scholarly journals Purines as Transmitter Molecules: Electrophysiological Studies on Purinergic Signalling in Different Cell Systems

2009 ◽  
Author(s):  
Elisabetta Coppi
Keyword(s):  
Cell Signalling ◽  
Human Mesenchymal Stem Cells ◽  
Membrane Receptors ◽  
Receptor Expression ◽  
Purinergic Signalling ◽  
Cell Systems ◽  
Cellular Processes ◽  
Electrophysiological Studies ◽  
And Function

Purinergic nucleotides and nucleosides (ATP, ADP, AMP and adenosine) are essential intracellular metabolites involved in a number of cellular processes, from energy supply to protein phosphorylation. However, in the last years, several studies demonstrated their involvement in cell signalling by the activation of specific membrane receptors (P1 and P2) and their role as neurotransmitters began to be investigated. The present work was aimed to clarify the effects of purinergic neurotransmission in different cell systems by using electrophysiological techniques. Relevant results of this research include the observation that P1 and P2 receptors play a deleterious role during "in vitro" ischemia in the rat brain, and the first demonstration of P2 receptor expression and function in a line of adult human mesenchymal stem cells.

Role of the 807 C/T Polymorphism of the α2 Gene in Platelet GP Ia Collagen Receptor Expression and Function

1999 ◽  
Vol 81 (06) ◽  
pp. 951-956 ◽  
Author(s):  
J. Corral ◽  
R. González-Conejero ◽  
J. Rivera ◽  
F. Ortuño ◽  
P. Aparicio ◽  
...  
Keyword(s):  
Venous Thrombosis ◽  
Cell Types ◽  
Receptor Expression ◽  
Case Control Studies ◽  
Platelet Surface ◽  
Vitro Analysis ◽  
And Function ◽  
In Vitro Analysis

SummaryThe variability of the platelet GP Ia/IIa density has been associated with the 807 C/T polymorphism (Phe 224) of the GP Ia gene in American Caucasian population. We have investigated the genotype and allelic frequencies of this polymorphism in Spanish Caucasians. The T allele was found in 35% of the 284 blood donors analyzed. We confirmed in 159 healthy subjects a significant association between the 807 C/T polymorphism and the platelet GP Ia density. The T allele correlated with high number of GP Ia molecules on platelet surface. In addition, we observed a similar association of this polymorphism with the expression of this protein in other blood cell types. The platelet responsiveness to collagen was determined by “in vitro” analysis of the platelet activation and aggregation response. We found no significant differences in these functional platelet parameters according to the 807 C/T genotype. Finally, results from 3 case/control studies involving 302 consecutive patients (101 with coronary heart disease, 104 with cerebrovascular disease and 97 with deep venous thrombosis) determined that the 807 C/T polymorphism of the GP Ia gene does not represent a risk factor for arterial or venous thrombosis.

scholarly journals Design of self-assembling transmembrane helical bundles to elucidate principles required for membrane protein folding and ion transport

2017 ◽  
Vol 372 (1726) ◽  
pp. 20160214 ◽  
Author(s):  
Nathan H. Joh ◽  
Gevorg Grigoryan ◽  
Yibing Wu ◽  
William F. DeGrado
Keyword(s):  
Protein Folding ◽  
Membrane Protein ◽  
Protein Design ◽  
De Novo ◽  
Cell Signalling ◽  
Membrane Protein Folding ◽  
Cellular Processes ◽  
Membrane Pores ◽  
Self Assembling ◽  
And Function

Ion transporters and channels are able to identify and act on specific substrates among myriads of ions and molecules critical to cellular processes, such as homeostasis, cell signalling, nutrient influx and drug efflux. Recently, we designed Rocker, a minimalist model for Zn 2+ /H + co-transport. The success of this effort suggests that de novo membrane protein design has now come of age so as to serve a key approach towards probing the determinants of membrane protein folding, assembly and function. Here, we review general principles that can be used to design membrane proteins, with particular reference to helical assemblies with transport function. We also provide new functional and NMR data that probe the dynamic mechanism of conduction through Rocker. This article is part of the themed issue ‘Membrane pores: from structure and assembly, to medicine and technology’.

Human mesenchymal stem cells inhibit differentiation and function of monocyte-derived dendritic cells

Blood ◽  
2005 ◽  
Vol 105 (10) ◽  
pp. 4120-4126 ◽  
Author(s):  
Xiao-Xia Jiang ◽  
Yi Zhang ◽  
Bing Liu ◽  
Shuang-Xi Zhang ◽  
Ying Wu ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Dendritic Cells ◽  
Human Mesenchymal Stem Cells ◽  
Interleukin 4 ◽  
Human Mscs ◽  
Gm Csf ◽  
Macrophage Colony ◽  
And Function

AbstractMesenchymal stem cells (MSCs), in addition to their multilineage differentiation, have a direct immunosuppressive effect on T-cell proliferation in vitro. However, it is unclear whether they also modulate the immune system by acting on the very first step. In this investigation, we addressed the effects of human MSCs on the differentiation, maturation, and function of dendritic cells (DCs) derived from CD14+ monocytes in vitro. Upon induction with granulocyte-macrophage colony-stimulating factor (GM-CSF) plus interleukin-4 (IL-4), MSC coculture could strongly inhibit the initial differentiation of monocytes to DCs, but this effect is reversible. In particular, such suppression could be recapitulated with no intercellular contact at a higher MSC/monocyte ratio (1:10). Furthermore, mature DCs treated with MSCs were significantly reduced in the expression of CD83, suggesting their skew to immature status. Meanwhile, decreased expression of presentation molecules (HLA-DR and CD1a) and costimulatory molecules (CD80 and CD86) and down-regulated IL-12 secretion were also observed. In consistence, the allostimulatory ability of MSC-treated mature DCs on allogeneic T cells was impaired. In conclusion, our data suggested for the first time that human MSCs could suppress monocyte differentiation into DCs, the most potent antigen-presenting cells (APCs), thus indicating the versatile regulation of MSCs on the ultimate specific immune response.

scholarly journals DIFFERENTIATED EFFECTS OF GLUCOSAMINYLMURAMILDIPEPTIDE ON THE NONTRANSFORMED AND EXPERIMENTALLY TRANSFORMED PHENOTYPE OF CD62L+CD63+CD66d+ NEUTROPHILIC GRANULOCYTES IN CONVENTIONALLY HEALTHY PEOPLE

2018 ◽  
Vol 20 (6) ◽  
pp. 847-854
Author(s):  
I. V. Nesterova ◽  
V. V. Malinovskaya ◽  
S. V. Khaydukov ◽  
D. L. Nguyen Thi ◽  
G. A. Chudilova ◽  
...  
Keyword(s):  
Healthy Subjects ◽  
Inflammatory Diseases ◽  
Phenotypic Diversity ◽  
Membrane Receptors ◽  
Receptor Expression ◽  
Healthy People ◽  
High Plasticity ◽  
Neutrophilic Granulocytes ◽  
Cd63 Expression

Modern studies have shown a high plasticity and phenotypic diversity of neutrophilic granulocytes (NG) provided by different receptors, which are diagnostic markers for the functional capacity of the cell in the course of their activities. We investigated NG from peripheral  blood, obtained from healthy people of both sexes aged from 26 to 66 years. Evaluation of the neutrophil membrane receptor expression was carried out by flow cytometry. The relative amount of neutrophilic granulocytes expressing membrane CD62L, CD63, CD66d receptors and the intensity of their expression were  determined according to their fluorescence intensities. The surface NG membrane receptors, i.e., CD62L, CD63, CD66d were studied upon the in vitro experimental influence of the following bacterial peptides: N-formyl-methionyl-leucyl-phenylalanine (FMLP, model 1); glucosaminylmuramyldipeptide (GMDP, model 2), and simultaneous incubation of NG blood with fMLP and GMDP (model 3). The in vitro treatment with fMLP in the in vitro model was used to transform the NG phenotype of conventionally healthy subjects, expressing CD62, CD63, CD66d molecules. The treatment caused a significantly decrease in both CD62L and the CD62L expression in relative amounts of neutrophilic granulocytes with a parallel increase of CD63 expression density. The effect of GMDP on the NG phenotype of conditionally healthy subjects did not change the amount of CD62L+NG and CD63+NG, and did not affect CD62L and CD63 expression density on the surface of NG. However, the amount of CD66d+NG was significantly increased with the unchanged expression of CD66d molecules. GMDP introduced together with the bacterial fMLP peptide was shown to neutralize some features of the NG phenotype transformation caused by fMLP, i.e., the amount of CD62L+ NG was restored by 22 % and the CD62L expression density increased significantly. At the same time, GMDP did not correct the negative effect of fMLP upon the number of CD63+NG and CD66d+NG, and on the CD63 and CD66d expression. Simultaneous addition of fMLP  and GMDP did significantly increase the amount of CD66d+NG and expression density of CD63 molecules on the CD63+NG membrane as compared to intact NG of conditionally healthy subjects. The obtained data are important in order to justify some new immunotherapeutic strategies aimed at correction of the negatively transformed NG phenotype, which accompanies some infectious and inflammatory diseases of bacterial etiology with atypical clinical course. 

scholarly journals Histamine H2 receptor radioligands: triumphs and challenges

2021 ◽  
Author(s):  
Steffen Pockes ◽  
Katharina Tropmann
Keyword(s):  
Receptor Expression ◽  
In Vitro Assays ◽  
Histamine H2 Receptor ◽  
Drug Candidates ◽  
Carbon 14 ◽  
The Central Nervous System ◽  
And Function ◽  
Role And Function

Since the discovery of the histamine H2 receptor (H2R), radioligands were among the most powerful tools to investigate its role and function. Initially, radiolabeling was used to investigate human and rodent tissues regarding their receptor expression. Later, radioligands gained increasing significance as pharmacological tools in in vitro assays. Although tritium-labeling was mainly used for this purpose, labeling with carbon-14 is preferred for metabolic studies of drug candidates. After the more-or-less successful application of numerous labeled H2R antagonists, the recent development of the G protein-biased radioligand [3H]UR-KAT479 represents another step forward to elucidate the widely unknown role of the H2R in the central nervous system through future studies.

scholarly journals Scl-Ab reverts pro-osteoclastogenic signalling and resorption in estrogen deficient osteocytes 

2020 ◽  
Author(s):  
Hollie Allison ◽  
Gill Holdsworth ◽  
Laoise M McNamara
Keyword(s):  
Bone Resorption ◽  
Animal Studies ◽  
Cell Signalling ◽  
Osteoclast Differentiation ◽  
Estrogen Deficiency ◽  
Decrease Bone Resorption ◽  
And Function ◽  
Sclerostin Antibody

Abstract Neutralising antibodies to sclerostin (Scl-Ab) have shown significant potential to induce bone formation and decrease bone resorption, increase strength and substantially reduce fracture risk in animal studies and clinical trials. Mechanical loading negatively regulates sclerostin expression, and sclerostin has been shown to induce RANKL synthesis in osteocytes. However, how Scl-Ab governs osteocyte regulation of osteoclast differentiation and function is not fully understood. We have recently discovered that osteoblasts and osteocytes alter osteoclastogenic signalling (RANKL/OPG) during estrogen-deficiency, and that osteoblast-induced osteoclastogenesis and resorption are exacerbated. However, it is not known whether estrogen deficient osteocytes exhibit exacerbate osteoclastogenesis. The aims of this study were to (1) establish whether osteocytes induce osteoclastogenesis and bone resorption during estrogen deficiency in vitro (2) investigate whether the sclerostin antibody can revert osteocyte-mediated osteoclastogenesis and resorption by attenuating RANKL/OPG expression.Results Using conditioned media and co-culture experiments we found increased osteocyte-induced osteoclastogenesis and bone resorption in estrogen deficient conditions. This is the first study to report that administration of Scl-Ab has the ability to revert osteocyte-mediated osteoclastogenesis and resorption by decreasing RANKL/OPG ratio expression and increasing WISP1 expression in estrogen deficient osteocytes. ConclusionsThis study provides an enhanced understanding of the biological changes underpinning decreases in bone resorption following Scl-Ab treatment observed in vivo by revealing that Scl-Ab can reduce pro-osteoclastogenic cell signalling between osteocytes and osteoclasts.

scholarly journals Label-free methods for optical in vitro characterization of protein–protein interactions

2021 ◽  
Author(s):  
Fabian Soltermann ◽  
Weston B. Struwe ◽  
Philipp Kukura
Keyword(s):  
Protein Interactions ◽  
Label Free ◽  
Protein Protein Interactions ◽  
Cellular Processes ◽  
P Protein ◽  
In Vitro Characterization ◽  
And Function

Protein–protein interactions are involved in the regulation and function of the majority of cellular processes.

Abstract 281: Long-term Exposure of PM2.5 Causes Hypertension by Impaired Renal D1 Receptor Mediated Sodium Excretion via Up-regulation of GRK4 Expression in SD rats

Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Xi Lu ◽  
Ken Chen ◽  
Jing Zeng ◽  
Hongmei Ren ◽  
Chunyu Zeng
Keyword(s):  
Sodium Excretion ◽  
D1 Receptor ◽  
Receptor Expression ◽  
Sd Rats ◽  
Induced Hypertension ◽  
Pm2.5 Exposure ◽  
And Function

Introduction: Epidemiological evidence supports an important association between PM2.5 exposure and hypertension. There are reports that PM2.5 induced hypertension with impaired sodium excretion, however, the mechanisms are not clear. Hypothesis: We hypothesize that PM2.5, via increased ROS levels, increased GRK4 expression, consequently impaired renal D1 receptor function, and lead to hypertension. Methods: We used Sprague-Dawley (SD) rats with in-vivo PM2.5 exposure, and immortalized renal proximal tubule (RPT) cells from Wistar-Kyoto (WKY) rats in-vitro, which behave similarly to freshly obtained RPT cells. Results: Our present study found that long-term exposure of PM2.5 caused hypertension and impaired renal sodium excretion, which might be ascribed to lower D1 receptor expression and higher D1 receptor phosphorylation, accompanied with higher GRK4 expression. The in-vivo results were confirmed in in-vitro study, i.e. PM2.5 increased basal Na+-K+ ATPase activity, decreased D1 receptor mediated inhibitory effect on Na+-K+ ATPase activity, decreased D1 receptor expression and increased D1 receptor phosphorylation in RPT cells. The downregulation of D1 receptor expression and function might be due to higher GRK4 expression, because down-regulation of GRK4 by siRNA reversed the D1 receptor expression and function. Due to the role of ROS on D1 receptor dysfunction, we checked ROS levels, and found plasma ROS levels were higher in PM2.5 treated SD rats. Inhibition of ROS by tempol reduced blood pressure and increased sodium excretion in PM2.5 treated SD rats, accompanied by increased the lower D1 receptor expression, and decreased the hyperphosphorylated D1 receptor and GRK4 expression. Conclusions: Long-term exposure of PM2.5 increases blood pressure by decreased D1 receptor expression and function; ROS, via regulation of GRK4 expression, is taken part in the pathogenesis of PM2.5-induced hypertension.

The role of fatty acids in oocyte and early embryo development

2012 ◽  
Vol 24 (1) ◽  
pp. 59 ◽  
Author(s):  
Paul J. McKeegan ◽  
Roger G. Sturmey
Keyword(s):  
Fatty Acids ◽  
Cell Signalling ◽  
Early Embryo ◽  
Membrane Composition ◽  
Ongoing Research ◽  
Cellular Processes ◽  
Metabolic Functions ◽  
Human Fertility ◽  
Early Embryos

Growing evidence suggests that endogenous and exogenous fatty acids play diverse roles in developing mammalian oocytes and early embryos. In this review, we describe some of the regulatory roles of fatty acids in early development, in addition to their metabolic functions. We focus initially on the provision of individual fatty acids, and then discuss how these might affect metabolism, oxidative stress, membrane composition, cell signalling events and gene expression. We propose that ongoing research should focus on physiologically relevant ratios and combinations of fatty acids, rather than isolated individual fatty acids, as their combined roles are both subtle and complex. Changing the ratio of specific fatty acids in the diet of animal models, and in vitro culture medium can cause significant dysregulation of cellular processes and development, an issue that extends to human fertility.

scholarly journals Dopamine Receptor Expression and Function in Clinically Nonfunctioning Pituitary Tumors: Comparison with the Effectiveness of Cabergoline Treatment

2004 ◽  
Vol 89 (4) ◽  
pp. 1674-1683 ◽  
Author(s):  
Rosario Pivonello ◽  
Carmela Matrone ◽  
Mariagiovanna Filippella ◽  
Luigi M. Cavallo ◽  
Carolina Di Somma ◽  
...  
Keyword(s):  
Dopamine Receptor ◽  
D2 Receptor ◽  
Pituitary Tumors ◽  
Receptor Expression ◽  
Treatment Schedule ◽  
Α Subunit ◽  
Tumor Mass ◽  
Isoform Expression ◽  
And Function

Abstract The aim of this study was to correlate dopamine receptors and D2 isoform expression with the cabergoline effect on α-subunit secretion in vitro and tumor mass in vivo in clinically nonfunctioning pituitary tumors. Eighteen patients were subjected to neurosurgery, and a tumor sample was used for dopamine receptor and D2 isoform expression evaluation by RT-PCR and the in vitro functional studies. After neurosurgery, nine of 18 patients with persistent tumor were treated with cabergoline and tumor mass was evaluated before and after 1 yr treatment. D2 receptor was expressed in 67% of cases. D2long was found in 50%, D2short in 17%, and both D2 isoforms in 33% of cases. D4 receptor was also expressed in 17% of cases. The in vitro inhibition of α-subunit concentration was found in 56% of cases and was associated with D2 expression (χ2 = 5.6; P < 0.05). After 1 yr of cabergoline treatment, tumor shrinkage was evident in 56% of patients and was associated with D2 expression (χ2 = 5.6; P < 0.05). The expression of D2short rather than D2long isoform is associated with the most favorable response of the tumor to cabergoline treatment. In conclusion, this study demonstrates D2 receptor expression and function in nearly 70% of cases, suggesting a role of this drug in the treatment schedule of clinically nonfunctioning pituitary tumors.

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