JAK-STAT signaling mediates gangliosides-induced inflammatory responses in brain microglial cells.
Neuronal cell membranes are particularly rich in gangliosides, which play important roles in brain physiology and pathology. Previously, we reported that gangliosides could act as microglial activators and are thus likely to participate in many neuronal diseases. In the present study we provide evidence that JAK-STAT inflammatory signaling mediates gangliosides-stimulated microglial activation. Both in rat primary microglia and murine BV2 microglial cells, gangliosides stimulated nuclear factor binding to GAS/ISRE elements, which are known to be STAT-binding sites. Consistent with this, gangliosides rapidly activated JAK1 and JAK2 and induced phosphorylation of STAT1 and STAT3. In addition, gangliosides increased transcription of the inflammation-associated genes inducible nitric-oxide synthase, ICAM-1, and MCP-1, which are reported to contain STAT-binding elements in their promoter regions. AG490, a JAK inhibitor, reduced induction of these genes, nuclear factor binding activity, and activation of STAT1 and -3 in gangliosides-treated microglia. AG490 also inhibited gangliosides-induced release of nitric oxide, an inflammation hallmark. Furthermore, AG490 markedly reduced activation of ERK1/2 MAPK, indicating that ERKs act downstream of JAK-STAT signaling during microglial activation. However, AG490 did not affect activation of p38 MAPK. We also report that the sialic acid residues present on gangliosides may be one of the essential components in activation of JAK-STAT signaling. The present study indicates that JAK-STAT signaling is an early event in gangliosides-induced brain inflammatory responses.
Kim
Ohn Soon
OS
Department of Pharmacology, School of Medicine, Ajou University, Suwon 442-721, Korea.
Park
Eun Jung
EJ
Joe
Eun-hye
EH
Jou
Ilo
I
D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D004789:Enzyme Activation; D005732:Gangliosides / Q000378:metabolism*; D018836:Inflammation Mediators / Q000378:metabolism*; D017628:Microglia / Q000378:metabolism* / Q000473:pathology; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism*; D020032:Tyrphostins / Q000494:pharmacology
D017931:DNA Primers; D004268:DNA-Binding Proteins; D005732:Gangliosides; D018836:Inflammation Mediators; D009687:Nuclear Proteins; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; C494081:Stat1 protein, rat; C494088:Stat3 protein, rat; D015534:Trans-Activators; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D011505:Protein-Tyrosine Kinases; D019158:N-Acetylneuraminic Acid