Molecular studies on the control of the expression of the NPY-Y1 receptor gene

The cDNA that encodes for the rat NPY-Y1 receptor has been reported (Eva at al., 1990) and predicts a classical G-protein coupled receptor. This receptor has been linked to important physiological process in the nervous system (Grundemar and Hakanson, 1994). In this thesis the gene that encodes for the promoter of the rat NPY-Y1 receptor was obtained by PCR subcloning. (i) This region contains several consensus sequences for transcription factors: a "TATA-like" box, a "CAAT-like" box, an Sp1 site, an AP1 site, two CRE elements, a non-palindromic ERE and four non-palindromic GRE. (ii) This region has been attached to the reporter function, luciferase, so that the expression of this enzyme has been placed under the control of the promoter region of the NPY-Y1 receptor (pY1-LUC). (iii) The pY1-LUC has been transiently transfected into PC12 cells, a rat phaeochromocytoma cell line (Greene and Tischler, 1976), GTl-7 cells, a mouse hypothalamic cell line (Mellon et al., 1990) and RINm5f cells, a rat beta-pancreatic cell line (Poliak et al., 1993) which express constitutive levels of the NPY-Y1 receptor. It is thus possible to measure the basal transcriptional activity of this gene and study the factors which affect its transcriptional levels in these cells. (iv) Differentiation of the cells into an adrenal chromaffin-like phenotype with dexamethasone and in a neuronal-like phenotype with NGF or PACAP increased the transcriptional activity of the NPY-Y1 gene in PC 12 cells. Moreover, activation of PKA with DBC or forskolin, and activation of PKC with DH1 or PMA also increased the expression of this gene in PC12 cells. (v) The transcriptional response to NGF was dependent on trk A receptor and PKC activation but independent of ras-MAPK activation. Moreover, the effect of PACAP-38 was dependent in both PKA and PKC activation, but is also independent in ras-MAPK activation. Thus, the transcription of the NPY-Y1 receptor its under tight regulation by the glucocorticoid receptor, PKA and PKC signalling in a sympatho-adrenal model system, PC 12 cells.