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Arginine methylation of Piwi proteins catalysed by dPRMT5 is required for Ago3 and Aub stability.

Kirino Y, Kim N, de Planell-Saguer M, Khandros E, Chiorean S, Klein PS, Rigoutsos I, Jongens TA, Mourelatos Z - Nat. Cell Biol. (2009)

Bottom Line: We found that Piwi proteins are expressed in Xenopus oocytes and we identified numerous Xenopus piRNAs.Loss of dPRMT5 activity led to a reduction in the levels of piRNAs, Ago3 and Aub proteins, and accumulation of retrotransposons in the Drosophila ovary.Our findings underscore the significance of sDMA modification of Piwi proteins in the germline and suggest an interacting pathway of genes that are required for piRNA function and PGC specification.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Laboratory Medicine, Division of Neuropathology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.

ABSTRACT
Piwi family proteins are essential for germline development and bind piwi-interacting RNAs (piRNAs). The grandchildless gene aub of Drosophila melanogaster encodes the piRNA-binding protein Aubergine (Aub), which is essential for formation of primordial germ cells (PGCs). Here we report that Piwi family proteins of mouse, Xenopus laevis and Drosophila contain symmetrical dimethylarginines (sDMAs). We found that Piwi proteins are expressed in Xenopus oocytes and we identified numerous Xenopus piRNAs. We report that the Drosophila homologue of protein methyltransferase 5 (dPRMT5, csul/dart5), which is also the product of a grandchildless gene, is required for arginine methylation of Drosophila Piwi, Ago3 and Aub proteins in vivo. Loss of dPRMT5 activity led to a reduction in the levels of piRNAs, Ago3 and Aub proteins, and accumulation of retrotransposons in the Drosophila ovary. Our studies explain the relationship between aub and dPRMT5 (csul/dart5) genes by demonstrating that dPRMT5 is the enzyme that methylates Aub. Our findings underscore the significance of sDMA modification of Piwi proteins in the germline and suggest an interacting pathway of genes that are required for piRNA function and PGC specification.

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Proposed classification for selected Drosophila melanogaster grandchildless genes
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Figure 5: Proposed classification for selected Drosophila melanogaster grandchildless genes

Mentions: Germ cell (PGC) formation in Drosophila requires that cytoplasmic determinants are localized to the posterior pole of the embryo 32 (Figure 5, left panel). Genetic screens have identified grandchildless maternal genes that are required for PGC specification and invariably the protein or RNA products of these genes are concentrated in the pole plasm and are incorporated into the PGCs 32. Among these genes are Aub4, dPRMT5 (csul, dart5) 5, 6, and its cofactor valois33 and tudor34, whose protein product contains eleven tudor domains 35. We tested the localization of Aub in csul oocytes by confocal microscopy. Representative results are presented in Figure 4e and show that the levels of Aub in the pole plasm of stage 10 egg chambers are markedly reduced. Western blotting reveals marked reduction of Aub protein levels in csul ovaries (Figure 4a) while confocal microscopy shows that Aub levels are subtly reduced in early stage egg chambers (Figure 4d) but markedly reduced in later stage egg chambers (Figure 4e), suggesting that lack of sDMAs affects Aub levels at later stages in oogenesis.


Arginine methylation of Piwi proteins catalysed by dPRMT5 is required for Ago3 and Aub stability.

Kirino Y, Kim N, de Planell-Saguer M, Khandros E, Chiorean S, Klein PS, Rigoutsos I, Jongens TA, Mourelatos Z - Nat. Cell Biol. (2009)

Proposed classification for selected Drosophila melanogaster grandchildless genes
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2746449&req=5

Figure 5: Proposed classification for selected Drosophila melanogaster grandchildless genes
Mentions: Germ cell (PGC) formation in Drosophila requires that cytoplasmic determinants are localized to the posterior pole of the embryo 32 (Figure 5, left panel). Genetic screens have identified grandchildless maternal genes that are required for PGC specification and invariably the protein or RNA products of these genes are concentrated in the pole plasm and are incorporated into the PGCs 32. Among these genes are Aub4, dPRMT5 (csul, dart5) 5, 6, and its cofactor valois33 and tudor34, whose protein product contains eleven tudor domains 35. We tested the localization of Aub in csul oocytes by confocal microscopy. Representative results are presented in Figure 4e and show that the levels of Aub in the pole plasm of stage 10 egg chambers are markedly reduced. Western blotting reveals marked reduction of Aub protein levels in csul ovaries (Figure 4a) while confocal microscopy shows that Aub levels are subtly reduced in early stage egg chambers (Figure 4d) but markedly reduced in later stage egg chambers (Figure 4e), suggesting that lack of sDMAs affects Aub levels at later stages in oogenesis.

Bottom Line: We found that Piwi proteins are expressed in Xenopus oocytes and we identified numerous Xenopus piRNAs.Loss of dPRMT5 activity led to a reduction in the levels of piRNAs, Ago3 and Aub proteins, and accumulation of retrotransposons in the Drosophila ovary.Our findings underscore the significance of sDMA modification of Piwi proteins in the germline and suggest an interacting pathway of genes that are required for piRNA function and PGC specification.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Laboratory Medicine, Division of Neuropathology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.

ABSTRACT
Piwi family proteins are essential for germline development and bind piwi-interacting RNAs (piRNAs). The grandchildless gene aub of Drosophila melanogaster encodes the piRNA-binding protein Aubergine (Aub), which is essential for formation of primordial germ cells (PGCs). Here we report that Piwi family proteins of mouse, Xenopus laevis and Drosophila contain symmetrical dimethylarginines (sDMAs). We found that Piwi proteins are expressed in Xenopus oocytes and we identified numerous Xenopus piRNAs. We report that the Drosophila homologue of protein methyltransferase 5 (dPRMT5, csul/dart5), which is also the product of a grandchildless gene, is required for arginine methylation of Drosophila Piwi, Ago3 and Aub proteins in vivo. Loss of dPRMT5 activity led to a reduction in the levels of piRNAs, Ago3 and Aub proteins, and accumulation of retrotransposons in the Drosophila ovary. Our studies explain the relationship between aub and dPRMT5 (csul/dart5) genes by demonstrating that dPRMT5 is the enzyme that methylates Aub. Our findings underscore the significance of sDMA modification of Piwi proteins in the germline and suggest an interacting pathway of genes that are required for piRNA function and PGC specification.

Show MeSH