title: Nuclear receptor subfamily 4, group A, member 1 inhibits extrinsic apoptosis and reduces caspase-8 activity in H2O2-induced human HUC-F2 fibroblasts.
abstract: OBJECTIVE
  Apoptosis is characterized by distinct morphological and biochemical changes that occur upon activation of a family of serine proteases known as caspases. Reactive oxygen species (ROS) induce apoptosis in many cell systems. Nuclear receptor subfamily 4, group A, member 1 (NR4A1) has been shown to induce apoptosis in a number of cell lineages, but can also paradoxically act as a death inhibitory factor. In the current study, we focused on the potential role of NR4A1 in hydrogen peroxide (H2O2)-induced apoptosis of normal human umbilical cord fibroblast (HUC-F2) cells.
  
  
  METHODS
  Growth of HUC-F2 cells treated with H2O2 was measured by MTT assay. Analysis of gene expression was performed with a STEP ONE PLUS Real Time PCR system. Inactivation of NR4A1 was treated with siRNA. Apoptosis was measured by Beckman Coulter flow cytometer after inhibition of NR4A1 with siRNA and H2O2 treatment. Caspase -3, -8 and -9 was measured by caspase assay kit.
  
  
  RESULTS
  H2O2 treatment led to enhanced NR4A1 expression. Moreover inhibition of NR4A1 with specific siRNA in HUC-F2 cells triggered an increase in apoptosis and caspase-8 and -3 activities following the addition of H2O2.
  
  
  CONCLUSIONS
  Our results collectively suggest that NR4A1 is a regulator that inhibits extrinsic apoptosis in HUC-F2 cells during oxidative stress through reduction of caspase-8 and -3 activities.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Reiko
authors.initials: R
authors.lastname: Miyakura
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Otsuka
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism*; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1 / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D034741:RNA, Small Interfering
chemical_list: C539821:NR4A1 protein, human; D057105:Nuclear Receptor Subfamily 4, Group A, Member 1; D034741:RNA, Small Interfering; D006861:Hydrogen Peroxide; D053148:Caspase 3; D053181:Caspase 8
keywords: Apoptosis; Caspase-8; NR4A1; Oxidative stress