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Nucleocytoplasmic shuttling of HMGB1 is regulated by phosphorylation that redirects it toward secretion
被引:302
作者:
Youn, Ju Ho
Shin, Jeon-Soo
机构:
[1] Yonsei Univ, Coll Med, Dept Microbiol, Brain Korea Project Med Sci 21, Seoul 120752, South Korea
[2] Yonsei Univ, Coll Med, Inst Immunol & Immunol Dis, Seoul 120752, South Korea
[3] Yonsei Univ, Coll Med, Natl Core Res Ctr Nanomed Technol, Seoul 120752, South Korea
关键词:
D O I:
10.4049/jimmunol.177.11.7889
中图分类号:
R392 [医学免疫学];
Q939.91 [免疫学];
学科分类号:
100102 ;
摘要:
The high mobility group box 1 (HMGB1) protein can be secreted by activated monocytes and macrophages and functions as a late mediator of sepsis. HA4GB1 contains two nuclear localization signals (NLSs) for controlled nuclear transport, and acetylation of both NLSs of HMGB1 is involved in nuclear transport toward secretion. However, phosphorylation of HMGB1 and its relation to nuclear transport have not been shown. We show here that HMGB1 is phosphorylated and dynamically shuttled between cytoplasmic and nuclear compartments according to its phosphorylation state. Phosphorylation of HMGB1 was detected by metabolic labeling and Western blot analysis after treatments with TNF-alpha and okadaic acid, a phosphatase inhibitor. Hyper-phosphorylated HMGB1 in RAW 264.7 and human monocytes was relocated to the cytoplasm. In a nuclear import assay, phosphorylated HM4GB1 in the cytoplasm did not enter the nucleus. We mutated serine residues of either or both NLSs of HMGB1 to glutamic acid to simulate a phosphorylated state and examined the binding of HMGB1 to karyopherin-alpha 1, which was identified as the nuclear import protein for HMGB1 in this study. Substitution to glutamic acid in either NLSs decreased the binding with karyopherin-alpha 1 by similar to 50%; however, substitution of both NLSs showed no binding, and HMGB1 was relocated to the cytoplasm and subsequently secreted. These data support the hypothesis that HMGB1 could be phosphorylated and that the direction of transport is regulated by phosphorylation of both NLS regions.
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页码:7889 / 7897
页数:9
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