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Study of NLS-RARα on Differentiation Inhibition and Its Mechanism of Human Leukemia Cell Line NB4
Xiao Chunlan1, 2, Liu Beizhong1, 2, Xu Ting1, Shan Zhiling2, Gan Liugen1, Song Hao1, Yang Rong2, Li Liu2, Zhong Liang2*
1Central Laboratory of Yongchuan Hospital, Chongqing Medical University, Chongqing 402160, China;
2Key Laboratory of Laboratory Medical Diagnostics, Ministry of Education, Department of Laboratory Medicine,Chongqing Medical University, Chongqing 400016, China
2Key Laboratory of Laboratory Medical Diagnostics, Ministry of Education, Department of Laboratory Medicine,Chongqing Medical University, Chongqing 400016, China
Abstract: This paper is to investigate the effects of NLS-RARα on differentiation of human promyelocytic leukemia cell line NB4 and its potential mechanisms. The expressions of myeloid differentiation markers， C/EBPβ and CD11b， p38α induced by ATRA in NB4 cells were detected by Western blot. NLS-RARα was overexpressed mediating by lentivirus and its efficiency of NLS-RARα overexpress， the expressions of myeloid differentiation markers， C/EBPβ and CD11b， p38α were detected by Western blot. The localization of NLS-RARα and its interaction with p38α was analysed by indirect immunofluorescence assay and co-immunopreci-pitation assay， respectively. Our results demonstrated that the two ATRA concentrations (physiological [10 nmol/L] and pharmacological [1 μmol/L] concentrations) that we investigated promoted differentiation and activated p38α in NB4 cells. Further， ATRA-induced expression of the myeloid differentiation marker， C/EBPβ， was proportional to phosphorylated p38α (p-p38α).We also observed a higher peak in the surface of myeloid differentiation marker， CD11b， following treatment with pharmacological concentrations of ATRA (1 μmol/L). NLS-RARα also inhibited NB4 cell differentiation，more importantly， this effect was related to downregulation of the active form of p38α in the presence of ATRA.Finally， co-localization of NLS-RARα and p38α in three-dimensional space was confirmed， and we found that NLS-RARα could interact with p38α directly. Taken together， these data indicated that NLS-RARα inhibited ATRA-induced differentiation of NB4 cells by downregulating the active form of p38α via a direct interaction with p38α.
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