Premium
Prothrombin kringle‐2 induces death of mesencephalic dopaminergic neurons in vivo and in vitro via microglial activation
Author(s) -
Kim Sang Ryong,
Chung Eun Sook,
Bok Eugene,
Baik Hyung Hwan,
Chung Young Cheul,
Won So Yoon,
Joe Eunhye,
Kim Tae Hyong,
Kim Soung Soo,
Jin Min Young,
Choi Sang Ho,
Jin Byung Kwan
Publication year - 2009
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.22318
Subject(s) - microglia , neurotoxicity , protein kinase r , proinflammatory cytokine , nitric oxide synthase , chemistry , microbiology and biotechnology , biology , kinase , protein kinase a , nitric oxide , endocrinology , inflammation , immunology , mitogen activated protein kinase kinase , toxicity , organic chemistry
We have shown that prothrombin kringle‐2 (pKr‐2), a domain of human prothrombin distinct from thrombin could activate cultured rat brain microglia in vitro. However, little is known whether pKr‐2‐induced microglial activation could cause neurotoxicity on dopaminergic (DA) neurons in vivo. To address this question, pKr‐2 was injected into the rat substantia nigra (SN). Tyrosine hydroxylase (TH) immunohistochemistry experiments demonstrate significant loss of DA neurons seven days after injection of pKr‐2. In parallel, pKr‐2‐activated microglia were detected in the SN with OX‐42 and OX‐6 immunohistochemistry. Reverse transcription PCR and double‐label immunohistochemistry revealed that activated microglia in vivo exhibit early and transient expression of inducible nitric oxide synthase (iNOS), cyclooxygenase‐2 (COX‐2) and several proinflammatory cytokines. The pKr‐2‐induced loss of SN DA neurons was partially inhibited by the NOS inhibitor N G ‐nitro‐L‐arginine methyl ester hydrochloride, and the COX‐2 inhibitor DuP‐697. Extracellular signal‐regulated kinase 1/2, c‐Jun N‐terminal kinase and p38 mitogen‐activated protein kinase were activated in the SN as early as 1 hr after pKr‐2 injection, and localized within microglia. Inhibition of these kinases led to attenuation of mRNA expression of iNOS, COX‐2 and several proinflammatory cytokines, and rescue of DA neurons in the SN. Intriguingly, following treatment with pKr‐2 in vitro, neurotoxicity was detected exclusively in co‐cultures of mesencephalic neurons and microglia, but not microglia‐free neuron‐enriched mesencephalic cultures, indicating that microglia are required for pKr‐2 neurotoxicity. Our results strongly suggest that microglia activated by endogenous compound(s), such as pKr‐2, are implicated in the DA neuronal cell death in the SN. © 2009 Wiley‐Liss, Inc.