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Structural analysis of a 1.7-kilobase mouse mammary tumor virus-specific RNA
Abstract:
We have detected a mouse mammary tumor virus (MMTV)-specific 1.7-kilobase (kb) polyadenylated RNA in mammary glands of several mouse strains. In BALB/c mice, it is the only MMTV-specific RNA species present. C3H and GR mammary glands and tumors contain, in addition, 3.8- and 7.8-kb MMTV RNAs. Nuclease S1 analysis was performed to map 1.7-kb polyadenylated RNA. It contains predominantly long terminal repeat (LTR) sequences. The 5' end maps approximately 134 nucleotides upstream from the 3' end of the LTR. Colinearity with complete proviral DNA continues to a site about 153 nucleotides downstream from the left (5') LTR. No sequences from the middle part of proviral DNA were found. Colinearity with proviral DNA is resumed 72 nucleotides upstream from the right (3') LTR. The nucleotide sequence in this area is TTCCAGT, which is a splice acceptor consensus sequence. The anatomy of 1.7-kb RNA indicates that it may serve as a messenger for the 36,700-dalton protein encoded by the LTRs of MMTV.
Insights
Researchers identified a specific 1.7-kilobase RNA in mouse mammary glands, predominantly containing long terminal repeat sequences. This RNA may function as a messenger for a protein encoded by the mouse mammary tumor virus (MMTV) long terminal repeats.
Area of Science:
- Virology
- Molecular Biology
- Genomics
Background:
- Mouse mammary tumor virus (MMTV) is associated with mammary tumors in mice.
- Different mouse strains exhibit varying MMTV RNA profiles in mammary tissues.
Purpose of the Study:
- To characterize the MMTV-specific 1.7-kilobase (kb) polyadenylated RNA found in mouse mammary glands.
- To determine the molecular structure and potential function of this RNA species.
Main Methods:
- Detection and characterization of MMTV-specific RNA using molecular hybridization techniques.
- Nuclease S1 analysis to precisely map the RNA's structure.
- Comparison of RNA sequences with MMTV proviral DNA.
Main Results:
- A 1.7-kb MMTV-specific RNA was detected in multiple mouse strains, being the sole species in BALB/c mice.
- Nuclease S1 mapping revealed that the 1.7-kb RNA primarily consists of long terminal repeat (LTR) sequences.
- The RNA sequence includes a splice acceptor site, suggesting a specific transcriptional or post-transcriptional processing event.
Conclusions:
- The 1.7-kb RNA's structure, rich in LTR sequences and containing a splice acceptor site, suggests it is a distinct MMTV transcript.
- This RNA may function as a messenger RNA (mRNA) encoding a protein of approximately 36,700 daltons, potentially translated from the MMTV LTR sequences.