scholarly journals RYK-mediated filopodial pathfinding facilitates midgut elongation

Development ◽  
2020 ◽  
Vol 147 (20) ◽  
pp. dev195388
Author(s):  
Sha Wang ◽  
James P. Roy ◽  
Abigail J. Tomlinson ◽  
Ellen B. Wang ◽  
Yu-Hwai Tsai ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Navigation System ◽  
De Novo ◽  
Basal Surface ◽  
Daughter Cells ◽  
Guidance Cue ◽  
Epithelial Tube ◽  
Pseudostratified Epithelium ◽  
Rapid Elongation ◽  
Active Proliferation

ABSTRACTBetween embryonic days 10.5 and 14.5, active proliferation drives rapid elongation of the murine midgut epithelial tube. Within this pseudostratified epithelium, nuclei synthesize DNA near the basal surface and move apically to divide. After mitosis, the majority of daughter cells extend a long, basally oriented filopodial protrusion, building a de novo path along which their nuclei can return to the basal side. WNT5A, which is secreted by surrounding mesenchymal cells, acts as a guidance cue to orchestrate this epithelial pathfinding behavior, but how this signal is received by epithelial cells is unknown. Here, we have investigated two known WNT5A receptors: ROR2 and RYK. We found that epithelial ROR2 is dispensable for midgut elongation. However, loss of Ryk phenocopies the Wnt5a−/− phenotype, perturbing post-mitotic pathfinding and leading to apoptosis. These studies reveal that the ligand-receptor pair WNT5A-RYK acts as a navigation system to instruct filopodial pathfinding, a process that is crucial for continuous cell cycling to fuel rapid midgut elongation.

Electron Microscopic Study of the Epithelium of the Seminal Vesicle of Aging Rats

1974 ◽  
Vol 32 ◽  
pp. 138-139
Author(s):  
V. F. Allison ◽  
G. C. Fink ◽  
G. W. Cearley
Keyword(s):  
Cell Growth ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Seminal Vesicle ◽  
Seminal Vesicles ◽  
Epithelial Layer ◽  
Epithelial Hyperplasia ◽  
Electron Microscopic ◽  
Aging Rats ◽  
Pseudostratified Epithelium

It is well known that epithelial hyperplasia (benign hypertrophy) is common in the aging prostate of dogs and man. In contrast, little evidence is available for abnormal epithelial cell growth in seminal vesicles of aging animals. Recently, enlarged seminal vesicles were reported in senescent mice, however, that enlargement resulted from increased storage of secretion in the lumen and occurred concomitant to epithelial hypoplasia in that species.The present study is concerned with electron microscopic observations of changes occurring in the pseudostratified epithelium of the seminal vescles of aging rats. Special attention is given to certain non-epithelial cells which have entered the epithelial layer.

Three-dimensional organization and functional relationships of endocytotic compartments in pig intestinal epithelial cells

1992 ◽  
Vol 50 (1) ◽  
pp. 576-577
Author(s):  
Julian P. Heath ◽  
Buford L. Nichols ◽  
László G. Kömüves
Keyword(s):  
Electron Microscopy ◽  
Epithelial Cells ◽  
Intestinal Epithelial Cells ◽  
Three Dimensional ◽  
Intestinal Epithelial ◽  
Cell Surfaces ◽  
Basal Surface ◽  
Functional Relationships

The newborn pig intestine is adapted for the rapid and efficient absorption of nutrients from colostrum. In enterocytes, colostral proteins are taken up into an apical endocytotic complex of channels that transports them to target organelles or to the basal surface for release into the circulation. The apical endocytotic complex of tubules and vesicles clearly is a major intersection in the routes taken by vesicles trafficking to and from the Golgi, lysosomes, and the apical and basolateral cell surfaces.Jejunal tissues were taken from piglets suckled for up to 6 hours and prepared for electron microscopy and immunocytochemistry as previously described.

scholarly journals Myxococcus xanthus as a Model Organism for Peptidoglycan Assembly and Bacterial Morphogenesis

2021 ◽  
Vol 9 (5) ◽  
pp. 916
Author(s):  
Huan Zhang ◽  
Srutha Venkatesan ◽  
Beiyan Nan
Keyword(s):  
De Novo ◽  
Myxococcus Xanthus ◽  
Model Organism ◽  
Life Stages ◽  
Negative Bacterium ◽  
Ideal Model ◽  
Daughter Cells ◽  
Bacterial Division ◽  
Cell Shapes ◽  
Rare Opportunity

A fundamental question in biology is how cell shapes are genetically encoded and enzymatically generated. Prevalent shapes among walled bacteria include spheres and rods. These shapes are chiefly determined by the peptidoglycan (PG) cell wall. Bacterial division results in two daughter cells, whose shapes are predetermined by the mother. This makes it difficult to explore the origin of cell shapes in healthy bacteria. In this review, we argue that the Gram-negative bacterium Myxococcus xanthus is an ideal model for understanding PG assembly and bacterial morphogenesis, because it forms rods and spheres at different life stages. Rod-shaped vegetative cells of M. xanthus can thoroughly degrade their PG and form spherical spores. As these spores germinate, cells rebuild their PG and reestablish rod shape without preexisting templates. Such a unique sphere-to-rod transition provides a rare opportunity to visualize de novo PG assembly and rod-like morphogenesis in a well-established model organism.

CFTR gene transfer corrects defective glycoconjugate secretion in human CF epithelial tracheal cells

1995 ◽  
Vol 269 (6) ◽  
pp. L855-L864 ◽  
Author(s):  
M. Mergey ◽  
M. Lemnaouar ◽  
D. Veissiere ◽  
M. Perricaudet ◽  
D. C. Gruenert ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Protein Kinase ◽  
Gene Transfer ◽  
Epithelial Cells ◽  
De Novo ◽  
Tracheal Epithelial Cells ◽  
Normal Human ◽  
Cftr Protein ◽  
Tracheal Epithelial ◽  
And Control

We demonstrate that in immortalized normal human tracheal epithelial cells (NT-1 and 56FHTE8o-) 14C-labeled glycoconjugate secretion may be regulated independently by agonists of the protein kinase A (PKA) and protein kinase C (PKC) signaling pathways. In contrast, in immortalized cystic fibrosis (CF) human tracheal epithelial cells (CFT-1 and CFT-2), regulation is defective for agonists specific for the PKA but not for the PKC pathway. To characterize the involvement of the cystic fibrosis transmembrane conductance regulator (CFTR) in regulated glycoconjugate secretion, we examined the effect of adenovirus-mediated gene transfer of CFTR to CF and control cells. Forty-eight hours after infection, at a multiplicity of infection of 50 plaque-forming units per cell, high levels of CFTR mRNA were detected by reverse transcription-polymerase chain reaction, and de novo synthesis of CFTR protein was demonstrated by immunoblotting. Gene transfer to CF cells restored defective adenosine 3',5'-cyclic monophosphate (cAMP)-dependent secretion not only of chloride but also of glycoconjugates. Taken together, these results argue for a role for CFTR in cAMP-mediated glycoconjugate secretion.

Intestinal absorption of intrinsic factor and B12-intrinsic factor complex

1964 ◽  
Vol 207 (1) ◽  
pp. 27-32 ◽  
Author(s):  
Agna Boass ◽  
T. Hastings Wilson
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Protein Complex ◽  
Soluble Fraction ◽  
Intrinsic Factor ◽  
Vitamin B ◽  
Intestinal Epithelial ◽  
Basal Surface ◽  
Blood Capillaries ◽  
Intestinal Lymphatics

Evidence is presented which suggests that the vitamin B12-intrinsic factor (B12-IF) complex is absorbed into the intestinal epithelial cell. Following incubation of sacs of hamster ileum with B12-IF complex, the tissue was washed, the mucosa was homogenized and assayed for the complex. The soluble fraction from such a mucosal homogenate was found to possess significant amounts of the B12-IF complex. The exit of vitamin B12 from the basal surface of the epithelial cells was investigated by studying its appearance in the intestinal lymphatics. In a series of rats it was found that 3–9% of the absorbed B12 entered the lymphatic capillaries while the remaining fraction (91–97%) passed into the blood capillaries. Vitamin B12 present in lymph, although not dialyzable, was not bound to intrinsic factor. It is inferred from these studies that B12-IF complex enters the intestinal epithelial cells where it is converted into some other B12-protein complex. Following the exit of this B12-protein complex from the epithelial cell, it enters both lymphatic and blood capillaries, the latter being a quantitatively more important route.

scholarly journals Inhibition of Chromosomal Separation Provides Insights into Cleavage Furrow Stimulation in Cultured Epithelial Cells

1998 ◽  
Vol 9 (8) ◽  
pp. 2173-2184 ◽  
Author(s):  
Sally P. Wheatley ◽  
Christopher B. O’Connell ◽  
Yu-li Wang
Keyword(s):  
Epithelial Cells ◽  
Mammalian Cells ◽  
Topoisomerase Ii ◽  
Rat Kidney ◽  
Myosin Ii ◽  
Daughter Cells ◽  
Irregular Shapes ◽  
Anaphase Onset ◽  
Cultured Epithelial Cells ◽  
Normal Rat

While astral microtubules are believed to be primarily responsible for the stimulation of cytokinesis in Echinodermembryos, it has been suggested that a signal emanating from the chromosomal region and mediated by the interzonal microtubules stimulates cytokinesis in cultured mammalian cells. To test this hypothesis, we examined cytokinesis in normal rat kidney cells treated with an inhibitor of topoisomerase II, (+)-1,2-bis(3,5-dioxopiperaz-inyl-1-yl)propane, which prevents the separation of sister chromatids and the formation of a spindle interzone. The majority of treated cells showed various degrees of abnormality in cytokinesis. Furrows frequently deviated from the equatorial plane, twisting daughter cells into irregular shapes. Some cells developed furrows in regions outside the equator or far away from the spindle. In addition, F-actin and myosin II accumulated at the lateral ingressing margins but did not form a continuous band along the equator as in control cells. Imaging of microinjected 5- (and 6-) carboxymtetramethylrhodamine-tubulin revealed that a unique set of microtubules projected out from the chromosomal vicinity upon anaphase onset. These microtubules emanated toward the lateral cortex, where they delineated sites of microtubule bundle formation, cortical ingression, and F-actin and myosin II accumulation. As centrosome integrity and astral microtubules appeared unperturbed by (+)-1,2-bis(3,5-dioxopiperaz-inyl-1-yl)propane treatment, the present observations cannot be easily explained by the conventional model involving astral microtubules. We suggest that in cultured epithelial cells the organization of the chromosomes dictates the organization of midzone microtubules, which in turn determines and maintains the cleavage activity.

Effect of defensins on interleukin-8 synthesis in airway epithelial cells

1997 ◽  
Vol 272 (5) ◽  
pp. L888-L896 ◽  
Author(s):  
S. Van Wetering ◽  
S. P. Mannesse-Lazeroms ◽  
M. A. Van Sterkenburg ◽  
M. R. Daha ◽  
J. H. Dijkman ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Neutrophil Elastase ◽  
Proteinase Inhibitor ◽  
De Novo ◽  
Tissue Injury ◽  
A549 Cells ◽  
Airway Epithelial Cells ◽  
Epithelial Cell Line ◽  
Mrna Levels ◽  
Airway Epithelial

Neutrophils play an important role in inflammatory processes in the lung and may cause tissue injury through, for example, release of proteinases such as neutrophil elastase. In addition to neutrophil elastase, stimulated neutrophils also release small nonenzymatic and cationic polypeptides termed defensins. The aim of the present study was to investigate whether defensins induce interleukin (IL)-8 expression in cells of the A549 lung epithelial cell line and in human primary bronchial epithelial cells (PBEC). Supernatants of defensin-treated A549 cells contained increased neutrophil chemotactic activity (16-fold) that was inhibited by antibodies against IL-8. Concurrently, within 3 and 6 h, defensins significantly increased the IL-8 levels in supernatants of both A549 cells (n = 6, P < 0.05 and P < 0.01, respectively) and PBEC (n = 4, P < 0.001 and P < 0.001, respectively). This defensin-induced increase was fully inhibited by the serine proteinase inhibitor alpha 1-proteinase inhibitor. In addition, defensins also increased IL-8 mRNA levels (12-fold); this increase was dependent on de novo mRNA synthesis and did not require protein synthesis. Furthermore, defensins did not affect IL-8 mRNA stability, indicating that the enhanced IL-8 expression was due to increased transcription. Our findings suggest that defensins, released by stimulated neutrophils, stimulate IL-8 synthesis by airway epithelial cells and thus may mediate the recruitment of additional neutrophils into the airways.

scholarly journals RENEWAL OF CELLS WITHIN TASTE BUDS

1965 ◽  
Vol 27 (2) ◽  
pp. 263-272 ◽  
Author(s):  
Lloyd M. Beidler ◽  
Ronald L. Smallman
Keyword(s):  
Epithelial Cells ◽  
Life Span ◽  
Tritiated Thymidine ◽  
Mitotic Division ◽  
Considerable Change ◽  
Chemical Stimulation ◽  
Taste Bud ◽  
Average Cell ◽  
Daughter Cells ◽  
Rat Tongue

Colchicine blocks mitotic division of the epithelial cells surrounding the taste bud of the rat tongue. Response to chemical stimulation decreases 50 per cent 3 hours after colchicine injection as measured by recording the electrical activity from the taste nerve bundle. Radioautography, using tritiated thymidine, shows that those epithelial cells surrounding the taste bud divide and that some of the daughter cells enter the taste bud and slowly move toward the center. The life span of the average cell is about 250 ± 50 hours, although some cells have a much shorter and others a much longer life span. These studies suggest that the cells within the taste bud, as well as the nerves, undergo considerable change with time. Corresponding changes in function are considered.

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