K2P channels carry background (or leak) potassium current and contribute to the maintenance of cellular resting membrane potential. Based on their role in regulating neuronal excitability, K2Ps represent a promising target class for the treatment of pain. To support the development of novel K2P-based analgesics, we aimed to identify suitable cells for more physiologically relevant assay development and screening. This work will also add important target validation in the role of K2Ps in pathophysiology.

Gene expression of K2Ps and other known neuronal targets was investigated by RT-qPCR in cultures of 1) ND7/23 and SH-SY5Y cell lines (including differentiation into a neuronal phenotype), 2) human iPSC-derived sensory neurons, and 3) cryopreserved dissociated primary cells from rodent dorsal root ganglia (DRG) or trigeminal ganglia (TG). The two cell lines were determined to be suboptimal for studies, both as surrogates for neurons and in terms of their K2P expression profile. K2P gene expression was found to be upregulated in human iPSC-derived sensory neurons, compared to hiPSCs.

K2P gene expression was consistently detected in primary rodent cell cultures, which included post-mitotic DRG and TG neurons in the physiologically relevant environment of supporting non-neuronal cells. The neuron-specific contribution to this was further interrogated by promoting neuronal health and survival using exogenous nerve growth factor, inhibiting non-neuronal cell proliferation using anti-mitotic agents, or enriching the neuronal population by magnetic-activated cell sorting (MACS).

Primary DRG neuron cultures were subsequently used for RNA in situ hybridisation assay development. Visualising K2P mRNA localisation in different sensory neuron subsets will aid functional studies in these cells, with the goal of identifying compounds with more predictable analgesic effects in vivo.