Specialized germline P-bodies are required to specify germ cell fate in C. elegans embryos
Ontology highlight
ABSTRACT:
ORGANISM(S): Caenorhabditis elegans
PROVIDER: GSE211555 | GEO | 2022/10/04
REPOSITORIES: GEO
Similar Datasets
Project description:In animals with germ plasm, specification of the germline involves “germ granules”, cytoplasmic condensates that enrich maternal transcripts in the germline founder cells. In C. elegans embryos, P granules enrich maternal transcripts, but surprisingly P granules are not essential for germ cell fate specification. Here we have described a second condensate in the C. elegans germ plasm. Like canonical P-bodies found in somatic cells, “germline P-bodies” contain regulators of mRNA decapping and deadenylation and, in addition, the intrinsically-disordered proteins MEG-1 and MEG-2 and the TIS11-family RNA-binding protein POS-1. Embryos lacking meg-1 and meg-2 do not stabilize P-body components, miss-regulate POS-1 targets, miss-specify the germline founder cell, and do not develop a germline. Our findings suggest that specification of the germ line involves at least two distinct condensates that independently enrich and regulate maternal mRNAs in the germline founder cells.
2022-10-05 | PXD036610 | Pride
Project description:Ribonucleoprotein (RNP) granules are the most common membrane-less biomolecular condensates. However, the mechanisms underlying their assembly are largely unknown. The aggregation of germ plasm determines the fate of primordial germ cells (PGCs) and serves as a model for RNP granule assembly. Here, we show that maternal RNA binding protein Rbm24a is the key factor governing specific sorting of mRNAs. Mechanistically, Rbm24a complexes with Buc and interacts to dictate the specific grasp of germ plasm mRNAs into phase-separated condensates. Germ plasm particles lacking Rbm24a and mRNAs fail to undergo kinesin-dependent transport towards the cleavage furrows where small granules fuse into large aggregates. Therefore, the loss of maternal Rbm24a causes a complete degradation of germ plasm and the disappearance of PGCs. These findings demonstrate that Rbm24a functions as a nucleating organizer of the germ plasm, highlighting an emerging mechanism for RNA-binding proteins in reading and recruiting RNA components into the phase-separated protein scaffold.
2024-10-27 | GSE279756 | GEO
Project description:In C. elegans nematodes, components of liquid-like germ granules were shown to be required for transgenerational small RNA inheritance. Surprisingly, we show here that mutants with defective germ granules can nevertheless inherit potent small RNA-based silencing responses, but some of the mutants lose this ability after many generations of homozygosity. Animals mutated in pptr-1, which is required for stabilization of P granules in the early embryo, display extraordinarily strong heritable RNAi responses, lasting for tens of generations. Intriguingly, the RNAi capacity of descendants derived from mutants defective in the core germ granules proteins MEG-3 and MEG-4 is determined by the genotype of the ancestors, and changes transgenerationally. Further, whether the meg-3/4 mutant alleles were present in the paternal or maternal lineages lead to different transgenerational consequences. Small RNA inheritance, rather than maternal contribution of the germ granules themselves, mediates the transgenerational defects in RNAi of meg-3/4 mutants and their progeny. Accordingly, germ granule defects lead to heritable genome-wide mis-expression of endogenous small RNAs. Upon disruption of germ granules, hrde-1 mutants can inherit RNAi although HRDE-1 was previously thought to be absolutely required for RNAi inheritance. We propose that germ granules sort and shape the RNA pool, and that small RNA inheritance maintains this activity for multiple generations.
2019-07-31 | GSE128112 | GEO
Project description:RNA granules are cellular condensates that contain RNAs and proteins. The mechanism that drive the recruitment of many mRNAs to RNA granules are not fully understood. Here we characterize the assembly and transcriptome of the germ (P) granules of C. elegans. We find that mRNAs are recruited into P granules by condensation with the intrinsically-disordered protein MEG-3. MEG-3 binds ~500 mRNAs in C. elegans embryos in a sequence-independent manner that favors mRNAs with low ribosome coverage. Translational stress causes additional mRNAs to localize to P granules and translational activation correlates with P granule exit for two mRNAs coding for germ cell fate regulators. MEG-3/RNA condensates assembled in vitro are gel-like and trap mRNAs in a non-dynamic state. Our observations reveal similarities between P granules and stress granules and identify gelation with intrinsically-disordered proteins as a sequence-independent mechanism to enrich low-translation mRNAs in RNA granules
2019-12-01 | GSE139880 | GEO
Project description:RNA granules are cellular condensates that contain RNAs and proteins. The mechanism that drive the recruitment of many mRNAs to RNA granules are not fully understood. Here we characterize the assembly and transcriptome of the germ (P) granules of C. elegans. We find that mRNAs are recruited into P granules by condensation with the intrinsically-disordered protein MEG-3. MEG-3 binds ~500 mRNAs in C. elegans embryos in a sequence-independent manner that favors mRNAs with low ribosome coverage. Translational stress causes additional mRNAs to localize to P granules and translational activation correlates with P granule exit for two mRNAs coding for germ cell fate regulators. MEG-3/RNA condensates assembled in vitro are gel-like and trap mRNAs in a non-dynamic state. Our observations reveal similarities between P granules and stress granules and identify gelation with intrinsically-disordered proteins as a sequence-independent mechanism to enrich low-translation mRNAs in RNA granules
2019-12-01 | GSE139879 | GEO
Project description:RNA granules are cellular condensates that contain RNAs and proteins. The mechanism that drive the recruitment of many mRNAs to RNA granules are not fully understood. Here we characterize the assembly and transcriptome of the germ (P) granules of C. elegans. We find that mRNAs are recruited into P granules by condensation with the intrinsically-disordered protein MEG-3. MEG-3 binds ~500 mRNAs in C. elegans embryos in a sequence-independent manner that favors mRNAs with low ribosome coverage. Translational stress causes additional mRNAs to localize to P granules and translational activation correlates with P granule exit for two mRNAs coding for germ cell fate regulators. MEG-3/RNA condensates assembled in vitro are gel-like and trap mRNAs in a non-dynamic state. Our observations reveal similarities between P granules and stress granules and identify gelation with intrinsically-disordered proteins as a sequence-independent mechanism to enrich low-translation mRNAs in RNA granules
2019-12-01 | GSE139878 | GEO
Project description:Germ granules are biomolecular condensates that promote germ cell totipotency in most, if not all, animals. In C. elegans, MEG-3 and MEG-4 are two intrinsically disordered proteins that are redundantly required for the phase separations that drive germ granule assembly in germline blastomeres. Here, we show that animals lacking MEG-3/4 exhibit defects in dsRNA-mediated gene silencing (RNAi) that are due, at least in part, to defects in systemic RNAi. Interestingly, these RNAi defects are transgenerationally disconnected from meg-3/4 genotype: RNAi defects do not arise until 5-9 generations after animals become mutant for meg-3/4, and RNAi defects persist for 9-11 generations after meg-3/4 genotype is restored to wild type. Similar non-Mendelian patterns of inheritance are associated with other mutations that disrupt germ granule formation, indicating that germ granule disruption is the likely cause of genotype/phenotype disconnects. Loss of germ granules is associated with the production of aberrant populations of endogenous siRNAs, which, remarkably, are propagated for ≅10 generations in wild-type descendants of animals that lacked germ granules. sid-1, which encodes a factor required for systemic RNAi in C. elegans, is inappropriately and heritably silenced by aberrantly expressed sid-1 endogenous siRNAs, suggesting that transgenerational silencing of sid-1 likely underlies the heritable defect in RNAi. We conclude that one function of germ granules is to organize RNA-based epigenetic inheritance pathways and that failure to assemble germ granules has consequences that persist across many generations.
2019-08-08 | GSE134683 | GEO
Project description:Xenopus primordial germ cells (PGCs) are determined by the presence of maternally derived germ plasm. Germ plasm components both protect PGCs from somatic differentiation and begin a unique gene expression program. Segregation of the germline from the endodermal lineage occurs during gastrulation and PGCs subsequently initiate zygotic transcription. However, the gene-networks that operate to both preserve the potential for totipotency and promote germline differentiation are poorly understood. Here, we utilized RNA-sequencing analysis to comprehensively interrogate PGC and neighboring endoderm cell RNAs after lineage segregation. We identified 1,865 transcripts enriched in PGCs compared to endoderm cells. Over 50% of maternal, vegetally-enriched transcripts were enriched in the PGC transcriptome, including sox7. PGC-directed sox7 knockdown and over-expression studies revealed an early requirement for sox7 in proper germ plasm localization, zygotic transcription, and PGC number. We identified oct60 as the most highly expressed and enriched OCT3/4 homologue in PGCs. Lastly, we compared the Xenopus PGC transcriptome with human PGC transcripts and showed that 80% of transcripts are conserved, identifying Xenopus as a relevant model system for understanding the gene-networks necessary for human germline development.
2017-08-01 | GSE102047 | GEO
Project description:P granules in C. elegans are required for fertility and function to maintain germ cell identity and pluripotency. Sterility in the absence of P granules is often accompanied by the mis-expression of soma-specific proteins and the initiation of somatic differentiation in germ cells. To investigate whether this is caused by the accumulation of somatic transcripts, we performed mRNA-seq on dissected germlines with and without P granules. Strikingly, we found that somatic transcripts do not increase in the young adult germline when P granules are impaired. Instead, we found that impairing P granules causes sperm-specific mRNAs to become highly overexpressed. This includes the accumulation of major sperm protein (MSP) transcripts in germ cells, a phenotype that is suppressed by feminization of the germline. A core component of P granules, the endo-siRNA-binding Argonaute protein CSR-1, has recently been ascribed with the ability to license transcripts for germline expression. However, impairing CSR-1 has very little effect on the accumulation of its mRNA targets. Instead, we found that CSR-1 functions with P granules to prevent MSP and sperm-specific mRNAs from being transcribed in the hermaphrodite germline. These findings suggest that P granules protect germline integrity through two different mechanisms, by 1) preventing the inappropriate expression of somatic proteins at the level of translational regulation, and by 2) functioning with CSR-1 to limit the domain of sperm-specific expression at the level of transcription. Four biological replicates of each condition (empty vector control, P granule RNAi, and CSR-1 RNAi germlines) were collected for total RNA.
2015-05-20 | E-GEOD-67954 | biostudies-arrayexpress
Project description:Germ granules are membrane-less organelles essential for small RNA biogenesis and germline development. Among the conserved properties of germ granules is their association with the nuclear membrane. Recent studies demonstrated that LOTUS domain proteins, EGGD-1 and EGGD-2 (also known as MIP-1 and MIP-2 respectively), promote the formation of perinuclear germ granules in C. elegans. This finding presents a unique opportunity to evaluate the significance of perinuclear localization of germ granules. Here we show that loss of eggd-1 causes the coalescence of germ granules and formation of abnormal cytoplasmic aggregates. Impairment of perinuclear granules affects certain germline classes of small RNAs including Piwi-interacting RNAs. Transcriptome profiling reveals overexpression of spermatogenic and cuticle-related genes in eggd-1 hermaphrodites. We further demonstrate that disruption of germ granules activates HLH-30-mediated transcriptional program in somatic tissues. Collectively, our findings underscore the essential role of EGGD-1 in germ granule organization and reveal an unexpected germ granule-to-soma communication.
2023-07-20 | GSE228858 | GEO