scholarly journals Optical investigations reveal the effects of 2-aminoethyldiphenyl borate on STIM1 puncta formation

2018 ◽  
Vol 11 (02) ◽  
pp. 1850003 ◽  
Author(s):  
Tao Yu ◽  
Shangbin Chen ◽  
Jingying Pan ◽  
Conglin Su ◽  
Jun He
Keyword(s):  
Plasma Membrane ◽  
Inhibitory Action ◽  
Calcium Release ◽  
Confocal Imaging ◽  
Text Entry ◽  
Inhibitory Mechanism ◽  
Inhibitory Effects ◽  
Inhibition Effect ◽  
Imaging Results ◽  
And Function

2-Aminoethyldiphenyl borate (2-APB) is the most commonly used pharmacological agent in the study of calcium release-activated channels (CRACs); however, its inhibitory mechanism to CRACs remains unclear. To address this issue, we systematically employed confocal imaging, dual-wavelength excitation photometry and FRET to examine the effects of 2-APB on the dynamic activities and function of STIM1 and Orai1, two key components of CRACs. Imaging results support that there are two signaling pathways (Orai1-independent and Orai1-dependent) for the formation of STIM1 puncta. 2-APB could dose dependently block Orai1-independent but not Orai1-dependent STIM1 puncta formation, despite its obvious inhibition effect on store-operated Ca[Formula: see text] entry (SOCE). In addition, we found that although 2-APB could not visibly alter near plasma membrane CAD-eYFP localization, it could completely block CAD-YFP-induced constitutive Ca[Formula: see text] entry and promote the interaction between Orai1 and CAD by FRET measurements. Therefore, we proposed that inhibitory action of 2-APB on SOCE might attribute to its direct inhibitory effects on Orai1 channel itself, but not the interference on puncta formation between STIM1 and Orai1.

scholarly journals ANOs 3–7 in the anoctamin/Tmem16 Cl− channel family are intracellular proteins

2012 ◽  
Vol 302 (3) ◽  
pp. C482-C493 ◽  
Author(s):  
Charity Duran ◽  
Zhiqiang Qu ◽  
Adeboye O. Osunkoya ◽  
Yuanyuan Cui ◽  
H. Criss Hartzell
Keyword(s):  
Plasma Membrane ◽  
Fluid Transport ◽  
Neuronal Excitability ◽  
Family Members ◽  
Confocal Imaging ◽  
Sensory Transduction ◽  
Hek293 Cells ◽  
Whole Cell Patch Clamp ◽  
Intracellular Ca ◽  
And Function

Ca2+-activated Cl− channels (CaCCs) participate in numerous physiological functions such as neuronal excitability, sensory transduction, and transepithelial fluid transport. Recently, it was shown that heterologously expressed anoctamins ANO1 and ANO2 generate currents that resemble native CaCCs. The anoctamin family (also called Tmem16) consists of 10 members, but it is not known whether all members of the family are CaCCs. Expression of ANOs 3–7 in HEK293 cells did not generate Cl− currents activated by intracellular Ca2+, as determined by whole cell patch clamp electrophysiology. With the use of confocal imaging, only ANO1 and ANO2 traffic to the plasma membrane when expressed heterologously. Furthermore, endogenously expressed ANO7 in the human prostate is predominantly intracellular. We took a chimeric approach to identify regions critical for channel trafficking and function. However, none of the chimeras of ANO1 and ANO5/7 that we made trafficked to the plasma membrane. Our results suggest that intracellular anoctamins may be endoplasmic reticulum proteins, although it remains unknown whether these family members are CaCCs. Determining the role of anoctamin family members in ion transport will be critical to understanding their functions in physiology and disease.

scholarly journals The regulator of G protein signaling (RGS) domain of G protein–coupled receptor kinase 5 (GRK5) regulates plasma membrane localization and function

2014 ◽  
Vol 25 (13) ◽  
pp. 2105-2115 ◽  
Author(s):  
Hua Xu ◽  
Xiaoshan Jiang ◽  
Ke Shen ◽  
Christopher C. Fischer ◽  
Philip B. Wedegaertner
Keyword(s):  
Plasma Membrane ◽  
G Protein ◽  
Calcium Release ◽  
Membrane Localization ◽  
G Protein Signaling ◽  
Protein Signaling ◽  
G Protein Coupled Receptor ◽  
Rgs Domain ◽  
And Function ◽  
G Protein Coupled

The G protein–coupled receptor (GPCR) kinases (GRKs) phosphorylate activated GPCRs at the plasma membrane (PM). Here GRK5/GRK4 chimeras and point mutations in GRK5 identify a short sequence within the regulator of G protein signaling (RGS) domain in GRK5 that is critical for GRK5 PM localization. This region of the RGS domain of GRK5 coincides with a region of GRK6 and GRK1 shown to form a hydrophobic dimeric interface (HDI) in crystal structures. Coimmunoprecipitation (coIP) and acceptor photobleaching fluorescence resonance energy transfer assays show that expressed GRK5 self-associates in cells, whereas GRK5-M165E/F166E (GRK5-EE), containing hydrophilic mutations in the HDI region of the RGS domain, displays greatly decreased coIP interactions. Both forcing dimerization of GRK5-EE, via fusion to leucine zipper motifs, and appending an extra C-terminal membrane-binding region to GRK5-EE (GRK5-EE-CT) recover PM localization. In addition, GRK5-EE displays a decreased ability to inhibit PAR1-induced calcium release compared with GRK5 wild type (wt). In contrast, PM-localized GRK5-EE-CaaX (appending a C-terminal prenylation and polybasic motif from K-ras) or GRK5-EE-CT shows comparable ability to GRK5 wt to inhibit PAR1-induced calcium release. The results suggest a novel model in which GRK5 dimerization is important for its plasma membrane localization and function.

Inhibition of ADP-Induced Responses in Human Platelets by Agents Elevating the Cyclic AMP Level: Comparison of Aggregation and Shape Change

1984 ◽  
Vol 52 (03) ◽  
pp. 333-335 ◽  
Author(s):  
Vider M Steen ◽  
Holm Holmsen
Keyword(s):  
Inhibitory Action ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Inhibitory Effects ◽  
Early Step ◽  
Stimulus Response ◽  
Sequential Relationship

SummaryThe inhibitory effect of cAMP-elevating agents on shape change and aggregation in human platelets was studied to improve the understanding of the sequential relationship between these two responses.Human platelet-rich plasma was preincubated for 2 min at 37° C with prostaglandin E1 or adenosine, agents known to elevate the intracellular level of cAMP. Their inhibitory effects on ADP-induced shape change and aggregation were determined both separately and simultaneously. The dose-inhibition patterns for shape change and aggregation were similar for both PGE1 and adenosine. There was no distinct difference between the inhibitory action of these two inhibitors.These observations suggest that elevation of the intracellular concentration of cAMP interferes with an early step in the stimulus-response coupling that is common for aggregation and shape change.

scholarly journals Actin-membrane interaction in fibroblasts: what proteins are involved in this association?

1984 ◽  
Vol 99 (1) ◽  
pp. 95s-103s ◽  
Author(s):  
P Mangeat ◽  
K Burridge
Keyword(s):  
Plasma Membrane ◽  
Actin Filaments ◽  
Stress Fiber ◽  
Membrane Interaction ◽  
Microfilament Bundles ◽  
The Family ◽  
Form Part ◽  
Membrane Attachment ◽  
A Chain ◽  
And Function

In this review we discuss some of the proteins for which a role in linking actin to the fibroblast plasma membrane has been suggested. We focus on the family of proteins related to erythrocyte spectrin, proteins that have generally been viewed as having an organization and a function in actin-membrane attachment similar to those of erythrocyte spectrin. Experiments in which we precipitated the nonerythrocyte spectrin within living fibroblasts have led us to question this supposed similarity of organization and function of the nonerythrocyte and erythrocyte spectrins. Intracellular precipitation of fibroblast spectrin does not affect the integrity of the major actin-containing structures, the stress fiber microfilament bundles. Unexpectedly, however, we found that the precipitation of spectrin results in a condensation and altered distribution of the vimentin class of intermediate filaments in most cells examined. Although fibroblast spectrin may have a role in the attachment of some of the cortical, submembranous actin, it is surprising how little the intracellular immunoprecipitation of the spectrin affects the cells. Several proteins have been found concentrated at the ends of stress fibers, where the actin filaments terminate at focal contacts. Two of these proteins, alpha-actinin and fimbrin, have properties that suggest that they are not involved in the attachment of the ends of the bundles to the membrane but are more probably involved in the organization and cross-linking of the filaments within the bundles. On the other hand, vinculin and talin are two proteins that interact with each other and may form part of a chain of attachments between the ends of the microfilament bundles and the focal contact membrane. Their role in this attachment, however, has not been established and further work is needed to examine their interaction with actin and to identify any other components with which they may interact, particularly in the plasma membrane.

scholarly journals Impact of Membrane Lipids on UapA and AzgA Transporter Subcellular Localization and Activity in Aspergillus nidulans

2021 ◽  
Vol 7 (7) ◽  
pp. 514
Author(s):  
Mariangela Dionysopoulou ◽  
George Diallinas
Keyword(s):  
Plasma Membrane ◽  
Subcellular Localization ◽  
Aspergillus Nidulans ◽  
Membrane Lipids ◽  
Membrane Lipid ◽  
Lipid Biosynthesis ◽  
Transport Kinetics ◽  
Negative Effect ◽  
And Function

Recent biochemical and biophysical evidence have established that membrane lipids, namely phospholipids, sphingolipids and sterols, are critical for the function of eukaryotic plasma membrane transporters. Here, we study the effect of selected membrane lipid biosynthesis mutations and of the ergosterol-related antifungal itraconazole on the subcellular localization, stability and transport kinetics of two well-studied purine transporters, UapA and AzgA, in Aspergillus nidulans. We show that genetic reduction in biosynthesis of ergosterol, sphingolipids or phosphoinositides arrest A. nidulans growth after germling formation, but solely blocks in early steps of ergosterol (Erg11) or sphingolipid (BasA) synthesis have a negative effect on plasma membrane (PM) localization and stability of transporters before growth arrest. Surprisingly, the fraction of UapA or AzgA that reaches the PM in lipid biosynthesis mutants is shown to conserve normal apparent transport kinetics. We further show that turnover of UapA, which is the transporter mostly sensitive to membrane lipid content modification, occurs during its trafficking and by enhanced endocytosis, and is partly dependent on autophagy and Hect-type HulARsp5 ubiquitination. Our results point out that the role of specific membrane lipids on transporter biogenesis and function in vivo is complex, combinatorial and transporter-dependent.

scholarly journals Plasma membrane integrity in health and disease: significance and therapeutic potential

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Catarina Dias ◽  
Jesper Nylandsted
Keyword(s):  
Plasma Membrane ◽  
Therapeutic Potential ◽  
Calcium Influx ◽  
Membrane Integrity ◽  
Cell Types ◽  
Physical Parameters ◽  
Membrane Repair ◽  
Plasma Membrane Integrity ◽  
Repair Mechanisms ◽  
And Function

AbstractMaintenance of plasma membrane integrity is essential for normal cell viability and function. Thus, robust membrane repair mechanisms have evolved to counteract the eminent threat of a torn plasma membrane. Different repair mechanisms and the bio-physical parameters required for efficient repair are now emerging from different research groups. However, less is known about when these mechanisms come into play. This review focuses on the existence of membrane disruptions and repair mechanisms in both physiological and pathological conditions, and across multiple cell types, albeit to different degrees. Fundamentally, irrespective of the source of membrane disruption, aberrant calcium influx is the common stimulus that activates the membrane repair response. Inadequate repair responses can tip the balance between physiology and pathology, highlighting the significance of plasma membrane integrity. For example, an over-activated repair response can promote cancer invasion, while the inability to efficiently repair membrane can drive neurodegeneration and muscular dystrophies. The interdisciplinary view explored here emphasises the widespread potential of targeting plasma membrane repair mechanisms for therapeutic purposes.

scholarly journals Micro-analysis of pure deoxyribonucleic acid-dependent ribonucleic acid polymerase from Escherichia coli. Action of heparin and rifampicin on structure and function

1970 ◽  
Vol 117 (3) ◽  
pp. 623-631 ◽  
Author(s):  
Volker Neuhoff ◽  
Wolf-Bernhard Schill ◽  
Hans Sternbach
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
Rna Synthesis ◽  
Deoxyribonucleic Acid ◽  
Structure And Function ◽  
Disc Electrophoresis ◽  
Inhibitory Mechanism ◽  
And Function ◽  
Micro Analysis ◽  
Template Complex

By using micro disc electrophoresis and micro-diffusion techniques, the interaction of pure DNA-dependent RNA polymerase (EC 2.7.7.6) from Escherichia coli with the template, the substrates and the inhibitors heparin and rifampicin was investigated. The following findings were obtained: (1) heparin converts the 24S and 18S particles of the polymerase into the 13S form; (2) heparin inhibits RNA synthesis by dissociating the enzyme–template complex; (3) rifampicin does not affect the attachment of heparin to the enzyme; (4) the substrates ATP and UTP are bound by enzyme loaded with rifampicin; (5) rifampicin is bound by an enzyme–template complex to the same extent as by an RNA-synthesizing enzyme–template complex. From this it is concluded that the mechanism of the inhibition of RNA synthesis by rifampicin is radically different from that by heparin. As a working hypothesis to explain the inhibitory mechanism of rifampicin, it is assumed that it becomes very firmly attached to a position close to the synthesizing site and only blocks this when no synthesis is in progress.

scholarly journals Expression and Function of Thyroid Hormone Transporters in the Microvillous Plasma Membrane of Human Term Placental Syncytiotrophoblast

Endocrinology ◽  
2012 ◽  
Vol 153 (12) ◽  
pp. 6126-6135 ◽  
Author(s):  
L. S. Loubière ◽  
E. Vasilopoulou ◽  
J. D. Glazier ◽  
P. M. Taylor ◽  
J. A. Franklyn ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Thyroid Hormone ◽  
And Function

Abstract MP216: Identification Of Novel Phosphoprotein Signaling Pathways In Human Dilated Cardiomyopathy By Integrative Proteomic And Phosphoproteomic Analysis

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Cristine J Reitz ◽  
Marjan Tavassoli ◽  
Da Hye Kim ◽  
Sina Hadipour-Lakmehsari ◽  
Saumya Shah ◽  
...  
Keyword(s):  
Dilated Cardiomyopathy ◽  
Cardiac Tissue ◽  
Regulatory Element ◽  
Critical Role ◽  
Left Ventricular ◽  
Confocal Imaging ◽  
Intercalated Disc ◽  
Bioinformatics Analyses ◽  
Tissue Samples ◽  
And Function

Dilated cardiomyopathy (DCM) is one of the most common causes of heart failure, yet the majority of the underlying signaling mechanisms remain poorly characterized. Protein phosphorylation is a key regulatory element with profound effects on the activity and function of signaling networks; however, there is a lack of comprehensive phosphoproteomic studies in human DCM patients. We assessed the hypothesis that an integrative phosphoproteomics analysis of human DCM would reveal novel phosphoprotein candidates involved in disease pathophysiology. Combined proteomic and phosphoproteomic analysis of explanted left ventricular tissue samples from DCM patients ( n =4) and non-failing controls ( n =4) identified 5,570 unique proteins with 13,624 corresponding phosphorylation sites. From these analyses, we identified αT-catenin as a unique candidate protein with a cluster of 4 significantly hyperphosphorylated sites in DCM hearts ( P <0.0001), with no change in total αT-catenin expression at the protein level. Bioinformatics analyses of human datasets and confocal imaging of human and mouse cardiac tissue show highly cardiac-enriched expression of αT-catenin, localized to the cardiomyocyte intercalated disc. High resolution 3-dimensional reconstruction shows elongated intercalated disc morphology in DCM hearts (10.07±0.76 μm in controls vs. 17.20±1.87 μm in DCM, P <0.05, n =3/group), with significantly increased colocalization of αT-catenin with the intercalated disc membrane protein N-cadherin (Pearson’s coefficient 0.55±0.04 in controls vs. 0.71±0.02 in DCM, P <0.05, n =3/group). To investigate the functional role of cardiac αT-catenin phosphorylation, we overexpressed WT protein vs. non-phosphorylatable forms based on the loci identified in DCM hearts, in adult mouse cardiomyocytes using lentiviral transduction. Confocal imaging revealed significant internalization of the phospho-null form, as compared to the prominent intercalated disc staining of the WT protein (17.78±0.79% of WT vs. 9.25±0.49% of 4A mutant, P <0.0001, n =50 cells/group). Together, these findings suggest a critical role for αT-catenin phosphorylation in maintaining cardiac intercalated disc organization in human DCM.

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