An RNA polymerase II mutation in Drosophila melanogaster that mimics ultrabithorax

Mortin, Mark A.; Lefevre, George

doi:10.1007/bf00286108

Cited by 61 publications

(25 citation statements)

References 10 publications

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“…4E (15,16). These mutations map in "ultrabithorax-like" (ubi), a locus known to cause allele-specific variations in several other loci, some of which can affect fly morphogenesis (32). The allele specificity we have reported here with respect to amaR mutations and myogenesis in L6 myoblasts may be analogous to that observed in Drosophila spp.…”

Section: Myogenic Phenotypes Of Amar Mutants (I)supporting

confidence: 64%

Myogenic differentiation of L6 rat myoblasts: evidence for pleiotropic effects on myogenesis by RNA polymerase II mutations to alpha-amanitin resistance.

Crerar¹,

Leather²,

David³

et al. 1983

Mol. Cell. Biol.

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To assess the functional role of RNA polymerase II in the regulation of transcription during muscle differentiation, we isolated and characterized a large number of independent cx-amanitin-resistant (AmaR) mutants of L6 rat myoblasts that express both wild-type and altered RNA polymerase II activities. We also examined their myogenic (Myo) phenotype by determining their ability to develop into mature myotubes, to express elevated levels of muscle creatine kinase, and to synthesize muscle-characteristic proteins as detected by two-dimensional polyacrylamide gel electrophoresis. We found a two-to threefold increase in the frequency of clones with a myogenic-defective phenotype in the AmaR (RNA polymerase II) mutants as compared to control ethyl methane sulfonate-induced, 6-thioguanine-resistant (hypoxanthine, guanine phosphoribosyl transferase) mutants or to unselected survivors also exposed to ethyl methane sulfonate. Subsequent analysis showed that about half of these myogenic-defective AmaR mutants had a conditional Myo(ama) phenotype; when cultured in the presence of amanitin, they exhibited a Myo-phenotype; in its absence they exhibited a Myo+ phenotype. This conditional Myo(ama) phenotype is presumably caused by the inactivation by amanitin of the wild-type amanitin-sensitive RNA polymerase II activity and the subsequent rise in the level of mutant amanitin-resistant RNA polymerase II activity. In these Myo(ama) mutants, the wild-type RNA polymerase II is normally dominant with respect to the Myo+ phenotype, whereas the mutant RNA polymerase II is recessive and results in a Myo-phenotype only when the wild-type enzyme is inactivated. These findings suggest that certain mutations in the amaR structural gene for the amanitin-binding subunit of RNA polymerase II can selectively impair the transcription of genes specific for myogenic differentiation but not those specific for myoblast proliferation.The L6 rat myoblast cell line isolated by Yaffe (45) forms multinucleate myotubes and synthesizes elevated levels of several muscle-characteristic proteins when grown to confluence in physiological levels of calcium (10,19,30,31,(35)(36)(37)43

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Section: Myogenic Phenotypes Of Amar Mutants (I)supporting

confidence: 64%

Myogenic differentiation of L6 rat myoblasts: evidence for pleiotropic effects on myogenesis by RNA polymerase II mutations to alpha-amanitin resistance.

Crerar¹,

Leather²,

David³

et al. 1983

Mol. Cell. Biol.

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“…RNA polymerase II mutations can produce developmental defects in Drosophila melanogaster and in Caenorhabditis elegans (6,10,11,(23)(24)(25)30 (30). How these RNA polymerase II mutations cause developmental defects is not known.…”

Section: Resultsmentioning

confidence: 99%

RNA polymerase II mutants defective in transcription of a subset of genes.

1990

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Saccharomyces cerevisiae RNA polymerase II conditional mutants that selectively disrupt the synthesis of specific mRNAs were isolated. At the permissive temperature, several of the mutants were inositol auxotrophs as a result of inadequate induction of INO1 transcription. The transcriptional defects exhibited by one of these Ino-mutants (rpb2-2) were further investigated. The induction of GAL1O and HIS4 transcription in rpb2-2 strains was similar to that of wild-type strains, in contrast to the lack of induction of INOI transcription. When shifted to the nonpermissive temperature, cells containing rpb2-2 continued to accumulate some mRNAs but not others. Together, these results indicate that transcription of specific genes can be disrupted by RNA polymerase II mutations. The rpb2-2 allele alters an amino acid residue that occurs in a highly conserved segment of the RPB2 protein and that is shared by homologous subunits in other species.The regulation of eucaryotic gene expression occurs primarily at the level of selective transcription initiation by RNA polymerase II. Specific promoter sequences, transcriptional activating protein factors, and RNA polymerase all play a role in transcription initiation. Transcriptional activating proteins bind specifically to cis-acting promoter elements such as enhancer sequences or the TATA box (12, 21). The most thoroughly studied transcriptional activating proteins have separate domains for DNA-binding and transcriptional activation (reviewed in references 13 and 22). The mechanism(s) by which these proteins activate transcription initiation by RNA polymerase II is unclear.RNA polymerase II is composed of 9 to 14 polypeptides of 10 to 220 kilodaltons that are substantially conserved in size and structure throughout eucaryotes (31). The yeast nuclear RNA polymerases are among the best studied of the eucaryotic polymerases. Yeast RNA polymerase II contains 10 polypeptides, 7 of which are unique to the enzyme and 3 of which are shared with the other two polymerases. Genes encoding seven of the yeast RNA polymerase II subunits have been isolated and characterized (17,18,29,(35)(36)(37); N. A. Woychik, S.-M. Liao, P. Kolodziej, and R. A. Young, Genes Dev., in press). The sequences of the two largest subunits, RPBJ and RPB2 (1,35), reveal that the RPB1 and RPB2 proteins are similar to the Escherichia coli RNA polymerase subunits P' (RpoC) and 1 (RpoB), respectively.Biochemical and genetic evidence indicates that the RNA polymerase ,B subunit interacts with the a subunit, which is essential for selective transcription initiation in E. coli (9,26,32,38). It is not clear how components of the eucaryotic RNA polymerase interact with transcription factors.To obtain clues to the functions of the RPBI and RPB2 subunits, we have isolated and investigated RNA polymerase mutants that affect mRNA synthesis. We previously described a temperature-sensitive RPBJ mutant that rapidly ceases all mRNA synthesis upon transfer to the nonpermis-

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“…In Drosophila melanogaster, Matthews and Kaufman (37) identified a lethal mutation that produced an electrophoretic variant of the 84B ax-tubulin and that failed to complement B2t alleles for male fertility. Stearns (42).…”

Section: Discussionmentioning

confidence: 99%

Interacting proteins identified by genetic interactions: a missense mutation in alpha-tubulin fails to complement alleles of the testis-specific beta-tubulin gene of Drosophila melanogaster.

Hays¹,

Deuring²,

Robertson³

et al. 1989

Mol. Cell. Biol.

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In this paper we demonstrate that failure to complement between mutations at separate loci can be used to identify genes that encode interacting structural proteins. A mutation (nc33) identified because it failed to complement mutant alleles of the gene encoding the testis-specific 02-tubulin of Drosophila melanogaster (B2t) did not map to the B2t locus. We show that this second-site noncomplementing mutation is a missense mutation in ac-tubulin that results in substitution of methionine in place of valine at amino acid 177. Because a-and

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An RNA polymerase II mutation in Drosophila melanogaster that mimics ultrabithorax

Cited by 61 publications

References 10 publications

Myogenic differentiation of L6 rat myoblasts: evidence for pleiotropic effects on myogenesis by RNA polymerase II mutations to alpha-amanitin resistance.

Myogenic differentiation of L6 rat myoblasts: evidence for pleiotropic effects on myogenesis by RNA polymerase II mutations to alpha-amanitin resistance.

RNA polymerase II mutants defective in transcription of a subset of genes.

Interacting proteins identified by genetic interactions: a missense mutation in alpha-tubulin fails to complement alleles of the testis-specific beta-tubulin gene of Drosophila melanogaster.

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