Expression of mRNA encoding neurotrophins and neurotrophin receptors in rat thymus, spleen tissue and immunocompetent cells. Regulation of neurotrophin-4 mRNA expression by mitogens and leukotriene B4.
The expression of neurotrophin and neurotrophin receptor mRNAs was examined using RNase protection assays and Northern-blot analysis in rat thymus, spleen tissue and immunocompetent mononuclear cells purified from these two organs. Nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3 and neurotrophin-4 mRNAs were all expressed in thymus and spleen tissue although at different levels, while immunocompetent cells expressed neurotrophin-3 and neurotrophin-4 mRNAs. Thymus and spleen tissue expressed mRNAs encoding the low-affinity nerve-growth-factor receptor, the non-neuronal TrkA I receptor, the truncated (kinase deficient) and full-length TrkB, and the TrkC receptor. Low-affinity nerve-growth-factor receptor and non-neuronal TrkA I mRNAs were detected in both thymus and spleen immunocompetent cells. In addition, thymus cells expressed neuronal TrkA II mRNA and spleen cells expressed truncated TrkB mRNA. The expression of TrkA I and TrkA II mRNAs was enhanced in both thymus and spleen cells after cell culture. Enhanced levels of neurotrophin-4 mRNA were observed in spleen immunocompetent cells after adrenalectomy. Moreover, the expression of neurotrophin-4 mRNA was up-regulated after stimulation of immune cells with the mitogens concanavalin A or lipopolysaccharide or with the inflammatory mediator leukotriene B4. This suggests that neurotrophin-4 could be secreted by immunocompetent cells and may be involved in inflammatory processes.
Laurenzi
M A
MA
Department of Medical Biochemistry, Karolinska Institute, Stockholm, Sweden.
Barbany
G
G
Timmusk
T
T
Lindgren
J A
JA
Persson
H
H
D000315:Adrenalectomy; D000818:Animals; D005786:Gene Expression Regulation / Q000187:drug effects; D007963:Leukocytes, Mononuclear / Q000737:chemistry*; D007975:Leukotriene B4 / Q000494:pharmacology; D008221:Lymphoid Tissue / Q000737:chemistry* / Q000166:cytology; D008297:Male; D008934:Mitogens / Q000494:pharmacology; D009414:Nerve Growth Factors / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017475:Receptors, Nerve Growth Factor / Q000235:genetics*; D013154:Spleen; D013950:Thymus Gland
D008934:Mitogens; D009414:Nerve Growth Factors; D012333:RNA, Messenger; D017475:Receptors, Nerve Growth Factor; D007975:Leukotriene B4; C073922:neurotrophin 4