Showing papers by "Arnold J. Levine published in 1981"

Post-translational regulation of the 54K cellular tumor antigen in normal and transformed cells.

Abstract: The 54K cellular tumor antigen has been translated in vitro, using messenger ribonucleic acids from simian virus 40 (SV40)-transformed cells or 3T3 cells. The in vitro 54K product could be immunoprecipitated with SV40 tumor serum and had a peptide map that was similar, but not identical, to the in vivo product. The levels of this 54K protein in SV3T3 cells were significantly higher than those detected in 3T3 cells (D. I. H. Linzer, W. Maltzman, and A. J. Levine, Virology 98:308-318, 1979). In spite of this, the levels of translatable 54K messenger ribonucleic acid from 3T3 and SV3T3 cells were roughly equivalent or often greater in 3T3 cells. Pulse-chase experiments with the 54K protein from 3T3 or SV3T3 cells demonstrated that this protein, once synthesized, was rapidly degraded in 3T3 cells but was extremely stable in SV3T3 cells. Similarly, in an SV40 tsA-transformed cell line, temperature sensitive for the SV40 T-antigen, the 54K protein was rapidly turned over at the nonpermissive temperature and stable at the permissive temperature, whereas the levels of translatable 54K messenger ribonucleic acid at each temperature were roughly equal. These results demonstrate a post-translational regulation of the 54K cellular tumor antigen and suggest that this control is mediated by the SV40 large T-antigen.

Isolation and characterization of polyoma host range mutants that replicate in nullipotential embryonal carcinoma cells.

Abstract: Polyoma wild-type virus replicates in most murine differentiated cells but fails to produce virus in murine embryonal carcinoma cells. Polyoma host range mutants have been isolated that replicate in several nullipotential embryonal carcinoma cell lines but fail to replicate in a pluripotential cell line. The final virus yield of these host range mutants is dependent upon the multiplicity of infection in both differentiated cells and nullipotent embryonal carcinoma cells. Two independently derived host range mutants contain the same single base pair change (A.T to G.C) and a 33- and 67-base pair duplication of those viral DNA sequences containing this point mutation. This duplication of viral DNA is located at 69 map units on the polyoma genome on the late gene side of the origin of viral DNA replication (70.5 map units). This type of mutation suggests several models to explain the polyoma host range restriction in embryonal carcinoma cells.

Viruses as Probes for Development and Differentiation

Abstract: Publisher Summary This chapter presents study of viruses that has contributed in two important ways to a better understanding of gene regulation and developmental biology. First, an analysis of the processes of viral replication itself has provided new principles of gene organization, DNA, RNA, and protein synthesis, modification, and processing. Second, the use of viruses and the regulation of their gene expression to probe the biochemical and genetic alterations of a developmentally interesting host cell has begun to provide useful insights into gene regulation of differentiated cells. Information from both of these approaches has come together to provide a more complete picture of developmental processes. A good example of this can be illustrated with recent studies of RNA processing. The capping of the 5´ ends of eukaryotic RNAs and its utility in protein synthesis observed with reoviruse. Viruses have also been useful in defining and recognizing cellular genes and even their gene products. Just as viruses have been useful in identifying cellular genes and their products, the differentiated host cell has been essential in the identification of viral genes, their products, and their phenotypes.

Teratocarcinoma transplantation rejection loci: genetic localization of the Gt-1 locus on chromosome 17 and the expression of alternate alleles.

Abstract: A series of congenic mice on the BALB/c genetic background have been employed to localize a teratocarcinoma transplantation rejection locus, Gt-1, to the K side of the H-2 locus on chromosome 17. Previous studies have placed the Gt-1 sv allele about 8 centimorgans away from the H-2 b or H-2 bv1 locus. Teratocarcinomas derived from 129/sv mice, Gt-1 sv (H-2K bv1/H-2D bv1), are rejected by BALB/c (H-2K d/H-2Dd) and BALB-G mice (H-2K d/H2D-b, but form tumors in BALB-B (H-2K b/H2D b) and BALB/5R5 mice (H-2K b/H2D d). In the reciprocal tumor-rejection test, a BALB/c teratocarcinoma was rejected by immunized BALB·B mice, but formed tumors in the immunized isogenic BALB/c mouse. These studies demonstrate the reciprocal expression of two Gt-1 alleles, one Gt-1 c, in BALB/c mice, and the other, Gt-1 sv, in the congenic BALB·B mice. Shedlovsky and co-workers have placed the Gt-1 locus in a similar location on the K side of the H-2 locus on chromosome 17.

Papovaviruses as Probes to Study Developmental Changes in Embryonal Carcinoma Cells

Abstract: Polyoma virus undergoes a productive infection, and SV40 expresses it’s early gene products in most differentiated mouse cells On the other hand, neither virus is able to produce detectable levels of their early proteins in murine embryonal carcinoma cells (EC cells), which are the stem cells of teratocarcinomas (Swartzendruber and Lehman 1975; Boccara and Kelly 1978) If pluripotent EC cells are allowed to differentiate, these cells can then produce infectious polyoma virus or be transformed by SV40 and express early viral proteins (Topp et al 1977; Maltzman et al 1979) The block to polyoma or SV40 gene expression in murine EC cells has been investigated (Segal et al 1979; Swartzendruber et al 1977) Nullipotential F9 cells infected with SV40 have low levels of viral transcriptional intermediates and SV40 RNA The viral RNA synthesized in F9 cells is not spliced into functional mRNA’s and thus early viral proteins are not expressed (Segal et al 1979) Polyoma infection of pluripoent PCC-4-aza-1 EC cells results in extremly low levels of viral RNA compared to an infection of differentiated mouse cells (Katinka et al 1980) Polyoma host range mutants have been isolated which produce infectious virus in PCC-4-aza-1 EC cells (Vasseur et al 1980), but fail to replicate in F9 EC cells These data indicate that the block to papovavirus gene expression in EC cells may differ in two distinct EC cell lines (F9 and PCC-4-aza-1) and the expression of these early viral genes may be regulated by developmental changes in the cell type As such, the papovaviruses appear to be excellent tools to probe the molecular basis of developmental regulation