scholarly journals Diverse mechanisms regulate contractile ring assembly for cytokinesis in the two-cell C. elegans embryo

2022 ◽  
Author(s):  
Imge Ozugergin ◽  
Karina Mastronardi ◽  
Chris Law ◽  
Alisa Piekny
Keyword(s):  
Cell Types ◽  
Somatic Tissue ◽  
Ring Closure ◽  
Contractile Ring ◽  
C Elegans ◽  
Daughter Cells ◽  
The Core ◽  
Ring Assembly ◽  
Different Cell Types ◽  
Ring Position

Cytokinesis occurs at the end of mitosis due to the ingression of a contractile ring that cleaves the daughter cells. The core machinery regulating this crucial process is conserved among metazoans. Multiple pathways control ring assembly, but their contribution in different cell types is not known. We found that in the C. elegans embryo, AB and P1 cells fated to be somatic tissue and germline, respectively, have different cytokinesis kinetics supported by distinct myosin levels and organization. Through perturbation of RhoA or polarity regulators and the generation of tetraploid strains, we found that ring assembly is controlled by multiple fate-dependent factors that include myosin-levels, and mechanisms that respond to cell size. Active Ran coordinates ring position with the segregating chromatids in HeLa cells by forming an inverse gradient with importins that control the cortical recruitment of anillin. We found that the Ran pathway regulates anillin in AB cells, but functions differently in P1 cells. We propose that ring assembly delays in P1 cells caused by low myosin and Ran signaling coordinate the timing of ring closure with their somatic neighbours.

scholarly journals The Ran pathway uniquely regulates cytokinesis in cells with different fates in the early C. elegans embryo

2021 ◽  
Author(s):  
Imge Ozugergin ◽  
Karina Mastronardi ◽  
Chris Law ◽  
Alisa Piekny
Keyword(s):  
Cell Fate ◽  
Cell Types ◽  
Contractile Ring ◽  
C Elegans ◽  
Multiple Parameters ◽  
Daughter Cells ◽  
The Core ◽  
Cortical Patterning ◽  
Different Cell Types ◽  
In Cells

ABSTRACTCytokinesis occurs at the end of mitosis and occurs due to the ingression of a contractile ring that cleaves the daughter cells. This process is tightly controlled to prevent cell fate changes or aneuploidy, and the core machinery is highly conserved among metazoans. Multiple mechanisms regulate cytokinesis, but their requirement in different cell types is not known. Here, we show that differently fated AB and P1 cells in the early C. elegans embryo have unique cytokinesis kinetics supported by distinct levels and cortical patterning of myosin. Through perturbation of polarity regulators and the generation of stable tetraploid strains, we demonstrate that these differences depend on both cell fate and size. Additionally, these parameters could influence the Ran pathway, which coordinates the contractile ring with chromatin position, and controls cytokinesis differently in AB and P1 cells. Our findings demonstrate the need to consider multiple parameters when modeling ring kinetics.

scholarly journals Core-shell bioprinting as a strategy to apply differentiation factors in a spatially defined manner inside osteochondral tissue substitutes

2021 ◽  
Author(s):  
David Kilian ◽  
Silvia Cometta ◽  
Anne Bernhardt ◽  
Rania Taymour ◽  
Jonas Golde ◽  
...  
Keyword(s):  
Binding Capacity ◽  
Close Contact ◽  
Release Kinetics ◽  
Cell Types ◽  
Core Shell ◽  
The Core ◽  
Differentiation Factors ◽  
Local Supply ◽  
Osteochondral Tissue ◽  
Different Cell Types

Abstract One of the key challenges in osteochondral tissue engineering is to define specified zones with varying material properties, cell types and biochemical factors supporting locally adjusted differentiation into the osteogenic and chondrogenic lineage, respectively. Herein, extrusion-based core-shell bioprinting is introduced as a potent tool allowing a spatially defined delivery of cell types and differentiation factors TGF-β3 and BMP-2 in separated compartments of hydrogel strands, and, therefore, a local supply of matching factors for chondrocytes and osteoblasts. Ink development was based on blends of alginate and methylcellulose, in combination with varying concentrations of the nanoclay Laponite whose high affinity binding capacity for various molecules was exploited. Release kinetics of model molecules was successfully tuned by Laponite addition. Core-shell bioprinting was proven to generate well-oriented compartments within one strand as monitored by optical coherence tomography in a non-invasive manner. Chondrocytes and osteoblasts were applied each in the shell while the respective differentiation factors (TGF-β3, BMP-2) were provided by a Laponite-supported core serving as central factor depot within the strand, allowing directed differentiation of cells in close contact to the core. Experiments with bi-zonal constructs, comprising an osteogenic and a chondrogenic zone, revealed that the local delivery of the factors from the core reduces effects of these factors on the cells in the other scaffold zone. These observations prove the general suitability of the suggested system for co-differentiation of different cell types within a zonal construct.

A centrosome-associated antibody from Drosophila melanogaster reveals a new microtubule-dependent structure in the equatorial zone of Parascaris univalens embryos

1993 ◽  
Vol 106 (3) ◽  
pp. 719-730
Author(s):  
M. Jimenez ◽  
C. Goday
Keyword(s):  
Drosophila Melanogaster ◽  
Cytochalasin B ◽  
Cell Communication ◽  
Equatorial Zone ◽  
Contractile Ring ◽  
Daughter Cells ◽  
Ring Assembly ◽  
Single Body ◽  
A Cell ◽  
Cycle Dependent

The distribution of antigens to two antibodies (Bx63 and Rb188) that associate to Drosophila melanogaster centrosomes has been investigated in the nematode Parascaris. By western blot analysis both antibodies identify in Parascaris polypeptides of the same molecular mass as in Drosophila (Rb188 a 185 kDa antigen and Bx63 185 kDa and 66 kDa antigens). By immunocytochemistry we show that the centrosomes of Parascaris contain the 185 kDa antigen recognized by polyclonal Rb188 and monoclonal Bx63 antibodies. In addition, Bx63 reveals cytoplasmic midzone structures, not found in Drosophila, that display a cell cycle-dependent organization in embryos. These structures, which most probably contain the 66 kDa antigen revealed by Bx63, appear at the onset of anaphase as fibrillar-like structures that during anaphase form a ring-like structure encircling the equatorial plane of the blastomere. Before furrowing, the antigen participates in the formation of the midbody and associates with convergent polar microtubules. After blastomere division, Bx63 signal persists as a single body between the daughter cells. The analysis of chilled and nocodazole-treated embryos suggests that the localization of the midzone Bx63 antigen is dependent on non-kinetochore microtubules. Inhibition of furrowing by cytochalasin B shows that the antigen persists after the disassembly of microfilaments. Cytological observations of contractile ring and Bx63 ring assembly indicate that both structures do not simultaneously colocalize at the equatorial zone. The data suggest a spindle-dependent distribution of the Bx63 antigen during cytokinesis. We discuss the participation of this antigen in the organization of the midbody before furrowing, and consider the possible relevance of the midbody with respect to cell to cell communication during early development in nematodes.

scholarly journals A positive feedback-based mechanism for constriction rate acceleration during cytokinesis in C. elegans

2017 ◽  
Author(s):  
Renat N. Khaliullin ◽  
Rebecca A. Green ◽  
Linda Z. Shi ◽  
J. Sebastian Gomez-Cavazos ◽  
Michael W. Berns ◽  
...  
Keyword(s):  
Positive Feedback ◽  
Cell Biology ◽  
Unit Length ◽  
Mathematical Formulation ◽  
Ring Closure ◽  
Cortical Surface ◽  
Contractile Ring ◽  
Closure Rate ◽  
C Elegans ◽  
Rate Acceleration

ABSTRACTDuring cytokinesis, an equatorial actomyosin contractile ring constricts at a relatively constant overall rate despite its progressively decreasing size. Thus, the per-unit-length rate of ring closure increases as ring perimeter decreases. To understand this acceleration, we monitored cortical surface and ring component dynamics during the first division of the C. elegans embryo. We show that the polar cortex expands during ring constriction to provide the cortical surface area required for division. Polar expansion also allows ring myosin to compress cortical surface along the pole-to-pole axis, leading to a continuous flow of cortical surface into the ring. We propose that feedback between ring myosin and compression-driven cortical flow drives an exponential increase in the amount of ring myosin that maintains the high overall closure rate as ring perimeter decreases. We further show that an analytical mathematical formulation of the proposed feedback, called the Compression Feedback model, recapitulates the experimental observations.IMPACT STATEMENTDuring cytokinesis, positive feedback between myosin motors in the contractile ring and compression-driven cortical flow along the axis perpendicular to the ring drives constriction rate acceleration to ensure timely cell separation.MAJOR SUBJECT AREASCell biology, Computational and Systems Biology

scholarly journals Exploratory analysis of transposable elements expression in the C. elegans early embryo

2019 ◽  
Vol 20 (S9) ◽  
Author(s):  
Federico Ansaloni ◽  
Margherita Scarpato ◽  
Elia Di Schiavi ◽  
Stefano Gustincich ◽  
Remo Sanges
Keyword(s):  
Nervous System ◽  
Transposable Elements ◽  
Embryo Development ◽  
Cell Types ◽  
Early Embryo ◽  
Bioinformatics Pipeline ◽  
Early Embryo Development ◽  
C Elegans ◽  
Differentiated Cells ◽  
Different Cell Types

Abstract Background Transposable Elements (TE) are mobile sequences that make up large portions of eukaryote genomes. The functions they play within the complex cellular architecture are still not clearly understood, but it is becoming evident that TE have a role in several physiological and pathological processes. In particular, it has been shown that TE transcription is necessary for the correct development of mice embryos and that their expression is able to finely modulate transcription of coding and non-coding genes. Moreover, their activity in the central nervous system (CNS) and other tissues has been correlated with the creation of somatic mosaicisms and with pathologies such as neurodevelopmental and neurodegenerative diseases as well as cancers. Results We analyzed TE expression among different cell types of the Caenorhabditis elegans (C. elegans) early embryo asking if, where and when TE are expressed and whether their expression is correlated with genes playing a role in early embryo development. To answer these questions, we took advantage of a public C. elegans embryonic single-cell RNA-seq (sc-RNAseq) dataset and developed a bioinformatics pipeline able to quantify reads mapping specifically against TE, avoiding counting reads mapping on TE fragments embedded in coding/non-coding transcripts. Our results suggest that i) canonical TE expression analysis tools, which do not discard reads mapping on TE fragments embedded in annotated transcripts, may over-estimate TE expression levels, ii) Long Terminal Repeats (LTR) elements are mostly expressed in undifferentiated cells and might play a role in pluripotency maintenance and activation of the innate immune response, iii) non-LTR are expressed in differentiated cells, in particular in neurons and nervous system-associated tissues, and iv) DNA TE are homogenously expressed throughout the C. elegans early embryo development. Conclusions TE expression appears finely modulated in the C. elegans early embryo and different TE classes are expressed in different cell types and stages, suggesting that TE might play diverse functions during early embryo development.

scholarly journals Roles of Actin in the Morphogenesis of the Early Caenorhabditis elegans Embryo

2020 ◽  
Vol 21 (10) ◽  
pp. 3652
Author(s):  
Dureen Samandar Eweis ◽  
Julie Plastino
Keyword(s):  
Cell Division ◽  
Caenorhabditis Elegans ◽  
Asymmetric Cell Division ◽  
Cell Types ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Asymmetric Cell Divisions ◽  
C Elegans ◽  
Asymmetric Divisions ◽  
Different Cell Types

The cell shape changes that ensure asymmetric cell divisions are crucial for correct development, as asymmetric divisions allow for the formation of different cell types and therefore different tissues. The first division of the Caenorhabditis elegans embryo has emerged as a powerful model for understanding asymmetric cell division. The dynamics of microtubules, polarity proteins, and the actin cytoskeleton are all key for this process. In this review, we highlight studies from the last five years revealing new insights about the role of actin dynamics in the first asymmetric cell division of the early C. elegans embryo. Recent results concerning the roles of actin and actin binding proteins in symmetry breaking, cortical flows, cortical integrity, and cleavage furrow formation are described.

scholarly journals Cortical recruitment of centralspindlin and RhoA effectors during meiosis I of Caenorhabditiselegans primary spermatocytes

2021 ◽  
Vol 134 (3) ◽  
pp. jcs238543 ◽  
Author(s):  
Xiangchuan Wang ◽  
Dandan Zhang ◽  
Cunni Zheng ◽  
Shian Wu ◽  
Michael Glotzer ◽  
...  
Keyword(s):  
Cell Biology ◽  
Time Lapse ◽  
Contractile Ring ◽  
Cellular Division ◽  
C Elegans ◽  
Ring Assembly ◽  
Male Gametes ◽  
Spatiotemporal Regulation ◽  
Haploid Male ◽  
Meiosis I

ABSTRACTHaploid male gametes are produced through meiosis during gametogenesis. Whereas the cell biology of mitosis and meiosis is well studied in the nematode Caenorhabditis elegans, comparatively little is known regarding the physical division of primary spermatocytes during meiosis I. Here, we investigated this process using high-resolution time-lapse confocal microscopy and examined the spatiotemporal regulation of contractile ring assembly in C. elegans primary spermatocytes. We found that centralspindlin and RhoA effectors were recruited to the equatorial cortex of dividing primary spermatocytes for contractile ring assembly before segregation of homologous chromosomes. We also observed that perturbations shown to promote centralspindlin oligomerization regulated the cortical recruitment of NMY-2 and impacted the order in which primary spermatocytes along the proximal–distal axis of the gonad enter meiosis I. These results expand our understanding of the cellular division of primary spermatocytes into secondary spermatocytes during meiosis I.This article has an associated First Person interview with the first author of the paper.

scholarly journals Myosin concentration underlies cell size–dependent scalability of actomyosin ring constriction

2011 ◽  
Vol 195 (5) ◽  
pp. 799-813 ◽  
Author(s):  
Meredith E.K. Calvert ◽  
Graham D. Wright ◽  
Fong Yew Leong ◽  
Keng-Hwee Chiam ◽  
Yinxiao Chen ◽  
...  
Keyword(s):  
Filamentous Fungus ◽  
Mechanical Characteristics ◽  
Cell Types ◽  
Contractile Ring ◽  
C Elegans ◽  
Size Dependent ◽  
Wide Range ◽  
Similar Mode ◽  
Ring Constriction ◽  
Myosin Motors

In eukaryotes, cytokinesis is accomplished by an actomyosin-based contractile ring. Although in Caenorhabditis elegans embryos larger cells divide at a faster rate than smaller cells, it remains unknown whether a similar mode of scalability operates in other cells. We investigated cytokinesis in the filamentous fungus Neurospora crassa, which exhibits a wide range of hyphal circumferences. We found that N. crassa cells divide using an actomyosin ring and larger rings constricted faster than smaller rings. However, unlike in C. elegans, the total amount of myosin remained constant throughout constriction, and there was a size-dependent increase in the starting concentration of myosin in the ring. We predict that the increased number of ring-associated myosin motors in larger rings leads to the increased constriction rate. Accordingly, reduction or inhibition of ring-associated myosin slows down the rate of constriction. Because the mechanical characteristics of contractile rings are conserved, we predict that these findings will be relevant to actomyosin ring constriction in other cell types.

scholarly journals Architecture of the Pancreatic Islets and Endocrine Cell Arrangement in the Embryonic Pancreas of the Grass Snake (Natrix natrix L.). Immunocytochemical Studies and 3D Reconstructions

2021 ◽  
Vol 22 (14) ◽  
pp. 7601
Author(s):  
Magdalena Kowalska ◽  
Weronika Rupik
Keyword(s):  
Endocrine Cells ◽  
Developmental Stages ◽  
Cell Types ◽  
Dorsal Pancreas ◽  
The Core ◽  
Embryonic Pancreas ◽  
Grass Snake ◽  
D Cells ◽  
Different Cell Types ◽  
Early Developmental

During the early developmental stages of grass snakes, within the differentiating pancreas, cords of endocrine cells are formed. They differentiate into agglomerates of large islets flanked throughout subsequent developmental stages by small groups of endocrine cells forming islets. The islets are located within the cephalic part of the dorsal pancreas. At the end of the embryonic period, the pancreatic islet agglomerates branch off, and as a result of their remodeling, surround the splenic “bulb”. The stage of pancreatic endocrine ring formation is the first step in formation of intrasplenic islets characteristics for the adult specimens of the grass snake. The arrangement of endocrine cells within islets changes during pancreas differentiation. Initially, the core of islets formed from B and D cells is surrounded by a cluster of A cells. Subsequently, A, B, and D endocrine cells are mixed throughout the islets. Before grass snake hatching, A and B endocrine cells are intermingled within the islets, but D cells are arranged centrally. Moreover, the pancreatic polypeptide (PP) cells are not found within the embryonic pancreas of the grass snake. Variation in the proportions of different cell types, depending on the part of the pancreas, may affect the islet function—a higher proportion of glucagon cells is beneficial for insulin secretion.

scholarly journals Flow-independent accumulation of motor-competent non-muscle myosin II in the contractile ring is essential for cytokinesis

2018 ◽  
Author(s):  
DS Osorio ◽  
FY Chan ◽  
J Saramago ◽  
J Leite ◽  
AM Silva ◽  
...  
Keyword(s):  
Motor Activity ◽  
Myosin Ii ◽  
Minor Role ◽  
Cortical Actin ◽  
Animal Cells ◽  
Contractile Ring ◽  
Myosin Motor ◽  
C Elegans ◽  
Ring Assembly ◽  
Muscle Myosin

AbstractCytokinesis in animal cells requires the assembly of a contractile actomyosin ring, whose subsequent constriction physically separates the two daughter cells. Non-muscle myosin II (myosin) is essential for cytokinesis, but the role of its motor activity remains poorly defined. Here, we examine cytokinesis in C. elegans one-cell embryos expressing myosin motor mutants generated by genome editing. Motor-dead myosin, which is capable of binding F-actin, does not support cytokinesis, and embryos co-expressing motor-dead and wild-type myosin are delayed in cytokinesis. Partially motor-impaired myosin also delays cytokinesis and renders contractile rings more sensitive to reduced myosin levels. Thus, myosin motor activity, rather than its ability to cross-link actin filaments, drives contractile ring assembly and constriction. We further demonstrate that myosin motor activity is required for long-range cortical actin flows, but that flows per se play a minor role in contractile ring assembly. Our results suggest that flow-independent recruitment of motor-competent myosin to the cell equator is both essential and rate-limiting for cytokinesis.

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