Evidence for a new form of retroviral env transcript in leukemic and normal mouse lymphoid cells.
Murine leukemia virus-related RNA species were examined in a set of radiation-induced T-cell leukemias from BALB/c mice. No evidence was found for linkage of viral long terminal repeat-derived (U5) sequences to information of host origin. A novel class of 2-kilobase (kb) env-related transcripts, about 1kb shorter than normal viral env messenger, was found in all the leukemias. All of the 2-kb transcripts contained sequences homologous to the xenotropic virus-related env sequences in the Friend spleen focus-forming virus, representing the N-terminal portion of gp70. In two of the leukemias, these transcripts were found to contain both ecotropic p15E and U3 sequences in addition to the xenotropic gp70-related sequence. These two leukemias, but not others in which ecotropic sequences were absent from the 2-kb RNA, harbored several copies of a specific class of env recombinant proviruses. These proviruses possessed full-size env genes and were submethylated, as shown by SmaI and XmaI digests of proviral DNA. Low levels of 2-kb RNA were found in normal thymocytes from strains BALB/c, AKR, and 129 but not from congenic 129 GIX- mice. It is possible that the 2-kb RNA may originate by a novel splicing step that removes portions of the gp70 and p15E sequences from full-length env transcripts.
D000818:Animals; D002460:Cell Line; D009052:Leukemia Virus, Murine / Q000235:genetics*; D007953:Leukemia, Radiation-Induced / Q000382:microbiology*; D051379:Mice; D008806:Mice, Inbred AKR; D008807:Mice, Inbred BALB C; D009693:Nucleic Acid Hybridization; D011061:Poly A / Q000032:analysis / Q000235:genetics; D012313:RNA / Q000032:analysis / Q000235:genetics; D012326:RNA Splicing; D012333:RNA, Messenger; D012367:RNA, Viral / Q000032:analysis / Q000235:genetics*; D011995:Recombination, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D013601:T-Lymphocytes / Q000032:analysis; D014158:Transcription, Genetic; D014759:Viral Envelope Proteins; D014764:Viral Proteins / Q000235:genetics*
D012333:RNA, Messenger; D012367:RNA, Viral; D014759:Viral Envelope Proteins; D014764:Viral Proteins; D011061:Poly A; D012313:RNA