Expression pattern of leucine-rich repeat neuronal protein 4 in adult mouse dorsal root ganglia

• Published in: Neuroscience letters 2012-11, Vol.531 (1), p.24-29
• Main Authors: Bando, Takayoshi, Morikawa, Yoshihiro, Hisaoka, Tomoko, Komori, Tadasuke, Miyajima, Atsushi, Senba, Emiko
• Format: Article
• Language: English
• Subjects: Animals; Axotomy - methods; Brain - metabolism; Dorsal root ganglia; Down-Regulation; Ganglia, Spinal - metabolism; Gene Expression Profiling - methods; Gene Expression Profiling - statistics & numerical data; Gene Knock-In Techniques - methods; LacZ knock-in; Leucine-rich repeat; Lrrn4; Mice; Mice, Inbred C57BL; Mice, Transgenic; Molecular Imaging - methods; Nerve Tissue Proteins - biosynthesis; Neurons - metabolism; Proteins - metabolism; Ret; Sciatic Nerve - metabolism; Trigeminal Ganglion - metabolism; TrkA
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2012.10.009

► We investigated the expression of Lrrn4 in the adult and injured DRGs. ► To characterize Lrrn4-expressing cells, we used Lrrn4 reporter knock-in mice. ► Lrrn4 expression was exclusively observed in a subset of small-sized DRG neurons. ► The expression of Lrrn4 was down-regulated after sciatic nerve axotomy. A member of leucine-rich repeat neuronal protein family, leucine-rich repeat neuronal protein 4 (Lrrn4), is a type I transmembrane protein. Previously, we have reported that Lrrn4 is expressed in various regions of the central nervous system (CNS) and involved in the memory retention. However, little is known about the role of Lrrn4 in the peripheral nervous system (PNS). Northern blot analysis revealed that Lrrn4 mRNA was expressed predominantly in the dorsal root ganglia (DRGs) with low levels in some regions of the CNS. To identify Lrrn4-expressing cells in the DRGs, we performed in situ hybridization histochemistry and LacZ staining in Lrrn4-heterozygous (Lrrn4+/−) mice generated by the replacement of Lrrn4 gene with β-galactosidase gene. In the adult DRGs, 8% of total DRG neurons contained Lrrn4 mRNA, which was exclusively expressed in the small-sized neurons. LacZ staining combined with immunohistochemistry revealed that approximately 42% and 58% of Lrrn4-positive neurons contained receptor tyrosine kinase A (TrkA)- and Ret-immunoreactivity, respectively. After sciatic nerve axotomy, the expression of Lrrn4 mRNA was reduced in injured side of the DRGs. Thus, Lrrn4 is expressed in a subset of nociceptive neurons and might contribute to the maintenance of nociceptive circuits.