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Usher ET, Fossat MJ, Holehouse AS. Phosphorylation of disordered proteins tunes local and global intramolecular interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.10.598315. [PMID: 38915510 PMCID: PMC11195077 DOI: 10.1101/2024.06.10.598315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Protein post-translational modifications, such as phosphorylation, are important regulatory signals for diverse cellular functions. In particular, intrinsically disordered protein regions (IDRs) are subject to phosphorylation as a means to modulate their interactions and functions. Toward understanding the relationship between phosphorylation in IDRs and specific functional outcomes, we must consider how phosphorylation affects the IDR conformational ensemble. Various experimental techniques are suited to interrogate the features of IDR ensembles; molecular simulations can provide complementary insights and even illuminate ensemble features that may be experimentally inaccessible. Therefore, we sought to expand the tools available to study phosphorylated IDRs by all-atom Monte Carlo simulations. To this end, we implemented parameters for phosphoserine (pSer) and phosphothreonine (pThr) into the OPLS version of the continuum solvent model, ABSINTH, and assessed their performance in all-atom simulations compared to published findings. We simulated short (< 20 residues) and long (> 80 residues) phospho-IDRs that, collectively, survey both local and global phosphorylation-induced changes to the ensemble. Our simulations of four well-studied phospho-IDRs show near-quantitative agreement with published findings for these systems via metrics including changes to radius of gyration, transient helicity, and persistence length. We also leveraged the inherent advantage of sequence control in molecular simulations to explore the conformational effects of diverse combinations of phospho-sites in two multi-phosphorylated IDRs. Our results support and expand on prior observations that connect phosphorylation to changes in the IDR conformational ensemble. Herein, we describe phosphorylation as a means to alter sequence chemistry, net charge and charge patterning, and intramolecular interactions, which can collectively modulate the local and global IDR ensemble features.
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Affiliation(s)
- Emery T. Usher
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
- Center for Biomolecular Condensates (CBC), Washington University in St. Louis, St. Louis, MO, USA
| | - Martin J. Fossat
- Department of Biological Physics, Max Planck Institute of Immunobiology and Epigenetics, Freiburg im Breisgau, Germany
| | - Alex S. Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
- Center for Biomolecular Condensates (CBC), Washington University in St. Louis, St. Louis, MO, USA
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2
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Allen MC, Karplus PA, Mehl RA, Cooley RB. Genetic Encoding of Phosphorylated Amino Acids into Proteins. Chem Rev 2024; 124:6592-6642. [PMID: 38691379 DOI: 10.1021/acs.chemrev.4c00110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2024]
Abstract
Reversible phosphorylation is a fundamental mechanism for controlling protein function. Despite the critical roles phosphorylated proteins play in physiology and disease, our ability to study individual phospho-proteoforms has been hindered by a lack of versatile methods to efficiently generate homogeneous proteins with site-specific phosphoamino acids or with functional mimics that are resistant to phosphatases. Genetic code expansion (GCE) is emerging as a transformative approach to tackle this challenge, allowing direct incorporation of phosphoamino acids into proteins during translation in response to amber stop codons. This genetic programming of phospho-protein synthesis eliminates the reliance on kinase-based or chemical semisynthesis approaches, making it broadly applicable to diverse phospho-proteoforms. In this comprehensive review, we provide a brief introduction to GCE and trace the development of existing GCE technologies for installing phosphoserine, phosphothreonine, phosphotyrosine, and their mimics, discussing both their advantages as well as their limitations. While some of the technologies are still early in their development, others are already robust enough to greatly expand the range of biologically relevant questions that can be addressed. We highlight new discoveries enabled by these GCE approaches, provide practical considerations for the application of technologies by non-GCE experts, and also identify avenues ripe for further development.
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Affiliation(s)
- Michael C Allen
- Department of Biochemistry and Biophysics, Oregon State University, GCE4All Research Center, 2011 Agricultural and Life Sciences, Corvallis, Oregon 97331 United States
| | - P Andrew Karplus
- Department of Biochemistry and Biophysics, Oregon State University, GCE4All Research Center, 2011 Agricultural and Life Sciences, Corvallis, Oregon 97331 United States
| | - Ryan A Mehl
- Department of Biochemistry and Biophysics, Oregon State University, GCE4All Research Center, 2011 Agricultural and Life Sciences, Corvallis, Oregon 97331 United States
| | - Richard B Cooley
- Department of Biochemistry and Biophysics, Oregon State University, GCE4All Research Center, 2011 Agricultural and Life Sciences, Corvallis, Oregon 97331 United States
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Parsons M, Parsons B, Dean M, DeRocher AE, Islam Z, Maly DJ, Jensen BC. An essential Trypanosoma brucei protein kinase: a functional analysis of regulation and the identification of inhibitors. FRONTIERS IN PARASITOLOGY 2023; 2:1272378. [PMID: 38099268 PMCID: PMC10720658 DOI: 10.3389/fpara.2023.1272378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
Introduction The protein serine/threonine kinase AEK1 is essential in the pathogenic stage of Trypanosoma brucei, the causative agent of African trypanosomiasis. AEK1 is a member of the AGC protein kinase family, although it is not closely related to a specific human AGC kinase. Our previous chemical genetic studies showed that targeted inhibition of AEK1 in parasites expressing analog-sensitive AEK1 blocked parasite growth and enhanced survival of infected mice. Methods To further validate AEK1 as a drug target, we used the chemical genetic system to determine the effect of a 24 hour loss of AEK1 activity on cell viability at the clonal level. A panel of 429 protein kinase inhibitors were screened against the wild-type protein for binding, using time-resolved fluorescence energy transfer (TR-FRET). The role of phosphorylation sites and motifs was probed by determining whether expression of proteins harboring mutations in these sequences could rescue AEK1 conditional knockout parasites. To determine the effect that mutations in the phosphosites have on the kinase activity of cellular AEK1 we compared the in vitro kinase activity of mutant and wild-type proteins immunoprecipitated from parasite lysates using the exogenous substrate MBP. Finally, the tagged AEK1 protein was localized by deconvolution microscopy. Results After a 24 hour exposure to an AEK1 inhibitory analog in the chemical genetic system, less than five percent of the remaining live cells can clonally expand, further validating AEK1 as a drug target. In the AEK1 inhibitor screening assay, we identified 17 hit compounds. Complementation studies showed that of the two known phosphorylation sites in the activation loop; mutation of one abolished function while mutation of the other had no discernable effect. Mutation of the other two AEK1 phosphosites gave intermediate phenotypes. Mutations in either the hydrophobic motif at the C-terminus of the protein or in the region of AEK1 predicted to bind the hydrophobic motif were also required for function. All parasites with defective AEK1 showed reduced proliferation and defects in cytokinesis, although the tested mutations differed in terms of the extent of cell death. Kinase activity of immunoprecipitated AEK1 phosphosite mutants largely paralleled the effects seen in complementation studies, although the mutation of the phosphosite adjacent to the hydrophobic motif had a greater impact on activity than predicted by the complementation studies. AEK1 was localized to cytoplasmic puncta distinct from glycosomes and acidocalcisomes. Discussion The rapid loss of viability of cells inhibited for AEK1 supports the idea that a short course of treatment that target AEK1 may be sufficient for treatment of people or animals infected with T. brucei. Key regulatory elements between AEK1 and its closest mammalian homolog appear to be largely conserved despite the vast evolutionary distance between mammals and T. brucei. The presence of AEK1 in cytoplasmic puncta raises the possibility that its localization may also play a role in functional activity.
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Affiliation(s)
- Marilyn Parsons
- Seattle Children’s Research Institute, Seattle, WA, USA
- Department of Pediatrics, University of Washington, Seattle, WA, USA
- Department of Global Health, University of Washington, Seattle, WA
| | - Ben Parsons
- Seattle Children’s Research Institute, Seattle, WA, USA
| | - Marissa Dean
- Seattle Children’s Research Institute, Seattle, WA, USA
| | | | - Zeba Islam
- Department of Chemistry, University of Washington, Seattle, WA
| | - Dustin J. Maly
- Department of Chemistry, University of Washington, Seattle, WA
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Fruergaard MU, Nielsen CJF, Kjeldsen CR, Iversen L, Andersen JL, Nissen P. Activation and inhibition of the C-terminal kinase domain of p90 ribosomal S6 kinases. Life Sci Alliance 2023; 6:e202201425. [PMID: 36806093 PMCID: PMC9941302 DOI: 10.26508/lsa.202201425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 02/08/2023] [Accepted: 02/09/2023] [Indexed: 02/22/2023] Open
Abstract
The p90 ribosomal S6 kinases (RSKs) contain two distinct catalytic kinase domains, the N-terminal and C-terminal kinase domains (NTKD and CTKD, respectively). The activation of CTKD is regulated by phosphorylation by extracellular signal-regulated kinase (ERK1/2) and an autoinhibitory αL helix. Through a mutational series in vitro of the RSK CTKDs, we found a complex mechanism lifting autoinhibition that led us to design constitutively active RSK CTKDs. These are based on a phosphomimetic mutation and a C-terminal truncation (e.g., RSK2 T577E D694*) where a high activity in absence of ERK phosphorylation is obtained. Using these constructs, we characterize IC50 values of ATP-competitive inhibitors and provide a setup for determining specificity constants (kinact/Ki) of covalent CTKD inhibitors.
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Affiliation(s)
- Marlene Uglebjerg Fruergaard
- Department of Molecular Biology and Genetics, DANDRITE - Nordic EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus C, Denmark
| | - Christine Juul Fælled Nielsen
- Department of Molecular Biology and Genetics, DANDRITE - Nordic EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus C, Denmark
| | - Cecilia Rosada Kjeldsen
- Department of Clinical Medicine- The Department of Dermatology and Venereology, Aarhus N, Denmark
| | - Lars Iversen
- Department of Clinical Medicine- The Department of Dermatology and Venereology, Aarhus N, Denmark
| | | | - Poul Nissen
- Department of Molecular Biology and Genetics, DANDRITE - Nordic EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus C, Denmark
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Quévillon Huberdeau M, Shah VN, Nahar S, Neumeier J, Houle F, Bruckmann A, Gypas F, Nakanishi K, Großhans H, Meister G, Simard MJ. A specific type of Argonaute phosphorylation regulates binding to microRNAs during C. elegans development. Cell Rep 2022; 41:111822. [PMID: 36516777 PMCID: PMC10436268 DOI: 10.1016/j.celrep.2022.111822] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 09/22/2022] [Accepted: 11/21/2022] [Indexed: 12/15/2022] Open
Abstract
Argonaute proteins are at the core of the microRNA-mediated gene silencing pathway essential for animals. In C. elegans, the microRNA-specific Argonautes ALG-1 and ALG-2 regulate multiple processes required for proper animal developmental timing and viability. Here we identified a phosphorylation site on ALG-1 that modulates microRNA association. Mutating ALG-1 serine 642 into a phospho-mimicking residue impairs microRNA binding and causes embryonic lethality and post-embryonic phenotypes that are consistent with alteration of microRNA functions. Monitoring microRNA levels in alg-1 phosphorylation mutant animals shows that microRNA passenger strands increase in abundance but are not preferentially loaded into ALG-1, indicating that the miRNA binding defects could lead to microRNA duplex accumulation. Our genetic and biochemical experiments support protein kinase A (PKA) KIN-1 as the putative kinase that phosphorylates ALG-1 serine 642. Our data indicate that PKA triggers ALG-1 phosphorylation to regulate its microRNA association during C. elegans development.
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Affiliation(s)
- Miguel Quévillon Huberdeau
- CHU de Québec-Université Laval Research Center (Oncology Division), Québec City, QC G1R 3S3, Canada; Université Laval Cancer Research Centre, Québec City, QC G1R 3S3, Canada
| | - Vivek Nilesh Shah
- CHU de Québec-Université Laval Research Center (Oncology Division), Québec City, QC G1R 3S3, Canada; Université Laval Cancer Research Centre, Québec City, QC G1R 3S3, Canada
| | - Smita Nahar
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Julia Neumeier
- Regensburg Center for Biochemistry (RCB), Laboratory for RNA Biology, University of Regensburg, 93053 Regensburg, Germany
| | - François Houle
- CHU de Québec-Université Laval Research Center (Oncology Division), Québec City, QC G1R 3S3, Canada; Université Laval Cancer Research Centre, Québec City, QC G1R 3S3, Canada
| | - Astrid Bruckmann
- Regensburg Center for Biochemistry (RCB), Laboratory for RNA Biology, University of Regensburg, 93053 Regensburg, Germany
| | - Foivos Gypas
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland
| | - Kotaro Nakanishi
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA; Center for RNA Biology, Columbus, OH 43210, USA
| | - Helge Großhans
- Friedrich Miescher Institute for Biomedical Research, 4058 Basel, Switzerland; University of Basel, 4056 Basel, Switzerland
| | - Gunter Meister
- Regensburg Center for Biochemistry (RCB), Laboratory for RNA Biology, University of Regensburg, 93053 Regensburg, Germany
| | - Martin J Simard
- CHU de Québec-Université Laval Research Center (Oncology Division), Québec City, QC G1R 3S3, Canada; Université Laval Cancer Research Centre, Québec City, QC G1R 3S3, Canada.
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Vesely CH, Reardon PN, Yu Z, Barbar E, Mehl RA, Cooley RB. Accessing isotopically labeled proteins containing genetically encoded phosphoserine for NMR with optimized expression conditions. J Biol Chem 2022; 298:102613. [PMID: 36265582 PMCID: PMC9678770 DOI: 10.1016/j.jbc.2022.102613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 10/11/2022] [Accepted: 10/12/2022] [Indexed: 11/05/2022] Open
Abstract
Phosphoserine (pSer) sites are primarily located within disordered protein regions, making it difficult to experimentally ascertain their effects on protein structure and function. Therefore, the production of 15N- (and 13C)-labeled proteins with site-specifically encoded pSer for NMR studies is essential to uncover molecular mechanisms of protein regulation by phosphorylation. While genetic code expansion technologies for the translational installation of pSer in Escherichia coli are well established and offer a powerful strategy to produce site-specifically phosphorylated proteins, methodologies to adapt them to minimal or isotope-enriched media have not been described. This shortcoming exists because pSer genetic code expansion expression hosts require the genomic ΔserB mutation, which increases pSer bioavailability but also imposes serine auxotrophy, preventing growth in minimal media used for isotopic labeling of recombinant proteins. Here, by testing different media supplements, we restored normal BL21(DE3) ΔserB growth in labeling media but subsequently observed an increase of phosphatase activity and mis-incorporation not typically seen in standard rich media. After rounds of optimization and adaption of a high-density culture protocol, we were able to obtain ≥10 mg/L homogenously labeled, phosphorylated superfolder GFP. To demonstrate the utility of this method, we also produced the intrinsically disordered serine/arginine-rich region of the SARS-CoV-2 Nucleocapsid protein labeled with 15N and pSer at the key site S188 and observed the resulting peak shift due to phosphorylation by 2D and 3D heteronuclear single quantum correlation analyses. We propose this cost-effective methodology will pave the way for more routine access to pSer-enriched proteins for 2D and 3D NMR analyses.
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Affiliation(s)
- Cat Hoang Vesely
- GCE4All Research Center, Oregon State University, Corvallis, Oregon, USA,Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | - Patrick N. Reardon
- Oregon State University NMR Facility, Oregon State University, Corvallis, Oregon, USA
| | - Zhen Yu
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | - Elisar Barbar
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | - Ryan A. Mehl
- GCE4All Research Center, Oregon State University, Corvallis, Oregon, USA,Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | - Richard B. Cooley
- GCE4All Research Center, Oregon State University, Corvallis, Oregon, USA,Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA,For correspondence: Richard B. Cooley
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Kozeleková A, Náplavová A, Brom T, Gašparik N, Šimek J, Houser J, Hritz J. Phosphorylated and Phosphomimicking Variants May Differ—A Case Study of 14-3-3 Protein. Front Chem 2022; 10:835733. [PMID: 35321476 PMCID: PMC8935074 DOI: 10.3389/fchem.2022.835733] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 02/14/2022] [Indexed: 12/12/2022] Open
Abstract
Protein phosphorylation is a critical mechanism that biology uses to govern cellular processes. To study the impact of phosphorylation on protein properties, a fully and specifically phosphorylated sample is required although not always achievable. Commonly, this issue is overcome by installing phosphomimicking mutations at the desired site of phosphorylation. 14-3-3 proteins are regulatory protein hubs that interact with hundreds of phosphorylated proteins and modulate their structure and activity. 14-3-3 protein function relies on its dimeric nature, which is controlled by Ser58 phosphorylation. However, incomplete Ser58 phosphorylation has obstructed the detailed study of its effect so far. In the present study, we describe the full and specific phosphorylation of 14-3-3ζ protein at Ser58 and we compare its characteristics with phosphomimicking mutants that have been used in the past (S58E/D). Our results show that in case of the 14-3-3 proteins, phosphomimicking mutations are not a sufficient replacement for phosphorylation. At physiological concentrations of 14-3-3ζ protein, the dimer-monomer equilibrium of phosphorylated protein is much more shifted towards monomers than that of the phosphomimicking mutants. The oligomeric state also influences protein properties such as thermodynamic stability and hydrophobicity. Moreover, phosphorylation changes the localization of 14-3-3ζ in HeLa and U251 human cancer cells. In summary, our study highlights that phosphomimicking mutations may not faithfully represent the effects of phosphorylation on the protein structure and function and that their use should be justified by comparing to the genuinely phosphorylated counterpart.
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Affiliation(s)
- Aneta Kozeleková
- Central European Institute of Technology, Masaryk University, Brno, Czechia
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czechia
| | | | - Tomáš Brom
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czechia
| | - Norbert Gašparik
- Central European Institute of Technology, Masaryk University, Brno, Czechia
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czechia
| | - Jan Šimek
- Central European Institute of Technology, Masaryk University, Brno, Czechia
| | - Josef Houser
- Central European Institute of Technology, Masaryk University, Brno, Czechia
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czechia
| | - Jozef Hritz
- Central European Institute of Technology, Masaryk University, Brno, Czechia
- Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czechia
- *Correspondence: Jozef Hritz,
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Zhu P, Franklin R, Vogel A, Stanisheuski S, Reardon P, Sluchanko NN, Beckman JS, Karplus PA, Mehl RA, Cooley RB. PermaPhos Ser : autonomous synthesis of functional, permanently phosphorylated proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021:2021.10.22.465468. [PMID: 34931187 PMCID: PMC8687462 DOI: 10.1101/2021.10.22.465468] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Installing stable, functional mimics of phosphorylated amino acids into proteins offers a powerful strategy to study protein regulation. Previously, a genetic code expansion (GCE) system was developed to translationally install non-hydrolyzable phosphoserine (nhpSer), with the γ-oxygen replaced with carbon, but it has seen limited usage. Here, we achieve a 40-fold improvement in this system by engineering into Escherichia coli a biosynthetic pathway that produces nhpSer from the central metabolite phosphoenolpyruvate. Using this "PermaPhos Ser " system - an autonomous 21-amino acid E. coli expression system for incorporating nhpSer into target proteins - we show that nhpSer faithfully mimics the effects of phosphoserine in three stringent test cases: promoting 14-3-3/client complexation, disrupting 14-3-3 dimers, and activating GSK3β phosphorylation of the SARS-CoV-2 nucleocapsid protein. This facile access to nhpSer containing proteins should allow nhpSer to replace Asp and Glu as the go-to pSer phosphomimetic for proteins produced in E. coli .
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Affiliation(s)
- Phillip Zhu
- Oregon State University, Department of Biochemistry and Biophysics, 2011 Agricultural and Life Sciences, Corvallis, OR 97331
| | - Rachel Franklin
- Oregon State University, Department of Biochemistry and Biophysics, 2011 Agricultural and Life Sciences, Corvallis, OR 97331
| | - Amber Vogel
- Oregon State University, Department of Biochemistry and Biophysics, 2011 Agricultural and Life Sciences, Corvallis, OR 97331
| | - Stanislau Stanisheuski
- Oregon State University, Department of Chemistry, 153 Gilbert Hall, Oregon State University, Corvallis, Oregon 97331
| | - Patrick Reardon
- Oregon State University, Department of Biochemistry and Biophysics, 2011 Agricultural and Life Sciences, Corvallis, OR 97331
| | - Nikolai N. Sluchanko
- A.N. Bach Institute of Biochemistry, Federal Research Center of Biotechnology of the Russian Academy of Sciences, 119071, Moscow, Russia
| | - Joseph S. Beckman
- Oregon State University, Department of Biochemistry and Biophysics, 2011 Agricultural and Life Sciences, Corvallis, OR 97331
- e-MSion Inc., 2121 NE Jack London St, Corvallis, Oregon 97330
| | - P. Andrew Karplus
- Oregon State University, Department of Biochemistry and Biophysics, 2011 Agricultural and Life Sciences, Corvallis, OR 97331
| | - Ryan A. Mehl
- Oregon State University, Department of Biochemistry and Biophysics, 2011 Agricultural and Life Sciences, Corvallis, OR 97331
| | - Richard B. Cooley
- Oregon State University, Department of Biochemistry and Biophysics, 2011 Agricultural and Life Sciences, Corvallis, OR 97331
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Wu S, Shao M, Zhang Y, Shi D. Activation of RSK2 upregulates SOX8 to promote methotrexate resistance in gestational trophoblastic neoplasia. J Transl Med 2021; 101:1494-1504. [PMID: 34373588 DOI: 10.1038/s41374-021-00651-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 07/22/2021] [Accepted: 07/22/2021] [Indexed: 11/09/2022] Open
Abstract
Resistance to chemotherapy is frequently driven by aberrantly activated kinases in cancer. Herein, we characterized the global phosphoproteomic alterations associated with methotrexate (MTX) resistance in gestational trophoblastic neoplastic (GTN) cells. A total of 1111 phosphosites on 713 proteins were significantly changed, with highly elevated Ribosomal S6 Kinase 2 (RSK2) phosphorylation (pS227) observed in MTX-resistant GTN cells. Activation of RSK2 promoted cell proliferation and survival after MTX treatment in GTN cell models. Interestingly, RSK2 might play an important role in the regulation of reactive oxygen species (ROS) homeostasis, as manipulation of RSK2 activation affected ROS accumulation and SOX8 expression in GTN cells. In addition, overexpression of SOX8 partly rescued cell proliferation and survival in RSK2-depleted MTX-resistant GTN cells, suggesting that SOX8 might serve as a downstream effector of RSK2 to promote MTX resistance in GTN cells. Highly activated RSK2/SOX8 signaling was observed in MTX-resistant GTN specimens. Further, the RSK2 inhibitor BIX02565 effectively reduced SOX8 expression, induced ROS accumulation, and enhanced MTX-induced cytotoxicity in vitro and in vivo. Collectively, our findings suggested that RSK2 activation could promote MTX resistance via upregulating SOX8 and attenuating MTX-induced ROS in GTN cells, which may help to develop experimental therapeutics to treat MTX-resistant GTN.
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Affiliation(s)
- Shaobin Wu
- Department of General Surgery, Xiangya Hospital, Central South University, Changsha, China
| | - Mingjie Shao
- Department of General Surgery, Xiangya Hospital, Central South University, Changsha, China
| | - Yi Zhang
- Department of Gynecology, Xiangya Hospital, Central South University, Changsha, China
| | - Dazun Shi
- Department of Gynecology, Xiangya Hospital, Central South University, Changsha, China.
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