Mutual induction of TGFbeta1 and NGF after treatment with NGF or TGFbeta1 in grafted chromaffin cells of the adrenal medulla.
Chromaffin cells have been recognized for their ability to transform into sympathetic ganglion-like cells in response to nerve growth factor (NGF) or to stimulation of other neurotrophic factors. Transforming growth factor beta (TGFbeta) family members have been shown to potentiate the effect of different trophic factors. The aim of this study was to investigate if TGFbeta may influence NGF-induced neuronal transformation and regulation of NGF, TGFbeta1, and their receptors in the adult rat chromaffin tissue after grafting. Intraocular transplantation of adult chromaffin tissue was employed and grafts were treated with TGFbeta1 and/or NGF. Graft survival time was 18 days after which the grafts were processed for TGFbeta luciferase detection assay, NGF enzyme immunoassay, or in situ hybridization. In grafts stimulated with NGF, increased levels of TGFbeta1 and TGFbeta1 mRNA were detected. When grafts instead were treated with TGFbeta1, enhanced levels of NGF protein were found. Furthermore, a positive mRNA signal corresponding to the transforming growth factor II receptor (TbetaRII) was found in the chromaffin cells of the normal adrenal medulla as well as after grafting. No increase of TbetaRII mRNA levels was detected after transplantation or after TGFbeta1 treatment. Instead a reduction of TbetaRII mRNA expression was noted after NGF treatment. NGF stimulation of grafts increased the message for NGF receptors p75 and trkA in the chromaffin transplants. Grafts processed for evaluations of neurite outgrowth were allowed to survive for 28 days and were injected weekly with NGF and/or TGFbeta1. NGF treatment resulted in a robust innervation of the host irides. TGFbeta1 had no additive effect on nerve fiber formation when combined with NGF. Combined treatment of NGF and anti-TGFbeta1 resulted in a significantly larger area of reinnervation. In conclusion, it was found that NGF and TGFbeta1 may regulate the expression of each other's protein in adult chromaffin grafts. Furthermore, TbetaRII mRNA was present in the adult rat chromaffin cells and became downregulated as a result of NGF stimulation. Although no synergistic effects of TGFbeta1 were found on NGF-induced neurite outgrowth, it was found that TGFbeta1 and NGF signaling are closely linked in the chromaffin cells of the adrenal medulla.
Department of Neuroscience, Karolinska Institutet, Stockholm, S-171 77, Sweden.
P
P
Förander
K
K
Krieglstein
S
S
Söderström
I
I
Strömberg
D000313:Adrenal Medulla / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D000867:Anterior Chamber / Q000166:cytology / Q000601:surgery; D002470:Cell Survival / Q000187:drug effects; D019439:Chromaffin Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000637:transplantation*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D004333:Drug Administration Routes; D005260:Female; D006085:Graft Survival; D017403:In Situ Hybridization; D007267:Injections; D020932:Nerve Growth Factor / Q000008:administration & dosage / Q000096:biosynthesis*; D016501:Neurites / Q000187:drug effects / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020800:Receptor, Nerve Growth Factor / Q000235:genetics / Q000378:metabolism; D000077294:Receptor, Transforming Growth Factor-beta Type II; D020917:Receptor, trkA / Q000235:genetics / Q000378:metabolism; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000008:administration & dosage / Q000096:biosynthesis* / Q000235:genetics
D012333:RNA, Messenger; D020800:Receptor, Nerve Growth Factor; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D020932:Nerve Growth Factor; D020917:Receptor, trkA; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II