scholarly journals Cytoplasmic forces functionally reorganize nuclear condensates in oocytes

2021 ◽  
Author(s):  
Adel Al Jord ◽  
Gaëlle Letort ◽  
Adrien Eichmuller ◽  
Soline Chanet ◽  
Jean-René Huynh ◽  
...  
Keyword(s):  
Germ Cells ◽  
Viral Infections ◽  
Mrna Processing ◽  
Cajal Bodies ◽  
Random Forces ◽  
Splicing Speckles ◽  
Membrane Bound ◽  
Cytoskeletal Motors ◽  
Different Sources

AbstractCells remodel their cytoplasm with force-generating cytoskeletal motors1. Their activity generates random forces that stir the cytoplasm, agitating and displacing membrane-bound organelles like the nucleus in somatic2–4 and germ5–7 cells. These forces are transmitted inside the nucleus4,7, yet their consequences on liquid-like biomolecular condensates8–10 residing in the nucleus remain unexplored. Here, we probe experimentally and computationally diverse nuclear condensates, that include splicing speckles, Cajal bodies, and nucleoli, during cytoplasmic remodeling of female germ cells named oocytes. We discover that growing mammalian oocytes deploy cytoplasmic forces to timely impose multiscale reorganization of condensates inside the nucleus. We determine that cytoplasmic forces accelerate nuclear condensate collision-coalescence and molecular kinetics within condensates. Inversely, disrupting the forces decelerates nuclear condensate reorganization on both scales. We link the molecular deceleration found in mRNA-processing splicing speckles to reduced and altered splicing of mRNA, which in oocytes impedes fertility11. We establish that different sources of cytoplasmic forces can reorganize nuclear condensates and that this cytoplasmic aptitude for subnuclear reorganization is evolutionary conserved in insects. Our work implies that cells evolved a mechanism, based on cytoplasmic force tuning, to functionally regulate a broad range of nuclear condensates across scales. This finding opens new perspectives when studying condensate-associated pathologies like cancer, neurodegeneration and viral infections12.One sentence summaryCytoplasmic random forces in growing oocytes drive multiscale reorganization of nuclear liquid-like biomolecular condensates.

The growth of the pollen tube wall in Oenothera organensis

1975 ◽  
Vol 18 (3) ◽  
pp. 519-532
Author(s):  
H.G. Dickinson ◽  
J. Lawson
Keyword(s):  
Pollen Tube ◽  
Tube Wall ◽  
Wall Material ◽  
Fibrillar Material ◽  
Stage Of Development ◽  
Large Numbers ◽  
Membrane Bound ◽  
Pollen Tube Wall ◽  
Different Sources ◽  
Dictyosome Vesicles

The growth of the pollen tube wall of Oenothera is effected by the expulsion of fibrillar material from the cytoplasm into the developing wall. This material may also be seen in the cytoplasm, contained in membrane-bound vesicles. It is not clear how the content of the vesicles is discharged, but it appears not to involve the participation of microtubules. The source of the cytoplasmic fibrillar bodies depends upon the stage of development of the pollen tube. The earilest growth is derived from the inclusion into the wall of vesicles containing pre-formed materials present in the grain on pollination. During the next stage of growth the wall is derived from the content of double-membraned inclusions also present in the pollen. The content of the former vesicles is not so similar to the wall as the latter, but intermediates between the 2 types of vesicle may be seen in the cytoplasm, indicating that the former are formed from the latter. Most of the tube wall is derived from the products of dictyosomes in the pollen grain or tube. These dicytosomes are few in number and they must be exceedingly active. This, and the observation that dictyosome vesicles are frequently associated with banked complexes of mitochondria, indicates that some steps in the metabolism of the vesicular content, perhaps phosphorylation, take place distant from the dicytosomes. These different sources of fibrillar material presumably permit the rapid starting of tube growth, without any attendant metabolism. However, it would be impossible to include enough pre-formed wall material in the grain to enable the full growth of the tube, so once started, it seems that the tube then relies on the elaboration of simple reserves for the contruction of its wall. These reserves are likely to be held in the pollen, and may be the large numbers of starch grains characteristic of the pollen cytoplasm.

Primary culture of porcine PGCs requires LIF and porcine membrane-bound stem cell factor

Zygote ◽  
1998 ◽  
Vol 6 (3) ◽  
pp. 271-275 ◽  
Author(s):  
Gabriela Durcova-Hills ◽  
Katja Prelle ◽  
Sigrid Müller ◽  
Miodrag Stojkovic ◽  
Jan Motlik ◽  
...  
Keyword(s):  
Stem Cell ◽  
Primary Culture ◽  
Germ Cells ◽  
Stem Cell Factor ◽  
Primordial Germ Cells ◽  
Embryonic Stem ◽  
Leukaemia Inhibitory Factor ◽  
Feeder Cells ◽  
Membrane Bound

We studied the effect of murine leukaemia inhibitory factor (LIF), human basic fibroblast growth factor (bFGF) and porcine stem cell factor (SCF) on the survival and/or proliferation of porcine primordial germ cells (PGCs) obtained from 27-day-old embryos in vitro. PGCs were cultured in embryonic stem cell (ESC) medium supplemented with or without either LIF (1000 IU/ml) alone or LIF together with bFGF (10 ng/ml). They were seeded on mitotically inactivated feeder cells, either STO or transfected STO cells (STO#8), expressing the membrane-bound form of porcine SCF. PGCs were identified by their alkaline phosphatase (AP) activity and counted after 1, 3 and 5 days in culture. After 1 day of culture, PGCs cultured on STO#8 cells showed significantly higher survival than PGCs cultured on STO cells (p < 0.05). The combined effect of SCF and LIF caused a significant increase in PGC number by day 3 of culture when PGCs were cultured on either STO cells (p < 0.01) or STO#8 (p < 0.001). When SCF and LIF were used together with bFGF no increase in the PGC number was observed. Our results suggest that the membrane-bound form of porcine SCF plays a pivotal role in the primary culture of porcine PGCs and that bFGF is not required in vitro.

scholarly journals TACE/ADAM17 is involved in germ cell apoptosis during rat spermatogenesis

Reproduction ◽  
2010 ◽  
Vol 140 (2) ◽  
pp. 305-317 ◽  
Author(s):  
Carlos Lizama ◽  
Diego Rojas-Benítez ◽  
Marcelo Antonelli ◽  
Andreas Ludwig ◽  
Ximena Bustamante-Marín ◽  
...  
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Cell Apoptosis ◽  
Ex Vivo ◽  
Extracellular Domain ◽  
Germ Cell Apoptosis ◽  
Protein Levels ◽  
Kit Receptor ◽  
Membrane Bound

The pathways leading to male germ cell apoptosisin vivoare poorly understood, but are highly relevant for the comprehension of sperm production regulation by the testis. In this work, we show the evidence of a mechanism where germ cell apoptosis is induced through the inactivation and shedding of the extracellular domain of KIT (c-kit) by the protease TACE/a disintegrin and metalloprotease 17 (ADAM17) during the first wave of spermatogenesis in the rat. We show that germ cells undergoing apoptosis lacked the extracellular domain of the KIT receptor. TACE/ADAM17, a membrane-bound metalloprotease, was highly expressed in germ cells undergoing apoptosis as well. On the contrary, cell surface presence of ADAM10, a closely related metalloprotease isoform, was not associated with apoptotic germ cells. Pharmacological inhibition of TACE/ADAM17, but not ADAM10, significantly prevented germ cell apoptosis in the male pubertal rat. Induction of TACE/ADAM17 by the phorbol-ester phorbol 12-myristate 13-acetate (PMA) induced germ cell apoptosis, which was prevented when an inhibitor of TACE/ADAM17 was present in the assay.Ex-vivorat testis culture showed that PMA induced the cleavage of the KIT extracellular domain. Isolation of apoptotic germ cells showed that even though protein levels of TACE/ADAM17 were higher in apoptotic germ cells than in nonapoptotic cells, the contrary was observed for ADAM10. These results suggest that TACE/ADAM17 is one of the elements triggering physiological germ cell apoptosis during the first wave of spermatogenesis.

scholarly journals The role of TREX in gene expression and disease

2016 ◽  
Vol 473 (19) ◽  
pp. 2911-2935 ◽  
Author(s):  
Catherine G. Heath ◽  
Nicolas Viphakone ◽  
Stuart A. Wilson
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Molecular Basis ◽  
Cellular Differentiation ◽  
Viral Infections ◽  
Vital Role ◽  
Mrna Processing ◽  
Cellular Functions ◽  
Lateral Sclerosis

TRanscription and EXport (TREX) is a conserved multisubunit complex essential for embryogenesis, organogenesis and cellular differentiation throughout life. By linking transcription, mRNA processing and export together, it exerts a physiologically vital role in the gene expression pathway. In addition, this complex prevents DNA damage and regulates the cell cycle by ensuring optimal gene expression. As the extent of TREX activity in viral infections, amyotrophic lateral sclerosis and cancer emerges, the need for a greater understanding of TREX function becomes evident. A complete elucidation of the composition, function and interactions of the complex will provide the framework for understanding the molecular basis for a variety of diseases. This review details the known composition of TREX, how it is regulated and its cellular functions with an emphasis on mammalian systems.

scholarly journals Human Reproduction is Regulated by Retrotransposons derived from Ancient Hominin-Specific Viral Infections

2020 ◽  
Author(s):  
Yu Tao ◽  
Xiinyu Xiang ◽  
Fei-Man Hsu ◽  
Julien Pontis ◽  
Didier Trono ◽  
...  
Keyword(s):  
Germ Cells ◽  
Viral Infections ◽  
Primordial Germ Cells ◽  
Embryonic Stem ◽  
Chromatin Accessibility ◽  
Dna Demethylation ◽  
Human Reproduction ◽  
Epigenetic Landscape

Abstract Germ cells are essential to pass DNA from one generation to the next. In human reproduction, germ cell development begins with the specification of primordial germ cells (PGCs) and a failure to specify PGCs leads to human infertility. Recent studies have revealed that the transcription factor network required for PGC specification has diverged in mammals, and this has a significant impact on our understanding of human reproduction. Here, we evaluated the emerging epigenetic landscape during hPGC specification using a combination of in vivo and in vitro analysis of hPGCs/hPGC-like cells (hPGCLCs) and human embryonic stem cells (hESCs). Our data reveals that hominid restricted Transposable Elements (TEs) partly derived from ancient viruses are pre-bound by the transcription factors TFAP2C and NANOG in undifferentiated hESCs, become transcriptionally induced during PGC specification and undergo dynamic epigenetic reprogramming leading to increased chromatin accessibility, localized DNA demethylation and establishment of broad peaks of H3K27ac. Using KRAB mediated CRISPRi we show that blocking this remodeling has a significant impact on hPGC specification. In summary, our data reveals that human reproduction requires the establishment of an epigenetic landscape during hPGC specification driven by the acquisition of hominid-specific TEs that were derived from ancient viral infections that entered the hominid germline less than 5 million years ago.

scholarly journals Similarities between bovine and human germline development revealed by single-cell RNAseq

Reproduction ◽  
2020 ◽  
Author(s):  
Delia Alba Soto ◽  
Pablo Juan Ross
Keyword(s):  
Single Cell ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Cell Lineage ◽  
Gonadal Development ◽  
Bmp Signaling ◽  
Molecular Characteristics ◽  
Germline Development ◽  
Membrane Bound ◽  
Fetal Ovary

The germ cell lineage ensures the creation of new individuals and perpetuates the genetic information across generations. Primordial germ cells are pioneers of gametes and exist transiently during development until they differentiate into oogonia in females, or spermatogonia in males. Little is known about the molecular characteristics of primordial germ cells in cattle. By performing single-cell RNA-sequencing, quantitative real-time PCR, and immunofluorescence analyses of fetal gonads between 40 and 90 days of fetal age, we evaluated the molecular signatures of bovine germ cells at the initial stages of gonadal development. Our results indicate that at 50 days of fetal age, bovine primordial germ cells were in the early stages of development, expressing genes of early primordial germ cells, including transcriptional regulators of human germline specification (e.g. SOX17, TFAP2C, and PRDM1). Bovine and human primordial germ cells also share expression of KIT, EPCAM, ITGA6, and PDPN genes coding for membrane-bound proteins, and an asynchronous pattern of differentiation. Additionally, the expression of members of Notch, Nodal/Activin, and BMP signaling cascades in the bovine fetal ovary, suggests that these pathways are involved in the interaction between germ cells and their niche. Results of this study provide insights into the mechanisms involved in the development of bovine primordial germ cells and put in evidence similarities between the bovine and human germline.

The Fine Structure of Oogonia and Oocytes in Human Ovaries

1967 ◽  
Vol 2 (2) ◽  
pp. 213-224
Author(s):  
T. G. BAKER ◽  
L. L. FRANCHI
Keyword(s):  
Fine Structure ◽  
Germ Cells ◽  
Post Partum ◽  
Normal Cells ◽  
Chromosomal Structure ◽  
Membrane Bound ◽  
Rat Ovary ◽  
Human Ovaries ◽  
Normal Differentiation ◽  
Irregular Mass

Twenty-eight foetal and post-natal human ovaries (6 weeks post conception to 11 years post partum) have been examined with the electron microscope. Stages in the normal differentiation of germ cells (oogonia; oocytes at the pre-leptotene, leptotene, zygotene, pachytene, and diplotene stages of meiotic prophase) were identified by comparison with (a) corresponding cells in histological and squash preparations, and (b) similar cells in the rat ovary. Atretic cells (oogonia in mitosis; oocytes at pachytene and diplotene) were also examined. The nuclei of oogonia contain an evenly dispersed fibrillar matrix which becomes organized into irregular strands in oocytes at pre-leptotene. At leptotene these strands become the sheaths surrounding unpaired, electron-dense axial threads or ‘cores’, which become associated in pairs during the transitory zygotene stage, and tend to be polarized within the nucleus. Single and paired threads are replaced by ‘tripartite ribbons’ (synaptinemal complexes) at pachytene; longitudinal subdivision of the lateral components of the ribbon is observed in some nuclei and may represent a later stage. At diplotene, essentially unpaired cores are observed as at leptotene, although they are thicker and more intimately related to the surrounding fibrillar sheath. The latter is also more highly organized than at earlier stages. This chromosomal structure is retained in oocytes in promordial follicles in post-natal ovaries. The dictyate stage observed in rat ovaries is not found in man. The organization of the cytoplasm does not change markedly as oogenesis advances, although organelles become more numerous, and the internal structure more complex, as the cells enlarge towards the diplotene stage. Oogonia degenerating during mitosis differ from normal cells in that the chromosomes become fused to form an irregular mass. Abnormal membrane-bound areas are also observed in the cytoplasm. Atretic oocytes at pachytene coalesce to form ‘pools’ of cytoplasm containing several nuclei in various stages of pyknosis. Atretic cells at diplotene may contain grossly swollen cytoplasmic organelles and clumped, homogeneous chromosomes. The ‘atretic divisions’ appear to be phagocytosed by somatic cells, but the means of elimination of degenerating meiocytes was not determined.

scholarly journals A testis-specific regulator of complex and hybrid N-glycan synthesis

2010 ◽  
Vol 190 (5) ◽  
pp. 893-910 ◽  
Author(s):  
Hung-Hsiang Huang ◽  
Pamela Stanley
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Sertoli Cells ◽  
Cho Cells ◽  
Cell Attachment ◽  
The Novel ◽  
Inhibitory Protein ◽  
Membrane Bound ◽  
Intermediate Compartment ◽  
High Mannose

Database analyses identified 4933434I20Rik as a glycosyltransferase-like gene expressed mainly in testicular germ cells and regulated during spermatogenesis. Expression of a membrane-bound form of the protein resulted in a marked and specific reduction in N-acetylglucosaminyltransferase I (GlcNAcT-I) activity and complex and hybrid N-glycan synthesis. Thus, the novel activity was termed GlcNAcT-I inhibitory protein (GnT1IP). Membrane-bound GnT1IP localizes to the ER, the ER-Golgi intermediate compartment (ERGIC), and the cis-Golgi. Coexpression of membrane-anchored GnT1IP with GlcNAcT-I causes association of the two proteins, inactivation of GlcNAcT-I, and mislocalization of GlcNAcT-I from the medial-Golgi to earlier compartments. Therefore, GnT1IP is a regulator of GlcNAcT-I and complex and hybrid N-glycan production. Importantly, the formation of high mannose N-glycans resulting from inhibition of GlcNAcT-I by GnT1IP markedly increases the adhesion of CHO cells to TM4 Sertoli cells. Testicular germ cells might use GnT1IP to induce the expression of high mannose N-glycans on glycoproteins, thereby facilitating Sertoli–germ cell attachment at a particular stage of spermatogenesis.

Structure and development of the spermatozoon of the parasitic nematode, Nematospiroides dubius

Parasitology ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 179-192 ◽  
Author(s):  
E. J. Wright ◽  
R. I. Sommerville
Keyword(s):  
Electron Microscopy ◽  
Germ Cells ◽  
Parasitic Nematode ◽  
Head Shape ◽  
Profound Change ◽  
Arrow Head ◽  
Golgi Bodies ◽  
Membrane Bound ◽  
Nematospiroides Dubius

Spermatogenesis and sperm maturation in Nematospiroides dubius were studied using electron microscopy. The testis is telegonic and germ cells in the zones of mitosis, growth and meiosis are connected by a central anucleate mass of cytoplasm, the rachis. The early part of spermatogenesis is dominated by the synthesis and growth of membrane-bound vesicles called membranous organelles, which originate from RER-associated Golgi bodies. Following meiosis the spermatids separate from the rachis and their chroinatin, which is no longer bounded by a nuclear envelope, condenses into an arrow-head shape and is extruded to form a tail-like structure. After insemination spermatozoa undergo a profound change called activation. The cytoplasmic region which was previously long and cylindrical becomes spherical and the membranous organelles which lined its perimeter fuse with the plasma membrane and become confined to the posterior hemisphere of the sperm, close to the nuclear tail. The anterior half of the sperm is devoid of organelles but contains many filaments organized into clumps and chains; this region being responsible for amoeboid locomotion of the sperm.

scholarly journals On the role of bacterial metalloproteases in COVID-19 associated cytokine storm

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
László Földvári-Nagy ◽  
Tamás Schnabel ◽  
Gabriella Dörnyei ◽  
Tamás Korcsmáros ◽  
Katalin Lenti
Keyword(s):  
Mortality Rate ◽  
Interleukin 6 ◽  
Viral Infections ◽  
Inflammatory Responses ◽  
Membrane Receptors ◽  
Critical Element ◽  
Cytokine Storm ◽  
Interleukin 6 Receptor ◽  
Membrane Bound ◽  
Prophylactic Use

AbstractThe cytokine release syndrome or cytokine storm, which is the hyper-induction of inflammatory responses has a central role in the mortality rate of COVID-19 and some other viral infections. Interleukin-6 (IL-6) is a key player in the development of cytokine storms. Shedding of interleukin-6 receptor (IL-6Rα) results in the accumulation of soluble interleukin-6 receptors (sIL-6R). Only relatively few cells express membrane-bound IL-6Rα. However, sIL-6R can act on potentially all cells and organs through the ubiquitously expressed gp130, the coreceptor of IL-6Rα. Through this, so-called trans-signaling, IL-6–sIL-6R is a powerful factor in the development of cytokine storms and multiorgan involvement. Some bacteria (e.g., Serratia marcescens, Staphylococcus aureus, Pseudomonas aeruginosa, Listeria monocytogenes), commonly considered to cause co-infections during viral pneumonia, can directly induce the shedding of membrane receptors, including IL-6Rα, or enhance endogenous shedding mechanisms causing the increase of sIL-6R level. Here we hypothesise that bacteria promoting shedding and increase the sIL-6R level can be an important contributing factor for the development of cytokine storms. Therefore, inhibition of IL-6Rα shedding by drastically reducing the number of relevant bacteria may be a critical element in reducing the chance of a cytokine storm. Validation of this hypothesis can support the consideration of the prophylactic use of antibiotics more widely and at an earlier stage of infection to decrease the mortality rate of COVID-19.

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