Lim Chinten J, Kain Kristin H, Tkachenko Eugene, Goldfinger Lawrence E, Gutierrez Edgar, Allen Michael D, Groisman Alex, Zhang Jin, Ginsberg Mark H
Department of Medicine, University of California San Diego, La Jolla, CA 92093-0726, USA.
Mol Biol Cell. 2008 Nov;19(11):4930-41. doi: 10.1091/mbc.e08-06-0564. Epub 2008 Sep 10.
cAMP-dependent protein kinase A (PKA) is important in processes requiring localized cell protrusion, such as cell migration and axonal path finding. Here, we used a membrane-targeted PKA biosensor to reveal activation of PKA at the leading edge of migrating cells. Previous studies show that PKA activity promotes protrusion and efficient cell migration. In live migrating cells, membrane-associated PKA activity was highest at the leading edge and required ligation of integrins such as alpha4beta1 or alpha5beta1 and an intact actin cytoskeleton. alpha4 integrins are type I PKA-specific A-kinase anchoring proteins, and we now find that type I PKA is important for localization of alpha4beta1 integrin-mediated PKA activation at the leading edge. Accumulation of 3' phosphorylated phosphoinositides [PtdIns(3,4,5)P(3)] products of phosphatidylinositol 3-kinase (PI3-kinase) is an early event in establishing the directionality of migration; however, polarized PKA activation did not require PI3-kinase activity. Conversely, inhibition of PKA blocked accumulation of a PtdIns(3,4,5)P(3)-binding protein, the AKT-pleckstrin homology (PH) domain, at the leading edge; hence, PKA is involved in maintaining cell polarity during migration. In sum, we have visualized compartment-specific PKA activation in migrating cells and used it to reveal that adhesion-mediated localized activation of PKA is an early step in directional cell migration.
环磷酸腺苷（cAMP）依赖性蛋白激酶A（PKA）在需要局部细胞突起的过程中很重要，比如细胞迁移和轴突寻路。在此，我们使用了一种膜靶向PKA生物传感器来揭示迁移细胞前缘PKA的激活情况。先前的研究表明，PKA活性可促进突起形成和高效的细胞迁移。在活的迁移细胞中，膜相关PKA活性在前缘最高，并且需要整合素如α4β1或α5β1的连接以及完整的肌动蛋白细胞骨架。α4整合素是I型PKA特异性的A激酶锚定蛋白，我们现在发现I型PKA对于α4β1整合素介导的PKA在前缘激活的定位很重要。磷脂酰肌醇3激酶（PI3激酶）的3'磷酸化磷酸肌醇[PtdIns(3,4,5)P(3)]产物的积累是建立迁移方向性的早期事件；然而，极化PKA激活并不需要PI3激酶活性。相反，抑制PKA会阻止一种PtdIns(3,4,5)P(3)结合蛋白——AKT-普列克底物蛋白同源（PH）结构域——在前缘的积累；因此，PKA参与了迁移过程中细胞极性的维持。总之，我们已经可视化了迁移细胞中特定区室的PKA激活，并利用它揭示了黏附介导的PKA局部激活是定向细胞迁移的早期步骤。
