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Brownfield BA, Richardson BC, Halaby SL, Fromme JC. Sec7 regulatory domains scaffold autoinhibited and active conformations. Proc Natl Acad Sci U S A 2024; 121:e2318615121. [PMID: 38416685 PMCID: PMC10927569 DOI: 10.1073/pnas.2318615121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 01/16/2024] [Indexed: 03/01/2024] Open
Abstract
The late stages of Golgi maturation involve a series of sequential trafficking events in which cargo-laden vesicles are produced and targeted to multiple distinct subcellular destinations. Each of these vesicle biogenesis events requires activation of an Arf GTPase by the Sec7/BIG guanine nucleotide exchange factor (GEF). Sec7 localization and activity is regulated by autoinhibition, positive feedback, and interaction with other GTPases. Although these mechanisms have been characterized biochemically, we lack a clear picture of how GEF localization and activity is modulated by these signals. Here, we report the cryogenic electron microscopy structure of full-length Sec7 in its autoinhibited form, revealing the architecture of its multiple regulatory domains. We use functional experiments to determine the basis for autoinhibition and use structural predictions to produce a model for an active conformation of the GEF that is supported empirically. This study therefore elucidates the conformational transition that Sec7 undergoes to become active on the organelle membrane surface.
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Affiliation(s)
- Bryce A. Brownfield
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
| | - Brian C. Richardson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
| | - Steve L. Halaby
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
| | - J. Christopher Fromme
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY14853
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Li G, Dang J, Pan J, Liu J, Peng T, Chen G, Wang R, Hu S, Li X, Hu X. Genome-Wide Analysis of the DC1 Domain Protein Gene Family in Tomatoes under Abiotic Stress. Int J Mol Sci 2023; 24:16994. [PMID: 38069320 PMCID: PMC10707348 DOI: 10.3390/ijms242316994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 11/27/2023] [Accepted: 11/28/2023] [Indexed: 12/18/2023] Open
Abstract
DC1 (Divergent C1) domain proteins are a new class of proteins that have been discovered in recent years, which play an important role in plant growth, development, and stress response. In order to better study the distribution and function of DC1 domain proteins in tomatoes, a genome-wide identification was conducted. It was found that there are twenty-one DC1 domain protein genes distributed on nine chromosomes of tomatoes, named SlCHP1-21. Phylogenetic analysis shows that twenty-one SlCHP genes are divided into six subfamilies. Most of the SlCHP genes in tomatoes have no or very short introns. All SlCHP proteins, with the exception of SlCHP8 and SlCHP17, contain variable amounts of C1 domain. Analysis of the SlCHP gene promoter sequence revealed multiple cis-elements responsive to plant stress. qRT-CR analysis showed that most members of SlCHP gene expressed in the roots. The SlCHP11, 13, 16, 17, and SlCHP20 genes showed specific responses to high temperature, low temperature, salt, and drought stress. In addition, the subcellular localization and interaction proteins of SlCHP were analyzed and predicted. Together, these results provides a theoretical basis for further exploration of the function and mechanism of the SlCHP gene in tomatoes.
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Affiliation(s)
- Guobin Li
- College of Horticulture, Northwest A&F University, Yangling 712100, China; (G.L.); (J.D.); (J.P.); (J.L.); (T.P.); (G.C.); (R.W.); (S.H.); (X.L.)
- Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Yangling 712100, China
- Shaanxi Protected Agriculture Research Centre, Yangling 712100, China
| | - Jiao Dang
- College of Horticulture, Northwest A&F University, Yangling 712100, China; (G.L.); (J.D.); (J.P.); (J.L.); (T.P.); (G.C.); (R.W.); (S.H.); (X.L.)
- Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Yangling 712100, China
- Shaanxi Protected Agriculture Research Centre, Yangling 712100, China
| | - Jiaqi Pan
- College of Horticulture, Northwest A&F University, Yangling 712100, China; (G.L.); (J.D.); (J.P.); (J.L.); (T.P.); (G.C.); (R.W.); (S.H.); (X.L.)
- Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Yangling 712100, China
- Shaanxi Protected Agriculture Research Centre, Yangling 712100, China
| | - Jingyi Liu
- College of Horticulture, Northwest A&F University, Yangling 712100, China; (G.L.); (J.D.); (J.P.); (J.L.); (T.P.); (G.C.); (R.W.); (S.H.); (X.L.)
| | - Tieli Peng
- College of Horticulture, Northwest A&F University, Yangling 712100, China; (G.L.); (J.D.); (J.P.); (J.L.); (T.P.); (G.C.); (R.W.); (S.H.); (X.L.)
- Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Yangling 712100, China
- Shaanxi Protected Agriculture Research Centre, Yangling 712100, China
| | - Guo Chen
- College of Horticulture, Northwest A&F University, Yangling 712100, China; (G.L.); (J.D.); (J.P.); (J.L.); (T.P.); (G.C.); (R.W.); (S.H.); (X.L.)
| | - Rongqun Wang
- College of Horticulture, Northwest A&F University, Yangling 712100, China; (G.L.); (J.D.); (J.P.); (J.L.); (T.P.); (G.C.); (R.W.); (S.H.); (X.L.)
| | - Songshen Hu
- College of Horticulture, Northwest A&F University, Yangling 712100, China; (G.L.); (J.D.); (J.P.); (J.L.); (T.P.); (G.C.); (R.W.); (S.H.); (X.L.)
- Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Yangling 712100, China
- Shaanxi Protected Agriculture Research Centre, Yangling 712100, China
| | - Xiaojing Li
- College of Horticulture, Northwest A&F University, Yangling 712100, China; (G.L.); (J.D.); (J.P.); (J.L.); (T.P.); (G.C.); (R.W.); (S.H.); (X.L.)
- Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Yangling 712100, China
- Shaanxi Protected Agriculture Research Centre, Yangling 712100, China
| | - Xiaohui Hu
- College of Horticulture, Northwest A&F University, Yangling 712100, China; (G.L.); (J.D.); (J.P.); (J.L.); (T.P.); (G.C.); (R.W.); (S.H.); (X.L.)
- Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Yangling 712100, China
- Shaanxi Protected Agriculture Research Centre, Yangling 712100, China
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Brownfield BA, Richardson BC, Halaby SL, Fromme JC. Sec7 regulatory domains scaffold autoinhibited and active conformations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.22.568272. [PMID: 38045260 PMCID: PMC10690275 DOI: 10.1101/2023.11.22.568272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
The late stages of Golgi maturation involve a series of sequential trafficking events in which cargo-laden vesicles are produced and targeted to multiple distinct subcellular destinations. Each of these vesicle biogenesis events requires activation of an Arf GTPase by the Sec7/BIG guanine nucleotide exchange factor (GEF). Sec7 localization and activity is regulated by autoinhibition, positive feedback, and interaction with other GTPases. Although these mechanisms have been characterized biochemically, we lack a clear picture of how GEF localization and activity is modulated by these signals. Here we report the cryoEM structure of full-length Sec7 in its autoinhibited form, revealing the architecture of its multiple regulatory domains. We use functional experiments to determine the basis for autoinhibition and use structural predictions to produce a model for an active conformation of the GEF that is supported empirically. This study therefore elucidates the conformational transition that Sec7 undergoes to become active on the organelle membrane surface.
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Affiliation(s)
- Bryce A. Brownfield
- Department of Molecular Biology & Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14850 USA
| | - Brian C. Richardson
- Department of Molecular Biology & Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14850 USA
- Current address: The Hormel Institute, University of Minnesota, Austin MN 55912
| | - Steve L. Halaby
- Department of Molecular Biology & Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14850 USA
- Current address: Abbvie Inc., Irvine, CA 92612
| | - J. Christopher Fromme
- Department of Molecular Biology & Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14850 USA
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You Y, Mathukumali K, Das J. Comparison of the ligand binding site of C1 domains: a molecular dynamics simulation study of the C1 domain-phorbol 13-acetate-membrane system. J Biomol Struct Dyn 2023; 41:11796-11809. [PMID: 36602779 PMCID: PMC10319914 DOI: 10.1080/07391102.2022.2163699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 12/23/2022] [Indexed: 01/06/2023]
Abstract
C1 domains are lipid-binding structural units of about 50 residues. Typical C1 domains associate with the plasma membrane and bind to diacylglycerol/phorbol ester during the activation of the proteins containing these domains. Although the overall structure of the C1 domains are similar, there are differences in their primary sequence and in the orientation of the ligand/lipid binding residues. To gain structural insights into the ligand/lipid binding, we performed molecular docking of phorbol 13-acetate into the C1 domain and 1.0 μs molecular dynamics simulation on the C1 domain-ligand-lipid ternary system for PKCθ C1A, PKCδ C1B, PKCβII C1B, PKCθ C1B, Munc13-1 C1, and βII-Chimaerin C1. We divided these C1 domains into three types based on the orientations of Gln-27 and Trp/Tyr-22. In type 1, Trp/Tyr-22 is outside and Gln-27 is inside the ligand binding pocket. In type 2, both Trp/Tyr-22 and Gln-27 are outside the ligand binding pocket, and in type 3, Trp/Tyr-22 is inside and Gln-27 is outside the pocket. The type 1 C1 domains showed higher ligand binding and higher membrane binding with a shorter distance between the C1 domain and the membrane than the type 2 and type 3. For ligand binding, Pro-11 plays a major role in the type 1 and 2, and Gly-23 in the type 1 and type 3 C1 domains. This study elucidates the role of Gln-27, Trp-22, Pro-11 and Gly-23 in ligand/lipid binding in typical C1 domains and bears significance in developing selective modulators of C1 domain-containing proteins.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Youngki You
- Department of Pharmacological & Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, U.S.A
| | - Kavya Mathukumali
- Department of Pharmacological & Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, U.S.A
| | - Joydip Das
- Department of Pharmacological & Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, U.S.A
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Cooke M, Kazanietz MG. Overarching roles of diacylglycerol signaling in cancer development and antitumor immunity. Sci Signal 2022; 15:eabo0264. [PMID: 35412850 DOI: 10.1126/scisignal.abo0264] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Diacylglycerol (DAG) is a lipid second messenger that is generated in response to extracellular stimuli and channels intracellular signals that affect mammalian cell proliferation, survival, and motility. DAG exerts a myriad of biological functions through protein kinase C (PKC) and other effectors, such as protein kinase D (PKD) isozymes and small GTPase-regulating proteins (such as RasGRPs). Imbalances in the fine-tuned homeostasis between DAG generation by phospholipase C (PLC) enzymes and termination by DAG kinases (DGKs), as well as dysregulation in the activity or abundance of DAG effectors, have been widely associated with tumor initiation, progression, and metastasis. DAG is also a key orchestrator of T cell function and thus plays a major role in tumor immunosurveillance. In addition, DAG pathways shape the tumor ecosystem by arbitrating the complex, dynamic interaction between cancer cells and the immune landscape, hence representing powerful modifiers of immune checkpoint and adoptive T cell-directed immunotherapy. Exploiting the wide spectrum of DAG signals from an integrated perspective could underscore meaningful advances in targeted cancer therapy.
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Affiliation(s)
- Mariana Cooke
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.,Department of Medicine, Einstein Medical Center Philadelphia, Philadelphia, PA 19141, USA
| | - Marcelo G Kazanietz
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Fixing the GAP: the role of RhoGAPs in cancer. Eur J Cell Biol 2022; 101:151209. [DOI: 10.1016/j.ejcb.2022.151209] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 01/29/2022] [Accepted: 02/08/2022] [Indexed: 12/12/2022] Open
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Lee CF, Carley RE, Butler CA, Morrison AR. Rac GTPase Signaling in Immune-Mediated Mechanisms of Atherosclerosis. Cells 2021; 10:2808. [PMID: 34831028 PMCID: PMC8616135 DOI: 10.3390/cells10112808] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 10/15/2021] [Accepted: 10/17/2021] [Indexed: 11/17/2022] Open
Abstract
Coronary artery disease caused by atherosclerosis is a major cause of morbidity and mortality around the world. Data from preclinical and clinical studies support the belief that atherosclerosis is an inflammatory disease that is mediated by innate and adaptive immune signaling mechanisms. This review sought to highlight the role of Rac-mediated inflammatory signaling in the mechanisms driving atherosclerotic calcification. In addition, current clinical treatment strategies that are related to targeting hypercholesterolemia as a critical risk factor for atherosclerotic vascular disease are addressed in relation to the effects on Rac immune signaling and the implications for the future of targeting immune responses in the treatment of calcific atherosclerosis.
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Affiliation(s)
- Cadence F. Lee
- Ocean State Research Institute, Inc., Providence VA Medical Center, Research (151), 830 Chalkstone Avenue, Providence, RI 02908, USA; (C.F.L.); (R.E.C.); (C.A.B.)
- Alpert Medical School, Brown University, Providence, RI 02912, USA
| | - Rachel E. Carley
- Ocean State Research Institute, Inc., Providence VA Medical Center, Research (151), 830 Chalkstone Avenue, Providence, RI 02908, USA; (C.F.L.); (R.E.C.); (C.A.B.)
- Alpert Medical School, Brown University, Providence, RI 02912, USA
| | - Celia A. Butler
- Ocean State Research Institute, Inc., Providence VA Medical Center, Research (151), 830 Chalkstone Avenue, Providence, RI 02908, USA; (C.F.L.); (R.E.C.); (C.A.B.)
- Alpert Medical School, Brown University, Providence, RI 02912, USA
| | - Alan R. Morrison
- Ocean State Research Institute, Inc., Providence VA Medical Center, Research (151), 830 Chalkstone Avenue, Providence, RI 02908, USA; (C.F.L.); (R.E.C.); (C.A.B.)
- Alpert Medical School, Brown University, Providence, RI 02912, USA
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SOX10-regulated promoter use defines isoform-specific gene expression in Schwann cells. BMC Genomics 2020; 21:549. [PMID: 32770939 PMCID: PMC7430845 DOI: 10.1186/s12864-020-06963-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 07/29/2020] [Indexed: 01/12/2023] Open
Abstract
Background Multicellular organisms adopt various strategies to tailor gene expression to cellular contexts including the employment of multiple promoters (and the associated transcription start sites (TSSs)) at a single locus that encodes distinct gene isoforms. Schwann cells—the myelinating cells of the peripheral nervous system (PNS)—exhibit a specialized gene expression profile directed by the transcription factor SOX10, which is essential for PNS myelination. SOX10 regulates promoter elements associated with unique TSSs and gene isoforms at several target loci, implicating SOX10-mediated, isoform-specific gene expression in Schwann cell function. Here, we report on genome-wide efforts to identify SOX10-regulated promoters and TSSs in Schwann cells to prioritize genes and isoforms for further study. Results We performed global TSS analyses and mined previously reported ChIP-seq datasets to assess the activity of SOX10-bound promoters in three models: (i) an adult mammalian nerve; (ii) differentiating primary Schwann cells, and (iii) cultured Schwann cells with ablated SOX10 function. We explored specific characteristics of SOX10-dependent TSSs, which provides confidence in defining them as SOX10 targets. Finally, we performed functional studies to validate our findings at four previously unreported SOX10 target loci: ARPC1A, CHN2, DDR1, and GAS7. These findings suggest roles for the associated SOX10-regulated gene products in PNS myelination. Conclusions In sum, we provide comprehensive computational and functional assessments of SOX10-regulated TSS use in Schwann cells. The data presented in this study will stimulate functional studies on the specific mRNA and protein isoforms that SOX10 regulates, which will improve our understanding of myelination in the peripheral nerve.
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Humphries BA, Wang Z, Yang C. MicroRNA Regulation of the Small Rho GTPase Regulators-Complexities and Opportunities in Targeting Cancer Metastasis. Cancers (Basel) 2020; 12:E1092. [PMID: 32353968 PMCID: PMC7281527 DOI: 10.3390/cancers12051092] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/24/2020] [Accepted: 04/25/2020] [Indexed: 02/07/2023] Open
Abstract
The small Rho GTPases regulate important cellular processes that affect cancer metastasis, such as cell survival and proliferation, actin dynamics, adhesion, migration, invasion and transcriptional activation. The Rho GTPases function as molecular switches cycling between an active GTP-bound and inactive guanosine diphosphate (GDP)-bound conformation. It is known that Rho GTPase activities are mainly regulated by guanine nucleotide exchange factors (RhoGEFs), GTPase-activating proteins (RhoGAPs), GDP dissociation inhibitors (RhoGDIs) and guanine nucleotide exchange modifiers (GEMs). These Rho GTPase regulators are often dysregulated in cancer; however, the underlying mechanisms are not well understood. MicroRNAs (miRNAs), a large family of small non-coding RNAs that negatively regulate protein-coding gene expression, have been shown to play important roles in cancer metastasis. Recent studies showed that miRNAs are capable of directly targeting RhoGAPs, RhoGEFs, and RhoGDIs, and regulate the activities of Rho GTPases. This not only provides new evidence for the critical role of miRNA dysregulation in cancer metastasis, it also reveals novel mechanisms for Rho GTPase regulation. This review summarizes recent exciting findings showing that miRNAs play important roles in regulating Rho GTPase regulators (RhoGEFs, RhoGAPs, RhoGDIs), thus affecting Rho GTPase activities and cancer metastasis. The potential opportunities and challenges for targeting miRNAs and Rho GTPase regulators in treating cancer metastasis are also discussed. A comprehensive list of the currently validated miRNA-targeting of small Rho GTPase regulators is presented as a reference resource.
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Affiliation(s)
- Brock A. Humphries
- Center for Molecular Imaging, Department of Radiology, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Zhishan Wang
- Department of Toxicology and Cancer Biology, College of Medicine, University of Kentucky, 1095 V A Drive, Lexington, KY 40536, USA;
| | - Chengfeng Yang
- Department of Toxicology and Cancer Biology, College of Medicine, University of Kentucky, 1095 V A Drive, Lexington, KY 40536, USA;
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Molecular Regulation of the RhoGAP GRAF3 and Its Capacity to Limit Blood Pressure In Vivo. Cells 2020; 9:cells9041042. [PMID: 32331391 PMCID: PMC7226614 DOI: 10.3390/cells9041042] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 04/20/2020] [Indexed: 12/26/2022] Open
Abstract
Anti-hypertensive therapies are usually prescribed empirically and are often ineffective. Given the prevalence and deleterious outcomes of hypertension (HTN), improved strategies are needed. We reported that the Rho-GAP GRAF3 is selectively expressed in smooth muscle cells (SMC) and controls blood pressure (BP) by limiting the RhoA-dependent contractility of resistance arterioles. Importantly, genetic variants at the GRAF3 locus controls BP in patients. The goal of this study was to validate GRAF3 as a druggable candidate for future anti-HTN therapies. Importantly, using a novel mouse model, we found that modest induction of GRAF3 in SMC significantly decreased basal and vasoconstrictor-induced BP. Moreover, we found that GRAF3 protein toggles between inactive and active states by processes controlled by the mechano-sensing kinase, focal adhesion kinase (FAK). Using resonance energy transfer methods, we showed that agonist-induced FAK-dependent phosphorylation at Y376GRAF3 reverses an auto-inhibitory interaction between the GAP and BAR-PH domains. Y376 is located in a linker between the PH and GAP domains and is invariant in GRAF3 homologues and a phosphomimetic E376GRAF3 variant exhibited elevated GAP activity. Collectively, these data provide strong support for the future identification of allosteric activators of GRAF3 for targeted anti-hypertensive therapies.
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Müller PM, Rademacher J, Bagshaw RD, Wortmann C, Barth C, van Unen J, Alp KM, Giudice G, Eccles RL, Heinrich LE, Pascual-Vargas P, Sanchez-Castro M, Brandenburg L, Mbamalu G, Tucholska M, Spatt L, Czajkowski MT, Welke RW, Zhang S, Nguyen V, Rrustemi T, Trnka P, Freitag K, Larsen B, Popp O, Mertins P, Gingras AC, Roth FP, Colwill K, Bakal C, Pertz O, Pawson T, Petsalaki E, Rocks O. Systems analysis of RhoGEF and RhoGAP regulatory proteins reveals spatially organized RAC1 signalling from integrin adhesions. Nat Cell Biol 2020; 22:498-511. [PMID: 32203420 DOI: 10.1038/s41556-020-0488-x] [Citation(s) in RCA: 120] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 02/18/2020] [Indexed: 02/07/2023]
Abstract
Rho GTPases are central regulators of the cytoskeleton and, in humans, are controlled by 145 multidomain guanine nucleotide exchange factors (RhoGEFs) and GTPase-activating proteins (RhoGAPs). How Rho signalling patterns are established in dynamic cell spaces to control cellular morphogenesis is unclear. Through a family-wide characterization of substrate specificities, interactomes and localization, we reveal at the systems level how RhoGEFs and RhoGAPs contextualize and spatiotemporally control Rho signalling. These proteins are widely autoinhibited to allow local regulation, form complexes to jointly coordinate their networks and provide positional information for signalling. RhoGAPs are more promiscuous than RhoGEFs to confine Rho activity gradients. Our resource enabled us to uncover a multi-RhoGEF complex downstream of G-protein-coupled receptors controlling CDC42-RHOA crosstalk. Moreover, we show that integrin adhesions spatially segregate GEFs and GAPs to shape RAC1 activity zones in response to mechanical cues. This mechanism controls the protrusion and contraction dynamics fundamental to cell motility. Our systems analysis of Rho regulators is key to revealing emergent organization principles of Rho signalling.
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Affiliation(s)
- Paul M Müller
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | | | - Richard D Bagshaw
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | | | - Carolin Barth
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | - Jakobus van Unen
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Keziban M Alp
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | - Girolamo Giudice
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, UK
| | | | - Louise E Heinrich
- Institute of Cancer Research, Chester Beatty Laboratories, London, UK
| | | | - Marta Sanchez-Castro
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | | | - Geraldine Mbamalu
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | - Monika Tucholska
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | - Lisa Spatt
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | - Maciej T Czajkowski
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | | | - Sunqu Zhang
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | - Vivian Nguyen
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | | | - Philipp Trnka
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | - Kiara Freitag
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
| | - Brett Larsen
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | - Oliver Popp
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Philipp Mertins
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
- Berlin Institute of Health (BIH), Berlin, Germany
| | - Anne-Claude Gingras
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Frederick P Roth
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
- Donnelly Centre and Departments of Molecular Genetics and Computer Science, University of Toronto, Toronto, Ontario, Canada
- Canadian Institute for Advanced Research, Toronto, Ontario, Canada
| | - Karen Colwill
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
| | - Chris Bakal
- Institute of Cancer Research, Chester Beatty Laboratories, London, UK
| | - Olivier Pertz
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Tony Pawson
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Evangelia Petsalaki
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada.
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, UK.
| | - Oliver Rocks
- Max-Delbrück-Center for Molecular Medicine, Berlin, Germany.
- Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Ontario, Canada.
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13
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Casado-Medrano V, Barrio-Real L, Gutiérrez-Miranda L, González-Sarmiento R, Velasco EA, Kazanietz MG, Caloca MJ. Identification of a truncated β1-chimaerin variant that inactivates nuclear Rac1. J Biol Chem 2019; 295:1300-1314. [PMID: 31871052 DOI: 10.1074/jbc.ra119.008688] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 12/14/2019] [Indexed: 12/11/2022] Open
Abstract
β1-chimaerin belongs to the chimaerin family of GTPase-activating proteins (GAPs) and is encoded by the CHN2 gene, which also encodes the β2- and β3-chimaerin isoforms. All chimaerin isoforms have a C1 domain that binds diacylglycerol as well as tumor-promoting phorbol esters and a catalytic GAP domain that inactivates the small GTPase Rac. Nuclear Rac has emerged as a key regulator of various cell functions, including cell division, and has a pathological role by promoting tumorigenesis and metastasis. However, how nuclear Rac is regulated has not been fully addressed. Here, using several approaches, including siRNA-mediated gene silencing, confocal microscopy, and subcellular fractionation, we identified a nuclear variant of β1-chimaerin, β1-Δ7p-chimaerin, that participates in the regulation of nuclear Rac1. We show that β1-Δ7p-chimaerin is a truncated variant generated by alternative splicing at a cryptic splice site in exon 7. We found that, unlike other chimaerin isoforms, β1-Δ7p-chimaerin lacks a functional C1 domain and is not regulated by diacylglycerol. We found that β1-Δ7p-chimaerin localizes to the nucleus via a nuclear localization signal in its N terminus. We also identified a key nuclear export signal in β1-chimaerin that is absent in β1-Δ7p-chimaerin, causing nuclear retention of this truncated variant. Functionally analyses revealed that β1-Δ7p-chimaerin inactivates nuclear Rac and negatively regulates the cell cycle. Our results provide important insights into the diversity of chimaerin Rac-GAP regulation and function and highlight a potential mechanism of nuclear Rac inactivation that may play significant roles in pathologies such as cancer.
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Affiliation(s)
- Victoria Casado-Medrano
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
| | - Laura Barrio-Real
- Molecular Medicine Unit and Institute of Molecular and Cellular Biology of Cancer, Biomedical Research Institute of Salamanca, University of Salamanca, 37007 Salamanca, Spain
| | - Laura Gutiérrez-Miranda
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
| | - Rogelio González-Sarmiento
- Molecular Medicine Unit and Institute of Molecular and Cellular Biology of Cancer, Biomedical Research Institute of Salamanca, University of Salamanca, 37007 Salamanca, Spain
| | - Eladio A Velasco
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
| | - Marcelo G Kazanietz
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - María J Caloca
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Valladolid, 47003 Valladolid, Spain
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14
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Blanco FA, Czikora A, Kedei N, You Y, Mitchell GA, Pany S, Ghosh A, Blumberg PM, Das J. Munc13 Is a Molecular Target of Bryostatin 1. Biochemistry 2019; 58:3016-3030. [PMID: 31243993 PMCID: PMC6620733 DOI: 10.1021/acs.biochem.9b00427] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
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Bryostatin
1 is a natural macrolide shown to improve neuronal connections and
enhance memory in mice. Its mechanism of action is largely attributed
to the modulation of novel and conventional protein kinase Cs (PKCs)
by binding to their regulatory C1 domains. Munc13-1 is a C1 domain-containing
protein that shares common endogenous and exogenous activators with
novel and conventional PKC subtypes. Given the essential role of Munc13-1
in the priming of synaptic vesicles and neuronal transmission overall,
we explored the potential interaction between bryostatin 1 and Munc13-1.
Our results indicate that in vitro bryostatin 1 binds
to both the isolated C1 domain of Munc13-1 (Ki = 8.07 ± 0.90 nM) and the full-length Munc13-1 protein
(Ki = 0.45 ± 0.04 nM). Furthermore,
confocal microscopy and immunoblot analysis demonstrated that in intact
HT22 cells bryostatin 1 mimics the actions of phorbol esters, a previously
established class of Munc13-1 activators, and induces plasma membrane
translocation of Munc13-1, a hallmark of its activation. Consistently,
bryostatin 1 had no effect on the Munc13-1H567K construct
that is insensitive to phorbol esters. Effects of bryostatin 1 on
the other Munc13 family members, ubMunc13-2 and bMunc13-2, resembled
those of Munc13-1 for translocation. Lastly, we observed an increased
level of expression of Munc13-1 following a 24 h incubation with bryostatin
1 in both HT22 and primary mouse hippocampal cells. This study characterizes
Munc13-1 as a molecular target of bryostatin 1. Considering the crucial
role of Munc13-1 in neuronal function, these findings provide strong
support for the potential role of Munc13s in the actions of bryostatin
1.
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Affiliation(s)
- Francisco A Blanco
- Department of Pharmacological & Pharmaceutical Sciences, College of Pharmacy , University of Houston , Houston , Texas 77204 , United States
| | - Agnes Czikora
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Noemi Kedei
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Youngki You
- Department of Pharmacological & Pharmaceutical Sciences, College of Pharmacy , University of Houston , Houston , Texas 77204 , United States
| | - Gary A Mitchell
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Satyabrata Pany
- Department of Pharmacological & Pharmaceutical Sciences, College of Pharmacy , University of Houston , Houston , Texas 77204 , United States
| | - Anamitra Ghosh
- Department of Pharmacological & Pharmaceutical Sciences, College of Pharmacy , University of Houston , Houston , Texas 77204 , United States
| | - Peter M Blumberg
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute , National Institutes of Health , Bethesda , Maryland 20892 , United States
| | - Joydip Das
- Department of Pharmacological & Pharmaceutical Sciences, College of Pharmacy , University of Houston , Houston , Texas 77204 , United States
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15
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Gallo Castro D, Martin SG. Differential GAP requirement for Cdc42-GTP polarization during proliferation and sexual reproduction. J Cell Biol 2018; 217:4215-4229. [PMID: 30279276 PMCID: PMC6279383 DOI: 10.1083/jcb.201806016] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 09/06/2018] [Accepted: 09/21/2018] [Indexed: 12/13/2022] Open
Abstract
The formation of a local zone of Cdc42 GTPase activity, which governs cell polarization in many cell types, requires not only local activation but also switch-off mechanisms. In this study, we identify Rga3, a paralog of Rga4, as a novel Cdc42 GTPase-activating protein (GAP) in the fission yeast Schizosaccharomyces pombe Contrary to Rga4, Rga3 localizes with Cdc42-GTP to sites of polarity. Rga3 is dispensable for cell polarization during mitotic growth, but it limits the lifetime of unstable Cdc42-GTP patches that underlie cell pairing during sexual reproduction, masking a partly compensatory patch-wandering motion. In consequence, cells lacking rga3 hyperpolarize and lose out in mating competition. Rga3 synergizes with the Cdc42 GAPs Rga4 and Rga6 to restrict Cdc42-GTP zone sizes during mitotic growth. Surprisingly, triple-mutant cells, which are almost fully round, retain pheromone-dependent dynamic polarization of Cdc42-GTP, extend a polarized projection, and mate. Thus, the requirement for Cdc42-GTP hydrolysis by GAPs is distinct during polarization by intrinsic or extrinsic cues.
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Affiliation(s)
- Daniela Gallo Castro
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Sophie G Martin
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
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16
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The RacGAP β-Chimaerin is essential for cerebellar granule cell migration. Sci Rep 2018; 8:680. [PMID: 29330522 PMCID: PMC5766509 DOI: 10.1038/s41598-017-19116-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 12/21/2017] [Indexed: 11/08/2022] Open
Abstract
During mammalian cerebellar development, postnatal granule cell progenitors proliferate in the outer part of the External Granule Layer (EGL). Postmitotic granule progenitors migrate tangentially in the inner EGL before switching to migrate radially inward, past the Purkinje cell layer, to achieve their final position in the mature Granule Cell Layer (GCL). Here, we show that the RacGAP β-chimaerin is expressed by a small population of late-born, premigratory granule cells. β-chimaerin deficiency causes a subset of granule cells to become arrested in the EGL, where they differentiate and form ectopic neuronal clusters. These clusters of granule cells are able to recruit aberrantly projecting mossy fibers. Collectively, these data suggest a role for β-chimaerin as an intracellular mediator of Cerebellar Granule Cell radial migration.
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17
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Czikora A, Pany S, You Y, Saini AS, Lewin NE, Mitchell GA, Abramovitz A, Kedei N, Blumberg PM, Das J. Structural determinants of phorbol ester binding activity of the C1a and C1b domains of protein kinase C theta. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1046-1056. [PMID: 29317197 DOI: 10.1016/j.bbamem.2018.01.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 12/06/2017] [Accepted: 01/04/2018] [Indexed: 12/31/2022]
Abstract
The PKC isozymes represent the most prominent family of signaling proteins mediating response to the ubiquitous second messenger diacylglycerol. Among them, PKCθ is critically involved in T-cell activation. Whereas all the other conventional and novel PKC isoforms have twin C1 domains with potent binding activity for phorbol esters, in PKCθ only the C1b domain possesses potent binding activity, with little or no activity reported for the C1a domain. In order to better understand the structural basis accounting for the very weak ligand binding of the PKCθ C1a domain, we assessed the effect on ligand binding of twelve amino acid residues which differed between the C1a and C1b domains of PKCθ. Mutation of Pro9 of the C1a domain of PKCθ to the corresponding Lys9 found in C1b restored in vitro binding activity for [3H]phorbol 12,13-dibutyrate to 3.6 nM, whereas none of the other residues had substantial effect. Interestingly, the converse mutation in the C1b domain of Lys9 to Pro9 only diminished binding affinity to 11.7 nM, compared to 254 nM in the unmutated C1a. In confocal experiments, deletion of the C1b domain from full length PKCθ diminished, whereas deletion of the C1a domain enhanced 5-fold (at 100 nM PMA) the translocation to the plasma membrane. We conclude that the Pro168 residue in the C1a domain of full length PKCθ plays a critical role in the ligand and membrane binding, while exchanging the residue (Lys240) at the same position in C1b domain of full length PKCθ only modestly reduced the membrane interaction.
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Affiliation(s)
- Agnes Czikora
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, United States
| | - Satyabrata Pany
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, United States
| | - Youngki You
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, United States
| | - Amandeep S Saini
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, United States
| | - Nancy E Lewin
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, United States
| | - Gary A Mitchell
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, United States
| | - Adelle Abramovitz
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, United States
| | - Noemi Kedei
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, United States
| | - Peter M Blumberg
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, United States.
| | - Joydip Das
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, United States.
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18
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Das J, Kedei N, Kelsey JS, You Y, Pany S, Mitchell GA, Lewin NE, Blumberg PM. Critical Role of Trp-588 of Presynaptic Munc13-1 for Ligand Binding and Membrane Translocation. Biochemistry 2018; 57:732-741. [PMID: 29244485 DOI: 10.1021/acs.biochem.7b00764] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Munc13-1 is a presynaptic active-zone protein essential for neurotransmitter release and presynaptic plasticity in the brain. This multidomain scaffold protein contains a C1 domain that binds to the activator diacylglycerol/phorbol ester. Although the C1 domain bears close structural homology with the C1 domains of protein kinase C (PKC), the tryptophan residue at position 22 (588 in the full-length Munc13-1) occludes the activator binding pocket, which is not the case for PKC. To elucidate the role of this tryptophan, we generated W22A, W22K, W22D, W22Y, and W22F substitutions in the full-length Munc13-1, expressed the GFP-tagged constructs in Neuro-2a cells, and measured their membrane translocation in response to phorbol ester treatment by imaging of the live cells using confocal microscopy. The extent of membrane translocation followed the order, wild-type > W22K > W22F > W22Y > W22A > W22D. The phorbol ester binding affinity of the wild-type Munc13-1C1 domain and its mutants was phosphatidylserine (PS)-dependent following the order, wild-type > W22K > W22A ≫ W22D in both 20% and 100% PS. Phorbol ester affinity was higher for Munc13-1 than the C1 domain. While Munc13-1 translocated to the plasma membrane, the C1 domain translocated to internal membranes in response to phorbol ester. Molecular dynamics (80 ns) studies reveal that Trp-22 is relatively less flexible than the homologous Trp-22 of PKCδ and PKCθ. Results are discussed in terms of the overall negative charge state of the Munc13-1C1 domain and its possible interaction with the PS-rich plasma membrane. This study shows that Trp-588 is an important structural element for ligand binding and membrane translocation in Munc13-1.
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Affiliation(s)
- Joydip Das
- Department of Pharmacological & Pharmaceutical Sciences, College of Pharmacy, University of Houston , Houston, Texas 77204, United States
| | - Noemi Kedei
- Center for Cancer Research, National Cancer Institute , Bethesda, Maryland 20892, United States
| | - Jessica S Kelsey
- Center for Cancer Research, National Cancer Institute , Bethesda, Maryland 20892, United States
| | - Youngki You
- Department of Pharmacological & Pharmaceutical Sciences, College of Pharmacy, University of Houston , Houston, Texas 77204, United States
| | - Satyabrata Pany
- Department of Pharmacological & Pharmaceutical Sciences, College of Pharmacy, University of Houston , Houston, Texas 77204, United States
| | - Gary A Mitchell
- Center for Cancer Research, National Cancer Institute , Bethesda, Maryland 20892, United States
| | - Nancy E Lewin
- Center for Cancer Research, National Cancer Institute , Bethesda, Maryland 20892, United States
| | - Peter M Blumberg
- Center for Cancer Research, National Cancer Institute , Bethesda, Maryland 20892, United States
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19
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Kelsey JS, Géczy T, Kaler CJ, Blumberg PM. The C1 domain of Vav3, a novel potential therapeutic target. Cell Signal 2017; 40:133-142. [PMID: 28927664 PMCID: PMC5651187 DOI: 10.1016/j.cellsig.2017.09.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 08/22/2017] [Accepted: 09/14/2017] [Indexed: 12/12/2022]
Abstract
Vav1/2/3 comprise a protein family with guanyl nucleotide exchange activity for Rho and Rac as well as with motifs conferring adapter activity. Biologically, Vav1 plays a critical role in hematologic cell signaling, whereas Vav2/3 have a wider tissue distribution, but all 3 Vav proteins are implicated in cancer development. A structural feature of Vav1/2/3 is the presence of an atypical C1 domain, which possesses close structural homology to the typical C1 domains of protein kinase C but which fails to bind the second messenger diacylglycerol or the potent analogs, the phorbol esters. Previously, we have shown that five residues in the Vav1 C1 domain are responsible for its lack of phorbol ester binding. Here, we show that the lack of phorbol ester binding of Vav3 has a similar basis. We then explore the consequences of phorbol ester binding to a modified Vav3 in which the C1 domain has been altered to allow phorbol ester binding. We find both disruption of the guanyl nucleotide exchange activity of the modified Vav 3 as well as a shift in localization to the membrane upon phorbol ester treatment. This change in localization is associated with altered interactions with other signaling proteins. The studies provide a first step in assessing the potential for the design of custom C1 domain targeted molecules selective for the atypical C1 domains of Vav family proteins.
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Affiliation(s)
- Jessica S Kelsey
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Tamás Géczy
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Christopher J Kaler
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Peter M Blumberg
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
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20
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Sporny M, Guez-Haddad J, Kreusch A, Shakartzi S, Neznansky A, Cross A, Isupov MN, Qualmann B, Kessels MM, Opatowsky Y. Structural History of Human SRGAP2 Proteins. Mol Biol Evol 2017; 34:1463-1478. [PMID: 28333212 PMCID: PMC5435084 DOI: 10.1093/molbev/msx094] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In the development of the human brain, human-specific genes are considered to play key roles, conferring its unique advantages and vulnerabilities. At the time of Homo lineage divergence from Australopithecus, SRGAP2C gradually emerged through a process of serial duplications and mutagenesis from ancestral SRGAP2A (3.4–2.4 Ma). Remarkably, ectopic expression of SRGAP2C endows cultured mouse brain cells, with human-like characteristics, specifically, increased dendritic spine length and density. To understand the molecular mechanisms underlying this change in neuronal morphology, we determined the structure of SRGAP2A and studied the interplay between SRGAP2A and SRGAP2C. We found that: 1) SRGAP2A homo-dimerizes through a large interface that includes an F-BAR domain, a newly identified F-BAR extension (Fx), and RhoGAP-SH3 domains. 2) SRGAP2A has an unusual inverse geometry, enabling associations with lamellipodia and dendritic spine heads in vivo, and scaffolding of membrane protrusions in cell culture. 3) As a result of the initial partial duplication event (∼3.4 Ma), SRGAP2C carries a defective Fx-domain that severely compromises its solubility and membrane-scaffolding ability. Consistently, SRGAP2A:SRAGP2C hetero-dimers form, but are insoluble, inhibiting SRGAP2A activity. 4) Inactivation of SRGAP2A is sensitive to the level of hetero-dimerization with SRGAP2C. 5) The primal form of SRGAP2C (P-SRGAP2C, existing between ∼3.4 and 2.4 Ma) is less effective in hetero-dimerizing with SRGAP2A than the modern SRGAP2C, which carries several substitutions (from ∼2.4 Ma). Thus, the genetic mutagenesis phase contributed to modulation of SRGAP2A’s inhibition of neuronal expansion, by introducing and improving the formation of inactive SRGAP2A:SRGAP2C hetero-dimers, indicating a stepwise involvement of SRGAP2C in human evolutionary history.
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Affiliation(s)
- Michael Sporny
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Julia Guez-Haddad
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Annett Kreusch
- Institute for Biochemistry I, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Sivan Shakartzi
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Avi Neznansky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Alice Cross
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Michail N Isupov
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom
| | - Britta Qualmann
- Institute for Biochemistry I, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Michael M Kessels
- Institute for Biochemistry I, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - Yarden Opatowsky
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
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21
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Chilton JK, Guthrie S. Axons get ahead: Insights into axon guidance and congenital cranial dysinnervation disorders. Dev Neurobiol 2017; 77:861-875. [DOI: 10.1002/dneu.22477] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 12/07/2016] [Accepted: 12/07/2016] [Indexed: 11/12/2022]
Affiliation(s)
- John K. Chilton
- Wellcome Wolfson Centre for Medical Research; University of Exeter Medical School, Wellcome-Wolfson Centre for Medical Research; Exeter EX2 5DW United Kingdom
| | - Sarah Guthrie
- School of Life Sciences; University of Sussex; Falmer Brighton, BN1 9QG
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22
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Huang GH, Sun ZL, Li HJ, Feng DF. Rho GTPase-activating proteins: Regulators of Rho GTPase activity in neuronal development and CNS diseases. Mol Cell Neurosci 2017; 80:18-31. [PMID: 28163190 DOI: 10.1016/j.mcn.2017.01.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 01/06/2017] [Accepted: 01/29/2017] [Indexed: 12/22/2022] Open
Abstract
The Rho family of small GTPases was considered as molecular switches in regulating multiple cellular events, including cytoskeleton reorganization. The Rho GTPase-activating proteins (RhoGAPs) are one of the major families of Rho GTPase regulators. RhoGAPs were initially considered negative mediators of Rho signaling pathways via their GAP domain. Recent studies have demonstrated that RhoGAPs also regulate numerous aspects of neuronal development and are related to various neurodegenerative diseases in GAP-dependent and GAP-independent manners. Moreover, RhoGAPs are regulated through various mechanisms, such as phosphorylation. To date, approximately 70 RhoGAPs have been identified; however, only a small portion has been thoroughly investigated. Thus, the characterization of important RhoGAPs in the central nervous system is crucial to understand their spatiotemporal role during different stages of neuronal development. In this review, we summarize the current knowledge of RhoGAPs in the brain with an emphasis on their molecular function, regulation mechanism and disease implications in the central nervous system.
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Affiliation(s)
- Guo-Hui Huang
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Zhao-Liang Sun
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Hong-Jiang Li
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China
| | - Dong-Fu Feng
- Department of Neurosurgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China; Institute of Traumatic Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai 201900, China.
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23
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Amin E, Jaiswal M, Derewenda U, Reis K, Nouri K, Koessmeier KT, Aspenström P, Somlyo AV, Dvorsky R, Ahmadian MR. Deciphering the Molecular and Functional Basis of RHOGAP Family Proteins: A SYSTEMATIC APPROACH TOWARD SELECTIVE INACTIVATION OF RHO FAMILY PROTEINS. J Biol Chem 2016; 291:20353-71. [PMID: 27481945 PMCID: PMC5034035 DOI: 10.1074/jbc.m116.736967] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 07/15/2016] [Indexed: 12/30/2022] Open
Abstract
RHO GTPase-activating proteins (RHOGAPs) are one of the major classes of regulators of the RHO-related protein family that are crucial in many cellular processes, motility, contractility, growth, differentiation, and development. Using database searches, we extracted 66 distinct human RHOGAPs, from which 57 have a common catalytic domain capable of terminating RHO protein signaling by stimulating the slow intrinsic GTP hydrolysis (GTPase) reaction. The specificity of the majority of the members of RHOGAP family is largely uncharacterized. Here, we comprehensively investigated the sequence-structure-function relationship between RHOGAPs and RHO proteins by combining our in vitro data with in silico data. The activity of 14 representatives of the RHOGAP family toward 12 RHO family proteins was determined in real time. We identified and structurally verified hot spots in the interface between RHOGAPs and RHO proteins as critical determinants for binding and catalysis. We have found that the RHOGAP domain itself is nonselective and in some cases rather inefficient under cell-free conditions. Thus, we propose that other domains of RHOGAPs confer substrate specificity and fine-tune their catalytic efficiency in cells.
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Affiliation(s)
- Ehsan Amin
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Mamta Jaiswal
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Urszula Derewenda
- the Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, and
| | - Katarina Reis
- the Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Kazem Nouri
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Katja T Koessmeier
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, 40225 Düsseldorf, Germany
| | - Pontus Aspenström
- the Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Avril V Somlyo
- the Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, and
| | - Radovan Dvorsky
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, 40225 Düsseldorf, Germany,
| | - Mohammad R Ahmadian
- From the Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, 40225 Düsseldorf, Germany,
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24
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Mishra AK, Lambright DG. Invited review: Small GTPases and their GAPs. Biopolymers 2016; 105:431-48. [PMID: 26972107 PMCID: PMC5439442 DOI: 10.1002/bip.22833] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 02/16/2016] [Accepted: 03/10/2016] [Indexed: 12/11/2022]
Abstract
Widespread utilization of small GTPases as major regulatory hubs in many different biological systems derives from a conserved conformational switch mechanism that facilitates cycling between GTP-bound active and GDP-bound inactive states under control of guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs), which accelerate slow intrinsic rates of activation by nucleotide exchange and deactivation by GTP hydrolysis, respectively. Here we review developments leading to current understanding of intrinsic and GAP catalyzed GTP hydrolytic reactions in small GTPases from structural, molecular and chemical mechanistic perspectives. Despite the apparent simplicity of the GTPase cycle, the structural bases underlying the hallmark hydrolytic reaction and catalytic acceleration by GAPs are considerably more diverse than originally anticipated. Even the most fundamental aspects of the reaction mechanism have been challenging to decipher. Through a combination of experimental and in silico approaches, the outlines of a consensus view have begun to emerge for the best studied paradigms. Nevertheless, recent observations indicate that there is still much to be learned. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 431-448, 2016.
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Affiliation(s)
- Ashwini K Mishra
- Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605
| | - David G Lambright
- Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605
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25
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Bao H, Li F, Wang C, Wang N, Jiang Y, Tang Y, Wu J, Shi Y. Structural Basis for the Specific Recognition of RhoA by the Dual GTPase-activating Protein ARAP3. J Biol Chem 2016; 291:16709-19. [PMID: 27311713 DOI: 10.1074/jbc.m116.736140] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Indexed: 02/04/2023] Open
Abstract
ARAP3 (Arf-GAP with Rho-GAP domain, ANK repeat, and PH domain-containing protein 3) is unique for its dual specificity GAPs (GTPase-activating protein) activity for Arf6 (ADP-ribosylation factor 6) and RhoA (Ras homolog gene family member A) regulated by phosphatidylinositol 3,4,5-trisphosphate and a small GTPase Rap1-GTP and is involved in regulation of cell shape and adhesion. However, the molecular interface between the ARAP3-RhoGAP domain and RhoA is unknown, as is the substrates specificity of the RhoGAP domain. In this study, we solved the crystal structure of RhoA in complex with the RhoGAP domain of ARAP3. The structure of the complex presented a clear interface between the RhoGAP domain and RhoA. By analyzing the crystal structure and in combination with in vitro GTPase activity assays and isothermal titration calorimetry experiments, we identified the crucial residues affecting RhoGAP activity and substrates specificity among RhoA, Rac1 (Ras-related C3 botulinum toxin substrate 1), and Cdc42 (cell division control protein 42 homolog).
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Affiliation(s)
- Hongyu Bao
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Fudong Li
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Chongyuan Wang
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Na Wang
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Yiyang Jiang
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Yajun Tang
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Jihui Wu
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Yunyu Shi
- From the Hefei National Laboratory for Physical Science at Microscale, Collaborative Innovation Center of Chemistry for Life Sciences and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, China
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26
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Czikora A, Lundberg DJ, Abramovitz A, Lewin NE, Kedei N, Peach ML, Zhou X, Merritt RC, Craft EA, Braun DC, Blumberg PM. Structural Basis for the Failure of the C1 Domain of Ras Guanine Nucleotide Releasing Protein 2 (RasGRP2) to Bind Phorbol Ester with High Affinity. J Biol Chem 2016; 291:11133-47. [PMID: 27022025 PMCID: PMC4900263 DOI: 10.1074/jbc.m116.725333] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 03/28/2016] [Indexed: 11/06/2022] Open
Abstract
The C1 domain represents the recognition module for diacylglycerol and phorbol esters in protein kinase C, Ras guanine nucleotide releasing protein (RasGRP), and related proteins. RasGRP2 is exceptional in that its C1 domain has very weak binding affinity (Kd = 2890 ± 240 nm for [(3)H]phorbol 12,13-dibutyrate. We have identified four amino acid residues responsible for this lack of sensitivity. Replacing Asn(7), Ser(8), Ala(19), and Ile(21) with the corresponding residues from RasGRP1/3 (Thr(7), Tyr(8), Gly(19), and Leu(21), respectively) conferred potent binding affinity (Kd = 1.47 ± 0.03 nm) in vitro and membrane translocation in response to phorbol 12-myristate 13-acetate in LNCaP cells. Mutant C1 domains incorporating one to three of the four residues showed intermediate behavior with S8Y making the greatest contribution. Binding activity for diacylglycerol was restored in parallel. The requirement for anionic phospholipid for [(3)H]phorbol 12,13-dibutyrate binding was determined; it decreased in going from the single S8Y mutant to the quadruple mutant. The full-length RasGRP2 protein with the mutated C1 domains also showed strong phorbol ester binding, albeit modestly weaker than that of the C1 domain alone (Kd = 8.2 ± 1.1 nm for the full-length protein containing all four mutations), and displayed translocation in response to phorbol ester. RasGRP2 is a guanyl exchange factor for Rap1. Consistent with the ability of phorbol ester to induce translocation of the full-length RasGRP2 with the mutated C1 domain, phorbol ester enhanced the ability of the mutated RasGRP2 to activate Rap1. Modeling confirmed that the four mutations helped the binding cleft maintain a stable conformation.
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Affiliation(s)
- Agnes Czikora
- From the Laboratory of Cancer Biology and Genetics, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Daniel J Lundberg
- Department of Science, Technology, and Mathematics, Gallaudet University, Washington, D. C. 20002, and
| | - Adelle Abramovitz
- From the Laboratory of Cancer Biology and Genetics, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Nancy E Lewin
- From the Laboratory of Cancer Biology and Genetics, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Noemi Kedei
- From the Laboratory of Cancer Biology and Genetics, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Megan L Peach
- Basic Science Program, Leidos Biomedical Research, Inc., Chemical Biology Laboratory, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702
| | - Xiaoling Zhou
- From the Laboratory of Cancer Biology and Genetics, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892
| | - Raymond C Merritt
- Department of Science, Technology, and Mathematics, Gallaudet University, Washington, D. C. 20002, and
| | - Elizabeth A Craft
- Department of Science, Technology, and Mathematics, Gallaudet University, Washington, D. C. 20002, and
| | - Derek C Braun
- Department of Science, Technology, and Mathematics, Gallaudet University, Washington, D. C. 20002, and
| | - Peter M Blumberg
- From the Laboratory of Cancer Biology and Genetics, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892,
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27
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Developmental RacGAP α2-Chimaerin Signaling Is a Determinant of the Morphological Features of Dendritic Spines in Adulthood. J Neurosci 2016; 35:13728-44. [PMID: 26446225 DOI: 10.1523/jneurosci.0419-15.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Morphological characteristics of dendritic spines form the basis of cognitive ability. However, molecular mechanisms involved in fine-tuning of spine morphology during development are not fully understood. Moreover, it is unclear whether, and to what extent, these developmental mechanisms determine the normal adult spine morphological features. Here, we provide evidence that α2-isoform of Rac-specific GTPase-activating protein α-chimaerin (α2-chimaerin) is involved in spine morphological refinement during late postnatal period, and furthermore show that this developmental α2-chimaerin function affects adult spine morphologies. We used a series of mice with global and conditional knock-out of α-chimaerin isoforms (α1-chimaerin and α2-chimaerin). α2-Chimaerin disruption, but not α1-chimaerin disruption, in the mouse results in an increased size (and density) of spines in the hippocampus. In contrast, overexpression of α2-chimaerin in developing hippocampal neurons induces a decrease of spine size. Disruption of α2-chimaerin suppressed EphA-mediated spine morphogenesis in cultured developing hippocampal neurons. α2-Chimaerin disruption that begins during the juvenile stage results in an increased size of spines in the hippocampus. Meanwhile, spine morphologies are unaltered when α2-chimaerin is deleted only in adulthood. Consistent with these spine morphological results, disruption of α2-chimaerin beginning in the juvenile stage led to an increase in contextual fear learning in adulthood; whereas contextual learning was recently shown to be unaffected when α2-chimaerin was deleted only in adulthood. Together, these results suggest that α2-chimaerin signaling in developmental stages contributes to determination of the morphological features of adult spines and establishment of normal cognitive ability. SIGNIFICANCE STATEMENT Recent studies of neurodevelopmental disorders in humans and their animal models have led to an attractive hypothesis that spine morphogenesis during development forms the basis of adult cognition. In particular, the roles of Rac and its regulators, such as Rac-specific GTPase-activating proteins (RacGAPs) and Rac guanine nucleotide exchange factors, are a topic of focus in spine morphogenesis and cognitive ability. Using a series of mice with global and conditional knock-out (KO) of RacGAP α-chimaerin isoforms (α1-chimaerin and α2-chimaerin), we provide compelling evidence demonstrating that α2-chimaerin is involved in spine morphological refinement during late postnatal development and that this developmental α2-chimaerin function affects adult spine morphologies. Furthermore, our results clearly showed that α2-chimaerin signaling during late postnatal development contributes to normal cognitive ability in adult mice.
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28
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Breznau EB, Semack AC, Higashi T, Miller AL. MgcRacGAP restricts active RhoA at the cytokinetic furrow and both RhoA and Rac1 at cell-cell junctions in epithelial cells. Mol Biol Cell 2015; 26:2439-55. [PMID: 25947135 PMCID: PMC4571299 DOI: 10.1091/mbc.e14-11-1553] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 04/30/2015] [Indexed: 12/17/2022] Open
Abstract
MgcRacGAP's role in regulating the spatiotemporal dynamics of active RhoA and Rac1 in epithelial cells is investigated. MgcRacGAP's GAP activity down-regulates RhoA at the furrow and both RhoA and Rac1 at cell–cell junctions in dividing epithelial cells and is required for successful cytokinesis and cell–cell junction structure. MgcRacGAP's ability to regulate adherens junctions is dependent on GAP activity and signaling via the RhoA pathway. Localized activation of Rho GTPases is essential for multiple cellular functions, including cytokinesis and formation and maintenance of cell–cell junctions. Although MgcRacGAP (Mgc) is required for spatially confined RhoA-GTP at the equatorial cortex of dividing cells, both the target specificity of Mgc's GAP activity and the involvement of phosphorylation of Mgc at Ser-386 are controversial. In addition, Mgc's function at cell–cell junctions remains unclear. Here, using gastrula-stage Xenopus laevis embryos as a model system, we examine Mgc's role in regulating localized RhoA-GTP and Rac1-GTP in the intact vertebrate epithelium. We show that Mgc's GAP activity spatially restricts accumulation of both RhoA-GTP and Rac1-GTP in epithelial cells—RhoA at the cleavage furrow and RhoA and Rac1 at cell–cell junctions. Phosphorylation at Ser-386 does not switch the specificity of Mgc's GAP activity and is not required for successful cytokinesis. Furthermore, Mgc regulates adherens junction but not tight junction structure, and the ability to regulate adherens junctions is dependent on GAP activity and signaling via the RhoA pathway. Together these results indicate that Mgc's GAP activity down-regulates the active populations of RhoA and Rac1 at localized regions of epithelial cells and is necessary for successful cytokinesis and cell–cell junction structure.
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Affiliation(s)
- Elaina B Breznau
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109
| | - Ansley C Semack
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Tomohito Higashi
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
| | - Ann L Miller
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109 Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109
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29
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Affiliation(s)
- Joydip Das
- Department of Pharmacological
and Pharmaceutical Sciences, College of Pharmacy, University of Houston, 521 Science and Research Building 2, Houston, Texas 77204, United States
| | - Ghazi M. Rahman
- Department of Pharmacological
and Pharmaceutical Sciences, College of Pharmacy, University of Houston, 521 Science and Research Building 2, Houston, Texas 77204, United States
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30
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Pu Y, Kang JH, Sigano DM, Peach M, Lewin NE, Marquez VE, Blumberg PM. Diacylglycerol lactones targeting the structural features that distinguish the atypical C1 domains of protein kinase C ζ and ι from typical C1 domains. J Med Chem 2014; 57:3835-44. [PMID: 24684293 PMCID: PMC4310642 DOI: 10.1021/jm500165n] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Indexed: 01/25/2023]
Abstract
To explore the feasibility of developing ligands targeted to the atypical C1 domains of protein kinase C ζ and ι, we have prepared diacylglycerol lactones substituted with hydrophilic groups on their side chains, which potentially could interact with the arginine residues that distinguish the atypical C1 domains of PKCζ and PKCι from typical C1 domains, and we have measured their binding to mutated versions of the C1b domain of PKCδ that incorporate one or more of these arginine residues. The most selective of the diacylglycerol lactones showed only a 10-fold reduction in binding affinity with the triple arginine mutant (N7R/S10R/L20R) compared to the wild-type, whereas phorbol 12,13-dibutyrate showed a 6000-fold loss of affinity. Molecular modeling confirms that these ligands are indeed able to interact with the arginine residues. Our results show that dramatic changes in selectivity can be obtained through appropriate substitution of diacylglycerol lactones.
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Affiliation(s)
- Yongmei Pu
- Laboratory
of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of
Health, Bethesda, Maryland 20892, United
States
| | - Ji-Hye Kang
- Chemical
Biology Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, National Institutes of Health, Frederick, Maryland 21702, United States
| | - Dina M. Sigano
- Chemical
Biology Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, National Institutes of Health, Frederick, Maryland 21702, United States
| | - Megan
L. Peach
- Chemical
Biology Laboratory, Basic Science Program, Frederick National Laboratory
for Cancer Research, Leidos Biomedical,
Inc., Frederick, Maryland 21702, United
States
| | - Nancy E. Lewin
- Laboratory
of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of
Health, Bethesda, Maryland 20892, United
States
| | - Victor E. Marquez
- Chemical
Biology Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, National Institutes of Health, Frederick, Maryland 21702, United States
| | - Peter M. Blumberg
- Laboratory
of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of
Health, Bethesda, Maryland 20892, United
States
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31
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Kelsey JS, Geczy T, Lewin NE, Kedei N, Hill CS, Selezneva JS, Valle CJ, Woo W, Gorshkova I, Blumberg PM. Charge density influences C1 domain ligand affinity and membrane interactions. Chembiochem 2014; 15:1131-1144. [PMID: 24777910 DOI: 10.1002/cbic.201400041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Indexed: 12/25/2022]
Abstract
The C1 domain, which represents the recognition motif on protein kinase C for the lipophilic second messenger diacylglycerol and its ultrapotent analogues, the phorbol esters, has emerged as a promising therapeutic target for cancer and other indications. Potential target selectivity is markedly enhanced both because binding reflects ternary complex formation between the ligand, C1 domain, and phospholipid, and because binding drives membrane insertion of the C1 domain, permitting aspects of the C1 domain surface outside the binding site, per se, to influence binding energetics. Here, focusing on charged residues identified in atypical C1 domains which contribute to their loss of ligand binding activity, we showed that increasing charge along the rim of the binding cleft of the protein kinase C δ C1 b domain raises the requirement for anionic phospholipids. Correspondingly, it shifts the selectivity of C1 domain translocation to the plasma membrane, which is more negatively charged than internal membranes. This change in localization is most pronounced in the case of more hydrophilic ligands, which provide weaker membrane stabilization than do the more hydrophobic ligands and thus contributes an element to the structure-activity relations for C1 domain ligands. Coexpressing pairs of C1-containing constructs with differing charges each expressing a distinct fluorescent tag provided a powerful tool to demonstrate the effect of increasing charge in the C1 domain.
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Affiliation(s)
- Jessica S Kelsey
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute Building 37, Room 4048, 37 Convent Drive MSC 4255, Bethesda, MD 20892-4255, U.S.A
| | - Tamas Geczy
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute Building 37, Room 4048, 37 Convent Drive MSC 4255, Bethesda, MD 20892-4255, U.S.A
| | - Nancy E Lewin
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute Building 37, Room 4048, 37 Convent Drive MSC 4255, Bethesda, MD 20892-4255, U.S.A
| | - Noemi Kedei
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute Building 37, Room 4048, 37 Convent Drive MSC 4255, Bethesda, MD 20892-4255, U.S.A
| | - Colin S Hill
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute Building 37, Room 4048, 37 Convent Drive MSC 4255, Bethesda, MD 20892-4255, U.S.A
| | - Julia S Selezneva
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute Building 37, Room 4048, 37 Convent Drive MSC 4255, Bethesda, MD 20892-4255, U.S.A
| | - Christopher J Valle
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute Building 37, Room 4048, 37 Convent Drive MSC 4255, Bethesda, MD 20892-4255, U.S.A
| | - Wonhee Woo
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute Building 37, Room 4048, 37 Convent Drive MSC 4255, Bethesda, MD 20892-4255, U.S.A
| | - Inna Gorshkova
- Biomedical Engineering and Physical Science Share Resource Program, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892, U.S.A
| | - Peter M Blumberg
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute Building 37, Room 4048, 37 Convent Drive MSC 4255, Bethesda, MD 20892-4255, U.S.A
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32
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Yamamoto T, Sakai H, Sakane F. EF-hand motifs of diacylglycerol kinase α interact intra-molecularly with its C1 domains. FEBS Open Bio 2014; 4:387-92. [PMID: 24918053 PMCID: PMC4050180 DOI: 10.1016/j.fob.2014.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 04/14/2014] [Accepted: 04/15/2014] [Indexed: 02/02/2023] Open
Abstract
We revealed the intra-molecular interaction of DGKα. The EF-hand motifs of DGKα directly binds to its C1 domains. The intra-molecular interaction was negatively regulated by Ca2+. The intra-molecular interaction is important for the activation mechanism of DGKα.
Diacylglycerol kinase (DGK) α, which is activated by Ca2+, contains a recoverin homology (RVH) domain, tandem repeats of two Ca2+-binding EF-hand motifs, two cysteine-rich C1 domains and the catalytic domain. We previously found that a DGKα mutant lacking the RVH domain and EF-hands was constitutively active and that the N-terminal region of DGKα, consisting of the RVH domain and EF-hand motifs, interacted intra-molecularly with the C-terminal region containing the C1 and catalytic domains. In this study, we narrowed down the interaction regions of DGKα. At the C-terminal region, the C1 domains are responsible for the intra-molecular interaction. At the N-terminal region, the EF-hand motifs mainly contribute to the interaction. Moreover, using highly purified EF-hand motifs and C1 domains, we demonstrate that they directly bind to each other. The co-precipitation of these two domains was clearly attenuated by the addition of Ca2+. These results indicate that the Ca2+-induced dissociation of the intra-molecular interaction between the EF-hand motifs and the C1 domains of DGKα is the key event that regulates the activity of the enzyme.
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Key Words
- C1 domain
- C1Ds, C1 domains
- CR, catalytic region
- Calcium
- DG, diacylglycerol
- DGK, diacylglycerol kinase
- Diacylglycerol kinase
- EF-hand
- EFHs, EF-hand motifs
- EGFP, enhanced green fluorescence protein
- EGTA, ethylene glycol tetraacetic acid
- GST, glutathione S-transferase
- Intra-molecular interaction
- RVH, recoverin homology
- RVHD, RVH domain
- TF, trigger factor
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Affiliation(s)
- Tatsuya Yamamoto
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Hiromichi Sakai
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
| | - Fumio Sakane
- Department of Chemistry, Graduate School of Science, Chiba University, Chiba, Japan
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33
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Zubeldia-Brenner L, Gutierrez-Uzquiza A, Barrio-Real L, Wang H, Kazanietz MG, Leskow FC. β3-chimaerin, a novel member of the chimaerin Rac-GAP family. Mol Biol Rep 2014; 41:2067-76. [PMID: 24430297 DOI: 10.1007/s11033-014-3055-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 01/04/2014] [Indexed: 12/11/2022]
Abstract
Chimaerins are a family of diacylglycerol- and phorbol ester-regulated GTPase activating proteins (GAPs) for the small G-protein Rac. Extensive evidence indicates that these proteins play important roles in development, axon guidance, metabolism, cell motility, and T cell activation. Four isoforms have been reported to-date, which are products of CHN1 (α1- and α2-chimaerins) and CHN2 (β1- and β2-chimaerins) genes. Although these gene products are assumed to be generated by alternative splicing, bioinformatics analysis of the CHN2 gene revealed that β1- and β2-chimaerins are the products of alternative transcription start sites (TSSs) in different promoter regions. Furthermore, we found an additional TSS in CHN2 gene that leads to a novel product, which we named β3-chimaerin. Expression profile analysis revealed predominantly low levels for the β3-chimaerin transcript, with higher expression levels in epididymis, plasma blood leucocytes, spleen, thymus, as well as various areas of the brain. In addition to the prototypical SH2, C1, and Rac-GAP domains, β3-chimaerin has a unique N-terminal domain. Studies in cells established that β3-chimaerin has Rac-GAP activity and is responsive to phorbol esters. The enhanced responsiveness of β3-chimaerin for phorbol ester-induced translocation relative to β2-chimaerin suggests differential ligand accessibility to the C1 domain.
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Affiliation(s)
- Lautaro Zubeldia-Brenner
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, IQUIBICEN-CONICET, Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
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34
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Gutierrez-Uzquiza A, Colon-Gonzalez F, Leonard TA, Canagarajah BJ, Wang H, Mayer BJ, Hurley JH, Kazanietz MG. Coordinated activation of the Rac-GAP β2-chimaerin by an atypical proline-rich domain and diacylglycerol. Nat Commun 2013; 4:1849. [PMID: 23673634 PMCID: PMC3700536 DOI: 10.1038/ncomms2834] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 04/04/2013] [Indexed: 02/08/2023] Open
Abstract
Chimaerins, a family of GTPase activating proteins (GAPs) for the small G-protein Rac, have been implicated in development, neuritogenesis, and cancer. These Rac-GAPs are regulated by the lipid second messenger diacylglycerol (DAG) generated by tyrosine-kinases such as the epidermal growth factor receptor (EGFR). Here we identify an atypical Pro-rich motif in chimaerins that binds to the adaptor protein Nck1. Unlike most Nck1 partners, chimaerins bind to the third SH3 domain of Nck1. This association is mediated by electrostatic interactions of basic residues within the Pro-rich motif with acidic clusters in the SH3 domain. EGF promotes the binding of β2-chimaerin to Nck1 in the cell periphery in a DAG-dependent manner. Moreover, β2-chimaerin translocation to the plasma membrane and its peripheral association with Rac1 requires Nck1. Our studies underscore a coordinated mechanism for β2-chimaerin activation that involves lipid interactions via the C1 domain and protein-protein interactions via the N-terminal Pro-rich region.
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Affiliation(s)
- Alvaro Gutierrez-Uzquiza
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6160, USA
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35
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Abstract
The hardest working complex in animal cell division has a new gig. This extraordinary machine, the centralspindlin complex, works overtime, contributing to nearly every step in cytokinesis. It has now been shown to stabilize an association between the plasma membrane and the midbody microtubules prior to abscission.
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Affiliation(s)
- Michael Glotzer
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA.
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Iwig JS, Vercoulen Y, Das R, Barros T, Limnander A, Che Y, Pelton JG, Wemmer DE, Roose JP, Kuriyan J. Structural analysis of autoinhibition in the Ras-specific exchange factor RasGRP1. eLife 2013; 2:e00813. [PMID: 23908768 PMCID: PMC3728621 DOI: 10.7554/elife.00813] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 06/18/2013] [Indexed: 11/13/2022] Open
Abstract
RasGRP1 and SOS are Ras-specific nucleotide exchange factors that have distinct roles in lymphocyte development. RasGRP1 is important in some cancers and autoimmune diseases but, in contrast to SOS, its regulatory mechanisms are poorly understood. Activating signals lead to the membrane recruitment of RasGRP1 and Ras engagement, but it is unclear how interactions between RasGRP1 and Ras are suppressed in the absence of such signals. We present a crystal structure of a fragment of RasGRP1 in which the Ras-binding site is blocked by an interdomain linker and the membrane-interaction surface of RasGRP1 is hidden within a dimerization interface that may be stabilized by the C-terminal oligomerization domain. NMR data demonstrate that calcium binding to the regulatory module generates substantial conformational changes that are incompatible with the inactive assembly. These features allow RasGRP1 to be maintained in an inactive state that is poised for activation by calcium and membrane-localization signals. DOI:http://dx.doi.org/10.7554/eLife.00813.001 Individual cells within the human body must grow, divide or specialize to perform the tasks required of them. The fates of these cells are often directed by proteins in the Ras family, which detect signals from elsewhere in the body and orchestrate responses within each cell. The activities of these proteins must be tightly controlled, because cancers and developmental diseases can result if Ras proteins are not properly regulated. Binding to the small molecule GTP activates Ras and causes conformational changes that allow it to interact with other proteins in various signaling pathways in the cell. GTP is loaded into Ras by proteins called nucleotide exchange factors, which can replace ‘used’ nucleotides with ‘fresh’ ones to activate Ras. These nucleotide exchange factors are also tightly regulated. For example, the genes for many exchange factors are only switched on after particular signals are received, which can restrict their presence to defined times and locations (e.g., cells or tissues). Also, when activating signals are absent, nucleotide exchange factors commonly reside in the cytoplasm, whereas the Ras proteins remain bound to lipid membranes inside the cell. RasGRP1 is a nucleotide exchange factor that controls the development of immune cells, and leukemia and lupus can result if it is not regulated correctly. However, many questions about RasGRP1 remain unanswered, including how it is able to remain inactive, and how it is activated by various different signals. Iwig et al. have now revealed the mechanisms through which RasGRP1 suppresses Ras signaling in immune cells by solving the structures of two fragments of RasGRP1 and then using a combination of structural, biochemical and cell-based methods to explore how it is activated. These analyses revealed that inactive RasGRP1 adopts a conformation in which one of its regulatory elements blocks access to the Ras binding site. Surprisingly, RasGRP1 can form dimers; this hides the portions of the protein that associate with the membrane and thereby keeps RasGRP1 away from Ras. Iwig et al. also found that two signals, calcium ions and a lipid called diacylglycerol, overcome these inhibitory mechanisms by changing the conformation of RasGRP1 and recruiting it to the membrane. These studies provide a framework for understanding how disease-associated mutations in RasGRP1 bypass the regulatory mechanisms that insure proper immune cell development, and will be critical for developing therapeutic agents that inhibit RasGRP1 activity. DOI:http://dx.doi.org/10.7554/eLife.00813.002
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Affiliation(s)
- Jeffrey S Iwig
- Department of Molecular and Cell Biology , University of California, Berkeley , Berkeley , United States ; California Institute for Quantitative Biosciences , University of California, Berkeley , Berkeley , United States
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Shanmugasundararaj S, Das J, Sandberg WS, Zhou X, Wang D, Messing RO, Bruzik KS, Stehle T, Miller KW. Structural and functional characterization of an anesthetic binding site in the second cysteine-rich domain of protein kinase Cδ*. Biophys J 2013; 103:2331-40. [PMID: 23283232 DOI: 10.1016/j.bpj.2012.10.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 10/24/2012] [Accepted: 10/26/2012] [Indexed: 01/04/2023] Open
Abstract
Elucidating the principles governing anesthetic-protein interactions requires structural determinations at high resolutions not yet achieved with ion channels. Protein kinase C (PKC) activity is modulated by general anesthetics. We solved the structure of the phorbol-binding domain (C1B) of PKCδ complexed with an ether (methoxymethylcycloprane) and with an alcohol (cyclopropylmethanol) at 1.36-Å resolution. The cyclopropane rings of both agents displace a single water molecule in a surface pocket adjacent to the phorbol-binding site, making van der Waals contacts with the backbone and/or side chains of residues Asn-237 to Ser-240. Surprisingly, two water molecules anchored in a hydrogen-bonded chain between Thr-242 and Lys-260 impart elasticity to one side of the binding pocket. The cyclopropane ring takes part in π-acceptor hydrogen bonds with the amide of Met-239. There is a crucial hydrogen bond between the oxygen atoms of the anesthetics and the hydroxyl of Tyr-236. A Tyr-236-Phe mutation results in loss of binding. Thus, both van der Waals interactions and hydrogen-bonding are essential for binding to occur. Ethanol failed to bind because it is too short to benefit from both interactions. Cyclopropylmethanol inhibited phorbol-ester-induced PKCδ activity, but failed to do so in PKCδ containing the Tyr-236-Phe mutation.
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Matsuura A, Lee HH. Crystal structure of GTPase-activating domain from human MgcRacGAP. Biochem Biophys Res Commun 2013; 435:367-72. [PMID: 23665020 DOI: 10.1016/j.bbrc.2013.04.094] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 04/22/2013] [Indexed: 11/29/2022]
Abstract
Cytokinesis in animal cells relies on a centralspindlin complex consisting of male germ cell RacGap (MgcRacGAP) and mitotic kinesin-like protein 1 (MKLP1). Rho GTPases act as molecular switches to regulate the actin cytoskeleton for cytokinesis, of which Rac1 is regulated by MgcRacGAP. In this study, we determined the crystal structure of the GTPase-activating protein (GAP) domain of MgcRacGAP at a resolution of 1.9Å. The conformation of Arg385, which is a key residue for GAP activity, was found to be different from that of previously reported GAP proteins, and MgcRacGAP (residues 348-546) was found to exist as a monomer in solution, according to Stokes radii. We also measured the GAP activity of MgcRacGAP mutants for Rac1.
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Affiliation(s)
- Atsushi Matsuura
- Department of Bio & Nano Chemistry, Kookmin University, Seoul 136-702, Republic of Korea
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Identification of the activator-binding residues in the second cysteine-rich regulatory domain of protein kinase Cθ (PKCθ). Biochem J 2013; 451:33-44. [PMID: 23289588 DOI: 10.1042/bj20121307] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
PKC (protein kinase C) θ is predominantly expressed in T-cells and is critically involved in immunity. Design of PKCθ-selective molecules to manage autoimmune disorders by targeting its activator-binding C1 domain requires the knowledge of its structure and the activator-binding residues. The C1 domain consists of twin C1 domains, C1A and C1B, of which C1B plays a critical role in the membrane translocation and activation of PKCθ. In the present study we determined the crystal structure of PKCθC1B to 1.63 Å (1 Å=0.1 nm) resolution, which showed that Trp(253) at the rim of the activator-binding pocket was orientated towards the membrane, whereas in PKCδC1B the homologous tryptophan residue was orientated away from the membrane. This particular orientation of Trp(253) affects the size of the activator-binding pocket and the membrane affinity. To further probe the structural constraints on activator-binding, five residues lining the activator-binding site were mutated (Y239A, T243A, W253G, L255G and Q258G) and the binding affinities of the PKCθC1B mutants were measured. These mutants showed reduced binding affinities for phorbol ester [PDBu (phorbol 12,13-dibutyrate)] and diacylglycerol [DOG (sn-1,2-dioctanoylglycerol), SAG (sn-1-stearoyl 2-arachidonyl glycerol)]. All five full-length PKCθ mutants exhibited reduced phorbol-ester-induced membrane translocation compared with the wild-type. These results provide insights into the PKCθ activator-binding domain, which will aid in future design of PKCθ-selective molecules.
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Abstract
Small GTPases use GDP/GTP alternation to actuate a variety of functional switches that are pivotal for cell dynamics. The GTPase switch is turned on by GEFs, which stimulate dissociation of the tightly bound GDP, and turned off by GAPs, which accelerate the intrinsically sluggish hydrolysis of GTP. For Ras, Rho, and Rab GTPases, this switch incorporates a membrane/cytosol alternation regulated by GDIs and GDI-like proteins. The structures and core mechanisms of representative members of small GTPase regulators from most families have now been elucidated, illuminating their general traits combined with scores of unique features. Recent studies reveal that small GTPase regulators have themselves unexpectedly sophisticated regulatory mechanisms, by which they process cellular signals and build up specific cell responses. These mechanisms include multilayered autoinhibition with stepwise release, feedback loops mediated by the activated GTPase, feed-forward signaling flow between regulators and effectors, and a phosphorylation code for RhoGDIs. The flipside of these highly integrated functions is that they make small GTPase regulators susceptible to biochemical abnormalities that are directly correlated with diseases, notably a striking number of missense mutations in congenital diseases, and susceptible to bacterial mimics of GEFs, GAPs, and GDIs that take command of small GTPases in infections. This review presents an overview of the current knowledge of these many facets of small GTPase regulation.
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Affiliation(s)
- Jacqueline Cherfils
- Laboratoire d’Enzymologie et Biochimie Structurales, Centre National de la Recherche Scientifique, Centre deRecherche de Gif, Gif-sur-Yvette, France
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Choe Y, Pleasure SJ. The GAP between axon pruning and repulsion. Dev Cell 2012; 23:3-4. [PMID: 22814595 DOI: 10.1016/j.devcel.2012.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Stereotyped axonal pruning and growth cone repulsion, modulators of neuronal connectivity, share many ligands and receptors systems. Riccomagno et al. (2012) show in Cell that common ligands can link functionally specialized downstream pathways, demonstrating that the Rac GAP β2-Chimaerin is needed in Semaphorin-mediated axonal pruning but not growth cone repulsion.
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Affiliation(s)
- Youngshik Choe
- Department of Neurology, Programs in Neuroscience, Developmental and Stem Cell Biology, Institute for Regeneration Medicine, University of California-San Francisco, CA 94158, USA
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The RacGAP β2-Chimaerin selectively mediates axonal pruning in the hippocampus. Cell 2012; 149:1594-606. [PMID: 22726444 DOI: 10.1016/j.cell.2012.05.018] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 04/03/2012] [Accepted: 05/01/2012] [Indexed: 02/08/2023]
Abstract
Axon pruning and synapse elimination promote neural connectivity and synaptic plasticity. Stereotyped pruning of axons that originate in the hippocampal dentate gyrus (DG) and extend along the infrapyramidal tract (IPT) occurs during postnatal murine development by neurite retraction and resembles axon repulsion. The chemorepellent Sema3F is required for IPT axon pruning, dendritic spine remodeling, and repulsion of DG axons. The signaling events that regulate IPT axon pruning are not known. We find that inhibition of the small G protein Rac1 by the Rac GTPase-activating protein (GAP) β2-Chimaerin (β2Chn) mediates Sema3F-dependent pruning. The Sema3F receptor neuropilin-2 selectively binds β2Chn, and ligand engagement activates this GAP to ultimately restrain Rac1-dependent effects on cytoskeletal reorganization. β2Chn is necessary for axon pruning both in vitro and in vivo, but it is dispensable for axon repulsion and spine remodeling. Therefore, a Npn2/β2Chn/Rac1 signaling axis distinguishes DG axon pruning from the effects of Sema3F on repulsion and dendritic spine remodeling.
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Leonard TA, Hurley JH. Regulation of protein kinases by lipids. Curr Opin Struct Biol 2012; 21:785-91. [PMID: 22142590 DOI: 10.1016/j.sbi.2011.07.006] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 07/28/2011] [Indexed: 01/07/2023]
Abstract
Membranes are sites of intense signaling activity within the cell, serving as dynamic scaffolds for the recruitment of signaling molecules and their substrates. The specific and reversible localization of these signaling molecules to membranes is critical for the appropriate activation of downstream signaling pathways. Phospholipid-binding domains, including C1, C2, PH, and PX domains, play critical roles in the membrane targeting of protein kinases. Recent structural studies have identified a new membrane association domain, the Kinase Associated 1 (KA1) domain, which targets a number of yeast and mammalian protein kinases to membranes containing acidic phospholipids. Despite an abundance of localization studies on lipid-binding proteins and structural studies of the isolated lipid-binding domains, the question of how membrane binding is coupled to the activation of the kinase catalytic domain has been virtually untouched. Recently, structural studies on protein kinase C (PKC) have provided some of the first structural insights into the allosteric regulation of protein kinases by lipid second messengers.
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Affiliation(s)
- Thomas A Leonard
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Geczy T, Peach ML, El Kazzouli S, Sigano DM, Kang JH, Valle CJ, Selezneva J, Woo W, Kedei N, Lewin NE, Garfield SH, Lim L, Mannan P, Marquez VE, Blumberg PM. Molecular basis for failure of "atypical" C1 domain of Vav1 to bind diacylglycerol/phorbol ester. J Biol Chem 2012; 287:13137-58. [PMID: 22351766 DOI: 10.1074/jbc.m111.320010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
C1 domains, the recognition motif of the second messenger diacylglycerol and of the phorbol esters, are classified as typical (ligand-responsive) or atypical (not ligand-responsive). The C1 domain of Vav1, a guanine nucleotide exchange factor, plays a critical role in regulation of Vav activity through stabilization of the Dbl homology domain, which is responsible for exchange activity of Vav. Although the C1 domain of Vav1 is classified as atypical, it retains a binding pocket geometry homologous to that of the typical C1 domains of PKCs. This study clarifies the basis for its failure to bind ligands. Substituting Vav1-specific residues into the C1b domain of PKCδ, we identified five crucial residues (Glu(9), Glu(10), Thr(11), Thr(24), and Tyr(26)) along the rim of the binding cleft that weaken binding potency in a cumulative fashion. Reciprocally, replacing these incompatible residues in the Vav1 C1 domain with the corresponding residues from PKCδ C1b (δC1b) conferred high potency for phorbol ester binding. Computer modeling predicts that these unique residues in Vav1 increase the hydrophilicity of the rim of the binding pocket, impairing membrane association and thereby preventing formation of the ternary C1-ligand-membrane binding complex. The initial design of diacylglycerol-lactones to exploit these Vav1 unique residues showed enhanced selectivity for C1 domains incorporating these residues, suggesting a strategy for the development of ligands targeting Vav1.
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Affiliation(s)
- Tamas Geczy
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA
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Miyake N, Demer JL, Shaaban S, Andrews C, Chan WM, Christiansen SP, Hunter DG, Engle EC. Expansion of the CHN1 strabismus phenotype. Invest Ophthalmol Vis Sci 2011; 52:6321-8. [PMID: 21715346 DOI: 10.1167/iovs.11-7950] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE Hyperactivating CHN1 mutations have been described in individuals with Duane retraction syndrome with or without vertical gaze abnormalities. This was a study of five family members with distinctive ocular dysmotility patterns that co-segregated with a novel hyperactivating CHN1 mutation. METHODS Participating members of a family segregating pleomorphic incomitant strabismus underwent ophthalmic examinations, and several underwent high-resolution magnetic resonance imaging (MRI) of the orbits and brain stem. Participant DNA was extracted and amplified for haplotype analysis encompassing the CHN1 region on chromosome 2q31.1, and mutation analysis of the CHN1 gene, which encodes the Rac-GAP signaling protein α2-chimaerin. In vitro functional studies of the co-inherited mutation were performed, including a Rac-GTP activation assay, quantification of α2-chimaerin translocation, and co-immunoprecipitation. RESULTS All five clinically affected family members exhibited monocular or binocular supraduction deficits, three in the absence of Duane retraction syndrome. MRI in four affected individuals demonstrated small or absent abducens nerves in all four, small oculomotor nerve in one, and small optic nerves in three. Superior oblique muscle volume was also decreased in three of the individuals, supporting trochlear nerve hypoplasia. Strabismus segregated with the CHN1 locus and affected individuals harbored a c.443A>T CHN1 mutation (p.Y148F). In vitro, this novel mutation behaved similarly to previously reported CHN1 mutations underlying familial Duane syndrome, hyperactivating α2-chimaerin by enhancing its dimerization and membrane association and lowering total intracellular Rac-GTP. CONCLUSIONS Analysis of the current pedigree expands the phenotypic spectrum of hyperactivating CHN1 mutations to include vertical strabismus and supraduction deficits in the absence of Duane retraction syndrome.
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Affiliation(s)
- Noriko Miyake
- Departments of Neurology, Children’s Hospital Boston, Boston, Massachusetts 02115, USA
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Shaping up the membrane: diacylglycerol coordinates spatial orientation of signaling. Trends Biochem Sci 2011; 36:593-603. [PMID: 21798744 DOI: 10.1016/j.tibs.2011.06.005] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Revised: 06/21/2011] [Accepted: 06/23/2011] [Indexed: 11/23/2022]
Abstract
Diacylglycerol signals by binding and activating C1 domain-containing proteins expressed principally in neuronal and immune tissues. This restricted expression profile suggests that diacylglycerol-regulated signals are particularly relevant in cell-cell communication processes in which active endocytosis and exocytosis take place. Not surprisingly, various experimental approaches have demonstrated a crucial role for diacylglycerol effectors and metabolizing enzymes in the control of immune responses, neuron communication and phagocytosis. Current research delineates a scenario in which coordinated decoding of diacylglycerol signals is translated into complex biological responses such as neuronal plasticity, T cell development or cytolytic killing. Diacylglycerol functions reach maximal diversity in these highly specialized systems in which signal intensity directly regulates distinct biological outcomes. This review brings together the most recent studies, emphasizing the contribution of compartmentalized DAG metabolism to orientated signaling events.
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Chan WM, Miyake N, Zhu-Tam L, Andrews C, Engle EC. Two novel CHN1 mutations in 2 families with Duane retraction syndrome. ACTA ACUST UNITED AC 2011; 129:649-52. [PMID: 21555619 DOI: 10.1001/archophthalmol.2011.84] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To determine the genetic cause of Duane retraction syndrome (DRS) in 2 families segregating DRS as a dominant trait. METHODS Members of 2 unrelated pedigrees were enrolled in a genetic study. Linkage analysis was performed on the CHN1 locus. Probands and family members were screened for CHN1 mutations. RESULTS The 6 affected individuals in the 2 pedigrees have DRS. Both pedigrees are consistent with linkage to the locus. Sequence analysis revealed 2 novel heterozygous missense CHN1 mutations, c.422C>T and c.754C>T, predicted to result in α2-chimaerin amino acid substitutions P141L and P252S, respectively. CONCLUSIONS Genetic analysis of 2 pedigrees revealed 2 novel DRS mutations, bringing the number of DRS pedigrees known to harbor CHN1 from 7 to 9. Both mutations alter residues that participate in intramolecular interactions that stabilize the inactive, closed conformation of α2-chimaerin and, thus, are predicted to result in its hyperactivation. Moreover, amino acid residue P252 was previously reported to be altered to a different residue in a previously reported DRS pedigree; thus, this is the first report of 2 CHN1 mutations altering the same residue, further supporting a gain-of-function etiology. CLINICAL RELEVANCE Members of families segregating DRS as an autosomal dominant trait should be screened for mutations in the CHN1 gene, enhancing genetic counseling and permitting earlier diagnosis.
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Affiliation(s)
- Wai-Man Chan
- Department of Neurology, Children's Hospital Boston, 300 Longwood Ave, Boston, MA 02115, USA
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Abstract
In a recent issue of Cell, Leonard et al. (2011) describe the structure of PKCβII, an AGC kinase, revealing an unanticipated intramolecular autoinhibitory interaction between its C-terminal tail and the diacylglycerol and phorbol ester binding site of its C1b domain.
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Leonard TA, Różycki B, Saidi LF, Hummer G, Hurley JH. Crystal structure and allosteric activation of protein kinase C βII. Cell 2011; 144:55-66. [PMID: 21215369 PMCID: PMC3104240 DOI: 10.1016/j.cell.2010.12.013] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2010] [Revised: 10/29/2010] [Accepted: 12/09/2010] [Indexed: 12/21/2022]
Abstract
Protein kinase C (PKC) isozymes are the paradigmatic effectors of lipid signaling. PKCs translocate to cell membranes and are allosterically activated upon binding of the lipid diacylglycerol to their C1A and C1B domains. The crystal structure of full-length protein kinase C βII was determined at 4.0 Å, revealing the conformation of an unexpected intermediate in the activation pathway. Here, the kinase active site is accessible to substrate, yet the conformation of the active site corresponds to a low-activity state because the ATP-binding side chain of Phe629 of the conserved NFD motif is displaced. The C1B domain clamps the NFD helix in a low-activity conformation, which is reversed upon membrane binding. A low-resolution solution structure of the closed conformation of PKCβII was derived from small-angle X-ray scattering. Together, these results show how PKCβII is allosterically regulated in two steps, with the second step defining a novel protein kinase regulatory mechanism.
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Affiliation(s)
- Thomas A Leonard
- Laboratory of Molecular Biology, National Institutes of Health, Bethesda, MD 20892, USA
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Stalder D, Barelli H, Gautier R, Macia E, Jackson CL, Antonny B. Kinetic studies of the Arf activator Arno on model membranes in the presence of Arf effectors suggest control by a positive feedback loop. J Biol Chem 2010; 286:3873-83. [PMID: 21118813 DOI: 10.1074/jbc.m110.145532] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proteins of the cytohesin/Arno/Grp1 family of Arf activators are positive regulators of the insulin-signaling pathway and control various remodeling events at the plasma membrane. Arno has a catalytic Sec7 domain, which promotes GDP to GTP exchange on Arf, followed by a pleckstrin homology (PH) domain. Previous studies have revealed two functions of the PH domain: inhibition of the Sec7 domain and membrane targeting. Interestingly, the Arno PH domain interacts not only with a phosphoinositide (phosphatidylinositol 4,5-bisphosphate or phosphatidylinositol 3,4,5-trisphosphate) but also with an activating Arf family member, such as Arf6 or Arl4. Using the full-length membrane-bound forms of Arf1 and Arf6 instead of soluble forms, we show here that the membrane environment dramatically affects the mechanism of Arno activation. First, Arf6-GTP stimulates Arno at nanomolar concentrations on liposomes compared with micromolar concentrations in solution. Second, mutations in the PH domain that abolish interaction with Arf6-GTP render Arno completely inactive when exchange reactions are reconstituted on liposomes but have no effect on Arno activity in solution. Third, Arno is activated by its own product Arf1-GTP in addition to a distinct activating Arf isoform. Consequently, Arno activity is strongly modulated by competition with Arf effectors. These results show that Arno behaves as a bistable switch, having an absolute requirement for activation by an Arf protein but, once triggered, becoming highly active through the positive feedback effect of Arf1-GTP. This property of Arno might provide an explanation for its function in signaling pathways that, once triggered, must move forward decisively.
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Affiliation(s)
- Danièle Stalder
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia Antipolis et CNRS, 06560 Valbonne, France
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