Sonoda Hirofumi, Okada Taro, Jahangeer Saleem, Nakamura Shun-ichi
Division of Biochemistry, Department of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Kobe, Japan.
J Biol Chem. 2007 Nov 23;282(47):34085-92. doi: 10.1074/jbc.M705593200. Epub 2007 Sep 26.
Although organelles such as the endoplasmic reticulum and Golgi apparatus are highly compartmentalized, these organelles are interconnected through a network of vesicular trafficking. The marine sponge metabolite ilimaquinone (IQ) is known to induce Golgi membrane fragmentation and is widely used to study the mechanism of vesicular trafficking. Although IQ treatment causes protein kinase D (PKD) activation, the detailed mechanism of IQ-induced Golgi membrane fragmentation remains unclear. In this work, we found that IQ treatment of cells caused a robust activation of phospholipase D (PLD). In the presence of 1-butanol but not 2-butanol, IQ-induced Golgi membrane fragmentation was completely blocked. In addition, IQ failed to induce Golgi membrane fragmentation in PLD knock-out DT40 cells. Furthermore, IQ-induced PKD activation was completely blocked by treatment with either 1-butanol or propranolol. Notably, IQ-induced Golgi membrane fragmentation was also blocked by propranolol treatment. These results indicate that PLD-catalyzed formation of phosphatidic acid is a prerequisite for IQ-induced Golgi membrane fragmentation and that enzymatic conversion of phosphatidic acid to diacylglycerol is necessary for subsequent activation of PKD and IQ-induced Golgi membrane fragmentation.
尽管内质网和高尔基体等细胞器高度区室化，但这些细胞器通过囊泡运输网络相互连接。海洋海绵代谢物伊立马醌（IQ）已知可诱导高尔基体膜碎片化，并被广泛用于研究囊泡运输机制。尽管IQ处理会导致蛋白激酶D（PKD）激活，但IQ诱导高尔基体膜碎片化的详细机制仍不清楚。在这项研究中，我们发现用IQ处理细胞会导致磷脂酶D（PLD）的强烈激活。在存在1-丁醇而非2-丁醇的情况下，IQ诱导的高尔基体膜碎片化被完全阻断。此外，IQ在PLD基因敲除的DT40细胞中未能诱导高尔基体膜碎片化。此外，用1-丁醇或普萘洛尔处理可完全阻断IQ诱导的PKD激活。值得注意的是，用普萘洛尔处理也可阻断IQ诱导的高尔基体膜碎片化。这些结果表明，PLD催化形成磷脂酸是IQ诱导高尔基体膜碎片化的先决条件，并且磷脂酸向二酰甘油的酶促转化对于随后PKD的激活和IQ诱导的高尔基体膜碎片化是必要的。
