Sm proteins, the constituents of the spliceosome, are components of nuage and mitochondrial cement in Xenopus oocytes

Biliński, S; Jaglarz, Mariusz K.; Szymańska, Beata; Etkin, Laurence D.; Kloc, Małgorzata

doi:10.1016/j.yexcr.2004.05.016

Cited by 50 publications

(49 citation statements)

References 41 publications

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“…Here, it was determined that two Drosophila Sm proteins can specifically accumulate in the pole plasm during the final stage of oocyte differentiation until the formation of pole cells in blastoderm stage embryos. Inclusion of Sm proteins in cytoplasmic structures is a rather novel finding, although they have been detected outside of the nucleus in the germ cells of various species, including Caenorhabditis elegans (Barbee et al, 2002), Xenopus laevis (Bilinski et al, 2004), rat (Moussa et al, 1994;Toyooka et al, 2000) and mouse (Chuma et al, 2003). The present data show that access of SmB and SmD3 to the pole plasm depends on sDMA methylation.…”

Section: Discussion Arginine Methylation-dependent Localisation Of Smsupporting

confidence: 50%

Arginine methylation of SmB is required for Drosophila germ cell development

Anne

2010

Development

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SUMMARYSm proteins constitute the common core of spliceosomal small nuclear ribonucleoproteins. Although Sm proteins are known to be methylated at specific arginine residues within the C-terminal arginine-glycine dipeptide (RG) repeats, the biological relevance of these modifications remains unknown. In this study, a tissue-specific function of arginine methylation of the SmB protein was identified in Drosophila. Analysis of the distribution of SmB during oogenesis revealed that this protein accumulates at the posterior pole of the oocyte, a cytoplasmic region containing the polar granules, which are necessary for the formation of primordial germ cells. The pole plasm localisation of SmB requires the methylation of arginine residues in its RG repeats by the Capsuléen-Valois methylosome complex. Functional studies showed that the methylation of these arginine residues is essential for distinct processes of the germline life cycle, including germ cell formation, migration and differentiation. In particular, the methylation of a subset of these arginine residues appears essential for the anchoring of the polar granules at the posterior cortex of the oocyte, whereas the methylation of another subset controls germ cell migration during embryogenesis. These results demonstrate a crucial role of arginine methylation in directing the subcellular localisation of SmB and that this modification contributes specifically to the establishment and development of germ cells.

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Section: Discussion Arginine Methylation-dependent Localisation Of Smsupporting

confidence: 50%

Arginine methylation of SmB is required for Drosophila germ cell development

Anne

2010

Development

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“…Sm components of the splicesome have been shown to localize to germ plasm in multiple species, and previous RNAi depletion of the C. elegans Sm proteins disrupted P-granule patterns in embryos (Moussa et al 1994;Barbee et al 2002;Chuma et al 2003;Bilinski et al 2004;Barbee and Evans 2006). However, previous RNAi depletion of other splicing components did not disrupt P-granule patterns in embryos (Barbee et al 2002), suggesting that P-granule integrity and perinuclear localization in embryonic cells do not depend on pre-mRNA splicing.…”

Section: Resultsmentioning

confidence: 94%

“…Nascent transcripts are processed in the nucleus by spliceosomes prior to their export as mature mRNAs. Sm proteins are core components of nuclear spliceosomes and are also concentrated in the cytoplasmic germ granules of multiple species (Moussa et al 1994;Chuma et al 2003;Barbee et al 2002;Bilinski et al 2004). In C. elegans, Sm proteins are required for proper P-granule localization to the nuclear periphery; it has been proposed that this role is independent of premRNA splicing (Barbee and Evans 2006).…”

Section: Discussionmentioning

confidence: 99%

A Genomewide RNAi Screen for Genes That Affect the Stability, Distribution and Function of P Granules in Caenorhabditis elegans

2009

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P granules are non-membrane-bound organelles found in the germ-line cytoplasm throughout Caenorhabditis elegans development. Like their ''germ granule'' counterparts in other animals, P granules are thought to act as determinants of the identity and special properties of germ cells, properties that include the unique ability to give rise to all tissues of future generations of an organism. Therefore, understanding how P granules work is critical to understanding how cellular immortality and totipotency are retained, gained, and lost. Here we report on a genomewide RNAi screen in C. elegans, which identified 173 genes that affect the stability, localization, and function of P granules. Many of these genes fall into specific classes with shared P-granule phenotypes, allowing us to better understand how cellular processes such as protein degradation, translation, splicing, nuclear transport, and mRNA homeostasis converge on P-granule assembly and function. One of the more striking phenotypes is caused by the depletion of CSR-1, an Argonaute associated with an endogenous siRNA pathway that functions in the germ line. We show that CSR-1 and two other endo-siRNA pathway members, the RNA-dependent RNA polymerase EGO-1 and the helicase DRH-3, act to antagonize RNA and P-granule accumulation in the germ line. Our findings strengthen the emerging view that germ granules are involved in numerous aspects of RNA metabolism, including an endo-siRNA pathway in germ cells.

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“…Importantly, Sm proteins, but not core splicing factors, are present within P-granules (Barbee et al, 2002). In addition, Sm proteins have been shown to localize to the mitochondrial cement in Xenopus oocytes and to the chromatoid body in mouse spermatocytes, structures that are equivalent to those present within the fruit fly pole plasm (Bilinski et al, 2004;Chuma et al, 2003). Finally, Drosophila mutants in dart5 (capsuleen), an arginine methyltransferase responsible for post-translational modification of Sm proteins, are unable to specify germ cells (Anne et al, 2007;Gonsalvez et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Sm proteins specify germ cell fate by facilitatingoskarmRNA localization

et al. 2010

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SUMMARYSm and Sm-like proteins are RNA-binding factors found in all three domains of life. Eukaryotic Sm proteins play essential roles in pre-mRNA splicing, forming the cores of spliceosomal small nuclear ribonucleoproteins (snRNPs). Recently, Sm proteins have been implicated in the specification of germ cells. However, a mechanistic understanding of their involvement in germline specification is lacking and a germline-specific RNA target has not been identified. We demonstrate that Drosophila SmB and SmD3 are specific components of the oskar messenger ribonucleoprotein (mRNP), proper localization of which is required for establishing germline fate and embryonic patterning. Importantly, oskar mRNA is delocalized in females harboring a hypomorphic mutation in SmD3, and embryos from mutant mothers are defective in germline specification. We conclude that Sm proteins function to establish the germline in Drosophila, at least in part by mediating oskar mRNA localization.

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Sm proteins, the constituents of the spliceosome, are components of nuage and mitochondrial cement in Xenopus oocytes

Cited by 50 publications

References 41 publications

Arginine methylation of SmB is required for Drosophila germ cell development

Arginine methylation of SmB is required for Drosophila germ cell development

A Genomewide RNAi Screen for Genes That Affect the Stability, Distribution and Function of P Granules in Caenorhabditis elegans

Sm proteins specify germ cell fate by facilitatingoskarmRNA localization

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