Slug suppression induces apoptosis via Puma transactivation in rheumatoid arthritis fibroblast-like synoviocytes treated with hydrogen peroxide.
Inadequate apoptosis contributes to synovial hyperplasia in rheumatoid arthritis (RA). Recent study shows that low expression of Puma might be partially responsible for the decreased apoptosis of fibroblast-like synoviocytes (FLS). Slug, a highly conserved zinc finger transcriptional repressor, is known to antagonize apoptosis of hematopoietic progenitor cells by repressing Puma transactivation. In this study, we examined the expression and function of Slug in RA FLS. Slug mRNA expression was measured in the synovial tissue (ST) and FLS obtained from RA and osteoarthritis patients. Slug and Puma mRNA expression in FLS by apoptotic stimuli were measured by real-time PCR analysis. FLS were transfected with control siRNA or Slug siRNA. Apoptosis was quantified by trypan blue exclusion, DNA fragmentation and caspase-3 assay. RA ST expressed higher level of Slug mRNA compared with osteoarthritis ST. Slug was significantly induced by hydrogen peroxide (H2O2) but not by exogenous p53 in RA FLS. Puma induction by H2O2 stimulation was significantly higher in Slug siRNA-transfected FLS compared with control siRNA-transfected FLS. After H2O2 stimulation, viable cell number was significantly lower in Slug siRNA-transfected FLS compared with control siRNA-transfected FLS. Apoptosis enhancing effect of Slug siRNA was further confirmed by ELISA that detects cytoplasmic histone-associated DNA fragments and caspase-3 assay. These data demonstrate that Slug is overexpressed in RA ST and that suppression of Slug gene facilitates apoptosis of FLS by increasing Puma transactivation. Slug may therefore represent a potential therapeutic target in RA.
Cha
Hoon-Suk
HS
Department of Medicine, Samsung Medical Center, Seoul 135-710, Korea.
Bae
Eun-Kyung
EK
Ahn
Joong Kyong
JK
Lee
Jaejoon
J
Ahn
Kwang-Sung
KS
Koh
Eun-Mi
EM
D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D051017:Apoptosis Regulatory Proteins / Q000235:genetics* / Q000378:metabolism; D001172:Arthritis, Rheumatoid / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002478:Cells, Cultured; D004353:Drug Evaluation, Preclinical; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology*; D000071250:Snail Family Transcription Factors; D013583:Synovial Membrane / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D014157:Transcription Factors / Q000037:antagonists & inhibitors* / Q000235:genetics; D015533:Transcriptional Activation / Q000187:drug effects; D014162:Transfection
D051017:Apoptosis Regulatory Proteins; C438378:BBC3 protein, human; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; C000604407:SNAI1 protein, human; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D006861:Hydrogen Peroxide