Phosphatidic Acid-dependent Recruitment and Function of the Rac Activator DOCK1 during Dorsal Ruffle Formation*
Phosphatidic Acid-dependent Recruitment and Function of the Rac Activator DOCK1 during Dorsal Ruffle Formation*
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DOI：
10.1074/jbc.m112.410423
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发表时间：
2013-01
期刊：
影响因子：
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通讯作者：
F. Sanematsu;A. Nishikimi;Mayuki Watanabe;T. Hongu;Yoshihiko Tanaka;Y. Kanaho;J. Côté;Y. Fukui
中科院分区：
文献类型：
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作者：
F. Sanematsu;A. Nishikimi;Mayuki Watanabe;T. Hongu;Yoshihiko Tanaka;Y. Kanaho;J. Côté;Y. Fukui
背景：DOCK1是一种非典型的RAC激活剂。结果：PDGF受体的激活通过与磷脂酸结合，诱导DOCK1移位至背侧褶皱。这种相互作用的阻断会损害背部褶皱的形成，但不会损害外围褶皱的形成。结论：在背部褶皱形成过程中，磷脂酸是DOCK1的脂质锚。意义：识别了背部褶皱形成的一种新的调节机制。受体酪氨酸激酶的激活导致两种不同类型的质膜结构的形成：外周褶皱和背褶皱。虽然这两种褶皱的形成都需要激活小GTP酶Rac，但动力学上的差异表明，它们的褶皱形成有不同的调节机制。DOCK1和DOCK5是非典型的RAC激活剂，均在小鼠胚胎成纤维细胞(MEF)中表达。我们发现，尽管在MEF中，DOCK1和DOCK5协同调节了PDGF诱导的RAC激活和外周褶皱的形成，但DOCK1缺乏本身就损害了MEF的背部褶皱的形成。与DOCK5不同，DOCK1通过C端多元氨基酸簇与磷脂酸(PA)结合，并定位于背褶皱。当这种相互作用被阻断时，PDGF诱导的背部褶皱的形成严重受损。此外，我们发现，磷脂酶D，一种催化PA合成的酶，是PDGF诱导的背部而不是外围褶皱形成所必需的。这些结果表明，磷脂酶D-PA轴通过调节DOCK1的定位选择性地控制背部褶皱的形成。
Background: DOCK1 is an atypical Rac activator. Results: Activation of the PDGF receptor induces DOCK1 translocation to the dorsal ruffles through association with phosphatidic acid. Blocking of this interaction impairs dorsal, but not peripheral, ruffle formation. Conclusion: Phosphatidic acid acts as a lipid anchor for DOCK1 during dorsal ruffle formation. Significance: A novel regulatory mechanism for dorsal ruffle formation was identified. Activation of receptor tyrosine kinases leads to the formation of two different types of plasma membrane structures: peripheral ruffles and dorsal ruffles. Although the formation of both ruffle types requires activation of the small GTPase Rac, the difference in kinetics suggests that a distinct regulatory mechanism operates for their ruffle formation. DOCK1 and DOCK5 are atypical Rac activators and are both expressed in mouse embryonic fibroblasts (MEFs). We found that although PDGF-induced Rac activation and peripheral ruffle formation were coordinately regulated by DOCK1 and DOCK5 in MEFs, DOCK1 deficiency alone impaired dorsal ruffle formation in MEFs. Unlike DOCK5, DOCK1 bound to phosphatidic acid (PA) through the C-terminal polybasic amino acid cluster and was localized to dorsal ruffles. When this interaction was blocked, PDGF-induced dorsal ruffle formation was severely impaired. In addition, we show that phospholipase D, an enzyme that catalyzes PA synthesis, is required for PDGF-induced dorsal, but not peripheral, ruffle formation. These results indicate that the phospholipase D-PA axis selectively controls dorsal ruffle formation by regulating DOCK1 localization.