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Both ERK and JNK are required for enhancement of MD‐2 gene expression during differentiation of HL‐60 cells
Author(s) -
Li Changlin,
Yu Yongshen,
Wang Yun,
Liu Lei,
Zhang Min,
Sugano Sumio,
Wang Zhengguo,
Chang Zongliang
Publication year - 2008
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1042/bc20070140
Subject(s) - mapk/erk pathway , biology , microbiology and biotechnology , kinase , gene expression , p38 mitogen activated protein kinases , protein kinase a , transcription factor , regulation of gene expression , transfection , gene , biochemistry
Background information . MD‐2 is associated with the extracellular domain of TLR4 (Toll‐like receptor 4) and augments TLR4‐dependent LPS (lipopolysaccharide) responses in vitro . Our previous investigation found that PMA‐induced HL‐60 cell differentiation to macrophages is associated largely with TLR2 and CD14 and, to a much lesser extent, with TLR4. Results . We studied the MD‐2 expression during differentiation of HL‐60 cells induced by PMA. The results showed that PMA, but not VitD 3 (1α,25‐dihydroxy‐vitamin D 3 ), strongly induces MD‐2 gene expression by HL‐60 cells in a time‐ and dose‐dependent manner. Treatment with an MEK [MAPK (mitogen‐activated protein kinase)/ERK (extracellular‐signal‐regulated kinase) kinase] inhibitor (PD98059) and a JNK (c‐Jun N‐terminal kinase) inhibitor (SP600125) suppresses PMA‐induced MD‐2 gene expression, whereas impairment of p38 function by treatment with the inhibitor SB203580 has no effect on MD‐2 mRNA. In order to reveal the possible molecular mechanism for such a regulation of MD‐2 gene expression, we cloned and analysed the putative MD‐2 gene promoter. Transient transfection of different deletion mutants demonstrated that the region −185/−171 (5′‐TCCTTTACAGGAAGT‐3′) of the MD‐2 gene promoter is closely related to gene transcription in response to PMA. Additionally, the transcription factor Elk‐1 has been found to bind this specific motif. Conclusions . These results suggest that ERK and JNK pathways are involved in PMA‐mediated MD‐2 gene expression during HL‐60 cell differentiation, and the activation of the MEK/possible ERK/Elk signal pathway is the mechanism responsible for PMA‐induced MD‐2 gene expression in differentiated HL‐60 cells.