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Hou S, Wang J, Li W, Hao X, Hang Q. Roles of Integrins in Gastrointestinal Cancer Metastasis. Front Mol Biosci 2021; 8:708779. [PMID: 34869579 PMCID: PMC8634653 DOI: 10.3389/fmolb.2021.708779] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 10/08/2021] [Indexed: 12/12/2022] Open
Abstract
Integrins are a large family of heterodimeric transmembrane receptors which mediate cell adhesion and transmit signals to the cell interior. The mechanistic roles of integrins have long been an enigma in cancer, given its complexity in regulating different cellular behaviors. Recently, however, increasing research is providing new insights into its function and the underlying mechanisms, which collectively include the influences of altered integrin expression on the aberrant signaling pathways and cancer progression. Many studies have also demonstrated the potentiality of integrins as therapeutic targets in cancer treatment. In this review, we have summarized these recent reports and put a particular emphasis on the dysregulated expression of integrins and how they regulate related signaling pathways to facilitate the metastatic progression of gastrointestinal cancer, including gastric cancer (GC) and colorectal cancer (CRC), which will address the crucial roles of integrins in gastrointestinal cancer.
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Affiliation(s)
- Sicong Hou
- Department of Gastroenterology, Affiliated Hospital of Yangzhou University, Yangzhou University, Yangzhou, China
| | - Jiaxin Wang
- Department of Clinical Medicine, Medical College, Yangzhou University, Yangzhou, China
| | - Wenqian Li
- Department of Clinical Medicine, Medical College, Yangzhou University, Yangzhou, China
| | - Xin Hao
- Department of Clinical Medicine, Medical College, Yangzhou University, Yangzhou, China
| | - Qinglei Hang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States
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2
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Rocha MC, Minari K, Fabri JHTM, Kerkaert JD, Gava LM, da Cunha AF, Cramer RA, Borges JC, Malavazi I. Aspergillus fumigatus Hsp90 interacts with the main components of the cell wall integrity pathway and cooperates in heat shock and cell wall stress adaptation. Cell Microbiol 2021; 23:e13273. [PMID: 33010083 PMCID: PMC7855945 DOI: 10.1111/cmi.13273] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/12/2020] [Accepted: 09/27/2020] [Indexed: 12/18/2022]
Abstract
The initiation of Aspergillus fumigatus infection occurs via dormant conidia deposition into the airways. Therefore, conidial germination and subsequent hyphal extension and growth occur in a sustained heat shock (HS) environment promoted by the host. The cell wall integrity pathway (CWIP) and the essential eukaryotic chaperone Hsp90 are critical for fungi to survive HS. Although A. fumigatus is a thermophilic fungus, the mechanisms underpinning the HS response are not thoroughly described and important to define its role in pathogenesis, virulence and antifungal drug responses. Here, we investigate the contribution of the CWIP in A. fumigatus thermotolerance. We observed that the CWIP components PkcA, MpkA and RlmA are Hsp90 clients and that a PkcAG579R mutation abolishes this interaction. PkcAG579R also abolishes MpkA activation in the short-term response to HS. Biochemical and biophysical analyses indicated that Hsp90 is a dimeric functional ATPase, which has a higher affinity for ADP than ATP and prevents MpkA aggregation in vitro. Our data suggest that the CWIP is constitutively required for A. fumigatus to cope with the temperature increase found in the mammalian lung environment, emphasising the importance of this pathway in supporting thermotolerance and cell wall integrity.
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Affiliation(s)
- Marina Campos Rocha
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Karine Minari
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, Brazil
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | | | - Joshua D Kerkaert
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Lisandra Marques Gava
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Anderson Ferreira da Cunha
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, Brazil
| | - Robert A Cramer
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Júlio César Borges
- Instituto de Química de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | - Iran Malavazi
- Departamento de Genética e Evolução, Centro de Ciências Biológicas e da Saúde, Universidade Federal de São Carlos, São Carlos, Brazil
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3
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Misiura MM, Kolomeisky AB. Role of Intrinsically Disordered Regions in Acceleration of Protein–Protein Association. J Phys Chem B 2019; 124:20-27. [DOI: 10.1021/acs.jpcb.9b08793] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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4
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Kaoud TS, Johnson WH, Ebelt ND, Piserchio A, Zamora-Olivares D, Van Ravenstein SX, Pridgen JR, Edupuganti R, Sammons R, Cano M, Warthaka M, Harger M, Tavares CDJ, Park J, Radwan MF, Ren P, Anslyn EV, Tsai KY, Ghose R, Dalby KN. Modulating multi-functional ERK complexes by covalent targeting of a recruitment site in vivo. Nat Commun 2019; 10:5232. [PMID: 31745079 PMCID: PMC6863825 DOI: 10.1038/s41467-019-12996-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Accepted: 10/10/2019] [Indexed: 12/31/2022] Open
Abstract
Recently, the targeting of ERK with ATP-competitive inhibitors has emerged as a potential clinical strategy to overcome acquired resistance to BRAF and MEK inhibitor combination therapies. In this study, we investigate an alternative strategy of targeting the D-recruitment site (DRS) of ERK. The DRS is a conserved region that lies distal to the active site and mediates ERK-protein interactions. We demonstrate that the small molecule BI-78D3 binds to the DRS of ERK2 and forms a covalent adduct with a conserved cysteine residue (C159) within the pocket and disrupts signaling in vivo. BI-78D3 does not covalently modify p38MAPK, JNK or ERK5. BI-78D3 promotes apoptosis in BRAF inhibitor-naive and resistant melanoma cells containing a BRAF V600E mutation. These studies provide the basis for designing modulators of protein-protein interactions involving ERK, with the potential to impact ERK signaling dynamics and to induce cell cycle arrest and apoptosis in ERK-dependent cancers.
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Affiliation(s)
- Tamer S Kaoud
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA.,Department of Medicinal Chemistry, Faculty of Pharmacy, Minia University, Minia, 61519, Egypt
| | - William H Johnson
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Nancy D Ebelt
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Andrea Piserchio
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY, USA
| | | | - Sabrina X Van Ravenstein
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Jacey R Pridgen
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Ramakrishna Edupuganti
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Rachel Sammons
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Micael Cano
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Mangalika Warthaka
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Matthew Harger
- Biomedical Engineering Department, The University of Texas at Austin, Austin, TX, USA
| | - Clint D J Tavares
- Department of Cancer Biology, Dana-Farber Cancer Institute and Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Jihyun Park
- The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Mohamed F Radwan
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
| | - Pengyu Ren
- Biomedical Engineering Department, The University of Texas at Austin, Austin, TX, USA
| | - Eric V Anslyn
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA
| | | | - Ranajeet Ghose
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY, USA.,Graduate Programs in Biochemistry, Chemistry and Physics, The Graduate Center of the City University of New York, New York, NY, 10016, USA
| | - Kevin N Dalby
- Division of Chemical Biology and Medicinal Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA.
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5
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Sammons RM, Perry NA, Li Y, Cho EJ, Piserchio A, Zamora-Olivares DP, Ghose R, Kaoud TS, Debevec G, Bartholomeusz C, Gurevich VV, Iverson TM, Giulianotti M, Houghten RA, Dalby KN. A Novel Class of Common Docking Domain Inhibitors That Prevent ERK2 Activation and Substrate Phosphorylation. ACS Chem Biol 2019; 14:1183-1194. [PMID: 31058487 DOI: 10.1021/acschembio.9b00093] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Extracellular signal-regulated kinases (ERK1/2) are mitogen-activated protein kinases (MAPKs) that play a pro-tumorigenic role in numerous cancers. ERK1/2 possess two protein-docking sites that are distinct from the active site: the D-recruitment site (DRS) and the F-recruitment site. These docking sites facilitate substrate recognition, intracellular localization, signaling specificity, and protein complex assembly. Targeting these sites on ERK in a therapeutic context may overcome many problems associated with traditional ATP-competitive inhibitors. Here, we identified a new class of inhibitors that target the ERK DRS by screening a synthetic combinatorial library of more than 30 million compounds. The screen detects the competitive displacement of a fluorescent peptide from the DRS of ERK2. The top molecular scaffold from the screen was optimized for structure-activity relationship by positional scanning of different functional groups. This resulted in 10 compounds with similar binding affinities and a shared core structure consisting of a tertiary amine hub with three functionalized cyclic guanidino branches. Compound 2507-1 inhibited ERK2 from phosphorylating a DRS-targeting substrate and prevented the phosphorylation of ERK2 by a constitutively active MEK1 (MAPK/ERK kinase 1) mutant. Interaction between an analogue, 2507-8, and the ERK2 DRS was confirmed by nuclear magnetic resonance and X-ray crystallography. 2507-8 forms critical interactions at the common docking domain residue Asp319 via an arginine-like moiety that is shared by all 10 hits, suggesting a common binding mode. The structural and biochemical insights reported here provide the basis for developing new ERK inhibitors that are not ATP-competitive but instead function by disrupting critical protein-protein interactions.
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Affiliation(s)
| | | | - Yangmei Li
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida 34987, United States
- Department of Drug Discovery & Biomedical Sciences, University of South Carolina, Columbia, South Carolina 29208, United States
| | | | - Andrea Piserchio
- Department of Chemistry and Biochemistry, The City College of New York, New York, New York 10031, United States
| | | | - Ranajeet Ghose
- Department of Chemistry and Biochemistry, The City College of New York, New York, New York 10031, United States
| | - Tamer S. Kaoud
- Department of Medicinal Chemistry, Faculty of Pharmacy, Minia University, 61519 Minia, Egypt
| | - Ginamarie Debevec
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida 34987, United States
| | | | | | | | - Marc Giulianotti
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida 34987, United States
| | - Richard A. Houghten
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, Florida 34987, United States
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6
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Sammons RM, Ghose R, Tsai KY, Dalby KN. Targeting ERK beyond the boundaries of the kinase active site in melanoma. Mol Carcinog 2019; 58:1551-1570. [PMID: 31190430 DOI: 10.1002/mc.23047] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 04/30/2019] [Accepted: 05/10/2019] [Indexed: 12/14/2022]
Abstract
Extracellular signal-regulated kinase 1/2 (ERK1/2) constitute a point of convergence for complex signaling events that regulate essential cellular processes, including proliferation and survival. As such, dysregulation of the ERK signaling pathway is prevalent in many cancers. In the case of BRAF-V600E mutant melanoma, ERK inhibition has emerged as a viable clinical approach to abrogate signaling through the ERK pathway, even in cases where MEK and Raf inhibitor treatments fail to induce tumor regression due to resistance mechanisms. Several ERK inhibitors that target the active site of ERK have reached clinical trials, however, many critical ERK interactions occur at other potentially druggable sites on the protein. Here we discuss the role of ERK signaling in cell fate, in driving melanoma, and in resistance mechanisms to current BRAF-V600E melanoma treatments. We explore targeting ERK via a distinct site of protein-protein interaction, known as the D-recruitment site (DRS), as an alternative or supplementary mode of ERK pathway inhibition in BRAF-V600E melanoma. Targeting the DRS with inhibitors in melanoma has the potential to not only disrupt the catalytic apparatus of ERK but also its noncatalytic functions, which have significant impacts on spatiotemporal signaling dynamics and cell fate.
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Affiliation(s)
- Rachel M Sammons
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas.,Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, Texas
| | - Ranajeet Ghose
- Department of Chemistry and Biochemistry, The City College of New York, New York, New York
| | - Kenneth Y Tsai
- Departments of Anatomic Pathology and Tumor Biology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Kevin N Dalby
- Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, Texas.,Department of Oncology, Dell Medical School, The University of Texas at Austin, Austin, Texas
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7
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Local destabilization, rigid body, and fuzzy docking facilitate the phosphorylation of the transcription factor Ets-1 by the mitogen-activated protein kinase ERK2. Proc Natl Acad Sci U S A 2017; 114:E6287-E6296. [PMID: 28716922 DOI: 10.1073/pnas.1702973114] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mitogen-activated protein (MAP) kinase substrates are believed to require consensus docking motifs (D-site, F-site) to engage and facilitate efficient site-specific phosphorylation at specific serine/threonine-proline sequences by their cognate kinases. In contrast to other MAP kinase substrates, the transcription factor Ets-1 has no canonical docking motifs, yet it is efficiently phosphorylated by the MAP kinase ERK2 at a consensus threonine site (T38). Using NMR methodology, we demonstrate that this phosphorylation is enabled by a unique bipartite mode of ERK2 engagement by Ets-1 and involves two suboptimal noncanonical docking interactions instead of a single canonical docking motif. The N terminus of Ets-1 interacts with a part of the ERK2 D-recruitment site that normally accommodates the hydrophobic sidechains of a canonical D-site, retaining a significant degree of disorder in its ERK2-bound state. In contrast, the C-terminal region of Ets-1, including its Pointed (PNT) domain, engages in a largely rigid body interaction with a section of the ERK2 F-recruitment site through a binding mode that deviates significantly from that of a canonical F-site. This latter interaction is notable for the destabilization of a flexible helix that bridges the phospho-acceptor site to the rigid PNT domain. These two spatially distinct, individually weak docking interactions facilitate the highly specific recognition of ERK2 by Ets-1, and enable the optimal localization of its dynamic phospho-acceptor T38 at the kinase active site to enable efficient phosphorylation.
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8
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Misiura MM, Kolomeisky AB. Theoretical Investigation of the Mechanisms of ERK2 Enzymatic Catalysis. J Phys Chem B 2016; 120:10508-10514. [PMID: 27649451 DOI: 10.1021/acs.jpcb.6b08435] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
ERK2 are protein kinases that during the enzymatic catalysis, in contrast to traditional enzymes, utilize additional interactions with substrates outside of the active sites. It is widely believed that these docking interactions outside of the enzymatic pockets enhance the specificity of these proteins. However, the molecular mechanisms of how the docking interactions affect the catalysis remain not well understood. Here, we develop a simple theoretical approach to analyze the enzymatic catalysis in ERK2 proteins. Our method is based on first-passage process analysis, and it provides explicit expressions for all dynamic properties of the system. It is found that there are specific binding energies for substrates in docking and catalytic domains that lead to maximal enzymatic reaction rates. Thus, we propose that the role of the docking interactions is not only to increase the enzymatic specificity but also to optimize the dynamics of the catalytic process. Our theoretical results are utilized to describe experimental observations on ERK2 enzymatic activities.
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Affiliation(s)
- Mikita M Misiura
- Department of Chemistry and Center for Theoretical Biological Physics, Rice University , Houston, Texas 77005, United States
| | - Anatoly B Kolomeisky
- Department of Chemistry and Center for Theoretical Biological Physics, Rice University , Houston, Texas 77005, United States
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9
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Buscà R, Pouysségur J, Lenormand P. ERK1 and ERK2 Map Kinases: Specific Roles or Functional Redundancy? Front Cell Dev Biol 2016; 4:53. [PMID: 27376062 PMCID: PMC4897767 DOI: 10.3389/fcell.2016.00053] [Citation(s) in RCA: 175] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 05/17/2016] [Indexed: 12/22/2022] Open
Abstract
The MAP kinase signaling cascade Ras/Raf/MEK/ERK has been involved in a large variety of cellular and physiological processes that are crucial for life. Many pathological situations have been associated to this pathway. More than one isoform has been described at each level of the cascade. In this review we devoted our attention to ERK1 and ERK2, which are the effector kinases of the pathway. Whether ERK1 and ERK2 specify functional differences or are in contrast functionally redundant, constitutes an ongoing debate despite the huge amount of studies performed to date. In this review we compiled data on ERK1 vs. ERK2 gene structures, protein sequences, expression levels, structural and molecular mechanisms of activation and substrate recognition. We have also attempted to perform a rigorous analysis of studies regarding the individual roles of ERK1 and ERK2 by the means of morpholinos, siRNA, and shRNA silencing as well as gene disruption or gene replacement in mice. Finally, we comment on a recent study of gene and protein evolution of ERK isoforms as a distinct approach to address the same question. Our review permits the evaluation of the relevance of published studies in the field especially when measurements of global ERK activation are taken into account. Our analysis favors the hypothesis of ERK1 and ERK2 exhibiting functional redundancy and points to the concept of the global ERK quantity, and not isoform specificity, as being the essential determinant to achieve ERK function.
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Affiliation(s)
- Roser Buscà
- Centre National de la Recherche Scientifique UMR7284, Institut National de la Santé et de la Recherche Médicale, Centre A. Lacassagne, Institute for Research on Cancer and Ageing of Nice, University of Nice-Sophia Antipolis Nice, France
| | - Jacques Pouysségur
- Centre National de la Recherche Scientifique UMR7284, Institut National de la Santé et de la Recherche Médicale, Centre A. Lacassagne, Institute for Research on Cancer and Ageing of Nice, University of Nice-Sophia AntipolisNice, France; Centre Scientifique de MonacoMonaco, Monaco
| | - Philippe Lenormand
- Centre National de la Recherche Scientifique UMR7284, Institut National de la Santé et de la Recherche Médicale, Centre A. Lacassagne, Institute for Research on Cancer and Ageing of Nice, University of Nice-Sophia Antipolis Nice, France
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10
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Peng C, Li Z, Niu Z, Niu W, Xu Z, Gao H, Niu W, Wang J, He Z, Gao C, Lin P, Agrez M, Zhang Z, Niu J. Norcantharidin Suppresses Colon Cancer Cell Epithelial-Mesenchymal Transition by Inhibiting the αvβ6-ERK-Ets1 Signaling Pathway. Sci Rep 2016; 6:20500. [PMID: 26846153 PMCID: PMC4742802 DOI: 10.1038/srep20500] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 01/05/2016] [Indexed: 12/30/2022] Open
Abstract
Norcantharidin (NCTD) is an efficacious anti-cancer drug that has been used in China for many years, but its underlying mechanism of action is still not fully understood. In the present study, we found that NCTD could induce morphological changes in colon cancer cells, causing a transition from a spindle-shaped morphology to a typical round or oval shape, which was indicative of a mesenchymal-epithelial transition (MET) process. Next, we investigated the mechanism by which NCTD induced the MET process. Using a transwell assay, we found that NCTD could suppress the migratory and invasive ability of colon cancer cells in a dose-dependent manner. Moreover, NCTD suppressed the expression of integrin αvβ6, MMP-3, and MMP-9 as well as the polymerization of F-actin, further supporting its suppressive effect on migratory and invasive ability. Furthermore, the expression of αvβ6, N-cadherin, vimentin and phosphorylated ERK was decreased, while the expression of E-cadherin was up-regulated. We verified that phosphorylated Ets1 was down-regulated substantially after treatment with NCTD. Taken together, our data demonstrated that NCTD could inhibit the EMT process of colon cancer cells by inhibiting the αvβ6-ERK-Ets1 signaling pathway. This study revealed part of the mechanism through which NCTD could reverse the EMT process in colon cancer.
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Affiliation(s)
- Cheng Peng
- Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Zequn Li
- Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Zhengchuan Niu
- Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Wei Niu
- Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Zongquan Xu
- Department of Hepatic Oncology, Jiangxi Provincial Cancer Hospital, Nanchang, Jiangxi, China
| | - Huijie Gao
- Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Weibo Niu
- Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - JiaYong Wang
- Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Zhaobin He
- Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Chao Gao
- Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Pengfei Lin
- Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Michael Agrez
- Newcastle Bowel Cancer Research Collaborative, The University of Newcastle, Callaghan, New South Wales, Australia
| | - Zongli Zhang
- Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Jun Niu
- Department of General Surgery, Qilu Hospital, Shandong University, Jinan, Shandong, China
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11
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Patel TR, Winzor DJ, Scott DJ. Analytical ultracentrifugation: A versatile tool for the characterisation of macromolecular complexes in solution. Methods 2016; 95:55-61. [DOI: 10.1016/j.ymeth.2015.11.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 11/05/2015] [Accepted: 11/07/2015] [Indexed: 12/25/2022] Open
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12
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Dittmer J. The role of the transcription factor Ets1 in carcinoma. Semin Cancer Biol 2015; 35:20-38. [PMID: 26392377 DOI: 10.1016/j.semcancer.2015.09.010] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/16/2015] [Accepted: 09/16/2015] [Indexed: 12/12/2022]
Abstract
Ets1 belongs to the large family of the ETS domain family of transcription factors and is involved in cancer progression. In most carcinomas, Ets1 expression is linked to poor survival. In breast cancer, Ets1 is primarily expressed in the triple-negative subtype, which is associated with unfavorable prognosis. Ets1 contributes to the acquisition of cancer cell invasiveness, to EMT (epithelial-to-mesenchymal transition), to the development of drug resistance and neo-angiogenesis. The aim of this review is to summarize the current knowledge on the functions of Ets1 in carcinoma progression and on the mechanisms that regulate Ets1 activity in cancer.
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Affiliation(s)
- Jürgen Dittmer
- Clinic for Gynecology, Martin Luther University Halle-Wittenberg, Germany.
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13
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Structural and Dynamic Features of F-recruitment Site Driven Substrate Phosphorylation by ERK2. Sci Rep 2015; 5:11127. [PMID: 26054059 PMCID: PMC4459106 DOI: 10.1038/srep11127] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/18/2015] [Indexed: 02/07/2023] Open
Abstract
The F-recruitment site (FRS) of active ERK2 binds F-site (Phe-x-Phe-Pro) sequences found downstream of the Ser/Thr phospho-acceptor on cellular substrates. Here we apply NMR methods to analyze the interaction between active ERK2 (ppERK2), and a 13-residue F-site-bearing peptide substrate derived from its cellular target, the transcription factor Elk-1. Our results provide detailed insight into previously elusive structural and dynamic features of FRS/F-site interactions and FRS-driven substrate phosphorylation. We show that substrate F-site engagement significantly quenches slow dynamics involving the ppERK2 activation-loop and the FRS. We also demonstrate that the F-site phenylalanines make critical contacts with ppERK2, in contrast to the proline whose cis-trans isomerization has no significant effect on F-site recognition by the kinase FRS. Our results support a mechanism where phosphorylation of the disordered N-terminal phospho-acceptor is facilitated by its increased productive encounters with the ppERK2 active site due to docking of the proximal F-site at the kinase FRS.
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14
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He J, Gong J, Ding Q, Tan Q, Han P, Liu J, Zhou Z, Tu W, Xia Y, Yan W, Tian D. Suppressive effect of SATB1 on hepatic stellate cell activation and liver fibrosis in rats. FEBS Lett 2015; 589:1359-68. [PMID: 25896016 DOI: 10.1016/j.febslet.2015.04.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Revised: 03/24/2015] [Accepted: 04/08/2015] [Indexed: 12/13/2022]
Abstract
Liver fibrosis is a worldwide clinical issue. Activation of hepatic stellate cells (HSCs) is the central event during liver fibrosis. We investigated the role of SATB1 in HSC activation and liver fibrogenesis. The results show that SATB1 expression is reduced during HSC activation. Additionally, SATB1 inhibits HSC activation, proliferation, migration, and collagen synthesis. Furthermore, CTGF, a pro-fibrotic agent, is also significantly inhibited by SATB1 through the Ras/Raf-1/MEK/ERK/Ets-1 pathway. In vivo, SATB1 deactivates HSCs and attenuates fibrosis in TAA-induced fibrotic rat livers. These data indicate that SATB1 plays an important role in HSC activation and liver fibrosis.
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Affiliation(s)
- Jiayi He
- Department of Gastroenterology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jin Gong
- Department of Gastroenterology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qiang Ding
- Department of Gastroenterology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qinghai Tan
- Department of Gastroenterology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ping Han
- Department of Gastroenterology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jingmei Liu
- Department of Gastroenterology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhenzhen Zhou
- Department of Gastroenterology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Tu
- Department of Gastroenterology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yujia Xia
- Department of Gastroenterology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Yan
- Department of Gastroenterology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | - Dean Tian
- Department of Gastroenterology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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15
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Wang WK, Lu QH, Zhang JN, Wang B, Liu XJ, An FS, Qin WD, Chen XY, Dong WQ, Zhang C, Zhang Y, Zhang MX. HMGB1 mediates hyperglycaemia-induced cardiomyocyte apoptosis via ERK/Ets-1 signalling pathway. J Cell Mol Med 2014; 18:2311-20. [PMID: 25210949 PMCID: PMC4224563 DOI: 10.1111/jcmm.12399] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Accepted: 07/07/2014] [Indexed: 02/05/2023] Open
Abstract
Apoptosis is a key event involved in diabetic cardiomyopathy. The expression of high mobility group box 1 protein (HMGB1) is up-regulated in diabetic mice. However, the molecular mechanism of high glucose (HG)-induced cardiomyocyte apoptosis remains obscure. We aimed to determine the role of HMGB1 in HG-induced apoptosis of cardiomyocytes. Treating neonatal primary cardiomyocytes with HG increased cell apoptosis, which was accompanied by elevated levels of HMGB1. Inhibition of HMGB1 by short-hairpin RNA significantly decreased HG-induced cell apoptosis by reducing caspase-3 activation and ratio of Bcl2-associated X protein to B-cell lymphoma/leukemia-2 (bax/bcl-2). Furthermore, HG activated E26 transformation-specific sequence-1 (Ets-1), and HMGB1 inhibition attenuated HG-induced activation of Ets-1 via extracellular signal-regulated kinase 1/2 (ERK1/2) signalling. In addition, inhibition of Ets-1 significantly decreased HG-induced cardiomyocyte apoptosis. Similar results were observed in streptozotocin-treated diabetic mice. Inhibition of HMGB1 by short-hairpin RNA markedly decreased myocardial cell apoptosis and activation of ERK and Ets-1 in diabetic mice. In conclusion, inhibition of HMGB1 may protect against hyperglycaemia-induced cardiomyocyte apoptosis by down-regulating ERK-dependent activation of Ets-1.
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Affiliation(s)
- Wen-Ke Wang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Public Health, Qilu Hospital of Shandong University, Jinan, Shandong, China
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16
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Sun Q, Sun F, Wang B, Liu S, Niu W, Liu E, Peng C, Wang J, Gao H, Liang B, Niu Z, Zou X, Niu J. Interleukin-8 promotes cell migration through integrin αvβ6 upregulation in colorectal cancer. Cancer Lett 2014; 354:245-53. [PMID: 25150782 DOI: 10.1016/j.canlet.2014.08.021] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 08/01/2014] [Accepted: 08/14/2014] [Indexed: 01/05/2023]
Abstract
Colorectal cancer (CRC), which is notorious for high morbidity and mortality around the world, shows a predilection for metastasis to liver. Interleukin-8 (IL-8), a chemokine with a defining CXC amino acid motif, has been reported to promote CRC cell migration and is associated with poor prognosis of CRC. However, the underlying molecular mechanism of IL-8-mediated migration remains obscure. In this study, we first demonstrated the cross talk between IL-8 and integrin αvβ6. We analyzed 139 human CRC samples, and found that the immunohistochemical expression of αvβ6 was significantly correlated with expression of IL-8. Furthermore, IL-8 increased the migration through integrin αvβ6 in human CRC cells, and both CXCR1 and CXCR2 were primarily involved during the process. IL-8 upregulated αvβ6 expression in a dose-dependent manner through activation of ERK and Ets-1 signaling pathway. Taken together, our results indicated that IL-8 enhances the migration of CRC cells by increasing αvβ6 integrin expression through the ERK/Ets-1 pathway. Targeting integrin αvβ6 in IL-8 expressing tumors might be a potential therapeutic strategy for CRC patients.
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Affiliation(s)
- Qi Sun
- Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China; Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Public Health, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China
| | - Fengkai Sun
- Department of Hepatology, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China
| | - Ben Wang
- Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China; Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Public Health, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China
| | - Song Liu
- Department of Thyroid and Breast Surgery, Affiliated Hospital of Binzhou Medical College, Binzhou 256603, Shandong, China
| | - Weibo Niu
- Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China
| | - Enyu Liu
- Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China
| | - Cheng Peng
- Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China
| | - Jiayong Wang
- Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China
| | - Huijie Gao
- Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China; Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Public Health, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China
| | - Benjia Liang
- Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China; Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Public Health, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China
| | - Zhengchuan Niu
- Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China; Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Public Health, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China
| | - Xueqing Zou
- Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China; Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Public Health, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China
| | - Jun Niu
- Department of Hepatobiliary Surgery, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China.
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17
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Halling DB, Kenrick SA, Riggs AF, Aldrich RW. Calcium-dependent stoichiometries of the KCa2.2 (SK) intracellular domain/calmodulin complex in solution. ACTA ACUST UNITED AC 2014; 143:231-52. [PMID: 24420768 PMCID: PMC4001768 DOI: 10.1085/jgp.201311007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Biophysical analyses indicate that the Ca2+-activated K+ channel SK2 binds calmodulin with multiple stoichiometries, distinct from the two SK2-two calmodulin stoichiometry identified by crystallography. Ca2+ activates SK Ca2+-activated K+ channels through the protein Ca2+ sensor, calmodulin (CaM). To understand how SK channels operate, it is necessary to determine how Ca2+ regulates CaM binding to its target on SK. Tagless, recombinant SK peptide (SKp), was purified for binding studies with CaM at low and high Ca2+ concentrations. Composition gradient multi-angle light scattering accurately measures the molar mass, stoichiometry, and affinity of protein complexes. In 2 mM Ca2+, SKp and CaM bind with three different stoichiometries that depend on the molar ratio of SKp:CaM in solution. These complexes include 28 kD 1SKp/1CaM, 39 kD 2SKp/1CaM, and 44 kD 1SKp/2CaM. A 2SKp/2CaM complex, observed in prior crystallographic studies, is absent. At <5 nM Ca2+, 1SKp/1CaM and 2SKp/1CaM were observed; however, 1SKp/2CaM was absent. Analytical ultracentrifugation was used to characterize the physical properties of the three SKp/CaM stoichiometries. In high Ca2+, the sedimentation coefficient is smaller for a 1SKp:1CaM solution than it is for either 2SKp:1CaM or 1SKp:2CaM. At low Ca2+ and at >100 µM protein concentrations, a molar excess of SKp over CaM causes aggregation. Aggregation is not observed in Ca2+ or with CaM in molar excess. In low Ca2+ both 1SKp:1CaM and 1SKp:2CaM solutions have similar sedimentation coefficients, which is consistent with the absence of a 1SKp/2CaM complex in low Ca2+. These results suggest that complexes with stoichiometries other than 2SKp/2CaM are important in gating.
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Affiliation(s)
- D Brent Halling
- Department of Neuroscience, 2 Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712
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18
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Wang B, Wang W, Niu W, Liu E, Liu X, Wang J, Peng C, Liu S, Xu L, Wang L, Niu J. SDF-1/CXCR4 axis promotes directional migration of colorectal cancer cells through upregulation of integrin αvβ6. Carcinogenesis 2013; 35:282-91. [PMID: 24085800 DOI: 10.1093/carcin/bgt331] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Colorectal cancer (CRC) displays a predilection for metastasis to liver. Although stromal cell-derived factor-1 (SDF-1)/CXCR4 plays an important role in the liver metastasis, the molecular mechanism still remains obscure. We previously reported that integrin αvβ6 was implicated in the progression of CRC. However, no data are currently available on the cross talk between CXCR4 and αvβ6. In the present study, we first demonstrated the cross talk between CXCR4 and αvβ6 and their role in liver metastasis of CRC. We analyzed 159 human CRC samples and found that expression of CXCR4 and αvβ6 was significantly associated with liver metastasis, and interestingly expression of αvβ6 significantly correlated with expression of CXCR4. Both CXCR4 and αvβ6 were highly expressed in metastatic CRC cell lines HT-29 and WiDr, whereas both of them were exiguous in non-metastatic cell line Caco-2. Furthermore, inhibition of αvβ6 significantly decreased SDF-1α-induced cell migration in vitro. SDF-1/CXCR4 could upregulate αvβ6 expression through phosphorylation of ERK and activation of Ets-1 transcription factor. In conclusion, we demonstrate that SDF-1/CXCR4 induces directional migration and liver metastasis of CRC cells by upregulating αvβ6 through ERK/Ets-1 pathway. These data support combined inhibition of CXCR4 and αvβ6 to prevent development of liver metastasis of CRC.
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Affiliation(s)
- Ben Wang
- Department of Hepatobiliary Surgery
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19
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Tzarum N, Komornik N, Ben Chetrit D, Engelberg D, Livnah O. DEF pocket in p38α facilitates substrate selectivity and mediates autophosphorylation. J Biol Chem 2013; 288:19537-47. [PMID: 23671282 DOI: 10.1074/jbc.m113.464511] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Signaling processes are primarily promoted by molecular recognition and corresponding protein-protein interactions. One of the key eukaryotic signaling pathways is the MAP kinase cascade involved in vital cellular processes such as cell proliferation, differentiation, apoptosis, and stress response. The principle recognition site of MAP kinases, the common docking (CD) region, forms selective interactions with substrates, upstream activators, and phosphatases. A second docking site, defined as the DEF site interaction pocket (DEF pocket), is formed subsequent to ERK2 and p38α activation. Both crystal structures of p38α in its dually phosphorylated form and of intrinsically active mutants showed the DEF pocket, giving motivation for studying its role in substrate activation and selectivity. Mutating selected DEF pocket residues significantly decreased the phosphorylation levels of three p38α substrates (ATFII, Elk-1, and MBP) with no apparent effect on the phosphorylation of MK2 kinase. Conversely, mutating the CD region gave the opposite effect, suggesting p38α substrates can be classified into DEF-dependent and DEF-independent substrates. In addition, mutating DEF pocket residues decreased the autophosphorylation capability of intrinsically active p38α mutants, suggesting DEF-mediated trans-autophosphorylation in p38α. These results could contribute to understanding substrate selectivity of p38α and serve as a platform for designing p38α-selective DEF site blockers, which partially inhibit p38α binding DEF-dependent substrates, whereas maintaining its other functions intact. In this context, preliminary results using synthetic peptides reveal significant inhibition of substrate phosphorylation by activated p38α.
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Affiliation(s)
- Netanel Tzarum
- Department of Biological Chemistry, The Alexander Silverman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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20
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Tsai T, Klausmeyer A, Conrad R, Gottschling C, Leo M, Faissner A, Wiese S. 7,8-Dihydroxyflavone leads to survival of cultured embryonic motoneurons by activating intracellular signaling pathways. Mol Cell Neurosci 2013; 56:18-28. [PMID: 23500004 DOI: 10.1016/j.mcn.2013.02.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 01/25/2013] [Accepted: 02/27/2013] [Indexed: 01/19/2023] Open
Abstract
Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family and a ligand for the tropomyosin-receptor kinase B (TrkB), mediates neuronal survival, differentiation, and synaptic plasticity. However, BDNF is not used to treat neurodegenerative diseases because of its poor pharmacokinetic profile, side effects, and absence of survival properties in clinical trials. Consequently, alternative approaches such as TrkB receptor agonist application are gaining importance. 7,8-Dihydroxyflavone (7,8-DHF), a member of the flavonoid family, has been described as a robust TrkB receptor agonist in hippocampal neurons. Nevertheless, the influence of 7,8-DHF on motoneurons, one of the main targets of BDNF in vivo, is so far unknown. Therefore, we investigated the impact of 7,8-DHF treatment on primary cultured mouse motoneurons. Indeed, we found an activation of the TrkB receptor. Moreover, 7,8-DHF application promotes survival and neurite growth of cultured motoneurons and these effects appear dose-dependent. To investigate the PI3K/AKT and MAPK pathway activation in 7,8-DHF treated motoneurons, we developed a high-density culture system of primary mouse motoneurons. Analysis of both pathways demonstrated a PI3K/AKT but not MAPK pathway activation in cultured motoneurons. This is in contrast to previously published reports about BDNF-mediated activation of TrkB. The lack of MAPK pathway activation is also in contrast to what has been found for hippocampal neurons that indeed show MAPK activation after 7,8-DHF treatment. The ability of 7,8-DHF to imitate BDNF function in motoneurons by using Trk receptor signaling would provide a new approach for the treatment of motoneuron diseases, but needs a more detailed analysis of the activation profile of 7,8-DHF.
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Affiliation(s)
- Teresa Tsai
- Institute for Cellmorphology and molecular Neurobiology, Group for molecular Cell biology, Universitaetsstrasse 150, Ruhr-University Bochum, Germany
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21
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Lau DKW, Okon M, McIntosh LP. The PNT domain from Drosophila pointed-P2 contains a dynamic N-terminal helix preceded by a disordered phosphoacceptor sequence. Protein Sci 2012; 21:1716-25. [PMID: 22936607 DOI: 10.1002/pro.2151] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 08/22/2012] [Accepted: 08/27/2012] [Indexed: 11/06/2022]
Abstract
Pointed-P2, the Drosophila ortholog of human ETS1 and ETS2, is a transcription factor involved in Ras/MAP kinase-regulated gene expression. In addition to a DNA-binding ETS domain, Pointed-P2 contains a PNT (or SAM) domain that serves as a docking module to enhance phosphorylation of an adjacent phosphoacceptor threonine by the ERK2 MAP kinase Rolled. Using NMR chemical shift, ¹⁵N relaxation, and amide hydrogen exchange measurements, we demonstrate that the Pointed-P2 PNT domain contains a dynamic N-terminal helix H0 appended to a core conserved five-helix bundle diagnostic of the SAM domain fold. Neither the secondary structure nor dynamics of the PNT domain is perturbed significantly upon in vitro ERK2 phosphorylation of three threonine residues in a disordered sequence immediately preceding this domain. These data thus confirm that the Drosophila Pointed-P2 PNT domain and phosphoacceptors are highly similar to those of the well-characterized human ETS1 transcription factor. NMR-monitored titrations also revealed that the phosphoacceptors and helix H0, as well as region of the core helical bundle identified previously by mutational analyses as a kinase docking site, are selectively perturbed upon ERK2 binding by Pointed-P2. Based on a homology model derived from the ETS1 PNT domain, helix H0 is predicted to partially occlude the docking interface. Therefore, this dynamic helix must be displaced to allow both docking of the kinase, as well as binding of Mae, a Drosophila protein that negatively regulates Pointed-P2 by competing with the kinase for its docking site.
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Affiliation(s)
- Desmond K W Lau
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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22
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Schnieders MJ, Kaoud TS, Yan C, Dalby KN, Ren P. Computational insights for the discovery of non-ATP competitive inhibitors of MAP kinases. Curr Pharm Des 2012; 18:1173-85. [PMID: 22316156 DOI: 10.2174/138161212799436368] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 12/06/2011] [Indexed: 12/22/2022]
Abstract
Due to their role in cellular signaling mitogen activated protein (MAP) kinases represent targets of pharmaceutical interest. However, the majority of known MAP kinase inhibitors compete with cellular ATP and target an ATP binding pocket that is highly conserved in the 500 plus representatives of the human protein kinase family. Here we review progress toward the development of non-ATP competitive MAP kinase inhibitors for the extracellular signal regulated kinases (ERK1/2), the c-jun N-terminal kinases (JNK1/2/3) and the p38 MAPKs (α, β, γ, and δ). Special emphasis is placed on the role of computational methods in the drug discovery process for MAP kinases. Topics include recent advances in X-ray crystallography theory that improve the MAP kinase structures essential to structurebased drug discovery, the use of molecular dynamics to understand the conformational heterogeneity of the activation loop and inhibitors discovered by virtual screening. The impact of an advanced polarizable force field such as AMOEBA used in conjunction with sophisticated kinetic and thermodynamic simulation methods is also discussed.
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Affiliation(s)
- Michael J Schnieders
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712, USA.
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23
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ERK1/2 MAP kinases: structure, function, and regulation. Pharmacol Res 2012; 66:105-43. [PMID: 22569528 DOI: 10.1016/j.phrs.2012.04.005] [Citation(s) in RCA: 1099] [Impact Index Per Article: 91.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 04/20/2012] [Indexed: 11/21/2022]
Abstract
ERK1 and ERK2 are related protein-serine/threonine kinases that participate in the Ras-Raf-MEK-ERK signal transduction cascade. This cascade participates in the regulation of a large variety of processes including cell adhesion, cell cycle progression, cell migration, cell survival, differentiation, metabolism, proliferation, and transcription. MEK1/2 catalyze the phosphorylation of human ERK1/2 at Tyr204/187 and then Thr202/185. The phosphorylation of both tyrosine and threonine is required for enzyme activation. Whereas the Raf kinase and MEK families have narrow substrate specificity, ERK1/2 catalyze the phosphorylation of hundreds of cytoplasmic and nuclear substrates including regulatory molecules and transcription factors. ERK1/2 are proline-directed kinases that preferentially catalyze the phosphorylation of substrates containing a Pro-Xxx-Ser/Thr-Pro sequence. Besides this primary structure requirement, many ERK1/2 substrates possess a D-docking site, an F-docking site, or both. A variety of scaffold proteins including KSR1/2, IQGAP1, MP1, β-Arrestin1/2 participate in the regulation of the ERK1/2 MAP kinase cascade. The regulatory dephosphorylation of ERK1/2 is mediated by protein-tyrosine specific phosphatases, protein-serine/threonine phosphatases, and dual specificity phosphatases. The combination of kinases and phosphatases make the overall process reversible. The ERK1/2 catalyzed phosphorylation of nuclear transcription factors including those of Ets, Elk, and c-Fos represents an important function and requires the translocation of ERK1/2 into the nucleus by active and passive processes involving the nuclear pore. These transcription factors participate in the immediate early gene response. The activity of the Ras-Raf-MEK-ERK cascade is increased in about one-third of all human cancers, and inhibition of components of this cascade by targeted inhibitors represents an important anti-tumor strategy. Thus far, however, only inhibition of mutant B-Raf (Val600Glu) has been found to be therapeutically efficacious.
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24
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Lee S, Bae YS. Monomeric and dimeric models of ERK2 in conjunction with studies on cellular localization, nuclear translocation, and in vitro analysis. Mol Cells 2012; 33:325-34. [PMID: 22450690 PMCID: PMC3887802 DOI: 10.1007/s10059-012-0023-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 02/21/2012] [Accepted: 02/27/2012] [Indexed: 11/24/2022] Open
Abstract
Extracellular signal-regulated protein kinase 2 (ERK2) plays many vital roles in cellular signal regulation. Phosphorylation of ERK2 leads to propagation and execution of various extracellular stimuli, which influence cellular responses to stress. The final response of the ERK2 signaling pathway is determined by localization and duration of active ERK2 at specific target cell compartments through protein-protein interactions of ERK2 with various cytoplasmic and nuclear substrates, scaffold proteins, and anchoring counterparts. In this respect, dimerization of phosphorylated ERK2 has been suggested to be a part of crucial regulating mechanism in various protein-protein interactions. After the report of putative dimeric structure of active ERK2 (Canagarajah et al., 1997), dimeric model was employed to explain many in vivo and in vitro experimental results. But more recently, many reports have been presented questioning the validity of dimer hypothesis of active ERK2. In this review, we summarize the various in vitro and in vivo studies concerning the Monomeric or the dimeric forms of ERK2 and the validity of the dimer hypothesis.
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Affiliation(s)
- Sunbae Lee
- Division of Life Sciences, Center for Cell Signal.ing Research, Ewha Womans University, Seoul 120-750, Korea.
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25
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Lee S, Warthaka M, Yan C, Kaoud TS, Ren P, Dalby KN. Examining docking interactions on ERK2 with modular peptide substrates. Biochemistry 2011; 50:9500-10. [PMID: 21955038 DOI: 10.1021/bi201103b] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
ERK2 primarily recognizes substrates through two recruitment sites, which lie outside the active site cleft of the kinase. These recruitment sites bind modular-docking sequences called docking sites and are potentially attractive sites for the development of non-ATP competitive inhibitors. The D-recruitment site (DRS) and the F-recruitment site (FRS) bind D-sites and F-sites, respectively. For example, peptides that target the FRS have been proposed to inhibit all ERK2 activity (Galanis, A., Yang, S. H., and Sharrocks, A. D. (2001) J. Biol. Chem. 276, 965-973); however, it has not been established whether this inhibition is steric or allosteric in origin. To facilitate inhibitor design and to examine potential coupling of recruitment sites to other ligand recognition sites within ERK2, energetic coupling within ERK2 was investigated using two new modular peptide substrates for ERK2. Modeling shows that one peptide (Sub-D) recognizes the DRS, while the other peptide (Sub-F) binds the FRS. A steady-state kinetic analysis reveals little evidence of thermodynamic linkage between the peptide substrate and ATP. Both peptides are phosphorylated through a random-order sequential mechanism with a k(cat)/K(m) comparable to Ets-1, a bona fide ERK2 substrate. Occupancy of the FRS with a peptide containing a modular docking sequence has no effect on the intrinsic ability of ERK2 to phosphorylate Sub-D. Occupancy of the DRS with a peptide containing a modular docking sequence has a slight effect (1.3 ± 0.1-fold increase in k(cat)) on the intrinsic ability of ERK2 to phosphorylate Sub-F. These data suggest that while docking interactions at the DRS and the FRS are energetically uncoupled, the DRS can exhibit weak communication to the active site. In addition, they suggest that peptides bound to the FRS inhibit the phosphorylation of protein substrates through a steric mechanism. The modeling and kinetic data suggest that the recruitment of ERK2 to cellular locations via its DRS may facilitate the formation of F-site selective ERK2 signaling complexes, while recruitment via the FRS will likely inhibit ERK2 through a steric mechanism of inhibition. Such recruitment may serve as an additional level of ERK2 regulation.
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Affiliation(s)
- Sunbae Lee
- Division of Medicinal Chemistry, University of Texas at Austin, Texas 78712, United States
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26
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Hollenhorst PC, McIntosh LP, Graves BJ. Genomic and biochemical insights into the specificity of ETS transcription factors. Annu Rev Biochem 2011; 80:437-71. [PMID: 21548782 DOI: 10.1146/annurev.biochem.79.081507.103945] [Citation(s) in RCA: 373] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
ETS proteins are a group of evolutionarily related, DNA-binding transcriptional factors. These proteins direct gene expression in diverse normal and disease states by binding to specific promoters and enhancers and facilitating assembly of other components of the transcriptional machinery. The highly conserved DNA-binding ETS domain defines the family and is responsible for specific recognition of a common sequence motif, 5'-GGA(A/T)-3'. Attaining specificity for biological regulation in such a family is thus a conundrum. We present the current knowledge of routes to functional diversity and DNA binding specificity, including divergent properties of the conserved ETS and PNT domains, the involvement of flanking structured and unstructured regions appended to these dynamic domains, posttranslational modifications, and protein partnerships with other DNA-binding proteins and coregulators. The review emphasizes recent advances from biochemical and biophysical approaches, as well as insights from genomic studies that detect ETS-factor occupancy in living cells.
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Affiliation(s)
- Peter C Hollenhorst
- Medical Sciences, Indiana University School of Medicine, Bloomington, Indiana 47405, USA.
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27
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Abramczyk O, Tavares CDJ, Devkota AK, Ryazanov AG, Turk BE, Riggs AF, Ozpolat B, Dalby KN. Purification and characterization of tagless recombinant human elongation factor 2 kinase (eEF-2K) expressed in Escherichia coli. Protein Expr Purif 2011; 79:237-44. [PMID: 21605678 DOI: 10.1016/j.pep.2011.05.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Revised: 05/04/2011] [Accepted: 05/05/2011] [Indexed: 01/28/2023]
Abstract
The eukaryotic elongation factor 2 kinase (eEF-2K) modulates the rate of protein synthesis by impeding the elongation phase of translation by inactivating the eukaryotic elongation factor 2 (eEF-2) via phosphorylation. eEF-2K is known to be activated by calcium and calmodulin, whereas the mTOR and MAPK pathways are suggested to negatively regulate kinase activity. Despite its pivotal role in translation regulation and potential role in tumor survival, the structure, function, and regulation of eEF-2K have not been described in detail. This deficiency may result from the difficulty of obtaining the recombinant kinase in a form suitable for biochemical analysis. Here we report the purification and characterization of recombinant human eEF-2K expressed in the Escherichia coli strain Rosetta-gami 2(DE3). Successive chromatography steps utilizing Ni-NTA affinity, anion-exchange, and gel filtration columns accomplished purification. Cleavage of the thioredoxin-His(6)-tag from the N-terminus of the expressed kinase with TEV protease yielded 9 mg of recombinant (G-D-I)-eEF-2K per liter of culture. Light scattering shows that eEF-2K is a monomer of ∼85 kDa. In vitro kinetic analysis confirmed that recombinant human eEF-2K is able to phosphorylate wheat germ eEF-2 with kinetic parameters comparable to the mammalian enzyme.
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Affiliation(s)
- Olga Abramczyk
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas, Austin, TX 78712, USA
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Kaoud TS, Devkota AK, Harris R, Rana MS, Abramczyk O, Warthaka M, Lee S, Girvin ME, Riggs AF, Dalby KN. Activated ERK2 is a monomer in vitro with or without divalent cations and when complexed to the cytoplasmic scaffold PEA-15. Biochemistry 2011; 50:4568-78. [PMID: 21506533 DOI: 10.1021/bi200202y] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The extracellular signal-regulated protein kinase, ERK2, fully activated by phosphorylation and without a His(6) tag, shows little tendency to dimerize with or without either calcium or magnesium ions when analyzed by light scattering or analytical ultracentrifugation. Light scattering shows that ~90% of ERK2 is monomeric. Sedimentation equilibrium data (obtained at 4.8-11.2 μM ERK2) with or without magnesium (10 mM) are well described by an ideal one-component model with a fitted molar mass of 40180 ± 240 Da (without Mg(2+) ions) or 41290 ± 330 Da (with Mg(2+) ions). These values, close to the sequence-derived mass of 41711 Da, indicate that no significant dimerization of ERK2 occurs in solution. Analysis of sedimentation velocity data for a 15 μM solution of ERK2 with an enhanced van Holde-Weischet method determined the sedimentation coefficient (s) to be ~3.22 S for activated ERK2 with or without 10 mM MgCl(2). The frictional coefficient ratio (f/f(0)) of 1.28 calculated from the sedimentation velocity and equilibrium data is close to that expected for an ~42 kDa globular protein. The translational diffusion coefficient of ~8.3 × 10(-7) cm(2) s(-1) calculated from the experimentally determined molar mass and sedimentation coefficient agrees with the value determined by dynamic light scattering in the absence and presence of calcium or magnesium ions and a value determined by NMR spectrometry. ERK2 has been proposed to homodimerize and bind only to cytoplasmic but not nuclear proteins [Casar, B., et al. (2008) Mol. Cell 31, 708-721]. Our light scattering data show, however, that ERK2 forms a strong 1:1 complex of ~57 kDa with the cytoplasmic scaffold protein PEA-15. Thus, ERK2 binds PEA-15 as a monomer. Our data provide strong evidence that ERK2 is monomeric under physiological conditions. Analysis of the same ERK2 construct with the nonphysiological His(6) tag shows substantial dimerization under the same ionic conditions.
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Affiliation(s)
- Tamer S Kaoud
- Division of Medicinal Chemistry, University of Texas, Austin, TX 78712, USA.
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29
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Piserchio A, Warthaka M, Devkota AK, Kaoud TS, Lee S, Abramczyk O, Ren P, Dalby KN, Ghose R. Solution NMR insights into docking interactions involving inactive ERK2. Biochemistry 2011; 50:3660-72. [PMID: 21449613 DOI: 10.1021/bi2000559] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The mitogen-activated protein (MAP) kinase ERK2 contains recruitment sites that engage canonical and noncanonical motifs found in a variety of upstream kinases, regulating phosphatases and downstream targets. Interactions involving two of these sites, the D-recruitment site (DRS) and the F-recruitment site (FRS), have been shown to play a key role in signal transduction by ERK/MAP kinases. The dynamic nature of these recruitment events makes NMR uniquely suited to provide significant insight into these interactions. While NMR studies of kinases in general have been greatly hindered by their large size and complex dynamic behavior leading to the suboptimal performance of standard methodologies, we have overcome these difficulties for inactive full-length ERK2 and obtained an acceptable level of backbone resonance assignments. This allowed a detailed investigation of the structural perturbations that accompany interactions involving both canonical and noncanonical recruitment events. No crystallographic information exists for the latter. We found that the chemical shift perturbations in inactive ERK2, indicative of structural changes in the presence of canonical and noncanonical motifs, are not restricted to the recruitment sites but also involve the linker that connects the N- and C-lobes and, in most cases, a gatekeeper residue that is thought to exert allosteric control over catalytic activity. We also found that, even though the canonical motifs interact with the DRS utilizing both charge-charge and hydrophobic interactions, the noncanonical interactions primarily involve the latter. These results demonstrate the feasibility of solution NMR techniques for a comprehensive analysis of docking interactions in a full-length ERK/MAP kinase.
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Affiliation(s)
- Andrea Piserchio
- Department of Chemistry, The City College of New York, New York, New York 10031, USA
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30
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Lee S, Warthaka M, Yan C, Kaoud TS, Piserchio A, Ghose R, Ren P, Dalby KN. A model of a MAPK•substrate complex in an active conformation: a computational and experimental approach. PLoS One 2011; 6:e18594. [PMID: 21494553 PMCID: PMC3073974 DOI: 10.1371/journal.pone.0018594] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 03/04/2011] [Indexed: 01/24/2023] Open
Abstract
The mechanisms by which MAP kinases recognize and phosphorylate substrates are not completely understood. Efforts to understand the mechanisms have been compromised by the lack of MAPK-substrate structures. While MAPK-substrate docking is well established as a viable mechanism for bringing MAPKs and substrates into close proximity the molecular details of how such docking promotes phosphorylation is an unresolved issue. In the present study computer modeling approaches, with restraints derived from experimentally known interactions, were used to predict how the N-terminus of Ets-1 associates with ERK2. Interestingly, the N-terminus does not contain a consensus-docking site ((R/K)2-3-X2-6-ΦA-X-ΦB, where Φ is aliphatic hydrophobic) for ERK2. The modeling predicts that the N-terminus of Ets-1 makes important contributions to the stabilization of the complex, but remains largely disordered. The computer-generated model was used to guide mutagenesis experiments, which support the notion that Leu-11 and possibly Ile-13 and Ile-14 of Ets-1 1-138 (Ets) make contributions through binding to the hydrophobic groove of the ERK2 D-recruiting site (DRS). Based on the modeling, a consensus-docking site was introduced through the introduction of an arginine at residue 7, to give the consensus 7RK-X2-ΦA-X-ΦB13. This results in a 2-fold increase in kcat/Km for the phosphorylation of Ets by ERK2. Similarly, the substitution of the N-terminus for two different consensus docking sites derived from Elk-1 and MKK1 also improves kcat/Km by two-fold compared to Ets. Disruption of the N-terminal docking through deletion of residues 1-23 of Ets results in a 14-fold decrease in kcat/Km, with little apparent change in kcat. A peptide that binds to the DRS of ERK2 affects Km, but not kcat. Our kinetic analysis suggests that the unstructured N-terminus provides 10-fold uniform stabilization of the ground state ERK2•Ets•MgATP complex and intermediates of the enzymatic reaction.
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Affiliation(s)
- Sunbae Lee
- Division of Medicinal Chemistry, University of Texas at Austin, Austin, Texas, United States of America
| | - Mangalika Warthaka
- Division of Medicinal Chemistry, University of Texas at Austin, Austin, Texas, United States of America
| | - Chunli Yan
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, United States of America
| | - Tamer S. Kaoud
- Division of Medicinal Chemistry, University of Texas at Austin, Austin, Texas, United States of America
- Graduate Program in Pharmacy, University of Texas at Austin, Austin, Texas, United States of America
| | - Andrea Piserchio
- Department of Chemistry, The City College of New York, New York, New York, United States of America
| | - Ranajeet Ghose
- Department of Chemistry, The City College of New York, New York, New York, United States of America
- The Graduate Center of The City University of New York, New York, New York, United States of America
| | - Pengyu Ren
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, United States of America
- Graduate Program in Biomedical Engineering, University of Texas at Austin, Austin, Texas, United States of America
- * E-mail: (KND); (PR)
| | - Kevin N. Dalby
- Division of Medicinal Chemistry, University of Texas at Austin, Austin, Texas, United States of America
- Graduate Program in Pharmacy, University of Texas at Austin, Austin, Texas, United States of America
- Graduate Program in Biomedical Engineering, University of Texas at Austin, Austin, Texas, United States of America
- Graduate Program in Biochemistry, University of Texas at Austin, Austin, Texas, United States of America
- * E-mail: (KND); (PR)
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31
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Callaway K, Waas WF, Rainey MA, Ren P, Dalby KN. Phosphorylation of the transcription factor Ets-1 by ERK2: rapid dissociation of ADP and phospho-Ets-1. Biochemistry 2010; 49:3619-30. [PMID: 20361728 DOI: 10.1021/bi100199q] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
ERK2, a major effector of the BRAF oncogene, is a promiscuous protein kinase that has a strong preference for phosphorylating substrates on Ser-Pro or Thr-Pro motifs. As part of a program to understand the fundamental basis for ERK2 substrate recognition and catalysis, we have studied the mechanism by which ERK2 phosphorylates the transcription factor Ets-1 at Thr-38. A feature of the mechanism in the forward direction is a partially rate-limiting product release step (koff = 59 +/- 6 s(-1)), which is significant because to approach maximum efficiency substrates for ERK2 may evolve to ensure that ADP dissociation is rate-limiting. To improve our understanding of the mechanism of product release, the binding of the products to ERK2 was assessed and the reaction was examined in the reverse direction. These studies demonstrated that phospho-Ets-1 (p-Ets) binds >20-fold more tightly to ERK2 than ADP (Kd = 7.3 and 165 microM, respectively) and revealed that the products exhibit little interaction energetically while bound to ERK2 and that they can dissociate ERK2 in a random order. The overall equilibrium for the reaction in solution (Keq = 250 M(-1)) was found to be similar to that with the substrate bound to the enzyme (Kint = 525 M(-1)). To determine what limits koff, several pre-steady-state experiments were performed. A catalytic trapping approach furnished a rate constant (k-ADPa) of 61 +/- 12 s(-1) for the dissociation of ADP from the abortive ternary complex, ERK2.Ets.ADP. To examine p-Ets dissociation, the binding of a fluorescent derivative (p-Ets-F), which binds ERK2 with an affinity similar to that of p-Ets, was examined by stopped-flow kinetics. Using this approach, p-Ets-F was found to bind through a single-step mechanism, with the following parameters: k-p-Ets-F = 121 +/- 3.8 s(-1), and kp-Ets-F = (9.4 +/- 0.3) X 10(6) M(-1) s(-1). Similar results were found in the presence of a saturating ADP concentration. These data suggest that koff may be limited by the dissociation of both products and are consistent with the notion that Ets-1 has evolved to be an efficient substrate for ERK2, where ADP release is, at least, partially rate-limiting. A molecular mechanics model of the complex formed between ERK2 and residues 28-138 of Ets-1 provides insight into the role of substrate docking interactions.
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Affiliation(s)
- Kari Callaway
- Division of Medicinal Chemistry, University of Texas, Austin, Texas 78712, USA
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32
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X-ray structures of NS1 effector domain mutants. Arch Biochem Biophys 2009; 494:198-204. [PMID: 19995550 DOI: 10.1016/j.abb.2009.12.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Revised: 12/01/2009] [Accepted: 12/04/2009] [Indexed: 11/21/2022]
Abstract
The influenza A virus nonstructural protein NS1 is a multifunctional dimeric protein that acts as a potent inhibitor of the host cellular antiviral state. The C-terminal effector domain of NS1 binds host proteins, including CPSF30, and is a target for the development of new antiviral drugs. Here we present crystallographic structures of two mutant effector domains, W187Y and W187A, of influenza A/Udorn/72 virus. Unlike wild-type, the mutants behave exclusively as monomers in solution based on gel filtration data and light scattering. The W187Y mutant is able to bind CPSF30 with a binding affinity close to the wild-type protein; that is, it retains a receptor site for aromatic ligands nearly identical to the wild-type. Therefore, this monomeric mutant protein could serve as a drug target for a high throughput inhibitor screening assays, since its binding pocket is unoccupied in solution and potentially more accessible to small molecule ligands.
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33
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Arredondo SA, Chen TF, Riggs AF, Gilbert HF, Georgiou G. Role of dimerization in the catalytic properties of the Escherichia coli disulfide isomerase DsbC. J Biol Chem 2009; 284:23972-9. [PMID: 19581640 DOI: 10.1074/jbc.m109.010199] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The bacterial protein-disulfide isomerase DsbC is a homodimeric V-shaped enzyme that consists of a dimerization domain, two alpha-helical linkers, and two opposing thioredoxin fold catalytic domains. The functional significance of the two catalytic domains of DsbC is not well understood yet. We have engineered heterodimer-like DsbC derivatives covalently linked via (Gly(3)-Ser) flexible linkers. We either inactivated one of the catalytic sites (CGYC), or entirely removed one of the catalytic domains while maintaining the putative binding area intact. Variants having a single active catalytic site display significant levels of isomerase activity. Furthermore, mDsbC[H45D]-dim[D53H], a DsbC variant lacking an entire catalytic domain but with an intact dimerization domain, also showed isomerase activity, albeit at lower levels. In addition, the absence of the catalytic domain allowed this protein to catalyze in vivo oxidation. Our results reveal that two catalytic domains in DsbC are not essential for disulfide bond isomerization and that a determining feature in isomerization is the availability of a substrate binding domain.
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Affiliation(s)
- Silvia A Arredondo
- Department of Chemical Engineering, School of Biological Sciences, University of Texas, Austin, Texas 78712, USA
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34
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Milkiewicz M, Uchida C, Gee E, Fudalewski T, Haas TL. Shear stress-induced Ets-1 modulates protease inhibitor expression in microvascular endothelial cells. J Cell Physiol 2008; 217:502-10. [PMID: 18636553 DOI: 10.1002/jcp.21526] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Elevated shear stress within the skeletal muscle microvasculature is implicated in the induction of a longitudinal splitting form of angiogenesis, which is characterized by the lack of basement membrane breakage. We investigated whether the transcriptional regulator, Ets-1, is responsive to changes in hemodynamic forces and if so, whether Ets-1 controls microvascular endothelial cell integrity by inducing the expression of inhibitors of matrix degrading proteases. Rats were treated with prazosin for 2, 4, and 7 days to increase in microvascular shear stress in hindlimb skeletal muscles. In complimentary in vitro experiments, rat microvascular skeletal muscle endothelial cells were exposed to laminar shear stress (15 dyne/cm(2)) for 0.5, 2, and 24 h. TaqMan PCR analysis of laser microdissected capillaries isolated from EDL muscles demonstrated transient (after 2 days) induction of Ets-1 gene expression. In cultured cells, a transient up-regulation of Ets-1 mRNA was observed after 2 h shear stimulation, accompanied by increased phosphorylation of Ets-1 and enhanced Ets-1 DNA binding activity. This response was modulated by ERK1/2 and p38 MAP kinases, but was not dependent on NOS or COX-2 activity. PAI-1, TIMP-1 and TIMP-3 mRNA were elevated significantly in prazosin treated EDL, and in response to shear stimulation in vitro. In cultured endothelial cells, Ets-1 RNA interference abolished the shear-induced increases in Ets-1, PAI-1, TIMP-1, and TIMP-3 mRNA expression. These results suggest that enhanced laminar shear stress may act to preserve the integrity of microvascular walls in part through Ets-1-dependent induction of protease inhibitors.
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35
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Wooderchak WL, Zang T, Zhou ZS, Acuña M, Tahara SM, Hevel JM. Substrate Profiling of PRMT1 Reveals Amino Acid Sequences That Extend Beyond the “RGG” Paradigm. Biochemistry 2008; 47:9456-66. [DOI: 10.1021/bi800984s] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Whitney L. Wooderchak
- Chemistry and Biochemistry Department, Utah State University,
0300 Old Main Hill, Logan, Utah 84322, The Barnett Institute of Chemical
and Biological Analysis and Department of Chemistry and Chemical Biology,
Northeastern University, 360 Huntington Avenue, Boston, Massachusetts
02115-5000, Molecular Microbiology and Neurology, University of Southern
California School of Medicine, 2011 Zonal Avenue, Los Angeles, California
90033, and Affiliate of the Center for Integrated Biosystems, Utah
State University
| | - Tianzhu Zang
- Chemistry and Biochemistry Department, Utah State University,
0300 Old Main Hill, Logan, Utah 84322, The Barnett Institute of Chemical
and Biological Analysis and Department of Chemistry and Chemical Biology,
Northeastern University, 360 Huntington Avenue, Boston, Massachusetts
02115-5000, Molecular Microbiology and Neurology, University of Southern
California School of Medicine, 2011 Zonal Avenue, Los Angeles, California
90033, and Affiliate of the Center for Integrated Biosystems, Utah
State University
| | - Zhaohui Sunny Zhou
- Chemistry and Biochemistry Department, Utah State University,
0300 Old Main Hill, Logan, Utah 84322, The Barnett Institute of Chemical
and Biological Analysis and Department of Chemistry and Chemical Biology,
Northeastern University, 360 Huntington Avenue, Boston, Massachusetts
02115-5000, Molecular Microbiology and Neurology, University of Southern
California School of Medicine, 2011 Zonal Avenue, Los Angeles, California
90033, and Affiliate of the Center for Integrated Biosystems, Utah
State University
| | - Marcela Acuña
- Chemistry and Biochemistry Department, Utah State University,
0300 Old Main Hill, Logan, Utah 84322, The Barnett Institute of Chemical
and Biological Analysis and Department of Chemistry and Chemical Biology,
Northeastern University, 360 Huntington Avenue, Boston, Massachusetts
02115-5000, Molecular Microbiology and Neurology, University of Southern
California School of Medicine, 2011 Zonal Avenue, Los Angeles, California
90033, and Affiliate of the Center for Integrated Biosystems, Utah
State University
| | - Stanley M. Tahara
- Chemistry and Biochemistry Department, Utah State University,
0300 Old Main Hill, Logan, Utah 84322, The Barnett Institute of Chemical
and Biological Analysis and Department of Chemistry and Chemical Biology,
Northeastern University, 360 Huntington Avenue, Boston, Massachusetts
02115-5000, Molecular Microbiology and Neurology, University of Southern
California School of Medicine, 2011 Zonal Avenue, Los Angeles, California
90033, and Affiliate of the Center for Integrated Biosystems, Utah
State University
| | - Joan M. Hevel
- Chemistry and Biochemistry Department, Utah State University,
0300 Old Main Hill, Logan, Utah 84322, The Barnett Institute of Chemical
and Biological Analysis and Department of Chemistry and Chemical Biology,
Northeastern University, 360 Huntington Avenue, Boston, Massachusetts
02115-5000, Molecular Microbiology and Neurology, University of Southern
California School of Medicine, 2011 Zonal Avenue, Los Angeles, California
90033, and Affiliate of the Center for Integrated Biosystems, Utah
State University
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36
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Sheridan DL, Kong Y, Parker SA, Dalby KN, Turk BE. Substrate discrimination among mitogen-activated protein kinases through distinct docking sequence motifs. J Biol Chem 2008; 283:19511-20. [PMID: 18482985 DOI: 10.1074/jbc.m801074200] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitogen-activated protein kinases (MAPKs) mediate cellular responses to a wide variety of extracellular stimuli. MAPK signal transduction cascades are tightly regulated, and individual MAPKs display exquisite specificity in recognition of their target substrates. All MAPK family members share a common phosphorylation site motif, raising questions as to how substrate specificity is achieved. Here we describe a peptide library screen to identify sequence requirements of the DEF site (docking site for ERK FXF), a docking motif separate from the phosphorylation site. We show that MAPK isoforms recognize DEF sites with unique sequences and identify two key residues on the MAPK that largely dictate sequence specificity. Based on these observations and computational docking studies, we propose a revised model for MAPK interaction with substrates containing DEF sites. Variations in DEF site sequence requirements provide one possible mechanism for encoding complex target specificity among MAPK isoforms.
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Affiliation(s)
- Douglas L Sheridan
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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Abramczyk O, Rainey MA, Barnes R, Martin L, Dalby KN. Expanding the repertoire of an ERK2 recruitment site: cysteine footprinting identifies the D-recruitment site as a mediator of Ets-1 binding. Biochemistry 2007; 46:9174-86. [PMID: 17658891 PMCID: PMC2897722 DOI: 10.1021/bi7002058] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Many substrates of ERK2 contain a D-site, a sequence recognized by ERK2 that is used to promote catalysis. Despite lacking a canonical D-site, the substrate Ets-1 is displaced from ERK2 by peptides containing one. This suggests that Ets-1 may contain a novel or cryptic D-site. To investigate this possibility a protein footprinting strategy was developed to elucidate ERK2-ligand interactions. Using this approach, single cysteine reporters were placed in the D-recruitment site (DRS) of ERK2 and the resulting ERK2 proteins subjected to alkylation by iodoacetamide. The ability of residues 1-138 of Ets-1 to protect the cysteines from alkylation was determined. The pattern of protection observed is consistent with Ets-1 occupying a hydrophobic binding site within the DRS of ERK2. Significantly, a peptide derived from the D-site of Elk-1, which is known to bind the DRS, exhibits a similar pattern of cysteine protection. This analysis expands the repertoire of the DRS on ERK2 and suggests that other targeting sequences remain to be identified. Furthermore, cysteine-footprinting is presented as a useful way to interrogate protein-ligand interactions at the resolution of a single amino acid.
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Affiliation(s)
- Olga Abramczyk
- Division of Medicinal Chemistry, University of Texas at Austin, Texas 78712
| | - Mark A. Rainey
- Graduate Program in Molecular Biology, University of Texas at Austin, Texas 78712
| | - Richard Barnes
- Graduate Program in Biochemistry, University of Texas at Austin, Texas 78712
| | - Lance Martin
- Department of Biochemistry, Stanford University, Stanford, California 94305
| | - Kevin N. Dalby
- Division of Medicinal Chemistry, University of Texas at Austin, Texas 78712
- Graduate Program in Molecular Biology, University of Texas at Austin, Texas 78712
- Graduate Program in Biochemistry, University of Texas at Austin, Texas 78712
- Corresponding author. Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, TX 78712. Tel: 512-4719267. Fax: 512-2322606.
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38
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Waas WF, Dalby KN. The expression and purification of the N-terminal activation domain of the transcription factor c-Myc: a model substrate for exploring ERK2 docking interactions. Protein Expr Purif 2007; 53:80-6. [PMID: 17251036 DOI: 10.1016/j.pep.2006.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 12/05/2006] [Accepted: 12/07/2006] [Indexed: 10/23/2022]
Abstract
ERK2 is a mitogen-activated protein kinase (MAPK) that plays pivotal roles in cell signal transduction, where it mediates effects on proliferation and differentiation by growth factors and hormones. An important substrate of ERK2 is the transcription factor c-Myc, which mediates cell cycle progression. The phosphorylation of Ser-62 on c-Myc by ERK2 is thought to contribute to the increased stability of c-Myc during the cell cycle and is thus a critical cellular event. However, the mode of c-Myc recognition by ERK2 is not understood. Early studies by Gupta and Davis concluded that ERK2 specificity determinants are located in residues 1-100 of c-Myc, its activation domain. To pursue both structural and kinetic studies a rapid, but efficient purification method, for the production of the activation domain of c-Myc from an Escherichia coli source, was developed. We chose the minimal number of high-resolution steps to maximize both yield and efficiency without sacrificing purity. Thus, GST-(c-MycDelta2-99)-His(6) was expressed in E. coli, and purified using glutathione-agarose affinity chromatography. Cleavage of the GST fusion protein by thrombin and subsequent purification by nickel-agarose affinity chromatography yielded 8 mg of purified (c-MycDelta2-99)-His(6) from one liter of LB culture. Rigorous characterization demonstrated that under standard assay conditions (c-MycDelta2-99)-His(6) is phosphorylated by ERK2 with the following Michaelis parameters: k(cat)=10.4s(-1), K(M)(c-Myc)=57.4 microM. In summary, a rapid procedure is outlined for the preparation of (c-MycDelta2-99)-His(6) that will be useful for mechanistic and biophysical studies of ERK2.
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Affiliation(s)
- William F Waas
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, TX 78712, USA
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39
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Brahma A, Dalby KN. Regulation of protein phosphorylation within the MKK1-ERK2 complex by MP1 and the MP1*P14 heterodimer. Arch Biochem Biophys 2007; 460:85-91. [PMID: 17254543 PMCID: PMC2853909 DOI: 10.1016/j.abb.2006.11.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2006] [Revised: 11/29/2006] [Accepted: 11/29/2006] [Indexed: 11/30/2022]
Abstract
MEK partner 1 (MP1) and P14 are small proteins that modulate the Raf-MKK1/2-ERK1/2 pathway. To examine the biochemical basis for their function a fluorescent form of MP1 was prepared by labeling Cys-74 with fluorescein. Using this protein it was shown that MP1 binds unactivated ERK1, ERK2 and a constitutively active form of MKK1 (MKK1G7B) with dissociation constants of 9.7+/-1.6, 3.3+/-0.6 and 2.2+/-0.5 microM, respectively. MP1 inhibits the ability of activated ERK2 to phosphorylate the transcription factor Ets-1. Both MP1 and the MP1*P14 complex inhibit the ability of activated ERK2 to phosphorylate MKK1G7B, thus impeding feedback inhibition. In contrast, MP1 and the P14*MP1 complex enhance the ability of MKK1G7B to phosphorylate ERK2, when ERK2 is present at a low concentration, but not when it is present at a high concentration. Thus, MP1 and the MP1*P14 complex have the potential to differentially modulate activating and inhibiting signals in the Raf-MKK1/2-ERK1/2 pathway.
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Affiliation(s)
- Amrita Brahma
- Division of Medicinal Chemistry, University of Texas, Austin, TX 78712-0252
| | - Kevin N. Dalby
- Division of Medicinal Chemistry, University of Texas, Austin, TX 78712-0252
- Graduate Program in Biochemistry, University of Texas, Austin, TX 78712-0252
- Graduate Program in Molecular Biology, University of Texas, Austin, TX 78712-0252
- Center for Molecular and Cellular Toxicology, University of Texas, Austin, TX 78712-0252
- Corresponding author: Kevin N. Dalby, Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, 78712, USA. Tel. 512-4719267. Fax. 512-2322606, E mail:
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