From transcription profile to expression:: The signaling repertoire of the SK-N-MC neuroepithelioma cell-line

SK-N-MC neuroepithelioma cells are routinely cultured and widely used as a model system in biochemical and pharmacological experiments. To clarify the gene expression patterns of SK-N-MC cells with respect to G protein-coupled receptors and signaling network components, we describe in this report the transcription profile of the cell line. Following the traditional pathway from genome to proteome, selected examples are further examined at the level of protein expression and by functional assays. cRNA targets derived from total RNA extracts were hybridized to Affymetrix Human Genome U133A GeneChip arrays, and the data were analyzed and grouped according to functional aspects. Results obtained for neuropeptide Y (NPY) Y-1, Y-5, and orexin Ox(1) receptors were confirmed by RT-PCR. It is surprising that we found the presence of both NPY receptor subtypes and the absence of the orexin receptor at the mRNA level. Receptor-binding experiments confirmed NPY binding of the Y-1 receptor in the nanomolar range but gave no evidence for high expression levels of Y-5 receptor subtypes on the cell surface. Protein expression was assayed with immunoblots by using antibodies directed against selected Galpha protein subunits. The presence of at least Galpha(s), Galpha(i3), and Galpha(i2) subunits was indicated.