Rasip1-Mediated Rho GTPase Signaling Regulates Blood Vessel Tubulogenesis via Nonmuscle Myosin II.
Rasip1-Mediated Rho GTPase Signaling Regulates Blood Vessel Tubulogenesis via Nonmuscle Myosin II.
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DOI：
10.1161/circresaha.116.309094
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发表时间：
2016-09-16
影响因子：
20.1
通讯作者：
Cleaver O
中科院分区：
文献类型：
--
作者：
Barry DM;Koo Y;Norden PR;Wylie LA;Xu K;Wichaidit C;Azizoglu DB;Zheng Y;Cobb MH;Davis GE;Cleaver O
血管小管的形成对心血管的发育至关重要。在内皮细胞（ECs）的初始血管索内，顶端膜形成并清除细胞间连接，从而允许连续的中央管腔打开。Rasip1是根尖连接清除和调控Rho GTPase活性所必需的。然而，目前尚不清楚不同Rho gtpase的活性如何通过Rasip1协调来指导微管发生。本研究的目的是确定Rasip1下游驱动血管小管形成的机制。使用条件小鼠突变模型和药理学方法，我们剖析了GTPase在Rasip1下游的途径。我们发现在血管小管形成过程中EC顶端连接的清除依赖于Ras相互作用蛋白1 (Rasip1)，以及GTPase Cdc42和激酶Pak4。基因缺失的Rasip1或Cdc42，或Pak4的抑制，都能阻断EC的小管发生。相反，RhoA信号的失活导致血管过度扩张，暗示肌动球蛋白收缩性控制管腔直径。有趣的是，在管腔形态发生之前或之后，NMII的阻断活性会导致显着不同的小管发生表型，这表明其作用依赖于时间。Rasip1控制不同的gtpase库，这些gtpase库反过来调节不同的NMII库，以协调血管小管形成过程中的连接清除（重塑）和肌动球蛋白收缩。Rasip1促进Cdc42激活Pak4，进而激活NMII，清除根尖连接。一旦管腔打开，Rasip1通过抑制Arhgap29的RhoA来抑制肌动球蛋白的收缩性，从而在胚胎生长过程中控制血管管腔的扩张。这些发现阐明了由Rasip1通过下游Rho GTPases和NMII调控的逐步过程。
Vascular tubulogenesis is essential to cardiovascular development. Within initial vascular cords of endothelial cells (ECs), apical membranes are established and become cleared of cell-cell junctions, thereby allowing continuous central lumens to open. Rasip1 is required for apical junction clearance, as well as for regulation of Rho GTPase activity. However, it remains unknown how activities of different Rho GTPases are coordinated by Rasip1 to direct tubulogenesis. The aim of this study is to determine the mechanisms downstream of Rasip1 that drive vascular tubulogenesis. Using conditional mouse mutant models and pharmacological approaches, we dissect GTPase pathways downstream of Rasip1. We show that clearance of EC apical junctions during vascular tubulogenesis depends on Ras interacting protein 1 (Rasip1), as well as the GTPase Cdc42 and the kinase Pak4. Genetic deletion of Rasip1 or Cdc42, or inhibition of Pak4, all block EC tubulogenesis. By contrast, inactivation of RhoA signaling leads to vessel overexpansion, implicating actomyosin contractility in control of lumen diameter. Interestingly, blocking activity of NMII either prior to, or after, lumen morphogenesis results in dramatically different tubulogenesis phenotypes, suggesting time-dependent roles. Rasip1 controls different pools of GTPases, which in turn regulate different pools of NMII to coordinate junction clearance (remodeling) and actomyosin contractility during vascular tubulogenesis. Rasip1 promotes activity of Cdc42 to activate Pak4, which in turn activates NMII, clearing apical junctions. Once lumens open, Rasip1 suppresses actomyosin contractility via inhibition of RhoA by Arhgap29, allowing controlled expansion of vessel lumens during embryonic growth. These findings elucidate the stepwise processes regulated by Rasip1 through downstream Rho GTPases and NMII.