Expression of mRNA encoding neurotrophins and neurotrophin receptors in rat thymus, spleen tissue and immunocompetent cells

Abstract

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 nervegrowth‐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.

The expanding role of nerve growth factor: from neurotrophic activity to immunologic diseases

“…This hypothesis is supported by in vivo studies showing NGF-r expression on stromal and immune cells within lymphoid organs (96)(97)(98)(99).…”

Brain-Derived Neurotrophic Factor Regulates the Onset and Severity of Motor Dysfunction Associated with Enkephalinergic Neuronal Degeneration in Huntington's Disease

“…Serial coronal cryostat sections (14 m) were processed for hybridization with radioactive riboprobes (Ibanez et al, 1992;Laurenzi et al, 1994;Lindefors et al, 1995) as described previously (Canals et al, 2001). Antisense cRNA probe to detect the transcripts of neurotrophins was prepared by in vitro transcription using T3 or T7 RNA polymerase (Promega) and […”

p75NTR in the spleen: Age‐dependent changes, effect of NGF and 4‐methylcatechol treatment, and structural changes in p75NTR‐deficient mice

“…All neurotrophins have been detected in the rat spleen at the mRNA level (Maisonpierre et al, 1990;Timmusk et al, 1993;Laurenzi et al, 1994), while NT-3 has also been detected at the protein level (Katoh-Semba et al, 1996). Thus, neurotrophins of local or systemic origin (especially NGF (Carlson et al, 1998), whose levels are altered during certain infectious states (Ahmed et al, 1998)) could act on DC through p75 NTR and be among the soluble factors controlling DC maturation (Caux et al, 2002).…”

“…The human (Yamamoto et al, 1996) and rat (Ernfors et al, 1988;Laurenzi et al, 1994;Lomen-Hoerth and Shooter, 1995) spleen contain mRNA for p75 NTR . In immunohistochemical studies, the p75 NTR -expressing cell types have been identified as either B-lymphocytes (Chesa et al, 1988) or follicular dendritic cells (Labouyrie et al, 1997;Fanburg-Smith and Miettinen, 2001) of the human spleen.…”