The protein encoded by the adenovirus E1A gene has several biological activities including the stimulation of transcription of some genes, the repression of transcription of other genes, and cell immortalization and transformation. This proposal will examine two aspects of the E1A. First, it is now generally accepted that nuclear proteins, of which E1A is an example, contain within their primary sequences discrete regions that target them to the nucleus. E1A is unusual in that it contains two nuclear targeting domains that are differentially used during development. The fine structure of these domains will be assessed as well as the exact time during development when each is used. The experiments will be performed in the convenient model system, oocytes and embryos of the frog Xenopus laevis. E1A mutants will be constructed such that certain amino acid residues are deleted from the protein. In addition, chimeric proteins will be constructed that fuse certain regions of E1A to B-galactosidase. All constructions will be performed at the DNA level, and the resulting mutant proteins will be expressed either in vitro or in vivo. The second aspect of E1A to be examined is its rate of turnover. E1A normally has a very short half-life within cells. This proposal will extend preliminary observations that E1A turnover is related to mRNA translation and that the amino terminal region of E1A is indispensible for instability. This proposal will assess the connection between E1A translation and instability. These experiments will also make use of deletion and chimeric E1A mutants similar to those described above. Protein turnover will be assayed in injected Xenopus oocytes and transfected somatic cells. E1A greatly influences growth control of cells. Therefore, a deciphering of the mechanism by which it enters the nucleus, where it exerts its effects, and the length of time it remains active within cells are of crucial importance for our understanding of cancer.

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National Cancer Institute (NCI)
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Molecular Cytology Study Section (CTY)
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Worcester Foundation for Biomedical Research
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Wu, L; Good, P J; Richter, J D (1997) The 36-kilodalton embryonic-type cytoplasmic polyadenylation element-binding protein in Xenopus laevis is ElrA, a member of the ELAV family of RNA-binding proteins. Mol Cell Biol 17:6402-9
Villarreal, X C; Richter, J D (1995) Analysis of ATF2 gene expression during early Xenopus laevis development. Gene 153:225-9
Gebauer, F; Xu, W; Cooper, G M et al. (1994) Translational control by cytoplasmic polyadenylation of c-mos mRNA is necessary for oocyte maturation in the mouse. EMBO J 13:5712-20
Standiford, D M; Richter, J D (1992) Analysis of a developmentally regulated nuclear localization signal in Xenopus. J Cell Biol 118:991-1002
Paris, J; Swenson, K; Piwnica-Worms, H et al. (1991) Maturation-specific polyadenylation: in vitro activation by p34cdc2 and phosphorylation of a 58-kD CPE-binding protein. Genes Dev 5:1697-708
Simon, R; Richter, J D (1990) The degradation sequence of adenovirus E1A consists of the amino-terminal tetrapeptide Met-Arg-His-Ile. Mol Cell Biol 10:5609-15
Slavicek, J M; Jones, N C; Richter, J D (1989) A karyophilic signal sequence in adenovirus type 5 E1A is functional in Xenopus oocytes but not in somatic cells. J Virol 63:4047-50
McGrew, L L; Dworkin-Rastl, E; Dworkin, M B et al. (1989) Poly(A) elongation during Xenopus oocyte maturation is required for translational recruitment and is mediated by a short sequence element. Genes Dev 3:803-15
Richter, J D (1989) In vivo photocrosslinking reveals that transcription factor binding to the mammalian ATF recognition sequence is required for E1A-induced transactivation in injected Xenopus laevis oocytes. Nucleic Acids Res 17:4503-16
McGrew, L L; Richter, J D (1989) Xenopus oocyte poly(A) RNAs that hybridize to a cloned interspersed repeat sequence are not translatable. Dev Biol 134:267-70

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