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Clinical Hemorheology and... Feb 2024Several conventional studies focused on platelet pinocytosis for possible utilization as drug delivery systems. Although platelet pinocytosis is important in such...
BACKGROUND
Several conventional studies focused on platelet pinocytosis for possible utilization as drug delivery systems. Although platelet pinocytosis is important in such utilization, the impact of the shear rate on pinocytosis is unclear.
OBJECTIVE
Our objective was to investigate the relationship between shear rate and platelet pinocytosis in vitro. In addition, this study addressed the change in platelet aggregation reactivity with adenosine diphosphate (ADP) stimulation after pinocytosis.
METHOD
Porcine platelet-rich plasma was mixed with fluorescein isothiocyanate (FITC)-conjugated dextran and incubated for 15 min under shear conditions of 0, 500, and 1500 s-1. After incubation, confocal microscopic scanning and three-dimensional rendering were performed to confirm the internalization of FITC-dextran into platelets. The amount of FITC-dextran accumulated via platelet pinocytosis was compared using flow cytometry at each shear rate. In addition, light transmission aggregometry by ADP stimulation was applied to platelets after pinocytosis.
RESULTS
The amount of intracellular FITC-dextran increased with higher shear rates. Platelets with increased amounts of intracellular FITC-dextran did not show changes in the aggregation reactivity to ADP.
CONCLUSIONS
A higher shear rate promotes platelet pinocytosis, but enhanced pinocytosis does not affect aggregation sensitivity, which is stimulated by ADP.
PubMed: 38393893
DOI: 10.3233/CH-232075 -
Current Opinion in Cell Biology Jun 2024Macropinocytosis (MP), the actin-dependent bulk uptake of extracellular fluids, plays a central role in nutrient scavenging, allowing cancer cells to sustain their... (Review)
Review
Macropinocytosis (MP), the actin-dependent bulk uptake of extracellular fluids, plays a central role in nutrient scavenging, allowing cancer cells to sustain their growth in the hypoxic and nutrient-deprived microenvironment often found in solid tumours. The lack of soluble nutrients and several oncogenic signalling pathways, with RAS being the most studied, push MP-dependent internalisation of extracellular proteins, which are then digested in the lysosomes, replenishing the intracellular nutrient pools. This review will highlight recent advances in understanding how MP is regulated in hypoxic cancers, how it impinges on chemoresistance, and how different MP cargos facilitate tumour growth. Finally, I will highlight the crosstalk between MP and extracellular matrix receptors.
Topics: Humans; Pinocytosis; Neoplasms; Animals; Nutrients; Tumor Microenvironment; Signal Transduction
PubMed: 38626703
DOI: 10.1016/j.ceb.2024.102359 -
Molecular Biology of the Cell Mar 2024Cells rely on a diverse array of engulfment processes to sense, exploit, and adapt to their environments. Among these, macropinocytosis enables indiscriminate and rapid...
Cells rely on a diverse array of engulfment processes to sense, exploit, and adapt to their environments. Among these, macropinocytosis enables indiscriminate and rapid uptake of large volumes of fluid and membrane, rendering it a highly versatile engulfment strategy. Much of the molecular machinery required for macropinocytosis has been well established, yet how this process is regulated in the context of organs and organisms remains poorly understood. Here, we report the discovery of extensive macropinocytosis in the outer epithelium of the cnidarian . Exploiting 's relatively simple body plan, we developed approaches to visualize macropinocytosis over extended periods of time, revealing constitutive engulfment across the entire body axis. We show that the direct application of planar stretch leads to calcium influx and the inhibition of macropinocytosis. Finally, we establish a role for stretch-activated channels in inhibiting this process. Together, our approaches provide a platform for the mechanistic dissection of constitutive macropinocytosis in physiological contexts and highlight a potential role for macropinocytosis in responding to cell surface tension.
Topics: Animals; Hydra; Pinocytosis
PubMed: 38265917
DOI: 10.1091/mbc.E22-02-0065 -
Molecular Pharmaceutics Dec 2023Lipid nanoparticle (LNP) constructs have been widely developed for gene therapy delivery. Understanding local absorption and presystemic clearance kinetics of LNPs,...
Lipid nanoparticle (LNP) constructs have been widely developed for gene therapy delivery. Understanding local absorption and presystemic clearance kinetics of LNPs, however, remains limited. This subsequently restrains the prediction and assessment of the systemic exposure of locally injected LNPs. As such, a multiscale computational approach was developed by integrating multiphysics simulation of intramuscular absorption kinetics of LNPs with whole-body pharmacokinetics modeling, bridged by a presystemic lymphatic kinetic model. The overall framework was enabled by utilizing physiological parameters obtained from the literature and drug-related parameters derived from experiments. The multiscale modeling and simulation approach predicted the systemic exposure of LNPs administered intramuscularly, with a high degree of agreement between the predicted and the experimental data. Sensitivity analyses revealed that the local absorption rate, pinocytosis presystemic clearance rate, and lymph flow rate of the presystemic lymphatic compartment had the most significant impacts on . The study yielded refreshing perspectives on estimating systemic exposures of locally injected LNPs and their safety and effectiveness.
Topics: Gene Transfer Techniques; Genetic Therapy; Nanoparticles; Lipids; Computer Simulation; RNA, Small Interfering
PubMed: 37919256
DOI: 10.1021/acs.molpharmaceut.3c00555 -
Methods in Molecular Biology (Clifton,... 2024Microglia are scavengers of the brain environment that clear dead cells, debris, and microbes. In Alzheimer's disease, microglia get activated to phagocytose damaged...
Microglia are scavengers of the brain environment that clear dead cells, debris, and microbes. In Alzheimer's disease, microglia get activated to phagocytose damaged neurons, extracellular Amyoid-β, and Tau deposits. Several Tau internalization mechanisms of microglia have been studied which include phagocytosis, pinocytosis, and receptor-mediated endocytosis. In this chapter, we have visualized microglial phagocytic structures that are actin-rich cup-like extensions, which surrounds extracellular Tau species by wide-field fluorescence and confocal microscopy. We have shown the association of filamentous actin in Tau phagocytosis along the assembly of LC-3 molecules to phagosomes. The 3-dimensional, orthogonal and gallery wise representation of these phagocytic structures provides an overview of the phagocytic mechanism of extracellular Tau by microglia.
Topics: Humans; Microglia; Actins; Alzheimer Disease; Phagocytosis; Biological Transport; Amyloid beta-Peptides
PubMed: 38427240
DOI: 10.1007/978-1-0716-3662-6_16 -
Brain and Nerve = Shinkei Kenkyu No... Feb 2024Neonatal Fc receptor (FcRn) is involved in recycling of IgG. Recycling begins with IgG-uptake into the cell through pinocytosis. Subsequently, IgG binds to FcRn in...
Neonatal Fc receptor (FcRn) is involved in recycling of IgG. Recycling begins with IgG-uptake into the cell through pinocytosis. Subsequently, IgG binds to FcRn in acidic vesicles, which results in the recycling of the FcRn-IgG complex to cell surface, and the release of IgG in blood with neutral pH. Whereas IgG unbound to FcRn is not recycled and thus degraded in lysosomes. Therefore, FcRn plays a critical role in maintaining IgG levels in the blood. Recently, FcRn has been considered a therapeutic target for autoimmune diseases caused by IgG autoantibodies, and FcRn inhibitors are developed as therapeutic agents for the diseases. As one example, the administration of an FcRn inhibitor, efgartigimod, reduced IgG and anti-acetylcholine receptor antibody levels in patients with generalized myasthenia gravis (gMG), and improved Myasthenia Gravis Activities of Daily Living score in the phase III trial. In 2022, Efgartigimod Alfa was approved for the treatment of gMG (only when treatment with steroids or non-steroidal immunosuppressive drugs do not lead to sufficient response), regardless of antibody status in Japan. Since FcRn inhibitors have just begun to be used in clinical practice, it is important to accumulate real-world data regarding their efficacy and safety. (Received August 21, 2023; Accepted October 6, 2023; Published February 1, 2024).
Topics: Infant, Newborn; Humans; Activities of Daily Living; Immunoglobulin G; Receptors, Fc; Myasthenia Gravis; Autoantibodies; Histocompatibility Antigens Class I
PubMed: 38351566
DOI: 10.11477/mf.1416202582 -
Journal of the Science of Food and... Jun 2024Walnut protein (WP) is recognized as a valuable plant protein. However, the poor solubility and functional properties limit its application in the food industry. It is a...
BACKGROUND
Walnut protein (WP) is recognized as a valuable plant protein. However, the poor solubility and functional properties limit its application in the food industry. It is a great requirement to improve the physicochemical properties of WP.
RESULTS
Following a 90 min restricted enzymatic hydrolysis period, the solubility of WP significantly increased from 3.24% to 54.54%, with the majority of WP hydrolysates (WPHs) possessing a molecular weight exceeding 50 kDa. Circular dichroism spectra showed that post-hydrolysis, the structure of the protein became more flexible, while the hydrolysis time did not significantly alter the protein's secondary structure. After hydrolysis, WP's surface hydrophobicity significantly increased from 2279 to 6100. Furthermore, WPHs exhibited a strong capacity for icariin loading and micelle formation with critical micelle concentration values of 0.71, 0.99 and 1.09 mg mL, respectively. Moreover, similar immuno-enhancement activities were observed in WPHs. After exposure to WPHs, the pinocytosis of RAW264.7 macrophages was significantly improved. WPH treatment also increased the production of nitric oxide, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in macrophages. Up-regulation of mRNA expressions of IL-6, inducible nitric oxide synthase (iNOS) and TNF-α was observed in a dose-dependent manner.
CONCLUSION
The enhancement of functionality and bioactivity in WP can be achieved through the application of limited enzyme digestion with trypsin. This process effectively augments the nutritional value and utility of the protein, making it a valuable component in various dietary applications. © 2024 Society of Chemical Industry.
PubMed: 38899487
DOI: 10.1002/jsfa.13666 -
Frontiers in Cellular and Infection... 2023is the main causative agent of hospital-acquired diarrhea and the potentially lethal disease, infection. The cornerstone of the current therapy is the use of...
is the main causative agent of hospital-acquired diarrhea and the potentially lethal disease, infection. The cornerstone of the current therapy is the use of antibiotics, which is not fully effective. The molecular mechanisms, inflammatory conditions and host-immune responses that could benefit the persistence or elimination of remain unclear. Macrophages perform different ways of endocytosis as part of their immune surveillance functions and platelets, classically known for their coagulatory role, are also important modulators of the immune system. The aim of this study was to evaluate the endocytosis of vegetative by human macrophages and the involvement of platelets in this process. Our results showed that both macrophages and platelets interact with live and heat-killed . Furthermore, platelets form complexes with human monocytes in healthy donor's fresh blood and the presence of increased these cell-cell interactions. Using flow cytometry and confocal microscopy, we show that macrophages can internalize and that platelets improve this uptake. By using inhibitors of different endocytic pathways, we demonstrate that macropinocytosis is the route of entry of into the cell. Taken together, our findings are the first evidence for the internalization of vegetative non-toxigenic and hypervirulent by human macrophages and highlight the role of platelets in innate immunity during infection. Deciphering the crosstalk of with immune cells could provide new tools for understanding the pathogenesis of infection and for the development of host-directed therapies.
Topics: Humans; Clostridioides difficile; Clostridioides; Blood Platelets; Macrophages; Pinocytosis
PubMed: 38249298
DOI: 10.3389/fcimb.2023.1252509 -
Cell and Tissue Research Nov 2023Intestinal absorption is essential for heterotrophic bilaterians with a tubular gut. Although the fundamental features of the digestive system were shared among...
Intestinal absorption is essential for heterotrophic bilaterians with a tubular gut. Although the fundamental features of the digestive system were shared among chordates with evolution, the gut morphologies of vertebrates diverged and adapted to different food habitats. The ascidian Ciona intestinalis type A, a genome-wide research model of basal chordates, is used to examine the functional morphology of the intestines because of its transparent juvenile body. In the present study, the characteristic gene expression patterns (GEP) of Ciona absorptive proteins, e.g., brush border membrane enzymes for terminal digestion (lactase, maltase, APA, and APN) and transporters (SGLT1, GLUT5, PEPT1, and BAT1), were investigated in juveniles and young adults, with a special reference to the absorption of other nutrients by pinocytosis- and phagocytosis-related proteins (megalin, cubilin, amnionless, Dab2, Rab7, LAMP, cathepsins, and MRC1). Whole-mount in situ hybridization revealed that these GEP showed multi-regional and repetitive features along the Ciona gastrointestinal tract, mainly in the stomach and several regions of the intestines. In young adults, many absorption-related genes, including pinocytosis-/phagocytosis-related genes, were also expressed between the stomach and mid-intestine. In the gastrointestinal epithelium, absorption-related genes showed zonal GEP along the epithelial structure. Comparisons of GEP, including other intestinal functions, such as nutrient digestion and intestinal protection, indicated the repetitive assignment of a well-coordinated set of intestinal GEP in the Ciona gastrointestinal tract.
Topics: Animals; Ciona intestinalis; Gastrointestinal Tract; Vertebrates; Genome; In Situ Hybridization
PubMed: 37670165
DOI: 10.1007/s00441-023-03828-9 -
Biology Open Nov 2023Autotaxin, encoded by the Enpp2 gene, is an exoenzyme that produces lysophosphatidic acid, thereby regulating many biologic functions. We previously reported that Enpp2...
Autotaxin, encoded by the Enpp2 gene, is an exoenzyme that produces lysophosphatidic acid, thereby regulating many biologic functions. We previously reported that Enpp2 mRNA was abundantly expressed in yolk sac visceral endoderm (VE) cells and that Enpp2-/- mice were lethal at embryonic day 9.5 owing to angiogenic defects in the yolk sac. Enpp2-/- mice showed lysosome fragmentation in VE cells and embryonic abnormalities including allantois malformation, neural tube defects, no axial turning, and head cavity formation. However, whether the defects in endocytic vesicle formation affect membrane trafficking in VE cells remained to be directly examined. In this study, we found that pinocytosis, transcytosis, and secretion of angiogenic factors such as vascular endothelial growth factor and transforming growth factor β1 were impaired in Enpp2-/- VE cells. Moreover, pharmacologic inhibition of membrane trafficking phenocopied the defects of Enpp2-/- mice. These findings demonstrate that Enpp2 promotes endocytosis and secretion of angiogenic factors in VE cells, thereby regulating angiogenesis/vasculogenesis and embryonic development.
Topics: Animals; Female; Mice; Pregnancy; Cell Differentiation; Embryonic Development; Endoderm; Vascular Endothelial Growth Factor A; Yolk Sac; Phosphoric Diester Hydrolases
PubMed: 37795611
DOI: 10.1242/bio.060081