Activation and Regulation of TRPV1 : Studies in Recombinant Human Neuroblastoma TRPV1-SHSY5Y Cells

Sammanfattning: TRPV1 is a transmembrane non-selective cation channel with preference for Ca2+. The receptor is primarily localised on dorsal root ganglion neurons and is activated by numerous endogenous and exogenous potentially irritating ligands eliciting pain. The TRPV1 expression and activity are regulated by several neurotrophic agents and inflammatory mediators via activation of phosphorylation cascades.In this thesis a stably TRPV1-expressing cell clone of the human neuroblastoma cell line SHSY5Y was established with the purpose to study regulation of TRPV1 through a straightforward and reproducible approach.In paper I it is reported that the neurotrophic factors insulin, and IGF-1 up-regulate TRPV1 in the TRPV1-SHSY5Y cells. Additionally, the involved signalling pathways are suggested. This is of interest because both TRPV1 activity and expression is altered in diabetic patients with painful neuropathies, and so is insulin and IGF-1 signalling.Results from paper II show that the neuronally differentiating morphogen retinoic acid (RA) increases TRPV1 protein levels and TRPV1-mediated Ca2+ influxes. Furthermore, the basal Ca2+ level is increased after RA treatment in TRPV1-SHSY5Y cells but not in native SHSY5Y cells. The TRPV1-SHSY5Y cells also develop into a more mature neuronal phenotype than the native SHSY5Y cells after six days of RA-induced differentiation. Hence, TRPV1 might be involved in neurogenesis.In paper III-IV it is concluded that the TRPV1-SHSY5Y cells can be used in a semi-high throughput screening (HTS)-mode to adress TRPV1-mediated Ca2+ influxes. In this assay it is shown that anionic linear aliphatic surfactants might be potent ligands of TRPV1. As a concluding remark, the TRPV1–SHSY5Y cells can be utilised to assess activation and regulation of TRPV1 in an easy-to-use and robust model system.