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Duan H, Chen B, Wang W, Luo H. Identification of GNG7 as a novel biomarker and potential therapeutic target for gastric cancer via bioinformatic analysis and in vitro experiments. Aging (Albany NY) 2023; 15:1445-1474. [PMID: 36863706 PMCID: PMC10042700 DOI: 10.18632/aging.204545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 02/16/2023] [Indexed: 03/04/2023]
Abstract
Gastric cancer (GC) is one of the most common malignancies with unfavorable prognoses. The present study aimed to identify novel biomarkers or potential therapeutic targets in GC via bioinformatic analysis and in vitro experiments. The Gene Expression Omnibus and The Cancer Genome Atlas databases were used to screen the differentially expressed genes (DEGs). After protein-protein interaction network construction, both module and prognostic analyses were performed to identify prognosis-related genes in GC. The expression patterns and functions of G protein γ subunit 7 (GNG7) in GC were then visualized in multiple databases and further verified using in vitro experiments. A total of 897 overlapping DEGs were detected and 20 hub genes were identified via systematic analysis. After accessing the prognostic value of the hub genes using the online server Kaplan-Meier plotter, a six-gene prognostic signature was identified, which was also significantly correlated with the process of immune infiltration in GC. The results of open-access database analyses suggested that GNG7 is downregulated in GC; this downregulation was associated with tumor progression. Furthermore, the functional enrichment analysis unveiled that the GNG7-coexpressed genes or gene sets were closely correlated with the proliferation and cell cycle processes of GC cells. Finally, in vitro experiments further confirmed that GNG7 overexpression inhibited GC cell proliferation, colony formation, and cell cycle progression and induced apoptosis. As a tumor suppressor gene, GNG7 suppressed the growth of GC cells via cell cycle blockade and apoptosis induction and thus may be used as a potential biomarker and therapeutic target for GC.
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Affiliation(s)
- Houyu Duan
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei, P.R. China
| | - Biao Chen
- Department of Oncology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei, P.R. China
| | - Wei Wang
- Department of Hepatobiliary Surgery, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei, P.R. China
| | - Hesheng Luo
- Department of Gastroenterology, Renmin Hospital of Wuhan University, Wuhan 430060, Hubei, P.R. China
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2
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Yim YY, McDonald WH, Betke KM, Kaya A, Hyde K, Erreger K, Gilsbach R, Hein L, Hamm HE. Specificities of Gβγ subunits for the SNARE complex before and after stimulation of α 2a-adrenergic receptors. Sci Signal 2021; 14:eabc4970. [PMID: 34932372 DOI: 10.1126/scisignal.abc4970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Ligand binding to G protein–coupled receptors (GPCRs), such as the α2a-adrenergic receptor (α2aAR), results in the activation of heterotrimeric G proteins, which consist of functionally distinct Gα subunits and Gβγ dimers. α2aAR-dependent inhibition of synaptic transmission regulates functions such as spontaneous locomotor activity, anesthetic sparing, and working memory enhancement and requires the soluble NSF attachment protein receptor (SNARE) complex, a Gβγ effector. To understand how the Gβγ-SNARE complex underlies the α2aAR-dependent inhibition of synaptic transmission, we examined the specificity of Gβγ subunits for the SNARE complex in adrenergic neurons, in which auto-α2aARs respond to epinephrine released from these neurons, and nonadrenergic neurons, in which hetero-α2aARs respond to epinephrine released from other neurons. We performed a quantitative, targeted multiple reaction monitoring proteomic analysis of Gβ and Gγ subunits bound to the SNARE complex in synaptosomes from mouse brains. In the absence of stimulation of auto-α2aARs, Gβ1 and Gγ3 interacted with the SNARE complex. However, Gβ1, Gβ2, and Gγ3 were found in the complex when auto-α2aARs were activated by epinephrine. Further understanding of the specific usage of distinct Gβγ subunits in vivo may provide insights into the homeostatic regulation of synaptic transmission and the mechanisms of dysfunction that occur in neurological diseases.
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Affiliation(s)
- Yun Young Yim
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - W Hayes McDonald
- Department of Biochemistry and Mass Spectrometry Research Center, Vanderbilt University, Nashville, TN 37232, USA
| | - Katherine M Betke
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Ali Kaya
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Karren Hyde
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Kevin Erreger
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Ralf Gilsbach
- Fachbereich Medizin, Institute for Cardiovascular Physiology, Goethe University, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Lutz Hein
- Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany
| | - Heidi E Hamm
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
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3
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Zurawski Z, Thompson Gray AD, Brady LJ, Page B, Church E, Harris NA, Dohn MR, Yim YY, Hyde K, Mortlock DP, Jones CK, Winder DG, Alford S, Hamm HE. Disabling the Gβγ-SNARE interaction disrupts GPCR-mediated presynaptic inhibition, leading to physiological and behavioral phenotypes. Sci Signal 2019; 12:12/569/eaat8595. [PMID: 30783011 DOI: 10.1126/scisignal.aat8595] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
G protein-coupled receptors (GPCRs) that couple to Gi/o proteins modulate neurotransmission presynaptically by inhibiting exocytosis. Release of Gβγ subunits from activated G proteins decreases the activity of voltage-gated Ca2+ channels (VGCCs), decreasing excitability. A less understood Gβγ-mediated mechanism downstream of Ca2+ entry is the binding of Gβγ to SNARE complexes, which facilitate the fusion of vesicles with the cell plasma membrane in exocytosis. Here, we generated mice expressing a form of the SNARE protein SNAP25 with premature truncation of the C terminus and that were therefore partially deficient in this interaction. SNAP25Δ3 homozygote mice exhibited normal presynaptic inhibition by GABAB receptors, which inhibit VGCCs, but defective presynaptic inhibition by receptors that work directly on the SNARE complex, such as 5-hydroxytryptamine (serotonin) 5-HT1b receptors and adrenergic α2a receptors. Simultaneously stimulating receptors that act through both mechanisms showed synergistic inhibitory effects. SNAP25Δ3 homozygote mice had various behavioral phenotypes, including increased stress-induced hyperthermia, defective spatial learning, impaired gait, and supraspinal nociception. These data suggest that the inhibition of exocytosis by Gi/o-coupled GPCRs through the Gβγ-SNARE interaction is a crucial component of numerous physiological and behavioral processes.
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Affiliation(s)
- Zack Zurawski
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.,Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | | | - Lillian J Brady
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Brian Page
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Emily Church
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Nicholas A Harris
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Michael R Dohn
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Yun Young Yim
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Karren Hyde
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA
| | - Douglas P Mortlock
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Carrie K Jones
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Danny G Winder
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | - Simon Alford
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Heidi E Hamm
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.
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The in vivo specificity of synaptic Gβ and Gγ subunits to the α 2a adrenergic receptor at CNS synapses. Sci Rep 2019; 9:1718. [PMID: 30737458 PMCID: PMC6368627 DOI: 10.1038/s41598-018-37222-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 11/26/2018] [Indexed: 11/21/2022] Open
Abstract
G proteins are major transducers of signals from G-protein coupled receptors (GPCRs). They are made up of α, β, and γ subunits, with 16 Gα, 5 Gβ and 12 Gγ subunits. Though much is known about the specificity of Gα subunits, the specificity of Gβγs activated by a given GPCR and that activate each effector in vivo is not known. Here, we examined the in vivo Gβγ specificity of presynaptic α2a-adrenergic receptors (α2aARs) in both adrenergic (auto-α2aARs) and non-adrenergic neurons (hetero-α2aARs) for the first time. With a quantitative MRM proteomic analysis of neuronal Gβ and Gγ subunits, and co-immunoprecipitation of tagged α2aARs from mouse models including transgenic FLAG-α2aARs and knock-in HA-α2aARs, we investigated the in vivo specificity of Gβ and Gγ subunits to auto-α2aARs and hetero-α2aARs activated with epinephrine to understand the role of Gβγ specificity in diverse physiological functions such as anesthetic sparing, and working memory enhancement. We detected Gβ2, Gγ2, Gγ3, and Gγ4 with activated auto α2aARs, whereas we found Gβ4 and Gγ12 preferentially interacted with activated hetero-α2aARs. Further understanding of in vivo Gβγ specificity to various GPCRs offers new insights into the multiplicity of genes for Gβ and Gγ, and the mechanisms underlying GPCR signaling through Gβγ subunits.
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5
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Abstract
Modulation of neurotransmitter exocytosis by activated Gi/o coupled G-protein coupled receptors (GPCRs) is a universal regulatory mechanism used both to avoid overstimulation and to influence circuitry. One of the known modulation mechanisms is the interaction between Gβγ and the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNAREs). There are 5 Gβ and 12 Gγ subunits, but specific Gβγs activated by a given GPCR and the specificity to effectors, such as SNARE, in vivo are not known. Although less studied, Gβγ binding to the exocytic fusion machinery (i.e. SNARE) provides a more direct regulatory mechanism for neurotransmitter release. Here, we review some recent insights in the architecture of the synaptic terminal, modulation of synaptic transmission, and implications of G protein modulation of synaptic transmission in diseases. Numerous presynaptic proteins are involved in the architecture of synaptic terminals, particularly the active zone, and their importance in the regulation of exocytosis is still not completely understood. Further understanding of the Gβγ-SNARE interaction and the architecture and mechanisms of exocytosis may lead to the discovery of novel therapeutic targets to help patients with various disorders such as hypertension, attention-deficit/hyperactivity disorder, post-traumatic stress disorder, and acute/chronic pain.
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Affiliation(s)
- Yun Young Yim
- Department of Pharmacology, Vanderbilt University, Nashville 37232-6600, TN, United States
| | - Zack Zurawski
- Department of Pharmacology, Vanderbilt University, Nashville 37232-6600, TN, United States
| | - Heidi Hamm
- Department of Pharmacology, Vanderbilt University, Nashville 37232-6600, TN, United States.
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6
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Daraio T, Valladolid-Acebes I, Brismar K, Bark C. SNAP-25a and SNAP-25b differently mediate interactions with Munc18-1 and Gβγ subunits. Neurosci Lett 2018; 674:75-80. [PMID: 29548989 DOI: 10.1016/j.neulet.2018.03.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 03/09/2018] [Accepted: 03/12/2018] [Indexed: 02/06/2023]
Abstract
SNAP-25 is a protein involved in regulated membrane fusion and part of the SNARE complex. It exists as two splicing variants, SNAP-25a and SNAP-25b, which differ in 9 out of 206 amino acids. SNAP-25 together with Syntaxin 1 and VAMP-2 forms the ternary SNARE complex essential for mediating activity-dependent release of hormones and neurotransmitters. The functional difference between SNAP-25a and SNAP-25b is poorly understood as both can participate in SNARE complexes and mediate membrane fusion. However, we recently demonstrated that SNAP-25b-deficiency results in metabolic disease and increased insulin secretion. Here we investigated if SNAP-25a and SNAP-25b differently affect interactions with other SNAREs and SNARE-interacting proteins in mouse hippocampus. Adult mice almost exclusively express the SNAP-25b protein in hippocampus whereas SNAP-25b-deficient mice only express SNAP-25a. Immunoprecipitation studies showed no significant differences in amount of Syntaxin 1 and VAMP-2 co-precipitated with the different SNAP-25 isoforms. In contrast, Munc18-1, that preferentially interacts with SNAP-25 via Syntaxin 1 and/or the trimeric SNARE complex, demonstrated an increased ability to bind protein-complexes containing SNAP-25b. Moreover, we found that both SNAP-25 isoforms co-precipitated the Gβγ subunits of the heterotrimeric G proteins, an interaction known to play a role in presynaptic inhibition. We have identified Gβ1 and Gβ2 as the interacting partners of both SNAP-25 isoforms in mouse hippocampus, but Gβ2 was less efficiently captured by SNAP-25a. These results implicate that the two SNAP-25 isoforms could differently mediate protein interactions outside the ternary SNARE core complex and thereby contribute to modulate neurotransmission.
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Affiliation(s)
- Teresa Daraio
- Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Ismael Valladolid-Acebes
- Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Kerstin Brismar
- Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-171 76 Stockholm, Sweden
| | - Christina Bark
- Department of Molecular Medicine and Surgery, Karolinska Institutet, SE-171 76 Stockholm, Sweden.
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7
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Manes NP, Nita-Lazar A. Application of targeted mass spectrometry in bottom-up proteomics for systems biology research. J Proteomics 2018; 189:75-90. [PMID: 29452276 DOI: 10.1016/j.jprot.2018.02.008] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 01/25/2018] [Accepted: 02/07/2018] [Indexed: 02/08/2023]
Abstract
The enormous diversity of proteoforms produces tremendous complexity within cellular proteomes, facilitates intricate networks of molecular interactions, and constitutes a formidable analytical challenge for biomedical researchers. Currently, quantitative whole-proteome profiling often relies on non-targeted liquid chromatography-mass spectrometry (LC-MS), which samples proteoforms broadly, but can suffer from lower accuracy, sensitivity, and reproducibility compared with targeted LC-MS. Recent advances in bottom-up proteomics using targeted LC-MS have enabled previously unachievable identification and quantification of target proteins and posttranslational modifications within complex samples. Consequently, targeted LC-MS is rapidly advancing biomedical research, especially systems biology research in diverse areas that include proteogenomics, interactomics, kinomics, and biological pathway modeling. With the recent development of targeted LC-MS assays for nearly the entire human proteome, targeted LC-MS is positioned to enable quantitative proteomic profiling of unprecedented quality and accessibility to support fundamental and clinical research. Here we review recent applications of bottom-up proteomics using targeted LC-MS for systems biology research. SIGNIFICANCE: Advances in targeted proteomics are rapidly advancing systems biology research. Recent applications include systems-level investigations focused on posttranslational modifications (such as phosphoproteomics), protein conformation, protein-protein interaction, kinomics, proteogenomics, and metabolic and signaling pathways. Notably, absolute quantification of metabolic and signaling pathway proteins has enabled accurate pathway modeling and engineering. Integration of targeted proteomics with other technologies, such as RNA-seq, has facilitated diverse research such as the identification of hundreds of "missing" human proteins (genes and transcripts that appear to encode proteins but direct experimental evidence was lacking).
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Affiliation(s)
- Nathan P Manes
- Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Aleksandra Nita-Lazar
- Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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8
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Yim YY, McDonald WH, Hyde K, Cruz-Rodríguez O, Tesmer JJG, Hamm HE. Quantitative Multiple-Reaction Monitoring Proteomic Analysis of Gβ and Gγ Subunits in C57Bl6/J Brain Synaptosomes. Biochemistry 2017; 56:5405-5416. [PMID: 28880079 DOI: 10.1021/acs.biochem.7b00433] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Gβγ dimers are one of the essential signaling units of activated G protein-coupled receptors (GPCRs). There are five Gβ and 12 Gγ subunits in humans; numerous studies have demonstrated that different Gβ and Gγ subunits selectively interact to form unique Gβγ dimers, which in turn may target specific receptors and effectors. Perturbation of Gβγ signaling can lead to impaired physiological responses. Moreover, previous targeted multiple-reaction monitoring (MRM) studies of Gβ and Gγ subunits have shown distinct regional and subcellular localization patterns in four brain regions. Nevertheless, no studies have quantified or compared their individual protein levels. In this study, we have developed a quantitative MRM method not only to quantify but also to compare the protein abundance of neuronal Gβ and Gγ subunits. In whole and fractionated crude synaptosomes, we were able to identify the most abundant neuronal Gβ and Gγ subunits and their subcellular localizations. For example, Gβ1 was mostly localized at the membrane while Gβ2 was evenly distributed throughout synaptosomal fractions. The protein expression levels and subcellular localizations of Gβ and Gγ subunits may affect the Gβγ dimerization and Gβγ-effector interactions. This study offers not only a new tool for quantifying and comparing Gβ and Gγ subunits but also new insights into the in vivo distribution of Gβ and Gγ subunits, and Gβγ dimer assembly in normal brain function.
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Affiliation(s)
- Yun Young Yim
- Department of Pharmacology, Vanderbilt University , Nashville, Tennessee 37232-6600, United States
| | - W Hayes McDonald
- Department of Biochemistry, Vanderbilt University , Nashville, Tennessee 37232-6600, United States
| | - Karren Hyde
- Department of Pharmacology, Vanderbilt University , Nashville, Tennessee 37232-6600, United States
| | | | | | - Heidi E Hamm
- Department of Pharmacology, Vanderbilt University , Nashville, Tennessee 37232-6600, United States
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10
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Chen M, Liu S, Li W, Zhang Z, Zhang X, Zhang XE, Cui Z. Three-Fragment Fluorescence Complementation Coupled with Photoactivated Localization Microscopy for Nanoscale Imaging of Ternary Complexes. ACS NANO 2016; 10:8482-8490. [PMID: 27584616 DOI: 10.1021/acsnano.6b03543] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Many cellular processes are governed by molecular machineries that involve multiple protein interactions. However, visualizing and identifying multiprotein complexes such as ternary complexes inside cells is always challenging, particularly in the subdiffraction cellular space. Here, we developed a three-fragment fluorescence complementation system (TFFC) based on the splitting of a photoactivatable fluorescent protein, mIrisFP, for the imaging of ternary complexes inside living cells. Using a combination of TFFC and photoactivated localization microscopy (PALM), namely, the TFFC-PALM technique, we are able to identify the multi-interaction of a ternary complex with nanometer-level spatial resolution and single-molecule sensitivity. The TFFC-PALM system has been further applied to the analysis of the Gs ternary complex, which is composed of αs, β1, and γ2 subunits, providing further insights into the subcellular localization and function of G protein subunits at the single-molecule level. The TFFC-PALM represents a valuable method for the visualization and identification of ternary complexes inside cells at the nanometer scale.
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Affiliation(s)
- Minghai Chen
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, China
- University of Chinese Academy of Sciences , Beijing 100049, China
| | - Sanying Liu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, China
- University of Chinese Academy of Sciences , Beijing 100049, China
| | - Wei Li
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, China
| | - Zhiping Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, China
| | - Xiaowei Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, China
| | - Xian-En Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences , Beijing 100101, China
| | - Zongqiang Cui
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, China
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11
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Liu J, Ji X, Li Z, Yang X, Wang W, Zhang X. G protein γ subunit 7 induces autophagy and inhibits cell division. Oncotarget 2016; 7:24832-47. [PMID: 27056891 PMCID: PMC5029746 DOI: 10.18632/oncotarget.8559] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 02/28/2016] [Indexed: 11/25/2022] Open
Abstract
GNG7 (G protein γ subunit 7), a subunit of heterotrimeric G protein, is ubiquitously expressed in multiple tissues but is down-regulated in various cancers. Its expression could reduce tumor volume in mice but the mechanism was not clear. Here we show that GNG7 overexpression inhibits cell proliferation and increases cell death. GNG7 level is cell cycle-dependent and it regulates actin cytoskeleton and cell division. In addition, GNG7 is an autophagy inducer, which is the first reported Gγ protein involved in autophagy. GNG7 knockdown reduces Rapamycin and starvation-induced autophagy. Further analysis reveals that GNG7 inhibits MTOR in cells, a central regulator for autophagy and cell proliferation. In conclusion, GNG7 inhibits MTOR pathway to induce autophagy and cell death, inhibits cell division by regulating actin cytoskeleton. These combined effects lead to the antitumor capacity of GNG7.
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Affiliation(s)
- Juanjuan Liu
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China
- University of Science and Technology of China, Hefei, Anhui, 230036, P. R. China
| | - Xinmiao Ji
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China
| | - Zhiyuan Li
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China
| | - Xingxing Yang
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China
| | - Wenchao Wang
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China
| | - Xin Zhang
- High Magnetic Field Laboratory, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China
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12
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Zurawski Z, Rodriguez S, Hyde K, Alford S, Hamm HE. Gβγ Binds to the Extreme C Terminus of SNAP25 to Mediate the Action of Gi/o-Coupled G Protein-Coupled Receptors. Mol Pharmacol 2015; 89:75-83. [PMID: 26519224 DOI: 10.1124/mol.115.101600] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 10/30/2015] [Indexed: 11/22/2022] Open
Abstract
Gi/o-coupled G protein-coupled receptors can exert an inhibitory effect on vesicle release through several G protein-driven mechanisms, more than one of which may be concurrently present in individual presynaptic terminals. The synaptosomal-associated protein of 25 kDa (SNAP25) is a key downstream effector of Gβγ subunits. It has previously been shown that proteolytic cleavage of SNAP25 by botulinum toxin A reduces the ability of Gβγ to compete with the calcium sensor synaptotagmin 1 (Syt1) for binding to SNAP25 in a calcium-dependent manner. These truncated SNAP25 proteins sustain a low level of exocytosis but are unable to support serotonin-mediated inhibition of exocytosis in lamprey spinal neurons. Here, we generate a SNAP25 extreme C-terminal mutant that is deficient in its ability to bind Gβγ while retaining normal calcium-dependent Syt1 binding to soluble N-ethylmaleimide attachment protein receptor (SNARE) and vesicle release. The SNAP25Δ3 mutant, in which residue G204 is replaced by a stop codon, features a partial reduction in Gβ1γ2 binding in vitro as well as a partial reduction in the ability of the lamprey 5-hydroxytryptamine1b-type serotonin receptor to reduce excitatory postsynaptic current amplitudes, an effect previously shown to be mediated through the interaction of Gβγ with SNAP25. Syt1 calcium-dependent binding to SNAP25Δ3 was reduced by a small extent compared with the wild type. We conclude that the extreme C terminus of SNAP25 is a critical region for the Gβγ-SNARE interaction.
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Affiliation(s)
- Zack Zurawski
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (Z.Z., K.H., H.E.H.); and Department of Biological Sciences, University of Illinois, Chicago, Illinois (S.R., S.A.)
| | - Shelagh Rodriguez
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (Z.Z., K.H., H.E.H.); and Department of Biological Sciences, University of Illinois, Chicago, Illinois (S.R., S.A.)
| | - Karren Hyde
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (Z.Z., K.H., H.E.H.); and Department of Biological Sciences, University of Illinois, Chicago, Illinois (S.R., S.A.)
| | - Simon Alford
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (Z.Z., K.H., H.E.H.); and Department of Biological Sciences, University of Illinois, Chicago, Illinois (S.R., S.A.)
| | - Heidi E Hamm
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee (Z.Z., K.H., H.E.H.); and Department of Biological Sciences, University of Illinois, Chicago, Illinois (S.R., S.A.)
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13
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Pierce MR, Raj A, Betke KM, Zeidan LN, Matthies HJG, May JM. Sodium-dependent vitamin C transporter-2 mediates vitamin C transport at the cortical nerve terminal. J Neurosci Res 2015; 93:1881-90. [PMID: 26366722 DOI: 10.1002/jnr.23669] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 08/04/2015] [Accepted: 08/31/2015] [Indexed: 11/09/2022]
Abstract
It has been shown that vitamin C (VC) is transported at synaptic boutons, but how this occurs has not been elucidated. This study investigates the role of the sodium-dependent vitamin C transporter-2 (SVCT2) in transporting VC at the cortical nerve terminal. Immunostaining of cultured mouse superior cervical ganglion cells showed the SVCT2 to be expressed in presynaptic boutons, colocalizing with the vesicular monoamine transporter-2 and the norepinephrine transporter. Immunoblotting of enriched cortical synaptosomes demonstrated that the SVCT2 was enriched in presynaptic fractions, confirming a predominantly presynaptic location. In crude synaptosomes, known inhibitors of SVCT2 inhibited uptake of VC. Furthermore, the kinetic features of VC uptake were consistent with SVCT2-mediated function. VC was also found to efflux from synaptosomes by a mechanism not involving the SVCT2. Indeed, VC efflux was substantially offset by reuptake of VC on the SVCT2. The presence and function of the SVCT2 at the presynaptic nerve terminal suggest that it is the transporter responsible for recovery of VC released into the synaptic cleft.
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Affiliation(s)
- Marquicia R Pierce
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Amita Raj
- Department of Neuroscience, Vanderbilt University, Nashville, Tennessee
| | - Katherine M Betke
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - L Nora Zeidan
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
| | - Heinrich J G Matthies
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - James M May
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
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Ebhardt HA, Root A, Sander C, Aebersold R. Applications of targeted proteomics in systems biology and translational medicine. Proteomics 2015; 15:3193-208. [PMID: 26097198 PMCID: PMC4758406 DOI: 10.1002/pmic.201500004] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 04/27/2015] [Accepted: 06/09/2015] [Indexed: 01/28/2023]
Abstract
Biological systems are composed of numerous components of which proteins are of particularly high functional significance. Network models are useful abstractions for studying these components in context. Network representations display molecules as nodes and their interactions as edges. Because they are difficult to directly measure, functional edges are frequently inferred from suitably structured datasets consisting of the accurate and consistent quantification of network nodes under a multitude of perturbed conditions. For the precise quantification of a finite list of proteins across a wide range of samples, targeted proteomics exemplified by selected/multiple reaction monitoring (SRM, MRM) mass spectrometry has proven useful and has been applied to a variety of questions in systems biology and clinical studies. Here, we survey the literature of studies using SRM-MS in systems biology and clinical proteomics. Systems biology studies frequently examine fundamental questions in network biology, whereas clinical studies frequently focus on biomarker discovery and validation in a variety of diseases including cardiovascular disease and cancer. Targeted proteomics promises to advance our understanding of biological networks and the phenotypic significance of specific network states and to advance biomarkers into clinical use.
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Affiliation(s)
- H Alexander Ebhardt
- Department of Biology, Institute of Molecular Systems Biology, Eidgenossische Technische Hochschule (ETH) Zurich, Zurich, Switzerland
| | - Alex Root
- Computational Biology Center, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
- Department of Physiology, Biophysics and Systems Biology, Weill Cornell Medical College, New York, NY, USA
| | - Chris Sander
- Computational Biology Center, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
| | - Ruedi Aebersold
- Department of Biology, Institute of Molecular Systems Biology, Eidgenossische Technische Hochschule (ETH) Zurich, Zurich, Switzerland
- Faculty of Science, University of Zurich, Zurich, Switzerland
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