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Characterization of human endogenous retroviral envelope RNA transcripts
Journal of Virology
|October 1, 1985
Summary
Researchers analyzed human endogenous retroviral env RNA transcripts, finding two main sizes (3.0 and 1.7 kb) in cancer cells. Neither RNA size could produce full-length env proteins due to premature stop codons.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Human endogenous retroviruses (HERVs) are remnants of ancient retroviral infections integrated into the human genome.
- HERV env proteins are crucial for retroviral structure and function, but their expression and processing in humans are not fully understood.
- Aberrant expression of HERV transcripts has been linked to various diseases, including cancers.
Purpose of the Study:
- To characterize the structure and coding potential of human endogenous retroviral (HERV) env RNA transcripts.
- To investigate the presence and size variations of HERV env RNAs in different human cell types, including cancerous tissues.
- To determine if these HERV env RNA transcripts can encode full-length functional env proteins.
Main Methods:
- Northern blot hybridization was employed to detect and size HERV env RNA transcripts.
- Complementary DNA (cDNA) cloning was used to obtain partial sequences of the identified RNA species.
- Sequence analysis was performed to identify coding regions and potential protein products.
Main Results:
- Polyadenylated 3.0-kilobase (kb) and 1.7-kb HERV env RNA transcripts were detected in placenta, colon carcinoma, and breast carcinoma cells.
- Partial cDNA clones of both 3.0-kb and 1.7-kb env RNAs were obtained.
- Both RNA species contained sequences coding for putative gp70, a component of the retroviral envelope.
- The 1.7-kb env RNA lacked sequences necessary for a p15E analog, a different envelope component.
- Both cDNA clones revealed in-frame termination codons, preventing the synthesis of full-length env proteins.
Conclusions:
- Human endogenous retroviral env RNA transcripts exist in multiple size forms in various human tissues, including tumors.
- The characterized HERV env RNAs possess partial coding capacity but are incapable of producing full-length env proteins due to premature termination signals.
- These findings suggest post-transcriptional or post-translational regulation mechanisms may control HERV env protein expression in humans.