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Yokoyama T, Kuga T, Itoh Y, Otake S, Omata C, Saitoh M, Miyazawa K. Smad2Δexon3 and Smad3 have distinct properties in signal transmission leading to TGF-β-induced cell motility. J Biol Chem 2022; 299:102820. [PMID: 36549646 PMCID: PMC9852702 DOI: 10.1016/j.jbc.2022.102820] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 12/11/2022] [Indexed: 12/24/2022] Open
Abstract
In mammalian cells, Smad2 and Smad3, two receptor-regulated Smad proteins, play crucial roles in the signal transmission of transforming growth factor-β (TGF-β) and are involved in various cell regulatory processes, including epithelial-mesenchymal transition-associated cell responses, that is, cell morphological changes, E-cadherin downregulation, stress fiber formation, and cell motility enhancement. Smad2 contains an additional exon encoding 30 amino acid residues compared with Smad3, leading to distinct Smad2 and Smad3 functional properties. Intriguingly, Smad2 also has an alternatively spliced isoform termed Smad2Δexon3 (also known as Smad2β) lacking the additional exon and behaving similarly to Smad3. However, Smad2Δexon3 and Smad3 signaling properties have not yet been compared in detail. In this study, we reveal that Smad2Δexon3 rescues multiple TGF-β-induced in vitro cellular responses that would become defective upon SMAD3 KO but does not rescue cell motility enhancement. Using Smad2Δexon3/Smad3 chimeric proteins, we identified that residues Arg-104 and Asn-210 in Smad3, which are not conserved in Smad2Δexon3, are key for TGF-β-enhanced cell motility. Moreover, we discovered that Smad2Δexon3 fails to rescue the enhanced cell motility as it does not mediate TGF-β signals to downregulate transcription of ARHGAP24, a GTPase-activating protein that targets Rac1. This study reports for the first time distinct signaling properties of Smad2Δexon3 and Smad3.
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Affiliation(s)
- Takashi Yokoyama
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Takahito Kuga
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan,Research Training Program for Undergraduates, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Yuka Itoh
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Shigeo Otake
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Chiho Omata
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Masao Saitoh
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan,Center for Medical Education and Science, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Keiji Miyazawa
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan.
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Itoh Y, Sawaguchi T, Fu H, Omata C, Saitoh M, Miyazawa K. Indole-derived compound SIS3 targets a subset of activated Smad complexes. J Biochem 2022; 173:283-291. [PMID: 36539324 DOI: 10.1093/jb/mvac104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/30/2022] [Accepted: 12/06/2022] [Indexed: 01/13/2023] Open
Abstract
Abstract
Smad2 and Smad3 are receptor-regulated Smad proteins that transmit signals from cytokines belonging to the transforming growth factor (TGF)-β family, which are vital for adult tissue homeostasis. The overactivation of such proteins often engenders the development of pathological conditions. Smad3 reportedly mediates TGF-β–induced fibrosis. Although various potential Smad3-specific inhibitors are being developed, their specificity and action mechanisms remain largely unknown. This study aimed to establish a biochemical platform to monitor Smad2- or Smad3-dependent TGF-β signaling using SMAD2, SMAD3 and SMAD2/3 knockout cell lines alongside TGF-β–dependent luciferase reporters and Smad mutant proteins. Using this platform, SIS3, an indole-derived compound widely used as a specific Smad3 inhibitor, was observed to preferentially suppress a subset of activated Smad complexes. However, its inhibition did not favor Smad3 signaling over Smad2 signaling. These findings indicate that SIS3 can be employed as a probe to examine the heterogeneous nature of Smad signaling that induces gene expression. However, its use as a Smad3-specific inhibitor should be avoided.
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Affiliation(s)
- Yuka Itoh
- Department of Biochemistry, University of Yamanashi, Shimokato 1110, Chuo, Yamanashi 409-3898, Japan
| | - Tomoe Sawaguchi
- Department of Biochemistry, University of Yamanashi, Shimokato 1110, Chuo, Yamanashi 409-3898, Japan
- Research Training Program for Undergraduates, University of Yamanashi, Shimokato 1110, Chuo, Yamanashi 409-3898, Japan
| | - Hao Fu
- Department of Biochemistry, University of Yamanashi, Shimokato 1110, Chuo, Yamanashi 409-3898, Japan
| | - Chiho Omata
- Department of Biochemistry, University of Yamanashi, Shimokato 1110, Chuo, Yamanashi 409-3898, Japan
| | - Masao Saitoh
- Department of Biochemistry, University of Yamanashi, Shimokato 1110, Chuo, Yamanashi 409-3898, Japan
- Center for Medical Education and Science, Graduate School of Medicine, University of Yamanashi, Shmokato 1110, Chuo, Yamanashi 409-3898, Japan
| | - Keiji Miyazawa
- Department of Biochemistry, University of Yamanashi, Shimokato 1110, Chuo, Yamanashi 409-3898, Japan
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Motizuki M, Koinuma D, Yokoyama T, Itoh Y, Omata C, Miyazono K, Saitoh M, Miyazawa K. TGF-β-induced cell motility requires downregulation of ARHGAPs to sustain Rac1 activity. J Biol Chem 2021; 296:100545. [PMID: 33741342 PMCID: PMC8079281 DOI: 10.1016/j.jbc.2021.100545] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 03/04/2021] [Accepted: 03/15/2021] [Indexed: 01/06/2023] Open
Abstract
Transforming growth factor-β (TGF-β) signaling promotes cancer progression. In particular, the epithelial-mesenchymal transition (EMT) induced by TGF-β is considered crucial to the malignant phenotype of cancer cells. Here, we report that the EMT-associated cellular responses induced by TGF-β are mediated by distinct signaling pathways that diverge at Smad3. By expressing chimeric Smad1/Smad3 proteins in SMAD3 knockout A549 cells, we found that the β4 region in the Smad3 MH1 domain is essential for TGF-β-induced cell motility, but is not essential for other EMT-associated responses including epithelial marker downregulation. TGF-β was previously reported to enhance cell motility by activating Rac1 via phosphoinositide 3-kinase. Intriguingly, TGF-β-dependent signaling mediated by Smad3's β4 region causes the downregulation of multiple mRNAs that encode GTPase activating proteins that target Rac1 (ARHGAPs), thereby attenuating Rac1 inactivation. Therefore, two independent pathways downstream of TGF-β type I receptor contribute cooperatively to sustained Rac1 activation, thereby leading to enhanced cell motility.
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Affiliation(s)
- Mitsuyoshi Motizuki
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Daizo Koinuma
- Department of Molecular Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Takashi Yokoyama
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Yuka Itoh
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Chiho Omata
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Kohei Miyazono
- Department of Molecular Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Masao Saitoh
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan; Center for Medical Education and Science, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Keiji Miyazawa
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi, Japan.
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Otake S, Itoh Y, Omata C, Saitoh M, Miyazawa K. ZEB1 and oncogenic Ras constitute a regulatory switch for stimulus-dependent E-cadherin downregulation. Cancer Sci 2020; 112:205-216. [PMID: 33068045 PMCID: PMC7780036 DOI: 10.1111/cas.14701] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 10/05/2020] [Accepted: 10/12/2020] [Indexed: 12/12/2022] Open
Abstract
E-cadherin, an epithelial cell-specific cell adhesion molecule, has both promoting and suppressing effects on tumor invasion and metastasis. It is often downregulated during cancer progression through gene deletion/mutation, transcriptional repression, or epigenetic silencing. We describe a novel regulatory switch to induce stimulus-dependent downregulation of mRNA encoding E-cadherin (CDH1 mRNA) in KRAS-mutated cancer cells. The regulatory switch consists of ZEB1 and oncogenic K-Ras, does not target the promoter region of CDH1, and requires an external cue to temporally downregulate E-cadherin expression. Its repressive effect is maintained as long as the external stimulus continues and is attenuated with cessation of the stimulus. Contextual external cues that turn this regulatory switch on include activation of protein kinase C or fibroblast growth factor signaling. The mode of action is distinct from that of EPCAM repression by ZEB1, which does not require an external cue. Thus, KRAS-mutated cancer cells acquire a novel mode of regulating E-cadherin expression depending on ZEB1, which could contribute to phenotypic plasticity of cancer cells during malignant progression.
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Affiliation(s)
- Shigeo Otake
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Chuo, Japan
| | - Yuka Itoh
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Chuo, Japan
| | - Chiho Omata
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Chuo, Japan
| | - Masao Saitoh
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Chuo, Japan.,Center for Medical Education and Science, Graduate School of Medicine, University of Yamanashi, Chuo, Japan
| | - Keiji Miyazawa
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Chuo, Japan
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Itoh Y, Koinuma D, Omata C, Ogami T, Motizuki M, Yaguchi SI, Itoh T, Miyake K, Tsutsumi S, Aburatani H, Saitoh M, Miyazono K, Miyazawa K. A comparative analysis of Smad-responsive motifs identifies multiple regulatory inputs for TGF-β transcriptional activation. J Biol Chem 2019; 294:15466-15479. [PMID: 31481467 DOI: 10.1074/jbc.ra119.009877] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 08/29/2019] [Indexed: 12/17/2022] Open
Abstract
Smad proteins are transcriptional regulators activated by TGF-β. They are known to bind to two distinct Smad-responsive motifs, namely the Smad-binding element (SBE) (5'-GTCTAGAC-3') and CAGA motifs (5'-AGCCAGACA-3' or 5'-TGTCTGGCT-3'). However, the mechanisms by which these motifs promote Smad activity are not fully elucidated. In this study, we performed DNA CASTing, binding assays, ChIP sequencing, and quantitative RT-PCR to dissect the details of Smad binding and function of the SBE and CAGA motifs. We observed a preference for Smad3 to bind CAGA motifs and Smad4 to bind SBE, and that either one SBE or a triple-CAGA motif forms a cis-acting functional half-unit for Smad-dependent transcription activation; combining two half-units allows efficient activation. Unexpectedly, the extent of Smad binding did not directly correlate with the abilities of Smad-binding sequences to induce gene expression. We found that Smad proteins are more tolerant of single bp mutations in the context of the CAGA motifs, with any mutation in the SBE disrupting function. CAGA and CAGA-like motifs but not SBE are widely distributed among stimulus-dependent Smad2/3-binding sites in normal murine mammary gland epithelial cells, and the number of CAGA and CAGA-like motifs correlates with fold-induction of target gene expression by TGF-β. These data, demonstrating Smad responsiveness can be tuned by both sequence and number of repeats, provide a compelling explanation for why CAGA motifs are predominantly used for Smad-dependent transcription activation in vivo.
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Affiliation(s)
- Yuka Itoh
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Daizo Koinuma
- Department of Molecular Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Chiho Omata
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Tomohiro Ogami
- Department of Molecular Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Mitsuyoshi Motizuki
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| | - So-Ichi Yaguchi
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Takuma Itoh
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan.,Research Training Program for Undergraduates, Graduate School of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Kunio Miyake
- Department of Social Medicine, Graduate School of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Shuichi Tsutsumi
- Genome Science Division, Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo 153-8904, Japan
| | - Hiroyuki Aburatani
- Genome Science Division, Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Tokyo 153-8904, Japan
| | - Masao Saitoh
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan.,Center for Medical Education and Science, Graduate School of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
| | - Kohei Miyazono
- Department of Molecular Pathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Keiji Miyazawa
- Department of Biochemistry, Graduate School of Medicine, University of Yamanashi, Yamanashi 409-3898, Japan
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