scholarly journals Localization of calcium in roots and microsomal membranes of corn by direct pyroantimonate precipitation.

1987 ◽  
Vol 35 (7) ◽  
pp. 781-788 ◽  
Author(s):  
M A Vaughan ◽  
T J Mulkey ◽  
C W Goff
Keyword(s):  
Plasma Membrane ◽  
Calcium Transport ◽  
Intact Cell ◽  
Root Cells ◽  
Meristematic Cells ◽  
Calcium Sequestration ◽  
Corn Roots ◽  
Microsomal Membranes

Many cell membrane systems, including microsomal vesicles of corn, are able to regulate calcium levels both in vivo and in vitro, often in an ATP-dependent, calmodulin-stimulated fashion. The purpose of this study was to determine calcium distribution in meristematic cells of intact tissue and microsomal vesicles from corn roots using direct pyroantimonate-osmium fixation. In root cells, precipitates were localized in mitochondria, plastids, the nucleus, endoplasmic reticulum, Golgi apparatus, and along the plasma membrane. Plasma membrane-enriched microsomal vesicles isolated from corn roots incubated in media to permit calcium transport before pyroantimonate-osmium fixation show internal precipitates associated with the membrane and in the lumen of the vesicles. De-staining of the sections with 1 mM EDTA or EGTA removed precipitate from the sections, confirming the presence of calcium in the antimonate precipitates. These data support biochemical data that this same membrane preparation exhibited ATP-dependent calcium sequestration that was stimulated by calmodulin, as measured by retention of 45Ca. This provides evidence that these membranes are responsible for ATP-requiring, calmodulin-stimulated calcium transport in the intact cell.

Calcium-transport function of the chick embryonic chorioallantoic membrane. I. In vivo and in vitro characterization

1986 ◽  
Vol 82 (1) ◽  
pp. 73-84
Author(s):  
R.S. Tuan ◽  
M.J. Carson ◽  
J.A. Jozefiak ◽  
K.A. Knowles ◽  
B.A. Shotwell
Keyword(s):  
Calcium Transport ◽  
Calcium Uptake ◽  
Chorioallantoic Membrane ◽  
Transport Function ◽  
In Ovo ◽  
In Vitro Characterization ◽  
Microsomal Membranes

During chick embryonic development, the chorioallantoic membrane (CAM) is responsible for the mobilization of shell calcium into the embryonic circulation. The calcium-transport function of the CAM was studied here by measuring CAM calcium uptake in vivo and in vitro. The in vivo technique involved the use of an uptake chamber constructed on top of the CAM in situ. The in vitro methods included two systems: CAM tissue disks and cell-free microsomal membranes isolated from the CAM. Analyses using these three assays show that calcium uptake by the CAM exhibited characteristics indicative of active transport, such as temperature dependence, saturability, energetic requirement and ion specificity. The data also show that calcium-uptake activities of the CAM increase as a function of embryonic age in a manner coincident with the increased accumulation of calcium by the developing embryo in ovo.

scholarly journals RNF141 interacts with KRAS to promote colorectal cancer progression

Oncogene ◽  
2021 ◽  
Author(s):  
Jiuna Zhang ◽  
Xiaoyu Jiang ◽  
Jie Yin ◽  
Shiying Dou ◽  
Xiaoli Xie ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Plasma Membrane ◽  
Tumor Growth ◽  
Cancer Progression ◽  
Critical Role ◽  
Ring Finger ◽  
Immunohistochemical Analysis ◽  
Bimolecular Fluorescence Complementation

AbstractRING finger proteins (RNFs) play a critical role in cancer initiation and progression. RNF141 is a member of RNFs family; however, its clinical significance, roles, and mechanism in colorectal cancer (CRC) remain poorly understood. Here, we examined the expression of RNF141 in 64 pairs of CRC and adjacent normal tissues by real-time PCR, Western blot, and immunohistochemical analysis. We found that there was more expression of RNF141 in CRC tissue compared with its adjacent normal tissue and high RNF141 expression associated with T stage. In vivo and in vitro functional experiments were conducted and revealed the oncogenic role of RNF141 in CRC. RNF141 knockdown suppressed proliferation, arrested the cell cycle in the G1 phase, inhibited migration, invasion and HUVEC tube formation but promoted apoptosis, whereas RNF141 overexpression exerted the opposite effects in CRC cells. The subcutaneous xenograft models showed that RNF141 knockdown reduced tumor growth, but its overexpression promoted tumor growth. Mechanistically, liquid chromatography-tandem mass spectrometry indicated RNF141 interacted with KRAS, which was confirmed by Co-immunoprecipitation, Immunofluorescence assay. Further analysis with bimolecular fluorescence complementation (BiFC) and Glutathione-S-transferase (GST) pull-down assays showed that RNF141 could directly bind to KRAS. Importantly, the upregulation of RNF141 increased GTP-bound KRAS, but its knockdown resulted in a reduction accordingly. Next, we demonstrated that RNF141 induced KRAS activation via increasing its enrichment on the plasma membrane not altering total KRAS expression, which was facilitated by the interaction with LYPLA1. Moreover, KRAS silencing partially abolished the effect of RNF141 on cell proliferation and apoptosis. In addition, our findings presented that RNF141 functioned as an oncogene by upregulating KRAS activity in a manner of promoting KRAS enrichment on the plasma membrane in CRC.

scholarly journals Influence of Oxidative Stress on Time-Resolved Oxygen Detection by [Ru(Phen)3]2+ In Vivo and In Vitro

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 485
Author(s):  
Veronika Huntosova ◽  
Denis Horvath ◽  
Robert Seliga ◽  
Georges Wagnieres
Keyword(s):  
Oxidative Stress ◽  
Tissue Oxygenation ◽  
Intact Cell ◽  
Molecular Probes ◽  
Stress Factors ◽  
Time Resolved ◽  
Invasive Approach ◽  
Oxygen Detection

Detection of tissue and cell oxygenation is of high importance in fundamental biological and in many medical applications, particularly for monitoring dysfunction in the early stages of cancer. Measurements of the luminescence lifetimes of molecular probes offer a very promising and non-invasive approach to estimate tissue and cell oxygenation in vivo and in vitro. We optimized the evaluation of oxygen detection in vivo by [Ru(Phen)3]2+ in the chicken embryo chorioallantoic membrane model. Its luminescence lifetimes measured in the CAM were analyzed through hierarchical clustering. The detection of the tissue oxygenation at the oxidative stress conditions is still challenging. We applied simultaneous time-resolved recording of the mitochondrial probe MitoTrackerTM OrangeCMTMRos fluorescence and [Ru(Phen)3]2+ phosphorescence imaging in the intact cell without affecting the sensitivities of these molecular probes. [Ru(Phen)3]2+ was demonstrated to be suitable for in vitro detection of oxygen under various stress factors that mimic oxidative stress: other molecular sensors, H2O2, and curcumin-mediated photodynamic therapy in glioma cancer cells. Low phototoxicities of the molecular probes were finally observed. Our study offers a high potential for the application and generalization of tissue oxygenation as an innovative approach based on the similarities between interdependent biological influences. It is particularly suitable for therapeutic approaches targeting metabolic alterations as well as oxygen, glucose, or lipid deprivation.

scholarly journals Norepinephrine Protects against Methamphetamine Toxicity through β2-Adrenergic Receptors Promoting LC3 Compartmentalization

2021 ◽  
Vol 22 (13) ◽  
pp. 7232
Author(s):  
Gloria Lazzeri ◽  
Carla L. Busceti ◽  
Francesca Biagioni ◽  
Cinzia Fabrizi ◽  
Gabriele Morucci ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Light Chain ◽  
Adrenergic Receptors ◽  
Cell Damage ◽  
Protective Effects ◽  
Autophagy Flux ◽  
Brain Areas ◽  
Indirect Consequence

Norepinephrine (NE) neurons and extracellular NE exert some protective effects against a variety of insults, including methamphetamine (Meth)-induced cell damage. The intimate mechanism of protection remains difficult to be analyzed in vivo. In fact, this may occur directly on target neurons or as the indirect consequence of NE-induced alterations in the activity of trans-synaptic loops. Therefore, to elude neuronal networks, which may contribute to these effects in vivo, the present study investigates whether NE still protects when directly applied to Meth-treated PC12 cells. Meth was selected based on its detrimental effects along various specific brain areas. The study shows that NE directly protects in vitro against Meth-induced cell damage. The present study indicates that such an effect fully depends on the activation of plasma membrane β2-adrenergic receptors (ARs). Evidence indicates that β2-ARs activation restores autophagy, which is impaired by Meth administration. This occurs via restoration of the autophagy flux and, as assessed by ultrastructural morphometry, by preventing the dissipation of microtubule-associated protein 1 light chain 3 (LC3) from autophagy vacuoles to the cytosol, which is produced instead during Meth toxicity. These findings may have an impact in a variety of degenerative conditions characterized by NE deficiency along with autophagy impairment.

scholarly journals ApoE4 (Δ272–299) induces mitochondrial‐associated membrane formation and mitochondrial impairment by enhancing GRP75-modulated mitochondrial calcium overload in neuron

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tao Liang ◽  
Weijian Hang ◽  
Jiehui Chen ◽  
Yue Wu ◽  
Bin Wen ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Er Stress ◽  
Mitochondrial Dysfunction ◽  
Mitochondrial Function ◽  
Calcium Transport ◽  
Calcium Overload ◽  
Mitochondrial Calcium ◽  
Mitochondrial Impairment

Abstract Background Apolipoprotein E4 (apoE4) is a major genetic risk factor of Alzheimer’s disease. Its C-terminal-truncated apoE4 (Δ272–299) has neurotoxicity by affecting mitochondrial respiratory function. However, the molecular mechanism(s) underlying the action of apoE4 (Δ272–299) in mitochondrial function remain poorly understood. Methods The impact of neuronal apoE4 (Δ272–299) expression on ER stress, mitochondrial-associated membrane (MAM) formation, GRP75, calcium transport and mitochondrial impairment was determined in vivo and in vitro. Furthermore, the importance of ER stress or GRP75 activity in the apoE4 (Δ272–299)-promoted mitochondrial dysfunction in neuron was investigated. Results Neuronal apoE4 (Δ272–299) expression induced mitochondrial impairment by inducing ER stress and mitochondrial-associated membrane (MAM) formation in vivo and in vitro. Furthermore, apoE4 (Δ272–299) expression promoted GRP75 expression, mitochondrial dysfunction and calcium transport into the mitochondria in neuron, which were significantly mitigated by treatment with PBA (an inhibitor of ER stress), MKT077 (a specific GRP75 inhibitor) or GRP75 silencing. Conclusions ApoE4 (Δ272–299) significantly impaired neuron mitochondrial function by triggering ER stress, up-regulating GRP75 expression to increase MAM formation, and mitochondrial calcium overload. Our findings may provide new insights into the neurotoxicity of apoE4 (Δ272–299) against mitochondrial function and uncover new therapeutic targets for the intervention of Alzheimer’s disease.

scholarly journals Effects of cytoplasmic acidification on clathrin lattice morphology.

1989 ◽  
Vol 108 (2) ◽  
pp. 401-411 ◽  
Author(s):  
J Heuser
Keyword(s):  
Plasma Membrane ◽  
Cultured Cells ◽  
Membrane Receptors ◽  
The Other ◽  
Culture Dish ◽  
Initial Curvature ◽  
Internal Ph ◽  
Cytoplasmic Acidification

Reducing the internal pH of cultured cells by several different protocols that block endocytosis is found to alter the structure of clathrin lattices on the inside of the plasma membrane. Lattices curve inward until they become almost spherical yet remain stubbornly attached to the membrane. Also, the lattices bloom empty "microcages" of clathrin around their edges. Correspondingly, broken-open cells bathed in acidified media demonstrate similar changes in clathrin lattices. Acidification accentuates the normal tendency of lattices to round up in vitro and also stimulates them to nucleate microcage formation from pure solutions of clathrin. On the other hand, several conditions that also inhibit endocytosis have been found to create, instead of unusually curved clathrin lattices with extraneous microcages, a preponderance of unusually flat lattices. These treatments include pH-"clamping" cells at neutrality with nigericin, swelling cells with hypotonic media, and sticking cells to the surface of a culture dish with soluble polylysine. Again, the unusually flat lattices in such cells display a tendency to round up and to nucleate clathrin microcage formation during subsequent in vitro acidification. This indicates that regardless of the initial curvature of clathrin lattices, they all display an ability to grow and increase their curvature in vitro, and this is enhanced by lowering ambient pH. Possibly, clathrin lattice growth and curvature in vivo may also be stimulated by a local drop in pH around clusters of membrane receptors.

scholarly journals Purinergic Modulation of Interleukin-1β Release from Microglial Cells Stimulated with Bacterial Endotoxin

1997 ◽  
Vol 185 (3) ◽  
pp. 579-582 ◽  
Author(s):  
Davide Ferrari ◽  
Paola Chiozzi ◽  
Simonetta Falzoni ◽  
Stefania Hanau ◽  
Francesco Di  Virgilio
Keyword(s):  
Plasma Membrane ◽  
P2x7 Receptor ◽  
Purinergic Receptor ◽  
Present Report ◽  
Physiological Role ◽  
Bacterial Endotoxin ◽  
Microglial Cells

Microglial cells express a peculiar plasma membrane receptor for extracellular ATP, named P2Z/P2X7 purinergic receptor, that triggers massive transmembrane ion fluxes and a reversible permeabilization of the plasma membrane to hydrophylic molecules of up to 900 dalton molecule weight and eventual cell death (Di Virgilio, F. 1995. Immunol. Today. 16:524–528). The physiological role of this newly cloned (Surprenant, A., F. Rassendren, E. Kawashima, R.A. North and G. Buell. 1996. Science (Wash. DC). 272:735–737) cytolytic receptor is unknown. In vitro and in vivo activation of the macrophage and microglial cell P2Z/P2X7 receptor by exogenous ATP causes a large and rapid release of mature IL-1β. In the present report we investigated the role of microglial P2Z/P2X7 receptor in IL-1β release triggered by LPS. Our data suggest that LPS-dependent IL-1β release involves activation of this purinergic receptor as it is inhibited by the selective P2Z/P2X7 blocker oxidized ATP and modulated by ATP-hydrolyzing enzymes such as apyrase or hexokinase. Furthermore, microglial cells release ATP when stimulated with LPS. LPS-dependent release of ATP is also observed in monocyte-derived human macrophages. It is suggested that bacterial endotoxin activates an autocrine/paracrine loop that drives ATP-dependent IL-1β secretion.

scholarly journals Studies of insulin resistance in patients with clinical and subclinical hypothyroidism

2009 ◽  
Vol 160 (5) ◽  
pp. 785-790 ◽  
Author(s):  
Eirini Maratou ◽  
Dimitrios J Hadjidakis ◽  
Anastasios Kollias ◽  
Katerina Tsegka ◽  
Melpomeni Peppa ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Plasma Membrane ◽  
Glucose Transport ◽  
Subclinical Hypothyroidism ◽  
Tolerance Test ◽  
Oral Glucose ◽  
Model Assessment ◽  
Increased Risk

ObjectiveAlthough clinical hypothyroidism (HO) is associated with insulin resistance, there is no information on insulin action in subclinical hypothyroidism (SHO).Design and methodsTo investigate this, we assessed the sensitivity of glucose metabolism to insulin both in vivo (by an oral glucose tolerance test) and in vitro (by measuring insulin-stimulated rates of glucose transport in isolated monocytes with flow cytometry) in 21 euthyroid subjects (EU), 12 patients with HO, and 13 patients with SHO.ResultsAll three groups had comparable plasma glucose levels, with the HO and SHO having higher plasma insulin than the EU (P<0.05). Homeostasis model assessment index was increased in HO (1.97±0.22) and SHO (1.99±0.13) versus EU (1.27±0.16, P<0.05), while Matsuda index was decreased in HO (3.89±0.36) and SHO (4.26±0.48) versus EU (7.76±0.87, P<0.001), suggesting insulin resistance in both fasting and post-glucose state. At 100 μU/ml insulin: i) GLUT4 levels on the monocyte plasma membrane were decreased in both HO (215±19 mean fluorescence intensity, MFI) and SHO (218±24 MFI) versus EU (270±25 MFI, P=0.03 and 0.04 respectively), and ii) glucose transport rates in monocytes from HO (481±30 MFI) and SHO (462±19 MFI) were decreased versus EU (571±15 MFI, P=0.04 and 0.004 respectively).ConclusionsIn patients with HO and SHO: i) insulin resistance was comparable; ii) insulin-stimulated rates of glucose transport in isolated monocytes were decreased due to impaired translocation of GLUT4 glucose transporters on the plasma membrane; iii) these findings could justify the increased risk for insulin resistance-associated disorders, such as cardiovascular disease, observed in patients with HO or SHO.

scholarly journals Sphingosine 1-phosphate in inflammation

2020 ◽  
Vol 4 (6) ◽  
Author(s):  
Lijuan Li ◽  
Lixia An ◽  
Lifang Li ◽  
Yongjuan Zhao
Keyword(s):  
Plasma Membrane ◽  
Drug Targets ◽  
Therapeutic Potential ◽  
Cell Types ◽  
In Vivo Models ◽  
Integral Role ◽  
Sphingosine 1 Phosphate ◽  
And Migration

Sphingolipids are formed via the metabolism of sphingomyelin, aconstituent of the plasma membrane, or by denovosynthesis. Enzymatic pathways result in the formation of several different lipid mediators, which are known to have important roles in many cellular processes, including proliferation, apoptosis and migration. Several studies now suggest that these sphingolipid mediators, including ceramide, ceramide 1-phosphate and sphingosine 1-phosphate (S1P), are likely to have an integral role in in?ammation. This can involve, for example, activation of pro-in?ammatory transcription factors in different cell types and induction of cyclooxygenase-2, leading to production of pro-in?ammatory prostaglandins. The mode of action of each sphingolipid is different. Increased ceramide production leads to the formation of ceramide-rich areas of the membrane, which may assemble signalling complexes, whereas S1P acts via high-af?nity G-protein-coupled S1P receptors on the plasma membrane. Recent studies have demonstrated that in vitro effects of sphingolipids on in?ammation can translate into in vivo models. This review will highlight the areas of research where sphingolipids are involved in in?ammation and the mechanisms of action of each mediator. In addition, the therapeutic potential of drugs that alter sphingolipid actions will be examined with reference to disease states, such as asthma and in?ammatory bowel disease, which involve important in?ammatory components. A signi?cant body of research now indicates that sphingolipids are intimately involved in the in?ammatory process and recent studies have demonstrated that these lipids, together with associated enzymes and receptors, can provide effective drug targets for the treatment of pathological in?ammation.

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