YAP Nuclear Localization in the Absence of Cell-Cell Contact Is Mediated by a Filamentous Actin-dependent, Myosin II- and Phospho-YAP-independent Pathway during Extracellular Matrix Mechanosensing
YAP Nuclear Localization in the Absence of Cell-Cell Contact Is Mediated by a Filamentous Actin-dependent, Myosin II- and Phospho-YAP-independent Pathway during Extracellular Matrix Mechanosensing
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DOI：
10.1074/jbc.m115.708313
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发表时间：
2016-03-18
影响因子：
4.8
通讯作者：
Waterman, Clare M.
中科院分区：
文献类型：
--
作者：
Das, Arupratan;Fischer, Robert S.;Waterman, Clare M.
细胞-细胞接触抑制和细胞的机械环境都被证明可以调节YAP核定位，从而调节细胞增殖。基因、药理学和基质刚度扰动引起的细胞收缩性变化调节YAP核定位。然而，由于收缩性和f -肌动蛋白组织是相互关联的细胞骨架特性，目前尚不清楚其中哪一个明显调节YAP的定位。在这里，我们发现在没有细胞间接触的情况下，肌动球蛋白的收缩性抑制了YAP在Ser位点的磷酸化（112），然而，收缩性的丧失和YAP磷酸化的增加都不足以使其核排斥。我们发现肌动蛋白细胞骨架完整性对于YAP核定位至关重要，并且可以超越磷酸化调控或收缩性介导的YAP核定位调控。这种肌动蛋白介导的调控在机械转导过程中是保守的，因为底物的依从性增加了YAP的磷酸化，降低了细胞骨架的完整性，导致细胞核排斥YAP和Ser(P)(112)-YAP。这些数据为YAP调控的两种肌动蛋白介导途径提供了证据；其中一种是肌动球蛋白收缩性调节YAP磷酸化，另一种是细胞骨架完整性介导的YAP核定位的独立于收缩性的调节。我们认为，在非接触抑制细胞中，后一种机制可能在低刚度状态下很重要，例如在生理环境中可能遇到的情况。
Cell-cell contact inhibition and the mechanical environment of cells have both been shown to regulate YAP nuclear localization to modulate cell proliferation. Changes in cellular contractility by genetic, pharmacological, and matrix stiffness perturbations regulate YAP nuclear localization. However, because contractility and F-actin organization are interconnected cytoskeletal properties, it remains unclear which of these distinctly regulates YAP localization. Here we show that in the absence of cell-cell contact, actomyosin contractility suppresses YAP phosphorylation at Ser(112), however, neither loss of contractility nor increase in YAP phosphorylation is sufficient for its nuclear exclusion. We find that actin cytoskeletal integrity is essential for YAP nuclear localization, and can override phosphoregulation or contractility-mediated regulation of YAP nuclear localization. This actin-mediated regulation is conserved during mechanotransduction, as substrate compliance increased YAP phosphorylation and reduced cytoskeletal integrity leading to nuclear exclusion of both YAP and Ser(P)(112)-YAP. These data provide evidence for two actin-mediated pathways for YAP regulation; one in which actomyosin contractility regulates YAP phosphorylation, and a second that involves cytoskeletal integrity-mediated regulation of YAP nuclear localization independent of contractility. We suggest that in non-contact inhibited cells, this latter mechanism may be important in low stiffness regimes, such as may be encountered in physiological environments.