da Costa S R, Yarber F A, Zhang L, Sonee M, Hamm-Alvarez S F
Department of Pharmaceutical Sciences, University of Southern California, School of Pharmacy, Los Angeles, CA 90033, USA.
J Cell Sci. 1998 May;111 ( Pt 9):1267-76. doi: 10.1242/jcs.111.9.1267.
Stimulation of lacrimal acini with secretagogues such as carbachol initiates movement and fusion of acinar secretory vesicles with the apical plasma membrane, resulting in release of protein into the nascent tear fluid. Using rabbit lacrimal acini reconstituted in vitro from isolated cells, we have investigated the organization of the apical cytoskeleton and its role in stimulated secretion. Confocal microscopy revealed a microtubule array emanating from the apical region of the acini; the apical region was also enriched in microfilaments and (gamma)-tubulin. Cytokeratin-based intermediate filaments were apically concentrated, and also detected at the cell periphery. Neither confocal microscopy nor biochemical analysis revealed any reorganization of lumenal microfilaments or microtubules which might accompany carbachol-stimulated release of secretory proteins. However, major changes in the acinar microtubule array induced by taxol or nocodazole were correlated with inhibition of carbachol-dependent release of the secreted protein, beta-hexosaminidase. Major changes in lumenal microfilaments induced by jasplakinolide or cytochalasin D did not inhibit the carbachol-dependent release of beta-hexosaminidase; rather, release of beta-hexosaminidase from jasplakinolide- or cytochalasin D-treated carbachol-stimulated acini was markedly increased relative to the release from untreated stimulated acini. Our findings demonstrate that microtubules play a major role in stimulated lacrimal secretion, and suggest a contributory role for microfilaments.
用诸如卡巴胆碱等促分泌剂刺激泪腺腺泡，会引发腺泡分泌囊泡与顶端质膜的移动和融合，从而导致蛋白质释放到新生泪液中。我们利用从分离细胞体外重构的兔泪腺腺泡，研究了顶端细胞骨架的组织及其在刺激分泌中的作用。共聚焦显微镜显示，微管阵列从腺泡的顶端区域发出；顶端区域还富含微丝和γ-微管蛋白。基于细胞角蛋白的中间丝在顶端集中，并且在细胞周边也能检测到。共聚焦显微镜和生化分析均未发现可能伴随卡巴胆碱刺激分泌蛋白释放的管腔内微丝或微管的任何重组。然而，紫杉醇或诺考达唑诱导的腺泡微管阵列的主要变化与卡巴胆碱依赖性分泌蛋白β-己糖胺酶释放的抑制相关。茉莉素内酯或细胞松弛素D诱导的管腔内微丝的主要变化并未抑制卡巴胆碱依赖性β-己糖胺酶的释放；相反，与未处理的刺激腺泡相比，从经茉莉素内酯或细胞松弛素D处理的卡巴胆碱刺激的腺泡中β-己糖胺酶的释放明显增加。我们的研究结果表明，微管在刺激泪液分泌中起主要作用，并提示微丝起辅助作用。
