The region of mouse mammary tumor virus DNA containing the long terminal repeat includes a long coding sequence and signals for hormonally regulated transcription.

Abstract

Starting from a biologically active recombinant DNA clone of exogenous unintegrated GR mouse mammary tumor virus, we have generated three subclones of PstI fragments of 1.45, 1.1, and 2.0 kb in the plasmid vector PBR322. The nucleotide sequence has been determined for the clone of 1.45 kb which includes almost the complete region of the long terminal repeat (LTR) plus an adjacent stretch of unique sequence DNA. A short region of the 2.0 kb clone, containing the beginning of the LTR, has also been sequenced. Starting with the A of an initiation codon outside the LTR, we detected an open reading frame of 960 nucleotides, potentially coding for a protein of 320 amino acids (36K). Two hundred nucleotides downstream from the termination codon, and approximately 25 nucleotides upstream from the presumptive initiation site of viral RNA synthesis, we found a promoter‐like sequence. The sequence AGTAAA was detected approximately 15‐20 nucleotides upstream from the 3′ end of virion RNA and probably serves as a polyadenylation signal. The 1.45 kb PstI fragment has been transfected into Ltk‐ cells together with a plasmid containing the thymidine kinase gene of herpes simplex virus. The virus‐specific RNA synthesis detected in a Tk+ cell clone was strongly stimulated by the addition of dexamethasone.

Control of gene expression by glucocorticoid hormones

“…dine kinase (tk)-deficient mouse fibroblasts (tk-L cells) with cloned viral DNA allowed a definition of the glucocorticoid-sensitive viral DNA regions to be made. In these experiments, unintegrated viral DNA from infected hepatoma cells (Buetti & Diggelman, 1981) or proviral DNA from a mouse library (Hynes et al, 1981b) (Fasel et al, 1982). The LTR contains the viral transcription initiation site (Fig.…”

Dual function of a nuclear factor I binding site in MMTV transcription regulation

“…The hormone-responsive sequences are located in the long terminal repeat (LTR) of the provirus (4,5,6,7), in a region of approximately 200 bp upstream of the transcription start site (8,9,10). While steroids like progestins and androgens have recently been shown to also affect MMTV transcription in mammary cells (11,12,13,14,15), it is the response to glucocorticoids in cultured fibroblasts that has been studied in greatest detail (16,17,18,19).…”

Proteins Antigenically Related to Peptides Encoded by the Mouse Mammary Tumour Virus Long Terminal Repeat Sequence Are Associated with Intracytoplasmic A Particles

“…These tests demonstrated that anti-LTR II, anti-LTR 23, anti-CAP 18-12 and anti-MMTV p27 all recognize epitopes in disrupted CAP. Significantly, the synthetic peptide used by Fasel et al (1982) to raise anti-LTR 23 contains the entire amino acid sequence of our peptide II in its N-terminal domain.…”

“…Serum samples were obtained 10 to 14 days after the last immunizaiton. An additional LTR ORF antiserum raised against a 23 amino acid synthetic peptide was kindly supplied by Dr H. Diggelmann (Fasel et al, 1982).…”

“…Peptides representing reading frames (I) 772 to 798, (II) 829 to 852 and (III) 799 to 819 of the LTR (Fasel et al, 1982) were synthesized. These peptides have the following amino acid sequences: (I) Tyr-Arg-Ser-Leu-Pro-Phe-Arg-Glu-Arg; (II) Leu-Thr-Glu-Lys-Glu-Lys-Asp-Asp; (III) Leu-Ala-Arg-Ala-Arg-Pro-Pro.…”