Torgerson R R, McNiven M A
Department of Biochemistry and Molecular Biology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
J Cell Physiol. 2000 Mar;182(3):438-47. doi: 10.1002/(SICI)1097-4652(200003)182:3<438::AID-JCP15>3.0.CO;2-N.
The actin cytoskeleton plays an important role in the mediation of exocytosis and the determination of cell shape. Experimentally induced changes in cell shape have been shown to affect stimulated secretion in pancreatic acini. In this study, we have examined whether physiologic agonists induce changes in acinar cell shape to modulate secretion. Computer-enhanced video microscopy, immunofluorescence confocal microscopy, and quantitative Western blotting were used to study cell shape changes and cytoskeletal dynamics in rat pancreatic acini. Amylase assays were performed to study the effect of the actin-myosin cytoskeletal antagonists latrunculin A, BDM, and ML-9 on secretion. We found that pancreatic acini underwent a prominent and reversible shape change in response to the physiologic secretory agonist cholecystokinin. This was accompanied by an apical activation of myosin II as well as a basolateral redistribution of both actin and myosin II. Cytoskeletal antagonists inhibited this shape change and attenuated stimulated amylase secretion. Therefore, in addition to acting as a barrier at the apex, the actin-myosin cytoskeleton may also function to modulate cell shape to further regulate stimulated secretion.
肌动蛋白细胞骨架在胞吐作用的介导以及细胞形状的决定中发挥着重要作用。实验诱导的细胞形状变化已被证明会影响胰腺腺泡的刺激分泌。在本研究中，我们研究了生理性激动剂是否会诱导腺泡细胞形状变化以调节分泌。使用计算机增强视频显微镜、免疫荧光共聚焦显微镜和定量蛋白质免疫印迹法来研究大鼠胰腺腺泡中的细胞形状变化和细胞骨架动力学。进行淀粉酶测定以研究肌动蛋白 - 肌球蛋白细胞骨架拮抗剂拉特肌毒素A、BDM和ML - 9对分泌的影响。我们发现，胰腺腺泡对生理性分泌激动剂胆囊收缩素会发生显著且可逆的形状变化。这伴随着肌球蛋白II的顶端激活以及肌动蛋白和肌球蛋白II的基底外侧重新分布。细胞骨架拮抗剂抑制了这种形状变化并减弱了刺激的淀粉酶分泌。因此，除了在顶端作为屏障发挥作用外，肌动蛋白 - 肌球蛋白细胞骨架还可能起到调节细胞形状以进一步调节刺激分泌的作用。
