Isolation of a full-length mouse cDNA clone coding for an immunologically distinct p53 molecule

Area of Science:

• Molecular Biology
• Cancer Research
• Virology

Background:

• The p53 tumor suppressor gene plays a critical role in cellular regulation.
• Abelson murine leukemia virus-transformed cell lines, like L12, often lack functional p53.
• Restoring p53 expression is a key strategy in cancer research.

Purpose of the Study:

• To investigate the characteristics of p53 protein expressed after gene transfection.
• To compare p53 protein derived from genomic DNA versus cDNA.
• To analyze the antigenic properties and molecular features of reconstituted p53.

Main Methods:

• Transfection of L12 cells with genomic p53 and p53 cDNA (pM8).
• Immunoprecipitation using a panel of monoclonal and polyclonal anti-p53 antibodies.
• Analysis of protein molecular size and peptide mapping.

Main Results:

• Genomic p53 transfection reconstituted p53 expression with native antigenic determinants.
• p53 cDNA transfection resulted in a protein with altered antigenic properties, lacking binding to specific monoclonal antibodies (PAb122, PAb421).
• Both genomic and cDNA derived p53 proteins showed identical molecular sizes and peptide maps.

Conclusions:

• Genomic p53 transfection likely induces diverse mRNA species, leading to a complete p53 protein.
• Cloned p53 cDNA (pM8) represents a single mRNA species, producing a distinct p53 protein variant.
• Differences in p53 protein immunogenicity arise from the source of the transfected genetic material.