Nowa1p and Nowa2p: Novel Putative RNA Binding Proteins Involved in trans-Nuclear Crosstalk in Paramecium tetraurelia

Nowacki, Mariusz; Zagórski-Ostoja, Włodzimierz; Meyer, Éric

doi:10.1016/j.cub.2005.07.033

Cited by 75 publications

(104 citation statements)

References 39 publications

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“…They might be required for the formation of a chromatin environment that is a prerequisite for proper arrangement of Pdd1p and Jub6p on heterochromatinized IESs, although we do not exclude the possibility that they play direct roles in the aggregation process of heterochromatin body assembly. Two proteins, Nowa1p and Nowa2p, which are required for small-RNA-dependent IES elimination in the other ciliate Paramecium tetraurelia, are similar to the RNA-binding prion protein Prp27 (Gabus et al, 2001;Nowacki et al, 2005). Therefore, although Jub6p and Nowa1p and Nowa2p share no obvious homology at their amino-acid sequence level, prion-like proteins could play essential roles in one or more processes of DNA elimination in ciliates.…”

Section: Discussionmentioning

confidence: 99%

Heterochromatin aggregation during DNA elimination in Tetrahymena is facilitated by a prion-like protein

Kataoka

Mochizuki

2017

Journal of Cell Science

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Regulated aggregations of prion and prion-like proteins play physiological roles in various biological processes. However, their structural roles in the nucleus are poorly understood. Here, we show that the prion-like protein Jub6p is involved in the regulation of chromatin structure in the ciliated protozoan Tetrahymena thermophila. Jub6p forms sodium dodecyl sulfate (SDS)-resistant aggregates when it is ectopically expressed in vegetative cells and binds to RNA in vitro. Jub6p is a heterochromatin component and is important for the formation of heterochromatin bodies during the process of programmed DNA elimination. We suggest that RNAprotein aggregates formed by Jub6p are an essential architectural component for the assembly of heterochromatin bodies.

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Section: Discussionmentioning

confidence: 99%

Heterochromatin aggregation during DNA elimination in Tetrahymena is facilitated by a prion-like protein

Kataoka

Mochizuki

2017

Journal of Cell Science

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“…Thus the period in which this regulation is enforced overlaps with the formation of the conjusome and the apparent shuttling of Pdd1p from the parental macronucleus to this structure prior to its anlagen localization, which leads us to speculate that this genome comparison may be through the action of homologous RNAs in these cytoplasmic bodies. The putative Paramecium RNA binding protein, NOWA1p, is required for the elimination of IESs that exhibit similar epigenetic regulation by the content of the parental macronucleus and has been demonstrated to relocate between the maternal macronucleus and the anlagen (Nowacki et al, 2005). It is not known whether a conjusome-like structure exists in Paramecium, but the regulation of DNA rearrangement by the parental somatic genome appears to be a conserved feature of this process in ciliates.…”

Section: Discussionmentioning

confidence: 99%

Identification of novel chromatin-associated proteins involved in programmed genome rearrangements inTetrahymena

Meng

Yao

Halasz

et al. 2007

Journal of Cell Science

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Extensive DNA rearrangements occur during the differentiation of the developing somatic macronuclear genome from the germ line micronuclear genome of Tetrahymena thermophila. To identify genes encoding proteins likely to be involved in this process, we devised a cytological screen to find proteins that specifically localize in macronuclear anlagen (Lia proteins) at the stage when rearrangements occur. We compared the localization of these with that of the chromodomain protein, Pdd1p, which is the most abundant known participant in this genome reorganization. We show that in live cells, Pdd1p exhibits dynamic localization, apparently shuttling from the parental to the developing nuclei through cytoplasmic bodies called conjusomes. Visualization of GFP-tagged Pdd1p also highlights the substantial three-dimensional nuclear reorganization in the formation of nuclear foci that occur coincident with DNA rearrangements. We found that late in macronuclear differentiation, four of the newly identified proteins are organized into nuclear foci that also contain Pdd1p. These Lia proteins are encoded by primarily novel genes expressed at the beginning of macronuclear differentiation and have properties or recognizable domains that implicate them in chromatin or nucleic acid binding. Three of the Lia proteins also localize to conjusomes, a result that further implicates this structure in the regulation of DNA rearrangement.

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“…RNAi has also been implicated in the programmed excision of excess DNA in ciliated protozoa such as T. thermophila and P. tetraurelia (Garnier et al 2004;Mochizuki and Gorovsky 2005;Nowacki et al 2005;Yao and Chao 2005). This process requires small RNAs, termed scan RNAs, and components of the RNA machinery that direct H3K9 methylation of the chromatin associated with the sequences to be deleted (Garnier et al 2004;Liu et al 2004b;Mochizuki and Gorovsky 2005;Yao and Chao 2005).…”

Section: Additional (Derived?) Functions Of the Rnai Machinerymentioning

confidence: 99%

On the origin and functions of RNA-mediated silencing: from protists to man

2006

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Double-stranded RNA has been shown to induce gene silencing in diverse eukaryotes and by a variety of pathways. We have examined the taxonomic distribution and the phylogenetic relationship of key components of the RNA interference (RNAi) machinery in members of five eukaryotic supergroups. On the basis of the parsimony principle, our analyses suggest that a relatively complex RNAi machinery was already present in the last common ancestor of eukaryotes and consisted, at a minimum, of one Argonautelike polypeptide, one Piwi-like protein, one Dicer, and one RNAdependent RNA polymerase. As proposed before, the ancestral (but non-essential) role of these components may have been in defense responses against genomic parasites such as transposable elements and viruses. From a mechanistic perspective, the RNAi machinery in the eukaryotic ancestor may have been capable of both small-RNA-guided transcript degradation as well as transcriptional repression, most likely through histone modifications. Both roles appear to be widespread among living eukaryotes and this diversification of function could account for the evolutionary conservation of duplicated Argonaute-Piwi proteins. In contrast, additional RNAi-mediated pathways such as RNA-directed DNA methylation, programmed genome rearrangements, meiotic silencing by unpaired DNA, and miRNA-mediated gene regulation may have evolved independently in specific lineages.

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Nowa1p and Nowa2p: Novel Putative RNA Binding Proteins Involved in trans-Nuclear Crosstalk in Paramecium tetraurelia

Cited by 75 publications

References 39 publications

Heterochromatin aggregation during DNA elimination in Tetrahymena is facilitated by a prion-like protein

Heterochromatin aggregation during DNA elimination in Tetrahymena is facilitated by a prion-like protein

Identification of novel chromatin-associated proteins involved in programmed genome rearrangements inTetrahymena

On the origin and functions of RNA-mediated silencing: from protists to man

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