Interplay of RAP2 GTPase and the cytoskeleton in Hippo pathway regulation

Chenzhou Wu; Xiaomin Cai; Ying Wang; Carlos D Rodriguez; Giorgia Zoaldi; Lydia Herrmann; Chun-Yuh Huang; Xiaoqiong Wang; Viraj R Sanghvi; Rongze O Lu; Zhipeng Meng

doi:10.1016/j.jbc.2024.107257

Interplay of RAP2 GTPase and the cytoskeleton in Hippo pathway regulation

J Biol Chem. 2024 Apr 2;300(5):107257. doi: 10.1016/j.jbc.2024.107257. Online ahead of print.

Authors

Affiliations

¹ Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA; Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida, USA.
² Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA.
³ Department of Biomedical Engineering, University of Miami, Coral Gables, Florida, USA.
⁴ Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida, USA; Department of Pathology and Laboratory Medicine, University of Miami Miller School of Medicine, Miami, Florida, USA.
⁵ Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida, USA; Department of Medicine, Herbert Irving Comprehensive Cancer Center, Columbia University Medical Center, New York City, New York, USA.
⁶ Department of Neurological Surgery, Brain Tumor Center, Helen Diller Cancer Center, UCSF, San Francisco, California, USA.
⁷ Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA; Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida, USA. Electronic address: zxm282@miami.edu.

Abstract

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 via 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.

Keywords: Hippo signaling; MAP4K; RAP2 GTPase; cytoskeleton; energy stress; mechanotransduction.

Grants and funding

R35 GM142504/GM/NIGMS NIH HHS/United States