Carbachol-mediated pigment granule dispersion in retinal pigment epithelium requires Ca<sup>2+ </sup>and calcineurin
<p>Abstract</p> <p>Background</p> <p>Inside bluegill (<it>Lepomis macrochirus</it>) retinal pigment epithelial cells, pigment granules move in response to extracellular signals. During the process of aggregation, pigment motility is directed toward the cell...
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| Format: | Article |
| Language: | English |
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BMC
2007-12-01
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| Series: | BMC Cell Biology |
| Online Access: | http://www.biomedcentral.com/1471-2121/8/53 |
| _version_ | 1818662435037380608 |
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| author | García Dana M Johnson Adam S |
| author_facet | García Dana M Johnson Adam S |
| author_sort | García Dana M |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Inside bluegill (<it>Lepomis macrochirus</it>) retinal pigment epithelial cells, pigment granules move in response to extracellular signals. During the process of aggregation, pigment motility is directed toward the cell nucleus; in dispersion, pigment is directed away from the nucleus and into long apical processes. A number of different chemicals have been found to initiate dispersion, and carbachol (an acetylcholine analog) is one example. Previous research indicates that the carbachol-receptor interaction activates a G<sub>q</sub>-mediated pathway which is commonly linked to Ca<sup>2+ </sup>mobilization. The purpose of the present study was to test for involvement of calcium and to probe calcium-dependent mediators to reveal their role in carbachol-mediated dispersion.</p> <p>Results</p> <p>Carbachol-induced pigment granule dispersion was blocked by the calcium chelator BAPTA. In contrast, the calcium channel antagonist verapamil, and incubation in Ca<sup>2+</sup>-free medium failed to block carbachol-induced dispersion. The calcineurin inhibitor cypermethrin blocked carbachol-induced dispersion; whereas, two protein kinase C inhibitors (staurosporine and bisindolylmaleimide II) failed to block carbachol-induced dispersion, and the protein kinase C activator phorbol 12-myristate 13-acetate failed to elicit dispersion.</p> <p>Conclusion</p> <p>A rise in intracellular calcium is necessary for carbachol-induced dispersion; however, the Ca<sup>2+ </sup>requirement is not dependent on extracellular sources, implying that intracellular stores are sufficient to enable pigment granule dispersion to occur. Calcineurin is a likely Ca<sup>2+</sup>-dependent mediator involved in the signal cascade. Although the pathway leads to the generation of diacylglycerol and calcium (both required for the activation of certain PKC isoforms), our evidence does not support a significant role for PKC.</p> |
| first_indexed | 2024-12-17T05:00:54Z |
| format | Article |
| id | doaj.art-72043518ad7d4a99ba1186378583a07b |
| institution | Directory Open Access Journal |
| issn | 1471-2121 |
| language | English |
| last_indexed | 2024-12-17T05:00:54Z |
| publishDate | 2007-12-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Cell Biology |
| spelling | doaj.art-72043518ad7d4a99ba1186378583a07b2022-12-21T22:02:33ZengBMCBMC Cell Biology1471-21212007-12-01815310.1186/1471-2121-8-53Carbachol-mediated pigment granule dispersion in retinal pigment epithelium requires Ca<sup>2+ </sup>and calcineurinGarcía Dana MJohnson Adam S<p>Abstract</p> <p>Background</p> <p>Inside bluegill (<it>Lepomis macrochirus</it>) retinal pigment epithelial cells, pigment granules move in response to extracellular signals. During the process of aggregation, pigment motility is directed toward the cell nucleus; in dispersion, pigment is directed away from the nucleus and into long apical processes. A number of different chemicals have been found to initiate dispersion, and carbachol (an acetylcholine analog) is one example. Previous research indicates that the carbachol-receptor interaction activates a G<sub>q</sub>-mediated pathway which is commonly linked to Ca<sup>2+ </sup>mobilization. The purpose of the present study was to test for involvement of calcium and to probe calcium-dependent mediators to reveal their role in carbachol-mediated dispersion.</p> <p>Results</p> <p>Carbachol-induced pigment granule dispersion was blocked by the calcium chelator BAPTA. In contrast, the calcium channel antagonist verapamil, and incubation in Ca<sup>2+</sup>-free medium failed to block carbachol-induced dispersion. The calcineurin inhibitor cypermethrin blocked carbachol-induced dispersion; whereas, two protein kinase C inhibitors (staurosporine and bisindolylmaleimide II) failed to block carbachol-induced dispersion, and the protein kinase C activator phorbol 12-myristate 13-acetate failed to elicit dispersion.</p> <p>Conclusion</p> <p>A rise in intracellular calcium is necessary for carbachol-induced dispersion; however, the Ca<sup>2+ </sup>requirement is not dependent on extracellular sources, implying that intracellular stores are sufficient to enable pigment granule dispersion to occur. Calcineurin is a likely Ca<sup>2+</sup>-dependent mediator involved in the signal cascade. Although the pathway leads to the generation of diacylglycerol and calcium (both required for the activation of certain PKC isoforms), our evidence does not support a significant role for PKC.</p>http://www.biomedcentral.com/1471-2121/8/53 |
| spellingShingle | García Dana M Johnson Adam S Carbachol-mediated pigment granule dispersion in retinal pigment epithelium requires Ca<sup>2+ </sup>and calcineurin BMC Cell Biology |
| title | Carbachol-mediated pigment granule dispersion in retinal pigment epithelium requires Ca<sup>2+ </sup>and calcineurin |
| title_full | Carbachol-mediated pigment granule dispersion in retinal pigment epithelium requires Ca<sup>2+ </sup>and calcineurin |
| title_fullStr | Carbachol-mediated pigment granule dispersion in retinal pigment epithelium requires Ca<sup>2+ </sup>and calcineurin |
| title_full_unstemmed | Carbachol-mediated pigment granule dispersion in retinal pigment epithelium requires Ca<sup>2+ </sup>and calcineurin |
| title_short | Carbachol-mediated pigment granule dispersion in retinal pigment epithelium requires Ca<sup>2+ </sup>and calcineurin |
| title_sort | carbachol mediated pigment granule dispersion in retinal pigment epithelium requires ca sup 2 sup and calcineurin |
| url | http://www.biomedcentral.com/1471-2121/8/53 |
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