(pinocytosis) articles in PubMed
- The microvascular alterations in frontal cortex during treatment with antipsychotics: a post-mortem study. [Journal Article]
- Rom J Morphol Embryol 2016; 57(2):501-6RJ
- CONCLUSIONS: The evidences shown in our study highlight the fact that antipsychotics with potent antagonist action on D2 receptors may affect the neurovascular unit and small vessels in frontal cortex by altering the balance vasoconstriction-vasodilatation, thus reducing the blood flow and metabolism and generating structural microvascular changes proportional with the level of apoptosis at this level. The functional integrity of the dopaminergic system in frontal cortex depends on the vascular support and the capabilities of the neurovascular unit and any dysfunction increases the neuronal loss with clinically significant changes.The pathological data of our study raises the hypothesis for the pathogenic stages at the level of microvessels in the frontal cortex of the patients with schizophrenia or schizophrenia-spectrum disorders treated with D2-blocking antipsychotics: a stage with functional, reversible alterations that may be correlated with the impairments of working memory and presence of extrapyramidal symptoms and a lesional, irreversible stage with significant deterioration of cognition and global functioning. Further studies are needed to verify this hypothesis.
- Nox2-Mediated PI3K and Cofilin Activation Confers Alternate Redox Control of Macrophage Pinocytosis. [Journal Article]
- Antioxid Redox Signal 2016 Sep 13AR
- CONCLUSIONS: In summary, these findings demonstrate a novel Nox2-mediated mechanism of solute uptake via macropinocytosis, with broad implications for both general cellular physiology and pathological processes. The redox mechanism described here may also identify new targets in atherosclerosis and other disease conditions involving macropinocytosis. Antioxid. Redox Signal. 00, 000-000.
- Poly (l-γ-glutamylglutamine) Polymer Enhances Doxorubicin Accumulation in Multidrug Resistant Breast Cancer Cells. [Journal Article]
- Molecules 2016; 21(6)M
- CONCLUSIONS: This study indicated that both polymer-drug conjugate and unconjugated complex are promising strategies of overcoming resistance of anti-tumor drugs.
- Distinct Cellular Pathways for Induction of CD4+ T Cell-Dependent Antibody Responses to Antigen Expressed by Intact Bacteria Versus Isolated Soluble Antigen. [Journal Article]
- J Immunol 2016 May 15; 196(10):4204-13JI
- Uptake of intact bacteria and soluble Ags by APCs is mediated by phagocytosis and endocytosis or pinocytosis, respectively. Thus, we predicted that injection of clodronate-containing liposomes (CLs),...
Uptake of intact bacteria and soluble Ags by APCs is mediated by phagocytosis and endocytosis or pinocytosis, respectively. Thus, we predicted that injection of clodronate-containing liposomes (CLs), which selectively deplete cells efficient in phagocytosis, would inhibit murine CD4(+) T cell-dependent IgG responses to Ags expressed by intact bacteria but not isolated soluble Ags. Surprisingly, injection of CLs markedly inhibited protein-specific IgG responses to intact, heat-killed Streptococcus pneumoniae, as well as a soluble OVA-polysaccharide conjugate or OVA alone. IgG anti-polysaccharide responses to bacteria and conjugate were also reduced, but more modestly. In both instances, CL-mediated inhibition was associated with a significant reduction in induced germinal centers and CD4(+) germinal center T follicular helper cells. However, CL injection, which largely abrogated the proliferative response of adoptively transferred OVA peptide-specific-transgenic CD4(+) T cells in response to immunization with S. pneumoniae expressing OVA peptide, did not inhibit T cell proliferation in response to OVA-polysaccharide conjugate or OVA. In this regard, monocyte-derived cells, depleted by CLs, internalized S. pneumoniae in vivo, whereas CD11c(low) dendritic cells, unaffected by CL injection, internalized soluble OVA. Ex vivo isolation and coculture of these respective APCs from S. pneumoniae- or OVA-immunized mice with OVA-specific T cells, in the absence of exogenous Ag, demonstrated their selective ability to induce T cell activation. These data suggest that, although distinct APCs initiate CD4(+) T cell activation in response to Ag expressed by intact bacteria versus Ag in soluble form, CL-sensitive cells appear to be necessary for the subsequent IgG responses to both forms of Ag.
- Calcium-sensing receptors signal constitutive macropinocytosis and facilitate the uptake of NOD2 ligands in macrophages. [Journal Article]
- Nat Commun 2016; 7:11284NC
- Macropinocytosis can be induced in several cell types by stimulation with growth factors. In selected cell types, notably macrophages and dendritic cells, macropinocytosis occurs constitutively, supp...
Macropinocytosis can be induced in several cell types by stimulation with growth factors. In selected cell types, notably macrophages and dendritic cells, macropinocytosis occurs constitutively, supporting the uptake of antigens for subsequent presentation. Despite their different mode of initiation and contrasting physiological roles, it is tacitly assumed that both types of macropinocytosis are mechanistically identical. We report that constitutive macropinocytosis is stringently calcium dependent, while stimulus-induced macropinocytosis is not. Extracellular calcium is sensed by G-protein-coupled calcium-sensing receptors (CaSR) that signal macropinocytosis through Gα-, phosphatidylinositol 3-kinase and phospholipase C. These pathways promote the recruitment of exchange factors that stimulate Rac and/or Cdc42, driving actin-dependent formation of ruffles and macropinosomes. In addition, the heterologous expression of CaSR in HEK293 cells confers on them the ability to perform constitutive macropinocytosis. Finally, we show that CaSR-induced constitutive macropinocytosis facilitates the sentinel function of macrophages, promoting the efficient delivery of ligands to cytosolic pattern-recognition receptors.
- Attacking the supply wagons to starve cancer cells to death. [Review]
- FEBS Lett 2016; 590(7):885-907FL
- The constitutive anabolism of cancer cells not only supports proliferation but also addicts tumor cells to a steady influx of exogenous nutrients. Limiting access to metabolic substrates could be an ...
The constitutive anabolism of cancer cells not only supports proliferation but also addicts tumor cells to a steady influx of exogenous nutrients. Limiting access to metabolic substrates could be an effective and selective means to block cancer growth. In this review, we define the pathways by which cancer cells acquire the raw materials for anabolism, highlight the actionable proteins in each pathway, and discuss the status of therapeutic interventions that disrupt nutrient acquisition. Critical open questions to be answered before apical metabolic inhibitors can be successfully and safely deployed in the clinic are also outlined. In summary, recent studies provide strong support that substrate limitation is a powerful therapeutic strategy to effectively, and safely, starve cancer cells to death.
- Lipoprotein X Causes Renal Disease in LCAT Deficiency. [Journal Article]
- PLoS One 2016; 11(2):e0150083Plos
- Human familial lecithin:cholesterol acyltransferase (LCAT) deficiency (FLD) is characterized by low HDL, accumulation of an abnormal cholesterol-rich multilamellar particle called lipoprotein-X (LpX)...
Human familial lecithin:cholesterol acyltransferase (LCAT) deficiency (FLD) is characterized by low HDL, accumulation of an abnormal cholesterol-rich multilamellar particle called lipoprotein-X (LpX) in plasma, and renal disease. The aim of our study was to determine if LpX is nephrotoxic and to gain insight into the pathogenesis of FLD renal disease. We administered a synthetic LpX, nearly identical to endogenous LpX in its physical, chemical and biologic characteristics, to wild-type and Lcat-/- mice. Our in vitro and in vivo studies demonstrated an apoA-I and LCAT-dependent pathway for LpX conversion to HDL-like particles, which likely mediates normal plasma clearance of LpX. Plasma clearance of exogenous LpX was markedly delayed in Lcat-/- mice, which have low HDL, but only minimal amounts of endogenous LpX and do not spontaneously develop renal disease. Chronically administered exogenous LpX deposited in all renal glomerular cellular and matrical compartments of Lcat-/- mice, and induced proteinuria and nephrotoxic gene changes, as well as all of the hallmarks of FLD renal disease as assessed by histological, TEM, and SEM analyses. Extensive in vivo EM studies revealed LpX uptake by macropinocytosis into mouse glomerular endothelial cells, podocytes, and mesangial cells and delivery to lysosomes where it was degraded. Endocytosed LpX appeared to be degraded by both human podocyte and mesangial cell lysosomal PLA2 and induced podocyte secretion of pro-inflammatory IL-6 in vitro and renal Cxl10 expression in Lcat-/- mice. In conclusion, LpX is a nephrotoxic particle that in the absence of Lcat induces all of the histological and functional hallmarks of FLD and hence may serve as a biomarker for monitoring recombinant LCAT therapy. In addition, our studies suggest that LpX-induced loss of endothelial barrier function and release of cytokines by renal glomerular cells likely plays a role in the initiation and progression of FLD nephrosis.
- Experimental study of super paramagnetic iron oxide labeled synovial mesenchymal stem cells. [Journal Article]
- Int J Clin Exp Med 2015; 8(11):20309-15IJ
- To investigate the feasibility and changes of biological characteristics before and after synovial mesenchymal stem cells (SMSCs) labelled by super paramagnetic iron oxide (SPIO). The rabbit SMSCs we...
To investigate the feasibility and changes of biological characteristics before and after synovial mesenchymal stem cells (SMSCs) labelled by super paramagnetic iron oxide (SPIO). The rabbit SMSCs were isolated, cultured, purified and identified in vitro. After adding the different concentrations of SPIO-labelled liquid, the cells were incubated 24 h in 37°C carbon dioxide incubator. The labeled-cell samples were observed by Prussian blue staining, transmission electron microscope (TEM) and the cell biology before and after the labeling was compared. The blue stained particles could be seen in the cytoplasm; the SPIO label was positive in 95% SMSC cells. With the concentration of the label liquid increasing, the blue-stained cytoplasm became darker. A large number of high electron density particles could be seen in the cytoplasm and in the pinocytosis vesicles by TEM, which suggested SPIO label positive. When the SPIO concentration was (12.5~50) μg/mL, the differences in cell proliferation and cell viability between the SMSCs after labelling and the SMSCs before labelling were not significant; when the concentration was over 100 μg/mL, the cell proliferation and cell viability were inhibited. A certain concentration range of SPIO can safely label the rabbit SMSC according to this study, which is important for solving the problem of tracing SMSCs in the joints.
- D-Alanylation of Teichoic Acids and Loss of Poly-N-Acetyl Glucosamine in Staphylococcus aureus during Exponential Growth Phase Enhance IL-12 Production in Murine Dendritic Cells. [Journal Article]
- PLoS One 2016; 11(2):e0149092Plos
- Staphylococcus aureus is a major human pathogen that has evolved very efficient immune evading strategies leading to persistent colonization. During different stages of growth, S. aureus express vari...
Staphylococcus aureus is a major human pathogen that has evolved very efficient immune evading strategies leading to persistent colonization. During different stages of growth, S. aureus express various surface molecules, which may affect the immune stimulating properties, but very little is known about their role in immune stimulation and evasion. Depending on the growth phase, S. aureus may affect antigen presenting cells differently. Here, the impact of growth phases and the surface molecules lipoteichoic acid, peptidoglycan and poly-N-acetyl glucosamine on the induction of IL-12 imperative for an efficient clearance of S. aureus was studied in dendritic cells (DCs). Exponential phase (EP) S. aureus was superior to stationary phase (SP) bacteria in induction of IL-12, which required actin-mediated endocytosis and endosomal acidification. Moreover, addition of staphylococcal cell wall derived peptidoglycan to EP S. aureus stimulated cells increased bacterial uptake but abrogated IL-12 induction, while addition of lipoteichoic acid increased IL-12 production but had no effect on the bacterial uptake. Depletion of the capability to produce poly-N-acetyl glucosamine increased the IL-12 inducing activity of EP bacteria. Furthermore, the mutant dltA unable to produce D-alanylated teichoic acids failed to induce IL-12 but like peptidoglycan and the toll-like receptor (TLR) ligands LPS and Pam3CSK4 the mutant stimulated increased macropinocytosis. In conclusion, the IL-12 response by DCs against S. aureus is highly growth phase dependent, relies on cell wall D-alanylation, endocytosis and subsequent endosomal degradation, and is abrogated by receptor induced macropinocytosis.
New Search Next
- C60 fullerene localization and membrane interactions in RAW 264.7 immortalized mouse macrophages. [Journal Article]
- Nanoscale 2016 Feb 21; 8(7):4134-44N
- There continues to be a significant increase in the number and complexity of hydrophobic nanomaterials that are engineered for a variety of commercial purposes making human exposure a significant hea...
There continues to be a significant increase in the number and complexity of hydrophobic nanomaterials that are engineered for a variety of commercial purposes making human exposure a significant health concern. This study uses a combination of biophysical, biochemical and computational methods to probe potential mechanisms for uptake of C60 nanoparticles into various compartments of living immune cells. Cultures of RAW 264.7 immortalized murine macrophage were used as a canonical model of immune-competent cells that are likely to provide the first line of defense following inhalation. Modes of entry studied were endocytosis/pinocytosis and passive permeation of cellular membranes. The evidence suggests marginal uptake of C60 clusters is achieved through endocytosis/pinocytosis, and that passive diffusion into membranes provides a significant source of biologically-available nanomaterial. Computational modeling of both a single molecule and a small cluster of fullerenes predicts that low concentrations of fullerenes enter the membrane individually and produce limited perturbation; however, at higher concentrations the clusters in the membrane causes deformation of the membrane. These findings are bolstered by nuclear magnetic resonance (NMR) of model membranes that reveal deformation of the cell membrane upon exposure to high concentrations of fullerenes. The atomistic and NMR models fail to explain escape of the particle out of biological membranes, but are limited to idealized systems that do not completely recapitulate the complexity of cell membranes. The surprising contribution of passive modes of cellular entry provides new avenues for toxicological research that go beyond the pharmacological inhibition of bulk transport systems such as pinocytosis.