4-transfected human embryonic cell line 293 (HEK) cells. Reduction of beta1/beta1A produces no significant functional effects in Nav1.4-HEK. This result invalidates the hypothesis that the lack of slow-mode in cell lines is simply due to a constitutive expression of beta1/beta1A.
Moran
Oscar
O
Istituto di Biofisica - Sezione di Genova, CNR, Via De Marini, 10, I-16149, Genova, Italy. moran@icb.ge.cnr.it
Conti
Franco
F
Tammaro
Paolo
P
D017398:Alternative Splicing; D002460:Cell Line; D004594:Electrophysiology; D006801:Humans; D007150:Immunohistochemistry; D016376:Oligonucleotides, Antisense; D015222:Sodium Channels / Q000235:genetics* / Q000502:physiology*
D016376:Oligonucleotides, Antisense; D015222:Sodium Channels