TNFalpha induces acetylation of p53 but attenuates its transcriptional activation in rheumatoid synoviocytes.
Synovial hyperplasia is an important feature of rheumatoid arthritis (RA) and we have reported that several transcription factors were highly activated in rheumatoid synoviocytes. The purpose of this study was to examine nuclear acetylation in synoviocytes as an activation marker and determine its role in cell activation. Autonomous acetylation of approximately 53 and 62 kDa nuclear proteins was detected in rheumatoid synoviocytes by anti-acetylated lysine specific antibody. Furthermore, tumor necrosis factor alpha (TNFalpha), a potent mitogen for synoviocytes, dose-dependently increased their state of acetylation. Immunoprecipitation analysis revealed that 53 kDa acetylated protein (ap53) was identical with p53, a tumor suppressor gene product. Since enhanced p53 binding to the promoter by TNFalpha treatment was detected by gel shift assay, we analyzed p53 promoter activity by reporter assay system. Contrary to enhanced binding activity, the transcriptional activity was attenuated in a TNFalpha concentration-dependent manner. Since p53 activation requires recruitment of CREB binding protein (CBP) as a coactivator, we also examined the effect of CBP on TNFalpha-induced attenuation of p53 promoter activation. Overexpression of CBP induced p53 transcriptional activity and recovery of TNFalpha-induced inhibition. Our results clearly indicate that autonomous nuclear acetylation is characteristically enhanced in rheumatoid synoviocytes and that p53 is one of acetylated protein. Our results also demonstrate that TNFalpha-induced acetylation of p53 attenuated its transcriptional activation via CBP depletion, and that overexpression of CBP enhanced TNFalpha-induced cell death in rheumatoid synoviocytes, suggesting that regulation of transcriptional coactivator become a novel strategy for RA therapy.
Nakazawa
Minako
M
Rheumatology, Immunology and Genetics Program, Institute of Medical Science, St. Marianna University, School of Medicine, Kanagawa, Japan.
Aratani
Satoko
S
Hatta
Mitsutoki
M
Araya
Natsumi
N
Daitoku
Hiroaki
H
Kawahara
Ko-Ichi
K
Watanabe
Shin-Ichi
S
Nakamura
Hiroshi
H
Yoshino
Shin-Ichi
S
Fujii
Ryouji
R
Fujita
Hidetoshi
H
Fukamizu
Akiyoshi
A
Nishioka
Kusuki
K
Nakajima
Toshihiro
T
D000107:Acetylation; D017209:Apoptosis; D001172:Arthritis, Rheumatoid / Q000378:metabolism; D015153:Blotting, Western; D050882:CREB-Binding Protein; D002467:Cell Nucleus / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009687:Nuclear Proteins / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D013582:Synovial Fluid / Q000166:cytology*; D015534:Trans-Activators / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
D007074:Immunoglobulin G; D009687:Nuclear Proteins; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha; D016159:Tumor Suppressor Protein p53; D050882:CREB-Binding Protein; C494363:CREBBP protein, human