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Many Cellular Functions (many + cellular_function)
Selected AbstractsRapid separation of protein isoforms by capillary zone electrophoresis with new dynamic coatingsELECTROPHORESIS, Issue 11 2005William W. P. Chang Abstract Many cellular functions are regulated through protein isoforms. Changes in the expression level or regulatory dysfunctions of isoforms often lead to developmental or pathological disorders. Isoforms are traditionally analyzed using techniques such as gel- or capillary-based isoelectric focusing. However, with proper electroosmotic flow (EOF) control, isoforms with small pI differences can also be analyzed using capillary zone electrophoresis (CZE). Here we demonstrate the ability to quickly resolve isoforms of three model proteins (bovine serum albumin, transferrin, ,1 -antitrypsin) in capillaries coated with novel dynamic coatings. The coatings allow reproducible EOF modulation in the cathodal direction to a level of 10 -9 m2V -1s -1. They also appear to inhibit protein adsorption to the capillary wall, making the isoform separations highly reproducible both in peak areas and apparent mobility. Isoforms of transferrin and ,1 -antitrypsin have been implicated in several human diseases. By coupling the CZE isoform separation with standard affinity capture assays, it may be possible to develop a cost-effective analytical platform for clinical diagnostics. [source] Downregulation of protease-activated receptor-1 in human lung fibroblasts is specifically mediated by the prostaglandin E2 receptor EP2 through cAMP elevation and protein kinase AFEBS JOURNAL, Issue 14 2008Elena Sokolova Many cellular functions of lung fibroblasts are controlled by protease-activated receptors (PARs). In fibrotic diseases, PAR-1 plays a major role in controlling fibroproliferative and inflammatory responses. Therefore, in these diseases, regulation of PAR-1 expression plays an important role. Using the selective prostaglandin EP2 receptor agonist butaprost and cAMP-elevating agents, we show here that prostaglandin (PG)E2, via the prostanoid receptor EP2 and subsequent cAMP elevation, downregulates mRNA and protein levels of PAR-1 in human lung fibroblasts. Under these conditions, the functional response of PAR-1 in fibroblasts is reduced. These effects are specific for PGE2. Activation of other receptors coupled to cAMP elevation, such as ,-adrenergic and adenosine receptors, does not reproduce the effects of PGE2. PGE2 -mediated downregulation of PAR-1 depends mainly on protein kinase A activity, but does not depend on another cAMP effector, the exchange protein activated by cAMP. PGE2 -induced reduction of PAR-1 level is not due to a decrease of PAR-1 mRNA stability, but rather to transcriptional regulation. The present results provide further insights into the therapeutic potential of PGE2 to specifically control fibroblast function in fibrotic diseases. [source] Dynamical analysis of the calcium signaling pathway in cardiac myocytes based on logarithmic sensitivity analysisBIOTECHNOLOGY JOURNAL, Issue 5 2008Tae-Hwan Kim Abstract Many cellular functions are regulated by the Ca2+ signal which contains specific information in the form of frequency, amplitude, and duration of the oscillatory dynamics. Any alterations or dysfunctions of components in the calcium signaling pathway of cardiac myocytes may lead to a diverse range of cardiac diseases including hypertrophy and heart failure. In this study, we have investigated the hidden dynamics of the intracellular Ca2+ signaling and the functional roles of its regulatory mechanism through in silico simulations and parameter sensitivity analysis based on an experimentally verified mathematical model. It was revealed that the Ca2+ dynamics of cardiac myocytes are determined by the balance among various system parameters. Moreover, it was found through the parameter sensitivity analysis that the self-oscillatory Ca2+ dynamics are most sensitive to the Ca2+ leakage rate of the sarcolemmal membrane and the maximum rate of NCX, suggesting that these two components have dominant effects on circulating the cytosolic Ca2+. [source] Effect of selenium-supplement on the calcium signaling in human endothelial cells,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2005Yi Zheng Intracellular Ca2+ signaling controls many cellular functions. Understanding its regulation by selenoproteins is essential for understanding the role of selenoproteins in regulating cell functions. The activity of thioredoxin reductase (TrxR), thioredoxin (Trx) content, and the activity of glutathione peroxidase (GPx) in the human endothelial cells cultured in selenium-supplemented medium (refer as Se+ cells) was found 70%, 40%, and 20% higher, respectively than those in the cells cultured in normal medium (refer as Se0 cells). The intracellular Ca2+ signaling initiated by inositol 1,4,5-trisphosphate (IP3), histamine, thapsigargin (TG), carbonyl cyanide p -(tri-fluoromethoxy) phenyl-hydrazone (FCCP), and cyclosporin A (CsA) was investigated in both Se+ and Se0 cells. It was interestingly found that the higher activity of selenoproteins reduced the sensitivity of IP3 receptor to the IP3 -triggered Ca2+ release from intracellular stores, but enhanced activation of the receptor-coupled phospholipase C in histamine-stimulated Se+ cells by showing much more generation of IP3 and higher elevation of cytosolic Ca2+. The higher selenoprotein activity also reduced susceptibility of the uniporter to the mitochondrial uncoupler, susceptibility of the permeability transition pore (PTP) to its inhibitor, and the vulnerability of endoplasmic reticulum (ER) Ca2+ -ATPase to its inhibitor in selenium-supplementing cells. The results suggest that cell calcium signaling is subjected to thiol-redox regulation by selenoproteins. © 2005 Wiley-Liss, Inc. [source] Ethanol Blocks Adenosine Uptake via Inhibiting the Nucleoside Transport System in Bronchial Epithelial CellsALCOHOLISM, Issue 5 2009Diane S. Allen-Gipson Background:, Adenosine uptake into cells by nucleoside transporters plays a significant role in governing extracellular adenosine concentration. Extracellular adenosine is an important signaling molecule that modulates many cellular functions via 4 G-protein-coupled receptor subtypes (A1, A2A, A2B, and A3). Previously, we demonstrated that adenosine is critical in maintaining airway homeostasis and airway repair and that airway host defenses are impaired by alcohol. Taken together, we hypothesized that ethanol impairs adenosine uptake via the nucleoside transport system. Methods:, To examine ethanol-induced alteration on adenosine transport, we used a human bronchial epithelial cell line (BEAS-2B). Cells were preincubated for 10 minutes in the presence and absence of varying concentrations of ethanol (EtOH). In addition, some cells were pretreated with S-(4-Nitrobenzyl)-6-thioinosine (100 ,M: NBT), a potent adenosine uptake inhibitor. Uptake was then determined by addition of [3H]-adenosine at various time intervals. Results:, Increasing EtOH concentrations resulted in increasing inhibition of adenosine uptake when measured at 1 minute. Cells pretreated with NBT effectively blocked adenosine uptake. In addition, short-term EtOH revealed increased extracellular adenosine concentration. Conversely, adenosine transport became desensitized in cells exposed to EtOH (100 mM) for 24 hours. To determine the mechanism of EtOH-induced desensitization of adenosine transport, cAMP activity was assessed in response to EtOH. Short-term EtOH exposure (10 minutes) had little or no effect on adenosine-mediated cAMP activation, whereas long-term EtOH exposure (24 hours) blocked adenosine-mediated cAMP activation. Western blot analysis of lysates from unstimulated BEAS-2B cells detected a single 55 kDa band indicating the presence of hENT1 and hENT2, respectively. Real-time RT-PCR of RNA from BEAS-2B revealed transcriptional expression of ENT1 and ENT2. Conclusions:, Collectively, these data reveal that acute exposure of cells to EtOH inhibits adenosine uptake via a nucleoside transporter, and chronic exposure of cells to EtOH desensitizes the adenosine transporter to these inhibitory effects of ethanol. Furthermore, our data suggest that inhibition of adenosine uptake by EtOH leads to an increased extracellular adenosine accumulation, influencing the effect of adenosine at the epithelial cell surface, which may alter airway homeostasis. [source] Peroxisome proliferator-activated receptors in cutaneous biologyBRITISH JOURNAL OF DERMATOLOGY, Issue 2 2003S. Kuenzli Summary Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that regulate the expression of target genes involved in many cellular functions including cell proliferation, differentiation and immune/inflammation response. The PPAR subfamily consists of three isotypes: PPAR,, PPAR,/, and PPAR,, which have all been identified in keratinocytes. PPAR,/, is the predominant subtype in human keratinocytes, whereas PPAR, and PPAR, are expressed at much lower levels and increase significantly upon keratinocyte differentiation. PPAR,/, is not linked to differentiation, but is significantly upregulated upon various conditions that result in keratinocyte proliferation, and during skin wound healing. In vitro and in vivo evidence suggests that PPARs appear to play an important role in skin barrier permeability, inhibiting epidermal cell growth, promoting epidermal terminal differentiation and regulating skin inflammatory response by diverse mechanisms. These proprieties are pointing in the direction of PPARs being key regulators of skin conditions characterized by hyperproliferation, inflammatory infiltrates and aberrant differentiation such as psoriasis, but may also have clinical implications in inflammatory skin disease (e.g. atopic dermatitis), proliferative skin disease, wound healing, acne and protease inhibitor associated lipodystrophia. [source] Interaction of hydrogen sulfide with ion channelsCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 7 2010Guanghua Tang Summary 1. Hydrogen sulfide (H2S) is a signalling gasotransmitter. It targets different ion channels and receptors, and fulfils its various roles in modulating the functions of different systems. However, the interaction of H2S with different types of ion channels and underlying molecular mechanisms has not been reviewed systematically. 2. H2S is the first identified endogenous gaseous opener of ATP-sensitive K+ channels in vascular smooth muscle cells. Through the activation of ATP-sensitive K+ channels, H2S lowers blood pressure, protects the heart from ischemia and reperfusion injury, inhibits insulin secretion in pancreatic , cells, and exerts anti-inflammatory, anti-nociceptive and anti-apoptotic effects. 3. H2S inhibited L-type Ca2+ channels in cardiomyocytes but stimulated the same channels in neurons, thus regulating intracellular Ca2+ levels. H2S activated small and medium conductance KCa channels but its effect on BKCa channels has not been consistent. 4. H2S-induced hyperalgesia and pro-nociception seems to be related to the sensitization of both T-type Ca2+ channels and TRPV1 channels. The activation of TRPV1 and TRPA1 by H2S is believed to result in contraction of nonvascular smooth muscles and increased colonic mucosal Cl, secretion. 5. The activation of Cl, channel by H2S has been shown as a protective mechanism for neurons from oxytosis. H2S also potentiates N -methyl- d -aspartic acid receptor-mediated currents that are involved in regulating synaptic plasticity for learning and memory. 6. Given the important modulatory effects of H2S on different ion channels, many cellular functions and disease conditions related to homeostatic control of ion fluxes across cell membrane should be re-evaluated. [source] | |||||||||||||