Arl15 upregulates the TGFβ family signaling by promoting the assembly of the Smad-complex
- A*STAR, Singapore, Singapore
- Nanyang Technological University, Singapore
Abstract
The hallmark event of the canonical transforming growth factor β (TGFβ) family signaling is the assembly of the Smad-complex, consisting of the common Smad, Smad4, and phosphorylated receptor-regulated Smads. How the Smad-complex is assembled and regulated is still unclear. Here, we report that active Arl15, an Arf-like small G protein, specifically binds to the MH2 domain of Smad4 and colocalizes with Smad4 at the endolysosome. The binding relieves the autoinhibition of Smad4, which is imposed by the intramolecular interaction between its MH1 and MH2 domains. Activated Smad4 subsequently interacts with phosphorylated receptor-regulated Smads, forming the Smad-complex. Our observations suggest that Smad4 functions as an effector and a GTPase activating protein (GAP) of Arl15. Assembly of the Smad-complex enhances the GAP activity of Smad4 toward Arl15, therefore dissociating Arl15 before the nuclear translocation of the Smad-complex. Our data further demonstrate that Arl15 positively regulates the TGFβ family signaling.
Data availability
All data generated or analyzed during this study are included in the manuscript and supporting file. Source Data files have been provided.
Article and author information
Author details
Funding
Ministry of Education - Singapore (AcRF Tier1 RG35/17)
- Meng Shi
- Hieng Chiong Tie
- Mahajan Divyanshu
- Xiuping Sun
- Yan Zhou
- Boon Kim Boh
- Lei Lu
Ministry of Education - Singapore (Tier2 MOE2015-T2-2-073)
- Meng Shi
- Hieng Chiong Tie
- Mahajan Divyanshu
- Xiuping Sun
- Yan Zhou
- Boon Kim Boh
- Lei Lu
Ministry of Education - Singapore (MOE2018-T2-2-026)
- Meng Shi
- Hieng Chiong Tie
- Mahajan Divyanshu
- Xiuping Sun
- Yan Zhou
- Boon Kim Boh
- Lei Lu
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2022, Shi et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Arl15 upregulates the TGFβ family signaling by promoting the assembly of the Smad-complex
eLife 11:e76146.
https://doi.org/10.7554/eLife.76146
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