Regulation of macropinocytosis by p21-activated kinase-1
Regulation of macropinocytosis by p21-activated kinase-1
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DOI：
10.1091/mbc.11.10.3341
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发表时间：
2000-10-01
影响因子：
3.3
通讯作者：
Bokoch, GM
中科院分区：
文献类型：
--
作者：
Dharmawardhane, S;Schürmann, A;Bokoch, GM
巨胞饮过程是正常细胞功能的一个重要方面，有助于细胞的生长和运动过程，p21激活的激酶（PAK）是活化的Pac和Cdc 42鸟苷5 '-三磷酸酶的靶点，并且已经显示出调节肌动蛋白-肌球蛋白细胞骨架。Ln成纤维细胞PAK 1定位于膜皱褶区域，以及阿米洛利敏感的胞饮小泡。PAK 1激酶自抑制结构域的表达阻断了血小板源性生长因子和RacQ 61 L刺激的70 kDa葡聚糖颗粒的摄取，而该结构域的非活性版本则没有，表明PAK激酶活性是正常生长因子诱导的巨胞饮所必需的。PAK调节巨胞饮作用的机制在表达各种PAK 1构建体的NIH 3 T3细胞系中进行了研究，这些构建体在四环素反应性反式激活因子的控制下。细胞表达PAK 1（H83，86 L），突变体，显着刺激背膜皱褶的形成，表现出增加巨胞饮摄取的70 kDa的葡聚糖颗粒在没有额外的刺激。显性负性Rac 1-T17 N的共表达不能拮抗这种效应。在血小板衍生生长因子的存在下，PAK 1（H83，86 L）和高激酶活性的PAK 1（T423 E）突变体显着增强了70-kDa葡聚糖的摄取。野生型PAK 1和载体对照均未表现出增强的巨胞饮作用，PAK 1（H83，86 L）也未影响网格蛋白依赖性内吞机制。PAK 1的活性版本增强了生长因子刺激的70-kDa葡聚糖的摄取和流出，表明PAK 1活性调节胞饮小泡循环。这些数据表明，PAK 1在巨胞饮过程中起着重要的调节作用，可能与PAK在定向细胞运动中的需要有关。
The process of macropinocytosis is an essential aspect of normal cell function, contributing to both growth and motile processes of cells, p21-activated kinases (PAKs) are targets for activated Pac and Cdc42 guanosine 5'-triphosphatases and have been shown to regulate the actin-myosin cytoskeleton. Ln fibroblasts PAK1 localizes to areas of membrane ruffling, as well as to amiloride-sensitive pinocytic vesicles. Expression of a PAK1 kinase autoinhibitory domain blocked both platelet-derived growth factor- and RacQ61L-stimulated uptake of 70-kDa dextran particles, whereas an inactive version of this domain did not, indicating that PAK kinase activity is required for normal growth factor-induced macropinocytosis. The mechanisms by which PAK modulate macropinocytosis were examined in NIH3T3 cell lines expressing various PAK1 constructs under the control of a tetracycline-responsive transactivator. Cells expressing PAK1 (H83,86L), a mutant that dramatically stimulates formation of dorsal membrane ruffles, exhibited increased macropinocytic uptake of 70-kDa dextran particles in the absence of additional stimulation. This effect was not antagonized by coexpression of dominant-negative Rac1-T17N. In the presence of platelet-derived growth factor, both PAK1 (H83,86L) and a highly kinase active PAK1 (T423E) mutant dramatically enhanced the uptake of 70-kDa dextran. Neither wild-type PAK1 nor vector controls exhibited enhanced macropinocytosis, nor did PAK1 (H83,86L) affect clathrin-dependent endocytic mechanisms. Active versions of PAK1 enhanced both growth factor-stimulated 70-kDa dextran uptake and efflux, suggesting that PAK1 activity modulated pinocytic vesicle cycling. These data indicate that PAK1 plays an important regulatory role in the process of macropinocytosis, perhaps related to the requirement for PAK in directed cell motility.