Action of Light on Frog Pigment Cells in Culture

Daniolos, Athena; Lerner, Aaron B.; Lerner, Michael R.

doi:10.1111/j.1600-0749.1990.tb00260.x

Cited by 154 publications

(139 citation statements)

References 40 publications

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“…This process is called "dispersion." Cultured melanophores treated with α-melanocyte-stimulating hormone experience a burst of cAMP levels, which in turn activates PKA and leads to the dispersion of melanosomes on the actin network, a process responsible for the darkening the animal's skin color (36)(37)(38). The opposite process occurs during aggregation, when cAMP levels are reduced and melanosomes are transferred from the actin to the microtubule network to be clustered in the cell center (36,38,39).…”

Section: Significancementioning

confidence: 99%

Myosin Va’s adaptor protein melanophilin enforces track selection on the microtubule and actin networks in vitro

Oberhofer

Spieler

Rosenfeld

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Pigment organelles, or melanosomes, are transported by kinesin, dynein, and myosin motors. As such, melanosome transport is an excellent model system to study the functional relationship between the microtubule-and actin-based transport systems. In mammalian melanocytes, it is well known that the Rab27a/melanophilin/myosin Va complex mediates actin-based transport in vivo. However, pathways that regulate the overall directionality of melanosomes on the actin/microtubule networks have not yet been delineated. Here, we investigated the role of PKA-dependent phosphorylation on the activity of the actin-based Rab27a/melanophilin/myosin Va transport complex in vitro. We found that melanophilin, specifically its C-terminal actin-binding domain (ABD), is a target of PKA. Notably, in vitro phosphorylation of the ABD closely recapitulated the previously described in vivo phosphorylation pattern. Unexpectedly, we found that phosphorylation of the ABD affected neither the interaction of the complex with actin nor its movement along actin tracks. Surprisingly, the phosphorylation state of melanophilin was instead important for reversible association with microtubules in vitro. Dephosphorylated melanophilin preferred binding to microtubules even in the presence of actin, whereas phosphorylated melanophilin associated with actin. Indeed, when actin and microtubules were present simultaneously, melanophilin's phosphorylation state enforced track selection of the Rab27a/melanophilin/ myosin Va transport complex. Collectively, our results unmasked the regulatory dominance of the melanophilin adaptor protein over its associated motor and offer an unexpected mechanism by which filaments of the cytoskeletal network compete for the moving organelles to accomplish directional transport on the cytoskeleton in vivo.melanophilin | myosin Va | intracellular transport | transport regulation

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Section: Significancementioning

confidence: 99%

Myosin Va’s adaptor protein melanophilin enforces track selection on the microtubule and actin networks in vitro

Oberhofer

Spieler

Rosenfeld

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…Conversely, agonist activation of a recombinant G~-coupledGPCR expressed heterologously in melanophores will lead to pigment aggregation. Changes in melanophore pigmentation show a dosedependent correlation with the level of specific receptor activation and can be quantified by the change in absorbance at 600 nm between the nonactivated and agonist-activated cells (Daniolos et al, 1990;Potenza et a!., 1992;Lerner, 1994).…”

Section: Signal Transduction Pathway Of Human Galr2 and Galr3mentioning

confidence: 99%

“…Because rat GALR2 would appear to couple to both G 1-and Gqc oupled signaling pathways, we chose to investigate the signaling mechanism of human GALR2 in Xenopus melanophores (Daniolos et a!., 1990;Potenza et al, 1992;Lerner, 1994). The melanophore assay system is based on the dispersion and aggregation of intracellular pigment granules in response to changes in intracellular second messenger molecules.…”

Section: Signal Transduction Pathway Of Human Galr2 and Galr3mentioning

confidence: 99%

Molecular Characterization and Expression of Cloned Human Galanin Receptors GALR2 and GALR3

Kolakowski

O’Neill

Howard

et al. 1998

Journal of Neurochemistry

169

129

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Abstract:Galanin is a 29-or 30-amino acid peptide with wide-ranging effects on hormone release, feeding behavior, smooth muscle contractility, and somatosensory neuronal function. Three distinct galanin receptor (GALR) subtypes, designated GALR1, 2, and 3, have been cloned from the rat. We report here the cloning of the human GALR2 and GALR3 genes, an initial characterization of their pharmacology with respect to radioligand binding and signal transduction pathways, and a profile of their expression in brain and peripheral tissues. Human GALR2 and GALR3 show, respectively, 92 and 89% amino acid sequence identity with their rat homologues. Radioligand binding studies with 125l-galanin show that recombinant human GALR2 binds with high affinity to human galanin (K 0 = 0.3 nM). Human GALR3 binds galanin with less affinity (IC50 of 12 nM for porcine galanin and 75 nM for human galanin). Human GALR2 was shown to couple to phospholipase C and elevation of intracellular calcium levels as assessed by aequorin luminescence in HEK-293 cells and by Xenopus melanophore pigment aggregation and dispersion assays, in contrast to human GALR1 and human GALR3, which signal predominantly through inhibition of adenylate cyclase. GALR2 mRNA shows a wide distribution in the brain (mammillary nuclei, dentate gyrus, cingulate gyrus, and posterior hypothalamic, supraoptic, and arcuate nuclei), and restricted peripheral tissue distritution with highest mRNA levels detected in human small intestine. In comparison, whereas GALR3 mRNA was expressed in many areas of the rat brain, there was abundant expression in the primary 01-factory cortex, olfactory tubercie, the islands of Calleja, the hippocampal CA regions of Ammon's horn, and the dentate gyrus. GALR3 mRNA was highly expressed in human testis and was detectable in adrenal gland and pancreas. The genes for human GALR2 and 3 were localized to chromosomes 17q25 and 22q12.2-13.1, respectively. Key Words: Galanin receptor-G protein-coupled receptor-Cloning.

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“…The maximal concentration of solvent was 1% v v 71 which did not cause pigment redistribution in melanophores (data not shown). As light has been shown to cause pigment dispersion (Daniolos et al, 1990), melanophores were kept in the dark during drug treatment. As 5-HT could potentially be oxidized and/or its eective concentration diminished as a result of uptake and metabolism by cells, in a preliminary experiment an antioxidant, ascorbic acid (10 76 M), a 5-HTuptake inhibitor, imipramine (10 75 M) and a monoamine oxidase inhibitor, pargyline (10 75 M) were added to the 0.76L-15 medium used for drug dilution.…”

Section: Quantification Of Melanosome Translocationmentioning

confidence: 99%

“…A Xenopus laevis melanophore clonal cell line (Daniolos et al, 1990), provided by Dr M.R. Lerner (University of Texas, Dallas, U.S.A.), was grown as previously described in 96-well cell culture plates and was used at a density of 6000 ± 8000 melanophores/well (Teh & Sugden, 1999).…”

Section: Quantification Of Melanosome Translocationmentioning

confidence: 99%

An endogenous 5‐HT₇ receptor mediates pigment granule dispersion in Xenopus laevis melanophores

Teh

Sugden

2001

British J Pharmacology

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1 Melatonin (5-methoxy N-acetyltryptamine) and serotonin (5-HT) exert rapid, but opposite eects on pigment granule distribution in Xenopus laevis melanophores. Low concentrations of melatonin (10 711 ± 10 79 M) cause a dramatic perinuclear aggregation of the melanin-containing granules, while 5-HT (10 78 ± 10 75 M) disperses pigment granules throughout the cell. 2 The present study found that pharmacological doses of melatonin (510 76 M) induced a timeand concentration-dependent pigment granule dispersion, which was mediated by an endogenous melanophore 5-HT receptor. (54)] was also consistent with an action on 5-HT 7 receptors. 5 RT ± PCR con®rmed that melanophores express 5-HT 7 receptor mRNA. The pigment dispersing eect of high melatonin concentrations in melanophores is most likely mediated by activation of 5-HT 7 receptors. Conceivably some of the eects attributed to pharmacological doses of melatonin in mammals may be mediated by activation of 5-HT 7 receptors.

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Action of Light on Frog Pigment Cells in Culture

Cited by 154 publications

References 40 publications

Myosin Va’s adaptor protein melanophilin enforces track selection on the microtubule and actin networks in vitro

Myosin Va’s adaptor protein melanophilin enforces track selection on the microtubule and actin networks in vitro

Molecular Characterization and Expression of Cloned Human Galanin Receptors GALR2 and GALR3

An endogenous 5‐HT₇ receptor mediates pigment granule dispersion in Xenopus laevis melanophores

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Action of Light on Frog Pigment Cells in Culture

Cited by 154 publications

References 40 publications

Myosin Va’s adaptor protein melanophilin enforces track selection on the microtubule and actin networks in vitro

Myosin Va’s adaptor protein melanophilin enforces track selection on the microtubule and actin networks in vitro

Molecular Characterization and Expression of Cloned Human Galanin Receptors GALR2 and GALR3

An endogenous 5‐HT7 receptor mediates pigment granule dispersion in Xenopus laevis melanophores

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An endogenous 5‐HT₇ receptor mediates pigment granule dispersion in Xenopus laevis melanophores