NO-cGMP mediated galanin expression in NGF-deprived or axotomized sensory neurons.
Leukaemia inhibitory factor (LIF) and nerve growth factor (NGF) are well characterized regulators of galanin expression. However, LIF knockout mice containing the rat galanin 5' proximal promoter fragment (- 2546 to + 15 bp) driving luciferase responded to axotomy in the same way as control mice. Also, LIF had no effect on reporter gene expression in vitro, neither in the presence or absence of NGF, suggesting that other factors mediate an axotomy response from the galanin promoter. We then addressed the role of nitric oxide (NO) using NGF-deprived rat dorsal root ganglion (DRG) neuron cultures infected with viral vectors containing the above-mentioned construct, and also studied endogenous galanin expression in axotomized DRG in vivo. Blocking endogenous NO in NGF-deprived DRG cultures suppressed galanin promoter activity. Consistent with this, axotomized/NGF-deprived DRG neurons expressed high levels of neuronal NO synthase (nNOS) and galanin. Further, using pharmacological NOS blockers, or adenoviral vectors expressing dominant-negative either for nNOS or soluble guanylate cyclase in vivo and in vitro, we show that the NO-cGMP pathway induces endogenous galanin in DRG neurons. We propose that both LIF and NO, acting at different promoter regions, are important for the up-regulation of galanin, and for DRG neuron survival and regeneration after axotomy.
Thippeswamy
Thimmasettappa
T
Department of Veterinary Preclinical Science, Veterinary Faculty, University of Liverpool, Liverpool, UK. tswamy@liv.ac.uk
Haddley
Kate
K
Corness
Jacquie D
JD
Howard
Mark R
MR
McKay
Jennifer S
JS
Beaucourt
Stephanie M
SM
Pope
Marion D
MD
Murphy
David
D
Morris
Richard
R
Hökfelt
Tomas
T
Quinn
John P
JP
D000818:Animals; D019771:Axotomy; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism*; D019004:Galanin / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics; D017930:Genes, Reporter / Q000235:genetics; D005822:Genetic Vectors / Q000235:genetics; D053605:Leukemia Inhibitory Factor / Q000235:genetics; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D020932:Nerve Growth Factor / Q000172:deficiency*; D009416:Nerve Regeneration / Q000187:drug effects / Q000235:genetics; D009475:Neurons, Afferent / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D020426:Sciatic Neuropathy / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology
D053605:Leukemia Inhibitory Factor; D009569:Nitric Oxide; D019004:Galanin; D020932:Nerve Growth Factor; D019001:Nitric Oxide Synthase; D006152:Cyclic GMP