Transfected DNA is mutated in monkey, mouse, and human cells.

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Mammalian cells are widely used for gene expression studies.
• Understanding the genetic stability of transfected DNA is crucial for accurate research outcomes.

Purpose of the Study:

• To investigate the mutation frequency of bacterial genes within shuttle vectors after transfection into various mammalian cell lines.
• To determine the timing and requirements for mutagenesis during DNA transfection.

Main Methods:

• Utilized papovavirus-based shuttle vectors containing the bacterial lacI gene.
• Transfected vectors into multiple mammalian cell lines (simian, mouse, human).
• Analyzed mutation frequency, types (base substitutions, deletions, insertions), and timing post-transfection.

Main Results:

• Achieved a mutation frequency of approximately 1% in the lacI gene, four orders of magnitude higher than spontaneous rates.
• Observed mutations including base substitutions, deletions, and insertions from the host genome.
• Mutagenesis occurred rapidly after DNA nuclear entry and did not require vector replication.

Conclusions:

• DNA transfection into mammalian cells inherently leads to a high mutation frequency in introduced genetic material.
• This phenomenon is a characteristic outcome of the transfection process itself, independent of vector replication.