Xenopus Xpat protein is a major component of germ plasm and may function in its organisation and positioning

Machado, Rachel J.; Moore, Wendy; Hames, Richard; Houliston, Evelyn; Chang, Patrick; King, Mary Lou; Woodland, Hugh R.

doi:10.1016/j.ydbio.2005.08.044

Cited by 49 publications

(63 citation statements)

References 60 publications

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“…No differences were detected in the external development of embryos injected with either Nanos1-MO or Nanos1-Ctrl-MO, indicating the lack of toxicity of the MOs used. The fate of PGCs in embryos depleted of Nanos1 activity was followed by whole-mount in situ hybridization (WISH) with Xpat probe, a specific marker for PGCs (Hudson and Woodland, 1998;Machado et al, 2005). Significant differences in numbers were detected in the experimental population of PGCs starting at tailbud stage 26, with a dramatic decline by stage 35/36 (Fig.…”

Section: Embryos Depleted Of Nanos1 Are Deficient In Pgcsmentioning

confidence: 99%

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XenopusNanos1 is required to prevent endoderm gene expression and apoptosis in primordial germ cells

2012

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Nanos is expressed in multipotent cells, stem cells and primordial germ cells (PGCs) of organisms as diverse as jellyfish and humans. It functions together with Pumilio to translationally repress targeted mRNAs. Here we show by loss-of-function experiments that Xenopus Nanos1 is required to preserve PGC fate. Morpholino knockdown of maternal Nanos1 resulted in a striking decrease in PGCs and a loss of germ cells from the gonads. Lineage tracing and TUNEL staining reveal that Nanos1-deficient PGCs fail to migrate out of the endoderm. They appear to undergo apoptosis rather than convert to normal endoderm. Whereas normal PGCs do not become transcriptionally active until neurula, Nanos1-depleted PGCs prematurely exhibit a hyperphosphorylated RNA polymerase II C-terminal domain at the midblastula transition. Furthermore, they inappropriately express somatic genes characteristic of endoderm regulated by maternal VegT, including Xsox17α, Bix4, Mixer, GATA4 and Edd. We further demonstrate that Pumilio specifically binds VegT RNA in vitro and represses, along with Nanos1, VegT translation within PGCs. Repressed VegT RNA in wild-type PGCs is significantly less stable than VegT in Nanos1-depleted PGCs. Our data indicate that maternal VegT RNA is an authentic target of Nanos1/Pumilio translational repression. We propose that Nanos1 functions to translationally repress RNAs that normally specify endoderm and promote apoptosis, thus preserving the germline.

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Section: Embryos Depleted Of Nanos1 Are Deficient In Pgcsmentioning

confidence: 99%

“…Do PGCs depleted of Nanos1 activity now mistakenly initiate endoderm specification and thus lose Xpat expression (Machado et al, 2005)? To explore this possibility, we isolated PGCs from uninjected, Nanos1-Ctrl-MO-or Nanos1-MO-injected embryos.…”

Section: Research Articlementioning

confidence: 99%

XenopusNanos1 is required to prevent endoderm gene expression and apoptosis in primordial germ cells

2012

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“…Because Dnd1 is an RNA-binding protein and GP contains germline determinants (Tada et al, 2012), we speculate some RNA stored in GP before MBT might be carried to the perinuclear region and the nucleus with Dnd1, and trigger germline specification after MBT. Interestingly, Dnd1 and Xpat exhibit similar behavior (Machado et al, 2005). To identify the Dnd1 GP localization signal, we constructed deleted mutants of Dnd1 coupled with mCherry and compared their GP localization at stage 8 ( Fig.…”

Section: Results and Conclusionmentioning

confidence: 99%

“…However, gene expression is repressed in PGCs at MBT, so PGC specification likely occurs later (Venkatarama et al, 2010). Xpat protein, a GP component, moves from the cortex to the perinuclear region and then enters the nucleus (Machado et al, 2005). These observations suggest that some signal from GP to the nucleus is required for PGC specification.…”

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confidence: 98%

Intracellular localizations of the Dead End protein in Xenopus primordial germ cells

Taguchi

Watanabe²,

Orii³

2014

Int. J. Dev. Biol.

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We investigated the intracellular localization of Xenopus Dead end protein (Dnd1) in primordial germ cells during early development by expressing the tagged protein in transgenic Xenopus embryos, with the germ plasm visualized. Dnd1 initially localized to the germ plasm in the cortex, moved to the perinuclear region together with the germ plasm after the midblastula transition, and then entered the nucleus. Using Dnd1 deletion mutants, we identified two distinct but overlapping regions of Dnd1 that were responsible for localization to either the germ plasm or nucleus. These Dnd1 regions appeared to function in primordial germ cell-and stage-specific manners. KEY WORDS: Dnd1, germline, germ plasm, nuage, nuclear localization signal, RNA-binding proteinThe Xenopus germline is specified by inheriting a special cytoplasm, germ plasm (GP), associated with the vegetal cortex of the egg. We demonstrated that the GP was sufficient for germline specification (Tada et al., 2012). It is divided almost equally into daughter blastomeres until the 4-cell stage and is then distributed unequally to one daughter blastomere at each successive cleavage until stage 9 (Whitington and Dixon, 1975). Subsequently, it moves from the cortex to the perinuclear region and is distributed equally into two daughter primordial germ cells (PGCs). Midblastula transition (MBT), when zygotic genes begin to be expressed in most blastomeres, is observed around stage 9. However, gene expression is repressed in PGCs at MBT, so PGC specification likely occurs later (Venkatarama et al., 2010). Xpat protein, a GP component, moves from the cortex to the perinuclear region and then enters the nucleus (Machado et al., 2005). These observations suggest that some signal from GP to the nucleus is required for PGC specification.Dead end (dnd) encoding an RNA-binding protein with an RNA recognition motif (RRM) has been identified as a germlinespecific gene in vertebrates including zebrafish, Xenopus and mice (Weidinger et al., 2003). In Xenopus, the dnd1 transcript is a GP component and is required for PGC migration (Horvay et al., 2006). Furthermore, mouse dnd1 is responsible for the Ter mutant, which causes high frequency teratoma generation in a particular genetic background (Youngren et al., 2005). Several reports have described the intracellular localization of Dead end protein; in chicks Dnd protein is present in the nuclei of PGCs and mature male germ cells (Aramaki et al., 2009). In mice, two isoforms, DND1a and DND1b, were identified and localized to the nucleus and cytoplasm when Int. J. Dev. Biol. 58: 793-798 (2014) Abbreviations used in this paper: Dnd, dead end protein; GP, germ plasm; GPS, germ plasm localization signal; PGC, primordial germ cell.expressed in HeLa and COS-7 cells, respectively (Bhattacharya et al., 2007). In zebrafish, Dnd was localized to germ cell granules (GCGs, probably equivalent to Xenopus GP) in the perinuclear region of PGCs after MBT. Interestingly, this localization was dependent upon the RNA recognition motif...

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“…In Xenopus, germ plasm research is mostly focused on processes during oogenesis [49][50][51]. However, among vertebrates that specify their germ cells through inheritance of germ plasm, there are a numerous studies in the zebraish.…”

Section: Zebraish As a Model Organism To Study Germ Cell Speciicationmentioning

confidence: 99%

Germ Cell Specification: The Evolution of a Recipe to Make Germ Cells

Krishnakumar¹,

Dosch²

2018

Germ Cell

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Multicellular species use gametes for their propagation. Gametes are formed from primordial germ cells (PGCs), which develop during embryogenesis. In some species, PGCs are speciied by the inheritance of a RNA granule known as germ plasm. During germ cell speciication, the germ plasm conveys a unique set of properties, e.g. the germ cell speciic meiotic cell cycle to the PGCs. Germ plasm assembly is controlled by independently evolving organizer proteins like Oskar in Drosophila or Bucky ball in zebraish. These organizers are intrinsically disordered proteins, which rapidly changed their amino acid sequence during evolution. A common recipe has emerged by studies on organizer proteins for animals that use germ plasm to specify their germline. Investigating the nature of these organizers might therefore provide a clue to germ cell speciication in other species, which are less accessible to molecular-genetic and embryological approaches. Moreover, we might understand how the irst metazoans modiied their existing cellular structures from unicellular eukaryotes to ensure their reproduction.

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Xenopus Xpat protein is a major component of germ plasm and may function in its organisation and positioning

Cited by 49 publications

References 60 publications

XenopusNanos1 is required to prevent endoderm gene expression and apoptosis in primordial germ cells

XenopusNanos1 is required to prevent endoderm gene expression and apoptosis in primordial germ cells

Intracellular localizations of the Dead End protein in Xenopus primordial germ cells

Germ Cell Specification: The Evolution of a Recipe to Make Germ Cells

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