title: Sumoylation of the Tumor Suppressor Promyelocytic Leukemia Protein Regulates Arsenic Trioxide-Induced Collagen Synthesis in Osteoblasts.
abstract: OBJECTIVE
  Promyelocytic leukemia (PML) protein is a tumor suppressor that fuses with retinoic acid receptor-α (PML-RARα) to contribute to the initiation of acute promyelocytic leukemia (APL). Arsenic trioxide (ATO) upregulates expression of TGF-β1, promoting collagen synthesis in osteoblasts, and ATO binds directly to PML to induce oligomerization, sumoylation, and ubiquitination. However, how ATO upregulates TGF-β1 expression is uncertain. Thus, we suggested that PML sumoylation is responsible for regulation of TGF-β1 protein expression.
  
  
  METHODS
  Kunming mice were treated with ATO, and osteoblasts were counted under scanning electron microscopy. Masson's staining was used to quantify collagen content. hFOB1.19 cells were transfected with siRNA against UBC9 or RNF4, and then treated with ATO or FBS. TGF-β1, PML expression, and sumoylation were quantified with Western blot, and collagen quantified via immunocytochemistry.
  
  
  RESULTS
  ATO enhanced osteoblast accumulation, collagen synthesis, and PML-NB formation in vivo. Knocking down UBC9 in hFOB1.19 cells inhibited ATO- and FBS-induced PML sumoylation, TGF-β1 expression, and collagen synthesis. Conversely, knocking down RNF4 enhanced ATO- and FBS-induced PML sumoylation, TGF-β1 expression, and collagen synthesis.
  
  
  CONCLUSIONS
  These data suggest that PML sumoylation is required for ATO-induced collagen synthesis in osteoblasts.
authors.forename: Wen-Xiao
authors.initials: WX
authors.lastname: Xu
authors.forename: Sheng-Zhi
authors.initials: SZ
authors.lastname: Liu
authors.forename: Di
authors.initials: D
authors.lastname: Wu
authors.forename: Guo-Fen
authors.initials: GF
authors.lastname: Qiao
authors.forename: Jinglong
authors.initials: J
authors.lastname: Yan
mesh_terms: D000818:Animals; D000077237:Arsenic Trioxide; D001152:Arsenicals; D002460:Cell Line; D003094:Collagen / Q000378:metabolism*; D005269:Femur / Q000473:pathology; D006801:Humans; D008297:Male; D051379:Mice; D008854:Microscopy, Electron; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010087:Oxides / Q000633:toxicity*; D000071156:Promyelocytic Leukemia Protein; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D025842:SUMO-1 Protein / Q000378:metabolism; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism; D058207:Sumoylation / Q000187:drug effects*; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: D001152:Arsenicals; D009687:Nuclear Proteins; D010087:Oxides; D000071156:Promyelocytic Leukemia Protein; D034741:RNA, Small Interfering; C114070:RNF4 protein, human; D025842:SUMO-1 Protein; C117909:SUMO2 protein, human; D025841:Small Ubiquitin-Related Modifier Proteins; D014157:Transcription Factors; D053773:Transforming Growth Factor beta1; D025521:Tumor Suppressor Proteins; C070576:PML protein, human; D003094:Collagen; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9; D000077237:Arsenic Trioxide