Spatial regulation of neuronal gene expression in response to nerve growth factor.
To examine the cellular mechanisms whereby distally derived growth factors regulate nuclear responses in neurons, we have utilized compartmented cultures of sympathetic neurons to examine the regulation of two nerve growth factor (NGF)-inducible genes, tyrosine hydroxylase (TH) and p75 neurotrophin receptor (p75NTR). These studies demonstrate that NGF can signal retrogradely to mediate the induction of TH and p75NTR mRNAs. However, quantitative differences occurred as a function of the spatial localization of NGF exposure; application of NGF to cell bodies and proximal axons elicited peak levels of neuronal gene expression that were two- to threefold higher than when NGF was applied to distal axons alone. Furthermore, neurons responding maximally to NGF on distal axons were still able to respond to NGF administered to cell bodies and proximal axons. Biochemical analysis indicated that this difference in responsiveness was not due to differences in the number of TrkA/NGF receptors in the two compartments. Thus, although NGF signals retrogradely to mediate nuclear responses, the magnitude of these responses differs as a function of the spatial location of the activated NGF receptor:ligand complex. Moreover, these data suggest that neurons may be able to respond to a second cellular source of neurotrophins, even when target-derived neurotrophins are not limiting.
Toma
J G
JG
Center for Neuronal Survival, Montreal Neurological Institute, McGill University, Canada.
Rogers
D
D
Senger
D L
DL
Campenot
R B
RB
Miller
F D
FD
D000818:Animals; D000831:Animals, Newborn; D002451:Cell Compartmentation; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D009414:Nerve Growth Factors / Q000494:pharmacology*; D016501:Neurites; D009474:Neurons / Q000737:chemistry / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis / Q000235:genetics; D020800:Receptor, Nerve Growth Factor; D020917:Receptor, trkA; D017475:Receptors, Nerve Growth Factor / Q000032:analysis / Q000235:genetics; D013564:Sympathetic Nervous System / Q000166:cytology; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis / Q000235:genetics
D009414:Nerve Growth Factors; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D020800:Receptor, Nerve Growth Factor; D017475:Receptors, Nerve Growth Factor; D014446:Tyrosine 3-Monooxygenase; D020794:Receptor Protein-Tyrosine Kinases; D020917:Receptor, trkA