Expression and Pharmacology of Endogenous Cav Channels in SH-SY5Y Human Neuroblastoma Cells

SH-SY5Y human neuroblastoma cells provide a useful in vitro model to study the mechanisms underlying neurotransmission and nociception. These cells are derived from human sympathetic neuronal tissue and thus, express a number of the Ca v channel subtypes essential for regulation of important physiological functions, such as heart contraction and nociception, including the clinically validated pain target Ca v 2.2. We have detected mRNA transcripts for a range of endogenous expressed subtypes Ca v 1.3, Ca v 2.2 (including two Ca v 1.3, and three Ca v 2.2 splice variant isoforms) and Ca v 3.1 in SH-SY5Y cells; as well as Ca v auxiliary subunits α 2 δ 1–3 , β 1 , β 3 , β 4 , γ 1 , γ 4–5 , and γ 7 . Both high- and low-voltage activated Ca v channels generated calcium signals in SH-SY5Y cells. Pharmacological characterisation using ω-conotoxins CVID and MVIIA revealed significantly (∼ 10-fold) higher affinity at human versus rat Ca v 2.2, while GVIA, which interacts with Ca v 2.2 through a distinct pharmacophore had similar affinity for both species. CVID, GVIA and MVIIA affinity was higher for SH-SY5Y membranes vs whole cells in the binding assays and functional assays, suggesting auxiliary subunits expressed endogenously in native systems can strongly influence Ca v 2.2 channels pharmacology. These results may have implications for strategies used to identify therapeutic leads at Ca v 2.2 channels.