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Buzard D, Han S, Thoresen L, Moody J, Lopez L, Kawasaki A, Schrader T, Sage C, Gao Y, Edwards J, Barden J, Thatte J, Fu L, Solomon M, Liu L, Al-Shamma H, Gatlin J, Le M, Xing C, Espinola S, Jones RM. Discovery and characterization of potent and selective 4-oxo-4-(5-(5-phenyl-1,2,4-oxadiazol-3-yl)indolin-1-yl)butanoic acids as S1P₁ agonists. Bioorg Med Chem Lett 2011; 21:6013-8. [PMID: 21852130 DOI: 10.1016/j.bmcl.2011.05.110] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 05/25/2011] [Accepted: 05/26/2011] [Indexed: 11/27/2022]
Abstract
S1P(1) receptor driven lymphopenia has proven utility in the treatment of an array of autoimmune disease states. As a part of our efforts to develop potent and selective S1P(1) receptor agonists, we have identified a novel chemical series of 4-oxo-4-(5-(5-phenyl-1,2,4-oxadiazol-3-yl)indolin-1-yl)butanoic acid S1P(1) receptor agonists.
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Affiliation(s)
- Daniel Buzard
- Arena Pharmaceuticals, 6166 Nancy Ridge Drive, San Diego, CA 92121, USA
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2
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3
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G protein-coupled receptor mediated trimethylamine sensing. Biosens Bioelectron 2009; 25:715-20. [PMID: 19734032 DOI: 10.1016/j.bios.2009.08.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2009] [Revised: 08/04/2009] [Accepted: 08/07/2009] [Indexed: 11/20/2022]
Abstract
A new approach for the detection of trimethylamine (TMA) using a recombinant cell line of Xenopus laevis melanophores was developed. The cells were genetically modified to express the mouse trace amine-associated receptor 5 (mTAAR5), a G protein-coupled receptor from the mouse olfactory epithelium, which conferred high sensitivity to TMA. Cellular responses to TMA were analyzed by two different techniques, either by absorbance measurements using a microplate reader or by cellular imaging via an inverted microscope. A focused chemical screen allowed the discovery of additional, previously unknown stimuli of mTAAR5. The developed cell-based sensor demonstrated no sensitivity to trimethylamine N-oxide (TMAO), making it suitable for a straightforward evaluation of TMA levels in fish tissue extracts. For the detection of TMA vapor, the cells were covered with agarose, which allowed for intact cell viability for at least 6h in air. The developed gas measurement platform was able to detect TMA from 1 to 100 ppm within 35 min.
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4
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Eriksson TL, Svensson SPS, Lundström I, Persson K, Andersson TPM, Andersson RGG. Panax ginseng induces anterograde transport of pigment organelles in Xenopus melanophores. JOURNAL OF ETHNOPHARMACOLOGY 2008; 119:17-23. [PMID: 18639398 DOI: 10.1016/j.jep.2008.05.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Revised: 05/19/2008] [Accepted: 05/22/2008] [Indexed: 05/26/2023]
Abstract
Melanophores from Xenopus laevis are pigmented cells, capable of quick colour changes through cyclic adenosine 3':5'-monophosphate (cAMP) coordinated transport of their intracellular pigment granules, melanosomes. In this study we use the melanophore cell line to evaluate the effects of Panax ginseng extract G115 on organelle transport. Absorbance readings of melanophore-coated microplates, Correlate-EIA direct cAMP enzyme immunoassay kit, and western blot were used to measure the melanosome movement and changes in intracellular signalling. We show that Panax ginseng induces a fast concentration-dependent anterograde transport of the melanosomes. No significant increase in the cAMP level was seen and pre-incubation of melanophores with the protein kinase C (PKC) inhibitor EGF-R Fragment 651-658 (M-EGF) only partly decreased the ginseng-induced dispersion. We also demonstrate that Panax ginseng, endothelin-3 (ET-3) and alpha-melanocyte stimulating hormone (MSH) stimulate an activation of mitogen activated protein kinase (MAPK). Pre-incubation with M-EGF decreased the MAPK activity induced by ET-3 and MSH, but again only marginally affected the response of Panax ginseng. Thus, in melanophores we suggest that Panax ginseng stimulates an anterograde transport of pigment organelles via a non-cAMP and mainly PKC-independent pathway.
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Affiliation(s)
- Therese L Eriksson
- Division of Drug Research/Pharmacology, Department of Medical and Health Sciences, Linköping University, SE-581 85 Linköping, Sweden.
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5
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Suska A, Ibáñez AB, Filippini D, Lundström I. Addressing Variability in aXenopus laevisMelanophore Cell Line. Assay Drug Dev Technol 2008; 6:569-76. [DOI: 10.1089/adt.2008.140] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Anke Suska
- Division of Applied Physics, Department of Physics, Chemistry, and Biology, Linköping University, Linköping, Sweden
| | - Ana B. Ibáñez
- Division of Applied Physics, Department of Physics, Chemistry, and Biology, Linköping University, Linköping, Sweden
| | - Daniel Filippini
- Division of Applied Physics, Department of Physics, Chemistry, and Biology, Linköping University, Linköping, Sweden
| | - Ingemar Lundström
- Division of Applied Physics, Department of Physics, Chemistry, and Biology, Linköping University, Linköping, Sweden
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6
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Andersson TPM, Filippini D, Suska A, Johansson TL, Svensson SPS, Lundström I. Frog melanophores cultured on fluorescent microbeads: biomimic-based biosensing. Biosens Bioelectron 2008; 21:111-20. [PMID: 15967358 DOI: 10.1016/j.bios.2004.08.043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Revised: 08/23/2004] [Accepted: 08/24/2004] [Indexed: 11/20/2022]
Abstract
Melanophores are pigmented cells in lower vertebrates capable of quick color changes and thereby suitable as whole cell biosensors. In the frog dermis skin layer, the large and dark pigmented melanophore surrounds a core of other pigmented cells. Upon hormonal stimulation the black-brown pigment organelles will redistribute within the melanophore, and thereby cover or uncover the core, making complex color changes possible in the dermis. Previously, melanophores have only been cultured on flat surfaces. Here we mimic the three dimensional biological geometry in the frog dermis by culturing melanophores on fluorescent plastic microbeads. To demonstrate biosensing we use the hormones melatonin and alpha-melanocyte stimulating hormone (alpha-MSH) as lightening or darkening stimuli, respectively. Cellular responses were successfully demonstrated on single cell level by fluorescence microscopy, and in cell suspension by a fluorescence microplate reader and a previously demonstrated computer screen photo-assisted technique. The demonstrated principle is the first step towards "single well/multiple read-out" biosensor arrays based on suspensions of different selective-responding melanophores, each cultured on microbeads with distinctive spectral characteristics. By applying small amount of a clinical sample, or a candidate substance in early drug screening, to a single well containing combinations of melanophores on beads, multiple parameter read-outs will be possible.
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Affiliation(s)
- Tony P M Andersson
- Division of Applied Physics, Department of Physics and Measurement Technology, Linköping University, SE-581 83 Linköping, Sweden.
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7
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Suska A, Filippini D, Andersson TPM, Lundström I. Generation of biochemical response patterns of different substances using a whole cell assay with multiple signaling pathways. Biosens Bioelectron 2005; 21:727-34. [PMID: 16242611 DOI: 10.1016/j.bios.2005.01.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2004] [Revised: 01/10/2005] [Accepted: 01/10/2005] [Indexed: 11/21/2022]
Abstract
Distinctive generation of biochemical response patterns of eight different substances, using an assay based on pigment containing cells, was demonstrated. Xenopus laevis melanophores, transfected with human beta(2)-adrenergic receptor, were seeded in a 96 well microplate and used to generate individual biochemical images through a two transient measuring protocol that contributes to highlight the response signatures of the agents. Adequate signal processing creates distinctive patterns in a time-concentration response space suitable for substance classification. The concept of biochemical images is introduced here. The assays were evaluated both with a standard microplate reader and with a computer screen photo-assisted technique (CSPT) yielding similar results. Since CSPT platforms only demand standard computer sets and web cameras as measuring setup, applications for these kind of assays outside main-laboratories were discussed.
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Affiliation(s)
- Anke Suska
- Division of Applied Physics, Department of Physics and Measurement Technology, Linköping University, SE-581 83, Sweden.
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8
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Isoldi MC, Rollag MD, Castrucci AMDL, Provencio I. Rhabdomeric phototransduction initiated by the vertebrate photopigment melanopsin. Proc Natl Acad Sci U S A 2005; 102:1217-21. [PMID: 15653769 PMCID: PMC545850 DOI: 10.1073/pnas.0409252102] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Melanopsin is the photopigment that confers light sensitivity on intrinsically photosensitive retinal ganglion cells. Mammalian intrinsically photosensitive retinal ganglion cells are involved in the photic synchronization of circadian rhythms to the day-night cycle. Here, we report molecular components of melanopsin signaling using the cultured Xenopus dermal melanophore system. Photo-activated melanopsin is shown to initiate a phosphoinositide signaling pathway similar to that found in invertebrate photo-transduction. In melanophores, light increases the intracellular level of inositol trisphosphate and causes the dispersion of melanosomes. Inhibition of phospholipase C and protein kinase C and chelation of intracellular calcium block the effect of light on melanophores. At least four proteins, 43, 74, 90, and 134 kDa, are phosphorylated by protein kinase C upon light stimulation. This provides evidence of an invertebrate-like light-activated signaling cascade within vertebrate cells.
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Affiliation(s)
- Mauro Cesar Isoldi
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
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9
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Andersson TPM, Sköld HN, Svensson SPS. Phosphoinositide 3-kinase is involved in Xenopus and Labrus melanophore aggregation. Cell Signal 2004; 15:1119-27. [PMID: 14575867 DOI: 10.1016/s0898-6568(03)00111-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Melanophores are pigmented cells capable of quick colour changes through coordinated transport of their intracellular pigment granules. We demonstrate the involvement of phosphoinositide 3-kinase (PI3-K) in Xenopus and Labrus aggregation by the use of the PI3-K inhibitor, LY-294002. In Xenopus, wortmannin-insensitive PI3-K was found to be essential for the aggregation, mitogen-activated protein kinase (MAPK) activation and tyrosine phosphorylation of a 280-kDa protein, and for the maintenance of low cyclic adenosine 3':5'-monophosphate (cAMP) during the aggregated state. Pre-aggregated cells disperse completely to LY-294002 at 50-100 muM, involving a transient elevation in cAMP due to adenylate cyclase (AC) stimulation or to inhibition of cyclic nucleotide phosphodiesterase (PDE). The inactive analogue LY-303511 did not induce dispersion at the same concentrations. PDE4 and/or PDE2 was found to be involved in melanosome aggregation. The similar kinetics of LY-294002 and various PDE inhibitors indicates that the elevation of cAMP might be due to inhibition of PDE. In Labrus melanophores, LY-294002 had a less dramatic effect, probably due to less dependence on PDE in regulation of cAMP levels. In Xenopus aggregation, we suggest that melatonin stimulation of the Mel1c receptor via G(beta gamma) activates PI3-K that, directly or indirectly via MAPK, activates PDE.
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Affiliation(s)
- Tony P M Andersson
- Division of Pharmacology, Department of Medicine and Care, Faculty of Health Sciences, Linköping University, SE-581 85 Linköping, Sweden.
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10
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Filippini D, Andersson TPM, Svensson SPS, Lundström I. Microplate based biosensing with a computer screen aided technique. Biosens Bioelectron 2004; 19:35-41. [PMID: 14558996 DOI: 10.1016/s0956-5663(03)00132-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Melanophores, dark pigment cells from the frog Xenopus laevis, have the ability to change light absorbance upon stimulation by different biological agents. Hormone exposure (e.g. melatonin or alpha-melanocyte stimulating hormone) has been used here as a reversible stimulus to test a new compact microplate reading platform. As an application, the detection of the asthma drug formoterol in blood plasma samples is demonstrated. The present system utilizes a computer screen as a (programmable) large area light source, and a standard web camera as recording media enabling even kinetic microplate reading with a versatile and broadly available platform, which suffices to evaluate numerous bioassays. Especially in the context of point of care testing or self testing applications these possibilities become advantageous compared with highly dedicated comparatively expensive commercial systems.
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Affiliation(s)
- Daniel Filippini
- Division of Applied Physics, Institute of Physics and Measurement Technology, Linköping University, SE-581 83 Linköping, Sweden.
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11
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Knight PJK, Pfeifer TA, Grigliatti TA. A functional assay for G-protein-coupled receptors using stably transformed insect tissue culture cell lines. Anal Biochem 2003; 320:88-103. [PMID: 12895473 DOI: 10.1016/s0003-2697(03)00354-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insect cells are an underexplored resource for functional G-protein-coupled receptor (GPCR) assays, despite a strong record in biochemical (binding) assays. Here we describe the use of vectors capable of creating stably transformed insect cell lines to generate a cell-based functional GPCR assay. This assay employs the luminescent photoprotein aequorin and the promiscuous G-protein subunit Galpha16 and is broadly applicable to human GPCRs. We demonstrate that the assay can quantitate ligand concentration-activity relationships for seven different human GPCRs, can differentiate between partial and full agonists, and can determine rank order potencies for both agonists and antagonists that match those seen with other assay systems. Human Galpha16 improves signal strength but is not required for activity with some receptors. The coexpression of human and bovine betagamma subunits and/or phospholipase Cbeta makes no difference to agonist efficacy or potency. Two different receptors expressed in the same cell line respond to their specific agonists, and two different cell lines (Sf9 and High 5) are able to functionally detect the same expressed GPCR. Sf9 cells have the capability to produce fully functional human receptors, allied to a low background of endogenous receptors, and so are a valuable system for investigating orphan GPCRs and receptor dimerization.
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Affiliation(s)
- Peter J K Knight
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Rm 3444, Vancouver, British Columbia, Canada, V6T 1Z4
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12
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Andersson TPM, Svensson SPS, Karlsson AM. Regulation of melanosome movement by MAP kinase. PIGMENT CELL RESEARCH 2003; 16:215-21. [PMID: 12753388 DOI: 10.1034/j.1600-0749.2003.00048.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Our objectives were to further characterize the signaling pathways in melatonin-induced aggregation in Xenopus melanophores, specifically to investigate a possible role of mitogen-activated protein kinase (MAPK). By Western blotting we found that melatonin activates MAPK, which precedes melanosome aggregation measured in a microplate reader. Activation of MAPK, tyrosine phosphorylation of a previously described 280-kDa protein, and melanosome aggregation are sensitive to PD98059, a selective inhibitor of MAPK kinase. The MAPK activation is also decreased by the adenylate cyclase stimulant forskolin. In summary, we found that MAPK is activated during melatonin-induced melanosome aggregation. Activation was decreased by an inhibitor of MAPK kinase, and by forskolin. In addition to inhibition of cyclic adenosine 3',5'-monophosphate (cAMP), reduction in protein kinase A activity (PKA), and activation of protein phosphatase 2A, we suggest that melatonin receptors activate the MAPK cascade and tyrosine phosphorylation of the 280-kDa protein. Although the cAMP/PKA signaling pathway is the most prominent, our data suggest that simultaneous activation of the MAPK cascade is of importance to obtain a completely aggregated state. This new regulatory mechanism of organelle transport by the MAPK cascade might be important in other eukaryotic cells.
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Affiliation(s)
- Tony P M Andersson
- Department of Medicine and Care, Division of Pharmacology, Faculty of Health Sciences, Linköping University, Linköping, Sweden
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13
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Ahn SG, Liu PC, Klyachko K, Morimoto RI, Thiele DJ. The loop domain of heat shock transcription factor 1 dictates DNA-binding specificity and responses to heat stress. Genes Dev 2001; 15:2134-45. [PMID: 11511544 PMCID: PMC312766 DOI: 10.1101/gad.894801] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Eukaryotic heat shock transcription factors (HSF) regulate an evolutionarily conserved stress-response pathway essential for survival against a variety of environmental and developmental stresses. Although the highly similar HSF family members have distinct roles in responding to stress and activating target gene expression, the mechanisms that govern these roles are unknown. Here we identify a loop within the HSF1 DNA-binding domain that dictates HSF isoform specific DNA binding in vitro and preferential target gene activation by HSF family members in both a yeast transcription assay and in mammalian cells. These characteristics of the HSF1 loop region are transposable to HSF2 and sufficient to confer DNA-binding specificity, heat shock inducible HSP gene expression and protection from heat-induced apoptosis in vivo. In addition, the loop suppresses formation of the HSF1 trimer under basal conditions and is required for heat-inducible trimerization in a purified system in vitro, suggesting that this domain is a critical part of the HSF1 heat-stress-sensing mechanism. We propose that this domain defines a signature for HSF1 that constitutes an important determinant for how cells utilize a family of transcription factors to respond to distinct stresses.
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Affiliation(s)
- S G Ahn
- Department of Biological Chemistry, The University of Michigan Medical School, Ann Arbor, Michigan 48109-0606, USA
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14
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Abstract
Black pigment cells called melanophores change colour in response to environmental changes and have lately been studied as promising biosensors. To further elucidate the intracellular processes involved in the colour changes of these cells, and to find optimal biosensing principles, the electric charge of intracellular pigment granules, melanosomes, has been determined in vitro by electrophoresis. Melanosomes from the two extreme states in the cell colour change (aggregated and dispersed melanosomes) were measured. The charge was found to be -1.5 x 10(-16) and -1.7 x 10(-16) C, aggregated and dispersed melanosomes, respectively, without significant difference between the two conditions. This charge is of the same order of magnitude as the one of 1000 electrons. The origin of the melanosome charge, and the use of these findings in new biosensor principles, is discussed.
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Affiliation(s)
- M F Testorf
- Department of Biomedical Engineering, University Hospital, Linköping University, Sweden.
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15
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Rollag MD, Provencio I, Sugden D, Green CB. Cultured amphibian melanophores: a model system to study melanopsin photobiology. Methods Enzymol 2000; 316:291-309. [PMID: 10800682 DOI: 10.1016/s0076-6879(00)16730-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- M D Rollag
- Department of Anatomy and Cell Biology, Uniformed Services University, Bethesda, Maryland 20815, USA
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16
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Karlsson AM, Lerner MR, Unett D, Lundström I, Svensson SP. Melatonin-induced organelle movement in melanophores is coupled to tyrosine phosphorylation of a high molecular weight protein. Cell Signal 2000; 12:469-74. [PMID: 10989282 DOI: 10.1016/s0898-6568(00)00089-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Melanophores, brown to black pigment cells from, for example, Xenopus laevis, contain mobile melanin filled organelles, and are well suited for studies on organelle movement. The intracellular regulation of the movement seems to be controlled by serine and threonine phosphorylations and dephosphorylations. Melatonin induces aggregation of the melanosomes to the cell centre through a G(i/o)-protein-coupled receptor, Mel1c, which leads to an inhibition of PKA and a stimulation of PP2A. However, this study shows that the melatonin-induced aggregation of melanosomes is also accompanied by tyrosine phosphorylation of a protein with a molecular weight of approximately 280 kDa. Cells pre-incubated with genistein, an inhibitor of tyrosine phosphorylations, showed inhibited melanosome movement after melatonin stimulation, and a lower degree of tyrosine phosphorylation of the approximately 280 kDa protein. The adenylyl cyclase activator forskolin, and the G(i/o) protein inhibitor pertussis toxin, also inhibited tyrosine phosphorylation of the approximately 280 kDa protein. The results indicate that melatonin stimulation generates tyrosine phosphorylation of a high molecular weight protein, an event that seems to be essential for melanosome aggregation.
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Affiliation(s)
- A M Karlsson
- Department of Medicine and Care, Pharmacology, Faculty of Health Sciences, Linköpings universitet, SE-581 85, Linköping, Sweden.
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17
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Xu F, Bose SC, McClintock TS. Lobster G-protein coupled receptor kinase that associates with membranes and G(beta) in response to odorants and neurotransmitters. J Comp Neurol 1999; 415:449-59. [PMID: 10570455 DOI: 10.1002/(sici)1096-9861(19991227)415:4<449::aid-cne3>3.0.co;2-u] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A cDNA clone (lobGRK2) encoding a protein of 690 amino acids with significant similarity to the GRK2 subfamily of G-protein coupled receptor kinases was isolated. lobGRK2 was widely expressed as a 9-kb major transcript and a protein of 80 kDa. It was most abundant in the brain and the olfactory organ but was absent in the eye/eyestalk. Immunocytochemistry revealed lobGRK2 immunoreactivity in the outer dendritic segments of the olfactory receptor neurons, the site of olfactory transduction. LobGRK2 immunoreactivity was observed in most neuronal structures in the brain, although with varying intensity. It was strongest in neuropil, especially the olfactory and accessory lobes but was also detectable in neuronal cell bodies. Stimulation of brain homogenates with a mixture of neurotransmitters increased the association of lobGRK2 with membranes and with G(beta). Similarly, stimulation of olfactory dendrite homogenates with an odorant mixture caused lobGRK2 to associate with G(beta). These results support the conclusion that lobGRK2 responds to odorants and to neurotransmitters and may act to initiate desensitization by phosphorylating G-protein-coupled receptors in the olfactory organ and the brain, respectively.
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Affiliation(s)
- F Xu
- Department of Physiology, University of Kentucky College of Medicine, Lexington, Kentucky, 40536-0298, USA
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