Myosin II and rho kinase activity are required for melanosome aggregation in fish retinal pigment epithelial cells
Myosin II and rho kinase activity are required for melanosome aggregation in fish retinal pigment epithelial cells
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DOI：
10.1002/cm.20231
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发表时间：
2007-11-01
影响因子：
--
通讯作者：
King-Smith, C.
中科院分区：
文献类型：
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作者：
Barsoum, I. B.;King-Smith, C.
在鱼的视网膜色素上皮（RPE）中，黑素体（色素颗粒）在光照下通过细胞体长距离迁移到顶端突起，并在黑暗中聚集回到细胞体中。RPE细胞可以从眼睛中分离、解离并在体外培养为单细胞。用cAMP或磷酸酶抑制剂冈田酸（OA）处理分离的RPE细胞，刺激黑素体聚集，而在多巴胺存在下cAMP或OA洗脱触发分散。以往的研究表明，肌动蛋白丝是必要的和足够的黑素体的聚集和分散的顶端突出的孤立的RPE。使用肌球蛋白II抑制剂blebbistatin和特异性rho激酶（ROCK）抑制剂H-1152研究肌球蛋白II在黑素小体运动中的作用。Blebbistatin和H-1152部分阻断了在分离的、分离的RPE细胞和分离的RPE片中由cAMP引发的黑素体聚集。相反，两种药物都不影响黑素体分散。在暴露于blebbistatin或H-1152的细胞中，然后使用OA触发聚集，黑素体聚集被完全抑制。这些结果表明：（1）黑素体聚集和分散是通过不同的肌动蛋白依赖性机制发生的;（2）黑素体完全聚集需要肌球蛋白II和ROCK活性，而不是分散;（3）尽管肌球蛋白II或ROCK抑制，但仍发生部分聚集，这表明聚集的第二组分依赖于cAMP信号传导，但不依赖于ROCK和肌球蛋白II。
In the retinal pigment epithelium (RPE) of fish, melanosomes (pigment granules) migrate long distances through the cell body into apical projections in the light, and aggregate back into the cell body in the dark. RPE cells can be isolated from the eye, dissociated, and cultured as single cells in vitro. Treatment of isolated RPE cells with cAMP or the phosphatase inhibitor, okadaic acid (OA), stimulates melanosome aggregation, while cAMP or OA washout in the presence of dopamine triggers dispersion. Previous studies have shown that actin filaments are both necessary and sufficient for aggregation and dispersion of melanosomes within apical projections of isolated RPE. The role of myosin II in melanosome motility was investigated using the myosin II inhibitor, blebbistatin, and a specific rho kinase (ROCK) inhibitor, H-1152. Blebbistatin and H-1152 partially blocked melanosome aggregation triggered by cAMP in dissociated, isolated RPE cells and isolated sheets of RPE. In contrast, neither drug affected melanosome dispersion. In cells exposed to either blebbistatin or H-1152, then triggered to aggregate using OA, melanosome aggregation was completely inhibited. These results demonstrate that (1) melanosome aggregation and dispersion occur through different, actin-dependent mechanisms; (2) myosin II and ROCK activity are required for full melanosome aggregation, but not dispersion; (3) partial aggregation that occurred despite myosin II or ROCK inhibition suggests a second component of aggregation that is dependent on cAMP signaling, but independent of ROCK and myosin II.