Stabilization of Endothelial Receptor Arrays by a Polarized Spectrin Cytoskeleton Facilitates Rolling Adhesion of Leukocytes

2020 ◽  
Author(s):  
Sivakami Mylvaganam ◽  
Magdalena Riedl ◽  
Anthony Vega ◽  
Richard F. Collins ◽  
Khuloud Jaqaman ◽  
...  
Keyword(s):  
Spectrin Cytoskeleton ◽  
Endothelial Receptor

scholarly journals Stabilization of Endothelial Receptor Arrays by a Polarized Spectrin Cytoskeleton Facilitates Rolling and Adhesion of Leukocytes

Cell Reports ◽  
2020 ◽  
Vol 31 (12) ◽  
pp. 107798 ◽  
Author(s):  
Sivakami Mylvaganam ◽  
Magdalena Riedl ◽  
Anthony Vega ◽  
Richard F. Collins ◽  
Khuloud Jaqaman ◽  
...  
Keyword(s):  
Spectrin Cytoskeleton ◽  
Endothelial Receptor

scholarly journals Contractile and Endothelium-Dependent Dilatory Responses of Cerebral Arteries at Various Extracellular Magnesium Concentrations

1991 ◽  
Vol 11 (1) ◽  
pp. 161-164 ◽  
Author(s):  
Mária Faragó ◽  
Csaba Szabó ◽  
Eörs Dóra ◽  
Ildikó Horváth ◽  
Arisztid G. B. Kovách
Keyword(s):  
Smooth Muscle ◽  
Vascular Reactivity ◽  
Calcium Influx ◽  
Cerebral Arteries ◽  
Inhibitory Effect ◽  
Contractile Responses ◽  
Middle Cerebral Arteries ◽  
The Right ◽  
Endothelial Receptor

To clarify the effect of extracellular magnesium (Mg2+) on the vascular reactivity of feline isolated middle cerebral arteries, the effects of slight alterations in the Mg2+ concentration on the contractile and endothelium-dependent dilatory responses were investigated in vitro. The contractions, induced by 10−8-10−5 M norepinephrine, were significantly potentiated at low Mg2+ (0.8 m M v. the normal, 1.2 m M). High (1.6 and 2.0 m M) Mg2+ exhibited an inhibitory effect on the contractile responses. No significant changes, however, in the EC50 values for norepinephrine were found. The endothelium-dependent relaxations induced by 108–10−5 M acetylcholine were inhibited by high (1.6 and 2.0 m M) Mg2+. Lowering of the Mg2+ concentration to 0.8 m M or total withdrawal of this ion from the medium failed to alter the dilatory potency of acetylcholine. The changes in the dilatory responses also shifted the EC50 values for acetylcholine to the right. The present results show that the contractile responses of the cerebral arteries are extremely susceptible to the changes of Mg2+ concentrations. In response to contractile and endothelium-dependent dilatory agonists, Mg2+ probably affects both the calcium influx into the endothelial and smooth muscle cells as well as the binding of acetylcholine to its endothelial receptor. Since Mg2+ deficiency might facilitate the contractile but not the endothelium-dependent relaxant responses, the present study supports a role for Mg2+ deficiency in the development of the cerebral vasospasm.

scholarly journals Solubility of cytoskeletal proteins in immunohistochemistry and the influence of fixation.

1993 ◽  
Vol 41 (4) ◽  
pp. 609-616 ◽  
Author(s):  
B M Riederer ◽  
R Porchet ◽  
R A Marugg ◽  
L I Binder
Keyword(s):  
Protein Solubility ◽  
Immunohistochemical Localization ◽  
Influential Factors ◽  
Cytoskeletal Proteins ◽  
Fixed Tissue ◽  
Aldehyde Fixation ◽  
Cat Brain ◽  
Spectrin Cytoskeleton ◽  
Cryostat Sections

For accurate and quantitative immunohistochemical localization of antigens it is crucial to know the solubility of tissue proteins and their degree of loss during processing. In this study we focused on the solubility of several cytoskeletal proteins in cat brain tissue at various ages and their loss during immunohistochemical procedures. We further examined whether fixation affected either solubility or immunocytochemical detectability of several cytoskeletal proteins. An assay was designed to measure the solubility of cytoskeletal proteins in cryostat sections. Quantity and quality of proteins lost or remaining in tissue were measured and analyzed by electrophoresis and immunoblots. Most microtubule proteins were found to be soluble in unfixed and alcohol fixed tissues. Furthermore, the microtubule proteins remaining in the tissue had a changed cellular distribution. In contrast, brain spectrin and all three neurofilament subunits were insoluble and remained in the tissue, allowing their immunocytochemical localization in alcohol-fixed tissue. Synapsin I, a protein associated with the spectrin cytoskeleton, was soluble, and aldehyde fixation is advised for its immunohistochemical localization. With aldehyde fixation, the immunoreactivity of some antibodies against neurofilament proteins was reduced in axons unveiling novel immunogenic sites in nuclei that may represent artifacts of fixation. In conclusion, protein solubility and the effects of fixation are influential factors in cytoskeletal immunohistochemistry, and should be considered before assessments for a quantitative distribution are made.

scholarly journals Targeting spectrin redox switches to regulate the mechanoproperties of red blood cells

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Frederik Barbarino ◽  
Lucas Wäschenbach ◽  
Virginia Cavalho-Lemos ◽  
Melissa Dillenberger ◽  
Katja Becker ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Redox Regulation ◽  
Current Knowledge ◽  
Structural Characteristics ◽  
Functional Characterization ◽  
Physiological Role ◽  
Spectrin Cytoskeleton ◽  
Redox Switches

AbstractThe mechanical properties of red blood cells (RBCs) are fundamental for their physiological role as gas transporters. RBC flexibility and elasticity allow them to survive the hemodynamic changes in the different regions of the vascular tree, to dynamically contribute to the flow thereby decreasing vascular resistance, and to deform during the passage through narrower vessels. RBC mechanoproperties are conferred mainly by the structural characteristics of their cytoskeleton, which consists predominantly of a spectrin scaffold connected to the membrane via nodes of actin, ankyrin and adducin. Changes in redox state and treatment with thiol-targeting molecules decrease the deformability of RBCs and affect the structure and stability of the spectrin cytoskeleton, indicating that the spectrin cytoskeleton may contain redox switches. In this perspective review, we revise current knowledge about the structural and functional characterization of spectrin cysteine redox switches and discuss the current lines of research aiming to understand the role of redox regulation on RBC mechanical properties. These studies may provide novel functional targets to modulate RBC function, blood viscosity and flow, and tissue perfusion in disease conditions.

scholarly journals Apical, Lateral, and Basal Polarization Cues Contribute to the Development of the Follicular Epithelium during Drosophila Oogenesis

2000 ◽  
Vol 151 (4) ◽  
pp. 891-904 ◽  
Author(s):  
Guy Tanentzapf ◽  
Christian Smith ◽  
Jane McGlade ◽  
Ulrich Tepass
Keyword(s):  
Apical Membrane ◽  
Pdz Domain ◽  
Basal Membrane ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Epithelial Surface ◽  
Mosaic Analysis ◽  
Spectrin Cytoskeleton ◽  
Surface Domains ◽  
Mesenchymal Epithelial Transition

Analysis of the mechanisms that control epithelial polarization has revealed that cues for polarization are mediated by transmembrane proteins that operate at the apical, lateral, or basal surface of epithelial cells. Whereas for any given epithelial cell type only one or two polarization systems have been identified to date, we report here that the follicular epithelium in Drosophila ovaries uses three different polarization mechanisms, each operating at one of the three main epithelial surface domains. The follicular epithelium arises through a mesenchymal–epithelial transition. Contact with the basement membrane provides an initial polarization cue that leads to the formation of a basal membrane domain. Moreover, we use mosaic analysis to show that Crumbs (Crb) is required for the formation and maintenance of the follicular epithelium. Crb localizes to the apical membrane of follicle cells that is in contact with germline cells. Contact to the germline is required for the accumulation of Crb in follicle cells. Discs Lost (Dlt), a cytoplasmic PDZ domain protein that was shown to interact with the cytoplasmic tail of Crb, overlaps precisely in its distribution with Crb, as shown by immunoelectron microscopy. Crb localization depends on Dlt, whereas Dlt uses Crb-dependent and -independent mechanisms for apical targeting. Finally, we show that the cadherin–catenin complex is not required for the formation of the follicular epithelium, but only for its maintenance. Loss of cadherin-based adherens junctions caused by armadillo (β-catenin) mutations results in a disruption of the lateral spectrin and actin cytoskeleton. Also Crb and the apical spectrin cytoskeleton are lost from armadillo mutant follicle cells. Together with previous data showing that Crb is required for the formation of a zonula adherens, these findings indicate a mutual dependency of apical and lateral polarization mechanisms.

scholarly journals In vivo behavior of human radioiodinated antithrombin III: distribution among three physiologic pools

Blood ◽  
1985 ◽  
Vol 66 (1) ◽  
pp. 13-19 ◽  
Author(s):  
TH Carlson ◽  
TL Simon ◽  
AC Atencio
Keyword(s):  
Endothelial Cell ◽  
Antithrombin Iii ◽  
Young Men ◽  
Fractional Catabolic Rate ◽  
Kinetic Behavior ◽  
Exponential Curve ◽  
Catabolic Rate ◽  
Total Body ◽  
Endothelial Receptor

Abstract It has recently been shown that antithrombin III (AT) distributes between plasma, a noncirculating vascular-associated pool and an extravascular pool in rabbit. Study of the in vivo behavior of autologous human 131I-AT demonstrates that in humans AT also distributes among three pools that are analogous to those found in rabbit. From the in vivo kinetic behavior of the 131I-labeled AT, the fractions of total-body AT in the plasma, noncirculating vascular- associated, and extravascular pools were calculated to be 0.393 +/- 0.015, 0.109 +/- 0.016, and 0.496 +/- 0.014, respectively. From three- exponential plasma radioactivity disappearance curves, an average plasma fractional catabolic rate, j3, of 0.576 +/- 0.034 day-1 was obtained for five healthy young men. This is almost identical to the result obtained if plasma 131I-AT disappearance is assumed to fit a two- exponential curve (0.546 +/- 0.038), where the constant C2 from *Ap(t) = C1e-a1t + C2e-a2t is assumed to be equal to 1 - C1. The fraction of the total vascular AT catabolized daily, j3.5, was calculated to be 0.457 +/- 0.034, and the fractional catabolic rate of total-body AT, jT, averaged 0.2271 +/- 0.0176. The results give further support to a model of in vivo behavior in which the vascular AT distributes between plasma and an endothelial receptor. Thus, the latter may serve to mediate activation of AT for its reaction with coagulation proteases and to mediate its entrance into the endothelial cell, where it is either transported to the extravascular fluids or is catabolized.

scholarly journals Dynein acts to cluster glutamate receptors and traffic the PIP5 kinase, Skittles, to regulate postsynaptic membrane organization at the neuromuscular junction

2021 ◽  
Author(s):  
Amanda L. Neisch ◽  
Thomas Pengo ◽  
Adam W. Avery ◽  
Min-Gang Li ◽  
Thomas S. Hays
Keyword(s):  
Neuromuscular Junctions ◽  
Cytoplasmic Dynein ◽  
Postsynaptic Membrane ◽  
Independent Function ◽  
Protein Levels ◽  
Cluster Organization ◽  
Synaptic Terminals ◽  
Cargo Transport ◽  
Spectrin Cytoskeleton ◽  
Phosphatidylinositol 4

Cytoplasmic dynein is essential in motoneurons for retrograde cargo transport that sustains neuronal connectivity. Little, however, is known about dynein's function on the postsynaptic side of the circuit. Here we report distinct postsynaptic roles for dynein at neuromuscular junctions (NMJs). Intriguingly, we show that dynein punctae accumulate postsynaptically at glutamatergic synaptic terminals. Moreover, Skittles, a phosphatidylinositol 4-phosphate 5-kinase that produces PI(4,5)P2 to organize the spectrin cytoskeleton, also localizes specifically to glutamatergic synaptic terminals. Depletion of postsynaptic dynein disrupts the accumulation of Skittles, PI(4,5)P2 phospholipid, and organization of the spectrin cytoskeleton at the postsynaptic membrane. Coincidental with dynein depletion, we observe an increase in the clusters size of ionotropic glutamate receptor (iGluR), and an increase in the amplitude and frequency of mEJPs. However, PI(4,5)P2 levels do not affect iGluR clustering and dynein does not affect the protein levels of iGluR subunits at the NMJ, suggesting a separate, transport independent function for dynein in iGluR cluster organization. As dynein punctae closely associate with iGluR clusters, we propose that dynein physically tethers iGluR clusters at the postsynaptic membrane to ensure proper synaptic transmission.

130 Characterization of a novel endothelial receptor, LR3, that defines a new class of receptors related to the LDL receptor family

1997 ◽  
Vol 11 ◽  
pp. 37
Author(s):  
Todd A. Hembrough ◽  
Frances D. Battey ◽  
Jeffrey A. Winkles ◽  
Dudley K. Strickland
Keyword(s):  
Ldl Receptor ◽  
New Class ◽  
Endothelial Receptor ◽  
Receptor Family
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