DEAD box proteins, characterized by the conserved motif Asp-Glu-Ala-Asp (DEAD), are putative RNA helicases. They are implicated in a number of cellular processes involving alteration of RNA secondary structure such as translation initiation, nuclear and mitochondrial splicing, and ribosome and spliceosome assembly. Based on their distribution patterns, some members of this family are believed to be involved in embryogenesis, spermatogenesis, and cellular growth and division. This gene encodes a DEAD box protein, which interacts specifically with hepatitis C virus core protein resulting a change in intracellular location. This gene has a homolog located in the nonrecombining region of the Y chromosome. The protein sequence is 91% identical between this gene and the Y-linked homolog.[3]
Role in cancer
DDX3X is involved in many different types of cancer. For example, it is abnormally expressed in breast epithelial cancer cells in which its expression is activated by HIF1A during hypoxia.[4] Increased expression of DDX3X by HIF1A in hypoxia is initiated by the direct binding of HIF1A to the HIF1A response element,[4] as verified with chromatin immunoprecipitation and luciferase reporter assay. Since the expression of DDX3X is affected by the activity of HIF1A, the co-localization of these proteins has also been demonstrated in MDA-MB-231xenograft tumor samples.[4]
In HeLa cells DDX3X is reported to control cell cycle progression through Cyclin E1.[5] More specifically, DDX3X was shown to directly bind to the 5´ UTR of Cyclin E1 and thereby facilitating the translation of the protein. Increased protein levels of Cyclin E1 was demonstrated to mediate the transition of S phase entry.[5]
↑Park SH, Lee SG, Kim Y, Song K (Oct 1998). "Assignment of a human putative RNA helicase gene, DDX3, to human X chromosome bands p11.3→p11.23". Cytogenetics and Cell Genetics. 81 (3–4): 178–9. doi:10.1159/000015022. PMID9730595.
Li L, Li HS, Pauza CD, Bukrinsky M, Zhao RY (2006). "Roles of HIV-1 auxiliary proteins in viral pathogenesis and host-pathogen interactions". Cell Research. 15 (11–12): 923–34. doi:10.1038/sj.cr.7290370. PMID16354571.
Owsianka AM, Patel AH (May 1999). "Hepatitis C virus core protein interacts with a human DEAD box protein DDX3". Virology. 257 (2): 330–40. doi:10.1006/viro.1999.9659. PMID10329544.
Mamiya N, Worman HJ (May 1999). "Hepatitis C virus core protein binds to a DEAD box RNA helicase". The Journal of Biological Chemistry. 274 (22): 15751–6. doi:10.1074/jbc.274.22.15751. PMID10336476.
Kim YS, Lee SG, Park SH, Song K (October 2001). "Gene structure of the human DDX3 and chromosome mapping of its related sequences". Molecules and Cells. 12 (2): 209–14. PMID11710523.
Shu H, Chen S, Bi Q, Mumby M, Brekken DL (March 2004). "Identification of phosphoproteins and their phosphorylation sites in the WEHI-231 B lymphoma cell line". Molecular & Cellular Proteomics. 3 (3): 279–86. doi:10.1074/mcp.D300003-MCP200. PMID14729942.
Bouwmeester T, Bauch A, Ruffner H, Angrand PO, Bergamini G, Croughton K, Cruciat C, Eberhard D, Gagneur J, Ghidelli S, Hopf C, Huhse B, Mangano R, Michon AM, Schirle M, Schlegl J, Schwab M, Stein MA, Bauer A, Casari G, Drewes G, Gavin AC, Jackson DB, Joberty G, Neubauer G, Rick J, Kuster B, Superti-Furga G (February 2004). "A physical and functional map of the human TNF-alpha/NF-kappa B signal transduction pathway". Nature Cell Biology. 6 (2): 97–105. doi:10.1038/ncb1086. PMID14743216.
Yedavalli VS, Neuveut C, Chi YH, Kleiman L, Jeang KT (October 2004). "Requirement of DDX3 DEAD box RNA helicase for HIV-1 Rev-RRE export function". Cell. 119 (3): 381–92. doi:10.1016/j.cell.2004.09.029. PMID15507209.
Rush J, Moritz A, Lee KA, Guo A, Goss VL, Spek EJ, Zhang H, Zha XM, Polakiewicz RD, Comb MJ (January 2005). "Immunoaffinity profiling of tyrosine phosphorylation in cancer cells". Nature Biotechnology. 23 (1): 94–101. doi:10.1038/nbt1046. PMID15592455.
Tao WA, Wollscheid B, O'Brien R, Eng JK, Li XJ, Bodenmiller B, Watts JD, Hood L, Aebersold R (August 2005). "Quantitative phosphoproteome analysis using a dendrimer conjugation chemistry and tandem mass spectrometry". Nature Methods. 2 (8): 591–8. doi:10.1038/nmeth776. PMID16094384.
Gevaert K, Staes A, Van Damme J, De Groot S, Hugelier K, Demol H, Martens L, Goethals M, Vandekerckhove J (September 2005). "Global phosphoproteome analysis on human HepG2 hepatocytes using reversed-phase diagonal LC". Proteomics. 5 (14): 3589–99. doi:10.1002/pmic.200401217. PMID16097034.
Chang PC, Chi CW, Chau GY, Li FY, Tsai YH, Wu JC, Wu Lee YH (March 2006). "DDX3, a DEAD box RNA helicase, is deregulated in hepatitis virus-associated hepatocellular carcinoma and is involved in cell growth control". Oncogene. 25 (14): 1991–2003. doi:10.1038/sj.onc.1209239. PMID16301996.
