RNA-binding Motif Protein 15 Binds to the RNA Transport Element RTE and Provides a Direct Link to the NXF1 Export Pathway*

Retroviruses/retroelements provide tools enabling the identification and dissection of basic steps for post-transcriptional regulation of cellular mRNAs. The RNA transport element (RTE) identified in mouse retrotransposons is functionally equivalent to constitutive transport element of Type D retroviruses, yet does not bind directly to the mRNA export receptor NXF1. Here, we report that the RNA-binding motif protein 15 (RBM15) recognizes RTE directly and specifically in vitro and stimulates export and expression of RTE-containing reporter mRNAs in vivo. Tethering of RBM15 to a reporter mRNA showed that RBM15 acts by promoting mRNA export from the nucleus. We also found that RBM15 binds to NXF1 and the two proteins cooperate in stimulating RTE-mediated mRNA export and expression. Thus, RBM15 is a novel mRNA export factor and is part of the NXF1 pathway. We propose that RTE evolved as a high affinity RBM15 ligand to provide a splicing-independent link to NXF1, thereby ensuring efficient nuclear export and expression of retrotransposon transcripts.

[1]  G. Pavlakis,et al.  RTE and CTE mRNA export elements synergistically increase expression of unstable, Rev-dependent HIV and SIV mRNAs , 2006, Retrovirology.

[2]  O. Bernard,et al.  Interaction of the Epstein-Barr Virus mRNA Export Factor EB2 with Human Spen Proteins SHARP, OTT1, and a Novel Member of the Family, OTT3, Links Spen Proteins with Splicing Regulation and mRNA Export* , 2005, Journal of Biological Chemistry.

[3]  G. Ruthel,et al.  Nuclear Export Factor Family Protein Participates in Cytoplasmic mRNA Trafficking* , 2005, Journal of Biological Chemistry.

[4]  S. Morris,et al.  RBM15 and MKL1 mutational screening in megakaryoblastic leukemia cell lines and clinical samples , 2005, Leukemia.

[5]  W. Tan,et al.  Identification and characterization of the mouse nuclear export factor (Nxf) family members , 2005, Nucleic acids research.

[6]  Ming-Yu Yang,et al.  RBM15‐MKL1 (OTT‐MAL) fusion transcript in an adult acute myeloid leukemia patient , 2005, American journal of hematology.

[7]  Y. Yoneda,et al.  Molecular cloning and functional characterization of mouse Nxf family gene products. , 2005, Genomics.

[8]  J. Steitz,et al.  SRprises along a messenger's journey. , 2005, Molecular cell.

[9]  G. Pavlakis,et al.  Structural and Functional Analysis of the RNA Transport Element, a Member of an Extensive Family Present in the Mouse Genome , 2005, Journal of Virology.

[10]  G. Panayotou,et al.  Identification of growth factor-regulated proteins using 2D electrophoresis and mass spectrometry , 2005, Growth factors.

[11]  M. Lai,et al.  Hypophosphorylated ASF/SF2 Binds TAP and Is Present in Messenger Ribonucleoproteins* , 2004, Journal of Biological Chemistry.

[12]  J. Steitz,et al.  A molecular link between SR protein dephosphorylation and mRNA export. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[13]  M. Moore,et al.  The ever-increasing complexities of the exon junction complex. , 2004, Current opinion in cell biology.

[14]  Francis Harper,et al.  Identification of autonomous IAP LTR retrotransposons mobile in mammalian cells , 2004, Nature Genetics.

[15]  M. Hammarskjöld,et al.  Tap and NXT promote translation of unspliced mRNA. , 2003, Genes & development.

[16]  B. Cullen,et al.  Exon junction complexes mediate the enhancing effect of splicing on mRNA expression , 2003, Proceedings of the National Academy of Sciences of the United States of America.

[17]  S. Morris,et al.  Megakaryoblastic Leukemia 1, a Potent Transcriptional Coactivator for Serum Response Factor (SRF), Is Required for Serum Induction of SRF Target Genes , 2003, Molecular and Cellular Biology.

[18]  I. Shatsky,et al.  PSF Acts through the Human Immunodeficiency Virus Type 1 mRNA Instability Elements To Regulate Virus Expression , 2003, Molecular and Cellular Biology.

[19]  Mariko Ariyoshi,et al.  A conserved structural motif reveals the essential transcriptional repression function of Spen proteins and their role in developmental signaling. , 2003, Genes & development.

[20]  E. Izaurralde,et al.  The interplay of nuclear mRNP assembly, mRNA surveillance and export. , 2003, Trends in cell biology.

[21]  R. Reed,et al.  Coupling transcription, splicing and mRNA export. , 2003, Current opinion in cell biology.

[22]  E. Izaurralde,et al.  Genome‐wide analysis of nuclear mRNA export pathways in Drosophila , 2003, The EMBO journal.

[23]  Horst Hameister,et al.  SHARP is a novel component of the Notch/RBP‐Jκ signalling pathway , 2002 .

[24]  G. Dreyfuss,et al.  Messenger-RNA-binding proteins and the messages they carry , 2002, Nature Reviews Molecular Cell Biology.

[25]  J. Kjems,et al.  An element in the 3' untranslated region of human LINE-1 retrotransposon mRNA binds NXF1(TAP) and can function as a nuclear export element. , 2002, RNA.

[26]  W. Tan,et al.  U2AF Participates in the Binding of TAP (NXF1) to mRNA* , 2002, The Journal of Biological Chemistry.

[27]  R. Berger,et al.  Recurrence of OTT–MAL fusion in t(1;22) of infant AML‐M7 , 2002, Genes, chromosomes & cancer.

[28]  B. E. Black,et al.  RNA Export Mediated by Tap Involves NXT1-dependent Interactions with the Nuclear Pore Complex* , 2001, The Journal of Biological Chemistry.

[29]  M. Rosbash,et al.  The DECD box putative ATPase Sub2p is an early mRNA export factor , 2001, Current Biology.

[30]  T. Köcher,et al.  The DExH/D box protein HEL/UAP56 is essential for mRNA nuclear export in Drosophila , 2001, Current Biology.

[31]  M. Mann,et al.  Pre-mRNA splicing and mRNA export linked by direct interactions between UAP56 and Aly , 2001, Nature.

[32]  H. Le Hir,et al.  The exon–exon junction complex provides a binding platform for factors involved in mRNA export and nonsense‐mediated mRNA decay , 2001, The EMBO journal.

[33]  F. Wong-Staal,et al.  Mapping the Functional Domains of HAP95, a Protein That Binds RNA Helicase A and Activates the Constitutive Transport Element of Type D Retroviruses* , 2001, The Journal of Biological Chemistry.

[34]  Dean Nizetic,et al.  Fusion of two novel genes, RBM15 and MKL1, in the t(1;22)(p13;q13) of acute megakaryoblastic leukemia , 2001, Nature Genetics.

[35]  M. Rode,et al.  Overexpression of TAP/p15 Heterodimers Bypasses Nuclear Retention and Stimulates Nuclear mRNA Export* , 2001, The Journal of Biological Chemistry.

[36]  F. Nappi,et al.  Identification of a Novel Posttranscriptional Regulatory Element by Using a rev- and RRE-Mutated Human Immunodeficiency Virus Type 1 DNA Proviral Clone as a Molecular Trap , 2001, Journal of Virology.

[37]  Nicole Dastugue,et al.  Involvement of a human gene related to the Drosophila spen gene in the recurrent t(1;22) translocation of acute megakaryocytic leukemia , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[38]  R. Evans,et al.  Sharp, an inducible cofactor that integrates nuclear receptor repression and activation. , 2001, Genes & development.

[39]  J. Steitz,et al.  Splicing factors SRp20 and 9G8 promote the nucleocytoplasmic export of mRNA. , 2001, Molecular cell.

[40]  B. E. Black,et al.  NXT1 (p15) Is a Crucial Cellular Cofactor in TAP-Dependent Export of Intron-Containing RNA in Mammalian Cells , 2001, Molecular and Cellular Biology.

[41]  H. Le Hir,et al.  The spliceosome deposits multiple proteins 20–24 nucleotides upstream of mRNA exon–exon junctions , 2000, The EMBO journal.

[42]  M. Suyama,et al.  TAP (NXF1) Belongs to a Multigene Family of Putative RNA Export Factors with a Conserved Modular Architecture , 2000, Molecular and Cellular Biology.

[43]  W. Tan,et al.  The mRNA export in Caenorhabditis elegans is mediated by Ce-NXF-1, an ortholog of human TAP/NXF and Saccharomyces cerevisiae Mex67p. , 2000, RNA.

[44]  F. Wong-Staal,et al.  Specific Interaction between RNA Helicase A and Tap, Two Cellular Proteins That Bind to the Constitutive Transport Element of Type D Retrovirus* , 2000, The Journal of Biological Chemistry.

[45]  E. Hurt,et al.  The protein Aly links pre-messenger-RNA splicing to nuclear export in metazoans , 2000, Nature.

[46]  F. Wong-Staal,et al.  Sam68, RNA helicase A and Tap cooperate in the post-transcriptional regulation of human immunodeficiency virus and type D retroviral mRNA , 2000, Oncogene.

[47]  R. Reed,et al.  Splicing is required for rapid and efficient mRNA export in metazoans. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[48]  E. Hudson,et al.  Identification of Novel Import and Export Signals of Human TAP, the Protein That Binds to the Constitutive Transport Element of the Type D Retrovirus mRNAs , 1999, Molecular and Cellular Biology.

[49]  E. Izaurralde,et al.  TAP binds to the constitutive transport element (CTE) through a novel RNA‐binding motif that is sufficient to promote CTE‐dependent RNA export from the nucleus , 1999, The EMBO journal.

[50]  T. Hope,et al.  Leptomycin B Inhibits Equine Infectious Anemia Virus Rev and Feline Immunodeficiency Virus Rev Function but Not the Function of the Hepatitis B Virus Posttranscriptional Regulatory Element , 1998, Journal of Virology.

[51]  M. Wilm,et al.  TAP, the human homolog of Mex67p, mediates CTE-dependent RNA export from the nucleus. , 1998, Molecular cell.

[52]  E. Hudson,et al.  Development and applications of enhanced green fluorescent protein mutants. , 1998, BioTechniques.

[53]  A. Pasquinelli,et al.  The constitutive transport element (CTE) of Mason–Pfizer monkey virus (MPMV) accesses a cellular mRNA export pathway , 1997, The EMBO journal.

[54]  C. Saavedra,et al.  The simian retrovirus-1 constitutive transport element, unlike the HIV-1 RRE, uses factors required for cellular mRNA export , 1997, Current Biology.

[55]  M. Hammarskjöld,et al.  The effect of viral regulatory protein expression on gene delivery by human immunodeficiency virus type 1 vectors produced in stable packaging cell lines , 1997, Journal of virology.

[56]  J. Valcárcel,et al.  U2AF65 recruits a novel human DEAD box protein required for the U2 snRNP-branchpoint interaction. , 1997, Genes & development.

[57]  R. Lührmann,et al.  Mex67p, a novel factor for nuclear mRNA export, binds to both poly(A)+ RNA and nuclear pores , 1997, The EMBO journal.

[58]  A. Zolotukhin,et al.  Mutations in the Nuclear Export Signal of Human Ran-binding Protein RanBP1 Block the Rev-mediated Posttranscriptional Regulation of Human Immunodeficiency Virus Type 1* , 1997, The Journal of Biological Chemistry.

[59]  F. Wong-Staal,et al.  Identification and purification of cellular proteins that specifically interact with the RNA constitutive transport elements from retrovirus D. , 1997, Virology.

[60]  M. Hammarskjöld,et al.  A structured retroviral RNA element that mediates nucleocytoplasmic export of intron-containing RNA , 1997, Molecular and cellular biology.

[61]  G. Karsenty,et al.  Identification of an RNA sequence within an intracisternal-A particle element able to replace Rev-mediated posttranscriptional regulation of human immunodeficiency virus type 1 , 1997, Journal of virology.

[62]  G. Pavlakis,et al.  The posttranscriptional control element of the simian retrovirus type 1 forms an extensive RNA secondary structure necessary for its function , 1996, Journal of virology.

[63]  G. Pavlakis,et al.  Continuous propagation of RRE(-) and Rev(-)RRE(-) human immunodeficiency virus type 1 molecular clones containing a cis-acting element of simian retrovirus type 1 in human peripheral blood lymphocytes , 1994, Journal of virology.

[64]  W. Boelens,et al.  Nuclear export of different classes of RNA is mediated by specific factors , 1994, The Journal of cell biology.

[65]  K. Jeang,et al.  A small element from the Mason-Pfizer monkey virus genome makes human immunodeficiency virus type 1 expression and replication Rev-independent. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[66]  D. McDonald,et al.  Posttranscriptional regulation by the human immunodeficiency virus type 1 Rev and human T-cell leukemia virus type I Rex proteins through a heterologous RNA binding site , 1992, Journal of virology.

[67]  D. McDonald,et al.  Minimal Rev-response element for type 1 human immunodeficiency virus , 1991, Journal of virology.

[68]  M. Hammarskjöld,et al.  Regulation of human immunodeficiency virus env expression by the rev gene product , 1989, Journal of virology.

[69]  S. Le,et al.  The HIV-1 rev trans-activator acts through a structured target sequence to activate nuclear export of unspliced viral mRNA , 1989, Nature.

[70]  T. Copeland,et al.  rev protein of human immunodeficiency virus type 1 affects the stability and transport of the viral mRNA. , 1989, Proceedings of the National Academy of Sciences of the United States of America.

[71]  B. Cullen,et al.  Secreted placental alkaline phosphatase: a powerful new quantitative indicator of gene expression in eukaryotic cells. , 1988, Gene.

[72]  K. Wood,et al.  Firefly luciferase gene: structure and expression in mammalian cells , 1987, Molecular and cellular biology.

[73]  N. Nomura,et al.  Complete sequencing and characterization of 21,243 full-length human cDNAs , 2004, Nature Genetics.

[74]  E. Izaurralde.  Nuclear export of messenger RNA. , 2002, Results and problems in cell differentiation.

[75]  M. Hentze,et al.  Tethered-function analysis reveals that elF4E can recruit ribosomes independent of its binding to the cap structure. , 2001, RNA.

[76]  U. Hellman,et al.  Improvement of an "In-Gel" digestion procedure for the micropreparation of internal protein fragments for amino acid sequencing. , 1995, Analytical biochemistry.