The C. elegans MEX-1 protein is present in germline blastomeres and is a P granule component

Development ◽  
1997 ◽  
Vol 124 (3) ◽  
pp. 731-739 ◽  
Author(s):  
S. Guedes ◽  
J.R. Priess
Keyword(s):  
Germ Cells ◽  
Gene Products ◽  
Cytoplasmic Protein ◽  
Embryonic Cells ◽  
Nematode Caenorhabditis Elegans ◽  
P Granules ◽  
C Elegans ◽  
Cytoplasmic Structures ◽  
Fertilized Egg ◽  
Expression And Activity

In the nematode Caenorhabditis elegans, germ cells arise from early embryonic cells called germline blastomeres. Cytoplasmic structures called P granules are present in the fertilized egg and are segregated into each of the germline blastomeres during the first few cleavages of the embryo. Mutations in the maternally expressed gene mex-1 disrupt the segregation of P granules, prevent the formation of germ cells, and cause inappropriate patterns of somatic cell differentiation. We have cloned the mex-1 gene and determined the distribution pattern of the mex-1 gene products. The MEX-1 protein contains two copies of an unusual ‘finger’ domain also found in the PIE-1 protein of C. elegans. PIE-1 has been shown to be expressed in germline blastomeres, and is a component of P granules. We show here that MEX-1 also is present in germline blastomeres and is a P granule component, although MEX-1 is a cytoplasmic protein while PIE-1 is present in both the nucleus and cytoplasm. We further show that MEX-1 is required to restrict PIE-1 expression and activity to the germline blastomeres during the early embryonic cleavages.

Analysis of RNA associated with P granules in germ cells of C. elegans adults

Development ◽  
2001 ◽  
Vol 128 (8) ◽  
pp. 1287-1298 ◽  
Author(s):  
J.A. Schisa ◽  
J.N. Pitt ◽  
J.R. Priess
Keyword(s):  
Germ Cells ◽  
Rna Binding ◽  
Nuclear Surface ◽  
Binding Motifs ◽  
P Granules ◽  
C Elegans ◽  
Specific Mrnas ◽  
Tubulin Mrna ◽  
Protein Components ◽  
Cytoplasmic Structures

P granules are cytoplasmic structures of unknown function that are associated with germ nuclei in the C. elegans gonad, and are localized exclusively to germ cells, or germ cell precursors, throughout the life cycle. All the known protein components of P granules contain putative RNA-binding motifs, suggesting that RNA is involved in either the structure or function of the granules. However, no specific mRNAs have been identified within P granules in the gonad. We show here that P granules normally contain a low level of RNA, and describe conditions that increase this level. We present evidence that several, diverse mRNAs, including pos-1, mex-1, par-3, skn-1, nos-2 and gld-1 mRNA, are present at least transiently within P granules. In contrast, actin and tubulin mRNA and rRNA are either not present in P granules, or are present at relatively low levels. We show that pgl-1 and the glh (Vasa-related) gene family, which encode protein components of P granules, do not appear essential for RNA to concentrate in P granules; these proteins may instead function in events that are a prerequisite for RNAs to be transported efficiently from the nuclear surface.

scholarly journals Perinuclear P granules are the principal sites of mRNA export in adult C. elegans germ cells

Development ◽  
2010 ◽  
Vol 137 (8) ◽  
pp. 1305-1314 ◽  
Author(s):  
U. Sheth ◽  
J. Pitt ◽  
S. Dennis ◽  
J. R. Priess
Keyword(s):  
Germ Cells ◽  
Mrna Export ◽  
P Granules ◽  
C Elegans

scholarly journals Specification of the germline by Nanos-dependent down-regulation of the somatic synMuvB transcription factor LIN-15B

2017 ◽  
Author(s):  
Chih-Yung S. Lee ◽  
Tu Lu ◽  
Geraldine Seydoux
Keyword(s):  
Transcription Factor ◽  
Germ Cells ◽  
Rna Binding ◽  
Primordial Germ Cells ◽  
Somatic Cells ◽  
Rna Binding Protein ◽  
Dependent Manner ◽  
Embryonic Cells ◽  
C Elegans ◽  
Underlying Mechanisms

AbstractThe Nanos RNA-binding protein has been implicated in the specification of primordial germ cells (PGCs) in metazoans, but the underlying mechanisms remain poorly understood. We have profiled the transcriptome of PGCs lacking the nanos homologues nos-1 and nos-2 iC. elegans. nos-1nos-2 PGCs fail to silence hundreds of genes normally expressed in oocytes and somatic cells, a phenotype reminiscent of PGCs lacking the repressive PRC2 complex. The nos-1nos-2 phenotype depends on LIN-15B, a broadly expressed synMuvB class transcription factor known to antagonize PRC2 activity in somatic cells. LIN-15B is maternally-inherited by all embryonic cells and is down-regulated specifically in PGCs in a nos-1nos-2-dependent manner. Consistent with LIN-15B being a critical target of Nanos regulation, inactivation of maternal LIN-15B restores fertility to nos-1nos-2 mutants. These studies demonstrate a central role for Nanos in reprogramming the transcriptome of PGCs away from an oocyte/somatic fate by down-regulating an antagonist of PRC2 activity.

scholarly journals Tropomyosin and Troponin Are Required for Ovarian Contraction in the Caenorhabditis elegans Reproductive System

2004 ◽  
Vol 15 (6) ◽  
pp. 2782-2793 ◽  
Author(s):  
Kanako Ono ◽  
Shoichiro Ono
Keyword(s):  
Rna Interference ◽  
Caenorhabditis Elegans ◽  
Germ Cells ◽  
Reproductive System ◽  
Regulatory Mechanism ◽  
Striated Muscle ◽  
Troponin C ◽  
Nematode Caenorhabditis Elegans ◽  
C Elegans ◽  
Somatic Gonad

Ovulation in the nematode Caenorhabditis elegans is coordinated by interactions between the somatic gonad and germ cells. Myoepithelial sheath cells of the proximal ovary are smooth muscle-like cells, but the regulatory mechanism of their contraction is unknown. We show that contraction of the ovarian muscle requires tropomyosin and troponin, which are generally major actin-linked regulators of contraction of striated muscle. RNA interference of tropomyosin or troponin C caused sterility by inhibiting ovarian contraction that is required for expelling mature oocytes into the spermatheca where fertilization takes place, thus causing accumulation of endomitotic oocytes in the ovary. Tropomyosin and troponin C were associated with actin filaments in the myoepithelial sheath, and the association of troponin C with actin was dependent on tropomyosin. A mutation in the actin depolymerizing factor/cofilin gene suppressed the ovulation defects by RNA interference of tropomyosin or troponin C. These results strongly suggest that tropomyosin and troponin are the actin-linked regulators for contraction of ovarian muscle in the C. elegans reproductive system.

scholarly journals P granules protect RNA interference genes from silencing by piRNAs

2019 ◽  
Author(s):  
John Paul T. Ouyang ◽  
Andrew Folkmann ◽  
Lauren Bernard ◽  
Chih-Yung Lee ◽  
Uri Seroussi ◽  
...  
Keyword(s):  
Rna Interference ◽  
Germ Cells ◽  
Small Rnas ◽  
Primordial Germ Cells ◽  
Safe Harbor ◽  
Wild Type ◽  
P Granules ◽  
C Elegans ◽  
Rna Biogenesis ◽  
Endogenous Genes

SUMMARYP granules are perinuclear condensates in C. elegans germ cells proposed to serve as hubs for self/non-self RNA discrimination by Argonautes. We report that a mutant (meg-3 meg-4) that does not assemble P granules in primordial germ cells loses competence for RNA-interference over several generations and accumulates silencing small RNAs against hundreds of endogenous genes, including the RNA-interference genes rde-11 and sid-1. In wild-type, rde-11 and sid-1 transcripts are heavily targeted by piRNAs, accumulate in P granules, but maintain expression. In the primordial germ cells of meg-3 meg-4 mutants, rde-11 and sid-1 transcripts disperse in the cytoplasm with the small RNA biogenesis machinery, become hyper-targeted by secondary sRNAs, and are eventually silenced. Silencing requires the PIWI-class Argonaute PRG-1 and the nuclear Argonaute HRDE-1 that maintains trans-generational silencing of piRNA targets. These observations support a “safe harbor” model for P granules in protecting germline transcripts from piRNA-initiated silencing.

Perinuclear P granules are the principal sites of mRNA export in adult C. elegans germ cells

2010 ◽  
Vol 123 (8) ◽  
pp. e1-e1
Author(s):  
U. Sheth ◽  
J. Pitt ◽  
S. Dennis ◽  
J. R. Priess
Keyword(s):  
Germ Cells ◽  
Mrna Export ◽  
P Granules ◽  
C Elegans

How do histone modifications contribute to transgenerational epigenetic inheritance in C. elegans?

2020 ◽  
Vol 48 (3) ◽  
pp. 1019-1034 ◽  
Author(s):  
Rachel M. Woodhouse ◽  
Alyson Ashe
Keyword(s):  
Histone Modifications ◽  
Molecular Mechanisms ◽  
Epigenetic Inheritance ◽  
Nematode Caenorhabditis Elegans ◽  
Histone Methyltransferases ◽  
Transgenerational Epigenetic Inheritance ◽  
C Elegans ◽  
Recent Developments ◽  
Gene Regulatory

Gene regulatory information can be inherited between generations in a phenomenon termed transgenerational epigenetic inheritance (TEI). While examples of TEI in many animals accumulate, the nematode Caenorhabditis elegans has proven particularly useful in investigating the underlying molecular mechanisms of this phenomenon. In C. elegans and other animals, the modification of histone proteins has emerged as a potential carrier and effector of transgenerational epigenetic information. In this review, we explore the contribution of histone modifications to TEI in C. elegans. We describe the role of repressive histone marks, histone methyltransferases, and associated chromatin factors in heritable gene silencing, and discuss recent developments and unanswered questions in how these factors integrate with other known TEI mechanisms. We also review the transgenerational effects of the manipulation of histone modifications on germline health and longevity.

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