PACAP and NGF regulate common and distinct traits of the sympathoadrenal lineage: effects on electrical properties, gene markers and transcription factors in differentiating PC12 cells

Abstract

To determine the possible role of pituitary adenylate cyclase-activating polypeptide (PACAP) in the development of the sympathoadrenal cell lineage, we have examined the effects of this neurotrophic peptide, in comparison to nerve growth factor (NGF), on the morphology, electrophysiological properties, expression of neuronal and neuroendocrine marker genes, and activity of transcription factors during differentiation of sympathoadrenal-derived cells, using the rat pheochromocytoma PC12 cell model. Both PACAP and NGF elicited rapid neurite outgrowth, which was accompanied by induction of cell excitability and the development of both sodium and calcium currents. Concurrently, PACAP and NGF increased the expression of a marker of synaptic vesicles. By contrast, PACAP, but not NGF, regulated the expression of different constituents of neuroendocrine large dense core vesicles in PC12 cells. Furthermore, PACAP and NGF differentially regulated the expression of mammalian achaete-scute homologue and paired homeobox 2b genes, transcription factors instrumental for sympathoadrenal development. To compare downstream effectors activated by PACAP and NGF, we studied the effects of these factors on the binding activity of consensus 12-O-tetradecanoylphorbol-13-acetate- and cAMP-responsive elements to nuclear extracts of differentiating PC12 cells. We found that both PACAP and NGF markedly increase the binding activity of these cis-regulatory sequences and that PACAP preferentially recruits activator protein-1-like transcription factors to these elements. Taken together, these results show that PACAP and NGF exert common as well as different effects on neuronal and neuroendocrine traits in differentiating PC12 cells, strongly suggesting that these two trophic factors could play complementary roles in the development of the sympathoadrenal cell lineage.

Expression of trophic amidated peptides and their receptors in benign and malignant pheochromocytomas: high expression of adrenomedullin RDC1 receptor and implication in tumoral cell survival

“…Accordingly, PAC1-R has been shown to mediate the effect of PACAP on catecholamine secretion in normal and tumoral sympathetic neurons (Taupenot et al 1998, Ghzili et al 2008. In addition, the prodifferentiating effects of PACAP are mediated through PAC1-R (Grumolato et al 2003b). Therefore, PACAP and its PACAP-preferring receptor PAC1-R are probably involved in the pathophysiology of pheochromocytoma.…”

Nerve growth factor as a paradigm of neurotrophins related to Alzheimer's disease

“…It has been reported that NGF can regulate membrane excitability (Rudy et al, 1987;Toledo-Aral et al, 1995;Levine et al, 1995;Lesser et al, 1999;Grumolato et al, 2003) but its possible role as neuromodulator of brain synaptic plasticity has been debated for a long time. Although NGF perfusion in hippocampal slices (Tancredi et al, 1993) has been reported to block the long-term potentiation (LTP) appearance, other papers have shown no NGF effects on hippocampal and visual cortex plasticity (Khang and Schuman, 1995;Figurov et al, 1996;Akaneya et al, 1997) Moreover, local TrkA activation in primary visual cortex (Pizzorusso et al, 1999) and in vivo NGF injection into the lateral ventricles (Maffei et al, 1992;Lodovichi et al, 2000) counteract the ocular dominance distribution of visual cortical neurons in monocularly deprivated rats.…”

Secretin induces neurite outgrowth of PC12 through cAMP-mitogen-activated protein kinase pathway

“…Stimulation with differentiating factors, including nerve growth factor (NGF), and the subsequent activation of its receptor, TrkA, were demonstrated to initiate a variety of signaling events which led to the cessation of growth, the acquirement of electrical excitability, the expression of neuron-specific marker proteins, and the extension of neurites (Hagag et al, 1986;Leoni et al, 1999;Grumolato et al, 2003). Neurite extension induced by different stimuli was determined to be a distinctive aspect of neuronal differentiation (Bouron et al, 1999).…”