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Isolation of Viral Replication Compartment-enriched Sub-nuclear Fractions from Adenovirus-infected Normal Human Cells
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Preferential nuclear compartmentalization of endogenous mink cell focus-forming-related retroviral transcripts

M F Gourley1, A M Krieg, A D Steinberg

  • 1Cellular Immunology Section, National Institute of Arthritis, Musculoskeletal and Skin Disease, National Institutes of Health, Bethesda, Maryland 20892.

The Journal of Experimental Medicine
|May 1, 1990
PubMed

Insights

Endogenous mink cell focus-forming (MCF)-like retroviral transcripts show a nuclear predominance in thymoma cells. Their retroviral structure, not just size, influences this unique intracellular compartmentalization.

Area of Science:

  • Molecular Biology
  • Genomics
  • Retroviral Research

Background:

  • Endogenous retroviral sequences, like mink cell focus-forming (MCF)-like sequences in mice, are considered stable, inherited genetic elements.
  • These elements are generally presumed to be transcribed and translated similarly to other chromosomal genes.

Purpose of the Study:

  • To investigate the intracellular localization of endogenous MCF-like retroviral transcripts.
  • To determine if these transcripts exhibit a nuclear or cytoplasmic predominance in a specific cell line.

Main Methods:

  • Analysis of nuclear and cytoplasmic RNA distribution in the SL12.4 CD4-, CD8- thymoma cell line.
  • Quantification of full-length (8.4-kb) and spliced (3.0-kb) endogenous MCF-related transcripts.
  • Comparison with the distribution of other cellular transcripts, including c-myb.

Main Results:

  • A significant nuclear predominance of endogenous MCF-related transcripts was observed.
  • Both full-length and spliced MCF transcripts were predominantly nuclear, unlike typical cellular RNA which is largely cytoplasmic.
  • The nuclear localization could not be solely attributed to transcript size, as smaller MCF transcripts showed greater nuclear presence than similarly sized c-myb transcripts.

Conclusions:

  • Endogenous MCF-like retroviral transcripts exhibit unusual intracellular compartmentalization, favoring the nucleus.
  • The retroviral-like structure of these transcripts is suggested to play a key role in their nuclear retention.
  • This finding challenges the assumption of uniform gene expression for endogenous retroviral sequences.

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