Sequence organization of the Balbiani ring 2.1 gene in Chironomus tentans.

Wieslander, Lars; Paulsson, Gabrielle

doi:10.1073/pnas.89.10.4578

Cited by 22 publications

(6 citation statements)

References 47 publications

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“…Two approaches have given us a detailed view of message export. The giant particle containing the 75S RNA encoded by the Balbiani rings of C. tentans seems to dock on to the tip of the basket, before unfolding and passing through the centre of the basket on its way to the cytoplasm (Wieslander and Paulsson 1992;Wieslander 1994;Daneholt 1997). Gold particles coated with RNA have also been microinjected into the nuclei of Xenopus oocytes; after cutting thick sections, they also seem to pass down the central axis (Feldherr et al 1984;Dworetzky and Feldherr 1988;Richardson et al 1988;Pante et al 1997).…”

Section: Through the Porementioning

confidence: 94%

The path that RNA takes from the nucleus to the cytoplasm: a trip with some surprises

Iborra

2002

Histochem Cell Biol

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Section: Through the Porementioning

confidence: 94%

The path that RNA takes from the nucleus to the cytoplasm: a trip with some surprises

Iborra

2002

Histochem Cell Biol

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“…The exon-intron structure of the BR genes is known (Wieslander and Paulsson, 1992;Figure 2A), and the morphology of the active BR genes and BR mRNPs has been characterized in detail (Skoglund et al, 1983). The active BR genes are loaded with multiple RNA polymerases and, at any given time, each BR gene is being transcribed simultaneously by many RNA polymerases that have reached different elongation stages.…”

Section: Ct-rrp4 Is Present Along the Entire Br Transcription Unitmentioning

confidence: 99%

The Exosome Associates Cotranscriptionally with the Nascent Pre-mRNP through Interactions with Heterogeneous Nuclear Ribonucleoproteins

Hessle¹,

Björk²,

Sokolowski³

et al. 2009

MBoC

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Eukaryotic cells have evolved quality control mechanisms to degrade aberrant mRNA molecules and prevent the synthesis of defective proteins that could be deleterious for the cell. The exosome, a protein complex with ribonuclease activity, is a key player in quality control. An early quality checkpoint takes place cotranscriptionally but little is known about the molecular mechanisms by which the exosome is recruited to the transcribed genes. Here we study the core exosome subunit Rrp4 in two insect model systems, Chironomus and Drosophila. We show that a significant fraction of Rrp4 is associated with the nascent pre-mRNPs and that a specific mRNA-binding protein, Hrp59/hnRNP M, interacts in vivo with multiple exosome subunits. Depletion of Hrp59 by RNA interference reduces the levels of Rrp4 at transcription sites, which suggests that Hrp59 is needed for the exosome to stably interact with nascent pre-mRNPs. Our results lead to a revised mechanistic model for cotranscriptional quality control in which the exosome is constantly recruited to newly synthesized RNAs through direct interactions with specific hnRNP proteins. INTRODUCTIONExpression of protein-coding genes is a complex multistep process. Precursor messenger RNAs (pre-mRNAs) are synthesized by RNA polymerase II (Pol-II) and assembled into ribonucleoprotein (RNP) complexes during transcription. The pre-mRNPs must be processed to become mature mRNPs, which are exported to the cytoplasm and translated into protein. Mutations in the DNA or errors in the transcription and processing reactions can lead to the synthesis of aberrant mRNPs. Eukaryotic cells have evolved quality control mechanisms that identify aberrant mRNPs and prevent their expression into protein. In the yeast Saccharomyces cerevisiae there are at least three nuclear steps of mRNP biogenesis that are under surveillance: the cleavage and polyadenylation of the 3Ј end (Hilleren et al., 2001), the assembly of the mRNA-protein complexes (Zenklusen et al., 2002;Luna et al., 2005), and the removal of introns (Galy et al., 2004). In all cases, mRNPs with assembly and/or processing defects are detected by nuclear surveillance mechanisms, retained in the nucleus, and degraded (reviewed by Vinciguerra and Stutz, 2004;Sommer and Nehrbass, 2005;Saguez et al., 2005). Genetic studies in S. cerevisiae have identified the nuclear exosome as a key player in the recognition and retention of defective transcripts (reviewed by Jensen et al., 2003;Houseley et al., 2006;Vanacova and Stefl, 2007;Schmid and Jensen, 2008).The exosome is a protein complex with ribonuclease activity (Mitchell et al., 1997;Allmang et al., 1999;Mitchell and Tollervey, 2000). The core of the exosome has a barrel-like architecture (reviewed by Lorentzen et al., 2008). The barrel is made of nine protein subunits organized into two rings, a hexameric ring and a trimeric ring, and the structure of the barrel is conserved throughout evolution (Lorentzen et al., 2005;Liu et al., 2006;Wang et al., 2007). Two additional proteins, Dis3/Rrp44 and R...

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“…The BR1 and BR2 genes, 35-40 kb in size, belong to the same gene family and exhibit a similar exon-intron organization with five exons and four introns (for review, see Wieslander 1994). A remarkable feature of the BR transcripts is that one of the exons (number 4) is exceptionally long (>30 kb), whereas the introns and the other exons are relatively small (<1.5 kb) and located close to the 5' or 3' ends (Wieslander and Paulsson 1992). The three introns close to the 5' end seem to be spliced before one-third of the transcript is synthesized, whereas the fourth intron close to the 3' end is usually spliced post-transcriptionally (Baur4n and Wieslander 1994).…”

mentioning

confidence: 99%

A protein of the SR family of splicing factors binds extensively to exonic Balbiani ring pre-mRNA and accompanies the RNA from the gene to the nuclear pore.

Alzhanova-Ericsson¹,

Sun²,

Visa³

et al. 1996

Genes Dev.

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We report on the molecular cloning and intracellular localization of a heterogeneous nuclear ribonucleoprotein (hnRNP), Ct-hrp45, one of the major components of pre-mRNP particles in Chironomus tentans. It is shown that hrp45 belongs to the SR family of splicing factors and exhibits high sequence similarity to Drosophila SRp55/B52 and human SF2/ASF. The distribution of hrp45 within the C. tentans salivary gland cells is studied by immunocytology. The hrp45 protein is found to be abundant in the nucleus, whereas it is undetectable in the cytoplasm. The fate of hrp45 in specific pre-mRNP particles, the Balbiani ring (BR) granules, is revealed by immunoelectron microscopy. It is observed that hrp45 is associated with the growing BR pre-mRNP particles and is being added continuously concomitant with the growth of the transcript, indicating that hrp45 is bound extensively to exon 4, which comprises 80-90% of the primary transcript. Furthermore, hrp45 remains bound to the BR RNP particles in the nucleoplasm and is not released until the particles translocate through the nuclear pore. Thus, hrp45 behaves as an hnRNP protein linked to exon RNA (and perhaps also to the introns) rather than as a spliceosome component connected to the assembly and disassembly of spliceosomes. It seems that hrp45, and possibly also other SR family proteins, is playing an important role in the structural organization of pre-mRNP particles and is perhaps participating not only in splicing but also in other intranuclear events.

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Sequence organization of the Balbiani ring 2.1 gene in Chironomus tentans.

Abstract: Balbiani rings are giant chromosomal puffs, containing related genes that provide unique possibilities for in vivo analysis of gene expression at the chromatin and ribonucleoprotein levels. Here, the 5' end of the Balbiani ring 2

Cited by 22 publications

References 47 publications

The path that RNA takes from the nucleus to the cytoplasm: a trip with some surprises

The path that RNA takes from the nucleus to the cytoplasm: a trip with some surprises

The Exosome Associates Cotranscriptionally with the Nascent Pre-mRNP through Interactions with Heterogeneous Nuclear Ribonucleoproteins

A protein of the SR family of splicing factors binds extensively to exonic Balbiani ring pre-mRNA and accompanies the RNA from the gene to the nuclear pore.

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