Mouse adenovirus type 1 early region 1A is dispensable for growth in cultured fibroblasts.
Mouse adenovirus type 1 (MAV-1) mutants with deletions of conserved regions of early region 1A (E1A) or with point mutations that eliminate translation of E1A were used to determine the role of E1A in MAV-1 replication. MAV-1 E1A mutants expressing no E1A protein grew to titers comparable to wild-type MAV-1 titers on mouse fibroblasts (3T6 fibroblasts and fibroblasts derived from Rb+/+, Rb+/-, and Rb-/- transgenic embryos). To test the hypothesis that E1A could induce a quiescent cell to reenter the cell cycle, fibroblasts were serum starved to stop DNA replication and cellular replication and then infected with the E1A mutant and wild-type viruses. All grew to equivalent titers. Steady-state levels of MAV-1 early mRNAs (E1A, E1B, E2, E3, and E4) from 3T6 cells infected with wild-type or E1A mutant virus were examined by Northern analysis. Steady-state levels of mRNAs from the mutant-infected cells were comparable to or greater than the levels found in wild-type virus infections for most of the early regions and for two late genes. The E2 mRNA levels were slightly reduced in all mutant infections relative to wild-type infections. E1A mRNA was not detected from infections with the MAV-1 E1A null mutant, pmE109, or from infections with similar MAV-1 E1A null mutants, pmE112 and pmE113. The implications for the lack of a requirement of E1A in cell culture are discussed.
Ying
B
B
Department of Genetics, University of Georgia, Athens, Georgia 30602, USA.
Smith
K
K
Spindler
K R
KR
D017500:Adenovirus E1A Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D017501:Adenovirus E1B Proteins / Q000235:genetics; D017502:Adenovirus E2 Proteins / Q000235:genetics; D017503:Adenovirus E3 Proteins / Q000235:genetics; D000818:Animals; D002460:Cell Line; D017921:Mastadenovirus / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D051379:Mice; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D016160:Retinoblastoma Protein / Q000235:genetics / Q000378:metabolism; D012710:Serum Albumin, Bovine; D013997:Time Factors; D015533:Transcriptional Activation; D014779:Virus Replication
D017500:Adenovirus E1A Proteins; D017501:Adenovirus E1B Proteins; D017502:Adenovirus E2 Proteins; D017503:Adenovirus E3 Proteins; D016160:Retinoblastoma Protein; D012710:Serum Albumin, Bovine