Functional analysis of the cell-specific enhancer in the human proopiomelanocortin gene by beta-galactosidase histochemical staining

Genomic cloning and promoter analysis of the mouse 105-kDa heat shock protein (HSP105) gene

The 105-kDa heat shock protein (HSP105) is a member of the high-molecular-mass heat shock protein family. We have isolated and characterized the mouse HSP105 gene including about 1.2 kb of the 5'-flanking region. The mouse HSP105 gene spans about 22 kb, consisting of 18 exons separated by 17 introns. Southern blotting analysis revealed the existence of a single copy of HSP105. Primer extension analysis revealed that the transcription initiation site was located 165 bp upstream of the ATG translation initiation codon. The 5'-promoter region of the HSP105 gene contained a TATA box, a CAAT box, an inverted CAAT box, and two GC boxes. Two heat shock element (HSE) sequences were found as four nGAAn repeats at nt -64 and nt -128. Promoter analysis using deletion derivatives revealed that a minimal region which contained the two consensus HSE sequences was active in response to heat shock and also for constitutive expression of the gene.

Analysis of proopiomelanocortin gene transcription mechanisms in bronchial tumour cells

The ectopic ACTH syndrome results from the transcription of the proopiomelanocortin (POMC) gene in non pituitary tumors. To determine its mechanisms, we examined in the human bronchial carcinoma cell line DMS-79 transacting factors binding to the human POMC gene promoter. Three binding sites were identified in the proximal promoter and proteins were studied by gel-shift assays. One of them is a binding site for Nur77/Nurr1 proteins in corticotroph cells but is bound in DMS-79 cells by factor(s) distinct from these proteins. The remaining two binding sites bound yet unidentified proteins and were both functionally active in DMS-79 cells. We also showed that DMS-79 cells lacked a factor required for tissue-restricted POMC gene expression in corticotroph cells. Altogether, our results indicate that POMC gene expression in DMS-79 cells is achieved without several of the corticotroph factors and provide a preliminary characterization of some factors involved in this process. They also reveal that DMS-79 cells are deficient in proteins involved in the regulation by cAMP and glucocorticoids.

Vasoactive intestinal peptide gene expression in the rat pheochromocytoma cell line PC12

Vasoactive intestinal peptide (VIP) gene expression was analyzed in PC12 cells. VIP mRNA was detected in PC12 cells treated with VIP or forskolin whereas no VIP mRNA was detected in the untreated cells. The induction of the VIP mRNA was enhanced by the simultaneous treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA). PC12 cells stimulated with forskolin plus TPA released immunoreactive VIP. Sephadex G-50 column chromatography revealed that the immunoreactive VIP secreted from PC12 cells is comprised of multiple forms, one of which was indistinguishable from the authentic VIP. PC12 cells supported an efficient transcription from the human VIP gene promoter in a cell-specific as well as cAMP-dependent manner. These results definitely demonstrated the expression of the VIP gene in PC12 cells. VIP biosynthesis may be positively regulated by VIP in an autocrine fashion in PC12 cells.