Institute of Cell Biology and Immunology, University of Stuttgart, 70569 Stuttgart, Germany.
Mol Biol Cell. 2013 Feb;24(3):222-33. doi: 10.1091/mbc.E12-03-0198. Epub 2012 Dec 14.
Before entering mitosis, the stacks of the Golgi cisternae are separated from each other, and inhibiting this process delays entry of mammalian cells into mitosis. Protein kinase D (PKD) is known to be involved in Golgi-to-cell surface transport by controlling the biogenesis of specific transport carriers. Here we show that depletion of PKD1 and PKD2 proteins from HeLa cells by small interfering RNA leads to the accumulation of cells in the G2 phase of the cell cycle and prevents cells from entering mitosis. We further provide evidence that inhibition of PKD blocks mitotic Raf-1 and mitogen-activated protein kinase kinase (MEK) activation, and, as a consequence, mitotic Golgi fragmentation, which could be rescued by expression of active MEK1. Finally, Golgi fluorescence recovery after photobleaching analyses demonstrate that PKD is crucial for the cleavage of the noncompact zones of Golgi membranes in G2 phase. Our findings suggest that PKD controls interstack Golgi connections in a Raf-1/MEK1-dependent manner, a process required for entry of the cells into mitosis.
在进入有丝分裂之前，高尔基池的堆叠物彼此分离，抑制这个过程会延迟哺乳动物细胞进入有丝分裂。已知蛋白激酶 D (PKD) 通过控制特定运输载体的生物发生参与高尔基体到细胞表面的运输。在这里，我们表明通过小干扰 RNA 从 HeLa 细胞中耗尽 PKD1 和 PKD2 蛋白会导致细胞在细胞周期的 G2 期积累，并阻止细胞进入有丝分裂。我们进一步提供证据表明，PKD 的抑制会阻断有丝分裂 Raf-1 和丝裂原激活的蛋白激酶激酶（MEK）的激活，因此，有丝分裂时高尔基体碎片化，可以通过表达活性 MEK1 来挽救。最后，光漂白后荧光恢复分析表明 PKD 对于 G2 期非致密区高尔基体膜的裂解至关重要。我们的研究结果表明，PKD 以 Raf-1/MEK1 依赖的方式控制堆栈之间的高尔基体连接，这是细胞进入有丝分裂所必需的过程。
