cis-active elements from mouse chromosomal DNA suppress simian virus 40 DNA replication

Area of Science:

• Molecular Biology
• Virology
• Cell Biology

Background:

• Simian virus 40 (SV40) is a well-characterized DNA tumor virus.
• Understanding host-virus interactions is crucial for controlling viral replication.

Purpose of the Study:

• To investigate the role of cellular DNA sequences in regulating SV40 replication.
• To identify specific cellular DNA fragments that can suppress SV40 replication.

Main Methods:

• Fusion of SV40-transformed cells with permissive cells to rescue SV40 DNA.
• Cloning and characterization of rescued SV40 DNA and associated mouse DNA fragments.
• Sequencing of mouse DNA fragments.
• Transfection of rat cells with SV40 DNA constructs containing or lacking mouse DNA fragments.
• Analysis of SV40 replication and T antigen/p53 expression in transformed cells.

Main Results:

• A 2-kilobase mouse DNA fragment associated with SV40 DNA was identified and sequenced.
• Insertion of this mouse DNA fragment or its sub-fragments into SV40 plasmid DNA suppressed replication in monkey cells.
• Rat cells transformed with SV40 DNA linked to these mouse DNA fragments showed reduced SV40 DNA replication after fusion with permissive cells compared to controls.
• Suppression of SV40 replication occurred in cis, irrespective of whether SV40 DNA was in plasmid or integrated chromosomal form.

Conclusions:

• Two independent segments of cellular DNA possess the ability to suppress SV40 replication in vivo.
• These cellular DNA segments act in cis to inhibit SV40 replication, independent of T antigen and p53 expression levels.