Complete transformation by adenovirus 2 requires both E1A proteins.

Area of Science:

• Molecular Biology
• Virology
• Cell Biology

Background:

• Adenovirus type 2 (Ad2) transforms rodent cells using proteins encoded by the early region 1A (E1A).
• Two highly related E1A proteins, 289 and 243 amino acids long, are expressed in Ad2-transformed cells.

Purpose of the Study:

• To investigate the distinct roles of the 289 and 243 amino acid E1A proteins in adenovirus-mediated cell transformation.
• To determine the requirement of each E1A protein for anchorage-independent growth and viral replication.

Main Methods:

• Utilized adenovirus mutants expressing either the 289 or 243 amino acid E1A protein.
• Assessed the transformed phenotype, including anchorage-independent growth.
• Evaluated viral replication efficiency in standard and growth-arrested human cells.

Main Results:

• Both E1A proteins are necessary for the fully transformed phenotype; each alone induces a partial transformation.
• The 243 amino acid E1A protein is crucial for anchorage-independent growth.
• Transformation mediated by the 243 amino acid E1A protein alone is cold-sensitive.
• Efficient viral replication in growth-arrested human cells requires both E1A proteins, whereas only the 289 amino acid protein suffices for replication in standard cell culture.

Conclusions:

• The 289 and 243 amino acid E1A proteins collaborate to achieve complete adenovirus-induced cell transformation.
• The 243 amino acid E1A protein plays a critical role in anchorage-independent growth and efficient viral replication in specific cellular contexts.