INDUCTION OF THE NEUROTENSIN (NT) GENE IN PC12 CELLS GIVES RISE TO NTPRECURSOR (SIMILAR-TO-88-PERCENT), NT(3-13)-LIKE PEPTIDE (SIMILAR-TO-10-PERCENT), AND NT (SIMILAR-TO-2-PERCENT)

Neurotensin (NT) is coexpressed with catecholamines in sympathetic neu rons and adrenal chromaffin cells. A pheochromocytoma PC12 cell line c an also be induced to express the NT gene and produce immunoreactive N T. In the present study, NT mRNA was quantified under various hormonal conditions and NT precursor synthesis rates were determined by pulse labeling and immunoprecipitation. In addition, NT precursor and NT-rel ated products were measured using RIA and were characterized using HPL C and Sephadex chromatography. Neurotensin mRNA, NT precursor synthesi s, and NT precursor/product levels were correlated. Surprisingly, NT a ppeared to be a minor product, both in cells and media: NT precursor ( approximately 88%), NT(3-13)-like peptide (approximately 10%), and NT (approximately 2%). Neurotensin added to cultures was not converted to NT(3-13). Treatment of cells with 60 mM KCl or various secretagogues induced Ca2+-dependent release of NT precursor, NT(3-13), and NT in pr oportion to their cellular contents. These results suggest a) that NT precursor processing in induced PC12 cells was much slower than NT pre cursor synthesis, b) that NT(3-13) was a major product and NT a minor one, and c) that NT precursor and its products were stored within secr etory vesicles.