Activation of mitogen-activated protein kinases in hamster brains infected with 263K scrapie agent.
We investigated the expression, activation and distribution of c-Jun N-terminal kinases (JNKs), p38 mitogen-activated protein kinases (p38 MAPKs) and extracellular signal-regulated kinases (ERKs), using western blotting and immunohistochemistry, in the brains of hamsters infected with 263K scrapie agent, to clarify the role of these kinases in the pathogenesis of prion disease. The immunoblot analysis demonstrated that activation of JNK, p38 MAPK and ERK in whole brain homogenates was increased in infected animals. Phosphorylation of cAMP/calcium responsive element binding protein (CREB), a downstream transcription factor of active ERK, was significantly increased in scrapie-infected hamsters. The immunohistochemical study showed that active ERK was enhanced in infected hamsters compared with controls. Active ERK immunoreactivity was observed within neurons in the dentate gyrus and in glial fibrillary acidic protein (GFAP)-positive reactive astrocytes of infected animals. The expression level of c-Jun mRNA as well as protein, a substrate of active JNK, was increased in infected animals. A significant increase in JNK activity upon glutathione S-transferase (GST)-c-Jun was observed in infected compared with control animals. Phospho-c-Jun immunoreactivity was observed only in neurons of the thalamus in infected groups. These findings indicated that the JNK pathway was activated in the scrapie-infected group. The chronological activation of MAPKs using immunoblot analysis indicates that the kinases are sequentially activated during the pathophysiology of prion disease. Taken together, these results lend credence to the notion that MAPK pathways are dysregulated in prion disease, and also indicate an active role for this pathway in disease pathogenesis.
Lee
Hyun-Pil
HP
Ilsong Institute of Life Science, Hallym University, Anyang, Kyeonggi-Do, Republic of Korea.
Jun
Yong-Cheol
YC
Choi
Jin-Kyu
JK
Kim
Jae-Il
JI
Carp
Richard I
RI
Kim
Yong-Sun
YS
D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000201:enzymology*; D006224:Cricetinae; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004789:Enzyme Activation / Q000502:physiology; D005260:Female; D007150:Immunohistochemistry; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008647:Mesocricetus; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D018620:PrPSc Proteins / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012608:Scrapie / Q000201:enzymology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D017362:Cyclic AMP Response Element-Binding Protein; D018620:PrPSc Proteins; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases