Regulation of sympathetic neuron differentiation by endogenous nerve growth factor and neurotrophin-3.
Nerve growth factor (NGF) and neurotrophin-3 (NT3) play distinctive roles in sympathetic axon growth and target field innervation and are required for sympathetic neuron survival in vivo. To ascertain if these neurotrophins selectively regulate the expression of genes that determine the functional characteristics of differentiated sympathetic neurons, we measured the mRNA levels for several such genes in the superior cervical ganglion of NGF(-/-), NT3(-/-) and wild type mouse embryos at a stage before excessive neuronal loss occurs in the absence of these neurotrophins. Despite the extensively documented ability of NGF to regulate the noradrenergic phenotype of sympathetic neurons, we found that tyrosine hydroxylase (TH) and dopamine beta hydroxylase (DbetaH) mRNA levels were normal in NGF(-/-) embryos, but significantly reduced in NT3(-/-) embryos. In contrast, the beta2 nicotinic acetylcholine receptor and PACAP receptor 1 mRNA levels were normal in NT3(-/-) embryos, but significantly reduced in NGF(-/-) embryos. Studies of mice lacking neurotrophin receptors suggested that the effects of NGF on gene expression require TrkA whereas those of NT3 require TrkA and p75(NTR). These findings demonstrate that endogenous NGF and NT3 have distinctive and separate effects on gene expression in early sympathetic neurons and that these selective effects on gene expression require a different combination of neurotrophin receptors.
Andres
Rosa
R
Life Sciences Building, School of Biosciences, Museum Avenue, Cardiff CF10 3US, Wales, United Kingdom.
Herraez-Baranda
Luis A
LA
Thompson
Jane
J
Wyatt
Sean
S
Davies
Alun M
AM
D000818:Animals; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism; D004622:Embryo, Mammalian; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D020932:Nerve Growth Factor / Q000172:deficiency / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D020933:Neurotrophin 3 / Q000172:deficiency / Q000502:physiology*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000235:genetics / Q000378:metabolism; D020800:Receptor, Nerve Growth Factor / Q000172:deficiency; D020917:Receptor, trkA / Q000172:deficiency; D011978:Receptors, Nicotinic / Q000235:genetics / Q000378:metabolism; D017783:Superior Cervical Ganglion / Q000166:cytology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D004299:Dopamine beta-Hydroxylase; D020932:Nerve Growth Factor; D020933:Neurotrophin 3; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D020800:Receptor, Nerve Growth Factor; D020917:Receptor, trkA; D011978:Receptors, Nicotinic; D014446:Tyrosine 3-Monooxygenase; C495402:Adcyap1 protein, mouse