Cooperative regulation of neurotensin content in PC12 pheochromocytoma cell cultures: effects of nerve growth factor, dexamethasone, and activators of adenylate cyclase

Abstract

Nerve growth factor, dexamethasone, and forskolin or cholera toxin (CT) act cooperatively to increase the content of neurotensin (NT) in PC12 pheochromocytoma cells. Relatively small increases in NT content occur in the presence of NGF alone or dexamethasone alone, but not of forskolin or CT alone. Increases of 10- to 100-fold occur in the presence of NGF plus dexamethasone or NGF plus forskolin, and up to 600-fold increases occur in the presence of all three agents. These increases are extremely stable and persist for at least 2 weeks after removal of dexamethasone or forskolin. The complex regulation of NT stores in PC12 cells might reflect mechanisms that regulate NT content of normal chromaffin cells and/or neurons during development or in adult life. A small amount of stored NT is released in response to stimulation with 52 mM K+. This release is blocked in the presence of 2 mM Co2+, suggesting that it occurs via Ca2+-mediated exocytosis.

Molecular Characterization and Differential Gene Induction of the Neuroendocrine‐Specific Genes Neurotensin, Neurotensin Receptor, PC1, PC2, and 7B2 in the Human Ocular Ciliary Epithelium

“…These studies suggest strongly that NT is not derived from autonomic sources (i.e., adrenergic system) in this ocular tissue. on cultured cihiary epithelial cells by NGF, forskolin, or dexamethasone is consistent with similar responses elicited in other neuroendocrine cell lines, including the pheochromocytoma PC12 cell line (Tischler et al 1986), hypothalamic cultures (Scarceriaux et al, 1995), and the medullothyroid carcinoma rMTC 6-23 cell line (Zeytinoglu et al, 1980). These findings are also in agreement with the presence of inducible cisregulatory consensus sequences with homology to glucocorticoid response elements and cyclic AMP response elements in the structure of the NT gene (Kislaukis and Dobner, 1990).…”

“…A great deal of information has been accumulated on the induction of NT mRNA expression in neuroendocrine cell lines, including the rat medullary thyroid carcinoma (rMTC), the rat pheochromocytoma (PC12), and human carcinoid BON cells (Tischler et al, 1986;Kislauskis and Dobner, 1990;Evers et al, 1995;Scarcériaux et al, 1995). Semiquantitative RT- in the human CB and human ciliary NPE cell line, ODM-2.…”

Mimicry and Inhibition of Nerve Growth Factor Effects: Interactions of Staurosporine, Forskolin, and K252a in PC12 Cells and Normal Rat Chromaffin Cells In Vitro

“…Forskolin or other agents that increase intracellular CAMP levels are known to act cooperatively with NGF to produce several changes in PC 12 cells. These include acceleration of the early stages of neurite outgrowth (Gunning et al,198 I), increased cell size (Tischler et al, 1987), altered glycolipid profiles (Schwarting et al, 19901, and increased expression of the neurotensin gene (Tischler et al, 1986;Dobner et al, 1988). In the present investigation, we have shown that forskolin also acts cooperatively with NGF to partially "rescue" neurite outgrowth from the inhibitory effects of K252a.…”

“…In some instances, NGF acts cooperatively with other substances to modulate cellular function and differentiation. Cyclic AMP (CAMP), for example, has been shown to interact with NGF in regulation of neurite outgrowth (Gunning et al, 1981), cell size (Tischler et al, 1987), glycolipid content (Schwarting et al, 1990, and neuropeptide synthesis (Tischler et al, 1986). Despite the importance of NGF in neurobiology, the mechanisms by which it acts alone or in combination with other agents remain unknown.…”

Characterization of Promoter Elements Required for Cell-Specific Expression of the Neurotensin/Neuromedin N Gene in a Human Endocrine Cell Line

“…The NT/N gene is not detectably expressed in untreated PC12 cells, and little or no increase in expression is observed in cells treated with single agents. In contrast, NT/N gene expression and NT peptide production are induced several hundredfold in response to combined treatment with nerve growth factor (NGF), dexamethasone, lithium, and the adenylate cyclase activator forskolin (23,50,76). Transfection experiments have demonstrated that all of the cis-regulatory elements required for NT/N induction in PC12 cells are contained in the proximal 200 bp of 5Ј flanking sequences of the rat NT/N gene and include a consensus AP-1 site, two near-consensus cyclic AMP response elements (CREs), and a near-consensus glucocorticoid response element (GRE) (50).…”