The Solitary Long Terminal Repeats of ERV-9 Endogenous Retrovirus Are Conserved during Primate Evolution and Possess Enhancer Activities in Embryonic and Hematopoietic Cells

ABSTRACT The solitary long terminal repeats (LTRs) of ERV-9 endogenous retrovirus contain the U3, R, and U5 regions but no internal viral genes. They are middle repetitive DNAs present at 2,000 to 4,000 copies in primate genomes. Sequence analyses of the 5" boundary area of the erythroid β-globin locus control region (β-LCR) and the intron of the embryonic axin gene show that a solitary ERV-9 LTR has been stably integrated in the respective loci for at least 15 million years in the higher primates from orangutan to human. Functional studies utilizing the green fluorescent protein (GFP) gene as the reporter in transfection experiments show that the U3 region of the LTRs possesses strong enhancer activity in embryonic cells of widely different tissue origins and in adult cells of blood lineages. In both the genomic LTRs of embryonic placental cells and erythroid K562 cells and transfected LTRs of recombinant GFP plasmids in K562 cells, the U3 enhancer activates synthesis of RNAs that are initiated from a specific site 25 bases downstream of the AATAAA (TATA) motif in the U3 promoter. A second AATAAA motif in the R region does not serve as the TATA box or as the polyadenylation signal. The LTR-initiated RNAs extend through the R and U5 regions into the downstream genomic DNA. The results suggest that the ERV-9 LTR-initiated transcription process may modulate transcription of the associated gene loci in embryonic and hematopoietic cells.

[1]  N. Proudfoot,et al.  Poly(A) site selection in the HIV-1 provirus: inhibition of promoter-proximal polyadenylation by the downstream major splice donor site. , 1995, Genes & development.

[2]  J. Stavenhagen,et al.  An ancient provirus has imposed androgen regulation on the adjacent mouse sex-limited protein gene , 1988, Cell.

[3]  R. Kurth,et al.  The viruses in all of us: characteristics and biological significance of human endogenous retrovirus sequences. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[4]  M. Wickens,et al.  The C-terminal domain of RNA polymerase II couples mRNA processing to transcription , 1997, Nature.

[5]  A. Wickrema,et al.  Differentiation and erythropoietin receptor gene expression in human erythroid progenitor cells. , 1992, Blood.

[6]  Z. Werb,et al.  Implantation and the placenta: key pieces of the development puzzle. , 1994, Science.

[7]  L. Hood,et al.  Gene families: the taxonomy of protein paralogs and chimeras. , 1997, Science.

[8]  J. Licht,et al.  Transcription factors, normal myeloid development, and leukemia. , 1997, Blood.

[9]  D. Tuan,et al.  An erythroid-specific, developmental-stage-independent enhancer far upstream of the human "beta-like globin" genes. , 1989, Proceedings of the National Academy of Sciences of the United States of America.

[10]  T. Vasicek,et al.  Two dominant mutations in the mouse fused gene are the result of transposon insertions. , 1997, Genetics.

[11]  D. Tuan,et al.  Transcription of the HS2 enhancer toward a cis-linked gene is independent of the orientation, position, and distance of the enhancer relative to the gene , 1997, Molecular and cellular biology.

[12]  A. Wellstein,et al.  Human trophoblast and choriocarcinoma expression of the growth factor pleiotrophin attributable to germ-line insertion of an endogenous retrovirus. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[13]  M. Strazzullo,et al.  Mobilization of an ERV9 human endogenous retroviral element during primate evolution. , 1995, Virology.

[14]  D. Tuan,et al.  Transcription of the hypersensitive site HS2 enhancer in erythroid cells. , 1992, Proceedings of the National Academy of Sciences of the United States of America.

[15]  S. Orkin,et al.  The transcriptional control of hematopoiesis. , 1996, Blood.

[16]  H. Temin.  Structure, variation and synthesis of retrovirus long terminal repeat , 1981, Cell.

[17]  A. Smit,et al.  The origin of interspersed repeats in the human genome. , 1996, Current opinion in genetics & development.

[18]  D. Mager,et al.  Strategy for detecting cellular transcripts promoted by human endogenous long terminal repeats: identification of a novel gene (CDC4L) with homology to yeast CDC4. , 1992, Genomics.

[19]  D. Tuan,et al.  Modulatory subdomains of the HS2 enhancer differentially regulate enhancer activity in erythroid cells at different developmental stages. , 1997, Blood cells, molecules & diseases.

[20]  D. Tuan,et al.  The "beta-like-globin" gene domain in human erythroid cells. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[21]  M. Rocchi,et al.  Characterization and genomic mapping of chimeric ERV9 endogenous retroviruses-host gene transcripts. , 1998, Gene.

[22]  C. Groves,et al.  Toward a phylogenetic classification of Primates based on DNA evidence complemented by fossil evidence. , 1998, Molecular phylogenetics and evolution.

[23]  D. Mager,et al.  Endogenous Human Retroviruses , 1994 .

[24]  D. Schlessinger,et al.  Distribution of moderately repetitive sequences pTR5 and LF1 in Xq24-q28 human DNA and their use in assembling YAC contigs. , 1992, Genomics.

[25]  A. Simeone,et al.  Identification and characterization of novel human endogenous retroviral sequences prefentially expressed in undifferentiated embryonal carcinoma cells. , 1991, Nucleic acids research.

[26]  W. Doolittle,et al.  Selfish genes, the phenotype paradigm and genome evolution , 1980, Nature.

[27]  H. Ashe,et al.  Intergenic transcription and transinduction of the human beta-globin locus. , 1997, Genes & development.

[28]  M. Frohman,et al.  Rapid amplification of complementary DNA ends for generation of full-length complementary DNAs: thermal RACE. , 1993, Methods in enzymology.

[29]  W Miller,et al.  Locus control regions of mammalian beta-globin gene clusters: combining phylogenetic analyses and experimental results to gain functional insights. , 1997, Gene.

[30]  D. Tuan,et al.  A long terminal repeat of the human endogenous retrovirus ERV-9 is located in the 5' boundary area of the human beta-globin locus control region. , 1998, Genomics.

[31]  J. Bieker,et al.  A novel, erythroid cell-specific murine transcription factor that binds to the CACCC element and is related to the Krüppel family of nuclear proteins , 1993, Molecular and cellular biology.

[32]  R. Christy,et al.  Functional analysis of the long terminal repeats of intracisternal A-particle genes: sequences within the U3 region determine both the efficiency and direction of promoter activity , 1988, Molecular and cellular biology.

[33]  D. Mager,et al.  A gene deletion ending within a complex array of repeated sequences 3' to the human beta-globin gene cluster. , 1986, Proceedings of the National Academy of Sciences of the United States of America.

[34]  M. Meisler,et al.  Endogenous retroviral sequences are required for tissue-specific expression of a human salivary amylase gene. , 1992, Genes & development.

[35]  H. Fan.  Retroviruses and Their Role in Cancer , 1994 .

[36]  P. Tiollais,et al.  Localization of Streptomyces stanfordii endonuclease I (SstI) cleavage sites on genomes of human adenovirus types two and five. , 1979, Gene.