Simian virus 40 cRNA is processed into functional mRNA in microinjected monkey cells.

Area of Science:

• Molecular Biology
• Virology
• Cell Biology

Background:

• Simian virus 40 (SV40) is a DNA tumor virus.
• SV40 T-antigen is crucial for viral replication and oncogenesis.
• Understanding SV40 gene expression provides insights into eukaryotic gene regulation.

Purpose of the Study:

• To investigate the functional expression of in vitro synthesized SV40 cRNA in monkey cells.
• To determine the role of RNA splicing in SV40 T-antigen production.
• To elucidate the intracellular localization and requirements for SV40 mRNA processing and transport.

Main Methods:

• Microinjection of in vitro synthesized SV40 cRNA into monkey cells.
• Analysis of T-antigen production using immunoprecipitation and polyacrylamide gel electrophoresis.
• Enucleation of cells using cytochalasin B to study nuclear-dependent processes.
• Comparison of T-antigen synthesis after nuclear versus cytoplasmic injection of authentic mRNA.

Main Results:

• In vitro synthesized SV40 cRNA produced full-size T-antigen after microinjection.
• Polyadenylation of cRNA enhanced its biological activity, enabling T-antigen detection with as few as 50 injected cells.
• Splicing of cRNA was identified as a nuclear process, as enucleated cells failed to produce large T-antigen but synthesized small t-antigen.
• mRNA splicing was not essential for nuclear-to-cytoplasmic transport, as authentic T-antigen mRNA induced synthesis efficiently regardless of injection site.

Conclusions:

• SV40 cRNA can be functionally translated into T-antigen in monkey cells.
• RNA splicing is a necessary nuclear step for producing functional large T-antigen mRNA from early SV40 DNA.
• The transport of SV40 mRNA from the nucleus to the cytoplasm is independent of the splicing process.