title: Activation of STAT3 stimulates AHSP expression in K562 cells.
abstract: Studies on the chaperone protein α-hemoglobin stabilizing protein (AHSP) reveal that abundant AHSP in erythroid cells enhance the cells' tolerance to oxidative stress imposed by excess α-hemoglobin in pathological conditions. However, the potential intracellular modulation of AHSP expression itself in response to oxidative stress is still unknown. The present study examined the effect and molecular mechanism of STAT3, an oxidative regulator, on the expression of AHSP. AHSP expression increased in K562 cells upon cytokine IL-6-induced STAT3 activation and decreased in STAT3 knock-down K562 cells. Regulation of AHSP in oxidative circumstance was then examined in α-globin-overloaded K562 cells, and real-time PCR showed strengthened expression of both AHSP and STAT3. ChIP analysis showed binding of STAT3 to AHSP promoter and binding was significantly augmented with IL6 stimulation and upon α-globin overexpression. Dual luciferase reporter assays of the wildtype and mutated SB3 element, an IL-6RE site, in the AHSP promoter in K562 cells highlighted the direct regulatory effect of STAT3 on AHSP gene. Finally, direct binding of STAT3 to SB3 site of AHSP promoter was confirmed with EMSA assays. Our work reveals an adaptive AHSP regulation mediated by the redox-sensitive STAT3 signaling pathway, and provides clues to the therapeutic strategy for AHSP enhancement.
authors.affiliation: State Key Laboratory of Medical Molecular Biology, Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100005, China.
authors.forename: Cong
authors.initials: C
authors.lastname: Cao
authors.forename: GuoWei
authors.initials: G
authors.lastname: Zhao
authors.forename: Wei
authors.initials: W
authors.lastname: Yu
authors.forename: XueMin
authors.initials: X
authors.lastname: Xie
authors.forename: WenTian
authors.initials: W
authors.lastname: Wang
authors.forename: RuiFeng
authors.initials: R
authors.lastname: Yang
authors.forename: Xiang
authors.initials: X
authors.lastname: Lv
authors.forename: DePei
authors.initials: D
authors.lastname: Liu
mesh_terms: D001665:Binding Sites / Q000235:genetics; D001798:Blood Proteins / Q000235:genetics*; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D020014:K562 Cells; D018832:Molecular Chaperones / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D055542:alpha-Globins / Q000235:genetics
chemical_list: C468768:AHSP protein, human; D001798:Blood Proteins; C508600:IL6 protein, human; D015850:Interleukin-6; D018832:Molecular Chaperones; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D055542:alpha-Globins