Double-stranded RNA induces iNOS gene expression in Schwann cells, sensory neuronal death, and peripheral nerve demyelination.
Inflammation in the peripheral nervous system (PNS) is one of the characteristics of virus-induced peripheral neuropathy. In this inflammatory response, Schwann cells are actively involved. Previously, toll-like receptor 3 (TLR3) was reported as a receptor for double-stranded RNA (dsRNA) that induces antiviral and inflammatory responses in cells of the innate immune system. In this study, we investigated the expression and putative role of TLR3 in Schwann cells. TLR3 was constitutively expressed in Schwann cells. Stimulation with polyinosinic-polycytidylic acid, a synthetic dsRNA analogue, induced the expression of inducible nitric oxide synthase (iNOS) gene in Schwann cells. Studies on the intracellular signal transduction pathways using iSC, an immortalized Schwann cell line, revealed that dsRNA induces the activation of NF-kappaB, p38, and c-Jun N-terminal kinase (JNK). The activation of NF-kappaB, p38, JNK, and dsRNA-dependent protein kinase is required for dsRNA-mediated iNOS gene expression. However, the activation of PI3 kinase and GSK-3beta inhibited iNOS gene induction, a process mediated by their inhibitory effects on NF-kappaB and p38 activation. dsRNA-induced NO production caused neuronal cell death in cultured dorsal root ganglion. Finally, the introduction of dsRNA into the rat sciatic nerve induced iNOS gene expression and peripheral nerve demyelination in vivo. Taken together, these data suggest that viral RNA may induce inflammatory Schwann cell activation via TLR3 and peripheral nerve damage in the PNS.
Lee
Hyunkyoung
H
Program in Molecular and Cellular Neuroscience, Dental Research Institute, Seoul National University, 28 Yeongun-dong, Jongno-gu, Seoul 110-749, Korea.
Park
Chanhee
C
Cho
Ik-Hyun
IH
Kim
Hyun Yeong
HY
Jo
Eun-Kyeong
EK
Lee
Soojin
S
Kho
Hong-Seop
HS
Choi
Se-Young
SY
Oh
Seog Bae
SB
Park
Kyungpyo
K
Kim
Joong Soo
JS
Lee
Sung Joong
SJ
D000818:Animals; D000831:Animals, Newborn; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D018920:Coculture Techniques; D003711:Demyelinating Diseases / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology; D004790:Enzyme Induction / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000235:genetics; D007249:Inflammation / Q000139:chemically induced / Q000201:enzymology / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009410:Nerve Degeneration / Q000139:chemically induced / Q000201:enzymology / Q000235:genetics; D009475:Neurons, Afferent / Q000187:drug effects* / Q000473:pathology; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis* / Q000235:genetics; D010525:Peripheral Nerves / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D010523:Peripheral Nervous System Diseases / Q000139:chemically induced* / Q000201:enzymology / Q000473:pathology; D011070:Poly I-C / Q000494:pharmacology; D012330:RNA, Double-Stranded / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012583:Schwann Cells / Q000187:drug effects* / Q000201:enzymology; D015398:Signal Transduction / Q000502:physiology; D051196:Toll-Like Receptor 3 / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
D012330:RNA, Double-Stranded; D051196:Toll-Like Receptor 3; D052247:Nitric Oxide Synthase Type II; D011070:Poly I-C