PAR-2 is asymmetrically distributed and promotes association of P granules and PAR-1 with the cortex in C. elegans embryos

Development ◽  
1996 ◽  
Vol 122 (10) ◽  
pp. 3075-3084 ◽  
Author(s):  
L. Boyd ◽  
S. Guo ◽  
D. Levitan ◽  
D.T. Stinchcomb ◽  
K.J. Kemphues
Keyword(s):  
Cell Cycle ◽  
Germ Line ◽  
Cell Cortex ◽  
Asymmetric Distribution ◽  
Cell Stage ◽  
Posterior Cortex ◽  
P Granules ◽  
C Elegans ◽  
Cortical Localization ◽  
The One

The par genes participate in the process of establishing cellular asymmetries during the first cell cycle of Caenorhabditis elegans development. The par-2 gene is required for the unequal first cleavage and for asymmetries in cell cycle length and spindle orientation in the two resulting daughter cells. We have found that the PAR-2 protein is present in adult gonads and early embryos. In gonads, the protein is uniformly distributed at the cell cortex, and this subcellular localization depends on microfilaments. In the one-cell embryo, PAR-2 is localized to the posterior cortex and is partitioned into the posterior daughter, P1, at the first cleavage. PAR-2 exhibits a similar asymmetric cortical localization in P1, P2, and P3, the asymmetrically dividing blastomeres of germ line lineage. This distribution in embryos is very similar to that of PAR-1 protein. By analyzing the distribution of the PAR-2 protein in various par mutant backgrounds we found that proper asymmetric distribution of PAR-2 depends upon par-3 activity but not upon par-1 or par-4. par-2 activity is required for proper cortical localization of PAR-1 and this effect requires wild-type par-3 gene activity. We also find that, although par-2 activity is not required for posterior localization of P granules at the one-cell stage, it is required for proper cortical association of P granules in P1.

scholarly journals P granules extend the nuclear pore complex environment in the C. elegans germ line

2011 ◽  
Vol 192 (6) ◽  
pp. 939-948 ◽  
Author(s):  
Dustin L. Updike ◽  
Stephanie J. Hachey ◽  
Jeremy Kreher ◽  
Susan Strome
Keyword(s):  
Nuclear Pore Complex ◽  
Germ Plasm ◽  
Germ Line ◽  
Hydrophobic Interactions ◽  
Nuclear Periphery ◽  
Size Exclusion ◽  
Nuclear Pore ◽  
Complex Environment ◽  
P Granules ◽  
C Elegans

The immortal and totipotent properties of the germ line depend on determinants within the germ plasm. A common characteristic of germ plasm across phyla is the presence of germ granules, including P granules in Caenorhabditis elegans, which are typically associated with the nuclear periphery. In C. elegans, nuclear pore complex (NPC)–like FG repeat domains are found in the VASA-related P-granule proteins GLH-1, GLH-2, and GLH-4 and other P-granule components. We demonstrate that P granules, like NPCs, are held together by weak hydrophobic interactions and establish a size-exclusion barrier. Our analysis of intestine-expressed proteins revealed that GLH-1 and its FG domain are not sufficient to form granules, but require factors like PGL-1 to nucleate the localized concentration of GLH proteins. GLH-1 is necessary but not sufficient for the perinuclear location of granules in the intestine. Our results suggest that P granules extend the NPC environment in the germ line and provide insights into the roles of the PGL and GLH family proteins.

Brief cytochalasin-induced disruption of microfilaments during a critical interval in 1-cell C. elegans embryos alters the partitioning of developmental instructions to the 2-cell embryo

Development ◽  
1990 ◽  
Vol 108 (1) ◽  
pp. 159-172 ◽  
Author(s):  
D.P. Hill ◽  
S. Strome
Keyword(s):  
Cell Cycle ◽  
Asymmetric Cell Division ◽  
Critical Time ◽  
Time Interval ◽  
Critical Interval ◽  
Cell Stage ◽  
C Elegans ◽  
Daughter Cells ◽  
Correct Pattern ◽  
Cell Embryo

We are investigating the involvement of the microfilament cytoskeleton in the development of early Caenorhabditis elegans embryos. We previously reported that several cytoplasmic movements in the zygote require that the microfilament cytoskeleton remain intact during a narrow time interval approximately three-quarters of the way through the first cell cycle. In this study, we analyze the developmental consequences of brief, cytochalasin D-induced microfilament disruption during the 1-cell stage. Our results indicate that during the first cell cycle microfilaments are important only during the critical time interval for the 2-cell embryo to undergo the correct pattern of subsequent divisions and to initiate the differentiation of at least 4 tissue types. Disruption of microfilaments during the critical interval results in aberrant division and P-granule segregation patterns, generating some embryos that we classify as ‘reverse polarity’, ‘anterior duplication’, and ‘posterior duplication’ embryos. These altered patterns suggest that microfilament disruption during the critical interval leads to the incorrect distribution of developmental instructions responsible for early pattern formation. The strict correlation between unequal division, unequal germ-granule partitioning, and the generation of daughter cells with different cell cycle periods observed in these embryos suggests that the three processes are coupled. We hypothesize that (1) an ‘asymmetry determinant’, normally located at the posterior end of the zygote, governs asymmetric cell division, germ-granule segregation, and the segregation of cell cycle timing elements during the first cell cycle, and (2) the integrity or placement of this asymmetry determinant is sensitive to microfilament disruption during the critical time interval.

scholarly journals Novel LOTUS-domain proteins are organizational hubs that recruit C. elegans Vasa to germ granules

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Patricia Giselle Cipriani ◽  
Olivia Bay ◽  
John Zinno ◽  
Michelle Gutwein ◽  
Hin Hark Gan ◽  
...  
Keyword(s):  
Rna Processing ◽  
Germ Line ◽  
Temperature Sensitive ◽  
Developmental Transitions ◽  
P Granules ◽  
C Elegans ◽  
Intrinsically Disordered ◽  
Meiotic Progression ◽  
Intrinsically Disordered Regions ◽  
Granule Growth

We describe MIP-1 and MIP-2, novel paralogous C. elegans germ granule components that interact with the intrinsically disordered MEG-3 protein. These proteins promote P granule condensation, form granules independently of MEG-3 in the postembryonic germ line, and balance each other in regulating P granule growth and localization. MIP-1 and MIP-2 each contain two LOTUS domains and intrinsically disordered regions and form homo- and heterodimers. They bind and anchor the Vasa homolog GLH-1 within P granules and are jointly required for coalescence of MEG-3, GLH-1, and PGL proteins. Animals lacking MIP-1 and MIP-2 show temperature-sensitive embryonic lethality, sterility, and mortal germ lines. Germline phenotypes include defects in stem cell self-renewal, meiotic progression, and gamete differentiation. We propose that these proteins serve as scaffolds and organizing centers for ribonucleoprotein networks within P granules that help recruit and balance essential RNA processing machinery to regulate key developmental transitions in the germ line.

scholarly journals DAF-18/PTEN inhibits germline zygotic gene activation during primordial germ cell quiescence

2020 ◽  
Author(s):  
Amanda L. Fry ◽  
Amy Webster ◽  
Rojin Chitrakar ◽  
L. Ryan Baugh ◽  
E. Jane Albert Hubbard
Keyword(s):  
Cell Cycle ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
Primordial Germ Cell ◽  
Gene Activation ◽  
Dependent Manner ◽  
Germline Gene ◽  
C Elegans ◽  
Zygotic Gene ◽  
Zygotic Gene Activation

AbstractQuiescence, an actively-maintained reversible state of cell cycle arrest, is not well understood. PTEN is one of the most frequently lost tumor suppressors in human cancers and regulates quiescence of stem cells and cancer cells. In C. elegans mutant for daf-18, the sole C. elegans PTEN ortholog, primordial germ cells (PGCs) divide inappropriately in starvation conditions, in a TOR-dependent manner. Here, we further investigated the role of daf-18 in maintaining PGC quiescence. We found that maternal or zygotic daf-18 is sufficient to maintain cell cycle quiescence, that daf-18 acts in the germ line and soma, and that daf-18 affects timing of PGC divisions in fed animals. Importantly, our results also implicate daf-18 in zygotic germline gene activation, though not in germline fate specification. However, TOR is less important to zygotic germline gene expression, suggesting that in the absence of food daf-18/PTEN prevents inappropriate germline zygotic gene activation and cell division by distinct mechanisms.

scholarly journals Proximity labeling identifies LOTUS domain proteins that promote the formation of perinuclear germ granules in C. elegans

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Ian F Price ◽  
Hannah L Hertz ◽  
Benjamin Pastore ◽  
Jillian Wagner ◽  
Wen Tang
Keyword(s):  
Germ Line ◽  
Nuclear Periphery ◽  
P Granules ◽  
C Elegans ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Germ Granules ◽  
Protein Components ◽  
Labeling Method ◽  
Disordered Regions

The germ line produces gametes that transmit genetic and epigenetic information to the next generation. Maintenance of germ cells and development of gametes require germ granules-well-conserved membraneless and RNA-rich organelles. The composition of germ granules is elusive owing to their dynamic nature and their exclusive expression in the germ line. Using C. elegans germ granule, called P granule, as a model system, we employed a proximity-based labeling method in combination with mass spectrometry to comprehensively define its protein components. This set of experiments identified over 200 proteins, many of which contain intrinsically disordered regions. An RNAi-based screen identified factors that are essential for P granule assembly, notably EGGD-1 and EGGD-2, two putative LOTUS-domain proteins. Loss of eggd-1 and eggd-2 results in separation of P granules from the nuclear envelope, germline atrophy and reduced fertility. We show that intrinsically disordered regions of EGGD-1 are required to anchor EGGD-1 to the nuclear periphery while its LOTUS domains are required to promote perinuclear localization of P granules. Together, our work expands the repertoire of P granule constituents and provides new insights into the role of LOTUS-domain proteins in germ granule organization.

scholarly journals Centrosome Aurora A gradient ensures a single PAR-2 polarity axis by regulating RhoGEF ECT-2 localization in C. elegans embryos

2018 ◽  
Author(s):  
Sukriti Kapoor ◽  
Sachin Kotak
Keyword(s):  
Spatial Information ◽  
Aurora A Kinase ◽  
Aurora A ◽  
Posterior Cortex ◽  
C Elegans ◽  
Local Inhibition ◽  
Cell Embryo ◽  
Polarity Establishment ◽  
The One ◽  
Cortical Contractility

AbstractThe proper establishment of the cell polarity is essential for development and morphogenesis. In the Caenorhabditis elegans one-cell embryo, a centrosome localized signal provides spatial information that is responsible for generating a single polarity axis. It is hypothesized that such a signal causes local inhibition of cortical actomyosin network in the vicinity of the centrosome. This pivotal event initiates symmetry breaking to direct partitioning of the partition defective proteins (PARs) in the one-cell embryo. However, the molecular nature of the centrosome regulated signal that impinges on the posterior cortex to bring upon cortical anisotropy in the actomyosin network and to promote polarity establishment remains elusive. Here, we discover that Aurora A kinase (AIR-1 in C. elegans) is essential for proper cortical contractility in the one-cell embryo. Loss of AIR-1 causes pronounced cortical contractions on the entire embryo surface during polarity establishment phase, and this creates more than one PAR-2 polarity axis. Moreover, we show that in the absence of AIR-1, centrosome positioning becomes dispensable in dictating the PAR-2 polarity axis. Interestingly, we identify that Rho Guanine Exchange Factor (GEF) ECT-2 acts downstream to AIR-1 to control excess contractility and notably AIR-1 loss affects ECT-2 cortical localization and thereby polarity establishment. Overall, our study unravels a novel insight whereby an evolutionarily conserved kinase Aurora A inhibits promiscuous PAR-2 domain formation and ensures singularity in the polarity establishment axis.

The C. elegans par-4 gene encodes a putative serine-threonine kinase required for establishing embryonic asymmetry

Development ◽  
2000 ◽  
Vol 127 (7) ◽  
pp. 1467-1475 ◽  
Author(s):  
J.L. Watts ◽  
D.G. Morton ◽  
J. Bestman ◽  
K.J. Kemphues
Keyword(s):  
Cell Cycle ◽  
Kinase Domain ◽  
Missense Mutations ◽  
Serine Threonine Kinase ◽  
Cell Stage ◽  
Threonine Kinase ◽  
C Elegans ◽  
Human Kinase ◽  
Early Embryos ◽  
Peutz Jeghers Syndrome

During the first cell cycle of Caenorhabditis elegans embryogenesis, asymmetries are established that are essential for determining the subsequent developmental fates of the daughter cells. The maternally expressed par genes are required for establishing this polarity. The products of several of the par genes have been found to be themselves asymmetrically distributed in the first cell cycle. We have identified the par-4 gene of C. elegans, and find that it encodes a putative serine-threonine kinase with similarity to a human kinase associated with Peutz-Jeghers Syndrome, LKB1 (STK11), and a Xenopus egg and embryo kinase, XEEK1. Several strong par-4 mutant alleles are missense mutations that alter conserved residues within the kinase domain, suggesting that kinase activity is essential for PAR-4 function. We find that the PAR-4 protein is present in the gonads, oocytes and early embryos of C. elegans, and is both cytoplasmically and cortically distributed. The cortical distribution begins at the late 1-cell stage, is more pronounced at the 2- and 4-cell stages and is reduced at late stages of embryonic development. We find no asymmetry in the distribution of PAR-4 protein in C. elegans embryos. The distribution of PAR-4 protein in early embryos is unaffected by mutations in the other par genes.

scholarly journals Probing and manipulating embryogenesis via nanoscale thermometry and temperature control

2020 ◽  
Vol 117 (26) ◽  
pp. 14636-14641 ◽  
Author(s):  
Joonhee Choi ◽  
Hengyun Zhou ◽  
Renate Landig ◽  
Hai-Yin Wu ◽  
Xiaofei Yu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Cell Communication ◽  
Cycle Duration ◽  
Cell Stage ◽  
C Elegans ◽  
Local Perturbations ◽  
Cell Division Timing ◽  
Nanoscale Thermometry

Understanding the coordination of cell-division timing is one of the outstanding questions in the field of developmental biology. One active control parameter of the cell-cycle duration is temperature, as it can accelerate or decelerate the rate of biochemical reactions. However, controlled experiments at the cellular scale are challenging, due to the limited availability of biocompatible temperature sensors, as well as the lack of practical methods to systematically control local temperatures and cellular dynamics. Here, we demonstrate a method to probe and control the cell-division timing inCaenorhabditis elegansembryos using a combination of local laser heating and nanoscale thermometry. Local infrared laser illumination produces a temperature gradient across the embryo, which is precisely measured by in vivo nanoscale thermometry using quantum defects in nanodiamonds. These techniques enable selective, controlled acceleration of the cell divisions, even enabling an inversion of division order at the two-cell stage. Our data suggest that the cell-cycle timing asynchrony of the early embryonic development inC. elegansis determined independently by individual cells rather than via cell-to-cell communication. Our method can be used to control the development of multicellular organisms and to provide insights into the regulation of cell-division timings as a consequence of local perturbations.

scholarly journals CGEF-1 and CHIN-1 Regulate CDC-42 Activity during Asymmetric Division in the Caenorhabditis elegans Embryo

2010 ◽  
Vol 21 (2) ◽  
pp. 266-277 ◽  
Author(s):  
Kraig T. Kumfer ◽  
Steven J. Cook ◽  
Jayne M. Squirrell ◽  
Kevin W. Eliceiri ◽  
Nina Peel ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Rho Gtpase ◽  
Maintenance Phase ◽  
Early Embryo ◽  
Cell Cortex ◽  
Nucleotide Exchange ◽  
Cell Stage ◽  
Nucleotide Exchange Factor ◽  
The One ◽  
Regulatory Loop

The anterior–posterior axis of the Caenorhabditis elegans embryo is elaborated at the one-cell stage by the polarization of the partitioning (PAR) proteins at the cell cortex. Polarization is established under the control of the Rho GTPase RHO-1 and is maintained by the Rho GTPase CDC-42. To understand more clearly the role of the Rho family GTPases in polarization and division of the early embryo, we constructed a fluorescent biosensor to determine the localization of CDC-42 activity in the living embryo. A genetic screen using this biosensor identified one positive (putative guanine nucleotide exchange factor [GEF]) and one negative (putative GTPase activating protein [GAP]) regulator of CDC-42 activity: CGEF-1 and CHIN-1. CGEF-1 was required for robust activation, whereas CHIN-1 restricted the spatial extent of CDC-42 activity. Genetic studies placed CHIN-1 in a novel regulatory loop, parallel to loop described previously, that maintains cortical PAR polarity. We found that polarized distributions of the nonmuscle myosin NMY-2 at the cell cortex are independently produced by the actions of RHO-1, and its effector kinase LET-502, during establishment phase and CDC-42, and its effector kinase MRCK-1, during maintenance phase. CHIN-1 restricted NMY-2 recruitment to the anterior during maintenance phase, consistent with its role in polarizing CDC-42 activity during this phase.

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