Characterisation of Nav types endogenously expressed in human SH-SY5Y neuroblastoma cells

The human neuroblastoma cell line SH-SY5Y is a potentially useful model for the identification and characterisation of Na-v modulators, but little is known about the pharmacology of their endogenously expressed Na(v)s. The aim of this study was to determine the expression of endogenous Na-v alpha and beta subunits in SH-SY5Y cells using PCR and immunohistochemical approaches, and pharmacologically characterise the Na-v isoforms endogenously expressed in this cell line using electrophysiological and fluorescence approaches. SH-SY5Y human neuroblastoma cells were found to endogenously express several Na-v isoforms including Na(v)1.2 and Na(v)1.7. Activation of endogenously expressed Na(v)s with veratridine or the scorpion toxin 001 caused membrane depolarisation and subsequent Ca2+ influx through voltage-gated L- and N-type calcium channels, allowing Na-v activation to be detected with membrane potential and fluorescent Ca-2 dyes. mu-Conotoxin TIIIA and ProTxII identified Na(v)1.2 and Na(v)1.7 as the major contributors of this response. The Na(v)1.7-selective scorpion toxin OD1 in combination with veratridine produced a Na(v)1.7-selective response, confirming that endogenously expressed human Na(v)1.7 in SH-SY5Y cells is functional and can be synergistically activated, providing a new assay format for ligand screening. Crown Copyright (C) 2012 Published by Elsevier Inc. All rights reserved.