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Molecular Biology of the Cell Sep 2022Arrays of actin filaments (F-actin) near the apical surface of epithelial cells (medioapical arrays) contribute to apical constriction and morphogenesis throughout...
Arrays of actin filaments (F-actin) near the apical surface of epithelial cells (medioapical arrays) contribute to apical constriction and morphogenesis throughout phylogeny. Here, superresolution approaches (grazing incidence structured illumination, GI-SIM, and lattice light sheet, LLSM) microscopy resolve individual, fluorescently labeled F-actin and bipolar myosin filaments that drive amnioserosa cell shape changes during dorsal closure in . In expanded cells, F-actin and myosin form loose, apically domed meshworks at the plasma membrane. The arrays condense as cells contract, drawing the domes into the plane of the junctional belts. As condensation continues, individual filaments are no longer uniformly apparent. As cells expand, arrays of actomyosin are again resolved-some F-actin turnover likely occurs, but a large fraction of existing filaments rearrange. In morphologically isotropic cells, actin filaments are randomly oriented and during contraction are drawn together but remain essentially randomly oriented. In anisotropic cells, largely parallel actin filaments are drawn closer to one another. Our images offer unparalleled resolution of F-actin in embryonic tissue, show that medioapical arrays are tightly apposed to the plasma membrane and are continuous with meshworks of lamellar F-actin. Medioapical arrays thereby constitute modified cell cortex. In concert with other tagged array components, superresolution imaging of live specimens will offer new understanding of cortical architecture and function.
Topics: Actin Cytoskeleton; Actins; Actomyosin; Animals; Drosophila; Microscopy; Myosins
PubMed: 35544300
DOI: 10.1091/mbc.E21-11-0537 -
Methods in Molecular Biology (Clifton,... 2020Conspicuous intracellular gradients manifest and/or drive intracellular polarity in pollen tubes. However, quantifying these gradients raises multiple technical...
Conspicuous intracellular gradients manifest and/or drive intracellular polarity in pollen tubes. However, quantifying these gradients raises multiple technical challenges. Here we present a sensible computational protocol to analyze gradients in growing pollen tubes and to filter nonrepresentative time points. As an example, we use imaging data from pollen tubes expressing a genetically encoded ratiometric Ca probe, Yellow CaMeleon 3.6, from which a kymograph is extracted. The tip of the pollen tube is detected with CHUKNORRIS, our previously published methodology, allowing the reconstruction of the intracellular gradient through time. Statistically confounding time points, such as growth arrest where gradients are highly oscillatory, are filtered out and a mean spatial profile is estimated with a local polynomial regression method. Finally, we estimate the gradient slope by the linear portion of the decay in mean fluorescence, offering a quantitative method to detect phenotypes of gradient steepness, location, intensity, and variability. The data manipulation protocol proposed can be achieved in a simple and efficient manner using the statistical programming language R, opening paths to perform high-throughput spatiotemporal phenotyping of intracellular gradients in apically growing cells.
Topics: Arabidopsis; Calcium; Cell Polarity; Kymography; Metabolic Flux Analysis; Microscopy, Fluorescence; Pollen Tube; Software
PubMed: 32529438
DOI: 10.1007/978-1-0716-0672-8_14 -
Cell Biology International Aug 2023The tiger flatworm Prostheceraeus crozieri (Polycladida) develops via an eight-lobed, and three-eyed planktonic Müller's larva. This larva has an apical organ,...
The tiger flatworm Prostheceraeus crozieri (Polycladida) develops via an eight-lobed, and three-eyed planktonic Müller's larva. This larva has an apical organ, ultrastructural details of which remain elusive due to a scarcity of studies. The evolution and possible homology of the polyclad larva with other spiralian larvae is still controversial. Here, we provide ultrastructural data and three-dimensional reconstructions of the apical organ of P. crozieri. The apical organ consists of an apical tuft complex and a dorso-apical tuft complex. The apical tuft complex features a central tuft of five long cilia, which emerge from four or five individual cells that are themselves encircled by two anchor cells. The necks of six multibranched gland cells are sandwiched between ciliated tuft cell bodies and anchor cells. The proximal parts of the ciliated cell bodies are in contact with the lateral brain neuropil via gap junctions. Located dorsally of the apical tuft complex, the dorso-apical tuft complex is characterized by several long cilia of sensory neurons, these emerge from an epidermal lumen and are closely associated with several gland cells that form a crescent apically around the dorsal anchor cell, and laterally touch the brain neuropil. Such ciliated sensory neurons emerging from a ciliated lumen are reminiscent of ampullary cells of mollusc and annelid larvae; a similar cell type can be found in the hoplonemertean decidula larva. We hypothesize that the ampullary-like cells and the tuft-forming sensory cells in the apical organs of these spiralian larvae could be homologous.
Topics: Animals; Platyhelminths; Tigers; Larva; Mollusca; Cilia
PubMed: 37036275
DOI: 10.1002/cbin.12023 -
Current Biology : CB Sep 2022A key aim in biology is to identify which genetic changes contributed to the evolution of form through time. Apical dominance, the inhibitory effect exerted by shoot...
A key aim in biology is to identify which genetic changes contributed to the evolution of form through time. Apical dominance, the inhibitory effect exerted by shoot apices on the initiation or outgrowth of distant lateral buds, is a major regulatory mechanism of plant form. Nearly a century of studies in the sporophyte of flowering plants have established the phytohormone auxin as a front-runner in the search for key factors controlling apical dominance, identifying critical roles for long-range polar auxin transport and local auxin biosynthesis in modulating shoot branching. A capacity for lateral branching evolved by convergence in the gametophytic shoot of mosses and primed its diversification; however, polar auxin transport is relatively unimportant in this developmental process, the contribution of auxin biosynthesis genes has not been assessed, and more generally, the extent of conservation in apical dominance regulation within the land plants remains largely unknown. To fill this knowledge gap, we sought to identify genetic determinants of apical dominance in the moss Physcomitrium patens. Here, we show that leafy shoot apex decapitation releases apical dominance through massive and rapid transcriptional reprogramming of auxin-responsive genes and altering auxin biosynthesis gene activity. We pinpoint a subset of P. patens TRYPTOPHAN AMINO-TRANSFERASE (TAR) and YUCCA FLAVIN MONOOXYGENASE-LIKE (YUC) auxin biosynthesis genes expressed in the main and lateral shoot apices and show that they are essential for coordinating branch initiation and outgrowth. Our results demonstrate that local auxin biosynthesis acts as a pivotal regulator of apical dominance in moss and constitutes a shared mechanism underpinning shoot architecture control in land plants.
Topics: Bryophyta; Bryopsida; Gene Expression Regulation, Plant; Germ Cells, Plant; Indoleacetic Acids; Plant Growth Regulators; Plant Shoots
PubMed: 35841890
DOI: 10.1016/j.cub.2022.06.064 -
Frontiers in Cell and Developmental... 2021Integrins are transmembrane proteins that are most typically thought of as integrating adhesion to the extracellular matrix with intracellular signaling and cell... (Review)
Review
Integrins are transmembrane proteins that are most typically thought of as integrating adhesion to the extracellular matrix with intracellular signaling and cell regulation. Traditionally, integrins are found at basolateral and lateral cell surfaces where they facilitate binding to the ECM and intercellular adhesion through cytosolic binding partners that regulate organization of actin microfilaments. However, evidence is accumulating that integrins also are apically localized, either endogenously or due to an exogenous stimulus. Apically localized integrins have been shown to regulate several processes by interacting with proteins such as connexins, tight junction proteins, and polarity complex proteins. Integrins can also act as receptors to mediate endocytosis. Here we review these newly appreciated roles for integrins localized to the apical cell surface.
PubMed: 34485286
DOI: 10.3389/fcell.2021.699407 -
Journal of Medical Case Reports Aug 2023Endomyocardial fibrosis is a grim disease. It is the most common restrictive cardiomyopathy worldwide, but the exact etiology and pathogenesis both remain unknown....
BACKGROUND
Endomyocardial fibrosis is a grim disease. It is the most common restrictive cardiomyopathy worldwide, but the exact etiology and pathogenesis both remain unknown. Endomyocardial fibrosis is recurrently associated with chronic eosinophilia and probable dietary, environmental, and infectious factors, which contribute not only to the onset of the disease (an inflammatory process) but also to its progression and maintenance (endomyocardial damage and scar formation). The trademark of the disease is the fibrotic obliteration of the affected ventricle. The combination of such processes produces focal or diffuse endocardial thickening and fibrosis, which leads to restrictive physiology. Endomyocardial fibrosis affects the apices of the right and the left ventricle in around 50% of cases and most often extends to the posterior leaflet of the mitral valve. Sometimes it involves the papillary muscle and chordae tendineae, causing atrioventricular valve dysfunction. The fibrosis does not affect extracardiac organs. This cardiomyopathy is most recurrent in tropical areas of the world.
CASE PRESENTATION
A 67-year-old Black male with past medical history of schistosomiasis infection in childhood presented with progressive dyspnea, lower extremity edema, and weakness for 2 years. He was diagnosed with endomyocardial fibrosis. The echocardiogram showed an increased thickness in the septum (17 mm) and free left ventricular wall (15 mm), obliteration of the left ventricular apex and inflow tract, and mitral valve regurgitation. Cardiac magnetic resonance imaging revealed apical left ventricle wall thickening with left ventricular apical obliteration associated with enlargement of the respective atrium. Delayed enhancement imaging showed endomyocardium enhancement involving left ventricular apex, mitral valve regurgitation due to annulus dilation, and a thrombus at left ventricular apex. He underwent open heart surgery with mitral valve replacement, endocardial decortication, endomyocardiectomy, and two-vessel coronary artery bypass grafting as preoperative coronary angiogram showed mild right coronary artery and proximal left anterior descending artery severe lesions. Postoperative course was uncomplicated, and he was discharged successfully from the hospital. Six months after surgery, he was New York Heart Association functional class I.
CONCLUSION
The purpose of this case report is to illustrate the aspects of endomyocardial fibrosis by reporting a case of this entity. In conclusion, progress in imaging techniques and treatment in a reference institution for cardiac diseases contribute to earlier diagnosis and survival in patients with endomyocardial fibrosis.
Topics: Humans; Male; Aged; Endomyocardial Fibrosis; Heart Ventricles; Mitral Valve Insufficiency; Myocardium; Fibrosis
PubMed: 37568222
DOI: 10.1186/s13256-023-04056-z -
BioRxiv : the Preprint Server For... Apr 2023Extracellular vesicles (EVs) contain bioactive cargo including microRNAs (miRNAs) and proteins that are released by cells as a form of cell-cell communication....
RATIONALE
Extracellular vesicles (EVs) contain bioactive cargo including microRNAs (miRNAs) and proteins that are released by cells as a form of cell-cell communication. Endothelial cells (ECs) form the innermost lining of all blood vessels and thereby interface with cells in the circulation as well as cells residing in the vascular wall. It is unknown whether ECs have the capacity to release EVs capable of governing recipient cells within two separate compartments, and how this is affected by endothelial activation commonly seen in atheroprone regions.
OBJECTIVE
Given their boundary location, we propose that ECs utilize bidirectional release of distinct EV cargo in quiescent and activated states to communicate with cells within the circulation and blood vessel wall.
METHODS AND RESULTS
EVs were isolated from primary human aortic endothelial cells (ECs) (+/-IL-1β activation), quantified, and analysed by miRNA transcriptomics and proteomics. Compared to quiescent ECs, activated ECs increased EV release, with miRNA and protein cargo that were related to atherosclerosis. RNA sequencing of EV-treated monocytes and smooth muscle cells (SMCs) revealed that EVs from activated ECs altered pathways that were pro-inflammatory and atherogenic. Apical and basolateral EV release was assessed using ECs on transwells. ECs released more EVs apically, which increased with activation. Apical and basolateral EV cargo contained distinct transcriptomes and proteomes that were altered by EC activation. Notably, basolateral EC-EVs displayed greater changes in the EV secretome, with pathways specific to atherosclerosis. analysis determined that compartment-specific cargo released by the apical and basolateral surfaces of ECs can reprogram monocytes and SMCs, respectively.
CONCLUSIONS
The demonstration that ECs are capable of polarized EV cargo loading and directional EV secretion reveals a novel paradigm for endothelial communication, which may ultimately enhance our ability to design endothelial-based therapeutics for cardiovascular diseases such as atherosclerosis where ECs are persistently activated.
PubMed: 37162986
DOI: 10.1101/2023.04.28.538787 -
Annals of Botany Dec 2022Aquatic carnivorous plants have typical rootless linear shoots bearing traps and exhibit steep physiological polarity with rapid apical growth. The aim was to analyse...
BACKGROUND AND AIMS
Aquatic carnivorous plants have typical rootless linear shoots bearing traps and exhibit steep physiological polarity with rapid apical growth. The aim was to analyse auxin and cytokinin metabolites in traps, leaves/shoots and shoot apices in several species of genera Aldrovanda and Utricularia to elucidate how the hormonal profiles reflect the specific organ functions and polarity.
METHODS
The main auxin and cytokinin metabolites were analysed in miniature samples (>2 mg dry weight) of different organs of Aldrovanda vesiculosa and six Utricularia species using ultraperformance liquid chromatography coupled with triple quadrupole mass spectrometry.
KEY RESULTS
Total contents of biologically active forms (free bases, ribosides) of all four main endogenously occurring cytokinin types were consistently higher in traps than in leaves in four Utricularia species with monomorphic shoots and/or higher than in shoots in two Utricularia species with dimorphic shoots. In Aldrovanda traps, the total content of different cytokinin forms was similar to or lower than that in shoots. In U. australis leaves, feeding on prey increased all cytokinin forms, while no consistent differences occurred in Aldrovanda. In four aquatic Utricularia species with monomorphic shoots, the content of four auxin forms was usually higher in traps than in leaves. Zero IAA content was determined in U. australis leaves from a meso-eutrophic site or when prey-fed.
CONCLUSIONS
Different cytokinin and auxin profiles estimated in traps and leaves/shoots of aquatic carnivorous plants indicate an association with different dominant functions of these organs: nutrient uptake by traps versus photosynthetic function of traps. Interplay of cytokinins and auxins regulates apical dominance in these plants possessing strong polarity.
Topics: Cytokinins; Carnivorous Plant; Indoleacetic Acids; Magnoliopsida; Droseraceae; Lamiales
PubMed: 36215097
DOI: 10.1093/aob/mcac122 -
Microscopy (Oxford, England) Aug 2022A small number of oncogenic mutated cells sporadically arise within the epithelial monolayer. Newly emerging Ras- or Src-transformed epithelial cells are often apically...
A small number of oncogenic mutated cells sporadically arise within the epithelial monolayer. Newly emerging Ras- or Src-transformed epithelial cells are often apically eliminated during competitive interactions between normal and transformed cells. Our recent electron microscopy (EM) analyses revealed that characteristic finger-like membrane protrusions are formed at the interface between normal and RasV12-transformed cells via the cdc42-formin-binding protein 17 (FBP17) pathway, potentially playing a positive role in intercellular recognition during apical extrusion. However, the spatial distribution and ultrastructural characteristics of finger-like protrusions remain unknown. In this study, we performed both X-Y and X-Z EM analyses of finger-like protrusions during the apical extrusion of RasV12-transformed cells. Quantification of the distribution and widths of the protrusions showed comparable results between the X-Y and X-Z sections. Finger-like protrusions were observed throughout the cell boundary between normal and RasV12 cells, except for apicalmost tight junctions. In addition, a non-cell-autonomous reduction in protrusion widths was observed between RasV12 cells and surrounding normal cells under the mix culture condition. In the finger-like protrusions, intercellular adhesions via thin electron-dense plaques were observed, implying that immature and transient forms of desmosomes, adherens junctions or unknown weak adhesions were distributed. Interestingly, unlike RasV12-transformed cells, Src-transformed cells form fewer evident protrusions, and FBP17 in Src cells is dispensable for apical extrusion. Collectively, these results suggest that the dynamic reorganization of intercellular adhesions via finger-like protrusions may positively control cell competition between normal and RasV12-transformed cells. Furthermore, our data indicate a cell context-dependent diversity in the modes of apical extrusion.
Topics: Cell Competition; Cell Transformation, Neoplastic; Epithelial Cells; Humans
PubMed: 35394538
DOI: 10.1093/jmicro/dfac017 -
Marine Drugs May 2023There is a growing interest in using brown algal extracts thanks to the bioactive substances they produce for adaptation to the marine benthic environment. We evaluated...
There is a growing interest in using brown algal extracts thanks to the bioactive substances they produce for adaptation to the marine benthic environment. We evaluated the anti-aging and photoprotective properties of two types of extracts (50%-ethanol and DMSO) obtained from different portions, i.e., apices and thalli, of the brown seaweed, . The apices of this alga, which grow and develop reproductive structures during summer when solar radiation is at its peak, were postulated to be rich in antioxidant compounds. We determined the chemical composition and pharmacological effects of their extracts and compared them to the thallus-derived extracts. All the extracts contained polyphenols, flavonoids and antioxidants and showed significant biological activities. The hydroalcoholic apices extracts demonstrated the highest pharmacological potential, likely due to the higher content of meroditerpene molecular species. They blocked toxicity in UV-exposed HaCaT keratinocytes and L929 fibroblasts and abated the oxidative stress and the production of pro-inflammatory cytokines, typically released after sunburns. Furthermore, the extracts showed anti-tyrosinase and anti-hydrolytic skin enzyme activity, counteracting the collagenase and hyaluronidase degrading activities and possibly slowing down the formation of uneven pigmentation and wrinkles in aging skin. In conclusion, the apices derivatives constitute ideal components for counteracting sunburn symptoms and for cosmetic anti-aging lotions.
Topics: Seaweed; Polyphenols; Phaeophyceae; Flavonoids; Antioxidants; Plant Extracts
PubMed: 37233500
DOI: 10.3390/md21050306