Vitale María L, Carbajal M Eloísa
Département de Pathologie et Biologie Cellulaire, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada.
J Histochem Cytochem. 2004 Apr;52(4):517-27. doi: 10.1177/002215540405200410.
We have shown that dopamine (DA), an inhibitor of prolactin secretion from anterior pituitary lactotrophs, stabilizes the cortical actin cytoskeleton. DA-induced cortical actin stabilization is accompanied by cytoplasmic actin cable disassembly and cell rounding up. Our aim was to identify the mechanisms involved in DA-induced stabilization of the lactotroph's actin cytoskeleton. Here we show that DA increased the association of myosin II with the cell cortex, suggesting that DA facilitates actin-myosin interaction to stabilize cortical actin filaments. This notion was supported by the finding that inhibitors of actin-myosin interaction blocked DA-evoked morphological responses. In addition, our results showed that DA-induced myosin association with the cell periphery may be mediated by inhibition of Rac1/Cdc42-dependent pathways, whereas, DA-induced cytoplasmic actin filament disassembly may be mediated by the inhibition of MLCK- and RhoA-dependent pathways. In conclusion, the present results provide evidence that myosin II is involved in the DA-induced remodeling of actin filaments in lactotrophs, and that DA-induced cortical actin filament assembly and stabilization involve the translocation of myosin II to the cell cortex. This effect requires, among other things, inhibition of the Rac1/Cdc42-dependent signaling pathway.
我们已经表明，多巴胺（DA）作为垂体前叶催乳素细胞分泌催乳素的抑制剂，可稳定皮质肌动蛋白细胞骨架。DA诱导的皮质肌动蛋白稳定伴随着细胞质肌动蛋白束的解体和细胞变圆。我们的目的是确定参与DA诱导催乳素细胞肌动蛋白细胞骨架稳定的机制。在此我们表明，DA增加了肌球蛋白II与细胞皮质的结合，这表明DA促进肌动蛋白 - 肌球蛋白相互作用以稳定皮质肌动蛋白丝。肌动蛋白 - 肌球蛋白相互作用抑制剂可阻断DA诱发的形态学反应，这一发现支持了这一观点。此外，我们的结果表明，DA诱导的肌球蛋白与细胞周边的结合可能是通过抑制Rac1/Cdc42依赖性途径介导的，而DA诱导的细胞质肌动蛋白丝解体可能是通过抑制MLCK和RhoA依赖性途径介导的。总之，目前的结果提供了证据，表明肌球蛋白II参与了DA诱导的催乳素细胞中肌动蛋白丝的重塑，并且DA诱导的皮质肌动蛋白丝组装和稳定涉及肌球蛋白II向细胞皮质的转位。除其他外，这种效应需要抑制Rac1/Cdc42依赖性信号通路。
