title: 17β-estradiol induces CD40 expression in dendritic cells via MAPK signaling pathways in a minichromosome maintenance protein 6-dependent manner.
abstract: OBJECTIVE
  The human immune system exhibits sexual dimorphism in autoimmune diseases such as systemic lupus erythematosus (SLE). Female sex hormones, including 17β-estradiol, are strongly implicated in the gender bias in SLE. CD40 is a costimulatory molecule and plays a crucial role in modulating the immune response of effector cells. We have previously shown that 17β-estradiol up-regulated CD40 expression and altered minichromosome maintenance protein 6 (MCM6) gene expression in dendritic cells (DCs). The mechanism of the correlation between CD40 and MCM6 in the presence of 17β-estradiol remains unknown. This study was undertaken to elucidate this mechanism and to explain the role of MCM6 in the gender bias in SLE.
  
  
  METHODS
  Bone marrow-derived DCs transfected with small interfering RNA (siRNA) for MCM6 were treated with 17β-estradiol in the absence or presence of CpG. The expression levels of costimulatory molecules, activity of MAPKs, and levels of MCM6 protein were measured. Moreover, the functions of DCs, including proliferation, apoptosis, endocytosis, and cytokine production, were analyzed. In addition, levels of messenger RNA for MCM6 were detected in DCs purified from SLE patients.
  
  
  RESULTS
  Regardless of the presence or absence of CpG, 17β-estradiol induced CD40 expression via the activation of p38 and JNK, but not ERK. The activation of p38 and JNK enhanced MCM6 expression, which then induced CD40 expression. Suppression of MCM6 in DCs abolished the up-regulation of 17β-estradiol-induced CD40 expression. Importantly, MCM6 expression was significantly increased in SLE patients compared with healthy controls.
  
  
  CONCLUSIONS
  Our findings indicate that 17β-estradiol induces CD40 expression in DCs via p38 and JNK MAPKs in an MCM6-dependent manner. MCM6 may be a critical mediator of sex-based differences in autoimmune disease.
authors.affiliation: Nanjing University Medical School, Nanjing, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Xie
authors.forename: Chunyan
authors.initials: C
authors.lastname: Hua
authors.forename: Lin
authors.initials: L
authors.lastname: Sun
authors.forename: Xiaoyin
authors.initials: X
authors.lastname: Zhao
authors.forename: Hongye
authors.initials: H
authors.lastname: Fan
authors.forename: Huan
authors.initials: H
authors.lastname: Dou
authors.forename: Lingyun
authors.initials: L
authors.lastname: Sun
authors.forename: Yayi
authors.initials: Y
authors.lastname: Hou
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D019013:CD40 Antigens / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003713:Dendritic Cells / Q000187:drug effects* / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008297:Male; D051379:Mice; D008875:Middle Aged; D064151:Minichromosome Maintenance Complex Component 6; D034741:RNA, Small Interfering
chemical_list: D019013:CD40 Antigens; D018797:Cell Cycle Proteins; D034741:RNA, Small Interfering; D004958:Estradiol; C103258:MCM6 protein, human; D064151:Minichromosome Maintenance Complex Component 6