asymmetric cell division
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Asymmetric distribution of fate determinants within cells is an essential biological strategy to prepare them for asymmetric division. In this work we measure the intracellular distribution of 12 maternal microRNAs (miRNA) along the animal-vegetal axis of the Xenopus laevis oocyte using qPCR tomography. We find the miRNAs have distinct intracellular profiles that resemble two out of the three profiles we previously observed for mRNAs. Our results suggest that miRNAs in addition to proteins and mRNAs may have asymmetric distribution within the oocyte and may contribute to asymmetric cell division as cell fate determinants.
- MeSH
- buněčné dělení genetika MeSH
- mikro RNA genetika MeSH
- oocyty metabolismus MeSH
- Xenopus laevis MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Asymmetric division is a property of eukaryotic cells that is fundamental to the formation of higher life forms. Despite its importance, the mechanism behind it remains elusive. Asymmetry in the cell is induced by polarization of cell fate determinants that become unevenly distributed among progeny cells. So far dozens of determinants have been identified. Xenopus laevis is an ideal system to study asymmetric cell division during early development, because of the huge size of its oocytes and early-stage blastomeres. Here, we present the current knowledge about localization and distribution of cell fate determinants along the three body axes: animal-vegetal, dorsal-ventral, and left-right. Uneven distribution of cell fate determinants during early development specifies the formation of the embryonic body plan.
UNLABELLED: How bacteria control proper septum placement at midcell, to guarantee the generation of identical daughter cells, is still largely unknown. Although different systems involved in the selection of the division site have been described in selected species, these do not appear to be widely conserved. Here, we report that LocZ (Spr0334), a newly identified cell division protein, is involved in proper septum placement in Streptococcus pneumoniae. We show that locZ is not essential but that its deletion results in cell division defects and shape deformation, causing cells to divide asymmetrically and generate unequally sized, occasionally anucleated, daughter cells. LocZ has a unique localization profile. It arrives early at midcell, before FtsZ and FtsA, and leaves the septum early, apparently moving along with the equatorial rings that mark the future division sites. Consistently, cells lacking LocZ also show misplacement of the Z-ring, suggesting that it could act as a positive regulator to determine septum placement. LocZ was identified as a substrate of the Ser/Thr protein kinase StkP, which regulates cell division in S. pneumoniae. Interestingly, homologues of LocZ are found only in streptococci, lactococci, and enterococci, indicating that this close phylogenetically related group of bacteria evolved a specific solution to spatially regulate cell division. IMPORTANCE: Bacterial cell division is a highly ordered process regulated in time and space. Recently, we reported that the Ser/Thr protein kinase StkP regulates cell division in Streptococcus pneumoniae, through phosphorylation of several key proteins. Here, we characterized one of the StkP substrates, Spr0334, which we named LocZ. We show that LocZ is a new cell division protein important for proper septum placement and likely functions as a marker of the cell division site. Consistently, LocZ supports proper Z-ring positioning at midcell. LocZ is conserved only among streptococci, lactococci, and enterococci, which lack homologues of the Min and nucleoid occlusion effectors, indicating that these bacteria adapted a unique mechanism to find their middle, reflecting their specific shape and symmetry.
- MeSH
- buněčné dělení * MeSH
- delece genu MeSH
- Enterococcus genetika MeSH
- Lactococcus genetika MeSH
- proteiny buněčného cyklu genetika metabolismus MeSH
- sekvenční homologie aminokyselin MeSH
- Streptococcus pneumoniae cytologie genetika fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Differentiation of Trypanosoma brucei, a flagellated protozoan parasite, between life cycle stages typically occurs through an asymmetric cell division process, producing two morphologically distinct daughter cells. Conversely, proliferative cell divisions produce two daughter cells, which look similar but are not identical. To examine in detail differences between the daughter cells of a proliferative division of procyclic T. brucei we used the recently identified constituents of the flagella connector. These segregate asymmetrically during cytokinesis allowing the new-flagellum and the old-flagellum daughters to be distinguished. We discovered that there are distinct morphological differences between the two daughters, with the new-flagellum daughter in particular re-modelling rapidly and extensively in early G1. This re-modelling process involves an increase in cell body, flagellum and flagellum attachment zone length and is accompanied by architectural changes to the anterior cell end. The old-flagellum daughter undergoes a different G1 re-modelling, however, despite this there was no difference in G1 duration of their respective cell cycles. This work demonstrates that the two daughters of a proliferative division of T. brucei are non-equivalent and enables more refined morphological analysis of mutant phenotypes. We suggest all proliferative divisions in T. brucei and related organisms will involve non-equivalence.
- MeSH
- buněčné dělení MeSH
- cytokineze MeSH
- flagella genetika metabolismus MeSH
- proliferace buněk MeSH
- protozoální proteiny genetika metabolismus MeSH
- stadia vývoje MeSH
- Trypanosoma brucei brucei cytologie genetika růst a vývoj metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
During sporulation, Bacillus subtilis forms an asymmetric septum, dividing the cell into two compartments, a mother cell and a forespore. The site of asymmetric septation is linked to the membrane where FtsZ and SpoIIE initiate the formation of the Z-ring and the E-ring, respectively. These rings then serve as a scaffold for the other cell division and peptidoglycan synthesizing proteins needed to build the septum. However, despite decades of research, not enough is known about how the asymmetric septation site is determined. Here, we identified and characterized the interaction between SpoIIE and RefZ. We show that these two proteins transiently colocalize during the early stages of asymmetric septum formation when RefZ localizes primarily from the mother cell side of the septum. We propose that these proteins and their interplay with the spatial organization of the chromosome play a role in controlling asymmetric septum positioning.
- MeSH
- chondrocyty fyziologie patologie MeSH
- kloubní chrupavka fyziologie patofyziologie MeSH
- osteoartróza patofyziologie MeSH
- Publikační typ
- kongresy MeSH
... Cell Growth and Division -- 12. Cell-Cell Adhesion and the Extracellular Matrix -- 13. ... ... -- Summary -- References -- CHAPTER ^ -- Cell Growth, and Division -- The Control of Cell Division -- ... ... -- Determination of Cell-Cycle Times A Special “Trigger Protein” May Control Cell Division Cell Division ... ... Will Stop Dividing When They Run Out of Space Positional Signals Also Control Cell Division Cancer Cells ... ... Shortened When Not Limited by the Rates of Biosynthesis -- Summary -- Cell Division -- Cell Division ...
xxxix, 1146 s. : il., tab. ; 28 cm
- MeSH
- biologie buňky MeSH
- molekulární biologie MeSH
- Publikační typ
- monografie MeSH
- Konspekt
- Biochemie. Molekulární biologie. Biofyzika
- NLK Obory
- biologie
- cytologie, klinická cytologie
Hematopoietic stem and progenitor cells (HSPCs) are crucial for lifelong blood cell production. We analyzed the cell cycle and cell production rate in HSPCs in murine hematopoiesis. The labeling of DNA-synthesizing cells by two thymidine analogues, optimized for in-vivo use, enabled determination of the cell cycle flow rate into G2-phase, the duration of S-phase and the average cell cycle time in Sca-1+ and Sca-1- HSPCs. Determination of cells with 2n DNA content labeled in preceding S-phase was then used to establish the cell flow rates in G1-phase. Our measurements revealed a significant difference in how Sca-1+ and Sca-1- myeloid progenitors self-renew and differentiate. Division of the Sca-1+ progenitors led to loss of the Sca-1 marker in about half of newly produced cells, corresponding to asymmetric cell division. Sca-1- cells arising from cell division entered a new round of the cell cycle, corresponding to symmetric self-renewing cell division. The novel data also enabled the estimation of the cell production rates in Sca-1+ and in three subtypes of Sca-1- HSPCs and revealed Sca-1 negative cells as the major amplification stage in the blood cell development.
- MeSH
- antigeny Ly metabolismus MeSH
- buněčná diferenciace * MeSH
- buněčná sebeobnova MeSH
- buněčný cyklus * MeSH
- DNA biosyntéza MeSH
- G2 fáze MeSH
- hematopoetické kmenové buňky cytologie metabolismus MeSH
- membránové proteiny metabolismus MeSH
- myši inbrední C57BL MeSH
- počet buněk MeSH
- proliferace buněk MeSH
- reologie MeSH
- S fáze MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
... Division 12 -- Mutations May Be Good, Bad, or Indifferent 13 -- The Work of Cells 14 -- Cells Build ... ... -- Primary Cell Cultures Can Be Used to Study Cell Differentiation 396 -- Primary Cell Cultures and Cell ... ... Migration 797 -- 19 INTEGRATING CELLS INTO -- TISSUES 801 -- 19.1 -- Cell-Cell and Cell-Matrix Adhesion ... ... Cell Division -- 930 -- Yeast Mating-???? ... ... Switching Depends upon -- Asymmetric Cell Division 930 -- CONTENTS • XXXÜ! ...
6th ed. xxxvii, 1150 s. : il., tab. ; 29 cm
- MeSH
- biologie buňky MeSH
- molekulární biologie MeSH
- Publikační typ
- monografie MeSH
- Konspekt
- Biochemie. Molekulární biologie. Biofyzika
- NLK Obory
- biologie
- cytologie, klinická cytologie
