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The LTR, v-src, LTR provirus generated in the mammalian genome by src mRNA reverse transcription and integration
1Department of Cellular and Viral Genetics, Institute of Molecular Genetics, Czechoslovak Academy of Sciences, Prague.
Abstract:
Different types of altered proviruses of Rous sarcoma virus (RSV) have been detected in mammalian tumor cell lines. We cloned and sequenced one of these altered proviruses with the structure LTR, v-src, LTR. The presence of an intact viral splice junction, as well as duplications of the chromosomal sequence GCGGGG flanking the two 2-base-pair-deleted LTRs, demonstrated reverse transcription and normal retroviral integration of src mRNA in mammalian cells. In addition, a 1-nucleotide deletion 2 bases upstream from the AAUAAA polyadenylation signal is suspected to be responsible for the absence of a poly(A) track in the src mRNA present in virions of rescued viruses.
Insights
Researchers identified an altered Rous sarcoma virus (RSV) provirus in mammalian tumor cells. This finding reveals normal retroviral integration of src mRNA and explains the absence of poly(A) in rescued virions.
Area of Science:
- Molecular Biology
- Virology
- Cancer Research
Background:
- Altered Rous sarcoma virus (RSV) proviruses have been observed in mammalian tumor cell lines.
- Understanding the structure and replication of these altered viruses is crucial for cancer research.
Purpose of the Study:
- To clone and sequence an altered RSV provirus from a mammalian tumor cell line.
- To elucidate the mechanism of retroviral integration and mRNA processing in mammalian cells.
Main Methods:
- Cloning and sequencing of the altered provirus.
- Analysis of viral splice junctions and flanking chromosomal sequences.
- Investigation of polyadenylation signal mutations.
Main Results:
- The altered provirus possessed a LTR-v-src-LTR structure.
- Evidence of reverse transcription and normal retroviral integration of src mRNA was found.
- A deletion near the polyadenylation signal likely caused the absence of a poly(A) track in src mRNA.
Conclusions:
- Mammalian cells can support normal retroviral integration of RSV src mRNA.
- A specific deletion mutation affects polyadenylation of src mRNA in rescued viruses.