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Politiek FA, Turkenburg M, Henneman L, Ofman R, Waterham HR. Molecular and cellular consequences of mevalonate kinase deficiency. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167177. [PMID: 38636615 DOI: 10.1016/j.bbadis.2024.167177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/06/2024] [Accepted: 04/14/2024] [Indexed: 04/20/2024]
Abstract
Mevalonate kinase deficiency (MKD) is an autosomal recessive metabolic disorder associated with recurrent autoinflammatory episodes. The disorder is caused by bi-allelic loss-of-function variants in the MVK gene, which encodes mevalonate kinase (MK), an early enzyme in the isoprenoid biosynthesis pathway. To identify molecular and cellular consequences of MKD, we studied primary fibroblasts from severely affected patients with mevalonic aciduria (MKD-MA) and more mildly affected patients with hyper IgD and periodic fever syndrome (MKD-HIDS). As previous findings indicated that the deficient MK activity in MKD impacts protein prenylation in a temperature-sensitive manner, we compared the subcellular localization and activation of the small Rho GTPases RhoA, Rac1 and Cdc42 in control, MKD-HIDS and MKD-MA fibroblasts cultured at physiological and elevated temperatures. This revealed a temperature-induced altered subcellular localization and activation in the MKD cells. To study if and how the temperature-induced ectopic activation of these signalling proteins affects cellular processes, we performed comparative transcriptome analysis of control and MKD-MA fibroblasts cultured at 37 °C or 40 °C. This identified cell cycle and actin cytoskeleton organization as respectively most down- and upregulated gene clusters. Further studies confirmed that these processes were affected in fibroblasts from both patients with MKD-MA and MKD-HIDS. Finally, we found that, similar to immune cells, the MK deficiency causes metabolic reprogramming in MKD fibroblasts resulting in increased expression of genes involved in glycolysis and the PI3K/Akt/mTOR pathway. We postulate that the ectopic activation of small GTPases causes inappropriate signalling contributing to the molecular and cellular aberrations observed in MKD.
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Affiliation(s)
- Frouwkje A Politiek
- Laboratory Genetic Metabolic Diseases, Department of Laboratory Medicine, Amsterdam University Medical Centers, Location Academic Medical Center, Amsterdam, the Netherlands; Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam, the Netherlands
| | - Marjolein Turkenburg
- Laboratory Genetic Metabolic Diseases, Department of Laboratory Medicine, Amsterdam University Medical Centers, Location Academic Medical Center, Amsterdam, the Netherlands
| | - Linda Henneman
- Laboratory Genetic Metabolic Diseases, Department of Laboratory Medicine, Amsterdam University Medical Centers, Location Academic Medical Center, Amsterdam, the Netherlands; Division of Molecular Pathology, Netherlands Cancer Institute, Amsterdam, the Netherlands
| | - Rob Ofman
- Laboratory Genetic Metabolic Diseases, Department of Laboratory Medicine, Amsterdam University Medical Centers, Location Academic Medical Center, Amsterdam, the Netherlands
| | - Hans R Waterham
- Laboratory Genetic Metabolic Diseases, Department of Laboratory Medicine, Amsterdam University Medical Centers, Location Academic Medical Center, Amsterdam, the Netherlands; Amsterdam Gastroenterology Endocrinology Metabolism, Amsterdam, the Netherlands; Amsterdam Reproduction & Development, Amsterdam, the Netherlands.
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2
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Field MC. Ras superfamily GTPases and signal transduction in Euglena gracilis. Protist 2024; 175:126017. [PMID: 38295671 DOI: 10.1016/j.protis.2024.126017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 12/21/2023] [Accepted: 01/26/2024] [Indexed: 03/13/2024]
Abstract
Biological complexity is challenging to define, but can be considered through one or more features, including overall genome size, number of genes, morphological features, multicellularity, number of life cycle stages and the ability to adapt to different environments. Euglena gracilis meets several of these criteria, with a large genome of ∼38,000 protein coding genes and a considerable ability to survive under many different conditions, some of which can be described as challenging or harsh. Potential molecular exemplars of complexity tying these aspects together are signalling pathways, including GTPases, kinases and ubiquitylation, which increase the functionality of the gene-encoded proteome manyfold. Each of these examples can modulate both protein activity and gene expression. To address the connection between genome size and complexity I have undertaken a brief, and somewhat qualitative, survey of the small ras-like GTPase superfamily of E. gracilis. Unexpectedly, apart from Rab-GTPases which control intracellular transport and organelle identify, the size of the GTPase cohort is modest, and, for example, has not scaled with gene number when compared to the close relatives, trypanosomatids. I suggest that understanding the functions of this protein family will be vital to uncovering the complexity of E. gracilis biology.
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Affiliation(s)
- Mark C Field
- School of Life Sciences, University of Dundee, Dundee, UK; Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic.
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3
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Kin K, Chen ZH, Forbes G, Lawal H, Schilde C, Singh R, Cole C, Barton GJ, Schaap P. The protein kinases of Dictyostelia and their incorporation into a signalome. Cell Signal 2023; 108:110714. [PMID: 37187217 DOI: 10.1016/j.cellsig.2023.110714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/02/2023] [Accepted: 05/12/2023] [Indexed: 05/17/2023]
Abstract
Protein kinases are major regulators of cellular processes, but the roles of most kinases remain unresolved. Dictyostelid social amoebas have been useful in identifying functions for 30% of its kinases in cell migration, cytokinesis, vesicle trafficking, gene regulation and other processes but their upstream regulators and downstream effectors are mostly unknown. Comparative genomics can assist to distinguish between genes involved in deeply conserved core processes and those involved in species-specific innovations, while co-expression of genes as evident from comparative transcriptomics can provide cues to the protein complement of regulatory networks. Genomes and developmental and cell-type specific transcriptomes are available for species that span the 0.5 billion years of evolution of Dictyostelia from their unicellular ancestors. In this work we analysed conservation and change in the abundance, functional domain architecture and developmental regulation of protein kinases across the 4 major taxon groups of Dictyostelia. All data are summarized in annotated phylogenetic trees of the kinase subtypes and accompanied by functional information of all kinases that were experimentally studied. We detected 393 different protein kinase domains across the five studied genomes, of which 212 were fully conserved. Conservation was highest (71%) in the previously defined AGC, CAMK, CK1, CMCG, STE and TKL groups and lowest (26%) in the "other" group of typical protein kinases. This was mostly due to species-specific single gene amplification of "other" kinases. Apart from the AFK and α-kinases, the atypical protein kinases, such as the PIKK and histidine kinases were also almost fully conserved. The phylogeny-wide developmental and cell-type specific expression profiles of the protein kinase genes were combined with profiles from the same transcriptomic experiments for the families of G-protein coupled receptors, small GTPases and their GEFs and GAPs, the transcription factors and for all genes that upon lesion generate a developmental defect. This dataset was subjected to hierarchical clustering to identify clusters of co-expressed genes that potentially act together in a signalling network. The work provides a valuable resource that allows researchers to identify protein kinases and other regulatory proteins that are likely to act as intermediates in a network of interest.
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Affiliation(s)
- Koryu Kin
- Molecular Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom; Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Barcelona, Spain.
| | - Zhi-Hui Chen
- Molecular Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Gillian Forbes
- Molecular Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom; Institut de Génomique Fonctionnelle de Lyon (IGFL), CNRS, École Normale Supérieure de Lyon and Université Claude Bernard Lyon-1, Lyon 69007, France.
| | - Hajara Lawal
- Molecular Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Christina Schilde
- Molecular Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom; D'Arcy Thompson Unit, School of Life Sciences, University of Dundee, DD1 4HN, United Kingdom.
| | - Reema Singh
- Molecular Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom; Computational Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom; Vaccine and Infectious Disease Organization, University of Saskatchewan,120 Veterinary Road, Saskatoon, SK S7N 5E3, Canada.
| | - Christian Cole
- Computational Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom; Population Health and Genomics, School of Medicine, University of Dundee, Ninewells Hospital, Dundee DD1 9SY, United Kingdom
| | - Geoffrey J Barton
- Computational Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
| | - Pauline Schaap
- Molecular Cell and Developmental Biology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom.
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4
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Jiang H, Zu S, Lu Y, Sun Z, Adeerjiang A, Guo Q, Zhang H, Dong C, Wu Q, Ding H, Du D, Wang M, Liu C, Tang Y, Liang Z, Luo C. A RhoA structure with switch II flipped outward revealed the conformational dynamics of switch II region. J Struct Biol 2023; 215:107942. [PMID: 36781028 DOI: 10.1016/j.jsb.2023.107942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/23/2023] [Accepted: 02/08/2023] [Indexed: 02/13/2023]
Abstract
Small GTPase RhoA switches from GTP-bound state to GDP-bound state by hydrolyzing GTP, which is accelerated by GTPases activating proteins (GAPs). However, less study of RhoA structural dynamic changes was conducted during this process, which is essential for understanding the molecular mechanism of GAP dissociation. Here, we solved a RhoA structure in GDP-bound state with switch II flipped outward. Because lacking the intermolecular interactions with guanine nucleotide, we proposed this conformation of RhoA could be an intermediate after GAP dissociation. Further molecular dynamics simulations found the conformational changes of switch regions are indeed existing in RhoA and involved in the regulation of GAP dissociation and GEF recognition. Besides, the guanine nucleotide binding pocket extended to switch II region, indicating a potential "druggable" cavity for RhoA. Taken together, our study provides a deeper understanding of the dynamic properties of RhoA switch regions and highlights the direction for future drug development.
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Affiliation(s)
- Hao Jiang
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China; State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; University of Chinese Academy of Sciences (UCAS), 19 Yuquan Road, Beijing 100049, China
| | - Shijia Zu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; University of Chinese Academy of Sciences (UCAS), 19 Yuquan Road, Beijing 100049, China
| | - Yu Lu
- Center for Systems Biology, Department of Bioinformatics, School of Biology and Basic Medical Sciences, Soochow University, Suzhou 215123, China
| | - Zhongya Sun
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; School of Life Science and Technology, Harbin Institute of Technology, Harbin 150001, China
| | - Akejiang Adeerjiang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; University of Chinese Academy of Sciences (UCAS), 19 Yuquan Road, Beijing 100049, China
| | - Qiao Guo
- Center for Systems Biology, Department of Bioinformatics, School of Biology and Basic Medical Sciences, Soochow University, Suzhou 215123, China
| | - Huimin Zhang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; School of Life Science and Technology, Shanghai Tech University, 100 Haike Road, Shanghai 201210, China
| | - Chen Dong
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; University of Chinese Academy of Sciences (UCAS), 19 Yuquan Road, Beijing 100049, China
| | - Qiqi Wu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
| | - Hong Ding
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
| | - Daohai Du
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
| | - Mingliang Wang
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan 528437, China
| | - Chuanpeng Liu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin 150001, China
| | - Yong Tang
- Ensem Therapeutics, Inc, 200 Boston Ave, Medford, MA 02155, USA
| | - Zhongjie Liang
- Center for Systems Biology, Department of Bioinformatics, School of Biology and Basic Medical Sciences, Soochow University, Suzhou 215123, China.
| | - Cheng Luo
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China; State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; University of Chinese Academy of Sciences (UCAS), 19 Yuquan Road, Beijing 100049, China; School of Life Science and Technology, Shanghai Tech University, 100 Haike Road, Shanghai 201210, China; Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan 528437, China.
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Yu JH, Moon EY, Kim J, Koo JH. Identification of Small GTPases That Phosphorylate IRF3 through TBK1 Activation Using an Active Mutant Library Screen. Biomol Ther (Seoul) 2023; 31:48-58. [PMID: 36579460 PMCID: PMC9810446 DOI: 10.4062/biomolther.2022.119] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 09/22/2022] [Accepted: 09/26/2022] [Indexed: 12/30/2022] Open
Abstract
Interferon regulatory factor 3 (IRF3) integrates both immunological and non-immunological inputs to control cell survival and death. Small GTPases are versatile functional switches that lie on the very upstream in signal transduction pathways, of which duration of activation is very transient. The large number of homologous proteins and the requirement for site-directed mutagenesis have hindered attempts to investigate the link between small GTPases and IRF3. Here, we constructed a constitutively active mutant expression library for small GTPase expression using Gibson assembly cloning. Small-scale screening identified multiple GTPases capable of promoting IRF3 phosphorylation. Intriguingly, 27 of 152 GTPases, including ARF1, RHEB, RHEBL1, and RAN, were found to increase IRF3 phosphorylation. Unbiased screening enabled us to investigate the sequence-activity relationship between the GTPases and IRF3. We found that the regulation of IRF3 by small GTPases was dependent on TBK1. Our work reveals the significant contribution of GTPases in IRF3 signaling and the potential role of IRF3 in GTPase function, providing a novel therapeutic approach against diseases with GTPase overexpression or active mutations, such as cancer.
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Affiliation(s)
- Jae-Hyun Yu
- Department of Pharmacology and Department of Biomedicine & Health Sciences, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea,College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 08826, Republic of Korea
| | - Eun-Yi Moon
- Department of Bioscience and Biotechnology, Sejong University, Seoul 05006, Republic of Korea
| | - Jiyoon Kim
- Department of Pharmacology and Department of Biomedicine & Health Sciences, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea,Corresponding Authors E-mail: (Kim J), (Koo JH), Tel: +82-2-3147-8358 (Kim J), +82-2-880-7839 (Koo JH), Fax: +82-2-536-2485 (Kim J), +82-2-888-9122 (Koo JH)
| | - Ja Hyun Koo
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 08826, Republic of Korea,Corresponding Authors E-mail: (Kim J), (Koo JH), Tel: +82-2-3147-8358 (Kim J), +82-2-880-7839 (Koo JH), Fax: +82-2-536-2485 (Kim J), +82-2-888-9122 (Koo JH)
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Samuel V, Rajeev T, Ramesh L, Sundararaman A. Integrin receptor trafficking in health and disease. Prog Mol Biol Transl Sci 2023; 196:271-302. [PMID: 36813362 DOI: 10.1016/bs.pmbts.2022.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Integrins are a family of 24 different heterodimers that are indispensable for multicellular life. Cell polarity, adhesion and migration are controlled by integrins delivered to the cell surface which in turn is regulated by the exo- and endocytic trafficking of integrins. The deep integration between trafficking and cell signaling determines the spatial and temporal output from any biochemical cue. Integrin trafficking plays a key role in development and many pathological conditions, especially cancer. Several novel regulators of integrin traffic have been discovered in recent times, including a novel class of integrin carrying vesicles, the intracellular nanovesicles (INVs). The tight regulation of trafficking pathways by cell signaling, where kinases phosphorylate key small GTPases in the trafficking pathway enable coordination of cell response to the extracellular milieu. Integrin heterodimer expression and trafficking differ in different tissues and contexts. In this Chapter, we discuss recent studies on integrin trafficking and its contribution to normal physiological and pathophysiological states.
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Kitzinger R, Fritz G, Henninger C. Nuclear RAC1 is a modulator of the doxorubicin-induced DNA damage response. Biochim Biophys Acta Mol Cell Res 2022; 1869:119320. [PMID: 35817175 DOI: 10.1016/j.bbamcr.2022.119320] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 06/17/2022] [Accepted: 06/22/2022] [Indexed: 06/15/2023]
Abstract
Rho GTPases like RAC1 are localized on the inner side of the outer cell membrane where they act as molecular switches that can trigger signal transduction pathways in response to various extracellular stimuli. Nuclear functions of RAC1 were identified that are related to mitosis, cell cycle arrest and apoptosis. Previously, we showed that RAC1 plays a role in the doxorubicin (Dox)-induced DNA damage response (DDR). In this context it is still unknown whether cytosolic RAC1 modulates the Dox-induced DDR or if a nuclear fraction of RAC1 is involved. Here, we silenced RAC1 in mouse embryonic fibroblasts (MEF) pharmacologically with EHT1864 or by using siRNA against Rac1. Additionally, we transfected MEF with RAC1 mutants (wild-type, dominant-negative, constitutively active) containing a nuclear localization sequence (NLS). Afterwards, we analysed the Dox-induced DDR by evaluation of fluorescent nuclear γH2AX and 53BP1 foci formation, as well as by detection of activated proteins of the DDR by western blot to elucidate the role of nuclear RAC1 in the DDR. Treatment with EHT1864 as well as Rac1 knock-down reduced the Dox-induced DSB-formation to a similar extent. Enhanced nuclear localization of dominant-negative as well as constitutively active RAC1 mimicked these effects. Expression of the RAC1 mutants altered the Dox-induced amount of pP53 and pKAP1 protein. The observed effects were independent of S1981 ATM phosphorylation. We conclude that RAC1 is required for a substantial activation of the Dox-induced DDR and balanced levels of active/inactive RAC1 inside the nucleus are a prerequisite for this response.
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Affiliation(s)
- Rebekka Kitzinger
- Institute of Toxicology, Medical Faculty of the Heinrich Heine University Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany
| | - Gerhard Fritz
- Institute of Toxicology, Medical Faculty of the Heinrich Heine University Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany
| | - Christian Henninger
- Institute of Toxicology, Medical Faculty of the Heinrich Heine University Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany.
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Rachubik P, Szrejder M, Rogacka D, Typiak M, Audzeyenka I, Kasztan M, Pollock DM, Angielski S, Piwkowska A. Insulin controls cytoskeleton reorganization and filtration barrier permeability via the PKGIα-Rac1-RhoA crosstalk in cultured rat podocytes. Biochim Biophys Acta Mol Cell Res 2022; 1869:119301. [PMID: 35642843 DOI: 10.1016/j.bbamcr.2022.119301] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 05/16/2022] [Accepted: 05/19/2022] [Indexed: 06/15/2023]
Abstract
Podocyte foot processes are an important cellular layer of the glomerular barrier that regulates glomerular permeability. Insulin via the protein kinase G type Iα (PKGIα) signaling pathway regulates the balance between contractility and relaxation (permeability) of the podocyte barrier by regulation of the actin cytoskeleton. This mechanism was shown to be disrupted in diabetes. Rho family guanosine-5'-triphosphates (GTPases) are dynamic modulators of the actin cytoskeleton and expressed in cells that form the glomerular filtration barrier. Thus, changes in Rho GTPase activity may affect glomerular permeability to albumin. The present study showed that Rho family GTPases control podocyte migration and permeability. Moreover these processes are regulated by insulin in PKGIα-dependent manner. Modulation of the PKGI-dependent activity of Rac1 and RhoA GTPases with inhibitors or small-interfering RNA impair glomerular permeability to albumin. We also demonstrated this mechanism in obese, insulin-resistant Zucker rats. We propose that PKGIα-Rac1-RhoA crosstalk is necessary in proper organization of the podocyte cytoskeleton and consequently the stabilization of glomerular architecture and regulation of filtration barrier permeability.
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Affiliation(s)
- Patrycja Rachubik
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland
| | - Maria Szrejder
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland
| | - Dorota Rogacka
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland; University of Gdańsk, Faculty of Chemistry, Department of Molecular Biotechnology, Gdańsk, Poland
| | - Marlena Typiak
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland; University of Gdańsk, Faculty of Biology, Department of General and Medical Biochemistry, Gdańsk, Poland
| | - Irena Audzeyenka
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland; University of Gdańsk, Faculty of Chemistry, Department of Molecular Biotechnology, Gdańsk, Poland
| | - Małgorzata Kasztan
- Cardio-Renal Physiology and Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - David M Pollock
- Cardio-Renal Physiology and Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Stefan Angielski
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland
| | - Agnieszka Piwkowska
- Mossakowski Medical Research Institute, Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland; University of Gdańsk, Faculty of Chemistry, Department of Molecular Biotechnology, Gdańsk, Poland.
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Alves LB, Castillo-Ordoñez WO, Giuliatti S. Virtual screening and molecular dynamics study of natural products against Rab10 for the treatment of Alzheimer's disease. J Biomol Struct Dyn 2022:1-21. [PMID: 35994325 DOI: 10.1080/07391102.2022.2112079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder associated with aging. Various enzymatic targets have been and are still being studied in an attempt to discover new drugs for the treatment of AD; however, Rab GTPases are still relatively unexplored. These enzymes regulate cellular processes by alternating of GDP and GTP nucleotides. In vitro studies have shown that the knockdown of Rab10 reduces the production of Aβ40 and Aβ42 peptides, making it a promising target for the treatment of AD. In order to identify potential Rab10 inhibitors, the structure-based virtual screening (SBVS) was used considering a subset of 80763 natural products obtained from ZINC15 database. Tertiary structure of Rab10 was obtained from the Protein Data Bank and the Autodock Vina program was used in the SBVS to filter potential bioactive substances against this enzyme. The SBVS protocol was validated by redocking the co-crystallized GNP and the binding energies of the GDP and GTP were used as controls in the pharmacodynamic analysis. Thus, it was possible to select 45 compounds with binding energy less or equal -11 kcal.mol-1. ADME/T properties of these compounds were evaluated by the SwissADME program, where it was possible to identify 6 promising molecules. The resulting complexes were subjected to molecular dynamics simulations to analyze the pharmacodynamics over time. The results suggest that the compound ZINC4090657 (derived from quinolizidine) and the compounds ZINC4000106 and ZINC0630250 (derived from coumarin) have favorable pharmacological characteristics for the inhibition of Rab10, with ZINC4090657 being the most promising one. Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Levy Bueno Alves
- Department of Genetics, University of São Paulo Ribeirão Preto, Ribeirão Preto, Brazil
| | | | - Silvana Giuliatti
- Department of Genetics, University of São Paulo Ribeirão Preto, Ribeirão Preto, Brazil
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10
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Delgado MG, Rivera CA, Lennon-Duménil AM. Macropinocytosis and Cell Migration: Don't Drink and Drive…. Subcell Biochem 2022; 98:85-102. [PMID: 35378704 DOI: 10.1007/978-3-030-94004-1_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Macropinocytosis is a nonspecific mechanism by which cells compulsively "drink" the surrounding extracellular fluids in order to feed themselves or sample the molecules therein, hence gaining information about their environment. This process is cell-intrinsically incompatible with the migration of many cells, implying that the two functions are antagonistic. The migrating cell uses a molecular switch to stop and explore its surrounding fluid by macropinocytosis, after which it employs the same molecular machinery to start migrating again to examine another location. This cycle of migration/macropinocytosis allows cells to explore tissues, and it is key to a range of physiological processes. Evidence of this evolutionarily conserved antagonism between the two processes can be found in several cell types-immune cells, for example, being particularly adept-and ancient organisms (e.g., the social amoeba Dictyostelium discoideum). How macropinocytosis and migration are negatively coupled is the subject of this chapter.
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11
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Mallery EL, Yanagisawa M, Zhang C, Lee Y, Robles LM, Alonso JM, Szymanski DB. Tandem C2 domains mediate dynamic organelle targeting of a DOCK family guanine nucleotide exchange factor. J Cell Sci 2022; 135:275003. [PMID: 35194638 DOI: 10.1242/jcs.259825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 02/11/2022] [Indexed: 11/20/2022] Open
Abstract
Multicellular organisms use DOCK family guanine nucleotide exchange factors to activate Rac/Rho-of-Plants small GTPases and coordinate cell shape change. In developing tissues, DOCK signals integrate cell-cell interactions with cytoskeleton remodeling, and the GEFs cluster reversibly at specific organelle surfaces to orchestrate cytoskeletal reorganization. The domain organizations among DOCK orthologs are diverse, and the mechanisms of localization control are poorly understood. Here we use combinations of transgene complementation and live cell imaging assays to uncover an evolutionarily conserved and essential localization determinant in the DOCK-GEF named SPIKE1. The SPIKE1-DHR3 domain is sufficient for organelle association in vivo, and displays a complicated lipid binding selectivity for both phospholipid head groups and fatty acid chain saturation. SPIKE1-DHR3 is predicted to adopt a C2-domain structure and functions as part of tandem C2 array that enables reversible clustering at the cell apex. This work provides mechanistic insight into how DOCK GEFs sense compositional and biophysical membrane properties at the interface of two organelle systems.
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Affiliation(s)
- Eileen L Mallery
- Departments of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA
| | - Makoto Yanagisawa
- Departments of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA
| | - Chunhua Zhang
- Departments of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA.,Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA
| | - Youngwoo Lee
- Departments of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA.,Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA
| | - Linda M Robles
- Department of Plant & Microbial Biology, North Carolina State University, Raleigh, NC, 27695, USA
| | - Jose M Alonso
- Department of Plant & Microbial Biology, North Carolina State University, Raleigh, NC, 27695, USA
| | - Daniel B Szymanski
- Departments of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA.,Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA.,Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
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12
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Yin G, Lv G, Zhang J, Jiang H, Lai T, Yang Y, Ren Y, Wang J, Yi C, Chen H, Huang Y, Xiao C. Early-stage structure-based drug discovery for small GTPases by NMR spectroscopy. Pharmacol Ther 2022; 236:108110. [PMID: 35007659 DOI: 10.1016/j.pharmthera.2022.108110] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 01/04/2022] [Accepted: 01/05/2022] [Indexed: 12/13/2022]
Abstract
Small GTPase or Ras superfamily, including Ras, Rho, Rab, Ran and Arf, are fundamental in regulating a wide range of cellular processes such as growth, differentiation, migration and apoptosis. They share structural and functional similarities for binding guanine nucleotides and hydrolyzing GTP. Dysregulations of Ras proteins are involved in the pathophysiology of multiple human diseases, however there is still a stringent need for effective treatments targeting these proteins. For decades, small GTPases were recognized as 'undruggable' targets due to their complex regulatory mechanisms and lack of deep pockets for ligand binding. NMR has been critical in deciphering the structural and dynamic properties of the switch regions that are underpinning molecular switch functions of small GTPases, which pave the way for developing new effective inhibitors. The recent progress of drug or lead molecule development made for small GTPases profoundly delineated how modern NMR techniques reshape the field of drug discovery. In this review, we will summarize the progress of structural and dynamic studies of small GTPases, the NMR techniques developed for structure-based drug screening and their applications in early-stage drug discovery for small GTPases.
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Affiliation(s)
- Guowei Yin
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen 518107, China.
| | - Guohua Lv
- Division of Histology & Embryology, Medical College, Jinan University, Guangzhou 511486, Guangdong, China
| | - Jerry Zhang
- University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27516, USA
| | - Hongmei Jiang
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen 518107, China
| | - Tianqi Lai
- Division of Histology & Embryology, Medical College, Jinan University, Guangzhou 511486, Guangdong, China
| | - Yushan Yang
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen 518107, China
| | - Yong Ren
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen 518107, China
| | - Jing Wang
- College of Life Sciences, Northwest University, Xi'an 710069, Shaanxi, China
| | - Chenju Yi
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen 518107, China
| | - Hao Chen
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, Biomedical Informatics & Genomics Center, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, PR China; Research Institute of Xi'an Jiaotong University, Zhejiang, Hangzhou, Zhejiang Province 311215, PR China
| | - Yun Huang
- Howard Hughes Medical Institute, Chevy Chase 20815, MD, USA; Department of Physiology & Biophysics, Weill Cornell Medicine, New York 10065, NY, USA.
| | - Chaoni Xiao
- College of Life Sciences, Northwest University, Xi'an 710069, Shaanxi, China.
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13
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Jeong A, Cheng S, Zhong R, Bennett DA, Bergö MO, Li L. Protein farnesylation is upregulated in Alzheimer's human brains and neuron-specific suppression of farnesyltransferase mitigates pathogenic processes in Alzheimer's model mice. Acta Neuropathol Commun 2021; 9:129. [PMID: 34315531 PMCID: PMC8314463 DOI: 10.1186/s40478-021-01231-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 07/16/2021] [Indexed: 11/10/2022] Open
Abstract
The pathogenic mechanisms underlying the development of Alzheimer's disease (AD) remain elusive and to date there are no effective prevention or treatment for AD. Farnesyltransferase (FT) catalyzes a key posttranslational modification process called farnesylation, in which the isoprenoid farnesyl pyrophosphate is attached to target proteins, facilitating their membrane localization and their interactions with downstream effectors. Farnesylated proteins, including the Ras superfamily of small GTPases, are involved in regulating diverse physiological and pathological processes. Emerging evidence suggests that isoprenoids and farnesylated proteins may play an important role in the pathogenesis of AD. However, the dynamics of FT and protein farnesylation in human brains and the specific role of neuronal FT in the pathogenic progression of AD are not known. Here, using postmortem brain tissue from individuals with no cognitive impairment (NCI), mild cognitive impairment (MCI), or Alzheimer's dementia, we found that the levels of FT and membrane-associated H-Ras, an exclusively farnesylated protein, and its downstream effector ERK were markedly increased in AD and MCI compared with NCI. To elucidate the specific role of neuronal FT in AD pathogenesis, we generated the transgenic AD model APP/PS1 mice with forebrain neuron-specific FT knockout, followed by a battery of behavioral assessments, biochemical assays, and unbiased transcriptomic analysis. Our results showed that the neuronal FT deletion mitigates memory impairment and amyloid neuropathology in APP/PS1 mice through suppressing amyloid generation and reversing the pathogenic hyperactivation of mTORC1 signaling. These findings suggest that aberrant upregulation of protein farnesylation is an early driving force in the pathogenic cascade of AD and that targeting FT or its downstream signaling pathways presents a viable therapeutic strategy against AD.
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14
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Killoran RC, Smith MJ. NMR Detection Methods for Profiling RAS Nucleotide Cycling. Methods Mol Biol 2021; 2262:169-182. [PMID: 33977476 DOI: 10.1007/978-1-0716-1190-6_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
RAS oncoproteins exhibit a switch-like behavior to drive diverse signaling cascades. In the active GTP-bound state, a conformational change occurs in these enzymes that enables interaction with downstream effectors. Nucleotide-dependent conformational exchange is easily detected with real-time NMR (RT-NMR) spectroscopy. RT-NMR has been firmly established as an effective assay to measure RAS oncoprotein nucleotide exchange and GTP hydrolysis kinetics and can further determine the regulatory activity of guanine exchange factors (GEFs) and GTPase activating proteins (GAPs). It is now possible to multiplex these assays, allowing for the precise monitoring of activation states for mixtures of RAS oncoproteins or other RAS superfamily GTPases. Here, we describe the protocols necessary to express and purify isotopically labeled RAS and detail how to carry out an RT-NMR assay on a singular RAS protein or on a mixture of small GTPases.
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Affiliation(s)
- Ryan C Killoran
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada
| | - Matthew J Smith
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC, Canada. .,Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada.
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15
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Kopra K, Härmä H. Methods to Monitor Ras Activation State. Methods Mol Biol 2021; 2262:137-67. [PMID: 33977475 DOI: 10.1007/978-1-0716-1190-6_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Various biochemical methods have been introduced to detect and characterize small GTPases and Ras. Luminescence-based techniques cover most of the currently used methods, utilizing single- or multi-luminophore-conjugated molecules and external probes. Here we describe methods enabling Ras activity and activation state monitoring in vitro. This chapter focuses mainly on luminescence-based techniques.
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16
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Thies KA, Cole MW, Schafer RE, Spehar JM, Richardson DS, Steck SA, Das M, Lian AW, Ray A, Shakya R, Knoblaugh SE, Timmers CD, Ostrowski MC, Chakravarti A, Sizemore GM, Sizemore ST. The small G-protein RalA promotes progression and metastasis of triple-negative breast cancer. Breast Cancer Res 2021; 23:65. [PMID: 34118960 PMCID: PMC8196523 DOI: 10.1186/s13058-021-01438-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 05/13/2021] [Indexed: 02/01/2023] Open
Abstract
Background Breast cancer (BC) is the most common cancer in women and the leading cause of cancer-associated mortality in women. In particular, triple-negative BC (TNBC) has the highest rate of mortality due in large part to the lack of targeted treatment options for this subtype. Thus, there is an urgent need to identify new molecular targets for TNBC treatment. RALA and RALB are small GTPases implicated in growth and metastasis of a variety of cancers, although little is known of their roles in BC. Methods The necessity of RALA and RALB for TNBC tumor growth and metastasis were evaluated in vivo using orthotopic and tail-vein models. In vitro, 2D and 3D cell culture methods were used to evaluate the contributions of RALA and RALB during TNBC cell migration, invasion, and viability. The association between TNBC patient outcome and RALA and RALB expression was examined using publicly available gene expression data and patient tissue microarrays. Finally, small molecule inhibition of RALA and RALB was evaluated as a potential treatment strategy for TNBC in cell line and patient-derived xenograft (PDX) models. Results Knockout or depletion of RALA inhibited orthotopic primary tumor growth, spontaneous metastasis, and experimental metastasis of TNBC cells in vivo. Conversely, knockout of RALB increased TNBC growth and metastasis. In vitro, RALA and RALB had antagonistic effects on TNBC migration, invasion, and viability with RALA generally supporting and RALB opposing these processes. In BC patient populations, elevated RALA but not RALB expression is significantly associated with poor outcome across all BC subtypes and specifically within TNBC patient cohorts. Immunohistochemical staining for RALA in patient cohorts confirmed the prognostic significance of RALA within the general BC population and the TNBC population specifically. BQU57, a small molecule inhibitor of RALA and RALB, decreased TNBC cell line viability, sensitized cells to paclitaxel in vitro and decreased tumor growth and metastasis in TNBC cell line and PDX models in vivo. Conclusions Together, these data demonstrate important but paradoxical roles for RALA and RALB in the pathogenesis of TNBC and advocate further investigation of RALA as a target for the precise treatment of metastatic TNBC. Supplementary Information The online version contains supplementary material available at 10.1186/s13058-021-01438-3.
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Affiliation(s)
- Katie A Thies
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiation Oncology, The Ohio State University, 646A TMRF, 420 W. 12th Avenue, Columbus, OH, 43210, USA
| | - Matthew W Cole
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiation Oncology, The Ohio State University, 646A TMRF, 420 W. 12th Avenue, Columbus, OH, 43210, USA
| | - Rachel E Schafer
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiation Oncology, The Ohio State University, 646A TMRF, 420 W. 12th Avenue, Columbus, OH, 43210, USA
| | - Jonathan M Spehar
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiation Oncology, The Ohio State University, 646A TMRF, 420 W. 12th Avenue, Columbus, OH, 43210, USA
| | - Dillon S Richardson
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiation Oncology, The Ohio State University, 646A TMRF, 420 W. 12th Avenue, Columbus, OH, 43210, USA
| | - Sarah A Steck
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiation Oncology, The Ohio State University, 646A TMRF, 420 W. 12th Avenue, Columbus, OH, 43210, USA
| | - Manjusri Das
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiation Oncology, The Ohio State University, 646A TMRF, 420 W. 12th Avenue, Columbus, OH, 43210, USA
| | - Arthur W Lian
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiation Oncology, The Ohio State University, 646A TMRF, 420 W. 12th Avenue, Columbus, OH, 43210, USA
| | - Alo Ray
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiation Oncology, The Ohio State University, 646A TMRF, 420 W. 12th Avenue, Columbus, OH, 43210, USA
| | - Reena Shakya
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.,Target Validation Shared Resource, The Ohio State University, Columbus, OH, 43210, USA
| | - Sue E Knoblaugh
- Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, 43210, USA
| | - Cynthia D Timmers
- The Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, 29425, USA.,Division of Hematology and Oncology, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Michael C Ostrowski
- The Hollings Cancer Center, Medical University of South Carolina, Charleston, SC, 29425, USA.,Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC, 29425, USA
| | - Arnab Chakravarti
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiation Oncology, The Ohio State University, 646A TMRF, 420 W. 12th Avenue, Columbus, OH, 43210, USA
| | - Gina M Sizemore
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA.,Department of Radiation Oncology, The Ohio State University, 646A TMRF, 420 W. 12th Avenue, Columbus, OH, 43210, USA
| | - Steven T Sizemore
- Arthur G. James Comprehensive Cancer Center, The Ohio State University, Columbus, OH, 43210, USA. .,Department of Radiation Oncology, The Ohio State University, 646A TMRF, 420 W. 12th Avenue, Columbus, OH, 43210, USA.
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17
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Abstract
The intestinal epithelium acts as a physical barrier that separates the intestinal microbiota from the host and is critical for preserving intestinal homeostasis. The barrier is formed by tightly linked intestinal epithelial cells (IECs) (i.e. enterocytes, goblet cells, neuroendocrine cells, tuft cells, Paneth cells, and M cells), which constantly self-renew and shed. IECs also communicate with microbiota, coordinate innate and adaptive effector cell functions. In this review, we summarize the signaling pathways contributing to intestinal cell fates and homeostasis functions. We focus especially on intestinal stem cell proliferation, cell junction formation, remodelling, hypoxia, the impact of intestinal microbiota, the immune system, inflammation, and metabolism. Recognizing the critical role of KRAS mutants in colorectal cancer, we highlight the connections of KRAS signaling pathways in coordinating these functions. Furthermore, we review the impact of KRAS colorectal cancer mutants on pathway rewiring associated with disruption and dysfunction of the normal intestinal homeostasis. Given that KRAS is still considered undruggable and the development of treatments that directly target KRAS are unlikely, we discuss the suitability of targeting pathways downstream of KRAS as well as alterations of cell extrinsic/microenvironmental factors as possible targets for modulating signaling pathways in colorectal cancer. Video Abstract
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Affiliation(s)
- Camille Ternet
- School of Medicine, Systems Biology Ireland, and UCD Charles Institute of Dermatology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Christina Kiel
- School of Medicine, Systems Biology Ireland, and UCD Charles Institute of Dermatology, University College Dublin, Belfield, Dublin 4, Ireland.
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18
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Choudhury S, Mansi, Muthusamy SK, Padaria JC, Dalal M. Genome-wide identification of Ran GTPase family genes from wheat (T. aestivum) and their expression profile during developmental stages and abiotic stress conditions. Funct Integr Genomics 2021; 21:239-50. [PMID: 33609188 DOI: 10.1007/s10142-021-00773-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 02/02/2021] [Accepted: 02/09/2021] [Indexed: 10/22/2022]
Abstract
Maintenance of growth is important for sustaining yield under stress conditions. Hence, identification of genes involved in cell division and growth under abiotic stress is utmost important. Ras-related nuclear protein (Ran) is a small GTPase required for nucleocytoplasmic transport, mitotic progression, and nuclear envelope assembly in plants. In the present study, two Ran GTPase genes TaRAN1 and TaRAN2 were identified though genome-wide analysis in wheat (T. aestivum). Comparative analysis of Ran GTPases from wheat, barley, rice, maize, sorghum, and Arabidopsis revealed similar gene structure within phylogenetic clades and highly conserved protein structure. Expression analysis from expVIP platform showed ubiquitous expression of TaRAN genes across tissues and developmental stages. Under biotic and abiotic stresses, TaRAN1 expression was largely unaltered, while TaRAN2 showed stress specific response. In qRT-PCR analysis, TaRAN1 showed significantly higher expression as compared to TaRAN2 in shoot and root at seedling, vegetative, and reproductive stages. During progressive drought stress, TaRAN1 and TaRAN2 expression increase during early stress and restored to control level expression at higher stress levels in shoot. The steady-state level of transcripts was maintained to that of control in roots under drought stress. Under cold stress, expression of both the TaRAN genes decreased significantly at 3 h and became similar to control at 6 h in shoots, while salt stress significantly reduced the expression of TaRAN genes in shoots. The analysis suggests differential regulation of TaRAN genes under developmental stages and abiotic stresses. Delineating the molecular functions of Ran GTPases will help unravel the mechanism of stress induced growth inhibition in wheat.
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19
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Xie B, Jung C, Chandra M, Engel A, Kendall AK, Jackson LP. The Glo3 GAP crystal structure supports the molecular niche model for ArfGAPs in COPI coats. Adv Biol Regul 2021; 79:100781. [PMID: 33436318 PMCID: PMC7920988 DOI: 10.1016/j.jbior.2020.100781] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/16/2020] [Accepted: 12/21/2020] [Indexed: 11/27/2022]
Abstract
Arf GTPase activating (ArfGAP) proteins are critical regulatory and effector proteins in membrane trafficking pathways. Budding yeast contain two ArfGAP proteins (Gcs1 and Glo3) implicated in COPI coat function at the Golgi, and yeast require Glo3 catalytic function for viability. A new X-ray crystal structure of the Glo3 GAP domain was determined at 2.1 Å resolution using molecular replacement methods. The structure reveals a Cys4-family zinc finger motif with an invariant residue (R59) positioned to act as an "arginine finger" during catalysis. Comparisons among eukaryotic GAP domains show a key difference between ArfGAP1 and ArfGAP2/3 family members in the final helix located within the domain. Conservation at both the sequence and structural levels suggest the Glo3 GAP domain interacts with yeast Arf1 switch I and II regions to promote catalysis. Together, the structural data presented here provide additional evidence for placing Glo3 near Arf1 triads within membrane-assembled COPI coats and further support the molecular niche model for COPI coat regulation by ArfGAPs.
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Affiliation(s)
- Boyang Xie
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Christian Jung
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Mintu Chandra
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Andrew Engel
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Amy K Kendall
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Lauren P Jackson
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA; Department of Biochemistry, Vanderbilt University, Nashville, TN, USA.
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20
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Abstract
The function of lipid-anchored small GTPases RAS proteins is mostly compartmentalized to the plasma membrane (PM). Complex biophysical interactions between the C-terminal membrane-anchoring domains of RAS isoforms and PM lipids drive spatial segregation of RAS molecules in the formation of nanometer-sized domains, termed as nanoclusters. These RAS/lipid proteolipid nano-assemblies are the main sites for efficient effector recruitment and signal transduction. Here, we describe a super-resolution imaging method to quantify the nanometer-sized nanoclustering of RAS over a length scale between 8 and 240 nm on intact PM sheets of mammalian cells. Detailed molecular spatial distribution parameters, including the extent of nanoclustering, average cluster size, clustered fraction, and population distribution can be obtained by the univariate spatial distribution analysis. Intermolecular associations between different RAS isoforms, RAS and various PM lipids, as well as RAS and diverse effectors can be quantified via bivariate co-localization analysis.
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Affiliation(s)
- Yong Zhou
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, USA.
| | - John F Hancock
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX, USA
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21
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Zhou J, Tan Y, Zhang Y, Tong A, Shen X, Sun X, Jia D, Sun Q. GEF-independent Ran activation shifts a fraction of the protein to the cytoplasm and promotes cell proliferation. Mol Biomed 2020; 1:18. [PMID: 35006421 PMCID: PMC8607414 DOI: 10.1186/s43556-020-00011-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 09/29/2020] [Indexed: 02/08/2023] Open
Abstract
Ran (Ras-related nuclear protein) plays several important roles in nucleo-cytoplasmic transport, mitotic spindle formation, nuclear envelope/nuclear pore complex assembly, and other functions in the cytoplasm, as well as in cellular transformation when switched on. Unlike other members of the GTPase superfamily, Ran binds more tightly to GDP than to GTP due to the presence of an auto-inhibitory C-terminal tail. Multiple missense mutations in the C-terminus of Ran occur in cancers, but their biological significance remains unclear. Here, the quantitative GDP/GTP binding preference of four engineered mutations with unstable C-termini was analyzed using a devised mant-GDP dissociation assay. The results showed that the impact of different C-terminal mutations depends on multiple factors. Although these mutants were more GTP-loaded in human cells, they were shown to be more cytoplasmic, and to support nuclear transport with minimally or partially reduced efficiency. Further, several Ran cancer mutants were compromised in autoinhibition, slightly more GTP-bound, more cytoplasmic, and enhanced the proliferation of A549 and HeLa cells in vitro. Thus, our work reveals a new route of Ran activation independent of guanine nucleotide exchange factor (GEF), which may account for the hyper-proliferation induced by Ran cancer mutations.
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Affiliation(s)
- Jinhan Zhou
- Department of Pathology, State Key Laboratory of Biotherapy and Cancer Centre, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu, 610041, China
| | - Yuping Tan
- Department of Pathology, State Key Laboratory of Biotherapy and Cancer Centre, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu, 610041, China
| | - Yuqing Zhang
- Department of Pathology, State Key Laboratory of Biotherapy and Cancer Centre, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu, 610041, China
| | - Aiping Tong
- Department of Pathology, State Key Laboratory of Biotherapy and Cancer Centre, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu, 610041, China
| | - Xiaofei Shen
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Paediatrics, Division of Neurology, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Xiaodong Sun
- Department of Pharmacology, West China School of Basic Medical Sciences and Forensic Medicine, Sichuan University, Chengdu, 610041, China
| | - Da Jia
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Paediatrics, Division of Neurology, West China Second University Hospital, Sichuan University, Chengdu, 610041, China.
| | - Qingxiang Sun
- Department of Pathology, State Key Laboratory of Biotherapy and Cancer Centre, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu, 610041, China.
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22
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Qu W, Suazo KF, Liu W, Cheng S, Jeong A, Hottman D, Yuan LL, Distefano MD, Li L. Neuronal Protein Farnesylation Regulates Hippocampal Synaptic Plasticity and Cognitive Function. Mol Neurobiol 2020; 58:1128-1144. [PMID: 33098528 DOI: 10.1007/s12035-020-02169-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 10/12/2020] [Indexed: 12/30/2022]
Abstract
Protein prenylation is a post-translational lipid modification that governs a variety of important cellular signaling pathways, including those regulating synaptic functions and cognition in the nervous system. Two enzymes, farnesyltransferase (FT) and geranylgeranyltransferase type I (GGT), are essential for the prenylation process. Genetic reduction of FT or GGT ameliorates neuropathology but only FT haplodeficiency rescues cognitive function in transgenic mice of Alzheimer's disease. A follow-up study showed that systemic or forebrain neuron-specific deficiency of GGT leads to synaptic and cognitive deficits under physiological conditions. Whether FT plays different roles in shaping neuronal functions and cognition remains elusive. This study shows that in contrast to the detrimental effects of GGT reduction, systemic haplodeficiency of FT has little to no impact on hippocampal synaptic plasticity and cognition. However, forebrain neuron-specific FT deletion also leads to reduced synaptic plasticity, memory retention, and hippocampal dendritic spine density. Furthermore, a novel prenylomic analysis identifies distinct pools of prenylated proteins that are affected in the brain of forebrain neuron-specific FT and GGT knockout mice, respectively. Taken together, this study uncovers that physiological levels of FT and GGT in neurons are essential for normal synaptic/cognitive functions and that the prenylation status of specific signaling molecules regulates neuronal functions.
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Affiliation(s)
- Wenhui Qu
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Kiall F Suazo
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Wenfeng Liu
- Department of Experimental and Clinical Pharmacology, University of Minnesota, McGuire Translational Research Facility (MTRF) 4-208, 2001 6th Street SE, Minneapolis, MN, 55455, USA
| | - Shaowu Cheng
- Department of Experimental and Clinical Pharmacology, University of Minnesota, McGuire Translational Research Facility (MTRF) 4-208, 2001 6th Street SE, Minneapolis, MN, 55455, USA
| | - Angela Jeong
- Department of Experimental and Clinical Pharmacology, University of Minnesota, McGuire Translational Research Facility (MTRF) 4-208, 2001 6th Street SE, Minneapolis, MN, 55455, USA
| | - David Hottman
- Department of Experimental and Clinical Pharmacology, University of Minnesota, McGuire Translational Research Facility (MTRF) 4-208, 2001 6th Street SE, Minneapolis, MN, 55455, USA
| | - Li-Lian Yuan
- Department of Physiology and Pharmacology, Des Moines University, Des Moines, IA, 50312, USA
| | - Mark D Distefano
- Department of Chemistry, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Ling Li
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA. .,Department of Experimental and Clinical Pharmacology, University of Minnesota, McGuire Translational Research Facility (MTRF) 4-208, 2001 6th Street SE, Minneapolis, MN, 55455, USA. .,Graduate Program in Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA.
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23
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Goncalves IL, Tal S, Barki-Harrington L, Sapir A. Conserved statin-mediated activation of the p38-MAPK pathway protects Caenorhabditis elegans from the cholesterol-independent effects of statins. Mol Metab 2020; 39:101003. [PMID: 32339771 PMCID: PMC7240216 DOI: 10.1016/j.molmet.2020.101003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/12/2020] [Accepted: 04/17/2020] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVE Statins are a group of medications that reduce cholesterol synthesis by inhibiting the activity of HMG-CoA reductase, a key enzyme in the mevalonate pathway. The clinical use of statins to lower excess cholesterol levels has revolutionized the cardiovascular field and increased the survival of millions, but some patients have adverse side effects. A growing body of data suggests that some of the beneficial and adverse effects of statins, including their anti-inflammatory, anti-tumorigenic, and myopathic activities, are cholesterol-independent. However, the underlying mechanisms for these effects of statins are not well defined. METHODS Because Caenorhabditis elegans (C. elegans) lacks the cholesterol synthesis branch of the mevalonate pathway, this organism is a powerful system to unveil the cholesterol-independent effects of statins. We used genetic and biochemical approaches in C. elegans and cultured macrophage-derived murine cells to study the cellular response to statins. RESULTS We found that statins activate a conserved p38-MAPK (p38) cascade and that the protein geranylgeranylation branch of the mevalonate pathway links the effect of statins to the activation of this p38 pathway. We propose that the blockade of geranylgeranylation impairs the function of specific small GTPases we identified as upstream regulators of the p38 pathway. Statin-mediated p38 activation in C. elegans results in the regulation of programs of innate immunity, stress, and metabolism. In agreement with this regulation, knockout of the p38 pathway results in the hypersensitivity of C. elegans to statins. Treating cultured mammalian cells with clinical doses of statins results in the activation of the same p38 pathway, which upregulates the COX-2 protein, a major regulator of innate immunity in mammals. CONCLUSIONS Statins activate an evolutionarily conserved p38 pathway to regulate metabolism and innate immunity. Our results highlight the cytoprotective role of p38 activation under statin treatment in vivo and propose that this activation underlies many of the critical cholesterol-independent effects of statins.
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Affiliation(s)
- Irina Langier Goncalves
- Department of Biology and the Environment, Faculty of Natural Sciences, University of Haifa-Oranim, Tivon, 36006 Israel
| | - Sharon Tal
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa, 3498838, Israel
| | - Liza Barki-Harrington
- Department of Human Biology, Faculty of Natural Sciences, University of Haifa, Haifa, 3498838, Israel
| | - Amir Sapir
- Department of Biology and the Environment, Faculty of Natural Sciences, University of Haifa-Oranim, Tivon, 36006 Israel.
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24
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Liu W, Chen Y, Xu W, Wang W, Tang L, Xia R, Zhu Q. Fentanyl stimulates tumor angiogenesis via activating multiple pro-angiogenic signaling pathways. Biochem Biophys Res Commun 2020; 532:225-230. [PMID: 32861420 DOI: 10.1016/j.bbrc.2020.08.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Accepted: 08/13/2020] [Indexed: 02/02/2023]
Abstract
Angiogenesis plays a vital role in tumor progression and metastasis. To better understand the role of anesthesia in tumor biology, we previously reported that bupivacaine displayed the inhibitory effects in endothelial cells. In this work, we demonstrated that fentanyl, an opioid medication commonly used in cancer patients, stimulated tumor angiogenesis. We found that fentanyl at nanomolar concentrations significantly stimulated capillary network formation of human lung tumor-associated endothelial cell (HLT-EC) in a similar manner as vascular endothelial growth factor (VEGF), and furthermore that the stimulatory effect of fentanyl was mainly involved in early stage of HLT-EC vascular structure assembly. Particularly, fentanyl significantly increased HLT-EC growth and migration. Fentanyl also protected HLT-EC from apoptosis induced by growth factor withdrawal. In contrast, the same concentrations of fentanyl did not affect human lung cancer cell growth and survival. Fentanyl stimulated migration of some but not all tested human lung cancer cells. Mechanism analysis suggested that fentanyl activates multiple pro-angiogenic signaling pathways, including VEGFR2/FAK/PI3K/Akt and small GTPases. Our work systematically demonstrates that fentanyl stimulates tumor angiogenesis via activating multiple pro-angiogenic signaling pathways. Our findings highlight the potential adverse effect of fentanyl in cancer patients.
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Affiliation(s)
- Weiwei Liu
- Department of Anesthesiology, The First Affiliated Hospital of Yangtze University, The First People's Hospital of Jingzhou, Jingzhou, Hubei Province, China
| | - Yi Chen
- Department of Anesthesiology, The First Affiliated Hospital of Yangtze University, The First People's Hospital of Jingzhou, Jingzhou, Hubei Province, China
| | - Wei Xu
- Department of Anesthesiology, The First Affiliated Hospital of Yangtze University, The First People's Hospital of Jingzhou, Jingzhou, Hubei Province, China
| | - Wei Wang
- Department of Anesthesiology, The First Affiliated Hospital of Yangtze University, The First People's Hospital of Jingzhou, Jingzhou, Hubei Province, China
| | - Li Tang
- Department of Anesthesiology, The First Affiliated Hospital of Yangtze University, The First People's Hospital of Jingzhou, Jingzhou, Hubei Province, China
| | - Rui Xia
- Department of Anesthesiology, The First Affiliated Hospital of Yangtze University, The First People's Hospital of Jingzhou, Jingzhou, Hubei Province, China.
| | - Qiong Zhu
- Department of Anesthesiology, The First Affiliated Hospital of Yangtze University, The First People's Hospital of Jingzhou, Jingzhou, Hubei Province, China.
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25
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Abstract
During development of metastasis, tumor cells migrate through different tissues and encounter different extracellular matrices. An ability of cells to adapt mechanisms of their migration to these diverse environmental conditions, called migration plasticity, gives tumor cells an advantage over normal cells for long distant dissemination. Different modes of individual cell motility-mesenchymal and amoeboid-are driven by different molecular mechanisms, which largely depend on functions of the actin cytoskeleton that can be modulated in a wide range by cellular signaling mechanisms in response to environmental conditions. Various triggers can switch one motility mode to another, but regulations of these transitions are incompletely understood. However, understanding of the mechanisms driving migration plasticity is instrumental for finding anti-cancer treatment capable to stop cancer metastasis. In this review, we discuss cytoskeletal features, which allow the individually migrating cells to switch between mesenchymal and amoeboid migrating modes, called mesenchymal-to-amoeboid transition (MAT). We briefly describe main characteristics of different cell migration modes, and then discuss the triggering factors that initiate MAT with special attention to cytoskeletal features essential for migration plasticity.
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Affiliation(s)
- Antonina Y Alexandrova
- Laboratory of Mechanisms of Carcinogenesis, N.N. Blokhin Russian Cancer Research Center, Moscow, Russia.
| | - Aleksandra S Chikina
- Cell Migration and Invasion and Spatio-Temporal Regulation of Antigen Presentation teams, UMR144/U932 Institut Curie, Paris, France
| | - Tatyana M Svitkina
- Department of Biology, University of Pennsylvania, Philadelphia, PA, United States
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26
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Leiva NL, Nolly MB, Ávila Maniero M, Losinno AD, Damiani MT. Rab Proteins: Insights into Intracellular Trafficking in Endometrium. Reprod Sci 2020; 28:12-22. [PMID: 32638281 DOI: 10.1007/s43032-020-00256-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 05/28/2020] [Accepted: 06/30/2020] [Indexed: 02/01/2023]
Abstract
Rab proteins belong to the Ras superfamily of small monomeric GTPases. These G proteins are the main controllers of vesicular transport in every tissue, among them, the endometrium. They are in charge of to the functional subcellular compartmentalization and cargo transport between organelles and the plasma membrane. In turn, intracellular trafficking contributes to endometrial changes during the menstrual cycle, secretion to the uterine fluid, and trophoblast implantation; however, few reports analyze the role of Rab proteins in the uterus. In general, Rab proteins control the release of cytokines, growth factors, enzymes, hormones, cell adhesion molecules, and mucus. Further, the secretion of multiple compounds into the uterine cavity is required for successful implantation. Therefore, alterations in Rab-controlled intracellular transport likely impair secretory processes to the uterine fluid that may correlate with abnormal endometrial development and failed reproductive outcomes. Overall, they could explain recurrent miscarriages, female infertility, and/or assisted reproductive failure. Interestingly, estrogen (E2) and progesterone (P) regulate gene expression of Rab proteins involved in secretory pathways. This review aims to gather information regarding the role of Rab proteins and intracellular trafficking in the endometrium during the different menstrual phases, and in the generation of a receptive stage for embryo implantation, modulated by E2 and P. This knowledge might be useful for the development of novel reproductive therapies that overcome low implantation rates of assisted reproductive procedures.
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Affiliation(s)
- Natalia L Leiva
- CONICET-UNCuyo-IMBECU, 5500, Mendoza, Argentina.,Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina
| | - Mariela B Nolly
- CONICET-UNCuyo-IMBECU, 5500, Mendoza, Argentina.,Facultad de Ciencias Médicas, Instituto de Bioquímica y Biotecnología, Laboratorio de Bioquímica e Inmunidad, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina
| | - Mariángeles Ávila Maniero
- Facultad de Ciencias Médicas, Instituto de Bioquímica y Biotecnología, Laboratorio de Bioquímica e Inmunidad, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina
| | - Antonella D Losinno
- Facultad de Ciencias Médicas, Instituto de Bioquímica y Biotecnología, Laboratorio de Bioquímica e Inmunidad, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina
| | - Maria Teresa Damiani
- CONICET-UNCuyo-IMBECU, 5500, Mendoza, Argentina. .,Facultad de Ciencias Médicas, Instituto de Bioquímica y Biotecnología, Laboratorio de Bioquímica e Inmunidad, Universidad Nacional de Cuyo, 5500, Mendoza, Argentina. .,Instituto de Bioquímica y Biotecnología, Facultad de Ciencias Médicas, IMBECU-CONICET-UNCuyo, Universidad Nacional de Cuyo, Centro Universitario, 5500, Mendoza, Argentina.
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27
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Li ZL, Müller-Greven J, Kim S, Tamagnone L, Buck M. Plexin-Bs enhance their GAP activity with a novel activation switch loop generating a cooperative enzyme. Cell Mol Life Sci 2020; 78:1101-1112. [PMID: 32601713 DOI: 10.1007/s00018-020-03571-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 05/24/2020] [Accepted: 06/12/2020] [Indexed: 01/01/2023]
Abstract
Plexins receive guidance cues from semaphorin ligands and transmit their signal through the plasma membrane. This family of proteins is unique amongst single-pass transmembrane receptors as their intracellular regions interact directly with several small GTPases, which regulate cytoskeletal dynamics and cell adhesion. Here, we characterize the GTPase Activating Protein (GAP) function of Plexin-B1 and find that a cooperative GAP activity towards the substrate GTPase, Rap1b, is associated with the N-terminal Juxtamembrane region of Plexin-B1. Importantly, we unveil an activation mechanism of Plexin-B1 by identifying a novel functional loop which partially blocks Rap1b entry into the plexin GAP domain. Consistent with the concept of allokairy developed for other systems, Plexin-B activity is increased by an apparent substrate-mediated cooperative effect. Simulations and mutagenesis suggest the repositioned JM conformation is stabilized by the new activation switch loop when the active site is occupied, giving rise to faster enzymatic turnover and cooperative behavior. The biological implications, essentially those of a threshold behavior for cell migration, are discussed.
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Affiliation(s)
- Zhen-Lu Li
- Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Jeannine Müller-Greven
- Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - SoonJeung Kim
- Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Luca Tamagnone
- School of Medicine, Università Cattolica del Sacro Cuore, 00168, Rome, Italy
| | - Matthias Buck
- Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
- Department of Pharmacology, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
- Department of Neurosciences, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
- Case Comprehensive Cancer Center, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH, 44106, USA.
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28
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Dejgaard SY, Presley JF. Rab18: new insights into the function of an essential protein. Cell Mol Life Sci 2019; 76:1935-1945. [PMID: 30830238 DOI: 10.1007/s00018-019-03050-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 02/14/2019] [Accepted: 02/19/2019] [Indexed: 12/14/2022]
Abstract
Rab18 is one of the small number of conserved Rab proteins which have been traced to the last eukaryotic common ancestor. It is found in organisms ranging from humans to trypanosomes, and localizes to multiple organelles, including most notably endoplasmic reticulum and lipid droplets. In humans, absence of Rab18 leads to a severe illness known as Warburg-Micro syndrome. Despite this evidence that Rab18 is essential, its role in cells remains mysterious. However, recent studies identifying effectors and interactors of Rab18, are now shedding light on its mechanism of action, suggesting functions related to organelle tethering and to autophagy. In this review, we examine the variety of roles proposed for Rab18 with a focus on new evidence giving insights into the molecular mechanisms it utilizes. Based on this summary of our current understanding, we identify priority areas for further research.
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Affiliation(s)
- Selma Yilmaz Dejgaard
- Department of Medical Biology, Near East University, Nicosia, Cyprus.,Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, QC, H3A 0C7, Canada
| | - John F Presley
- Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, QC, H3A 0C7, Canada.
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29
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Dilan T, Ramamurthy V. The Dynamic and Complex Role of the Joubert Syndrome-Associated Ciliary Protein, ADP-Ribosylation Factor-Like GTPase 13B (ARL13B) in Photoreceptor Development and Maintenance. Adv Exp Med Biol 2019; 1185:501-505. [PMID: 31884661 DOI: 10.1007/978-3-030-27378-1_82] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Photoreceptor neurons are modified primary cilia with an extended ciliary compartment known as the outer segment (OS). The mechanism behind the elaboration of photoreceptor cilia and OS morphogenesis remains poorly understood. In this review, we discuss the role of ADP-ribosylation factor-like GTPase 13B (ARL13B), a small GTPase in OS morphogenesis and its impact on photoreceptor health and biology.
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Affiliation(s)
- Tanya Dilan
- Departments of Ophthalmology, West Virginia University, Morgantown, WV, USA
| | - Visvanathan Ramamurthy
- Departments of Ophthalmology, West Virginia University, Morgantown, WV, USA.
- Departments of Biochemistry, West Virginia University, Morgantown, WV, USA.
- Eye Institute, One Medical Center Drive, West Virginia University, Morgantown, WV, USA.
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30
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Lehtonen J, Potrzebowska K, Samuelsson M, Svensson L. Integrin Dependent RhoB Activation Assay Using Leukocytes. Bio Protoc 2018; 8:e3105. [PMID: 34532550 DOI: 10.21769/bioprotoc.3105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 01/11/2018] [Accepted: 01/15/2018] [Indexed: 11/02/2022] Open
Abstract
To be able to migrate, leukocyte needs to re-use its adhesion molecules to move forward. These adhesion molecules are called integrins and are intracellularly transported via endocytosis and exocytosis in order to translocate to a new site on the cell membrane. The intracellular transportation is regulated by different small GTPases including RhoB. Here we describe an activation assay of RhoB in leukocytes migrating on ICAM-1Fc coated dishes using commercially available Rhoteikin coated agarose beads. Although this is a specific protocol for LFA-1 induced RhoB activation, it can also be used for RhoB activation induced by other soluble and insoluble factors.
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Affiliation(s)
- Janne Lehtonen
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | | | - Malin Samuelsson
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Lena Svensson
- Department of Experimental Medical Science, Lund University, Lund, Sweden.,The School of Medical Sciences, Örebro University, Örebro, Sweden
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31
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Kjos I, Vestre K, Guadagno NA, Borg Distefano M, Progida C. Rab and Arf proteins at the crossroad between membrane transport and cytoskeleton dynamics. Biochim Biophys Acta Mol Cell Res 2018; 1865:1397-1409. [PMID: 30021127 DOI: 10.1016/j.bbamcr.2018.07.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 07/05/2018] [Accepted: 07/13/2018] [Indexed: 01/04/2023]
Abstract
The intracellular movement and positioning of organelles and vesicles is mediated by the cytoskeleton and molecular motors. Small GTPases like Rab and Arf proteins are main regulators of intracellular transport by connecting membranes to cytoskeleton motors or adaptors. However, it is becoming clear that interactions between these small GTPases and the cytoskeleton are important not only for the regulation of membrane transport. In this review, we will cover our current understanding of the mechanisms underlying the connection between Rab and Arf GTPases and the cytoskeleton, with special emphasis on the double role of these interactions, not only in membrane trafficking but also in membrane and cytoskeleton remodeling. Furthermore, we will highlight the most recent findings about the fine control mechanisms of crosstalk between different members of Rab, Arf, and Rho families of small GTPases in the regulation of cytoskeleton organization.
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Affiliation(s)
- Ingrid Kjos
- Department of Biosciences, University of Oslo, Norway
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32
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Abstract
Dendritic cells (DCs) trigger CD8 + T cell responses after the internalization of exogenous antigens in a process called cross-presentation. Multiple intracellular transport events within the endocytic and secretory routes take place in order to accomplish this fundamental immunological process. The endomembrane system can be envisioned as a complex network of membrane domains coordinately working in the fusion of organelles, the budding of vesicles and tubules, and modifying the molecular composition of the limiting membranes. In this context of tightly regulated and dynamic endomembrane transport, small GTPases of the Rab family display a pivotal role by organizing membrane microdomains and defining specific identities to the different intracellular compartments. In this review, we synthesize and update the current knowledge about Rab22a, which has been involved in several immune functions. In this way, we analyze the intracellular localization of Rab22a and its important role in the endocytic recycling, including its relevance during MHC-I trafficking, antigen cross-presentation by DCs and the formation of T cell conjugates. We also describe how different pathogenic microorganisms hijack Rab22a functions to achieve efficient infection and intracellular survival strategies. Furthermore, we examine the oncogenic properties of Rab22a and how its expression determines the progression of many tumors. In summary, we highlight the role of Rab22a as a key effector of the intracellular trafficking that could be exploited in future therapies to modulate the immune system.
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Affiliation(s)
- Luis S Mayorga
- Instituto de Histología y Embriología de Mendoza (IHEM, Universidad Nacional de Cuyo, CONICET), Facultad de Ciencias Médicas and Facultad de Ciencias Exactas y Naturales, Mendoza, Argentina.
| | - Ignacio Cebrian
- Instituto de Histología y Embriología de Mendoza (IHEM, Universidad Nacional de Cuyo, CONICET), Facultad de Ciencias Médicas and Facultad de Ciencias Exactas y Naturales, Mendoza, Argentina.
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33
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Junemann J, Lämmerhirt CM, Polten F, Just I, Gerhard R, Genth H, Pich A. Quantification of small GTPase glucosylation by clostridial glucosylating toxins using multiplexed MRM analysis. Proteomics 2017; 17. [PMID: 28252257 DOI: 10.1002/pmic.201700016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/10/2017] [Accepted: 02/28/2017] [Indexed: 12/29/2022]
Abstract
Large clostridial toxins mono-O-glucosylate small GTPases of the Rho and Ras subfamily. As a result of glucosylation, the GTPases are inhibited and thereby corresponding downstream signaling pathways are disturbed. Current methods for quantifying the extent of glucosylation include sequential [14 C]glucosylation, sequential [32 P]ADP-ribosylation, and Western Blot detection of nonglucosylated GTPases, with neither method allowing the quantification of the extent of glucosylation of an individual GTPase. Here, we describe a novel MS-based multiplexed MRM assay to specifically quantify the glucosylation degree of small GTPases. This targeted proteomics approach achieves a high selectivity and reproducibility, which allows determination of the in vivo substrate pattern of glucosylating toxins. As proof of principle, GTPase glucosylation was analyzed in CaCo-2 cells treated with TcdA, and glucosylation kinetics were determined for RhoA/B, RhoC, RhoG, Ral, Rap1, Rap2, (H/K/N)Ras, and R-Ras2.
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Affiliation(s)
- Johannes Junemann
- Hannover Medical School, Institute for Toxicology, Hannover, Germany
| | | | - Felix Polten
- Hannover Medical School, Institute for Toxicology, Hannover, Germany
| | - Ingo Just
- Hannover Medical School, Institute for Toxicology, Hannover, Germany
| | - Ralf Gerhard
- Hannover Medical School, Institute for Toxicology, Hannover, Germany
| | - Harald Genth
- Hannover Medical School, Institute for Toxicology, Hannover, Germany
| | - Andreas Pich
- Hannover Medical School, Institute for Toxicology, Hannover, Germany
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34
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Cleghorn WM, Bulus N, Kook S, Gurevich VV, Zent R, Gurevich EV. Non-visual arrestins regulate the focal adhesion formation via small GTPases RhoA and Rac1 independently of GPCRs. Cell Signal 2017; 42:259-269. [PMID: 29133163 DOI: 10.1016/j.cellsig.2017.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 11/09/2017] [Accepted: 11/10/2017] [Indexed: 02/07/2023]
Abstract
Arrestins recruit a variety of signaling proteins to active phosphorylated G protein-coupled receptors in the plasma membrane and to the cytoskeleton. Loss of arrestins leads to decreased cell migration, altered cell shape, and an increase in focal adhesions. Small GTPases of the Rho family are molecular switches that regulate actin cytoskeleton and affect a variety of dynamic cellular functions including cell migration and cell morphology. Here we show that non-visual arrestins differentially regulate RhoA and Rac1 activity to promote cell spreading via actin reorganization, and focal adhesion formation via two distinct mechanisms. Arrestins regulate these small GTPases independently of G-protein-coupled receptor activation.
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Affiliation(s)
- Whitney M Cleghorn
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, United States
| | - Nada Bulus
- Department of Medicine, Vanderbilt University, Nashville, TN 37232, United States
| | - Seunghyi Kook
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, United States
| | - Vsevolod V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, United States
| | - Roy Zent
- Department of Medicine, Vanderbilt University, Nashville, TN 37232, United States; Department of Veterans Affairs Hospital, Nashville, TN, 37232, United States
| | - Eugenia V Gurevich
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, United States.
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35
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Li L, Liu H, Baxter SS, Gu N, Ji M, Zhan X. The SH3 domain distinguishes the role of I-BAR proteins IRTKS and MIM in chemotactic response to serum. Biochem Biophys Res Commun 2016; 479:787-792. [PMID: 27693783 DOI: 10.1016/j.bbrc.2016.09.131] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 09/26/2016] [Indexed: 02/03/2023]
Abstract
The family of inverse BAR (I-BAR) domain proteins participates in a range of cellular processes associated with membrane dynamics and consists of five distinct members. Three of the I-BAR proteins, including insulin receptor tyrosine kinase substrate (IRTKS), contain an SH3 domain near their C-termini. Yet, the function of the SH3 domain of IRTKS remains uncharacterized. Here we report that in contrast to MIM, which is a prototype of I-BAR proteins and does not contain an SH3 domain, IRTKS promoted serum-induced cell migration along with enhanced phosphorylation of mitogen activated kinases Erk1/2 and p38, and activation of small GTPases Rac1 and Cdc42. In addition, cells overexpressing IRTKS exhibited an increased polarity characterized by elongated cytoplasm and extensive lamellipodia at leading edges. However, a mutant with deletion of the SH3 domain attenuated both cellular motility and p38 phosphorylation but had little effect on Erk1/2 phosphorylation. Also, a chimeric mutant in which the N-terminal portion of MIM is fused with the C-terminal IRTKS, including the SH3 domain, was able to promote chemotactic response to serum and cellular polarity. In contrast, a chimeric mutant in which the N-terminal IRTKS is fused with the C-terminal MIM failed to do so. Furthermore, treatment of cells with SB203580, a selective inhibitor of p38, also neutralized the effect of IRTKS on cell migration. These data indicate that the SH3 domain distinguishes the function of IRTKS in promoting cell migration and inducing signal transduction from those of SH3-less I-BAR proteins.
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Affiliation(s)
- Lushen Li
- School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China; The Center for Vascular and Inflammatory Diseases and The Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Hongyu Liu
- China-Japan Union Hospital of Jilin University, Changchun, 130031, China
| | - Shaneen S Baxter
- The Center for Vascular and Inflammatory Diseases and The Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Ning Gu
- School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China
| | - Min Ji
- School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China.
| | - Xi Zhan
- The Center for Vascular and Inflammatory Diseases and The Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Pathology, University of Maryland School of Medicine, Baltimore, MD, USA.
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36
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van Bommel B, Mikhaylova M. Talking to the neighbours: The molecular and physiological mechanisms of clustered synaptic plasticity. Neurosci Biobehav Rev 2016; 71:352-61. [PMID: 27659124 DOI: 10.1016/j.neubiorev.2016.09.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 09/15/2016] [Accepted: 09/18/2016] [Indexed: 11/23/2022]
Abstract
Synaptic connectivity forms the basis for neuronal communication and the storage of information. Experiences and learning of new abilities can drive remodelling of this connectivity and promotes the formation of spine clusters; dendritic segments with a higher spine density. Spines located within these segments are frequently co-activated, undergo different dynamics than synapses located outside of this dendritic compartment and have, in general, a longer lifetime. Several lines of evidence have shown that chemical synapses located close to each other share or compete for intracellular signalling molecules and structural resources. This sharing and competition directly influences spine dynamics. Spines can grow, shrink, increase or decrease the surface expression of receptors, channels and adhesion molecules or remain stable and unchanged over extended periods of time. Here we summarize recent discoveries and provide a closer look at spine clustering, dendritic segment-specific signalling and potential molecular mechanisms underlying associative and heterosynaptic plasticity.
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Marei H, Carpy A, Macek B, Malliri A. Proteomic analysis of Rac1 signaling regulation by guanine nucleotide exchange factors. Cell Cycle 2016; 15:1961-74. [PMID: 27152953 PMCID: PMC4968972 DOI: 10.1080/15384101.2016.1183852] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 04/13/2016] [Accepted: 04/22/2016] [Indexed: 10/30/2022] Open
Abstract
The small GTPase Rac1 is implicated in various cellular processes that are essential for normal cell function. Deregulation of Rac1 signaling has also been linked to a number of diseases, including cancer. The diversity of Rac1 functioning in cells is mainly attributed to its ability to bind to a multitude of downstream effectors following activation by Guanine nucleotide Exchange Factors (GEFs). Despite the identification of a large number of Rac1 binding partners, factors influencing downstream specificity are poorly defined, thus hindering the detailed understanding of both Rac1's normal and pathological functions. In a recent study, we demonstrated a role for 2 Rac-specific GEFs, Tiam1 and P-Rex1, in mediating Rac1 anti- versus pro-migratory effects, respectively. Importantly, via conducting a quantitative proteomic screen, we identified distinct changes in the Rac1 interactome following activation by either GEF, indicating that these opposing effects are mediated through GEF modulation of the Rac1 interactome. Here, we present the full list of identified Rac1 interactors together with functional annotation of the differentially regulated Rac1 binding partners. In light of this data, we also provide additional insights into known and novel signaling cascades that might account for the GEF-mediated Rac1-driven cellular effects.
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Affiliation(s)
- Hadir Marei
- Cell Signaling Group, Cancer Research UK Manchester Institute, The University of Manchester, Manchester, UK
| | - Alejandro Carpy
- Proteome Center Tuebingen, Interfaculty Institute for Cell Biology, University of Tuebingen, Tuebingen, Germany
| | - Boris Macek
- Proteome Center Tuebingen, Interfaculty Institute for Cell Biology, University of Tuebingen, Tuebingen, Germany
| | - Angeliki Malliri
- Cell Signaling Group, Cancer Research UK Manchester Institute, The University of Manchester, Manchester, UK
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Jedlicka P, Deller T. Understanding the role of synaptopodin and the spine apparatus in Hebbian synaptic plasticity - New perspectives and the need for computational modeling. Neurobiol Learn Mem 2016; 138:21-30. [PMID: 27470091 DOI: 10.1016/j.nlm.2016.07.023] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 07/15/2016] [Accepted: 07/23/2016] [Indexed: 12/17/2022]
Abstract
Synaptopodin (SP) is a proline-rich actin-associated protein essential for the formation of a spine apparatus (SA) in dendritic spines. The SA consists of stacks of smooth endoplasmic reticulum (sER) contiguous with the meshwork of somatodendritic ER. Spines of SP-deficient mice contain sER but no SA, demonstrating that SP is necessary for the assembly of ER cisterns into the more complex SA organelle. Although the SA was described decades ago, its function was difficult to investigate and remained elusive, in part because reliable markers for the SA were missing. After SP was identified as an essential component and a reliable marker of the SA, a role of SP/SA in hippocampal synaptic plasticity could be firmly established using loss-of-function approaches. Further studies revealed that SP/SA participate in the regulation of Ca2+-dependent spine-specific Hebbian plasticity and in activity-dependent changes in the spine actin cytoskeleton. In this review we are summarizing recent progress made on SP/SA in Hebbian plasticity and discuss open questions such as causality, spatiotemporal dynamics and complementarity of SP/SA-dependent mechanisms. We are proposing that computational modeling of spine Ca2+-signaling and actin remodeling pathways could address some of these issues and could indicate future research directions. Moreover, reaction-diffusion simulations could help to identify key feedforward and feedback regulatory motifs regulating the switch between an LTP and an LTD signaling module in SP/SA-containing spines, thus helping to find a unified view of SP/SA action in Hebbian plasticity.
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Affiliation(s)
- Peter Jedlicka
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, D-60590 Frankfurt/Main, Germany.
| | - Thomas Deller
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University Frankfurt, D-60590 Frankfurt/Main, Germany.
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Jiménez-Sánchez A. Coevolution of RAC Small GTPases and their Regulators GEF Proteins. Evol Bioinform Online 2016; 12:121-31. [PMID: 27226705 PMCID: PMC4872645 DOI: 10.4137/ebo.s38031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 03/31/2016] [Accepted: 04/03/2016] [Indexed: 01/16/2023] Open
Abstract
RAC proteins are small GTPases involved in important cellular processes in eukaryotes, and their deregulation may contribute to cancer. Activation of RAC proteins is regulated by DOCK and DBL protein families of guanine nucleotide exchange factors (GEFs). Although DOCK and DBL proteins act as GEFs on RAC proteins, DOCK and DBL family members are evolutionarily unrelated. To understand how DBL and DOCK families perform the same function on RAC proteins despite their unrelated primary structure, phylogenetic analyses of the RAC, DBL, and DOCK families were implemented, and interaction patterns that may suggest a coevolutionary process were searched. Interestingly, while RAC and DOCK proteins are very well conserved in humans and among eukaryotes, DBL proteins are highly divergent. Moreover, correlation analyses of the phylogenetic distances of RAC and GEF proteins and covariation analyses between residues in the interacting domains showed significant coevolution rates for both RAC–DOCK and RAC–DBL interactions.
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Affiliation(s)
- Alejandro Jiménez-Sánchez
- Cancer Research UK Cambridge Institute, University of Cambridge, Li Ka Shing Centre, Cambridge, UK.; Previously at Department of Biology, University of York, York, UK
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40
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Zhang F, Cheong JK. The renewed battle against RAS-mutant cancers. Cell Mol Life Sci 2016; 73:1845-58. [PMID: 26892781 DOI: 10.1007/s00018-016-2155-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 01/28/2016] [Accepted: 02/01/2016] [Indexed: 12/13/2022]
Abstract
The RAS genes encode for members of a large superfamily of guanosine-5'-triphosphate (GTP)-binding proteins that control diverse intracellular signaling pathways to promote cell proliferation. Somatic mutations in the RAS oncogenes are the most common activating lesions found in human cancers. These mutations invariably result in the gain-of-function of RAS by impairing GTP hydrolysis and are frequently associated with poor responses to standard cancer therapies. In this review, we summarize key findings of past and present landmark studies that have deepened our understanding of the RAS biology in the context of oncogenesis. We also discuss how emerging areas of research could further bolster a renewed global effort to target the largely undruggable oncogenic RAS and/or its activated downstream effector signaling cascades to achieve better treatment outcomes for RAS-mutant cancer patients.
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Affiliation(s)
- Fuquan Zhang
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Jit Kong Cheong
- Programme in Cancer and Stem Cell Biology, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore.
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41
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Just WW, Peränen J. Small GTPases in peroxisome dynamics. Biochim Biophys Acta 2016; 1863:1006-13. [PMID: 26775587 DOI: 10.1016/j.bbamcr.2016.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 01/05/2016] [Accepted: 01/07/2016] [Indexed: 12/12/2022]
Abstract
In this review article, we summarize current knowledge on peroxisome biogenesis/functions and the role that small GTPases may play in these processes. Precise intracellular distribution of cell organelles requires their regulated association to microtubules and the actin cytoskeleton. In this respect, RhoGDP/RhoGTP favor binding of peroxisomes to microtubules and actin filaments. In its GTP-bound form, RhoA activates a regulatory cascade involving Rho kinaseII and non-muscle myosinIIA. Such interactions frequently depend on phosphoinositides (PIs) of which PI4P, PI(4,5)P2, and PI(3,5)P2 were found to be present in the peroxisomal membrane. PIs are pivotal determinants of intracellular signaling and known to regulate a wide range of cellular functions. In many of these functions, small GTPases are implicated. The small GTPase ADP-ribosylation factor 1 (Arf1), for example, is known to stimulate synthesis of PI4P and PI(4,5)P2 on the Golgi to regulate protein and lipid sorting. In vitro binding assays localized Arf1 and the COPI complex to peroxisomes. In light of the recent discussion of pre-peroxisomal vesicle generation at the ER, peroxisomal Arf1-COPI vesicles may serve retrograde transport of ER-resident components. A mass spectrometric screen localized various Rab proteins to peroxisomes. Overexpression of these proteins in combination with laser-scanning fluorescence microscopy co-localized Rab6, Rab8, Rab10, Rab14, and Rab18 with peroxisomal structures. By analogy to the role these proteins play in other organelle dynamics, we may envisage what the function of these proteins may be in relation to the peroxisomal compartment.
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Romarowski A, Battistone MA, La Spina FA, Puga Molina LDC, Luque GM, Vitale AM, Cuasnicu PS, Visconti PE, Krapf D, Buffone MG. PKA-dependent phosphorylation of LIMK1 and Cofilin is essential for mouse sperm acrosomal exocytosis. Dev Biol 2015; 405:237-49. [PMID: 26169470 DOI: 10.1016/j.ydbio.2015.07.008] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 07/01/2015] [Accepted: 07/09/2015] [Indexed: 02/06/2023]
Abstract
Mammalian sperm must acquire their fertilizing ability after a series of biochemical modifications in the female reproductive tract collectively called capacitation to undergo acrosomal exocytosis, a process that is essential for fertilization. Actin dynamics play a central role in controlling the process of exocytosis in somatic cells as well as in sperm from several mammalian species. In somatic cells, small GTPases of the Rho family are widely known as master regulators of actin dynamics. However, the role of these proteins in sperm has not been studied in detail. In the present work we characterized the participation of small GTPases of the Rho family in the signaling pathway that leads to actin polymerization during mouse sperm capacitation. We observed that most of the proteins of this signaling cascade and their effector proteins are expressed in mouse sperm. The activation of the signaling pathways of cAMP/PKA, RhoA/C and Rac1 is essential for LIMK1 activation by phosphorylation on Threonine 508. Serine 3 of Cofilin is phosphorylated by LIMK1 during capacitation in a transiently manner. Inhibition of LIMK1 by specific inhibitors (BMS-3) resulted in lower levels of actin polymerization during capacitation and a dramatic decrease in the percentage of sperm that undergo acrosomal exocytosis. Thus, we demonstrated for the first time that the master regulators of actin dynamics in somatic cells are present and active in mouse sperm. Combining the results of our present study with other results from the literature, we have proposed a working model regarding how LIMK1 and Cofilin control acrosomal exocytosis in mouse sperm.
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Affiliation(s)
- Ana Romarowski
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - María A Battistone
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Florenza A La Spina
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Lis del C Puga Molina
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Guillermina M Luque
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Alejandra M Vitale
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Patricia S Cuasnicu
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Pablo E Visconti
- Department of Veterinary and Animal Science, Paige Labs, University of Massachusets, Amherst, MA 01003, USA
| | - Darío Krapf
- Instituto de Biología Molecular y Celular de Rosario (CONICET-UNR), Rosario 2000 Argentina
| | - Mariano G Buffone
- Instituto de Biología y Medicina Experimental (IBYME), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.
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Abstract
Proteins reach the plasma membrane through the secretory pathway in which the trans Golgi network (TGN) acts as a sorting station. Transport from the TGN to the plasma membrane is maintained by a number of different pathways that act either directly or via the endosomal system. Here we show that a subset of cargoes depends on the ArfGAP2/3 Glo3 and ergosterol to maintain their proper localization at the plasma membrane. While interfering with neither ArfGAP2/3 activity nor ergosterol biosynthesis individually significantly altered plasma membrane localization of the tryptophan transporter Tat2, the general amino acid permease Gap1 and the v-SNARE Snc1, in a Δglo3 Δerg3 strain those proteins accumulated in internal endosomal structures. Export from the TGN to the plasma membrane and recycling from early endosomes appeared unaffected as the chitin synthase Chs3 that travels along these routes was localized normally. Our data indicate that a subset of proteins can reach the plasma membrane efficiently but after endocytosis becomes trapped in endosomal structures. Our study supports a role for ArfGAP2/3 in recycling from endosomes and in transport to the vacuole/lysosome.
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Affiliation(s)
- Alejandro F Estrada
- Growth & Development, Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland
| | - Gopinath Muruganandam
- Growth & Development, Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland
| | | | - Anne Spang
- Growth & Development, Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland
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Zhang CC, Li R, Jiang H, Lin S, Rogalski JC, Liu K, Kast J. Development and application of a quantitative multiplexed small GTPase activity assay using targeted proteomics. J Proteome Res 2015; 14:967-76. [PMID: 25569337 DOI: 10.1021/pr501010v] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Small GTPases are a family of key signaling molecules that are ubiquitously expressed in various types of cells. Their activity is often analyzed by western blot, which is limited by its multiplexing capability, the quality of isoform-specific antibodies, and the accuracy of quantification. To overcome these issues, a quantitative multiplexed small GTPase activity assay has been developed. Using four different binding domains, this assay allows the binding of up to 12 active small GTPase isoforms simultaneously in a single experiment. To accurately quantify the closely related small GTPase isoforms, a targeted proteomic approach, i.e., selected/multiple reaction monitoring, was developed, and its functionality and reproducibility were validated. This assay was successfully applied to human platelets and revealed time-resolved coactivation of multiple small GTPase isoforms in response to agonists and differential activation of these isoforms in response to inhibitor treatment. This widely applicable approach can be used for signaling pathway studies and inhibitor screening in many cellular systems.
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Affiliation(s)
- Cheng-Cheng Zhang
- The Biomedical Research Centre, ∥The Centre for Blood Research, University of British Columbia , Vancouver, BC V6T 1Z3, Canada
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Folly-Klan M, Sancerne B, Alix E, Roy CR, Cherfils J, Campanacci V. On the use of Legionella/Rickettsia chimeras to investigate the structure and regulation of Rickettsia effector RalF. J Struct Biol 2014; 189:98-104. [PMID: 25498244 DOI: 10.1016/j.jsb.2014.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Revised: 12/02/2014] [Accepted: 12/03/2014] [Indexed: 02/04/2023]
Abstract
A convenient strategy to interrogate the biology of regulatory proteins is to replace individual domains by an equivalent domain from a related protein of the same species or from an ortholog of another species. It is generally assumed that the overall properties of the native protein are retained in the chimera, and that functional differences reflect only the specific determinants contained in the swapped domains. Here we used this strategy to circumvent the difficulty in obtaining crystals of Rickettsia prowazekii RalF, a bacterial protein that functions as a guanine nucleotide exchange factor for eukaryotic Arf GTPases. A RalF homolog is encoded by Legionella pneumophila, in which a C-terminal capping domain auto-inhibits the catalytic Sec7 domain and localizes the protein to the Legionella-containing vacuole. The crystal structures of domain-swapped chimeras were determined and used to construct a model of Legionella RalF with a RMSD of less than 1Å with the crystal structure, which validated the use of this approach to build a model of Rickettsia RalF. In the Rickettsia RalF model, sequence differences in the capping domain that target it to specific membranes are accommodated by a shift of the entire domain with respect to the Sec7 domain. However, local sequence changes also give rise to an artifactual salt bridge in one of the chimeras, which likely explains why this chimera is recalcitrant to activation. These findings highlight the structural plasticity whereby chimeras can be engineered, but also underline that unpredictable differences can modify their biochemical responses.
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Affiliation(s)
- Marcia Folly-Klan
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Centre de Recherche de Gif, 91198 Gif-sur-Yvette, France
| | - Bastien Sancerne
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Centre de Recherche de Gif, 91198 Gif-sur-Yvette, France
| | - Eric Alix
- Yale University School of Medicine, New Haven, CT 06536, USA
| | - Craig R Roy
- Yale University School of Medicine, New Haven, CT 06536, USA
| | - Jacqueline Cherfils
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Centre de Recherche de Gif, 91198 Gif-sur-Yvette, France.
| | - Valérie Campanacci
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Centre de Recherche de Gif, 91198 Gif-sur-Yvette, France
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Díaz J, Mendoza P, Ortiz R, Díaz N, Leyton L, Stupack D, Quest AFG, Torres VA. Rab5 is required in metastatic cancer cells for Caveolin-1-enhanced Rac1 activation, migration and invasion. J Cell Sci 2014; 127:2401-6. [PMID: 24659799 DOI: 10.1242/jcs.141689] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Rab5 is a small GTPase that regulates early endosome trafficking and other cellular processes, including cell adhesion and migration. Specifically, Rab5 promotes Rac1 activation and cancer cell migration, but little is known about the upstream regulators of Rab5. We have previously shown that the scaffolding protein Caveolin-1 (CAV1) promotes Rac1 activation and migration of cancer cells. Here, we hypothesized that CAV1 stimulates Rab5 activation, leading to increased Rac1 activity and cell migration. Expression of CAV1 in B16-F10 mouse melanoma and HT-29(US) human colon adenocarcinoma cells increased the GTP loading of Rab5, whereas shRNA-mediated targeting of endogenous CAV1 in MDA-MB-231 breast cancer cells decreased Rab5-GTP levels. Accordingly, shRNA-mediated downregulation of Rab5 decreased CAV1-mediated Rac1 activation, cell migration and invasion in B16-F10 and HT-29(US) cells. Expression of CAV1 was accompanied by increased recruitment of Tiam1, a Rac1 guanine nucleotide exchange factor (GEF), to Rab5-positive early endosomes. Using the inhibitor NSC23766, Tiam1 was shown to be required for Rac1 activation and cell migration induced by CAV1 and Rab5. Mechanistically, we provide evidence implicating p85α (also known as PIK3R1), a Rab5 GTPase-activating protein (GAP), in CAV1-dependent effects, by showing that CAV1 recruits p85α, precluding p85α-mediated Rab5 inactivation and increasing cell migration. In summary, these studies identify a novel CAV1-Rab5-Rac1 signaling axis, whereby CAV1 prevents Rab5 inactivation, leading to increased Rac1 activity and enhanced tumor cell migration and invasion.
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Affiliation(s)
- Jorge Díaz
- Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Calle Sergio Livingstone 943, Santiago, Chile Center for Molecular Studies of the Cell, Faculty of Medicine, Universidad de Chile, Avenida Independencia 1027, Santiago, Chile Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Avenida Independencia 1027, Santiago, Chile
| | - Pablo Mendoza
- Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Calle Sergio Livingstone 943, Santiago, Chile
| | - Rina Ortiz
- Center for Molecular Studies of the Cell, Faculty of Medicine, Universidad de Chile, Avenida Independencia 1027, Santiago, Chile Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Avenida Independencia 1027, Santiago, Chile
| | - Natalia Díaz
- Center for Molecular Studies of the Cell, Faculty of Medicine, Universidad de Chile, Avenida Independencia 1027, Santiago, Chile Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Avenida Independencia 1027, Santiago, Chile
| | - Lisette Leyton
- Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Avenida Independencia 1027, Santiago, Chile Program of Cell and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Avenida Independencia 1027, Santiago, Chile
| | - Dwayne Stupack
- Moores UCSD Cancer Center, University of California, La Jolla, CA 92093, USA
| | - Andrew F G Quest
- Center for Molecular Studies of the Cell, Faculty of Medicine, Universidad de Chile, Avenida Independencia 1027, Santiago, Chile Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Avenida Independencia 1027, Santiago, Chile Program of Cell and Molecular Biology, Institute of Biomedical Sciences, Faculty of Medicine, Universidad de Chile, Avenida Independencia 1027, Santiago, Chile
| | - Vicente A Torres
- Institute for Research in Dental Sciences, Faculty of Dentistry, Universidad de Chile, Calle Sergio Livingstone 943, Santiago, Chile Advanced Center for Chronic Diseases (ACCDiS), Faculty of Medicine, Universidad de Chile, Avenida Independencia 1027, Santiago, Chile
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Mazhab-Jafari MT, Marshall CB, Ho J, Ishiyama N, Stambolic V, Ikura M. Structure-guided mutation of the conserved G3-box glycine in Rheb generates a constitutively activated regulator of mammalian target of rapamycin (mTOR). J Biol Chem 2014; 289:12195-201. [PMID: 24648513 DOI: 10.1074/jbc.c113.543736] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Constitutively activated variants of small GTPases, which provide valuable functional probes of their role in cellular signaling pathways, can often be generated by mutating the canonical catalytic residue (e.g. Ras Q61L) to impair GTP hydrolysis. However, this general approach is ineffective for a substantial fraction of the small GTPase family in which this residue is not conserved (e.g. Rap) or not catalytic (e.g. Rheb). Using a novel engineering approach, we have manipulated nucleotide binding through structure-guided substitutions of an ultraconserved glycine residue in the G3-box motif (DXXG). Substitution of Rheb Gly-63 with alanine impaired both intrinsic and TSC2 GTPase-activating protein (GAP)-mediated GTP hydrolysis by displacing the hydrolytic water molecule, whereas introduction of a bulkier valine side chain selectively blocked GTP binding by steric occlusion of the γ-phosphate. Rheb G63A stimulated phosphorylation of the mTORC1 substrate p70S6 kinase more strongly than wild-type, thus offering a new tool for mammalian target of rapamycin (mTOR) signaling.
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Affiliation(s)
- Mohammad T Mazhab-Jafari
- From the Campbell Family Cancer Research Institute, Princess Margaret Cancer Centre and, Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada
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Schuld NJ, Vervacke JS, Lorimer EL, Simon NC, Hauser AD, Barbieri JT, Distefano MD, Williams CL. The chaperone protein SmgGDS interacts with small GTPases entering the prenylation pathway by recognizing the last amino acid in the CAAX motif. J Biol Chem 2014; 289:6862-6876. [PMID: 24415755 PMCID: PMC3945348 DOI: 10.1074/jbc.m113.527192] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 01/09/2014] [Indexed: 12/31/2022] Open
Abstract
Ras family small GTPases localize at the plasma membrane, where they can activate oncogenic signaling pathways. Understanding the mechanisms that promote membrane localization of GTPases will aid development of new therapies to inhibit oncogenic signaling. We previously reported that SmgGDS splice variants promote prenylation and trafficking of GTPases containing a C-terminal polybasic region and demonstrated that SmgGDS-607 interacts with nonprenylated GTPases, whereas SmgGDS-558 interacts with prenylated GTPases in cells. The mechanism that SmgGDS-607 and SmgGDS-558 use to differentiate between prenylated and nonprenylated GTPases has not been characterized. Here, we provide evidence that SmgGDS-607 associates with GTPases through recognition of the last amino acid in the CAAX motif. We show that SmgGDS-607 forms more stable complexes in cells with nonprenylated GTPases that will become geranylgeranylated than with nonprenylated GTPases that will become farnesylated. These binding relationships similarly occur with nonprenylated SAAX mutants. Intriguingly, farnesyltransferase inhibitors increase the binding of WT K-Ras to SmgGDS-607, indicating that the pharmacological shunting of K-Ras into the geranylgeranylation pathway promotes K-Ras association with SmgGDS-607. Using recombinant proteins and prenylated peptides corresponding to the C-terminal sequences of K-Ras and Rap1B, we found that both SmgGDS-607 and SmgGDS-558 directly bind the GTPase C-terminal region, but the specificity of the SmgGDS splice variants for prenylated versus nonprenylated GTPases is diminished in vitro. Finally, we present structural homology models and data from functional prediction software to define both similar and unique features of SmgGDS-607 when compared with SmgGDS-558.
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Affiliation(s)
- Nathan J Schuld
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Jeffrey S Vervacke
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55414
| | - Ellen L Lorimer
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Nathan C Simon
- Department of Microbiology, Immunology, and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Andrew D Hauser
- Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Joseph T Barbieri
- Department of Microbiology, Immunology, and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - Mark D Distefano
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55414
| | - Carol L Williams
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
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49
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Ishida M, Arai SP, Ohbayashi N, Fukuda M. The GTPase-deficient Rab27A(Q78L) mutant inhibits melanosome transport in melanocytes through trapping of Rab27A effector protein Slac2-a/melanophilin in their cytosol: development of a novel melanosome-targetinG tag. J Biol Chem 2014; 289:11059-11067. [PMID: 24584932 DOI: 10.1074/jbc.m114.552281] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The small GTPase Rab27A is a crucial regulator of actin-based melanosome transport in melanocytes, and functionally defective Rab27A causes human Griscelli syndrome type 2, which is characterized by silvery hair. A GTPase-deficient, constitutively active Rab27A(Q78L) mutant has been shown to act as an inhibitor of melanosome transport and to induce perinuclear aggregation of melanosomes, but the molecular mechanism by which Rab27A(Q78L) inhibits melanosome transport remained to be determined. In this study, we attempted to identify the primary cause of the perinuclear melanosome aggregation induced by Rab27A(Q78L). The results showed that Rab27A(Q78L) is unable to localize on mature melanosomes and that its inhibitory activity on melanosome transport is completely dependent on its binding to the Rab27A effector Slac2-a/melanophilin. When we forcibly expressed Rab27A(Q78L) on mature melanosomes by using a novel melanosome-targeting tag that we developed in this study and named the MST tag, the MST-Rab27A(Q78L) fusion protein behaved in the same manner as wild-type Rab27A. It localized on mature melanosomes without inducing melanosome aggregation and restored normal peripheral melanosome distribution in Rab27A-deficient cells. These findings indicate that the GTPase activity of Rab27A is required for its melanosome localization but is not required for melanosome transport.
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Affiliation(s)
- Morié Ishida
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Saki P Arai
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Norihiko Ohbayashi
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai, Miyagi 980-8578, Japan.
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50
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Kawaguchi K, Saito K, Asami H, Ohta Y. ADP ribosylation factor 6 (Arf6) acts through FilGAP protein to down-regulate Rac protein and regulates plasma membrane blebbing. J Biol Chem 2014; 289:9675-82. [PMID: 24526684 DOI: 10.1074/jbc.m113.546051] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The small GTP-binding protein Arf6 reorganizes the actin cytoskeleton through the regulation of Rac activity. We identified FilGAP, a Rac-specific Rho GTPase-activating protein that is recruited to plasma membranes by binding to activated Arf6. FilGAP binds to Arf6 through its pleckstrin homology domain. Activated Arf6 stimulated RacGAP activity of FilGAP, and knockdown of endogenous Arf6 by siRNA suppresses FilGAP-mediated bleb formation. Mutant FilGAP lacking phosphatidylinositol 3,4,5-trisphosphate (PIP3) binding (FilGAP R39C) binds to activated Arf6 and induces bleb formation. Moreover, bleb formation induced by wild-type FilGAP occurs in the presence of phosphatidylinositol 3-kinase inhibitors, suggesting a PIP3-independent interaction between FilGAP and Arf6. We propose that FilGAP may function as a mediator of the regulation of Rac by Arf6.
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Affiliation(s)
- Kaori Kawaguchi
- From the Division of Cell Biology, Department of Biosciences, School of Science, Kitasato University, 1-15-1 Kitasato, Sagamihara, Minami-ku, Kanagawa 252-0373, Japan
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