Extracellular nucleotides elevate [Ca2+]i in rat osteoblastic cells by interaction with two receptor subtypes

1992 ◽  
Vol 263 (5) ◽  
pp. C1040-C1048 ◽  
Author(s):  
W. J. Reimer ◽  
S. J. Dixon
Keyword(s):  
Cell Types ◽  
Extracellular Nucleotides ◽  
Osteoblastic Cells ◽  
Osteoblastic Cell ◽  
Receptor Subtypes ◽  
Specific Cell ◽  
Extracellular Medium ◽  
Osteoblastic Cell Line ◽  
Surface Receptors ◽  
Biological Responses

Extracellular nucleotides, through interaction with specific cell-surface receptors, mediate a variety of biological responses, including elevation of cytosolic free Ca2+ concentration ([Ca2+]i) in a number of cell types. The effects of nucleotides on [Ca2+]i in the rat osteoblastic cell line UMR-106 were studied by fluorescence spectrophotometry of indo-1-loaded cells. In response to ATP (100 microM), [Ca2+]i rose to peaks 228 +/- 16 nM (n = 59) above baseline (85 +/- 3 nM) before returning to near basal levels. Half-maximal elevation of [Ca2+]i was observed at an ATP concentration of 3 +/- 1 microM, consistent with a high-affinity interaction. The response arose primarily by release of Ca2+ from internal stores. UTP, ADP, and 2-methylthioadenosine 5'-triphosphate also induced Ca2+ transients, whereas adenosine, AMP, CTP, and TTP did not, demonstrating specificity. Responsiveness to adenosine 5'-O-(3-thiotriphosphate) and inhibition by Mg2+ of the response to ATP indicated that signaling was not dependent on nucleotide hydrolysis. Ca2+ responses to ADP, ATP, and UTP, added sequentially or simultaneously, were consistent with the presence of two distinct P2-purinoceptor subtypes, both linked to Ca2+ mobilization. ADP appeared to interact selectively with one receptor, whereas ATP and UTP interacted selectively with the other. After maximal stimulation with ATP, subsequent responses to ATP were abolished. However, removal of ATP from the extracellular medium rapidly restored responsiveness, suggesting that, with continued receptor occupation, there is time-dependent inactivation of the Ca2+ signaling pathway. Our findings indicate that extracellular nucleotides elevate [Ca2+]i in osteoblastic cells through interaction with two receptor subtypes.(ABSTRACT TRUNCATED AT 250 WORDS)

Nanotheranostic agents for neurodegenerative diseases

2020 ◽  
Vol 4 (6) ◽  
pp. 645-675
Author(s):  
Parasuraman Padmanabhan ◽  
Mathangi Palanivel ◽  
Ajay Kumar ◽  
Domokos Máthé ◽  
George K. Radda ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Neurodegenerative Diseases ◽  
Cell Types ◽  
Specific Cell ◽  
Ageing Population ◽  
Target Tissue ◽  
Therapeutic Approaches ◽  
Surface Receptors ◽  
Theranostic Agents ◽  
Preclinical Animal Models

Neurodegenerative diseases (NDDs), including Alzheimer's disease (AD) and Parkinson's disease (PD), affect the ageing population worldwide and while severely impairing the quality of life of millions, they also cause a massive economic burden to countries with progressively ageing populations. Parallel with the search for biomarkers for early detection and prediction, the pursuit for therapeutic approaches has become growingly intensive in recent years. Various prospective therapeutic approaches have been explored with an emphasis on early prevention and protection, including, but not limited to, gene therapy, stem cell therapy, immunotherapy and radiotherapy. Many pharmacological interventions have proved to be promising novel avenues, but successful applications are often hampered by the poor delivery of the therapeutics across the blood-brain-barrier (BBB). To overcome this challenge, nanoparticle (NP)-mediated drug delivery has been considered as a promising option, as NP-based drug delivery systems can be functionalized to target specific cell surface receptors and to achieve controlled and long-term release of therapeutics to the target tissue. The usefulness of NPs for loading and delivering of drugs has been extensively studied in the context of NDDs, and their biological efficacy has been demonstrated in numerous preclinical animal models. Efforts have also been made towards the development of NPs which can be used for targeting the BBB and various cell types in the brain. The main focus of this review is to briefly discuss the advantages of functionalized NPs as promising theranostic agents for the diagnosis and therapy of NDDs. We also summarize the results of diverse studies that specifically investigated the usage of different NPs for the treatment of NDDs, with a specific emphasis on AD and PD, and the associated pathophysiological changes. Finally, we offer perspectives on the existing challenges of using NPs as theranostic agents and possible futuristic approaches to improve them.

scholarly journals Prostaglandin E receptor subtypes in mouse osteoblastic cell line.

Endocrinology ◽  
1996 ◽  
Vol 137 (5) ◽  
pp. 1698-1705 ◽  
Author(s):  
M Suda ◽  
K Tanaka ◽  
K Natsui ◽  
T Usui ◽  
I Tanaka ◽  
...  
Keyword(s):  
Cell Line ◽  
Osteoblastic Cell ◽  
Prostaglandin E ◽  
Receptor Subtypes ◽  
Osteoblastic Cell Line

scholarly journals Cholinergic suppression of visual responses in primate V1 is mediated by GABAergic inhibition

2012 ◽  
Vol 108 (7) ◽  
pp. 1907-1923 ◽  
Author(s):  
Anita A. Disney ◽  
Chiye Aoki ◽  
Michael J. Hawken
Keyword(s):  
Glutamate Release ◽  
Cell Types ◽  
Cholinergic Receptor ◽  
Receptor Subtypes ◽  
Specific Cell ◽  
Visual Responses ◽  
Ach Release ◽  
Anatomical Studies ◽  
Gain Enhancement ◽  
Tuning Width

Acetylcholine (ACh) has been implicated in selective attention. To understand the local circuit action of ACh, we iontophoresed cholinergic agonists into the primate primary visual cortex (V1) while presenting optimal visual stimuli. Consistent with our previous anatomical studies showing that GABAergic neurons in V1 express ACh receptors to a greater extent than do excitatory neurons, we observed suppressed visual responses in 36% of recorded neurons outside V1's primary thalamorecipient layer (4c). This suppression is blocked by the GABAA receptor antagonist gabazine. Within layer 4c, ACh release produces a response gain enhancement (Disney AA, Aoki C, Hawken MJ. Neuron 56: 701–713, 2007); elsewhere, ACh suppresses response gain by strengthening inhibition. Our finding contrasts with the observation that the dominant mechanism of suppression in the neocortex of rats is reduced glutamate release. We propose that in primates, distinct cholinergic receptor subtypes are recruited on specific cell types and in specific lamina to yield opposing modulatory effects that together increase neurons' responsiveness to optimal stimuli without changing tuning width.

Novel insights into how purines regulate pituitary cell function

2003 ◽  
Vol 104 (5) ◽  
pp. 467-481 ◽  
Author(s):  
D. Aled REES ◽  
Maurice F. SCANLON ◽  
Jack HAM
Keyword(s):  
Pituitary Gland ◽  
Cell Function ◽  
Adenine Nucleotides ◽  
Growth Control ◽  
Cell Types ◽  
Pituitary Cell ◽  
Receptor Subtypes ◽  
Diverse Range ◽  
Surface Receptors ◽  
Signalling Molecules

Purine nucleosides and nucleotides are widely distributed substances that exhibit a diverse range of effects in a number of tissues, acting as important extracellular signalling molecules in addition to their more established roles in cellular metabolism. They mediate their effects via activation of distinct cell surface receptors, termed adenosine (or P1) and P2 purinergic receptors. Although roles for adenosine and adenine nucleotides have been described previously in the pituitary gland, the distribution of the receptor subtypes and the effects of their activation on pituitary function are not well defined. Recent evidence, however, has emerged to describe a complex signalling system for purines in the pituitary gland. Data from a variety of studies have shown that the expression pattern, number and affinity of adenosine and/or P2 receptors may be cell-type specific and that non-endocrine in addition to endocrine cells elaborate these receptors. These variations, along with the diverse range of signalling pathways activated, dictate the response of individual cell types to extracellular purines, with roles now emerging for these substances in the regulation of hormone release, pituitary cell proliferation and cytokine/growth factor expression. In this review, we discuss these advances and examine some implications for pituitary growth control and the response of the hypothalamic–pituitary–adrenal axis to stress and inflammation.

scholarly journals Type 2 Iodothyronine Selenodeiodinase Is Expressed throughout the Mouse Skeleton and in the MC3T3-E1 Mouse Osteoblastic Cell Line during Differentiation

Endocrinology ◽  
2005 ◽  
Vol 146 (1) ◽  
pp. 195-200 ◽  
Author(s):  
Cecilia H. A. Gouveia ◽  
Marcelo A. Christoffolete ◽  
Clarissa R. Zaitune ◽  
José Miguel Dora ◽  
John W. Harney ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Cell Line ◽  
Bone Cells ◽  
Bone Development ◽  
Cell Types ◽  
Osteoblastic Cell ◽  
Dependent Manner ◽  
Osteoblastic Cell Line ◽  
Serum T3

Thyroid hormone affects multiple aspects of bone metabolism, but little is known about thyroid hormone deiodination in bone cells except that cultures of skeletal cells and bone organ express types 1 and 2 iodothyronine deiodinases (D1 and D2) mRNAs. In the present study, outer ring deiodination (ORD) activity was detected in bone extracts of multiple sites of the mouse skeleton, bone marrow, and the MC3T3-E1 osteoblastic cell line. In all tissues, ORD was detected using 125I-rT3 or 125I-T4 as substrates and was found to be 6-n-propylthiouracil insensitive, display a Michaelis constant (T4) of approximately 1 nm, increase about 3-fold in hypo- and virtually disappear in thyrotoxicosis. Extracts of calvaria had the lowest ORD activity, whereas tibial and femoral extracts had roughly three times as much. The absence of ORD activity in bone extracts from mice with targeted disruption of the Dio2 gene confirms the principal role of D2 in this tissue. In the MC3T3-E1 osteoblasts, D2 activity increased in a time-dependent manner after plating, and with the content of selenium in the media, reaching a maximum 5–7 d later as cells attained more than 90% confluence. In these cells D2 half-life is about 30–40 min, which is further accelerated by exposure to substrate and stabilized by the proteasome inhibitor, MG132. Treatment with vitamin D [1,25(OH)2VD]-induced D2 activity by 2- to 3-fold as early as 24 h, regardless of the level of cell confluence, but estradiol, PTH, forskolin, leptin, TNFα, TGFβ, and dexamethasone did not affect D2. Given the role of D2 in other cell types and processes, it is likely that bone ORD not only plays a role in bone development and adult bone T3 homeostasis but also contributes to extrathyroidal T3 production and maintenance of serum T3.

Twisting integrin receptors increases endothelin-1 gene expression in endothelial cells

2001 ◽  
Vol 280 (6) ◽  
pp. C1475-C1484 ◽  
Author(s):  
Jianxin Chen ◽  
Ben Fabry ◽  
Ernesto L. Schiffrin ◽  
Ning Wang
Keyword(s):  
Gene Expression ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Specific Cell ◽  
Integrin Receptors ◽  
Hla Antigen ◽  
Surface Receptors ◽  
Endothelin 1 ◽  
Biological Responses ◽  
Cytoskeletal Tension

A magnetic twisting stimulator was developed based on the previously published technique of magnetic twisting cytometry. Using ligand-coated ferromagnetic microbeads, this device can apply mechanical stresses with varying amplitudes, duration, frequencies, and waveforms to specific cell surface receptors. Biochemical and biological responses of the cells to the mechanical stimulation can be assayed. Twisting integrin receptors with RGD (Arg-Gly-Asp)-containing peptide-coated beads increased endothelin-1 (ET-1) gene expression by >100%. In contrast, twisting scavenger receptors with acetylated low-density lipoprotein-coated beads or twisting HLA antigen with anti-HLA antibody-coated beads did not lead to alterations in ET-1 gene expression. In situ hybridization showed that the increase in ET-1 mRNA was localized in the cells that were stressed with the RGD-coated beads. Blocking stretch-activated ion channels with gadolinium, chelating Ca2+ with EGTA, or inhibiting tyrosine phosphorylation with genistein abolished twist-induced ET-1 mRNA elevation. Abolishing cytoskeletal tension with an inhibitor of the myosin ATPase, with an inhibitor of myosin light chain kinase, or with an actin microfilament disrupter blocked twisted-induced increases in ET-1 expression. Our results are consistent with the hypothesis that the molecular structural linkage of integrin-cytoskeleton is an important pathway for stress-induced ET-1 gene expression.

scholarly journals Fibroblast Growth Factor Receptor 2 Phosphorylation on Serine 779 Couples to 14-3-3 and Regulates Cell Survival and Proliferation

2008 ◽  
Vol 28 (10) ◽  
pp. 3372-3385 ◽  
Author(s):  
Ana Lonic ◽  
Emma F. Barry ◽  
Cindy Quach ◽  
Bostjan Kobe ◽  
Neil Saunders ◽  
...  
Keyword(s):  
Cell Surface ◽  
Cell Survival ◽  
Intracellular Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Cell Surface Receptors ◽  
Specific Cell ◽  
Fibroblast Growth ◽  
Surface Receptors ◽  
Biological Responses ◽  
Cell Survival And Proliferation

ABSTRACT The fibroblast growth factors (FGFs) exert their diverse (or pleiotropic) biological responses through the binding and activation of specific cell surface receptors (FGFRs). While FGFRs are known to initiate intracellular signaling through receptor tyrosine phosphorylation, the precise mechanisms by which the FGFRs regulate pleiotropic biological responses remain unclear. We now identify a new mechanism by which FGFR2 is able to regulate intracellular signaling and cellular responses. We show that FGFR2 is phosphorylated on serine 779 (S779) in response to FGF2. S779, which lies adjacent to the phospholipase Cγ binding site at Y766, provides a docking site for the 14-3-3 phosphoserine-binding proteins and is essential for the full activation of the phosphatidylinositol 3-kinase and Ras/mitogen-activated protein kinase pathways. Furthermore, S779 signaling is essential for promoting cell survival and proliferation in both Ba/F3 cells and BALB/c 3T3 fibroblasts. This new mode of FGFR2 phosphoserine signaling via the 14-3-3 proteins may provide an increased repertoire of signaling outputs to allow the regulation of pleiotropic biological responses. In this regard, we have identified conserved putative phosphotyrosine/phosphoserine motifs in the cytoplasmic domains of diverse cell surface receptors, suggesting that they may perform important functional roles beyond the FGFRs.

scholarly journals Characterization of the cytotoxic effect of extracellular ATP in J774 mouse macrophages

1992 ◽  
Vol 288 (3) ◽  
pp. 897-901 ◽  
Author(s):  
M Murgia ◽  
P Pizzo ◽  
T H Steinberg ◽  
F Di Virgilio
Keyword(s):  
Plasma Membrane ◽  
Membrane Permeability ◽  
Cell Types ◽  
Mouse Cell ◽  
Extracellular Atp ◽  
Cell Swelling ◽  
Specific Cell ◽  
Plasma Membrane Permeability ◽  
Experimental Conditions ◽  
Surface Receptors

Extracellular ATP (ATPo) is known to be cytotoxic to many cell types through a mechanism which is largely unknown. Very recently this nucleotide has been shown to cause cell death by apoptosis, probably by interacting with specific cell-surface receptors. In the present study we have investigated the mechanism of ATPo-dependent cytotoxicity in the macrophage-like mouse cell line J774. It has been previously reported that in this cell type ATPo activates trans-membrane Ca2+ and Na+ fluxes and a drastic increase in the plasma-membrane permeability to hydrophilic solutes smaller than 900 Da. These changes are followed by cell swelling and lysis. We show in the present study that, although this nucleotide triggers a rise in the cytoplasmic Ca2+ concentration, neither cell swelling nor lysis is Ca(2+)-dependent. Furthermore, cell lysis is not dependent on Na+ influx, as it is not prevented by iso-osmotic replacement of extracellular Na+ with choline or N-methylglucamine. On the contrary, ATPo-dependent cytotoxicity, but not the ATPo-dependent increase in plasma-membrane permeability, is completely abrogated in sucrose medium. Under our experimental conditions ATPo does not cause DNA fragmentation in J774 cells. We conclude from these findings that ATPo does not cause apoptosis of J774 macrophages and promotes a Ca(2+)- and Na(+)-independent colloido-osmotic lysis.

Role of microtubule-associated proteins in the control of microtubule assembly

1995 ◽  
Vol 75 (4) ◽  
pp. 835-864 ◽  
Author(s):  
R. B. Maccioni ◽  
V. Cambiazo
Keyword(s):  
Posttranslational Modifications ◽  
Mammalian Cells ◽  
Intracellular Transport ◽  
Cell Types ◽  
Regulatory Elements ◽  
Microtubule Assembly ◽  
Specific Cell ◽  
Surface Receptors ◽  
Microtubule Associated Proteins ◽  
Associated Proteins

In eukaryotic cells, microtubules, actin, and intermediate filaments interact to form the cytoskeletal network involved in determination of cell architecture, intracellular transport, modulation of surface receptors, mitosis, cell motility, and differentiation. Cytoskeletal organization and dynamics depend on protein self-associations and interactions with regulatory elements such as microtubule-associated proteins (MAPs). The MAP family includes large proteins like MAP-1A, MAP-1B, MAP-1C, MAP-2, and MAP-4 and smaller components like tau and MAP-2C. This review focuses on relevant aspects of MAP function, with emphasis on their roles in modulating cytoskeletal interactions. In this context, MAP expression mechanisms and posttranslational modifications are also discussed. Microtubule-associated proteins have a rather widespread distribution among cells, but certain MAPs have been identified in specific cell types. Within single neurons, MAP-2 is dendritic while tau is preferentially an axonal protein. Their expression is developmentally regulated. Even though MAPs share a capacity to interact with the COOH-terminal tubulin domain, stabilize microtubules, and link them with other cytoskeletal polymers, they exhibit structural differences. However, MAP-2, MAP-4, and tau have common repetitive microtubule-binding motifs. Microtubule-associated proteins not only control cytoskeletal integrity, but they also appear to interact with highly structural elements of cells. Molecular biological approaches permitted localization of new MAPs in cultured mammalian cells and invertebrate organisms and other microtubule-interacting proteins that exhibit transient interactions with microtubules. The structural/functional aspects of several new MAP-like proteins in centrosomes and the mitotic spindle, functionally implicated in cell cycle events, are also analyzed.

Effects of Transforming Growth Factor-β1 on Decorin Expression by Undifferentiated Osteoblastic Cells

1997 ◽  
Vol 3 (S2) ◽  
pp. 187-188
Author(s):  
T. Yamada ◽  
N. Kubushiro ◽  
K. Shigemasa ◽  
T. Ikeda ◽  
M. Takagi
Keyword(s):  
Growth Factor ◽  
Cell Line ◽  
Transforming Growth Factor ◽  
Bone Cells ◽  
Bone Matrix ◽  
Transforming Growth Factor Β ◽  
Osteoblastic Cells ◽  
Osteoblastic Cell ◽  
Experimental Conditions ◽  
Osteoblastic Cell Line

Decorin is the predominant proteoglycan isolated from bone of several animal species. Bone matrix decorin appears to bind transforming growth factor β (TGF-β) and enhances its bioactivity. TGF-β is stored in bone matrix in abundant amounts and modulates the synthesis of bone matrix proteins by osteoblasts. Thus it appears to play a role in regulation of bone formation during the bone remodeling process. The effect of TGF-β on decorin expression in bone cells has been evaluated in murine osteoblastic cells, but the results are divergent depending on the experimental conditions and cell types used. The present study investigated the effect of TGF-βl on the expression of decorin mRNA in two clonal rat osteoblastic cell lines with different stages of differentiation, ROS-C26 (C26) and ROS-C20 (C20); C26 is a potential osteoblast precursor cell line that is also capable of differentiating into muscle cells and adipocytes; C20 is a more differentiated osteoblastic cell line.

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