1
|
Li M, Zhang L, Chen CW. Diverse Roles of Protein Palmitoylation in Cancer Progression, Immunity, Stemness, and Beyond. Cells 2023; 12:2209. [PMID: 37759431 PMCID: PMC10526800 DOI: 10.3390/cells12182209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/27/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Protein S-palmitoylation, a type of post-translational modification, refers to the reversible process of attachment of a fatty acyl chain-a 16-carbon palmitate acid-to the specific cysteine residues on target proteins. By adding the lipid chain to proteins, it increases the hydrophobicity of proteins and modulates protein stability, interaction with effector proteins, subcellular localization, and membrane trafficking. Palmitoylation is catalyzed by a group of zinc finger DHHC-containing proteins (ZDHHCs), whereas depalmitoylation is catalyzed by a family of acyl-protein thioesterases. Increasing numbers of oncoproteins and tumor suppressors have been identified to be palmitoylated, and palmitoylation is essential for their functions. Understanding how palmitoylation influences the function of individual proteins, the physiological roles of palmitoylation, and how dysregulated palmitoylation leads to pathological consequences are important drivers of current research in this research field. Further, due to the critical roles in modifying functions of oncoproteins and tumor suppressors, targeting palmitoylation has been used as a candidate therapeutic strategy for cancer treatment. Here, based on recent literatures, we discuss the progress of investigating roles of palmitoylation in regulating cancer progression, immune responses against cancer, and cancer stem cell properties.
Collapse
Affiliation(s)
- Mingli Li
- Department of Systems Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA;
| | - Leisi Zhang
- Department of Systems Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA;
| | - Chun-Wei Chen
- Department of Systems Biology, Beckman Research Institute, City of Hope, Duarte, CA 91010, USA;
- City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA
| |
Collapse
|
2
|
Hasan S, White NF, Tagliatela AC, Durall RT, Brown KM, McDiarmid GR, Meigs TE. Overexpressed Gα13 activates serum response factor through stoichiometric imbalance with Gβγ and mislocalization to the cytoplasm. Cell Signal 2023; 102:110534. [PMID: 36442589 DOI: 10.1016/j.cellsig.2022.110534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/21/2022] [Accepted: 11/21/2022] [Indexed: 11/26/2022]
Abstract
Gα13, a heterotrimeric G protein α subunit of the G12/13 subfamily, is an oncogenic driver in multiple cancer types. Unlike other G protein subfamilies that contribute to cancer progression via amino acid substitutions that abolish their deactivating, intrinsic GTPase activity, Gα13 rarely harbors such mutations in tumors and instead appears to stimulate aberrant cell growth via overexpression as a wildtype form. It is not known why this effect is exclusive to the G12/13 subfamily, nor has a mechanism been elucidated for overexpressed Gα13 promoting tumor progression. Using a reporter gene assay for serum response factor (SRF)-mediated transcription in HEK293 cells, we found that transiently expressed, wildtype Gα13 generates a robust SRF signal, approximately half the amplitude observed for GTPase-defective Gα13. When epitope-tagged, wildtype Gα13 was titrated upward in cells, a sharp increase in SRF stimulation was observed coincident with a "spillover" of Gα13 from membrane-associated to a soluble fraction. Overexpressing G protein β and γ subunits caused both a decrease in this signal and a shift of wildtype Gα13 back to the membranous fraction, suggesting that stoichiometric imbalance in the αβγ heterotrimer results in aberrant subcellular localization and signalling by overexpressed Gα13. We also examined the acylation requirements of wildtype Gα13 for signalling to SRF. Similar to GTPase-defective Gα13, S-palmitoylation of the wildtype α subunit was necessary for SRF activation but could be replaced functionally by an engineered site for N-terminal myristoylation. However, a key difference was observed between wildtype and GTPase-defective Gα13: whereas the latter protein lacking palmitoylation sites was rescued in its SRF signalling by either an engineered polybasic sequence or a C-terminal isoprenylation site, these motifs failed to restore signalling by wildtype, non-palmitoylated Gα13. These findings illuminate several components of the mechanism in which overexpressed, wildtype Gα13 contributes to growth and tumorigenic signalling, and reveal greater stringency in its requirements for post-translational modification in comparison to GTPase-defective Gα13.
Collapse
Affiliation(s)
- Sharmin Hasan
- Department of Biology, University of North Carolina Asheville, 220 Campus Drive, Asheville, NC 28804, USA
| | - Nicholas F White
- Department of Biology, University of North Carolina Asheville, 220 Campus Drive, Asheville, NC 28804, USA
| | - Alicia C Tagliatela
- Department of Biology, University of North Carolina Asheville, 220 Campus Drive, Asheville, NC 28804, USA
| | - R Taylor Durall
- Department of Biology, University of North Carolina Asheville, 220 Campus Drive, Asheville, NC 28804, USA
| | - Katherine M Brown
- Department of Biology, University of North Carolina Asheville, 220 Campus Drive, Asheville, NC 28804, USA
| | - Gray R McDiarmid
- Department of Biology, University of North Carolina Asheville, 220 Campus Drive, Asheville, NC 28804, USA
| | - Thomas E Meigs
- Department of Biology, University of North Carolina Asheville, 220 Campus Drive, Asheville, NC 28804, USA.
| |
Collapse
|
3
|
Morris G, Walder K, Berk M, Carvalho AF, Marx W, Bortolasci CC, Yung AR, Puri BK, Maes M. Intertwined associations between oxidative and nitrosative stress and endocannabinoid system pathways: Relevance for neuropsychiatric disorders. Prog Neuropsychopharmacol Biol Psychiatry 2022; 114:110481. [PMID: 34826557 DOI: 10.1016/j.pnpbp.2021.110481] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 10/19/2021] [Accepted: 11/21/2021] [Indexed: 12/12/2022]
Abstract
The endocannabinoid system (ECS) appears to regulate metabolic, cardiovascular, immune, gastrointestinal, lung, and reproductive system functions, as well as the central nervous system. There is also evidence that neuropsychiatric disorders are associated with ECS abnormalities as well as oxidative and nitrosative stress pathways. The goal of this mechanistic review is to investigate the mechanisms underlying the ECS's regulation of redox signalling, as well as the mechanisms by which activated oxidative and nitrosative stress pathways may impair ECS-mediated signalling. Cannabinoid receptor (CB)1 activation and upregulation of brain CB2 receptors reduce oxidative stress in the brain, resulting in less tissue damage and less neuroinflammation. Chronically high levels of oxidative stress may impair CB1 and CB2 receptor activity. CB1 activation in peripheral cells increases nitrosative stress and inducible nitric oxide (iNOS) activity, reducing mitochondrial activity. Upregulation of CB2 in the peripheral and central nervous systems may reduce iNOS, nitrosative stress, and neuroinflammation. Nitrosative stress may have an impact on CB1 and CB2-mediated signalling. Peripheral immune activation, which frequently occurs in response to nitro-oxidative stress, may result in increased expression of CB2 receptors on T and B lymphocytes, dendritic cells, and macrophages, reducing the production of inflammatory products and limiting the duration and intensity of the immune and oxidative stress response. In conclusion, high levels of oxidative and nitrosative stress may compromise or even abolish ECS-mediated redox pathway regulation. Future research in neuropsychiatric disorders like mood disorders and deficit schizophrenia should explore abnormalities in these intertwined signalling pathways.
Collapse
Affiliation(s)
- Gerwyn Morris
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia
| | - Ken Walder
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia.
| | - Michael Berk
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia; Orygen, Parkville, Victoria, Australia; Centre for Youth Mental Health, The University of Melbourne, Parkville, Victoria, Australia.
| | - Andre F Carvalho
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia
| | - Wolf Marx
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia.
| | - Chiara C Bortolasci
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia.
| | - Alison R Yung
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia; Orygen, Parkville, Victoria, Australia; Centre for Youth Mental Health, The University of Melbourne, Parkville, Victoria, Australia; School of Health Science, University of Manchester, UK.
| | - Basant K Puri
- University of Winchester, UK, and C.A.R., Cambridge, UK.
| | - Michael Maes
- Deakin University, IMPACT - the Institute for Mental and Physical Health and Clinical Translation, School of Medicine, Barwon Health, Geelong, Australia; Department of Psychiatry, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Bangkok, Thailand; Department of Psychiatry, Medical University of Plovdiv, Plovdiv, Bulgaria.
| |
Collapse
|
4
|
Abid HA, Inoue A, Gorvin CM. Heterogeneity of G protein activation by the calcium-sensing receptor. J Mol Endocrinol 2021; 67:41-53. [PMID: 34077389 PMCID: PMC8240730 DOI: 10.1530/jme-21-0058] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/02/2021] [Indexed: 12/20/2022]
Abstract
The calcium-sensing receptor (CaSR) is a G protein-coupled receptor that plays a fundamental role in extracellular calcium (Ca2+e) homeostasis by regulating parathyroid hormone release and urinary calcium excretion. The CaSR has been described to activate all four G protein subfamilies (Gαq/11, Gαi/o, Gα12/13, Gαs), and mutations in the receptor that cause hyper/hypocalcaemia, have been described to bias receptor signalling. However, many of these studies are based on measurements of second messengers or gene transcription that occurs many steps downstream of receptor activation and can represent convergence points of several signalling pathways. Therefore, to assess CaSR-mediated G protein activation directly, we took advantage of a recently described NanoBiT G protein dissociation assay system. Our studies, performed in HEK293 cells stably expressing CaSR, demonstrate that Ca2+e stimulation activates all Gαq/11 family and several Gαi/o family proteins, although Gαz was not activated. CaSR stimulated dissociation of Gα12/13 and Gαs from Gβ-subunits, but this occurred at a slower rate than that of other Gα-subunits. Investigation of cDNA expression of G proteins in three tissues abundantly expressing CaSR, the parathyroids, kidneys and pancreas, showed Gα11, Gαz, Gαi1 and Gα13 genes were highly expressed in parathyroid tissue, indicating CaSR most likely activates Gα11 and Gαi1 in parathyroids. In kidney and pancreas, the majority of G proteins were similarly expressed, suggesting CaSR may activate multiple G proteins in these cells. Thus, these studies validate a single assay system that can be used to robustly assess CaSR variants and biased signalling and could be utilised in the development of new pharmacological compounds targeting CaSR.
Collapse
Affiliation(s)
- Hasnat Ali Abid
- Institute of Metabolism and Systems Research and Centre for Endocrinology, Diabetes and Metabolism, University of Birmingham, Birmingham, UK
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan
| | - Caroline M Gorvin
- Institute of Metabolism and Systems Research and Centre for Endocrinology, Diabetes and Metabolism, University of Birmingham, Birmingham, UK
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, UK
- Correspondence should be addressed to C M Gorvin:
| |
Collapse
|
5
|
GNA13 regulates BCL2 expression and the sensitivity of GCB-DLBCL cells to BCL2 inhibitors in a palmitoylation-dependent manner. Cell Death Dis 2021; 12:54. [PMID: 33423045 PMCID: PMC7797003 DOI: 10.1038/s41419-020-03311-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 11/25/2020] [Accepted: 11/30/2020] [Indexed: 12/14/2022]
Abstract
GNA13, encoding one of the G protein alpha subunits of heterotrimeric G proteins that transduce signals of G protein-coupled receptors (GPCR), is frequently mutated in germinal center B-cell-like diffuse large B-cell lymphoma (GCB-DLBCL) with poor prognostic outcomes. Due to the "undruggable" nature of GNA13, targeted therapy for these patients is not available. In this study, we found that palmitoylation of GNA13 not only regulates its plasma membrane localization, but also regulates GNA13's stability. It is essential for the tumor suppressor function of GNA13 in GCB-DLBCL cells. Interestingly, GNA13 negatively regulates BCL2 expression in GCB-DLBCL cells in a palmitoylation-dependent manner. Consistently, BCL2 inhibitors were found to be effective in killing GNA13-deficient GCB-DLBCL cells in a cell-based chemical screen. Furthermore, we demonstrate that inactivating GNA13 by targeting its palmitoylation enhanced the sensitivity of GCB-DLBCL to the BCL2 inhibitor. These studies indicate that the loss-of-function mutation of GNA13 is a biomarker for BCL2 inhibitor therapy of GCB-DLBCL and that GNA13 palmitoylation is a potential target for combination therapy with BCL2 inhibitors to treat GCB-DLBCL with wild-type GNA13.
Collapse
|
6
|
Yang YM, Kuen DS, Chung Y, Kurose H, Kim SG. Gα 12/13 signaling in metabolic diseases. Exp Mol Med 2020; 52:896-910. [PMID: 32576930 PMCID: PMC7338450 DOI: 10.1038/s12276-020-0454-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 05/04/2020] [Accepted: 05/11/2020] [Indexed: 12/12/2022] Open
Abstract
As the key governors of diverse physiological processes, G protein-coupled receptors (GPCRs) have drawn attention as primary targets for several diseases, including diabetes and cardiovascular disease. Heterotrimeric G proteins converge signals from ~800 members of the GPCR family. Among the members of the G protein α family, the Gα12 family members comprising Gα12 and Gα13 have been referred to as gep oncogenes. Gα12/13 levels are altered in metabolic organs, including the liver and muscles, in metabolic diseases. The roles of Gα12/13 in metabolic diseases have been investigated. In this review, we highlight findings demonstrating Gα12/13 amplifying or dampening regulators of phenotype changes. We discuss the molecular basis of G protein biology in the context of posttranslational modifications to heterotrimeric G proteins and the cell signaling axis. We also highlight findings providing insights into the organ-specific, metabolic and pathological roles of G proteins in changes associated with specific cells, energy homeostasis, glucose metabolism, liver fibrosis and the immune and cardiovascular systems. This review summarizes the currently available knowledge on the importance of Gα12/13 in the physiology and pathogenesis of metabolic diseases, which is presented according to the basic understanding of their metabolic actions and underlying cellular and molecular bases. Understanding the activities of two members of a vital category of proteins called G proteins, which initiate metabolic changes when signaling molecules bind to cells, could lead to new therapies for many diseases. Researchers in South Korea and Japan, led by Sang Geon Kim at Seoul National University, review the significance of the Gα12 and Gα13 proteins in diseases characterised by significant changes in metabolism, including liver conditions and disorders of the cardiovascular and immune systems. Specific roles for the proteins have been identified by a variety of methods, including studying the effect of disabling the genes that code for them in mice. Recent insights suggest that drugs interfering with the activity of these Gα proteins might help treat many conditions in which the molecular signalling networks involving the proteins are disrupted.
Collapse
Affiliation(s)
- Yoon Mee Yang
- College of Pharmacy, Kangwon National University, Chuncheon, 24341, South Korea
| | - Da-Sol Kuen
- College of Pharmacy, Seoul National University, Seoul, 08826, South Korea
| | - Yeonseok Chung
- College of Pharmacy, Seoul National University, Seoul, 08826, South Korea
| | - Hitoshi Kurose
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Sang Geon Kim
- College of Pharmacy, Seoul National University, Seoul, 08826, South Korea.
| |
Collapse
|
7
|
Stecky RC, Quick CR, Fleming TL, Mull ML, Vinson VK, Whitley MS, Dover EN, Meigs TE. Divergent C-terminal motifs in Gα12 and Gα13 provide distinct mechanisms of effector binding and SRF activation. Cell Signal 2020; 72:109653. [PMID: 32330601 DOI: 10.1016/j.cellsig.2020.109653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 04/19/2020] [Accepted: 04/19/2020] [Indexed: 11/18/2022]
Abstract
The G12/13 subfamily of heterotrimeric guanine nucleotide binding proteins comprises the α subunits Gα12 and Gα13, which transduce signals for cell growth, cytoskeletal rearrangements, and oncogenic transformation. In an increasing range of cancers, overexpressed Gα12 or Gα13 are implicated in aberrant cell proliferation and/or metastatic invasion. Although Gα12 and Gα13 bind non-redundant sets of effector proteins and participate in unique signalling pathways, the structural features responsible for functional differences between these α subunits are largely unknown. Invertebrates encode a single G12/13 homolog that participates in cytoskeletal changes yet appears to lack signalling to SRF (serum response factor), a transcriptional activator stimulated by mammalian Gα12 and Gα13 to promote growth and tumorigenesis. Our previous studies identified an evolutionarily divergent region in Gα12 for which replacement by homologous sequence from Drosophila melanogaster abolished SRF signalling, whereas the same invertebrate substitution was fully tolerated in Gα13 [Montgomery et al. (2014) Mol. Pharmacol. 85: 586]. These findings prompted our current approach of evolution-guided mutagenesis to identify fine structural features of Gα12 and Gα13 that underlie their respective SRF activation mechanisms. Our results identified two motifs flanking the α4 helix that play a key role in Gα12 signalling to SRF. We found the region encompassing these motifs to provide an interacting surface for multiple Gα12-specific target proteins that fail to bind Gα13. Adjacent to this divergent region, a highly-conserved domain was vital for SRF activation by both Gα12 and Gα13. However, dissection of this domain using invertebrate substitutions revealed different signalling mechanisms in these α subunits and identified Gα13-specific determinants of binding Rho-specific guanine nucleotide exchange factors. Furthermore, invertebrate substitutions in the C-terminal, α5 helical region were selectively disruptive to Gα12 signalling. Taken together, our results identify key structural features near the C-terminus that evolved after the divergence of Gα12 and Gα13, and should aid the development of agents to selectively manipulate signalling by individual α subunits of the G12/13 subfamily.
Collapse
Affiliation(s)
- Rebecca C Stecky
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - Courtney R Quick
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - Todd L Fleming
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - Makenzy L Mull
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - Vanessa K Vinson
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - Megan S Whitley
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - E Nicole Dover
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - Thomas E Meigs
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America.
| |
Collapse
|
8
|
Tutunea-Fatan E, Lee JC, Denker BM, Gunaratnam L. Heterotrimeric Gα 12/13 proteins in kidney injury and disease. Am J Physiol Renal Physiol 2020; 318:F660-F672. [PMID: 31984793 DOI: 10.1152/ajprenal.00453.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Gα12 and Gα13 are ubiquitous members of the heterotrimeric guanine nucleotide-binding protein (G protein) family that play central and integrative roles in the regulation of signal transduction cascades within various cell types in the kidney. Gα12/Gα13 proteins enable the kidney to adapt to an ever-changing environment by transducing stimuli from cell surface receptors and accessory proteins to effector systems. Therefore, perturbations in Gα12/Gα13 levels or their activity can contribute to the pathogenesis of various renal diseases, including renal cancer. This review will highlight and discuss the complex and expanding roles of Gα12/Gα13 proteins on distinct renal pathologies, with emphasis on more recently reported findings. Deciphering how the different Gα12/Gα13 interaction networks participate in the onset and development of renal diseases may lead to the discovery of new therapeutic strategies.
Collapse
Affiliation(s)
- Elena Tutunea-Fatan
- Matthew Mailing Centre for Translational Transplant Studies, Lawson Health Research Institute, London, Ontario, Canada
| | - Jasper C Lee
- Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada
| | - Bradley M Denker
- Beth Israel Deaconess Medical Center and Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Lakshman Gunaratnam
- Matthew Mailing Centre for Translational Transplant Studies, Lawson Health Research Institute, London, Ontario, Canada.,Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada.,Division of Nephrology, Department of Medicine, University of Western Ontario, London, Ontario, Canada
| |
Collapse
|
9
|
Effects of Post-translational Modifications on Membrane Localization and Signaling of Prostanoid GPCR-G Protein Complexes and the Role of Hypoxia. J Membr Biol 2019; 252:509-526. [PMID: 31485700 DOI: 10.1007/s00232-019-00091-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 08/17/2019] [Indexed: 02/07/2023]
Abstract
G protein-coupled receptors (GPCRs) play a pivotal role in the adaptive responses to cellular stresses such as hypoxia. In addition to influencing cellular gene expression profiles, hypoxic microenvironments can perturb membrane protein localization, altering GPCR effector scaffolding and altering downstream signaling. Studies using proteomics approaches have revealed significant regulation of GPCR and G proteins by their state of post-translational modification. The aim of this review is to examine the effects of post-translational modifications on membrane localization and signaling of GPCR-G protein complexes, with an emphasis on vascular prostanoid receptors, and to highlight what is known about the effect of cellular hypoxia on these mechanisms. Understanding post-translational modifications of protein targets will help to define GPCR targets in treatment of disease, and to inform research into mechanisms of hypoxic cellular responses.
Collapse
|
10
|
Jiang H, Zhang X, Chen X, Aramsangtienchai P, Tong Z, Lin H. Protein Lipidation: Occurrence, Mechanisms, Biological Functions, and Enabling Technologies. Chem Rev 2018; 118:919-988. [PMID: 29292991 DOI: 10.1021/acs.chemrev.6b00750] [Citation(s) in RCA: 283] [Impact Index Per Article: 47.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Protein lipidation, including cysteine prenylation, N-terminal glycine myristoylation, cysteine palmitoylation, and serine and lysine fatty acylation, occurs in many proteins in eukaryotic cells and regulates numerous biological pathways, such as membrane trafficking, protein secretion, signal transduction, and apoptosis. We provide a comprehensive review of protein lipidation, including descriptions of proteins known to be modified and the functions of the modifications, the enzymes that control them, and the tools and technologies developed to study them. We also highlight key questions about protein lipidation that remain to be answered, the challenges associated with answering such questions, and possible solutions to overcome these challenges.
Collapse
Affiliation(s)
- Hong Jiang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Xiaoyu Zhang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Xiao Chen
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Pornpun Aramsangtienchai
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Zhen Tong
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| | - Hening Lin
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Cornell University , Ithaca, New York 14853, United States
| |
Collapse
|
11
|
Abstract
AKAP-Lbc is a Rho-activating guanine nucleotide exchange factor (RhoGEF) important in heart development and pro-fibrotic signaling in cardiomyocytes. Heterotrimeric G proteins of the G12/13 subfamily, comprising Gα12 and Gα13, are well characterized as stimulating a specialized group of RhoGEFs through interaction with their RGS-homology (RH) domain. Despite lacking an RH domain, AKAP-Lbc is bound by Gα12 through an unknown mechanism to activate Rho signaling. We identified a Gα12-binding region near the C-terminus of AKAP-Lbc, closely homologous to a region of p114RhoGEF that we also discovered to interact with Gα12. This binding mechanism is distinct from the well-studied interface between RH-RhoGEFs and G12/13 α subunits, as demonstrated by Gα12 mutants selectively impaired in binding either this AKAP-Lbc/p114RhoGEF region or RH-RhoGEFs. AKAP-Lbc and p114RhoGEF showed high specificity for binding Gα12 in comparison to Gα13, and experiments using chimeric G12/13 α subunits mapped determinants of this selectivity to the N-terminal region of Gα12. In cultured cells expressing constitutively GDP-bound Gα12 or Gα13, the Gα12 construct was more potent in exerting a dominant-negative effect on serum-mediated signaling to p114RhoGEF, demonstrating coupling of these signaling proteins in a cellular pathway. In addition, charge-reversal of conserved residues in AKAP-Lbc and p114RhoGEF disrupted Gα12 binding for both proteins, suggesting they harbor a common structural mechanism for interaction with this α subunit. Our results provide the first evidence of p114RhoGEF as a Gα12 signaling effector, and define a novel region conserved between AKAP-Lbc and p114RhoGEF that allows Gα12 signaling input to these non-RH RhoGEFs.
Collapse
|
12
|
Arthofer E, Hot B, Petersen J, Strakova K, Jäger S, Grundmann M, Kostenis E, Gutkind JS, Schulte G. WNT Stimulation Dissociates a Frizzled 4 Inactive-State Complex with Gα12/13. Mol Pharmacol 2016; 90:447-59. [PMID: 27458145 DOI: 10.1124/mol.116.104919] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 07/20/2016] [Indexed: 12/29/2022] Open
Abstract
Frizzleds (FZDs) are unconventional G protein-coupled receptors that belong to the class Frizzled. They are bound and activated by the Wingless/Int-1 lipoglycoprotein (WNT) family of secreted lipoglycoproteins. To date, mechanisms of signal initiation and FZD-G protein coupling remain poorly understood. Previously, we showed that FZD6 assembles with Gαi1/Gαq (but not with Gαs, Gαo and Ga12/13), and that these inactive-state complexes are dissociated by WNTs and regulated by the phosphoprotein Dishevelled (DVL). Here, we investigated the inactive-state assembly of heterotrimeric G proteins with FZD4, a receptor important in retinal vascular development and frequently mutated in Norrie disease or familial exudative vitreoretinopathy. Live-cell imaging experiments using fluorescence recovery after photobleaching show that human FZD4 assembles-in a DVL-independent manner-with Gα12/13 but not representatives of other heterotrimeric G protein subfamilies, such as Gαi1, Gαo, Gαs, and Gαq The FZD4-G protein complex dissociates upon stimulation with WNT-3A, WNT-5A, WNT-7A, and WNT-10B. In addition, WNT-induced dynamic mass redistribution changes in untransfected and, even more so, in FZD4 green fluorescent protein-transfected cells depend on Gα12/13 Furthermore, expression of FZD4 and Gα12 or Gα13 in human embryonic kidney 293 cells induces WNT-dependent membrane recruitment of p115-RHOGEF (RHO guanine nucleotide exchange factor, molecular weight 115 kDa), a direct target of Gα12/13 signaling, underlining the functionality of an FZD4-Gα12/13-RHO signaling axis. In summary, Gα12/13-mediated WNT/FZD4 signaling through p115-RHOGEF offers an intriguing and previously unappreciated mechanistic link of FZD4 signaling to cytoskeletal rearrangements and RHO signaling with implications for the regulation of angiogenesis during embryonic and tumor development.
Collapse
Affiliation(s)
- Elisa Arthofer
- Section of Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (E.A., B.H., J.P., K.S., S.J., G.S.); Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (E.A.); Faculty of Science, Institute of Experimental Biology, Masaryk University, Brno, Czech Republic (K.S., G.S.); Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany (M.G., E.K.); Department of Pharmacology, Moores Cancer Center, University of California, San Diego, La Jolla, California (J.S.G.)
| | - Belma Hot
- Section of Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (E.A., B.H., J.P., K.S., S.J., G.S.); Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (E.A.); Faculty of Science, Institute of Experimental Biology, Masaryk University, Brno, Czech Republic (K.S., G.S.); Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany (M.G., E.K.); Department of Pharmacology, Moores Cancer Center, University of California, San Diego, La Jolla, California (J.S.G.)
| | - Julian Petersen
- Section of Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (E.A., B.H., J.P., K.S., S.J., G.S.); Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (E.A.); Faculty of Science, Institute of Experimental Biology, Masaryk University, Brno, Czech Republic (K.S., G.S.); Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany (M.G., E.K.); Department of Pharmacology, Moores Cancer Center, University of California, San Diego, La Jolla, California (J.S.G.)
| | - Katerina Strakova
- Section of Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (E.A., B.H., J.P., K.S., S.J., G.S.); Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (E.A.); Faculty of Science, Institute of Experimental Biology, Masaryk University, Brno, Czech Republic (K.S., G.S.); Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany (M.G., E.K.); Department of Pharmacology, Moores Cancer Center, University of California, San Diego, La Jolla, California (J.S.G.)
| | - Stefan Jäger
- Section of Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (E.A., B.H., J.P., K.S., S.J., G.S.); Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (E.A.); Faculty of Science, Institute of Experimental Biology, Masaryk University, Brno, Czech Republic (K.S., G.S.); Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany (M.G., E.K.); Department of Pharmacology, Moores Cancer Center, University of California, San Diego, La Jolla, California (J.S.G.)
| | - Manuel Grundmann
- Section of Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (E.A., B.H., J.P., K.S., S.J., G.S.); Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (E.A.); Faculty of Science, Institute of Experimental Biology, Masaryk University, Brno, Czech Republic (K.S., G.S.); Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany (M.G., E.K.); Department of Pharmacology, Moores Cancer Center, University of California, San Diego, La Jolla, California (J.S.G.)
| | - Evi Kostenis
- Section of Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (E.A., B.H., J.P., K.S., S.J., G.S.); Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (E.A.); Faculty of Science, Institute of Experimental Biology, Masaryk University, Brno, Czech Republic (K.S., G.S.); Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany (M.G., E.K.); Department of Pharmacology, Moores Cancer Center, University of California, San Diego, La Jolla, California (J.S.G.)
| | - J Silvio Gutkind
- Section of Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (E.A., B.H., J.P., K.S., S.J., G.S.); Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (E.A.); Faculty of Science, Institute of Experimental Biology, Masaryk University, Brno, Czech Republic (K.S., G.S.); Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany (M.G., E.K.); Department of Pharmacology, Moores Cancer Center, University of California, San Diego, La Jolla, California (J.S.G.)
| | - Gunnar Schulte
- Section of Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (E.A., B.H., J.P., K.S., S.J., G.S.); Section on Molecular Signal Transduction, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (E.A.); Faculty of Science, Institute of Experimental Biology, Masaryk University, Brno, Czech Republic (K.S., G.S.); Molecular, Cellular and Pharmacobiology Section, Institute for Pharmaceutical Biology, University of Bonn, Bonn, Germany (M.G., E.K.); Department of Pharmacology, Moores Cancer Center, University of California, San Diego, La Jolla, California (J.S.G.)
| |
Collapse
|
13
|
Castañeda P, Muñoz M, García-Rojo G, Ulloa JL, Bravo JA, Márquez R, García-Pérez MA, Arancibia D, Araneda K, Rojas PS, Mondaca-Ruff D, Díaz-Véliz G, Mora S, Aliaga E, Fiedler JL. Association of N-cadherin levels and downstream effectors of Rho GTPases with dendritic spine loss induced by chronic stress in rat hippocampal neurons. J Neurosci Res 2015; 93:1476-91. [PMID: 26010004 DOI: 10.1002/jnr.23602] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 05/03/2015] [Accepted: 05/04/2015] [Indexed: 12/24/2022]
Abstract
Chronic stress promotes cognitive impairment and dendritic spine loss in hippocampal neurons. In this animal model of depression, spine loss probably involves a weakening of the interaction between pre- and postsynaptic cell adhesion molecules, such as N-cadherin, followed by disruption of the cytoskeleton. N-cadherin, in concert with catenin, stabilizes the cytoskeleton through Rho-family GTPases. Via their effector LIM kinase (LIMK), RhoA and ras-related C3 botulinum toxin substrate 1 (RAC) GTPases phosphorylate and inhibit cofilin, an actin-depolymerizing molecule, favoring spine growth. Additionally, RhoA, through Rho kinase (ROCK), inactivates myosin phosphatase through phosphorylation of the myosin-binding subunit (MYPT1), producing actomyosin contraction and probable spine loss. Some micro-RNAs negatively control the translation of specific mRNAs involved in Rho GTPase signaling. For example, miR-138 indirectly activates RhoA, and miR-134 reduces LIMK1 levels, resulting in spine shrinkage; in contrast, miR-132 activates RAC1, promoting spine formation. We evaluated whether N-cadherin/β-catenin and Rho signaling is sensitive to chronic restraint stress. Stressed rats exhibit anhedonia, impaired associative learning, and immobility in the forced swim test and reduction in N-cadherin levels but not β-catenin in the hippocampus. We observed a reduction in spine number in the apical dendrites of CA1 pyramidal neurons, with no effect on the levels of miR-132 or miR-134. Although the stress did not modify the RAC-LIMK-cofilin signaling pathway, we observed increased phospho-MYPT1 levels, probably mediated by RhoA-ROCK activation. Furthermore, chronic stress raises the levels of miR-138 in accordance with the observed activation of the RhoA-ROCK pathway. Our findings suggest that a dysregulation of RhoA-ROCK activity by chronic stress could potentially underlie spine loss in hippocampal neurons.
Collapse
Affiliation(s)
- Patricia Castañeda
- Department of Biology, Faculty of Sciences, Universidad Metropolitana de Ciencias de la Educación, Santiago, Chile
| | - Mauricio Muñoz
- Laboratory of Neuroplasticity and Neurogenetics, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| | - Gonzalo García-Rojo
- Laboratory of Neuroplasticity and Neurogenetics, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| | - José L Ulloa
- Laboratory of Neuroplasticity and Neurogenetics, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| | - Javier A Bravo
- Grupo de NeuroGastroBioquímica, Laboratorio de Química Biológica, Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Ruth Márquez
- Laboratory of Neuroplasticity and Neurogenetics, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| | - M Alexandra García-Pérez
- Laboratory of Neuroplasticity and Neurogenetics, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| | - Damaris Arancibia
- Laboratory of Neuroplasticity and Neurogenetics, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| | - Karina Araneda
- Laboratory of Neuroplasticity and Neurogenetics, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| | - Paulina S Rojas
- Laboratory of Neuroplasticity and Neurogenetics, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| | - David Mondaca-Ruff
- Graduate Student PhD Program, Department of Pharmacology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| | - Gabriela Díaz-Véliz
- Laboratorio Farmacología del Comportamiento, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Sergio Mora
- Laboratorio Farmacología del Comportamiento, ICBM, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Esteban Aliaga
- Escuela de Kinesiología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
| | - Jenny L Fiedler
- Laboratory of Neuroplasticity and Neurogenetics, Department of Biochemistry and Molecular Biology, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Santiago, Chile
| |
Collapse
|
14
|
Álvarez-Pérez B, Homs J, Bosch-Mola M, Puig T, Reina F, Verdú E, Boadas-Vaello P. Epigallocatechin-3-gallate treatment reduces thermal hyperalgesia after spinal cord injury by down-regulating RhoA expression in mice. Eur J Pain 2015; 20:341-52. [DOI: 10.1002/ejp.722] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2015] [Indexed: 12/30/2022]
Affiliation(s)
- B. Álvarez-Pérez
- Research Group of Clinical Anatomy; Embryology; Neuroscience and Molecular Oncology (NEOMA); Department of Medical Sciences; Universitat de Girona; Spain
| | - J. Homs
- Research Group of Clinical Anatomy; Embryology; Neuroscience and Molecular Oncology (NEOMA); Department of Medical Sciences; Universitat de Girona; Spain
- Department of Physical Therapy; EUSES - Universitat de Girona; Spain
| | - M. Bosch-Mola
- Research Group of Clinical Anatomy; Embryology; Neuroscience and Molecular Oncology (NEOMA); Department of Medical Sciences; Universitat de Girona; Spain
| | - T. Puig
- Research Group of Clinical Anatomy; Embryology; Neuroscience and Molecular Oncology (NEOMA); Department of Medical Sciences; Universitat de Girona; Spain
| | - F. Reina
- Research Group of Clinical Anatomy; Embryology; Neuroscience and Molecular Oncology (NEOMA); Department of Medical Sciences; Universitat de Girona; Spain
| | - E. Verdú
- Research Group of Clinical Anatomy; Embryology; Neuroscience and Molecular Oncology (NEOMA); Department of Medical Sciences; Universitat de Girona; Spain
| | - P. Boadas-Vaello
- Research Group of Clinical Anatomy; Embryology; Neuroscience and Molecular Oncology (NEOMA); Department of Medical Sciences; Universitat de Girona; Spain
| |
Collapse
|
15
|
Bicker S, Lackinger M, Weiß K, Schratt G. MicroRNA-132, -134, and -138: a microRNA troika rules in neuronal dendrites. Cell Mol Life Sci 2014; 71:3987-4005. [PMID: 25008044 PMCID: PMC11113804 DOI: 10.1007/s00018-014-1671-7] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 06/11/2014] [Accepted: 06/20/2014] [Indexed: 01/19/2023]
Abstract
Dendritic mRNA transport and local translation in the postsynaptic compartment play an important role in synaptic plasticity, learning and memory. Local protein synthesis at the synapse has to be precisely orchestrated by a plethora of factors including RNA binding proteins as well as microRNAs, an extensive class of small non-coding RNAs. By binding to complementary sequences in target mRNAs, microRNAs fine-tune protein synthesis and thereby represent critical regulators of gene expression at the post-transcriptional level. Research over the last years identified an entire network of dendritic microRNAs that fulfills an essential role in synapse development and physiology. Recent studies provide evidence that these small regulatory molecules are highly regulated themselves, at the level of expression as well as function. The importance of microRNAs for correct function of the nervous system is reflected by an increasing number of studies linking dysregulation of microRNA pathways to neurological disorders. By focusing on three extensively studied examples (miR-132, miR-134, miR-138), this review will attempt to illustrate the complex regulatory roles of dendritic microRNAs at the synapse and their implications for pathological conditions.
Collapse
Affiliation(s)
- Silvia Bicker
- Biochemical-Pharmacological Center (BPC) Marburg, Institute of Physiological Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Martin Lackinger
- Biochemical-Pharmacological Center (BPC) Marburg, Institute of Physiological Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Kerstin Weiß
- Biochemical-Pharmacological Center (BPC) Marburg, Institute of Physiological Chemistry, Philipps-University Marburg, Marburg, Germany
| | - Gerhard Schratt
- Biochemical-Pharmacological Center (BPC) Marburg, Institute of Physiological Chemistry, Philipps-University Marburg, Marburg, Germany
| |
Collapse
|
16
|
The predictive value of 53BP1 and BRCA1 mRNA expression in advanced non-small-cell lung cancer patients treated with first-line platinum-based chemotherapy. Oncotarget 2014; 4:1572-81. [PMID: 24197907 PMCID: PMC3858546 DOI: 10.18632/oncotarget.1157] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Platinum-based chemotherapy is the standard first-line treatment for non-oncogene-addicted non-small cell lung cancers (NSCLCs) and the analysis of multiple DNA repair genes could improve current models for predicting chemosensitivity. We investigated the potential predictive role of components of the 53BP1 pathway in conjunction with BRCA1. The mRNA expression of BRCA1, MDC1, CASPASE3, UBC13, RNF8, 53BP1, PIAS4, UBC9 and MMSET was analyzed by real-time PCR in 115 advanced NSCLC patients treated with first-line platinum-based chemotherapy. Patients expressing low levels of both BRCA1 and 53BP1 obtained a median progression-free survival of 10.3 months and overall survival of 19.3 months, while among those with low BRCA1 and high 53BP1 progression-free survival was 5.9 months (P <0.0001) and overall survival was 8.2 months (P=0.001). The expression of 53BP1 refines BRCA1-based predictive modeling to identify patients most likely to benefit from platinum-based chemotherapy.
Collapse
|
17
|
Carter AM, Gutowski S, Sternweis PC. Regulated localization is sufficient for hormonal control of regulator of G protein signaling homology Rho guanine nucleotide exchange factors (RH-RhoGEFs). J Biol Chem 2014; 289:19737-46. [PMID: 24855647 DOI: 10.1074/jbc.m114.564930] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The regulator of G protein signaling homology (RH) Rho guanine nucleotide exchange factors (RhoGEFs) (p115RhoGEF, leukemia-associated RhoGEF, and PDZ-RhoGEF) contain an RH domain and are specific GEFs for the monomeric GTPase RhoA. The RH domains interact specifically with the α subunits of G12 heterotrimeric GTPases. Activated Gα13 modestly stimulates the exchange activity of both p115RhoGEF and leukemia-associated RhoGEF but not PDZ-RhoGEF. Because all three RH-RhoGEFs can localize to the plasma membrane upon expression of activated Gα13, cellular localization of these RhoGEFs has been proposed as a mechanism for controlling their activity. We use a small molecule-regulated heterodimerization system to rapidly control the localization of RH-RhoGEFs. Acute localization of the proteins to the plasma membrane activates RhoA within minutes and to levels that are comparable with activation of RhoA by hormonal stimulation of G protein-coupled receptors. The catalytic activity of membrane-localized RhoGEFs is not dependent on activated Gα13. We further show that the conserved RH domains can rewire two different RacGEFs to activate Rac1 in response to a traditional activator of RhoA. Thus, RH domains act as independent detectors for activated Gα13 and are sufficient to modulate the activity of RhoGEFs by hormones via mediating their localization to substrate, membrane-associated RhoA.
Collapse
Affiliation(s)
- Angela M Carter
- From the Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Stephen Gutowski
- From the Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Paul C Sternweis
- From the Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| |
Collapse
|
18
|
Montgomery ER, Temple BRS, Peters KA, Tolbert CE, Booker BK, Martin JW, Hamilton TP, Tagliatela AC, Smolski WC, Rogers SL, Jones AM, Meigs TE. Gα12 structural determinants of Hsp90 interaction are necessary for serum response element-mediated transcriptional activation. Mol Pharmacol 2014; 85:586-97. [PMID: 24435554 PMCID: PMC3965892 DOI: 10.1124/mol.113.088443] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 01/16/2014] [Indexed: 12/31/2022] Open
Abstract
The G12/13 class of heterotrimeric G proteins, comprising the α-subunits Gα12 and Gα13, regulates multiple aspects of cellular behavior, including proliferation and cytoskeletal rearrangements. Although guanine nucleotide exchange factors for the monomeric G protein Rho (RhoGEFs) are well characterized as effectors of this G protein class, a variety of other downstream targets has been reported. To identify Gα12 determinants that mediate specific protein interactions, we used a structural and evolutionary comparison between the G12/13, Gs, Gi, and Gq classes to identify "class-distinctive" residues in Gα12 and Gα13. Mutation of these residues in Gα12 to their deduced ancestral forms revealed a subset necessary for activation of serum response element (SRE)-mediated transcription, a G12/13-stimulated pathway implicated in cell proliferative signaling. Unexpectedly, this subset of Gα12 mutants showed impaired binding to heat-shock protein 90 (Hsp90) while retaining binding to RhoGEFs. Corresponding mutants of Gα13 exhibited robust SRE activation, suggesting a Gα12-specific mechanism, and inhibition of Hsp90 by geldanamycin or small interfering RNA-mediated lowering of Hsp90 levels resulted in greater downregulation of Gα12 than Gα13 signaling in SRE activation experiments. Furthermore, the Drosophila G12/13 homolog Concertina was unable to signal to SRE in mammalian cells, and Gα12:Concertina chimeras revealed Gα12-specific determinants of SRE activation within the switch regions and a C-terminal region. These findings identify Gα12 determinants of SRE activation, implicate Gα12:Hsp90 interaction in this signaling mechanism, and illuminate structural features that arose during evolution of Gα12 and Gα13 to allow bifurcated mechanisms of signaling to a common cell proliferative pathway.
Collapse
Affiliation(s)
- Ellyn R Montgomery
- Department of Biology, University of North Carolina at Asheville, Asheville, North Carolina (E.R.M., B.K.B., J.W.M., T.P.H., A.C.T., W.C.S., T.E.M.); Departments of Biology (K.A.P., S.L.R., A.M.J.), Biochemistry and Biophysics (B.R.S.T.), Cell Biology and Physiology (C.E.T.), and Pharmacology (A.M.J.), R. L. Juliano Structural Bioinformatics Core Facility (B.R.S.T.), and Carolina Center for Genome Sciences (S.L.R.), University of North Carolina, and the Lineberger Comprehensive Cancer Center, (S.L.R., T.E.M.), Chapel Hill, North Carolina
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Palmitoylation of amyloid precursor protein regulates amyloidogenic processing in lipid rafts. J Neurosci 2013; 33:11169-83. [PMID: 23825420 DOI: 10.1523/jneurosci.4704-12.2013] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Brains of patients affected by Alzheimer's disease (AD) contain large deposits of aggregated amyloid β-protein (Aβ). Only a small fraction of the amyloid precursor protein (APP) gives rise to Aβ. Here, we report that ∼10% of APP undergoes a post-translational lipid modification called palmitoylation. We identified the palmitoylation sites in APP at Cys¹⁸⁶ and Cys¹⁸⁷. Surprisingly, point mutations introduced into these cysteines caused nearly complete ER retention of APP. Thus, either APP palmitoylation or disulfide bridges involving these Cys residues appear to be required for ER exit of APP. In later compartments, palmitoylated APP (palAPP) was specifically enriched in lipid rafts. In vitro BACE1 cleavage assays using cell or mouse brain lipid rafts showed that APP palmitoylation enhanced BACE1-mediated processing of APP. Interestingly, we detected an age-dependent increase in endogenous mouse brain palAPP levels. Overexpression of selected DHHC palmitoyl acyltransferases increased palmitoylation of APP and doubled Aβ production, while two palmitoylation inhibitors reduced palAPP levels and APP processing. We have found previously that acyl-coenzyme A:cholesterol acyltransferase (ACAT) inhibition led to impaired APP processing. Here we demonstrate that pharmacological inhibition or genetic inactivation of ACAT decrease lipid raft palAPP levels by up to 76%, likely resulting in impaired APP processing. Together, our results indicate that APP palmitoylation enhances amyloidogenic processing by targeting APP to lipid rafts and enhancing its BACE1-mediated cleavage. Thus, inhibition of palAPP formation by ACAT or specific palmitoylation inhibitors would appear to be a valid strategy for prevention and/or treatment of AD.
Collapse
|
20
|
The zinc-binding region of IL-2 inducible T cell kinase (Itk) is required for interaction with Gα13 and activation of serum response factor. Int J Biochem Cell Biol 2013; 45:1074-82. [PMID: 23454662 DOI: 10.1016/j.biocel.2013.02.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 02/04/2013] [Accepted: 02/18/2013] [Indexed: 11/20/2022]
Abstract
Tec family kinases play critical roles in the activation of immune cells. In particular, Itk is important for the activation of T cells via the T cell Receptor (TcR), however, molecules that cooperate with Itk to activate downstream targets remain little explored. Here we show that Itk interacts with the heterotrimeric G-protein α subunit Gα13 during TcR triggering. This interaction requires membrane localization of both partners, and is partially dependent on GDP- and GTP-bound states of Gα13. Furthermore, we find that Itk interacts with Gα13 via the zinc binding regions within its Tec homology domain. The interaction between Itk and Gα13 also results in tyrosine phosphorylation of Gα13, however this is not required for the interaction. Itk enhances Gα13 mediated activation of serum response factor (SRF) transcriptional activity dependent on its ability to interact with Gα13, but its kinase activity is not required to enhance SRF activity. These data reveal a new pathway regulated by Itk in cells, and suggest cross talk between Itk and G-protein signaling downstream of the TcR.
Collapse
|
21
|
Wright DB, Tripathi S, Sikarwar A, Santosh KT, Perez-Zoghbi J, Ojo OO, Irechukwu N, Ward JPT, Schaafsma D. Regulation of GPCR-mediated smooth muscle contraction: implications for asthma and pulmonary hypertension. Pulm Pharmacol Ther 2012; 26:121-31. [PMID: 22750270 DOI: 10.1016/j.pupt.2012.06.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2012] [Revised: 06/15/2012] [Accepted: 06/18/2012] [Indexed: 11/28/2022]
Abstract
Contractile G-protein-coupled receptors (GPCRs) have emerged as key regulators of smooth muscle contraction, both under healthy and diseased conditions. This brief review will discuss some key topics and novel insights regarding GPCR-mediated airway and vascular smooth muscle contraction as discussed at the 7th International Young Investigators' Symposium on Smooth Muscle (2011, Winnipeg, Manitoba, Canada) and will in particular focus on processes driving Ca(2+)-mobilization and -sensitization.
Collapse
Affiliation(s)
- D B Wright
- Department of Asthma, Allergy, and Lung Biology, King's College, London, United Kingdom
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Abstract
The classical view of heterotrimeric G protein signaling places G -proteins at the cytoplasmic surface of the cell's plasma membrane where they are activated by an appropriate G protein-coupled receptor. Once activated, the GTP-bound Gα and the free Gβγ are able to regulate plasma membrane-localized effectors, such as adenylyl cyclase, phospholipase C-β, RhoGEFs and ion channels. Hydrolysis of GTP by the Gα subunit returns the G protein to the inactive Gαβγ heterotrimer. Although all of these events in the G protein cycle can be restricted to the cytoplasmic surface of the plasma membrane, G protein localization is dynamic. Thus, it has become increasingly clear that G proteins are able to move to diverse subcellular locations where they perform non-canonical signaling functions. This chapter will highlight our current understanding of trafficking pathways that target newly synthesized G proteins to the plasma membrane, activation-induced and reversible translocation of G proteins from the plasma membrane to intracellular locations, and constitutive trafficking of G proteins.
Collapse
|
23
|
Wnt/β-catenin signaling is differentially regulated by Gα proteins and contributes to fibrous dysplasia. Proc Natl Acad Sci U S A 2011; 108:20101-6. [PMID: 22106277 DOI: 10.1073/pnas.1114656108] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Skeletal dysplasias are common disabling disorders characterized by aberrant growth of bone and cartilage leading to abnormal skeletal structures and functions, often attributable to defects in skeletal progenitor cells. The underlying molecular and cellular mechanisms of most skeletal dysplasias remain elusive. Although the Wnt/β-catenin signaling pathway is required for skeletal progenitor cells to differentiate along the osteoblastic lineage, inappropriately elevated levels of signaling can also inhibit bone formation by suppressing osteoblast maturation. Here, we investigate interactions of the four major Gα protein families (Gα(s), Gα(i/o), Gα(q/11), and Gα(12/13)) with the Wnt/β-catenin signaling pathway and identify a causative role of Wnt/β-catenin signaling in fibrous dysplasia (FD) of bone, a disease that exhibits abnormal differentiation of skeletal progenitor cells. The activating Gα(s) mutations that cause FD potentiated Wnt/β-catenin signaling, and removal of Gα(s) led to reduced Wnt/β-catenin signaling and decreased bone formation. We further show that activation of Wnt/β-catenin signaling in osteoblast progenitors results in an FD-like phenotype and reduction of β-catenin levels rescued differentiation defects of FD patient-derived stromal cells. Gα proteins may act at the level of β-catenin destruction complex assembly by binding Axin. Our results indicate that activated Gα proteins differentially regulate Wnt/β-catenin signaling but, importantly, are not required core components of Wnt/β-catenin signaling. Our data suggest that activated Gα proteins are playing physiologically significant roles during both skeletal development and disease by modulating Wnt/β-catenin signaling strength.
Collapse
|
24
|
Guan X, Fierke CA. Understanding Protein Palmitoylation: Biological Significance and Enzymology. Sci China Chem 2011; 54:1888-1897. [PMID: 25419213 DOI: 10.1007/s11426-011-4428-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Protein palmitoylation is a widespread lipid modification in which one or more cysteine thiols on a substrate protein are modified to form a thioester with a palmitoyl group. This lipid modification is readily reversible; a feature of protein palmitoylation that allows for rapid regulation of the function of many cellular proteins. Mutations in palmitoyltransferases (PATs), the enzymes that catalyze the formation of this modification, are associated with a number of neurological diseases and cancer progression. This review summarizes the crucial role of palmitoylation in biological systems, the discovery of the DHHC protein family that catalyzes protein palmitoylation, and the development of methods for investigating the catalytic mechanism of PATs.
Collapse
Affiliation(s)
- Xiaomu Guan
- Departments of Chemistry and Biological Chemistry, University of Michigan, 930 N University, Ann Arbor, MI 48109-1055, USA
| | - Carol A Fierke
- Departments of Chemistry and Biological Chemistry, University of Michigan, 930 N University, Ann Arbor, MI 48109-1055, USA
| |
Collapse
|
25
|
Kozasa T, Hajicek N, Chow CR, Suzuki N. Signalling mechanisms of RhoGTPase regulation by the heterotrimeric G proteins G12 and G13. J Biochem 2011; 150:357-69. [PMID: 21873336 DOI: 10.1093/jb/mvr105] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
G protein-mediated signal transduction can transduce signals from a large variety of extracellular stimuli into cells and is the most widely used mechanism for cell communication at the membrane. The RhoGTPase family has been well established as key regulators of cell growth, differentiation and cell shape changes. Among G protein-mediated signal transduction, G12/13-mediated signalling is one mechanism to regulate RhoGTPase activity in response to extracellular stimuli. The alpha subunits of G12 or G13 have been shown to interact with members of the RH domain containing guanine nucleotide exchange factors for Rho (RH-RhoGEF) family of proteins to directly connect G protein-mediated signalling and RhoGTPase signalling. The G12/13-RH-RhoGEF signalling mechanism is well conserved over species and is involved in critical steps for cell physiology and disease conditions, including embryonic development, oncogenesis and cancer metastasis. In this review, we will summarize current progress on this important signalling mechanism.
Collapse
Affiliation(s)
- Tohru Kozasa
- Laboratory of Systems Biology and Medicine, Research Center for Advanced Science and Technology, University of Tokyo, Tokyo 153-8904, Japan.
| | | | | | | |
Collapse
|
26
|
Aittaleb M, Nishimura A, Linder ME, Tesmer JJG. Plasma membrane association of p63 Rho guanine nucleotide exchange factor (p63RhoGEF) is mediated by palmitoylation and is required for basal activity in cells. J Biol Chem 2011; 286:34448-56. [PMID: 21832057 DOI: 10.1074/jbc.m111.273342] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of G protein-coupled receptors at the cell surface leads to the activation or inhibition of intracellular effector enzymes, which include various Rho guanine nucleotide exchange factors (RhoGEFs). RhoGEFs activate small molecular weight GTPases at the plasma membrane (PM). Many of the known G protein-coupled receptor-regulated RhoGEFs are found in the cytoplasm of unstimulated cells, and PM recruitment is a critical aspect of their regulation. In contrast, p63RhoGEF, a Gα(q)-regulated RhoGEF, appears to be constitutively localized to the PM. The objective of this study was to determine the molecular basis for the localization of p63RhoGEF and the impact of its subcellular localization on its regulation by Gα(q). Herein, we show that the pleckstrin homology domain of p63RhoGEF is not involved in its PM targeting. Instead, a conserved string of cysteines (Cys-23/25/26) at the N terminus of the enzyme is palmitoylated and required for membrane localization and full basal activity in cells. Conversion of these residues to serine relocates p63RhoGEF from the PM to the cytoplasm, diminishes its basal activity, and eliminates palmitoylation. The activity of palmitoylation-deficient p63RhoGEF can be rescued by targeting to the PM by fusion with tandem phospholipase C-δ1 pleckstrin homology domains or by co-expression with wild-type Gα(q) but not with palmitoylation-deficient Gα(q). Our data suggest that p63RhoGEF is regulated chiefly through allosteric control by Gα(q), as opposed to other known Gα-regulated RhoGEFs, which are instead sequestered in the cytoplasm, perhaps because of their high basal activity.
Collapse
Affiliation(s)
- Mohamed Aittaleb
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109-2216, USA
| | | | | | | |
Collapse
|
27
|
Morin RD, Mendez-Lago M, Mungall AJ, Goya R, Mungall KL, Corbett R, Johnson NA, Severson TM, Chiu R, Field M, Jackman S, Krzywinski M, Scott DW, Trinh DL, Tamura-Wells J, Li S, Firme M, Rogic S, Griffith M, Chan S, Yakovenko O, Meyer IM, Zhao EY, Smailus D, Moksa M, Chittaranjan S, Rimsza L, Brooks-Wilson A, Spinelli JJ, Ben-Neriah S, Meissner B, Woolcock B, Boyle M, McDonald H, Tam A, Zhao Y, Delaney A, Zeng T, Tse K, Butterfield Y, Birol I, Holt R, Schein J, Horsman DE, Moore R, Jones SJ, Connors JM, Hirst M, Gascoyne RD, Marra MA. Frequent mutation of histone-modifying genes in non-Hodgkin lymphoma. Nature 2011; 476:298-303. [PMID: 21796119 PMCID: PMC3210554 DOI: 10.1038/nature10351] [Citation(s) in RCA: 1243] [Impact Index Per Article: 95.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Accepted: 07/07/2011] [Indexed: 12/11/2022]
Abstract
Follicular lymphoma (FL) and diffuse large B-cell lymphoma (DLBCL) are the two most common non-Hodgkin lymphomas (NHLs). Here we sequenced tumour and matched normal DNA from 13 DLBCL cases and one FL case to identify genes with mutations in B-cell NHL. We analysed RNA-seq data from these and another 113 NHLs to identify genes with candidate mutations, and then re-sequenced tumour and matched normal DNA from these cases to confirm 109 genes with multiple somatic mutations. Genes with roles in histone modification were frequent targets of somatic mutation. For example, 32% of DLBCL and 89% of FL cases had somatic mutations in MLL2, which encodes a histone methyltransferase, and 11.4% and 13.4% of DLBCL and FL cases, respectively, had mutations in MEF2B, a calcium-regulated gene that cooperates with CREBBP and EP300 in acetylating histones. Our analysis suggests a previously unappreciated disruption of chromatin biology in lymphomagenesis.
Collapse
Affiliation(s)
- Ryan D. Morin
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | | | | | - Rodrigo Goya
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | | | - Richard Corbett
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | | | | | - Readman Chiu
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Matthew Field
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Shaun Jackman
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | | | | | - Diane L. Trinh
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | | | - Sa Li
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Marlo Firme
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Sanja Rogic
- Centre for Lymphoid Cancer, BC Cancer Agency
| | | | - Susanna Chan
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | | | | | - Eric Y. Zhao
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Duane Smailus
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Michelle Moksa
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | | | - Lisa Rimsza
- Department of Pathology, University of Arizona
| | - Angela Brooks-Wilson
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University
| | - John J. Spinelli
- Cancer Control Research, BC Cancer Agency
- School of Population and Public Health, University of British Columbia
| | | | | | | | | | - Helen McDonald
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Angela Tam
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Yongjun Zhao
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Allen Delaney
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Thomas Zeng
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Kane Tse
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | | | - Inanc Birol
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Rob Holt
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | | | | | - Richard Moore
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | | | | | - Martin Hirst
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
| | - Randy D. Gascoyne
- Centre for Lymphoid Cancer, BC Cancer Agency
- Department of Pathology, University of British Columbia
| | - Marco A. Marra
- Canada’s Michael Smith Genome Sciences Centre, BC Cancer Agency
- Department of Medical Genetics, University of British Columbia
| |
Collapse
|
28
|
Hajicek N, Kukimoto-Niino M, Mishima-Tsumagari C, Chow CR, Shirouzu M, Terada T, Patel M, Yokoyama S, Kozasa T. Identification of critical residues in G(alpha)13 for stimulation of p115RhoGEF activity and the structure of the G(alpha)13-p115RhoGEF regulator of G protein signaling homology (RH) domain complex. J Biol Chem 2011; 286:20625-36. [PMID: 21507947 PMCID: PMC3121507 DOI: 10.1074/jbc.m110.201392] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 04/08/2011] [Indexed: 01/28/2023] Open
Abstract
RH-RhoGEFs are a family of guanine nucleotide exchange factors that contain a regulator of G protein signaling homology (RH) domain. The heterotrimeric G protein Gα(13) stimulates the guanine nucleotide exchange factor (GEF) activity of RH-RhoGEFs, leading to activation of RhoA. The mechanism by which Gα(13) stimulates the GEF activity of RH-RhoGEFs, such as p115RhoGEF, has not yet been fully elucidated. Here, specific residues in Gα(13) that mediate activation of p115RhoGEF are identified. Mutation of these residues significantly impairs binding of Gα(13) to p115RhoGEF as well as stimulation of GEF activity. These data suggest that the exchange activity of p115RhoGEF is stimulated allosterically by Gα(13) and not through its interaction with a secondary binding site. A crystal structure of Gα(13) bound to the RH domain of p115RhoGEF is also presented, which differs from a previously crystallized complex with a Gα(13)-Gα(i1) chimera. Taken together, these data provide new insight into the mechanism by which p115RhoGEF is activated by Gα(13).
Collapse
Affiliation(s)
- Nicole Hajicek
- Department of Pharmacology, College of Medicine, University of Illinois, Chicago, Illinois 60612, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
29
|
microRNAs in neurons: manifold regulatory roles at the synapse. Curr Opin Genet Dev 2011; 21:491-7. [PMID: 21561760 DOI: 10.1016/j.gde.2011.04.008] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 04/08/2011] [Accepted: 04/12/2011] [Indexed: 01/22/2023]
Abstract
The regulation of synapse formation and plasticity in the developing and adult brain underlies a complex interplay of intrinsic genetic programs and extrinsic factors. Recent research identified microRNAs (miRNAs), a class of small non-coding RNAs, as a new functional layer in this regulatory network. Within only a few years, a network of synaptic miRNAs and their target genes has been extensively characterized, highlighting the importance of this mechanism for synapse development and physiology. Very recent data further provide insight into activity-dependent regulation of miRNAs, thereby connecting miRNAs with adaptive processes of neural circuits. First direct links between miRNA dysfunction and synaptic pathologies are emerging, raising the interest in these molecules as potential biomarkers and therapeutic targets in neurological disorders.
Collapse
|
30
|
Ocaña-Morgner C, Reichardt P, Chopin M, Braungart S, Wahren C, Gunzer M, Jessberger R. Sphingosine 1-phosphate-induced motility and endocytosis of dendritic cells is regulated by SWAP-70 through RhoA. THE JOURNAL OF IMMUNOLOGY 2011; 186:5345-55. [PMID: 21421853 DOI: 10.4049/jimmunol.1003461] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The phospholipid mediator sphingosine 1-phosphate (S1P) enhances motility and endocytosis of mature dendritic cells (DCs). We show that in vitro migration of Swap-70(-/-) bone marrow-derived DCs (BMDCs) in response to S1P and S1P-induced upregulation of endocytosis are significantly reduced. S1P-stimulated movement of Swap-70(-/-) BMDCs, specifically retraction of their trailing edge, in a collagen three-dimensional environment is impaired. These in vitro observations correlate with delayed entry into lymphatic vessels and migration to lymph nodes of skin DCs in Swap-70(-/-) mice. Expression of S1P receptors (S1P(1-3)) by wild-type and Swap-70(-/-) BMDCs is similar, but Swap-70(-/-) BMDCs fail to activate RhoA and to localize Rac1 and RhoA into areas of actin polymerization after S1P stimulus. The Rho-activating G protein Gα(i) interacts with SWAP-70, which also supports the localization of Gα(13) to membrane rafts in BMDCs. LPS-matured Swap-70(-/-) BMDCs contain significantly more active RhoA than wild-type DCs. Preinhibition of Rho activation restored migration to S1P, S1P-induced upregulation of endocytosis in mature Swap-70(-/-) BMDCs, and localization of Gα(13) to membrane rafts. These data demonstrate SWAP-70 as a novel regulator of S1P signaling necessary for DC motility and endocytosis.
Collapse
Affiliation(s)
- Carlos Ocaña-Morgner
- Faculty of Medicine Carl Gustav Carus, Institute of Physiological Chemistry, Dresden University of Technology, D-01307 Dresden, Germany.
| | | | | | | | | | | | | |
Collapse
|
31
|
Small molecule inhibition of protein depalmitoylation as a new approach towards downregulation of oncogenic Ras signalling. Bioorg Med Chem 2011; 19:1376-80. [DOI: 10.1016/j.bmc.2010.11.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 11/08/2010] [Accepted: 11/08/2010] [Indexed: 01/18/2023]
|
32
|
Chen Z, Medina F, Liu MY, Thomas C, Sprang SR, Sternweis PC. Activated RhoA binds to the pleckstrin homology (PH) domain of PDZ-RhoGEF, a potential site for autoregulation. J Biol Chem 2010; 285:21070-81. [PMID: 20430886 PMCID: PMC2898337 DOI: 10.1074/jbc.m110.122549] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 04/15/2010] [Indexed: 01/24/2023] Open
Abstract
Guanine nucleotide exchange factors (GEFs) catalyze exchange of GDP for GTP by stabilizing the nucleotide-free state of the small GTPases through their Dbl homology/pleckstrin homology (DH.PH) domains. Unconventionally, PDZ-RhoGEF (PRG), a member of the RGS-RhoGEFs, binds tightly to both nucleotide-free and activated RhoA (RhoA.GTP). We have characterized the interaction between PRG and activated RhoA and determined the structure of the PRG-DH.PH-RhoA.GTPgammaS (guanosine 5'-O-[gamma-thio]triphosphate) complex. The interface bears striking similarity to a GTPase-effector interface and involves the switch regions in RhoA and a hydrophobic patch in PRG-PH that is conserved among all Lbc RhoGEFs. The two surfaces that bind activated and nucleotide-free RhoA on PRG-DH.PH do not overlap, and a ternary complex of PRG-DH.PH bound to both forms of RhoA can be isolated by size-exclusion chromatography. This novel interaction between activated RhoA and PH could play a key role in regulation of RhoGEF activity in vivo.
Collapse
Affiliation(s)
- Zhe Chen
- From the Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390 and
| | - Frank Medina
- From the Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390 and
| | - Mu-ya Liu
- From the Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390 and
| | - Celestine Thomas
- the Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, Montana 59812
| | - Stephen R. Sprang
- the Center for Biomolecular Structure and Dynamics, Division of Biological Sciences, University of Montana, Missoula, Montana 59812
| | - Paul C. Sternweis
- From the Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390 and
| |
Collapse
|
33
|
Shankaranarayanan A, Boguth CA, Lutz S, Vettel C, Uhlemann F, Aittaleb M, Wieland T, Tesmer JJG. Galpha q allosterically activates and relieves autoinhibition of p63RhoGEF. Cell Signal 2010; 22:1114-23. [PMID: 20214977 DOI: 10.1016/j.cellsig.2010.03.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 03/01/2010] [Indexed: 01/01/2023]
Abstract
Galpha(q) directly activates p63RhoGEF and closely related catalytic domains found in Trio and Kalirin, thereby linking G(q)-coupled receptors to the activation of RhoA. Although the crystal structure of G alpha(q) in complex with the catalytic domains of p63RhoGEF is available, the molecular mechanism of activation has not yet been defined. In this study, we show that membrane translocation does not appear to play a role in G alpha(q)-mediated activation of p63RhoGEF, as it does in some other RhoGEFs. G alpha(q) instead must act allosterically. We next identify specific structural elements in the PH domain that inhibit basal nucleotide exchange activity, and provide evidence that G alpha(q) overcomes this inhibition by altering the conformation of the alpha 6-alpha N linker that joins the DH and PH domains, a region that forms direct contacts with RhoA. We also identify residues in G alpha(q) that are important for the activation of p63RhoGEF and that contribute to G alpha subfamily selectivity, including a critical residue in the G alpha(q) C-terminal helix, and demonstrate the importance of these residues for RhoA activation in living cells.
Collapse
|
34
|
Sabbatini ME, Bi Y, Ji B, Ernst SA, Williams JA. CCK activates RhoA and Rac1 differentially through Galpha13 and Galphaq in mouse pancreatic acini. Am J Physiol Cell Physiol 2009; 298:C592-601. [PMID: 19940064 DOI: 10.1152/ajpcell.00448.2009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cholecystokinin (CCK) has been shown to activate RhoA and Rac1, as well as reorganize the actin cytoskeleton and, thereby, modify acinar morphology and amylase secretion in mouse pancreatic acini. The aim of the present study was to determine which heterotrimeric G proteins activate RhoA and Rac1 upon CCK stimulation. Galpha(13), but not Galpha(12), was identified in mouse pancreatic acini by RT-PCR and Western blotting. Using specific assays for RhoA and Rac1 activation, we showed that only active Galpha(13) activated RhoA. By contrast, active Galpha(13) and Galpha(q), but not Galpha(s), slightly increased GTP-bound Rac1 levels. A greater increase in Rac1 activation was observed when active Galpha(13) and active Galpha(q) were coexpressed. Galpha(i) was not required for CCK-induced RhoA or Rac1 activation. The regulator of G protein signaling (RGS) domain of p115-Rho guanine nucleotide exchange factor (p115-RGS), a specific inhibitor of Galpha(12/13)-mediated signaling, abolished CCK-stimulated RhoA activation. By contrast, both RGS-2, an inhibitor of Galpha(q), and p115-RGS abolished CCK-induced Rac1 activation, which was PLC pathway-independent. Active Galpha(q) and Galpha(13), but not Galpha(s), induced morphological changes and actin redistribution similar to 1 nM CCK. CCK-induced actin cytoskeletal reorganization was inhibited by RGS-2, but not by p115-RGS, whereas CCK-induced amylase secretion was blocked by both inhibitors. Together, these findings indicate that, in mouse pancreatic acini, Galpha(13) links CCK stimulation to the activation of RhoA, whereas both Galpha(13) and Galpha(q) link CCK stimulation to the activation of Rac1. CCK-induced actin cytoskeletal reorganization is mainly mediated by Galpha(q). By contrast, Galpha(13) and Galpha(q) signaling are required for CCK-induced amylase secretion.
Collapse
Affiliation(s)
- Maria E Sabbatini
- Department of Molecular and Integrative Physiology, The University of Michigan, Ann Arbor, Michigan, USA.
| | | | | | | | | |
Collapse
|
35
|
Tesmer JJG. Structure and function of regulator of G protein signaling homology domains. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 86:75-113. [PMID: 20374714 DOI: 10.1016/s1877-1173(09)86004-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
All regulator of G protein signaling (RGS) proteins contain a conserved domain of approximately 130 amino acids that binds to activated heterotrimeric G protein α subunits (Gα) and accelerates their rate of GTP hydrolysis. Homologous domains are found in at least six other protein families, including a family of Rho guanine nucleotide exchange factors (RhoGEFs) and the G protein-coupled receptor kinases (GRKs). Although some of the RhoGEF and GRK RGS-like domains can also bind to activated Gα subunits, they do so in distinct ways and with much lower levels of GTPase activation. In other protein families, the domains have as of yet no obvious relationship to heterotrimeric G protein signaling. These RGS homology (RH) domains are now recognized as mediators of extraordinarily diverse protein-protein interactions. Through these interactions, they play roles that range from enzyme to molecular scaffold to signal transducing module. In this review, the atomic structures of RH domains from RGS proteins, Axins, RhoGEFs, and GRKs are compared in light of what is currently known about their functional roles.
Collapse
Affiliation(s)
- John J G Tesmer
- Department of Pharmacology, Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109‐2216, USA
| |
Collapse
|
36
|
A conserved hydrophobic surface of the LARG pleckstrin homology domain is critical for RhoA activation in cells. Cell Signal 2009; 21:1569-78. [PMID: 19560536 DOI: 10.1016/j.cellsig.2009.06.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Accepted: 06/16/2009] [Indexed: 01/23/2023]
Abstract
Leukemia associated Rho guanine nucleotide exchange factor (LARG) activates RhoA in response to signals received by specific classes of cell surface receptors. The catalytic core of LARG is a Dbl homology (DH) domain whose activity is modulated by an adjacent pleckstrin homology (PH) domain. In this study, we used a transcriptional assay and confocal microscopy to examine the roles of several novel structural features of the LARG DH/PH domains, including a conserved and exposed hydrophobic patch on the PH domain that mediates protein-protein interactions in crystal structures of LARG and its close homolog PDZ-RhoGEF. Mutation of the hydrophobic patch has no effect on nucleotide exchange activity in vitro, but abolished the ability of LARG to activate RhoA and to induce stress fiber formation in cultured cells. The activity of these mutants could be rescued by fusion with exogenous membrane-targeting domains. However, because membrane recruitment by activated G alpha(13) subunits was not sufficient to rescue activity of a hydrophobic patch mutant, the LARG PH domain cannot solely contribute to membrane targeting. Instead, it seems likely that the domain is involved in regulatory interactions with other proteins near the membrane surface. We also show that the hydrophobic patch of the PH domain is likely important for the activity of all Lbc subfamily RhoGEFs.
Collapse
|
37
|
MicroRNA-mediated regulation of synaptic palmitoylation: shrinking fat spines. Nat Cell Biol 2009; 11:681-2. [DOI: 10.1038/ncb0609-681] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
|
38
|
Siegel G, Obernosterer G, Fiore R, Oehmen M, Bicker S, Christensen M, Khudayberdiev S, Leuschner PF, Busch CJL, Kane C, Hübel K, Dekker F, Hedberg C, Rengarajan B, Drepper C, Waldmann H, Kauppinen S, Greenberg ME, Draguhn A, Rehmsmeier M, Martinez J, Schratt GM. A functional screen implicates microRNA-138-dependent regulation of the depalmitoylation enzyme APT1 in dendritic spine morphogenesis. Nat Cell Biol 2009; 11:705-16. [PMID: 19465924 DOI: 10.1038/ncb1876] [Citation(s) in RCA: 388] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Accepted: 02/10/2009] [Indexed: 02/06/2023]
Abstract
The microRNA pathway has been implicated in the regulation of synaptic protein synthesis and ultimately in dendritic spine morphogenesis, a phenomenon associated with long-lasting forms of memory. However, the particular microRNAs (miRNAs) involved are largely unknown. Here we identify specific miRNAs that function at synapses to control dendritic spine structure by performing a functional screen. One of the identified miRNAs, miR-138, is highly enriched in the brain, localized within dendrites and negatively regulates the size of dendritic spines in rat hippocampal neurons. miR-138 controls the expression of acyl protein thioesterase 1 (APT1), an enzyme regulating the palmitoylation status of proteins that are known to function at the synapse, including the alpha(13) subunits of G proteins (Galpha(13)). RNA-interference-mediated knockdown of APT1 and the expression of membrane-localized Galpha(13) both suppress spine enlargement caused by inhibition of miR-138, suggesting that APT1-regulated depalmitoylation of Galpha(13) might be an important downstream event of miR-138 function. Our results uncover a previously unknown miRNA-dependent mechanism in neurons and demonstrate a previously unrecognized complexity of miRNA-dependent control of dendritic spine morphogenesis.
Collapse
Affiliation(s)
- Gabriele Siegel
- Interdisziplinäres Zentrum für Neurowissenschaften, SFB488 Junior Group, Universität Heidelberg, and Institut für Neuroanatomie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 345, 69120 Heidelberg, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
39
|
Zheng M, Cierpicki T, Momotani K, Artamonov MV, Derewenda U, Bushweller JH, Somlyo AV, Derewenda ZS. On the mechanism of autoinhibition of the RhoA-specific nucleotide exchange factor PDZRhoGEF. BMC STRUCTURAL BIOLOGY 2009; 9:36. [PMID: 19460155 PMCID: PMC2695464 DOI: 10.1186/1472-6807-9-36] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Accepted: 05/21/2009] [Indexed: 11/10/2022]
Abstract
Background The Dbl-family of guanine nucleotide exchange factors (GEFs) activate the cytosolic GTPases of the Rho family by enhancing the rate of exchange of GTP for GDP on the cognate GTPase. This catalytic activity resides in the DH (Dbl-homology) domain, but typically GEFs are multidomain proteins containing other modules. It is believed that GEFs are autoinhibited in the cytosol due to supramodular architecture, and become activated in diverse signaling pathways through conformational change and exposure of the DH domain, as the protein is translocated to the membrane. A small family of RhoA-specific GEFs, containing the RGSL (regulators of G-protein signaling-like) domain, act as effectors of select GPCRs via Gα12/13, although the molecular mechanism by which this pathway operates is not known. These GEFs include p115, LARG and PDZRhoGEF (PRG). Results Here we show that the autoinhibition of PRG is caused largely by an interaction of a short negatively charged sequence motif, immediately upstream of the DH-domain and including residues Asp706, Glu708, Glu710 and Asp712, with a patch on the catalytic surface of the DH-domain including Arg867 and Arg868. In the absence of both PDZ and RGSL domains, the DH-PH tandem with additional 21 residues upstream, is 50% autoinhibited. However, within the full-length protein, the PDZ and/or RGSL domains significantly restore autoinhibition. Conclusion Our results suggest a mechanism for autoinhibition of RGSL family of GEFs, in which the RGSL domain and a unique sequence motif upstream of the DH domain, act cooperatively to reduce the ability of the DH domain to bind the nucleotide free RhoA. The activation mechanism is likely to involve two independent steps, i.e. displacement of the RGSL domain and conformational change involving the autoinhibitory sequence motif containing several negatively charged residues.
Collapse
Affiliation(s)
- Meiying Zheng
- Department of Molecular Physiology and Biological Physics, University of Virginia, PO Box 800736, Charlottesville, Virginia, 22908-0736, USA.
| | | | | | | | | | | | | | | |
Collapse
|
40
|
Differences in Galpha12- and Galpha13-mediated plasma membrane recruitment of p115-RhoGEF. Cell Signal 2009; 21:996-1006. [PMID: 19249348 DOI: 10.1016/j.cellsig.2009.02.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 02/16/2009] [Accepted: 02/17/2009] [Indexed: 11/22/2022]
Abstract
Regulator of G protein signaling domain-containing Rho guanine-nucleotide exchange factors (RGS-RhoGEFs) directly links activated forms of the G12 family of heterotrimeric G protein alpha subunits to the small GTPase Rho. Stimulation of G(12/13)-coupled GPCRs or expression of constitutively activated forms of alpha(12) and alpha(13) has been shown to induce the translocation of the RGS-RhoGEF, p115-RhoGEF, from the cytoplasm to the plasma membrane (PM). However, little is known regarding the functional importance and mechanisms of this regulated PM recruitment, and thus PM recruitment of p115-RhoGEF is the focus of this report. A constitutively PM-localized mutant of p115-RhoGEF shows a much greater activity compared to wild type p115-RhoGEF in promoting Rho-dependent neurite retraction of NGF-differentiated PC12 cells, providing the first evidence that PM localization can activate p115-RhoGEF signaling. Next, we uncovered the unexpected finding that Rho is required for alpha(13)-induced PM translocation of p115-RhoGEF. However, inhibition of Rho did not prevent alpha(12)-induced PM translocation of p115-RhoGEF. Additional differences between alpha(13) and alpha(12) in promoting PM recruitment of p115-RhoGEF were revealed by analyzing RGS domain mutants of p115-RhoGEF. Activated alpha(12) effectively recruits the isolated RGS domain of p115-RhoGEF to the PM, whereas alpha(13) only weakly does. On the other hand, alpha(13) strongly recruits to the PM a p115-RhoGEF mutant containing amino acid substitutions in an acidic region at the N-terminus of the RGS domain; however, alpha(12) is unable to recruit this p115-RhoGEF mutant to the PM. These studies provide new insight into the function and mechanisms of alpha(12/13)-mediated PM recruitment of p115-RhoGEF.
Collapse
|
41
|
Suzuki N, Hajicek N, Kozasa T. Regulation and physiological functions of G12/13-mediated signaling pathways. Neurosignals 2009; 17:55-70. [PMID: 19212140 DOI: 10.1159/000186690] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Accepted: 10/10/2008] [Indexed: 12/12/2022] Open
Abstract
Accumulating data indicate that G12 subfamily (Galpha12/13)-mediated signaling pathways play pivotal roles in a variety of physiological processes, while aberrant regulation of this pathway has been identified in various human diseases. It has been demonstrated that Galpha12/13-mediated signals form networks with other signaling proteins at various levels, from cell surface receptors to transcription factors, to regulate cellular responses. Galpha12/13 have slow rates of nucleotide exchange and GTP hydrolysis, and specifically target RhoGEFs containing an amino-terminal RGS homology domain (RH-RhoGEFs), which uniquely function both as a GAP and an effector for Galpha12/13. In this review, we will focus on the mechanisms regulating the Galpha12/13 signaling system, particularly the Galpha12/13-RH-RhoGEF-Rho pathway, which can regulate a wide variety of cellular functions from migration to transformation.
Collapse
Affiliation(s)
- Nobuchika Suzuki
- Laboratory of Systems Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan.
| | | | | |
Collapse
|
42
|
Porchia F, Papucci M, Gargini C, Asta A, De Marco G, Agretti P, Tonacchera M, Mazzoni MR. Endothelin-1 up-regulates p115RhoGEF in embryonic rat cardiomyocytes during the hypertrophic response. J Recept Signal Transduct Res 2008; 28:265-83. [PMID: 18569527 DOI: 10.1080/10799890802084515] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
In cardiomyocytes, certain extracellular stimuli that activate heterotrimeric G protein-coupled receptors (GPCRs) can induce hypertrophy by regulating gene expression and increasing protein synthesis. We investigated if rat embryonic cardiomyocytes (H9c2) underwent variations in the expression levels and subcellular distribution of key components of GPCR-activated signaling pathways during endothelin-1 (ET-1)-induced hypertrophic response. A significant increase of p115RhoGEF protein level was evident in ET-1-treated cells. Real-time quantitative PCR showed RhoGEF mRNA levels were significantly increased. Inhibition of the Rho-associated kinase (ROCK) caused a significant decrease of p115RhoGEF protein in the nuclear fraction, whereas an inhibitor of PKC induced a redistribution of the protein between membrane/organelle and nuclear fractions. The ROCK inhibitor also decreased H9c2 cell hypertrophic response. These results indicate that ROCK and its downstream target molecules, which are involved in inducing the hypertrophic response, are also implicated in signaling the up-regulation of the p115RhoGEF protein.
Collapse
Affiliation(s)
- Francesca Porchia
- Dipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, University of Pisa, Pisa, Italy
| | | | | | | | | | | | | | | |
Collapse
|
43
|
Bhattacharyya R, Noch EK, Khalili K. A novel role of Rac1 GTPase in JCV T-antigen-mediated beta-catenin stabilization. Oncogene 2007; 26:7628-36. [PMID: 17637758 DOI: 10.1038/sj.onc.1210576] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Wnt signaling follows canonical and non-canonical pathways to regulate a variety of processes during cellular homeostasis and development. The large T-antigen (T-Ag) of the human neurotropic JC virus, has been shown to modulate the Wnt-signaling pathway via interaction with beta-catenin, one of the most important components of the canonical Wnt pathway. Here, we have identified an alternative non-canonical pathway that allows T-Ag to recruit Rac1 for stabilizing beta-catenin by inhibiting its ubiquitin-dependent proteasomal degradation. We demonstrate that inhibition of Rac1 by its dominant negative mutant, RacN17, abrogates T-Ag-mediated stabilization of beta-catenin yet exhibits no impact on the transcriptional activity of beta-catenin. Results from immunocytochemistry revealed that together with T-Ag, a pool of beta-catenin appears at the cell surface, particularly at the membrane ruffles where active Rac1 is positioned. Interestingly, cooperativity between T-Ag and beta-catenin leads to activation of Rac1, which in turn, stimulates its association with beta-catenin. These observations unravel the interplay between beta-catenin and Rac1 that is initiated by T-Ag and results in stabilization of beta-catenin and its presence in cell membrane ruffles.
Collapse
Affiliation(s)
- R Bhattacharyya
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, Philadelphia, PA 19122, USA
| | | | | |
Collapse
|
44
|
Grabocka E, Wedegaertner PB. Disruption of oligomerization induces nucleocytoplasmic shuttling of leukemia-associated rho Guanine-nucleotide exchange factor. Mol Pharmacol 2007; 72:993-1002. [PMID: 17609419 DOI: 10.1124/mol.107.035162] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The rgsRhoGEFs comprise a subfamily of three guanine nucleotide exchange factors, which function in linking heterotrimeric G-proteins to the monomeric RhoGTPase. Here, we reveal the novel finding that oligomerization of leukemia-associated RhoGEF (LARG) functions to prevent nucleocytoplasmic shuttling and to retain LARG in the cytoplasm. We establish that oligomerization is mediated by a predicted coiled-coil sequence (amino acids 1507-1520) in the extreme C terminus of LARG and that substitution of isoleucines 1507/1510 with alanines disrupts homo-oligomerization and leads to nucleocytoplasmic shuttling via the CRM1 nuclear transport pathway. In addition, we demonstrate that induced dimerization of an otherwise nuclear monomeric LARG mutant promotes cytoplasmic localization. Furthermore, we establish that nuclear import of monomeric LARG is mediated by the nuclear localization sequence (29)PTDKKQK(35) in the extreme N terminus. We propose that nucleocytoplasmic shuttling provides a mechanism for spatially regulating the activity of LARG toward its cytoplasmic targets and potentially new nuclear targets.
Collapse
Affiliation(s)
- Elda Grabocka
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 S. 10 Street, 839 BLSB, Philadelphia, PA 19107, USA
| | | |
Collapse
|
45
|
Sternweis PC, Carter AM, Chen Z, Danesh SM, Hsiung YF, Singer WD. Regulation of Rho guanine nucleotide exchange factors by G proteins. ADVANCES IN PROTEIN CHEMISTRY 2007; 74:189-228. [PMID: 17854659 DOI: 10.1016/s0065-3233(07)74006-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Monomeric Rho GTPases regulate cellular dynamics through remodeling of the cytoskeleton, modulation of immediate signaling pathways, and longer-term regulation of gene transcription. One family of guanine nucleotide exchange factors for Rho proteins (RhoGEFs) provides a direct pathway for regulation of RhoA by cell surface receptors coupled to heterotrimeric G proteins. Some of these RhoGEFs also contain RGS domains that can attenuate signaling by the G(12) and G(13) proteins. The regulation provided by these RhoGEFs is defined by their selective regulation by specific G proteins, phosphorylation by kinases, and potential localization with signaling partners. Evidence of their physiological importance is derived from gene knockouts in Drosophila and mice. Current understanding of the basic regulatory mechanisms of these RhoGEFs is discussed. An overview of identified interactions with other signaling proteins suggests the growing spectrum of their involvement in numerous signaling pathways.
Collapse
Affiliation(s)
- Paul C Sternweis
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | | | | | | | | | | |
Collapse
|
46
|
Tamma G, Carmosino M, Svelto M, Valenti G. Bradykinin signaling counteracts cAMP-elicited aquaporin 2 translocation in renal cells. J Am Soc Nephrol 2005; 16:2881-9. [PMID: 16093449 DOI: 10.1681/asn.2005020190] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Bradykinin (BK) is one of the most important peptides regulating vascular tone, water, and ionic balance in the body, playing a key role in controlling BP. It is interesting that patients with essential hypertension excrete less BK than normotensive individuals. For elucidating the mechanism by which BK regulates renal water transport that contributes to its antihypertensive effect, aquaporin 2 (AQP2)-transfected collecting duct CD8 cells, expressing the BK type II receptor (BK2R), were used as an experimental model. In CD8 cells, BK pretreatment impaired forskolin-induced AQP2 translocation to the apical plasma membrane. For clarifying the signal transduction cascade associated with this effect, whether BK induced an increase in cytosolic calcium, via the G protein Gq, known to be coupled to BK2R, first was investigated. Spectrofluorometry using fura-2-AM revealed that 100 nM BK elicited a significant increase in Ca(i), which was abolished by the receptor antagonist HOE-140. BK acts through BK2R coupled to both Gq and Galpha13, a known upstream effector of Rho protein. In CD8 cells, BK causes an increase in Rho activity, likely as a result of Galpha13 activation. This results in stabilization of the cortical F-actin network, thus impairing AQP2 trafficking. These effects counteract physiologic vasopressin stimulation, which instead has an opposite effect on actin network organization through Rho inactivation.
Collapse
Affiliation(s)
- Grazia Tamma
- Dipartimento di Fisiologia Generale e Ambientale, Via Amendola 165/A, Bari 70126, Italy
| | | | | | | |
Collapse
|
47
|
Yamazaki J, Katoh H, Yamaguchi Y, Negishi M. Two G12 family G proteins, G alpha12 and G alpha13, show different subcellular localization. Biochem Biophys Res Commun 2005; 332:782-6. [PMID: 15907792 DOI: 10.1016/j.bbrc.2005.05.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2005] [Accepted: 05/06/2005] [Indexed: 10/25/2022]
Abstract
The G alpha subunits of the G12 family of heterotrimeric G proteins, G alpha12 and G alpha13, are closely related in sequences and some effectors, but they often act through different pathways or bind to different proteins. We have examined subcellular distribution of these two G proteins and found that endogenous G alpha12 and G alpha13 localize in membrane and cytoplasmic fractions, respectively. Exogenously expressed G alpha12 and G alpha13 also localize in membrane and cytoplasmic fractions, respectively, in COS-7 cells. Stimulation of lysophosphatidic acid receptor coupled to G alpha13 markedly promotes the translocation of G alpha13 from cytoplasm to membrane. This different localization of G alpha12 and G alpha13 may explain some of the nonoverlapping actions of G alpha12 and G alpha13.
Collapse
Affiliation(s)
- Junya Yamazaki
- Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | | | | | | |
Collapse
|
48
|
Grabocka E, Wedegaertner PB. Functional consequences of G alpha 13 mutations that disrupt interaction with p115RhoGEF. Oncogene 2005; 24:2155-65. [PMID: 15735747 PMCID: PMC1351220 DOI: 10.1038/sj.onc.1208414] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The G-protein alpha subunit, alpha(13), regulates cell growth and differentiation through the monomeric Rho GTPase. Alpha(13) activates Rho through direct stimulation of the guanine nucleotide exchange factor p115RhoGEF, which contains a regulator of G-protein signaling homology domain (RH) in its N-terminus. Through its RH domain, p115RhoGEF also functions as a GAP for G alpha(13). The mechanism for the G alpha(13)/p115RhoGEF interaction is not well understood. Here, we determined specific alpha(13) residues important for its interaction with p115RhoGEF. GST-pulldowns and co-immunoprecipitation assays revealed that individually mutating alpha(13) residues Lys204, Glu229, or Arg232 to opposite charge residues disrupts the interaction of activated alpha(13) with the RH domain of p115RhoGEF or full-length p115RhoGEF. We further demonstrate that mutation of Glu229, and to a lesser extent Lys204 or Arg232, disrupts the ability of activated alpha(13) to induce the recruitment of p115RhoGEF to the plasma membrane (PM) and to activate Rho-mediated serum response element-luciferase gene transcription. Interestingly, an alpha(13) mutant where a conserved Gly was mutated to a Ser (G205S) retained its ability to bind to p115RhoGEF, induce p115RhoGEF recruitment to the PM, and activate Rho-dependent signaling, even though identical Gly to Ser mutations in other alpha disrupt their interaction with regulator of G-protein signaling (RGS) proteins. These results demonstrate that, whereas several features of a typical alpha/RGS interaction are preserved in the alpha(13)/p115RhoGEF interaction, there are also significant differences.
Collapse
Affiliation(s)
| | - Philip B. Wedegaertner
- Corresponding address: Philip Wedegaertner, Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, 233 S. 10 St., 839 BLSB, Philadelphia, PA 19107, tel: 215-503-3137, fax: 215-923-2117, e-mail:
| |
Collapse
|
49
|
Nakayamada S, Kurose H, Saito K, Mogami A, Tanaka Y. Small GTP-binding protein Rho-mediated signaling promotes proliferation of rheumatoid synovial fibroblasts. Arthritis Res Ther 2005; 7:R476-84. [PMID: 15899034 PMCID: PMC1174939 DOI: 10.1186/ar1694] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2004] [Revised: 01/10/2005] [Accepted: 01/18/2005] [Indexed: 11/21/2022] Open
Abstract
Rho is a major small GTP-binding protein that is involved in the regulation of various cell functions, including proliferation and cell migration, through activation of multiple signaling molecules in various types of cells. We studied its roles in synovial fibroblasts (SFs) in patients with rheumatoid arthritis (RA) and clarified its relevance to RA synovitis, with the following results. 1)We found that the thrombin receptor was overexpressed on RA synovial fibroblasts (RA SFs) and that thrombin induced a marked proliferation and progression of the cell cycle to the S phase in these cells. 2)We also found that thrombin efficiently activated Rho. 3)Rho activation and proliferation and the progression of the cell cycle to the S phase were completely blocked by p115RGS (an N-terminal regulator of the G-protein signaling domain of p115RhoGEF) and by the C-terminal fragments of Gα13 (an inhibitor of the interaction of receptors with G13). 4)Thrombin induced the secretion of IL-6 by RA SFs, but this action was blocked by p115RGS or Gα13. Our findings show that the actions of thrombin on the proliferation of RA SFs, cell-cycle progression to the S phase, and IL-6 secretion were mainly mediated by the G13 and RhoGEF pathways. These results suggest that p115RGS and Gα13 could be potent inhibitors of such functions. A rational design of future therapeutic strategies for RA synovitis could perhaps include the exploitation of the Rho pathway to directly reduce the growth of synovial cells.
Collapse
Affiliation(s)
- Shingo Nakayamada
- First Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Fukuoka, Japan
| | - Hitoshi Kurose
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Kazuyoshi Saito
- First Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Fukuoka, Japan
| | - Akira Mogami
- Pharmaceuticals Research Unit, Research & Development Division, Mitsubishi Pharma Corporation, Yokohama, Japan
| | - Yoshiya Tanaka
- First Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Fukuoka, Japan
| |
Collapse
|
50
|
Vázquez-Prado J, Miyazaki H, Castellone MD, Teramoto H, Gutkind JS. Chimeric G alpha i2/G alpha 13 proteins reveal the structural requirements for the binding and activation of the RGS-like (RGL)-containing Rho guanine nucleotide exchange factors (GEFs) by G alpha 13. J Biol Chem 2004; 279:54283-90. [PMID: 15485891 DOI: 10.1074/jbc.m410594200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The alpha-subunit of G proteins of the G(12/13) family stimulate Rho by their direct binding to the RGS-like (RGL) domain of a family of Rho guanine nucleotide exchange factors (RGL-RhoGEFs) that includes PDZ-RhoGEF (PRG), p115RhoGEF, and LARG, thereby regulating cellular functions as diverse as shape and movement, gene expression, and normal and aberrant cell growth. The structural features determining the ability of G alpha(12/13) to bind RGL domains and the mechanism by which this association results in the activation of RGL-RhoGEFs are still poorly understood. Here, we explored the structural requirements for the functional interaction between G alpha(13) and RGL-RhoGEFs based on the structure of RGL domains and their similarity with the area by which RGS4 binds the switch region of G alpha(i) proteins. Using G alpha(i2), which does not bind RGL domains, as the backbone in which G alpha(13) sequences were swapped or mutated, we observed that the switch region of G alpha(13) is strictly necessary to bind PRG, and specific residues were identified that are critical for this association, likely by contributing to the binding surface. Surprisingly, the switch region of G alpha(13) was not sufficient to bind RGL domains, but instead most of its GTPase domain is required. Furthermore, membrane localization of G alpha(13) and chimeric G alpha(i2) proteins was also necessary for Rho activation. These findings revealed the structural features by which G alpha(13) interacts with RGL domains and suggest that molecular interactions occurring at the level of the plasma membrane are required for the functional activation of the RGL-containing family of RhoGEFs.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Cell Line
- Embryo, Mammalian
- GTP-Binding Protein alpha Subunit, Gi2
- GTP-Binding Protein alpha Subunits, G12-G13/chemistry
- GTP-Binding Protein alpha Subunits, G12-G13/genetics
- GTP-Binding Protein alpha Subunits, G12-G13/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/chemistry
- GTP-Binding Protein alpha Subunits, Gi-Go/genetics
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- Guanine Nucleotide Exchange Factors/chemistry
- Guanine Nucleotide Exchange Factors/metabolism
- Humans
- Kidney
- Mice
- Models, Molecular
- Molecular Sequence Data
- Molecular Structure
- NIH 3T3 Cells
- Point Mutation
- Proto-Oncogene Proteins/chemistry
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/metabolism
- RGS Proteins/chemistry
- RGS Proteins/metabolism
- Receptors, Glutamate/chemistry
- Receptors, Glutamate/metabolism
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/metabolism
- Rho Guanine Nucleotide Exchange Factors
- Structure-Activity Relationship
- Transfection
Collapse
Affiliation(s)
- José Vázquez-Prado
- Oral & Pharyngeal Cancer Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | | | |
Collapse
|