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Niu J, Hu J, Wang Z. Scutellaria barbata D.Don extract regulates Ezrin-mediated triple negative breast cancer progress via suppressing the RhoA /ROCK1 signaling. Toxicol Res (Camb) 2024; 13:tfae033. [PMID: 38525246 PMCID: PMC10958765 DOI: 10.1093/toxres/tfae033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/21/2024] [Accepted: 02/02/2024] [Indexed: 03/26/2024] Open
Abstract
Background Triple-negative breast cancer (TNBC) lacks effective therapeutic targets. Scutellaria barbata D.Don (SB) has been revealed to have anti-breast cancer (BC) effect, but the effect of SB extract in TNBC is still unclear. Herein, this research delves into the underlying mechanism. Methods SB was extracted by solvent extraction, and the main components were identified using an Agilent 6,520 HPLC-Chip/Q-TOF (Chip/Q-TOF) MS system. In vitro cell experiments were conducted. The effects of SB extract alone, SB extract plus EGF, GSK alone, GSK plus Ezrin overexpression, or SB extract plus Ezrin overexpression on cell viability, invasion, migration, and apoptosis were examined by cell function experiments. The apoptosis- and RhoA/ROCK1 pathway-related protein levels were analyzed by western blot assay. Results Mass spectrometry analysis exhibited that SB extract mainly contains long-chain fatty acids and ursolic acid. SB extract mitigated TNBC cell biological phenotypes, apoptosis- and RhoA/ROCK1 pathway-related marker expressions, which were reversed by EGF. The further results found that GSK obviously weakens TNBC cell biological behaviors, apoptosis- and RhoA/ROCK1 signaling-related protein levels, while oe-Ezrin treatment reverses the effect of GSK on TNBC cells. Moreover, SB extract regulated Ezrin-mediated function of TNBC cells by impeding the RhoA/ROCK1 pathway. Conclusion Our findings demonstrated that SB extract regulated Ezrin-mediated proliferation, migration, invasion, and apoptosis of TNBC cells via suppressing the RhoA /ROCK1 signaling. Our results offer the experimental foundation for further investigation of the anti-cancer role of SB in TNBC cells. Highlights SB extract inhibits the biological phenotypes of TNBC cells.SB extract inhibits the biological behaviors of TNBC cells through the RhoA/ROCK1 pathway.SB extract modulates Ezrin-mediated TNBC cell proliferation, migration, invasion, and apoptosis via restraining the RhoA/ROCK1 signaling.
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Affiliation(s)
- Junjie Niu
- Department of Medical Oncology, Affiliated Hospital of Hunan Academy of Traditional Chinese Medicine, No. 58, Lushan Road, Yuelu District, Changsha, Hunan Province 410000, P. R. China
| | - Jinyang Hu
- Department of Medical Oncology, Affiliated Hospital of Hunan Academy of Traditional Chinese Medicine, No. 58, Lushan Road, Yuelu District, Changsha, Hunan Province 410000, P. R. China
| | - Zhu Wang
- Department of Medical Oncology, Affiliated Hospital of Hunan Academy of Traditional Chinese Medicine, No. 58, Lushan Road, Yuelu District, Changsha, Hunan Province 410000, P. R. China
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Buenaventura RGM, Merlino G, Yu Y. Ez-Metastasizing: The Crucial Roles of Ezrin in Metastasis. Cells 2023; 12:1620. [PMID: 37371090 DOI: 10.3390/cells12121620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/08/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023] Open
Abstract
Ezrin is the cytoskeletal organizer and functions in the modulation of membrane-cytoskeleton interaction, maintenance of cell shape and structure, and regulation of cell-cell adhesion and movement, as well as cell survival. Ezrin plays a critical role in regulating tumor metastasis through interaction with other binding proteins. Notably, Ezrin has been reported to interact with immune cells, allowing tumor cells to escape immune attack in metastasis. Here, we review the main functions of Ezrin, the mechanisms through which it acts, its role in tumor metastasis, and its potential as a therapeutic target.
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Affiliation(s)
- Rand Gabriel M Buenaventura
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Glenn Merlino
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yanlin Yu
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Multimodal cotranslational interactions direct assembly of the human multi-tRNA synthetase complex. Proc Natl Acad Sci U S A 2022; 119:e2205669119. [PMID: 36037331 PMCID: PMC9457175 DOI: 10.1073/pnas.2205669119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Amino acid ligation to cognate transfer RNAs (tRNAs) is catalyzed by aminoacyl-tRNA synthetases (aaRSs)-essential interpreters of the genetic code during translation. Mammalian cells harbor 20 cytoplasmic aaRSs, out of which 9 (in 8 proteins), with 3 non-aaRS proteins, AIMPs 1 to 3, form the ∼1.25-MDa multi-tRNA synthetase complex (MSC). The function of MSC remains uncertain, as does its mechanism of assembly. Constituents of multiprotein complexes encounter obstacles during assembly, including inappropriate interactions, topological constraints, premature degradation of unassembled subunits, and suboptimal stoichiometry. To facilitate orderly and efficient complex formation, some complexes are assembled cotranslationally by a mechanism in which a fully formed, mature protein binds a nascent partner as it emerges from the translating ribosome. Here, we show out of the 121 possible interaction events between the 11 MSC constituents, 15 are cotranslational. AIMPs are involved in the majority of these cotranslational interactions, suggesting they are not only critical for MSC structure but also for assembly. Unexpectedly, several cotranslational events involve more than the usual dyad of interacting proteins. We show two modes of cotranslational interaction, namely a "multisite" mechanism in which two or more mature proteins bind the same nascent peptide at distinct sites and a second "piggy-back" mechanism in which a mature protein carries a second fully formed protein and binds to a single site on an emerging peptide. Multimodal mechanisms of cotranslational interaction offer a diversity of pathways for ordered, piecewise assembly of small subcomplexes into larger heteromultimeric complexes such as the mammalian MSC.
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Hadjimichael AC, Foukas AF, Papadimitriou E, Kaspiris A, Peristiani C, Chaniotakis I, Kotsari M, Pergaris A, Theocharis S, Sarantis P, Christopoulou M, Psyrri A, Mavrogenis AF, Savvidou OD, Papagelopoulos PJ, Armakolas A. Doxycycline inhibits the progression of metastases in early-stage osteosarcoma by downregulating the expression of MMPs, VEGF and ezrin at primary sites. Cancer Treat Res Commun 2022; 32:100617. [PMID: 36027697 DOI: 10.1016/j.ctarc.2022.100617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 07/29/2022] [Accepted: 08/01/2022] [Indexed: 06/15/2023]
Abstract
INTRODUCTION Osteosarcoma (OS) is the most common primary osseous malignant tumour, with high propensity to metastasise in lungs. Pulmonary micro-metastases are present in up to 80% of patients at initial diagnosis and they are associated with significantly worse prognosis. Doxycycline (Dox) is a synthetic tetracycline that has been shown to have anti-cancer properties in vitro and in vivo, and inhibit angiogenesis - effects that may prove beneficial for several types of cancer. The aim of the present work was to study how Dox affects OS cell growth in vitro and in vivo and OS-driven pulmonary metastasis in vivo. METHODS In vitro, the effect of Dox was measured in MG-63 and 143B human OS cell viability, apoptosis, invasion and migration. In vivo, highly metastatic 143B cells were orthotopically implanted into the tibia of SCID mice. The tumour growth and pulmonary metastases between Dox treated and untreated, non-amputated and early amputated xenografts were examined. RESULTS In vitro, Dox decreased viability, inhibited invasion, migration, and induced the apoptosis of OS cells. In vivo, Dox significantly enhanced tumour necrosis at primary OS sites, similarly to its in vitro effect, and downregulated the expression of Ki67, MMP2, MMP9, VEGFA and ezrin. It also decreased circulating VEGFA and MMP9 protein levels, in line with the decreased metastatic burden in Dox-treated mice (non-amputated and early-amputated). CONCLUSIONS Reprofiling of Dox can prevent the evolvement of pulmonary micro-metastases to clinically detectable macro-metastases and suppress the lethal progress of OS by inhibiting the expression of MMPs, VEGFA and ezrin at primary sites.
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Affiliation(s)
- Argyris C Hadjimichael
- Department of Orthopaedics, St Mary's Hospital, Imperial College Healthcare NHS Trust, Praed Street, W2 1NY, London, UK.
| | - Athanasios F Foukas
- Third Department of Orthopaedic surgery, "KAT" General Hospital of Athens, 2, Nikis Street, 14561, Kifissia, Greece.
| | - Evangelia Papadimitriou
- Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, 26504, Patras, Greece.
| | - Angelos Kaspiris
- Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, 26504, Patras, Greece.
| | - Chrysostomi Peristiani
- Medical School, National and Kapodistrian University of Athens,75, Mikras Asias Street, Goudi, 11527, Athens, Greece.
| | - Ioannis Chaniotakis
- Healthcare Directorate of the Hellenic Air Force General Staff, Athens, 3, P. Kanellopoulou Street, 11525, Athens, Greece.
| | - Maria Kotsari
- Physiology Laboratory, Athens Medical School, National and Kapodistrian University of Athens, 75, Mikras Asias Street, Physiology Lab, Bld 16, Goudi, 11527, Athens, Greece..
| | - Alexandros Pergaris
- First Department of Pathology, Medical School, National and Kapodistrian University of Athens, 75, Mikras Asias Street, Bld 10, Goudi, 11527 Athens, Greece.
| | - Stamatios Theocharis
- First Department of Pathology, Medical School, National and Kapodistrian University of Athens, 75, Mikras Asias Street, Bld 10, Goudi, 11527 Athens, Greece.
| | - Panagiotis Sarantis
- First Department of Pathology, Medical School, National and Kapodistrian University of Athens, 75, Mikras Asias Street, Bld 10, Goudi, 11527 Athens, Greece.
| | - Magdalini Christopoulou
- Laboratory of Molecular Pharmacology, Department of Pharmacy, University of Patras, 26504, Patras, Greece.
| | - Amanda Psyrri
- Section of Medical Oncology, Department of Internal Medicine, Faculty of Medicine, National and Kapodistrian University of Athens, Attikon University Hospital,1 Rimini Street, Chaidari, 12462, Athens, Greece.
| | - Andreas F Mavrogenis
- First Department of Orthopaedic Surgery, National and Kapodistrian University of Athens, Faculty of Medicine, Attikon University hospital, Athens,1 Rimini Street, Chaidari,12462, Athens, Greece..
| | - Olga D Savvidou
- First Department of Orthopaedic Surgery, National and Kapodistrian University of Athens, Faculty of Medicine, Attikon University hospital, Athens,1 Rimini Street, Chaidari,12462, Athens, Greece..
| | - Panayiotis J Papagelopoulos
- First Department of Orthopaedic Surgery, National and Kapodistrian University of Athens, Faculty of Medicine, Attikon University hospital, Athens,1 Rimini Street, Chaidari,12462, Athens, Greece..
| | - Athanasios Armakolas
- Physiology Laboratory, Athens Medical School, National and Kapodistrian University of Athens, 75, Mikras Asias Street, Physiology Lab, Bld 16, Goudi, 11527, Athens, Greece..
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Barik GK, Sahay O, Paul D, Santra MK. Ezrin gone rogue in cancer progression and metastasis: An enticing therapeutic target. Biochim Biophys Acta Rev Cancer 2022; 1877:188753. [PMID: 35752404 DOI: 10.1016/j.bbcan.2022.188753] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 06/16/2022] [Accepted: 06/18/2022] [Indexed: 12/12/2022]
Abstract
Cancer metastasis is the primary cause of morbidity and mortality in cancer as it remains the most complicated, devastating, and enigmatic aspect of cancer. Several decades of extensive research have identified several key players closely associated with metastasis. Among these players, cytoskeletal linker Ezrin (the founding member of the ERM (Ezrin-Radixin-Moesin) family) was identified as a critical promoter of metastasis in pediatric cancers in the early 21st century. Ezrin was discovered 40 years ago as a aminor component of intestinal epithelial microvillus core protein, which is enriched in actin-containing cell surface structures. It controls gastric acid secretion and plays diverse physiological roles including maintaining cell polarity, regulating cell adhesion, cell motility and morphogenesis. Extensive research for more than two decades evinces that Ezrin is frequently dysregulated in several human cancers. Overexpression, altered subcellular localization and/or aberrant activation of Ezrin are closely associated with higher metastatic incidence and patient mortality, thereby justifying Ezrin as a valuable prognostic biomarker in cancer. Ezrin plays multifaceted role in multiple aspects of cancer, with its significant contribution in the complex metastatic cascade, through reorganizing the cytoskeleton and deregulating various cellular signaling pathways. Current preclinical studies using genetic and/or pharmacological approaches reveal that inactivation of Ezrin results in significant inhibition of Ezrin-mediated tumor growth and metastasis as well as increase in the sensitivity of cancer cells to various chemotherapeutic drugs. In this review, we discuss the recent advances illuminating the molecular mechanisms responsible for Ezrin dysregulation in cancer and its pleiotropic role in cancer progression and metastasis. We also highlight its potential as a prognostic biomarker and therapeutic target in various cancers. More importantly, we put forward some potential questions, which we strongly believe, will stimulate both basic and translational research to better understand Ezrin-mediated malignancy, ultimately leading to the development of Ezrin-targeted cancer therapy for the betterment of human life.
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Affiliation(s)
- Ganesh Kumar Barik
- Cancer Biology Division, National Centre for Cell Science, Ganeshkhind Road, Pune, Maharashtra 411007, India; Department of Biotechnology, Savitribai Phule Pune University, Ganeshkhind Road, Pune, Maharashtra 411007, India
| | - Osheen Sahay
- Cancer Biology Division, National Centre for Cell Science, Ganeshkhind Road, Pune, Maharashtra 411007, India; Department of Biotechnology, Savitribai Phule Pune University, Ganeshkhind Road, Pune, Maharashtra 411007, India
| | - Debasish Paul
- Laboratory of Cancer Biology and Genetics, Centre for Cancer Research, National Cancer Institute, Bethesda, MD, USA
| | - Manas Kumar Santra
- Cancer Biology Division, National Centre for Cell Science, Ganeshkhind Road, Pune, Maharashtra 411007, India.
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Yang M, Ma YX, Zhi Y, Wang HB, Zhao L, Wang PS, Niu JT. Inhibitors of IFN gene stimulators (STING) improve intestinal ischemia-reperfusion-induced acute lung injury by activating AMPK signaling. Eur J Med Res 2022; 27:79. [PMID: 35642042 PMCID: PMC9153160 DOI: 10.1186/s40001-022-00703-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 05/10/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Acute lung injury (ALI) caused by intestinal ischemia-reperfusion is a life-threatening disease. Interferon gene stimulator (STING) is a cytoplasmic DNA sensor that participates in the initiation of the inflammatory response. This study aims to establish whether C-176 (STING inhibitor) improves ALI under intestinal ischemia-reperfusion conditions. METHODS To induce ALI, 72 male C57BL/6 mice were subjected to intestinal ischemia for 60 min and reperfusion for 3 h. Through intraperitoneal injection, C-176, a selective STING inhibitor, was injected 30 min before surgical treatment; meanwhile, compound C, an antagonist of adenosine monophosphate-activated protein kinase (AMPK), was administered 30 min after surgery. Based on immunofluorescence and Western blot assays, post-ALI assessments included lung water content (TLW), bronchoalveolar lavage fluid (BALF) protein, H&E staining, Masson staining, pulmonary pyroptosis [Gasdermin-D (GSDMD), cleaved caspase-1], and apoptosis (TUNEL, cleaved caspase-3). RESULTS C-176 administration significantly attenuated intestinal ischemia-reperfusion-mediated ALI; this effect was reflected by exacerbated TLW and BALF protein, aggravated lung injury score, elevated degree of pulmonary fibrosis, increased TUNEL- and GSDMD-positive cells, and upregulated phospho-AMPK, cleaved caspase-1, cleaved caspase-3 and IFNβ mRNA expression. Moreover, C-176 increased phospho-AMPK under ALI conditions. Nonetheless, compound C partially reversed these beneficial effects. CONCLUSION C-176, a selective STING inhibitor, improves intestinal ischemia-reperfusion-mediated ALI, and its underlying mechanism may be associated with AMPK signal activation.
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Affiliation(s)
- Mei Yang
- Department of Gerontology, Cangzhou Central Hospital, Hebei Medical University, No. 16, Xinhua West Road, Cangzhou, China.
| | - Yu-Xia Ma
- Department of Gerontology, Cangzhou Central Hospital, Hebei Medical University, No. 16, Xinhua West Road, Cangzhou, China
| | - Ying Zhi
- Department of Gerontology, Cangzhou Central Hospital, Hebei Medical University, No. 16, Xinhua West Road, Cangzhou, China
| | - Hai-Bin Wang
- Department of Gerontology, Cangzhou Central Hospital, Hebei Medical University, No. 16, Xinhua West Road, Cangzhou, China
| | - Li Zhao
- Department of Gerontology, Cangzhou Central Hospital, Hebei Medical University, No. 16, Xinhua West Road, Cangzhou, China
| | - Peng-Sheng Wang
- Department of Gerontology, Cangzhou Central Hospital, Hebei Medical University, No. 16, Xinhua West Road, Cangzhou, China
| | - Jie-Ting Niu
- Department of Gerontology, Cangzhou Central Hospital, Hebei Medical University, No. 16, Xinhua West Road, Cangzhou, China
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Zhou WH, Du WD, Li YF, Al-Aroomi MA, Yan C, Wang Y, Zhang ZY, Liu FY, Sun CF. The Overexpression of Fibronectin 1 Promotes Cancer Progression and Associated with M2 Macrophages Polarization in Head and Neck Squamous Cell Carcinoma Patients. Int J Gen Med 2022; 15:5027-5042. [PMID: 35607361 PMCID: PMC9123938 DOI: 10.2147/ijgm.s364708] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 05/10/2022] [Indexed: 12/24/2022] Open
Abstract
Purpose This study aimed to investigate the biological roles of fibronectin 1 (FN1) in head and neck squamous cell carcinoma (HNSCC) and its effects on macrophage M2 polarization. Methods We analyzed FN1 expression pattern and examined its clinical relevance in HNSCC progression by bioinformatic analysis. Small interfering RNA (siRNA) was utilized to silence FN1 in HNSCC cells. Cell counting kit-8 (CCK-8) assay, colony formation assay, Transwell assay and wound healing assay were performed to reveal the effect of FN1 on malignant behaviors of HNSCC cells. Moreover, a co-culture model of macrophages and HNSCC cells was established to investigate whether FN1 induce macrophage M2 polarization. Finally, we used bioinformatic methods to explore the possible FN1-related pathways in HNSCC. Results FN1 is significantly overexpressed in HNSCC patients and has been obviously correlated with higher pathological stage and poor prognosis. Downregulation of FN1 suppressed the proliferation, migration and invasion of HNSCC cells, and inhibited macrophage M2 polarization in vitro. In addition, “PI3K-Akt” and “MAPK” signaling pathways may be involved in the malignant process of FN1 in HNSCC. Conclusion The overexpression of FN1 promotes HNSCC progression and induces macrophages M2 polarization. FN1 may serve as a promising prognostic biomarker and therapeutic target in HNSCC.
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Affiliation(s)
- Wan-Hang Zhou
- Department of Oral Maxillofacial-Head and Neck Surgery, School of Stomatology, China Medical University; Oral Diseases Laboratory of Liaoning, Shenyang, 110000, People’s Republic of China
| | - Wei-Dong Du
- Department of Oral Maxillofacial-Head and Neck Surgery, School of Stomatology, China Medical University; Oral Diseases Laboratory of Liaoning, Shenyang, 110000, People’s Republic of China
| | - Yan-Fei Li
- Department of Prosthodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University; Guangdong Provincial Key Laboratory of Stomatology, Guangzhou, 510055, People’s Republic of China
| | - Maged Ali Al-Aroomi
- Department of Oral Maxillofacial-Head and Neck Surgery, School of Stomatology, China Medical University; Oral Diseases Laboratory of Liaoning, Shenyang, 110000, People’s Republic of China
| | - Cong Yan
- Department of Oral Maxillofacial-Head and Neck Surgery, School of Stomatology, China Medical University; Oral Diseases Laboratory of Liaoning, Shenyang, 110000, People’s Republic of China
| | - Yao Wang
- Department of Oral Maxillofacial-Head and Neck Surgery, School of Stomatology, China Medical University; Oral Diseases Laboratory of Liaoning, Shenyang, 110000, People’s Republic of China
| | - Ze-Ying Zhang
- Department of Oral Maxillofacial-Head and Neck Surgery, School of Stomatology, China Medical University; Oral Diseases Laboratory of Liaoning, Shenyang, 110000, People’s Republic of China
| | - Fa-Yu Liu
- Department of Oral Maxillofacial-Head and Neck Surgery, School of Stomatology, China Medical University; Oral Diseases Laboratory of Liaoning, Shenyang, 110000, People’s Republic of China
- Correspondence: Fa-Yu Liu; Chang-Fu Sun, Department of Oral Maxillofacial-Head and Neck Surgery, School of Stomatology, China Medical University; Oral Diseases Laboratory of Liaoning, 117 Nanjing North Road, Heping District, Shenyang, Liaoning, 110000, People’s Republic of China, Tel +86 24 22894773, Fax +86 24 86602310, Email ;
| | - Chang-Fu Sun
- Department of Oral Maxillofacial-Head and Neck Surgery, School of Stomatology, China Medical University; Oral Diseases Laboratory of Liaoning, Shenyang, 110000, People’s Republic of China
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Cotranslational interaction of human EBP50 and ezrin overcomes masked binding site during complex assembly. Proc Natl Acad Sci U S A 2022; 119:2115799119. [PMID: 35140182 PMCID: PMC8851480 DOI: 10.1073/pnas.2115799119] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/23/2021] [Indexed: 12/13/2022] Open
Abstract
Multiprotein assemblages are the intracellular workhorses of many physiological processes. Assembly of constituents into complexes can be driven by stochastic, domain-dependent, posttranslational events in which mature, folded proteins specifically interact. However, inaccessibility of interacting surfaces in mature proteins (e.g., due to "buried" domains) can obstruct complex formation. Mechanisms by which multiprotein complex constituents overcome topological impediments remain enigmatic. For example, the heterodimeric complex formed by EBP50 and ezrin must address this issue as the EBP50-interacting domain in ezrin is obstructed by a self-interaction that occupies the EBP50 binding site. Here, we show that the EBP50-ezrin complex is formed by a cotranslational mechanism in which the C terminus of mature, fully formed EBP50 binds the emerging, ribosome-bound N-terminal FERM domain of ezrin during EZR mRNA translation. Consistent with this observation, a C-terminal EBP50 peptide mimetic reduces the cotranslational interaction and abrogates EBP50-ezrin complex formation. Phosphorylation of EBP50 at Ser339 and Ser340 abrogates the cotranslational interaction and inhibits complex formation. In summary, we show that the function of eukaryotic mRNA translation extends beyond "simple" generation of a linear peptide chain that folds into a tertiary structure, potentially for subsequent complex assembly; importantly, translation can facilitate interactions with sterically inaccessible domains to form functional multiprotein complexes.
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