The Hippo signaling is instrumental in regulating organ size, regeneration, and carcinogenesis. The cytoskeleton emerges as a primary Hippo signaling modulator. Its structural alterations in response to environmental and intrinsic stimuli control Hippo signaling pathway activity. However, the precise mechanisms underlying the cytoskeleton regulation of Hippo signaling are not fully understood. RAP2 GTPase is known to mediate the mechanoresponses of Hippo signaling activating the core Hippo kinases LATS1/2 through MAP4Ks and MST1/2. Here we show the pivotal role of the reciprocal regulation between RAP2 GTPase and the cytoskeleton in Hippo signaling. RAP2 deletion undermines the responses of the Hippo pathway to external cues tied to RhoA GTPase inhibition and actin cytoskeleton remodeling, such as energy stress and serum deprivation. Notably, RhoA inhibitors and actin disruptors fail to activate LATS1/2 effectively in RAP2-deficient cells. RNA sequencing highlighted differential regulation of both actin and microtubule networks by RAP2 gene deletion. Consistently, Taxol, a microtubule-stabilizing agent, was less effective in activating LATS1/2 and inhibiting cell growth in RAP2 and MAP4K4/6/7 knockout cells. In summary, our findings position RAP2 as a central integrator of cytoskeletal signals for Hippo signaling, which offers new avenues for understanding Hippo regulation and therapeutic interventions in Hippo-impaired cancers.

中文翻译：

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RAP2 GTPase 与细胞骨架在 Hippo 通路调节中的相互作用


Hippo 信号传导有助于调节器官大小、再生和癌变。细胞骨架作为主要的 Hippo 信号调节剂出现。它响应环境和内在刺激而发生的结构改变控制着 Hippo 信号通路的活性。然而，Hippo 信号传导的细胞骨架调节背后的确切机制尚不完全清楚。已知 RAP2 GTPase 可介导 Hippo 信号传导的机械反应，通过 MAP4K 和 MST1/2 激活核心 Hippo 激酶 LATS1/2。在这里，我们展示了 RAP2 GTPase 和细胞骨架之间的相互调节在 Hippo 信号传导中的关键作用。 RAP2 缺失破坏了 Hippo 通路对与 RhoA GTPase 抑制和肌动蛋白细胞骨架重塑相关的外部线索的反应，例如能量应激和血清剥夺。值得注意的是，RhoA 抑制剂和肌动蛋白干扰剂无法在 RAP2 缺陷细胞中有效激活 LATS1/2。 RNA 测序强调了 RAP2 基因缺失对肌动蛋白和微管网络的差异调节。一致的是，紫杉醇（一种微管稳定剂）在激活 LATS1/2 和抑制 RAP2 和 MAP4K4/6/7 敲除细胞中的细胞生长方面效果较差。总之，我们的研究结果将 RAP2 定位为 Hippo 信号传导的细胞骨架信号的中心整合器，这为了解 Hippo 调节和 Hippo 受损癌症的治疗干预提供了新途径。