Increased tyrosine phosphorylation and novel cis-acting element mediate activation of the fibroblast growth factor-2 (FGF-2) gene by nicotinic acetylcholine receptor. New mechanism for trans-synaptic regulation of cellular development and plasticity.
FGF-2, a mitogenic/neurotrophic protein, controls the development and plasticity of many types of neural cells. In neural crest-derived adrenal pheochromatocytes, induction of FGF-2 coincides with the establishment of functional innervation and is reproduced in vitro by stimulating acetylcholine receptors (AChR). The mechanisms by which AChR activate the FGF-2 gene were examined in cultured bovine adrenal medullary chromaffin (BAMC) cells in which AChR induce expression and nuclear accumulation of growth-promoting FGF-2 and FGF-2 receptors. Carbachol or nicotine increased expression of transfected FGF-2 gene promoter-luciferase constructs and were more potent than the muscarinic agonist ABMCB. Deletion analysis has identified a unique -555/-512 bp element that confers AChR stimulation and basal activity to the downstream FGF-2 promoter, and a separate protein kinase C/cAMP-responsive sequence (-625/-555 bp). Stimulation of AChR increased in vitro formation of protein complexes with the AChR-responsive element which were not displaced by target oligonucleotides for common trans-activators. Southwestern analysis identified 50-55, 125, 140 and 170 kDa proteins that interact with the AChR-responsive element in a manner stimulated by AChR. Nicotine increased tyrosine phosphorylation of cytoplasmic and nuclear proteins, including 50-55 kDa promoter-binding factors. Activation of the FGF-2 promoter was reduced by genistein. Thus, nicotinic AChR activate the FGF-2 gene via a new signaling mechanism separate from the cAMP/PKC pathways. It utilizes tyrosine phosphorylation and interaction of trans-activating factors with a novel cis-acting element. It offers a new pathway through which trans-synaptic signals may control neural development and plasticity.
Moffett
J
J
Laboratory of Molecular Neurobiology, Barrow Neurological Institute, 350 West Thomas Road, Phoenix, AZ 85013, USA.
Kratz
E
E
Stachowiak
M K
MK
D020121:5' Untranslated Regions / Q000502:physiology*; D000311:Adrenal Glands / Q000166:cytology; D000818:Animals; D002417:Cattle; D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D019439:Chromaffin Cells; D000242:Cyclic AMP / Q000502:physiology; D016222:Fibroblast Growth Factor 2 / Q000235:genetics*; D009473:Neuronal Plasticity / Q000235:genetics*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000502:physiology; D011485:Protein Binding / Q000235:genetics; D011493:Protein Kinase C / Q000502:physiology; D011978:Receptors, Nicotinic / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D015533:Transcriptional Activation; D014443:Tyrosine / Q000378:metabolism*
D020121:5' Untranslated Regions; D011978:Receptors, Nicotinic; D016222:Fibroblast Growth Factor 2; D014443:Tyrosine; D000242:Cyclic AMP; D011493:Protein Kinase C