scholarly journals Polytene chromosomes in mouse trophoblast giant cells

Development ◽  
1988 ◽  
Vol 102 (1) ◽  
pp. 127-134 ◽  
Author(s):  
S. Varmuza ◽  
V. Prideaux ◽  
R. Kothary ◽  
J. Rossant
Keyword(s):  
Dna Replication ◽  
Salivary Glands ◽  
Giant Cell ◽  
Polytene Chromosomes ◽  
Dna Amplification ◽  
Cell Types ◽  
Giant Cells ◽  
Cytological Evidence ◽  
Trophoblast Giant Cells

Mouse trophoblast giant cells undergo successive rounds of DNA replication resulting in amplification of the genome. It has been difficult to determine whether giant cell chromosomes are polyploid as in liver cells or polytene as in Dipteran salivary glands because the chromosomes do not condense. We have examined the pattern of hybridization of mouse giant cells with a variety of in situ chromosome markers to address this question. Hemizygous markers displayed one hybridization signal per nucleus in both diploid and giant cells, while homozygous markers displayed two signals per nucleus in both cell types. These patterns are consistent with cytological evidence indicating that giant cell chromosomes are polytene rather than polyploid. However, in contrast to the situation in Dipteran salivary glands, the two homologues do not appear to be closely associated. We conclude that the mechanism of giant cell DNA amplification involves multiple rounds of DNA replication in the absence of both karyokinesis and cytokinesis, and that sister chromatids, but not homologous chromosomes, remain closely associated during this process.

The mechanism of mouse egg-cylinder morphogenesis in vitro

Development ◽  
1981 ◽  
Vol 61 (1) ◽  
pp. 277-287
Author(s):  
A. J. Copp
Keyword(s):  
Giant Cell ◽  
Cell Formation ◽  
Cell Movement ◽  
Giant Cells ◽  
Cell Number ◽  
Dependent Change ◽  
Morphogenesis In Vitro ◽  
Trophoblast Giant Cells

The number of trophoblast giant cells in outgrowths of mouse blastocysts was determined before, during and after egg-cylinder formation in vitro. Giant-cell numbers rose initially but reached a plateau 12 h before the egg cylinder appeared. A secondary increase began 24 h after egg-cylinder formation. Blastocysts whose mural trophectoderm cells were removed before or shortly after attachment in vitro formed egg cylinders at the same time as intact blastocysts but their trophoblast outgrowths contained fewer giant cells at this time. The results support the idea that egg-cylinder formation in vitro is accompanied by a redirection of the polar to mural trophectoderm cell movement which characterizes blastocysts before implantation. The resumption of giant-cell number increase in trophoblast outgrowths after egg-cylinder formation may correspond to secondary giant-cell formation in vivo. It is suggested that a time-dependent change in the strength of trophoblast cell adhesion to the substratum occurs after blastocyst attachment in vitro which restricts the further entry of polar cells into the outgrowth and therefore results in egg-cylinder formation.

scholarly journals Giant Cell Urothelial Carcinoma of Bladder

2021 ◽  
Vol 2021 ◽  
pp. 1-5
Author(s):  
Harshima Disvini Wijesinghe ◽  
Ajith Malalasekera
Keyword(s):  
Urothelial Carcinoma ◽  
Giant Cell ◽  
Early Stage ◽  
Giant Cells ◽  
World Health ◽  
World Health Organization Classification ◽  
Health Organization

Giant cell urothelial carcinoma is a rare variant of bladder cancer recognized by the current World Health Organization classification of urologic tumours. It is an aggressive tumour with a poor prognosis that usually presents at an advanced stage. It is characterized histologically by pleomorphic giant cells. We discuss a case of giant cell urothelial carcinoma presenting at an early stage in a previously well 62-year-old woman. Histology showed a tumour comprising pancytokeratin positive bizarre mononuclear and multi-nuclear giant cells admixed with areas of conventional urothelial carcinoma and carcinoma in situ. Three-month follow-up cystoscopy and magnetic resonance imaging showed no evidence of recurrence or pelvic lymphadenopathy.

scholarly journals A molecular mechanism of mouse placental spongiotrophoblast differentiation regulated by prolyl oligopeptidase

Zygote ◽  
2019 ◽  
Vol 27 (1) ◽  
pp. 49-53
Author(s):  
Yuki Maruyama ◽  
Atsushi P. Kimura
Keyword(s):  
Molecular Mechanism ◽  
Critical Role ◽  
Specific Inhibitor ◽  
Cell Types ◽  
Giant Cells ◽  
Akt Pathway ◽  
Prolyl Oligopeptidase ◽  
Trophoblast Stem ◽  
Trophoblast Stem Cell ◽  
Trophoblast Giant Cells

SummaryIn eutherian mammals, the placenta plays a critical role in embryo development by supplying nutrients and hormones and mediating interaction with the mother. To establish the fine connection between mother and embryo, the placenta needs to be formed normally, but the mechanism of placental differentiation is not fully understood. We previously revealed that mouse prolyl oligopeptidase (POP) plays a role in trophoblast stem cell (TSC) differentiation into two placental cell types, spongiotrophoblasts (SpT) and trophoblast giant cells. Here, we focused on SpT differentiation and attempted to elucidate a molecular mechanism. ForAscl2,Arnt, andEgfrgenes that are indispensable for SpT formation, we found that a POP-specific inhibitor, SUAM-14746, significantly decreasedAscl2expression, which was consistent with a significant decrease in expression ofFlt1, a gene downstream ofAscl2. Although this downregulation was unlikely to be mediated by the PI3K-Akt pathway, our results indicated that POP controls TSC differentiation into SpT by regulating theAscl2gene.

scholarly journals H3K9 Promotes Under-Replication of Pericentromeric Heterochromatin in Drosophila Salivary Gland Polytene Chromosomes

Genes ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 93 ◽  
Author(s):  
Robin Armstrong ◽  
Taylor Penke ◽  
Samuel Chao ◽  
Gabrielle Gentile ◽  
Brian Strahl ◽  
...  
Keyword(s):  
Salivary Gland ◽  
Dna Replication ◽  
Polytene Chromosomes ◽  
Cell Types ◽  
Gene Replacement ◽  
Pericentric Heterochromatin ◽  
Replication Initiation ◽  
H3k9 Methylation ◽  
Diploid Cells ◽  
And Function

Chromatin structure and its organization contributes to the proper regulation and timing of DNA replication. Yet, the precise mechanism by which chromatin contributes to DNA replication remains incompletely understood. This is particularly true for cell types that rely on polyploidization as a developmental strategy for growth and high biosynthetic capacity. During Drosophila larval development, cells of the salivary gland undergo endoreplication, repetitive rounds of DNA synthesis without intervening cell division, resulting in ploidy values of ~1350C. S phase of these endocycles displays a reproducible pattern of early and late replicating regions of the genome resulting from the activity of the same replication initiation factors that are used in diploid cells. However, unlike diploid cells, the latest replicating regions of polyploid salivary gland genomes, composed primarily of pericentric heterochromatic enriched in H3K9 methylation, are not replicated each endocycle, resulting in under-replicated domains with reduced ploidy. Here, we employ a histone gene replacement strategy in Drosophila to demonstrate that mutation of a histone residue important for heterochromatin organization and function (H3K9) but not mutation of a histone residue important for euchromatin function (H4K16), disrupts proper endoreplication in Drosophila salivary gland polyploid genomes thereby leading to DNA copy gain in pericentric heterochromatin. These findings reveal that H3K9 is necessary for normal levels of under-replication of pericentric heterochromatin and suggest that under-replication at pericentric heterochromatin is mediated through H3K9 methylation.

scholarly journals Reciprocal expression of 17α-hydroxylase-C17,20-lyase and aromatase cytochrome P450 during bovine trophoblast differentiation: a two-cell system drives placental oestrogen synthesis

Reproduction ◽  
2006 ◽  
Vol 131 (4) ◽  
pp. 669-679 ◽  
Author(s):  
G Schuler ◽  
G R Özalp ◽  
B Hoffmann ◽  
N Harada ◽  
P Browne ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Cell Types ◽  
Staining Intensity ◽  
Giant Cells ◽  
Cell System ◽  
Cellular Level ◽  
Specific Staining ◽  
Cytoplasmic Staining ◽  
Distinct Cell ◽  
Trophoblast Giant Cells

No definitive information is yet available on the steroidogenic capacity of the two morphologically distinct cell types forming the bovine trophoblast, the uninucleated trophoblast cells (UTCs) and the trophoblast giant cells (TGCs). Hence, in order to localise 17α-hydroxylase-C17,20-lyase (P450c17) on a cellular level and to monitor its expression as a function of gestational age, placentomes from pregnant (days 80–284; n = 19), prepartal (days 273–282; 24–36 h prior to the onset of labour; n = 3) and parturient cows (n = 5) were immunostained for P450c17 using an antiserum against the recombinant bovine enzyme. At all stages investigated, P450c17 was exclusively found in the UTCs of chorionic villi (CV), where staining was ubiquitous between days 80 and 160, but was largely restricted to primary CV and the branching sites of secondary CV between days 160 and 240. Thereafter, a distinct ubiquitous staining reoccurred in the UTCs of all CV in late pregnant, prepartal and parturient animals. Using an antiserum against human aromatase cytochrome P450 (P450arom), specific cytoplasmic staining was observed in TGCs. In placentomes from pregnant cows, staining intensity was higher in mature compared with immature TGCs and was more pronounced in the trophoblast covering big stem villi compared with the trophoblast at other sites of the villous tree. In placentomes of a parturient cow, specific staining was only found in mature TGCs that survived the normal, but substantial, prepartal decline in TGC numbers. These results clearly showed that bovine UTCs and TGCs exhibit different steroidogenic capacities, constituting a ‘two-cell’ organisation for oestrogen synthesis. P450c17 expression appears to be quickly down-regulated and P450arom is up-regulated when UTCs enter the TGC differentiation pathway.

scholarly journals Periodic Expression of the Cyclin-dependent Kinase Inhibitor p57Kip2 in Trophoblast Giant Cells Defines a G2-like Gap Phase of the Endocycle

2000 ◽  
Vol 11 (3) ◽  
pp. 1037-1045 ◽  
Author(s):  
Naka Hattori ◽  
Tyler C. Davies ◽  
Lynn Anson-Cartwright ◽  
James C. Cross
Keyword(s):  
Dna Replication ◽  
Protein Targeting ◽  
Kinase Inhibitor ◽  
Phosphorylation Site ◽  
Giant Cells ◽  
S Phase ◽  
Stable Form ◽  
Cdk Inhibitor ◽  
Cyclin Dependent Kinase ◽  
Trophoblast Giant Cells

Endoreduplication is an unusual form of cell cycle in which rounds of DNA synthesis repeat in the absence of intervening mitoses. How G1/S cyclin-dependent kinase (Cdk) activity is regulated during the mammalian endocycle is poorly understood. We show here that expression of the G1/S Cdk inhibitor p57Kip2 is induced coincidentally with the transition to the endocycle in trophoblast giant cells.Kip2 mRNA is constitutively expressed during subsequent endocycles, but the protein level fluctuates. In trophoblast giant cells synchronized for the first few endocycles, the p57Kip2 protein accumulates only at the end of S-phase and then rapidly disappears a few hours before the onset of the next S-phase. The protein becomes stabilized by mutation of a C-terminal Cdk phosphorylation site. As a consequence, introduction of this stable form of p57Kip2 into giant cells blocks S-phase entry. These data imply that p57Kip2 is subject to phosphorylation-dependent turnover. Surprisingly, although this occurs in endoreduplicating giant cells, p57Kip2 is stable when ectopically expressed in proliferating trophoblast cells, indicating that these cells lack the mechanism for protein targeting and/or degradation. These data show that the appearance of p57Kip2punctuates the completion of DNA replication, whereas its turnover is subsequently required to initiate the next round of endoreduplication in trophoblast giant cells. Cyclical expression of a Cdk inhibitor, by terminating G1/S Cdk activity, may help promote the resetting of DNA replication machinery.

Identification of two new nonclassical members of the rat prolactin family

2000 ◽  
Vol 24 (1) ◽  
pp. 95-108 ◽  
Author(s):  
N Sahgal ◽  
GT Knipp ◽  
B Liu ◽  
BM Chapman ◽  
G Dai ◽  
...  
Keyword(s):  
Giant Cell ◽  
Cell Layer ◽  
Giant Cells ◽  
Trophoblast Giant Cell ◽  
Related Protein ◽  
Junctional Zone ◽  
Dbest Database ◽  
Chorioallantoic Placenta ◽  
Trophoblast Giant Cells ◽  
Ectoplacental Cone

The prolactin (PRL) family is comprised of a group of hormones/cytokines that are expressed in the anterior pituitary, uterus, and placenta. These proteins participate in the control of maternal and fetal adaptations to pregnancy. In this report, we have identified two new nonclassical members of the rat PRL family through a search of the National Center for Biotechnology Information dbEST database. The cDNAs were sequenced and their corresponding mRNAs characterized. Overall, the rat cDNAs showed considerable structural similarities with mouse proliferin-related protein (PLF-RP) and prolactin-like protein-F (PLP-F), consistent with their classification as rat homologs for PLF-RP and PLP-F. The expression of both cytokines/hormones was restricted to the placenta. The intraplacental sites of PLF-RP and PLP-F synthesis differed in the rat and the mouse. In the mouse, PLF-RP was expressed in the trophoblast giant cell layer of the midgestation chorioallantoic and choriovitelline placentas and, during later gestation, in the trophoblast giant cell and spongiotrophoblast layers within the junctional zone of the mouse chorioallantoic placenta. In contrast, in the rat, PLF-RP was first expressed in the primordium of the chorioallantoic placenta (ectoplacental cone region) and, later, exclusively within the labyrinth zone of the chorioallantoic placenta. In the mouse, PLP-F is an exclusive product of the spongiotrophoblast layer, whereas in the rat, trophoblast giant cells were found to be the major source of PLP-F, with a lesser contribution from spongiotrophoblast cells late in gestation. In summary, we have established the presence of PLF-RP and PLP-F in the rat.

scholarly journals Characterization of a novel large-field cone bipolar cell type in the primate retina: Evidence for selective cone connections

2010 ◽  
Vol 28 (1) ◽  
pp. 29-37 ◽  
Author(s):  
HANNAH R. JOO ◽  
BETH B. PETERSON ◽  
TONI J. HAUN ◽  
DENNIS M. DACEY
Keyword(s):  
Giant Cell ◽  
Bipolar Cell ◽  
Visual Information ◽  
Dendritic Tree ◽  
Cell Types ◽  
Giant Cells ◽  
Bipolar Cells ◽  
Large Field ◽  
Inner Plexiform Layer ◽  
Dendritic Field

AbstractParallel processing of visual information begins at the first synapse in the retina between the photoreceptors and bipolar cells. Ten bipolar cell types have been previously described in the primate retina: one rod and nine cone bipolar types. In this paper, we describe an 11th type of bipolar cell identified in Golgi-stained macaque retinal whole mount and vertical section. Axonal stratification depth, in addition to dendritic and axonal morphology, distinguished the “giant” cell from all previously well-recognized bipolar cell types. The giant bipolar cell had a very large and sparsely branched dendritic tree and a relatively large axonal arbor that costratified with the DB4 bipolar cell near the center of the inner plexiform layer. The sparseness of the giant bipolar’s dendritic arbor indicates that, like the blue cone bipolar, it does not contact all the cones in its dendritic field. Giant cells contacting the same cones as midget bipolar cells, which are known to contact single long-wavelength (L) or medium-wavelength (M) cones, demonstrate that the giant cell does not exclusively contact short-wavelength (S) cones and, therefore, is not a variant of the previously described blue cone bipolar. This conclusion is further supported by measurement of the cone contact spacing for the giant bipolar. The giant cell contacts an average of about half the cones in its dendritic field (mean ± s.d. = 52 ± 17.6%; n = 6), with a range of 27–82%. The dendrites from single or neighboring giant cells that converge onto the same cones suggest that the giant cell may selectively target a subset of cones with a highly variable local density, such as the L or M cones.

Activation of potential initiation sites of DNA replication and induction of new initiation within the same cycle by puromycin in Drosophila polytene chromosomes

1984 ◽  
Vol 65 (1) ◽  
pp. 95-109
Author(s):  
A.S. Mukherjee ◽  
C. Chatterjee
Keyword(s):  
Dna Replication ◽  
Salivary Glands ◽  
Polytene Chromosomes ◽  
Cell System ◽  
Replication Cycle ◽  
Physiological Conditions ◽  
Protein Factor ◽  
Drosophila Hydei ◽  
Alpha Amanitin ◽  
Potential Initiation

DNA replication in the polytene chromosomes of larval salivary glands of Drosophila hydei has been examined under normal physiological conditions, with or without puromycin, by an autoradiographic procedure using [3H]thymidine. It has been demonstrated that puromycin induces new labelling patterns that can be identified as initiation patterns. Such initiation patterns were found to have been induced during both the initial (interband labelling patterns) and the terminal (discontinuous) phases. Both induced patterns are sensitive to alpha-amanitin. These findings lead us to suggest that (a) the puff-interband-labelled patterns are indeed the initial patterns, and (b) the induction of new initiation, which is normally known to be prevented until the completion of the cycle, can be brought about by puromycin. The results also suggest the probable existence of a pool of protein factor(s) for the initiation of a replication cycle already present in the cell system.

scholarly journals Differentiation of Trophoblast Giant Cells and Their Metabolic Functions Are Dependent on Peroxisome Proliferator-Activated Receptor β/δ

2006 ◽  
Vol 26 (8) ◽  
pp. 3266-3281 ◽  
Author(s):  
Karim Nadra ◽  
Silvia I. Anghel ◽  
Elisabeth Joye ◽  
Nguan Soon Tan ◽  
Sharmila Basu-Modak ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Giant Cell ◽  
Giant Cells ◽  
Peroxisome Proliferator ◽  
Phosphatidylinositol 3 Kinase ◽  
Peroxisome Proliferator Activated Receptor ◽  
Metabolic Functions ◽  
Integrin Linked Kinase ◽  
Trophoblast Giant Cells

ABSTRACT Mutation of the nuclear receptor peroxisome proliferator-activated receptor β/δ (PPARβ/δ) severely affects placenta development, leading to embryonic death at embryonic day 9.5 (E9.5) to E10.5 of most, but not all, PPARβ/δ-null mutant embryos. While very little is known at present about the pathway governed by PPARβ/δ in the developing placenta, this paper demonstrates that the main alteration of the placenta of PPARβ/δ-null embryos is found in the giant cell layer. PPARβ/δ activity is in fact essential for the differentiation of the Rcho-1 cells in giant cells, as shown by the severe inhibition of differentiation once PPARβ/δ is silenced. Conversely, exposure of Rcho-1 cells to a PPARβ/δ agonist triggers a massive differentiation via increased expression of 3-phosphoinositide-dependent kinase 1 and integrin-linked kinase and subsequent phosphorylation of Akt. The links between PPARβ/δ activity in giant cells and its role on Akt activity are further strengthened by the remarkable pattern of phospho-Akt expression in vivo at E9.5, specifically in the nucleus of the giant cells. In addition to this phosphatidylinositol 3-kinase/Akt main pathway, PPARβ/δ also induced giant cell differentiation via increased expression of I-mfa, an inhibitor of Mash-2 activity. Finally, giant cell differentiation at E9.5 is accompanied by a PPARβ/δ-dependent accumulation of lipid droplets and an increased expression of the adipose differentiation-related protein (also called adipophilin), which may participate to lipid metabolism and/or steroidogenesis. Altogether, this important role of PPARβ/δ in placenta development and giant cell differentiation should be considered when contemplating the potency of PPARβ/δ agonist as therapeutic agents of broad application.

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