期刊
JOURNAL OF CELLULAR BIOCHEMISTRY
卷 113, 期 3, 页码 985-996出版社
WILEY
DOI: 10.1002/jcb.23428
关键词
DEAD-BOX; DDX3; DDX5; PHOSPHORYLATION; PROTEIN-PROTEIN INTERACTION; mRNP EXPORT
资金
- Korea Science & Engineering Foundation [R04-2003-000-10126-0]
- National Research Foundation of Korea (NRF) [2011-0018393]
- Korea Science & Engineering Foundation, Republic of Korea [R04-2003-000-10126-0]
- Ministry of Education, Science, and Technology [2011-0018393]
- National Research Foundation of Korea [2010-0020141] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
DDX3 is involved in RNA transport, translational control, proliferation of RNA viruses, and cancer progression. From yeast two-hybrid screening using the C-terminal region of DDX3 as a bait, the DEAD-box RNA helicase DDX5 was cloned. In immunofluorescence analysis, DDX3 and DDX5 were mainly co-localized in the cytoplasm. Interestingly, cytoplasmic levels of DDX5 increased in the G2/M phase and consequently proteinprotein interaction also increased in the cytoplasmic fraction. DDX3 was highly phosphorylated at its serine, threonine, and tyrosine residues in the steady state, but not phosphorylated at the serine residue(s) in the G2/M phase. DDX5 was less phosphorylated in the G1/S phase; however, it was highly phosphorylated at serine, threonine, and tyrosine residues in the G2/M phase. PP2A treatment of the cytoplasmic lysate from G2/M phase cells positively affected the interaction between DDX3 and DDX5, whereas, PTP1B treatment did not. In an analysis involving recombinant His-DDX3 and His-DDX5, PP2A pretreatment of His-DDX5 increased the interaction with endogenous DDX3, and vice versa. Furthermore, the results of GST pull-down experiments support the conclusion that dephosphorylation of serine and/or threonine residues in both proteins enhanced proteinprotein interactions. UV cross-linking experiments showed that DDX3 and DDX5 are involved in mRNP export. Additionally, DDX3 knockdown blocked the shuttling of DDX5 to the nucleus. These data demonstrate a novel interaction between DDX3 and DDX5 through the phosphorylation of both proteins, especially in the G2/M phase, and suggest a novel combined mechanism of action, involving RNP remodeling and splicing, for DEAD-box RNA helicases involved in mRNP export. J. Cell. Biochem. 113: 985996, 2012. (C) 2011 Wiley Periodicals, Inc.
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