Studies on the chaperone protein α-hemoglobin stabilizing protein （AHSP） reveal that abundant AHSP in erythroid cells en-hance the cells＇ tolerance to oxidative stress imposed by excess a-hemoglobin in pathological conditions. However, the poten-tial intracellular modulation of AHSP expression itself in response to oxidative stress is still unknown. The present study ex-amined 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. Reg-ulation 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 ef-fect of STAT3 on AHSP gene. Finally, direct binding of STAT3 to SB3 site of AHSP promoter was confirmed with EMSA as-says. 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.
CAO CongZHAO GuoWeiYU WeiXIE XueMinWANG WenTianYANG RuiFengLV XiangLIU DePei
