IL-6 plays a critical role in the synergistic induction of human serum amyloid A (SAA) gene when stimulated with proinflammatory cytokines as analyzed with an SAA isoform real-time quantitative RT-PCR assay system.
Serum amyloid A (SAA) is known to be a precursor of amyloid A (AA) protein in AA (secondary) amyloidosis and SAA1 to be mainly involved in AA amyloidosis. We established an SAA isoform real-time quantitative RT-PCR assay and found that beta-2 microglobulin is more stable as an internal control than GAPDH and beta-actin for our system. Either IL-6 and IL-1beta or IL-6 and TNFalpha, but not IL-1beta and TNFalpha, induced the synergistic induction of SAA1 and SAA2 genes. Anti-IL-6 receptor monoclonal antibody completely inhibited the synergistic induction of SAA1 and SAA2 during triple stimulation with IL-6, IL-1beta, and TNFalpha, but, IL-1 receptor antagonist or anti-TNFalpha monoclonal antibody was only partially inhibited in HepG2, Hep3B, and PLC/PRF/5 cells. Although the SAA1 promoter has no STAT3 consensus sequence, the JAK2 inhibitor-AG490 reduced SAA1 gene expression to 30%, suggesting the involvement of STAT3. We were able to demonstrate that IL-6 plays a critical role in the synergistic induction of human SAA gene when stimulated with proinflammatory cytokines.
Hagihara
Keisuke
K
Department of Medical Science I, School of Health and Sport Sciences, Osaka University, Osaka, Japan.
Nishikawa
Teppei
T
Isobe
Tomoyasu
T
Song
Jian
J
Sugamata
Yasuhiro
Y
Yoshizaki
Kazuyuki
K
D000199:Actins / Q000378:metabolism; D000682:Amyloid / Q000737:chemistry; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000378:metabolism; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D016207:Cytokines / Q000096:biosynthesis*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism / Q000502:physiology*; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050796:STAT3 Transcription Factor; D000685:Serum Amyloid A Protein / Q000737:chemistry / Q000235:genetics*; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020032:Tyrphostins / Q000494:pharmacology; D001613:beta 2-Microglobulin / Q000378:metabolism
D000199:Actins; D000682:Amyloid; D000911:Antibodies, Monoclonal; D016207:Cytokines; D004268:DNA-Binding Proteins; D007375:Interleukin-1; D015850:Interleukin-6; D020033:Protein Isoforms; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D000685:Serum Amyloid A Protein; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; D020032:Tyrphostins; C095512:alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide; D001613:beta 2-Microglobulin