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Xiao N, Xie Z, He Z, Xu Y, Zhen S, Wei Y, Zhang X, Shen J, Wang J, Tian Y, Zuo J, Peng J, Li Z. Pathogenesis of gout: Exploring more therapeutic target. Int J Rheum Dis 2024; 27:e15147. [PMID: 38644732 DOI: 10.1111/1756-185x.15147] [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: 12/02/2023] [Revised: 03/28/2024] [Accepted: 03/30/2024] [Indexed: 04/23/2024]
Abstract
Gout is a chronic metabolic and immune disease, and its specific pathogenesis is still unclear. When the serum uric acid exceeds its saturation in the blood or tissue fluid, it is converted to monosodium urate crystals, which lead to acute arthritis of varying degrees, urinary stones, or irreversible peripheral joint damage, and in severe cases, impairment of vital organ function. Gout flare is a clinically significant state of acute inflammation in gout. The current treatment is mostly anti-inflammatory analgesics, which have numerous side effects with limited treatment methods. Gout pathogenesis involves many aspects. Therefore, exploring gout pathogenesis from multiple perspectives is conducive to identifying more therapeutic targets and providing safer and more effective alternative treatment options for patients with gout flare. Thus, this article is of great significance for further exploring the pathogenesis of gout. The author summarizes the pathogenesis of gout from four aspects: signaling pathways, inflammatory factors, intestinal flora, and programmed cell death, focusing on exploring more new therapeutic targets.
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Affiliation(s)
- Niqin Xiao
- First Clinical Medical College, Yunnan University of Chinese Medicine, Kunming, China
| | - Zhaohu Xie
- School of Basic Medical Sciences, Yunnan University of Chinese Medicine, Kunming, China
| | - Zhiyan He
- First Clinical Medical College, Yunnan University of Chinese Medicine, Kunming, China
| | - Yundong Xu
- First Clinical Medical College, Yunnan University of Chinese Medicine, Kunming, China
| | - Shuyu Zhen
- First Clinical Medical College, Yunnan University of Chinese Medicine, Kunming, China
| | - Yuanyuan Wei
- First Clinical Medical College, Yunnan University of Chinese Medicine, Kunming, China
| | - Xiaoyu Zhang
- First Clinical Medical College, Yunnan University of Chinese Medicine, Kunming, China
| | - Jiayan Shen
- First Clinical Medical College, Yunnan University of Chinese Medicine, Kunming, China
| | - Jian Wang
- First Clinical Medical College, Yunnan University of Chinese Medicine, Kunming, China
| | - Yadan Tian
- First Clinical Medical College, Yunnan University of Chinese Medicine, Kunming, China
| | - Jinlian Zuo
- First Clinical Medical College, Yunnan University of Chinese Medicine, Kunming, China
| | - Jiangyun Peng
- The First Affiliated Hospital of Yunnan University of Traditional Chinese Medicine, Kunming, China
| | - Zhaofu Li
- Yunnan University of Chinese Medicine, Kunming, China
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Wang Y, Wang T, Han Z, Wang R, Hu Y, Yang Z, Shen T, Zheng Y, Luo J, Ma Y, Luo Y, Jiao L. Explore the role of long noncoding RNAs and mRNAs in intracranial atherosclerotic stenosis: From the perspective of neutrophils. Brain Circ 2023; 9:240-250. [PMID: 38284107 PMCID: PMC10821680 DOI: 10.4103/bc.bc_63_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 09/22/2023] [Accepted: 09/26/2023] [Indexed: 01/30/2024] Open
Abstract
CONTEXT Circulating neutrophils and long noncoding RNAs (lncRNAs) play various roles in intracranial atherosclerotic stenosis (ICAS). OBJECTIVE Our study aimed to detect differentially expressed (DE) lncRNAs and mRNAs in circulating neutrophils and explore the pathogenesis of atherosclerosis from the perspective of neutrophils. METHODS Nineteen patients with ICAS and 15 healthy controls were enrolled. The peripheral blood of the participants was collected, and neutrophils were separated. The expression profiles of lncRNAs and mRNAs in neutrophils from five patients and five healthy controls were obtained, and DE lncRNAs and mRNAs were selected. Six lncRNAs were selected and validated using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and ceRNA and lncRNA-RNA binding protein (RBP)-mRNA networks were constructed. Correlation analysis between lncRNAs and mRNAs was performed. Functional enrichment annotations were also performed. RESULTS Volcano plots and heat maps displayed the expression profiles and DE lncRNAs and mRNAs, respectively. The qRT-PCR results revealed that the four lncRNAs showed a tendency consistent with the expression profile, with statistical significance. The ceRNA network revealed three pairs of regulatory networks: lncRNA RP3-406A7.3-NAGLU, lncRNA HOTAIRM1-MVK/IL-25/GBF1/CNOT4/ANKK1/PLEKHG6, and lncRNA RP11-701H16.4-ZNF416. The lncRNA-RBP-mRNA network showed five pairs of regulatory networks: lncRNA RP11-701H16.4-TEK, lncRNA RP11-701H16.4-MED17, lncRNA SNHG19-NADH-ubiquinone oxidoreductase core subunit V1, lncRNA RP3-406A7.3-Angel1, and lncRNA HOTAIRM1-CARD16. CONCLUSIONS Our study identified and verified four lncRNAs in neutrophils derived from peripheral blood, which may explain the transcriptional alteration of neutrophils during the pathophysiological process of ICAS. Our results provide insights for research related to the pathogenic mechanisms and drug design of ICAS.
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Affiliation(s)
- Yilin Wang
- Institute of Cerebrovascular Disease Research, Xuanwu Hospital of Capital Medical University, Beijing, China
| | - Tao Wang
- Department of Neurosurgery, Xuanwu Hospital of Capital Medical University, Beijing, China
| | - Ziping Han
- Institute of Cerebrovascular Disease Research, Xuanwu Hospital of Capital Medical University, Beijing, China
| | - Rongliang Wang
- Institute of Cerebrovascular Disease Research, Xuanwu Hospital of Capital Medical University, Beijing, China
| | - Yue Hu
- Institute of Cerebrovascular Disease Research, Xuanwu Hospital of Capital Medical University, Beijing, China
| | - Zhenhong Yang
- Institute of Cerebrovascular Disease Research, Xuanwu Hospital of Capital Medical University, Beijing, China
| | - Tong Shen
- Institute of Cerebrovascular Disease Research, Xuanwu Hospital of Capital Medical University, Beijing, China
| | - Yangmin Zheng
- Institute of Cerebrovascular Disease Research, Xuanwu Hospital of Capital Medical University, Beijing, China
| | - Jichang Luo
- Department of Neurosurgery, Xuanwu Hospital of Capital Medical University, Beijing, China
- Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
| | - Yan Ma
- Department of Neurosurgery, Xuanwu Hospital of Capital Medical University, Beijing, China
- Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
| | - Yumin Luo
- Institute of Cerebrovascular Disease Research, Xuanwu Hospital of Capital Medical University, Beijing, China
- Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
- Beijing Geriatric Medical Research Center, Beijing Key Laboratory of Translational Medicine for Cerebrovascular Diseases, Beijing, China
| | - Liqun Jiao
- Department of Neurosurgery, Xuanwu Hospital of Capital Medical University, Beijing, China
- Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
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Meissner JM, Akhmetova K, Szul T, Viktorova EG, Sha B, Bhatt JM, Lee EJ, Kahn RA, Belov GA, Chesnokov I, Sztul E. The Arf-GEF GBF1 undergoes multi-domain structural shifts to activate Arf at the Golgi. Front Cell Dev Biol 2023; 11:1233272. [PMID: 37745300 PMCID: PMC10512945 DOI: 10.3389/fcell.2023.1233272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 08/29/2023] [Indexed: 09/26/2023] Open
Abstract
Golgi homeostasis require the activation of Arf GTPases by the guanine-nucleotide exchange factor requires GBF1, whose recruitment to the Golgi represents a rate limiting step in the process. GBF1 contains a conserved, catalytic, Sec7 domain (Sec7d) and five additional (DCB, HUS, HDS1-3) domains. Herein, we identify the HDS3 domain as essential for GBF1 membrane association in mammalian cells and document the critical role of HDS3 during the development of Drosophila melanogaster. We show that upon binding to Golgi membranes, GBF1 undergoes conformational changes in regions bracketing the catalytic Sec7d. We illuminate GBF1 interdomain arrangements by negative staining electron microscopy of full-length human GBF1 to show that GBF1 forms an anti-parallel dimer held together by the paired central DCB-HUS core, with two sets of HDS1-3 arms extending outward in opposite directions. The catalytic Sec7d protrudes from the central core as a largely independent domain, but is closely opposed to a previously unassigned α-helix from the HDS1 domain. Based on our data, we propose models of GBF1 engagement on the membrane to provide a paradigm for understanding GBF1-mediated Arf activation required for cellular and organismal function.
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Affiliation(s)
- Justyna M. Meissner
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Katarina Akhmetova
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Tomasz Szul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Ekaterina G. Viktorova
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD, United States
| | - Bingdong Sha
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Jay M. Bhatt
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Eunjoo J. Lee
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Richard A. Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, United States
| | - George A. Belov
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD, United States
| | - Igor Chesnokov
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, United States
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4
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Walton K, Nawara TJ, Angermeier AR, Rosengrant H, Lee E, Wynn B, Victorova E, Belov G, Sztul E. Site-specific phosphorylations of the Arf activator GBF1 differentially regulate GBF1 function in Golgi homeostasis and secretion versus cytokinesis. Sci Rep 2023; 13:13609. [PMID: 37604968 PMCID: PMC10442430 DOI: 10.1038/s41598-023-40705-5] [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: 10/13/2022] [Accepted: 08/16/2023] [Indexed: 08/23/2023] Open
Abstract
Diverse cellular processes, including membrane traffic, lipid homeostasis, cytokinesis, mitochondrial positioning, and cell motility are critically dependent on the Sec7 domain guanine nucleotide exchange factor GBF1. Yet, how the participation of GBF1 in a particular cellular function is regulated is unknown. Here, we show that the phosphorylation of specific highly conserved serine and tyrosine residues within the N-terminal domain of GBF1 differentially regulates its function in maintaining Golgi homeostasis and facilitating secretion versus its role in cytokinesis. Specifically, GBF1 mutants containing single amino acid substitutions that mimic a stably phosphorylated S233, S371, Y377, and Y515 or the S233A mutant that can't be phosphorylated are fully able to maintain Golgi architecture and support cargo traffic through the secretory pathway when assessed in multiple functional assays. However, the same mutants cause multi-nucleation when expressed in cells, and appear to inhibit the progression through mitosis and the resolution of cytokinetic bridges. Thus, GBF1 participates in distinct interactive networks when mediating Golgi homeostasis and secretion versus facilitating cytokinesis, and GBF1 integration into such networks is differentially regulated by the phosphorylation of specific GBF1 residues.
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Affiliation(s)
- Kendall Walton
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA.
| | - Tomasz J Nawara
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Allyson R Angermeier
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Hadley Rosengrant
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Eunjoo Lee
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Bridge Wynn
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
| | - Ekaterina Victorova
- Department of Veterinary Medicine, Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, MD, 20742, USA
| | - George Belov
- Department of Veterinary Medicine, Virginia-Maryland College of Veterinary Medicine, University of Maryland, College Park, MD, 20742, USA
| | - Elizabeth Sztul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, 1918 University Boulevard, MCLM 668, Birmingham, AL, 35233-2008, USA
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5
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Xiong W, Jia L, Liang J, Cai Y, Chen Y, Nie Y, Jin J, Zhu J. Investigation into the anti-airway inflammatory role of the PI3Kγ inhibitor JN-PK1: An in vitro and in vivo study. Int Immunopharmacol 2022; 111:109102. [PMID: 35964410 DOI: 10.1016/j.intimp.2022.109102] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 07/16/2022] [Accepted: 07/25/2022] [Indexed: 12/17/2022]
Abstract
Phosphatidylinositol 3-kinase gamma (PI3Kγ) has been proven to be a potential target for the treatment of inflammatory diseases of the airway; however, there are few reports of selective PI3Kγ inhibitors being used in the field of airway inflammation thus far. Herein, a study employing in vitro and in vivo methodologies was carried out to assess the anti-airway inflammatory effects of JN-PK1, a selective PI3Kγ inhibitor. In RAW264.7 macrophages, JN-PK1 inhibited PI3Kγ-dependent, cellular C5a-induced AKT Ser473 phosphorylation in a concentration- and time-dependent manner and had no significant effect on cell viability.Furthermore, JN-PK1 significantly suppressed LPS-induced, proinflammatory cytokine expression and nitric oxide production through inhibition of the PI3K signaling pathway in RAW264.7 cells. Then, a murine asthma model was established to evaluate the anti-airway inflammation effect of JN-PK1. BALB/c mice were sensitized and challenged with ovalbumin (OVA) to develop an inflammatory response, fibrosis formation, and other airway changes similar to the symptomatology of asthma in humans. Oral administration of JN-PK1 remarkably attenuated OVA-induced asthma in association with the inhibition of the PI3K signaling pathway. That is to say, the oral administration significantly inhibited increases in inflammatory cell counts and reduced T-helper type 2 cytokine production in bronchoalveolar lavage fluid. Pulmonary histological studies showed that oral administration of JN-PK1 not only reduced the infiltration of inflammatory cells but also retarded airway inflammation and fibration. Taken together, JN-PK1 could be developed as a promising candidate for inflammation therapy, and our findings support some potential for therapeutic inhibition of PI3Kγ to treat inflammatory airway diseases.
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Affiliation(s)
- Wendian Xiong
- School of Life Sciences and Health Engineering, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Lei Jia
- School of Life Sciences and Health Engineering, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Junjie Liang
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Yanfei Cai
- School of Life Sciences and Health Engineering, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Yun Chen
- School of Life Sciences and Health Engineering, Jiangnan University, Wuxi, Jiangsu 214122, China
| | - Yunjuan Nie
- Department of Basic Medicine, Wuxi School of Medicine, Jiangnan University, Wuxi, Jiangsu 214122, China.
| | - Jian Jin
- School of Life Sciences and Health Engineering, Jiangnan University, Wuxi, Jiangsu 214122, China.
| | - Jingyu Zhu
- School of Life Sciences and Health Engineering, Jiangnan University, Wuxi, Jiangsu 214122, China.
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6
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Klemm LC, Denu RA, Hind LE, Rocha-Gregg BL, Burkard ME, Huttenlocher A. Centriole and Golgi microtubule nucleation are dispensable for the migration of human neutrophil-like cells. Mol Biol Cell 2021; 32:1545-1556. [PMID: 34191538 PMCID: PMC8351748 DOI: 10.1091/mbc.e21-02-0060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 05/27/2021] [Accepted: 06/11/2021] [Indexed: 11/19/2022] Open
Abstract
Neutrophils migrate in response to chemoattractants to mediate host defense. Chemoattractants drive rapid intracellular cytoskeletal rearrangements including the radiation of microtubules from the microtubule-organizing center (MTOC) toward the rear of polarized neutrophils. Microtubules regulate neutrophil polarity and motility, but little is known about the specific role of MTOCs. To characterize the role of MTOCs on neutrophil motility, we depleted centrioles in a well-established neutrophil-like cell line. Surprisingly, both chemical and genetic centriole depletion increased neutrophil speed and chemotactic motility, suggesting an inhibitory role for centrioles during directed migration. We also found that depletion of both centrioles and GM130-mediated Golgi microtubule nucleation did not impair neutrophil directed migration. Taken together, our findings demonstrate an inhibitory role for centrioles and a resilient MTOC system in motile human neutrophil-like cells.
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Affiliation(s)
- Lucas C. Klemm
- Molecular and Cellular Pharmacology Graduate Training Program, University of Wisconsin-Madison, Madison, WI 53706
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706
| | - Ryan A. Denu
- Medical Scientist Training Program, University of Wisconsin-Madison, Madison, WI 53706
- Department of Medicine, Division of Hematology/Oncology, University of Wisconsin-Madison, Madison, WI 53706
| | - Laurel E. Hind
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706
| | - Briana L. Rocha-Gregg
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706
| | - Mark E. Burkard
- Department of Medicine, Division of Hematology/Oncology, University of Wisconsin-Madison, Madison, WI 53706
| | - Anna Huttenlocher
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53706
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7
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Unconventional p97/VCP-Mediated Endoplasmic Reticulum-to-Endosome Trafficking of a Retroviral Protein. J Virol 2021; 95:e0053121. [PMID: 33952644 DOI: 10.1128/jvi.00531-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Mouse mammary tumor virus (MMTV) encodes a Rem precursor protein that specifies both regulatory and accessory functions. Rem is cleaved at the endoplasmic reticulum (ER) membrane into a functional N-terminal signal peptide (SP) and the C terminus (Rem-CT). Rem-CT lacks a membrane-spanning domain and a known ER retention signal, and yet it was not detectably secreted into cell supernatants. Inhibition of intracellular trafficking by the drug brefeldin A (BFA), which interferes with the ER-to-Golgi secretory pathway, resulted in dramatically reduced intracellular Rem-CT levels that were not rescued by proteasomal or lysosomal inhibitors. A Rem mutant lacking glycosylation was cleaved into SP and Rem-CT but was insensitive to BFA, suggesting that unglycosylated Rem-CT does not reach this BFA-dependent compartment. Treatment with endoglycosidase H indicated that Rem-CT does not traffic through the Golgi apparatus. Analysis of wild-type Rem-CT and its glycosylation mutant by confocal microscopy revealed that both were primarily localized to the ER lumen. A small fraction of wild-type Rem-CT, but not the unglycosylated mutant, was colocalized with Rab5-positive (Rab5+) early endosomes. The expression of a dominant-negative (DN) form of ADP ribosylation factor 1 (Arf1) (containing a mutation of threonine to asparagine at position 31 [T31N]) mimicked the effects of BFA by reducing Rem-CT levels and increased Rem-CT association with early and late endosomes. Inhibition of the AAA ATPase p97/VCP rescued Rem-CT in the presence of BFA or DN Arf1 and prevented localization to Rab5+ endosomes. Thus, Rem-CT uses an unconventional p97-mediated scheme for trafficking to early endosomes. IMPORTANCE Mouse mammary tumor virus is a complex retrovirus that encodes a regulatory/accessory protein, Rem. Rem is a precursor protein that is processed at the endoplasmic reticulum (ER) membrane by signal peptidase. The N-terminal SP uses the p97/VCP ATPase to elude ER-associated degradation to traffic to the nucleus and serve a human immunodeficiency virus Rev-like function. In contrast, the function of the C-terminal glycosylated cleavage product (Rem-CT) is unknown. Since localization is critical for protein function, we used mutants, inhibitors, and confocal microscopy to localize Rem-CT. Surprisingly, Rem-CT, which lacks a transmembrane domain or an ER retention signal, was detected primarily within the ER and required glycosylation and the p97 ATPase for early endosome trafficking without passage through the Golgi apparatus. Thus, Rem-CT uses a novel intracellular trafficking pathway, potentially impacting host antiviral immunity.
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8
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Khater M, Bryant CN, Wu G. Gβγ translocation to the Golgi apparatus activates ARF1 to spatiotemporally regulate G protein-coupled receptor signaling to MAPK. J Biol Chem 2021; 296:100805. [PMID: 34022220 PMCID: PMC8215300 DOI: 10.1016/j.jbc.2021.100805] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/11/2021] [Accepted: 05/18/2021] [Indexed: 01/01/2023] Open
Abstract
After activation of G protein-coupled receptors, G protein βγ dimers may translocate from the plasma membrane to the Golgi apparatus (GA). We recently report that this translocation activates extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) via PI3Kγ; however, how Gβγ-PI3Kγ activates the ERK1/2 pathway is unclear. Here, we demonstrate that chemokine receptor CXCR4 activates ADP-ribosylation factor 1 (ARF1), a small GTPase important for vesicle-mediated membrane trafficking. This activation is blocked by CRISPR-Cas9-mediated knockout of the GA-translocating Gγ9 subunit. Inducible targeting of different Gβγ dimers to the GA can directly activate ARF1. CXCR4 activation and constitutive Gβγ recruitment to the GA also enhance ARF1 translocation to the GA. We further demonstrate that pharmacological inhibition and CRISPR-Cas9-mediated knockout of PI3Kγ markedly inhibit CXCR4-mediated and Gβγ translocation-mediated ARF1 activation. We also show that depletion of ARF1 by siRNA and CRISPR-Cas9 and inhibition of GA-localized ARF1 activation abolish ERK1/2 activation by CXCR4 and Gβγ translocation to the GA and suppress prostate cancer PC3 cell migration and invasion. Collectively, our data reveal a novel function for Gβγ translocation to the GA to activate ARF1 and identify GA-localized ARF1 as an effector acting downstream of Gβγ-PI3Kγ to spatiotemporally regulate G protein-coupled receptor signaling to mitogen-activated protein kinases.
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Affiliation(s)
- Mostafa Khater
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Christian N Bryant
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Guangyu Wu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, Georgia, USA.
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9
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Montaño-Rendón F, Grinstein S, Walpole GFW. Monitoring Phosphoinositide Fluxes and Effectors During Leukocyte Chemotaxis and Phagocytosis. Front Cell Dev Biol 2021; 9:626136. [PMID: 33614656 PMCID: PMC7890364 DOI: 10.3389/fcell.2021.626136] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 01/06/2021] [Indexed: 01/22/2023] Open
Abstract
The dynamic re-organization of cellular membranes in response to extracellular stimuli is fundamental to the cell physiology of myeloid and lymphoid cells of the immune system. In addition to maintaining cellular homeostatic functions, remodeling of the plasmalemma and endomembranes endow leukocytes with the potential to relay extracellular signals across their biological membranes to promote rolling adhesion and diapedesis, migration into the tissue parenchyma, and to ingest foreign particles and effete cells. Phosphoinositides, signaling lipids that control the interface of biological membranes with the external environment, are pivotal to this wealth of functions. Here, we highlight the complex metabolic transitions that occur to phosphoinositides during several stages of the leukocyte lifecycle, namely diapedesis, migration, and phagocytosis. We describe classical and recently developed tools that have aided our understanding of these complex lipids. Finally, major downstream effectors of inositides are highlighted including the cytoskeleton, emphasizing the importance of these rare lipids in immunity and disease.
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Affiliation(s)
- Fernando Montaño-Rendón
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada.,Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON, Canada
| | - Glenn F W Walpole
- Program in Cell Biology, Hospital for Sick Children, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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10
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Walton K, Leier A, Sztul E. Regulating the regulators: role of phosphorylation in modulating the function of the GBF1/BIG family of Sec7 ARF-GEFs. FEBS Lett 2020; 594:2213-2226. [PMID: 32333796 DOI: 10.1002/1873-3468.13798] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 04/15/2020] [Accepted: 04/16/2020] [Indexed: 12/15/2022]
Abstract
Membrane traffic between secretory and endosomal compartments is vesicle-mediated and must be tightly balanced to maintain a physiological compartment size. Vesicle formation is initiated by guanine nucleotide exchange factors (GEFs) that activate the ARF family of small GTPases. Regulatory mechanisms, including reversible phosphorylation, allow ARF-GEFs to support vesicle formation only at the right time and place in response to cellular needs. Here, we review current knowledge of how the Golgi-specific brefeldin A-resistance factor 1 (GBF1)/brefeldin A-inhibited guanine nucleotide exchange protein (BIG) family of ARF-GEFs is influenced by phosphorylation and use predictive paradigms to propose new regulatory paradigms. We describe a conserved cluster of phosphorylation sites within the N-terminal domains of the GBF1/BIG ARF-GEFs and suggest that these sites may respond to homeostatic signals related to cell growth and division. In the C-terminal region, GBF1 shows phosphorylation sites clustered differently as compared with the similar configuration found in both BIG1 and BIG2. Despite this similarity, BIG1 and BIG2 phosphorylation patterns are divergent in other domains. The different clustering of phosphorylation sites suggests that the nonconserved sites may represent distinct regulatory nodes and specify the function of GBF1, BIG1, and BIG2.
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Affiliation(s)
- Kendall Walton
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, AL, USA
| | - Andre Leier
- Department of Genetics, University of Alabama at Birmingham, AL, USA
| | - Elizabeth Sztul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, AL, USA
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11
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Assessment of Arf6 Deletion in PLB-985 Differentiated in Neutrophil-Like Cells and in Mouse Neutrophils: Impact on Adhesion and Migration. Mediators Inflamm 2020; 2020:2713074. [PMID: 32322163 PMCID: PMC7166286 DOI: 10.1155/2020/2713074] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 03/24/2020] [Indexed: 12/12/2022] Open
Abstract
Chemoattractant sensing, adhesiveness, and migration are critical events underlying the recruitment of neutrophils (PMNs) to sites of inflammation or infection. Defects in leukocyte adhesion or migration result in immunodeficiency disorders characterized by recurrent infections. In this study, we evaluated the role of Arf6 on PMN adhesion in vitro and on migration to inflammatory sites using PMN-Arf6 conditional knockout (cKO) mice. In PMN-like PLB-985 silenced for Arf6 fMLP-mediated adhesion to the β2 integrin ligands, ICAM-1 and fibrinogen or the β1/β2 integrin ligand fibronectin was significantly reduced. Furthermore, overexpression of wild-type Arf6 promoted basal and fMLP-induced adhesion to immobilized integrin ligands, while overexpression of the dominant-negative Arf6 has the opposite effects. Using the Elane-Cre deleting mouse strains, we report that the level of Arf6 deletion in inflammatory PMNs isolated from the dorsal air pouches was stronger when compared to naïve cells isolated from the bone marrow. In PMN-Arf6 cKO mice, the recruitment of PMNs into the dorsal air pouch injected with LPS or the chemoattractant fMLP was significantly diminished. Impaired cell migration correlated with reduced cell surface expression of CD11a and CD11b in Arf6 cKO PMNs. Our results highlight that Arf6 regulates the activity and possibly the recycling of PMN integrins, and this compromises PMN migration to inflammatory sites.
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12
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Thottacherry JJ, Sathe M, Prabhakara C, Mayor S. Spoiled for Choice: Diverse Endocytic Pathways Function at the Cell Surface. Annu Rev Cell Dev Biol 2019; 35:55-84. [PMID: 31283376 PMCID: PMC6917507 DOI: 10.1146/annurev-cellbio-100617-062710] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Endocytosis has long been identified as a key cellular process involved in bringing in nutrients, in clearing cellular debris in tissue, in the regulation of signaling, and in maintaining cell membrane compositional homeostasis. While clathrin-mediated endocytosis has been most extensively studied, a number of clathrin-independent endocytic pathways are continuing to be delineated. Here we provide a current survey of the different types of endocytic pathways available at the cell surface and discuss a new classification and plausible molecular mechanisms for some of the less characterized pathways. Along with an evolutionary perspective of the origins of some of these pathways, we provide an appreciation of the distinct roles that these pathways play in various aspects of cellular physiology, including the control of signaling and membrane tension.
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Affiliation(s)
- Joseph Jose Thottacherry
- National Centre for Biological Science, Tata Institute for Fundamental Research, Bangalore 560065, India;
| | - Mugdha Sathe
- National Centre for Biological Science, Tata Institute for Fundamental Research, Bangalore 560065, India;
| | - Chaitra Prabhakara
- National Centre for Biological Science, Tata Institute for Fundamental Research, Bangalore 560065, India;
| | - Satyajit Mayor
- National Centre for Biological Science, Tata Institute for Fundamental Research, Bangalore 560065, India;
- Institute for Stem Cell Science and Regenerative Medicine, Bangalore, 560065, India
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13
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Saraste J, Prydz K. A New Look at the Functional Organization of the Golgi Ribbon. Front Cell Dev Biol 2019; 7:171. [PMID: 31497600 PMCID: PMC6713163 DOI: 10.3389/fcell.2019.00171] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 08/07/2019] [Indexed: 12/14/2022] Open
Abstract
A characteristic feature of vertebrate cells is a Golgi ribbon consisting of multiple cisternal stacks connected into a single-copy organelle next to the centrosome. Despite numerous studies, the mechanisms that link the stacks together and the functional significance of ribbon formation remain poorly understood. Nevertheless, these questions are of considerable interest, since there is increasing evidence that Golgi fragmentation – the unlinking of the stacks in the ribbon – is intimately connected not only to normal physiological processes, such as cell division and migration, but also to pathological states, including neurodegeneration and cancer. Challenging a commonly held view that ribbon architecture involves the formation of homotypic tubular bridges between the Golgi stacks, we present an alternative model, based on direct interaction between the biosynthetic (pre-Golgi) and endocytic (post-Golgi) membrane networks and their connection with the centrosome. We propose that the central domains of these permanent pre- and post-Golgi networks function together in the biogenesis and maintenance of the more transient Golgi stacks, and thereby establish “linker compartments” that dynamically join the stacks together. This model provides insight into the reversible fragmentation of the Golgi ribbon that takes place in dividing and migrating cells and its regulation along a cell surface – Golgi – centrosome axis. Moreover, it helps to understand transport pathways that either traverse or bypass the Golgi stacks and the positioning of the Golgi apparatus in differentiated neuronal, epithelial, and muscle cells.
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Affiliation(s)
- Jaakko Saraste
- Department of Biomedicine and Molecular Imaging Center, University of Bergen, Bergen, Norway
| | - Kristian Prydz
- Department of Biosciences, University of Oslo, Oslo, Norway
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14
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Sztul E, Chen PW, Casanova JE, Cherfils J, Dacks JB, Lambright DG, Lee FJS, Randazzo PA, Santy LC, Schürmann A, Wilhelmi I, Yohe ME, Kahn RA. ARF GTPases and their GEFs and GAPs: concepts and challenges. Mol Biol Cell 2019; 30:1249-1271. [PMID: 31084567 PMCID: PMC6724607 DOI: 10.1091/mbc.e18-12-0820] [Citation(s) in RCA: 143] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 02/26/2019] [Accepted: 03/11/2019] [Indexed: 12/12/2022] Open
Abstract
Detailed structural, biochemical, cell biological, and genetic studies of any gene/protein are required to develop models of its actions in cells. Studying a protein family in the aggregate yields additional information, as one can include analyses of their coevolution, acquisition or loss of functionalities, structural pliability, and the emergence of shared or variations in molecular mechanisms. An even richer understanding of cell biology can be achieved through evaluating functionally linked protein families. In this review, we summarize current knowledge of three protein families: the ARF GTPases, the guanine nucleotide exchange factors (ARF GEFs) that activate them, and the GTPase-activating proteins (ARF GAPs) that have the ability to both propagate and terminate signaling. However, despite decades of scrutiny, our understanding of how these essential proteins function in cells remains fragmentary. We believe that the inherent complexity of ARF signaling and its regulation by GEFs and GAPs will require the concerted effort of many laboratories working together, ideally within a consortium to optimally pool information and resources. The collaborative study of these three functionally connected families (≥70 mammalian genes) will yield transformative insights into regulation of cell signaling.
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Affiliation(s)
- Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Pei-Wen Chen
- Department of Biology, Williams College, Williamstown, MA 01267
| | - James E. Casanova
- Department of Cell Biology, University of Virginia, Charlottesville, VA 22908
| | - Jacqueline Cherfils
- Laboratoire de Biologie et Pharmacologie Appliquée, CNRS and Ecole Normale Supérieure Paris-Saclay, 94235 Cachan, France
| | - Joel B. Dacks
- Division of Infectious Disease, Department of Medicine, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - David G. Lambright
- Program in Molecular Medicine and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Amherst, MA 01605
| | - Fang-Jen S. Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan
| | | | - Lorraine C. Santy
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802
| | - Annette Schürmann
- German Institute of Human Nutrition, 85764 Potsdam-Rehbrücke, Germany
| | - Ilka Wilhelmi
- German Institute of Human Nutrition, 85764 Potsdam-Rehbrücke, Germany
| | - Marielle E. Yohe
- Pediatric Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892
| | - Richard A. Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322-3050
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15
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Lopes-da-Silva M, McCormack JJ, Burden JJ, Harrison-Lavoie KJ, Ferraro F, Cutler DF. A GBF1-Dependent Mechanism for Environmentally Responsive Regulation of ER-Golgi Transport. Dev Cell 2019; 49:786-801.e6. [PMID: 31056345 PMCID: PMC6764485 DOI: 10.1016/j.devcel.2019.04.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 02/19/2019] [Accepted: 04/04/2019] [Indexed: 12/17/2022]
Abstract
How can anterograde membrane trafficking be modulated by physiological cues? A screen of Golgi-associated proteins revealed that the ARF-GEF GBF1 can selectively modulate the ER-Golgi trafficking of prohaemostatic von Willebrand factor (VWF) and extracellular matrix (ECM) proteins in human endothelial cells and in mouse fibroblasts. The relationship between levels of GBF1 and the trafficking of VWF into forming secretory granules confirmed GBF1 is a limiting factor in this process. Further, GBF1 activation by AMPK couples its control of anterograde trafficking to physiological cues; levels of glucose control GBF1 activation in turn modulating VWF trafficking into secretory granules. GBF1 modulates both ER and TGN exit, the latter dramatically affecting the size of the VWF storage organelles, thereby influencing the hemostatic capacity of the endothelium. The role of AMPK as a central integrating element of cellular pathways with intra- and extra-cellular cues can now be extended to modulation of the anterograde secretory pathway. The Arf-GEF GBF1 modulates anterograde trafficking of VWF and ECM proteins Loss of GBF1 slows ER and TGN exit, producing swollen ER and giant WPBs Activation of GBF1 via AMPK reduces endothelial WPB size and secretion Metabolic change alters anterograde trafficking and cargo secretion via AMPK-GBF1
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Affiliation(s)
- Mafalda Lopes-da-Silva
- Endothelial Cell Biology Laboratory, MRC Laboratory for Molecular Cell Biology, University College London, London, UK.
| | - Jessica J McCormack
- Endothelial Cell Biology Laboratory, MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Jemima J Burden
- Electron Microscopy Laboratory, MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Kimberly J Harrison-Lavoie
- Endothelial Cell Biology Laboratory, MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Francesco Ferraro
- Endothelial Cell Biology Laboratory, MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Daniel F Cutler
- Endothelial Cell Biology Laboratory, MRC Laboratory for Molecular Cell Biology, University College London, London, UK.
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16
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Mazaki Y, Takada S, Nio-Kobayashi J, Maekawa S, Higashi T, Onodera Y, Sabe H. Mitofusin 2 is involved in chemotaxis of neutrophil-like differentiated HL-60 cells. Biochem Biophys Res Commun 2019; 513:708-713. [PMID: 30987827 DOI: 10.1016/j.bbrc.2019.04.037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 04/04/2019] [Indexed: 02/05/2023]
Abstract
Neutrophils rapidly migrate to infection sites after the recognition of invaders. During chemotaxis, neutrophils require energy supplied by mitochondria oxidative phosphorylation (OXPHOS), whereas neutrophils rely heavily on glycolysis under normal conditions. Mitochondrial OXPHOS correlates with mitochondrial morphology. Here, we examined the mitochondrial morphology of neutrophil-like differentiated HL-60 cells after chemoattractant N-formyl-Met-Leu-Phe (fMLP) stimulation. We found that mitochondrial morphology changes to a tubular form after fMLP stimulation. Mitochondrial OXPHOS activity and mitochondrial complex II significantly increased after fMLP stimulation. On the other hand, the silencing of mitochondrial fusion protein mitofusin 2 (MFN2) suppresses mitochondrial morphological changes. Furthermore, MFN2 silencing suppressed OXPHOS activation and chemotaxis after fMLP stimulation. These results suggest that MFN2 is involved in chemotaxis of differentiated HL-60 cells depending on mitochondria.
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Affiliation(s)
- Yuichi Mazaki
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan.
| | - Shingo Takada
- Department of Cardiovascular Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Junko Nio-Kobayashi
- Laboratory of Histology and Cytology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Satoshi Maekawa
- Department of Cardiovascular Medicine, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Tsunehito Higashi
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Yasuhito Onodera
- Department of Molecular Biology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Hisataka Sabe
- Department of Molecular Biology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
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17
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Annexin A2 is involved in activation of extracellular signal-regulated kinase upon endothelin-1 stimulation. Biochem Biophys Res Commun 2019; 511:69-72. [PMID: 30771901 DOI: 10.1016/j.bbrc.2019.02.040] [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: 02/02/2019] [Accepted: 02/08/2019] [Indexed: 11/20/2022]
Abstract
The overexpression of endothelin (ET)-1 or ET receptors (ETRs) is related to initiation and progression of tumor. In cancer cells, ET-1 activates various signaling pathways, including mitogen-activated protein kinase, phosphatidylinositol 3-kinase, protein kinase C through ETRs, although the mechanisms by which ET-1 activates these signaling pathways remain uncertain. Here, we found that ETRs interacted with annexin A2, which is overexpressed in various cancers. Annexin A2 bound to ET type A receptor and ET type B receptor. Upon ET-1 stimulation, serine phosphorylation of annexin A2 increased, while there is no change in tyrosine phosphorylation of annexin A2. On the other hand, annexin A2 silencing suppressed activation of ERK upon ET-1 stimulation. These results suggest that interaction of ETRs and annexin A2 may play important roles in activation of extracellular signal-regulated kinase upon ET-1 stimulation.
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18
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Mazaki Y, Higashi T, Onodera Y, Nam JM, Hashimoto A, Hashimoto S, Horinouchi T, Miwa S. Endothelin type B receptor interacts with the 78-kDa glucose-regulated protein. FEBS Lett 2019; 593:644-651. [PMID: 30801683 DOI: 10.1002/1873-3468.13347] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 02/13/2019] [Accepted: 02/19/2019] [Indexed: 12/21/2022]
Abstract
Endothelin (ET)-1 is involved in the vascular system, cell proliferation and apoptosis. ET receptors consist of ET type A receptor (ETA R) and ET type B receptor (ETB R). ETA R and ETB R generally exhibit opposite responses, although many exceptions exist. In the present study, we attempted to identify ETA R- or ETB R-specific binding proteins to understand the differences in ETA R- and ETB R-mediated responses after ET-1 stimulation. The 78-kDa glucose-regulated protein (GRP78) showed a stronger binding affinity towards ETB R than towards ETA R. Moreover, GRP78 overexpression promoted ETB R-mediated ERK activation and GRP78 silencing suppressed ETB R-mediated ERK activation. Furthermore, ETB R can localize GRP78 to the cell periphery. These results suggest that the interaction of ETB R with GRP78 affects ERK activation and GRP78 localization.
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Affiliation(s)
- Yuichi Mazaki
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Tsunehito Higashi
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Yasuhito Onodera
- Department of Molecular Biology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Jin-Min Nam
- GSQ, GI-CoRE, Hokkaido University, Sapporo, Japan
| | - Ari Hashimoto
- Department of Molecular Biology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Shigeru Hashimoto
- Laboratory of Immune Regulation, Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Takahiro Horinouchi
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Soichi Miwa
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
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19
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Collier PN, Panchagnula A, O’Dowd H, Le Tiran A, Aronov AM. Synthesis of a 6-Aza-Isoindolinone-Based Inhibitor of Phosphoinositide 3-Kinase γ via Ruthenium-Catalyzed [2 + 2 + 2] Cyclotrimerization. ACS Med Chem Lett 2019; 10:117-120. [PMID: 30655957 DOI: 10.1021/acsmedchemlett.8b00530] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 11/29/2018] [Indexed: 12/18/2022] Open
Abstract
Phosphoinositide 3-kinase (PI3Kγ) is a drug target that has been implicated in the treatment of a range of diseases. We have developed a synthesis of a novel PI3Kγ inhibitor containing a 1,2-dihydro-3H-pyrrolo[3,4-c]pyridin-3-one scaffold. The key step in the synthesis involved a ruthenium-catalyzed [2 + 2 + 2] cyclotrimerization reaction between a diyne and an alkoxycarbonyl isocyanate, a previously unreported coupling partner in such a reaction.
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Affiliation(s)
- Philip N. Collier
- Vertex Pharmaceuticals Incorporated, 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Advaita Panchagnula
- Vertex Pharmaceuticals Incorporated, 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Hardwin O’Dowd
- Vertex Pharmaceuticals Incorporated, 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Arnaud Le Tiran
- Vertex Pharmaceuticals Incorporated, 50 Northern Avenue, Boston, Massachusetts 02210, United States
| | - Alex M. Aronov
- Vertex Pharmaceuticals Incorporated, 50 Northern Avenue, Boston, Massachusetts 02210, United States
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20
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Pendleton AL, Shen F, Taravella AM, Emery S, Veeramah KR, Boyko AR, Kidd JM. Comparison of village dog and wolf genomes highlights the role of the neural crest in dog domestication. BMC Biol 2018; 16:64. [PMID: 29950181 PMCID: PMC6022502 DOI: 10.1186/s12915-018-0535-2] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 05/23/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Domesticated from gray wolves between 10 and 40 kya in Eurasia, dogs display a vast array of phenotypes that differ from their ancestors, yet mirror other domesticated animal species, a phenomenon known as the domestication syndrome. Here, we use signatures persisting in dog genomes to identify genes and pathways possibly altered by the selective pressures of domestication. RESULTS Whole-genome SNP analyses of 43 globally distributed village dogs and 10 wolves differentiated signatures resulting from domestication rather than breed formation. We identified 246 candidate domestication regions containing 10.8 Mb of genome sequence and 429 genes. The regions share haplotypes with ancient dogs, suggesting that the detected signals are not the result of recent selection. Gene enrichments highlight numerous genes linked to neural crest and central nervous system development as well as neurological function. Read depth analysis suggests that copy number variation played a minor role in dog domestication. CONCLUSIONS Our results identify genes that act early in embryogenesis and can confer phenotypes distinguishing domesticated dogs from wolves, such as tameness, smaller jaws, floppy ears, and diminished craniofacial development as the targets of selection during domestication. These differences reflect the phenotypes of the domestication syndrome, which can be explained by alterations in the migration or activity of neural crest cells during development. We propose that initial selection during early dog domestication was for behavior, a trait influenced by genes which act in the neural crest, which secondarily gave rise to the phenotypes of modern dogs.
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Affiliation(s)
- Amanda L Pendleton
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Feichen Shen
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Angela M Taravella
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Sarah Emery
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Krishna R Veeramah
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Adam R Boyko
- Department of Biomedical Sciences, Cornell University, Ithaca, New York, 14853, USA
| | - Jeffrey M Kidd
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, 48109, USA.
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, 48109, USA.
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21
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Come JH, Collier PN, Henderson JA, Pierce AC, Davies RJ, Le Tiran A, O'Dowd H, Bandarage UK, Cao J, Deininger D, Grey R, Krueger EB, Lowe DB, Liang J, Liao Y, Messersmith D, Nanthakumar S, Sizensky E, Wang J, Xu J, Chin EY, Damagnez V, Doran JD, Dworakowski W, Griffith JP, Jacobs MD, Khare-Pandit S, Mahajan S, Moody CS, Aronov AM. Design and Synthesis of a Novel Series of Orally Bioavailable, CNS-Penetrant, Isoform Selective Phosphoinositide 3-Kinase γ (PI3Kγ) Inhibitors with Potential for the Treatment of Multiple Sclerosis (MS). J Med Chem 2018; 61:5245-5256. [PMID: 29847724 DOI: 10.1021/acs.jmedchem.8b00085] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The lipid kinase phosphoinositide 3-kinase γ (PI3Kγ) has attracted attention as a potential target to treat a variety of autoimmune disorders, including multiple sclerosis, due to its role in immune modulation and microglial activation. By minimizing the number of hydrogen bond donors while targeting a previously uncovered selectivity pocket adjacent to the ATP binding site of PI3Kγ, we discovered a series of azaisoindolinones as selective, brain penetrant inhibitors of PI3Kγ. This ultimately led to the discovery of 16, an orally bioavailable compound that showed efficacy in murine experimental autoimmune encephalomyelitis (EAE), a preclinical model of multiple sclerosis.
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Affiliation(s)
- Jon H Come
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Philip N Collier
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - James A Henderson
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Albert C Pierce
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Robert J Davies
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Arnaud Le Tiran
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Hardwin O'Dowd
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Upul K Bandarage
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Jingrong Cao
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - David Deininger
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Ron Grey
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Elaine B Krueger
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Derek B Lowe
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Jianglin Liang
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Yusheng Liao
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - David Messersmith
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Suganthi Nanthakumar
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Emmanuelle Sizensky
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Jian Wang
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Jinwang Xu
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Elaine Y Chin
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Veronique Damagnez
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - John D Doran
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Wojciech Dworakowski
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - James P Griffith
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Marc D Jacobs
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Suvarna Khare-Pandit
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Sudipta Mahajan
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Cameron S Moody
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
| | - Alex M Aronov
- Vertex Pharmaceuticals Incorporated , 50 Northern Avenue , Boston , Massachusetts 02210 , United States
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22
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Cui Z, Zeng Q, Guo Y, Liu S, Chen J. Integrated bioinformatic changes and analysis of retina with time in diabetic rats. PeerJ 2018; 6:e4762. [PMID: 29785346 PMCID: PMC5960260 DOI: 10.7717/peerj.4762] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 04/23/2018] [Indexed: 01/22/2023] Open
Abstract
Diabetic retinopathy (DR) is the most common chronic complication of diabetes. It can cause impaired vision and even blindness. However, the pathological mechanism of DR is still unknown. In the present study, we use bioinformatic analysis to reveal the pathological changes of early DR in a streptozotocin (STZ) induced diabetes rat model. The dataset GSE28831 was downloaded from the Gene Expression Omnibus (GEO) database. To clarify the pathological mechanism of early DR, genes which were up-regulated (UP group) or down-regulated (DOWN group) over time were identified. One hundred eighty six genes in the UP group and 85 genes in the DOWN group were defined. There were in total 28 Gene ontology (GO) terms with a P value lower than 0.05 in UP group, including astrocyte development, neutrophil chemotaxis, neutrophil aggregation, mesenchymal cell proliferation and so on. In the DOWN group, there were totally 14 GO terms with a P value lower than 0.05, including visual perception, lens development in camera-type eye, camera-type eye development, bicellular tight junction and so on. Signaling pathways were analyzed with all genes in the UP and DOWN groups, and leukocyte transendothelial migration and tight junction were selected. Protein–protein interaction (PPI) network was constructed and six hub genes Diras3, Actn1, Tssk6, Cnot6l, Tek and Fgf4 were selected with connection degree ≥5. S100a8, S100a9 and Tek may be potential targets for DR diagnosis and treatment. This study provides the basis for the diagnosis and treatment of DR in the future.
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Affiliation(s)
- Zekai Cui
- Key Laboratory for Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China
| | - Qiaolang Zeng
- The Department of Ophthalmology, The First Clinical Medical College, Jinan University, Guangzhou, China
| | - Yonglong Guo
- Key Laboratory for Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China
| | - Shiwei Liu
- The Department of Ophthalmology, The First Clinical Medical College, Jinan University, Guangzhou, China
| | - Jiansu Chen
- Key Laboratory for Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, China.,The Department of Ophthalmology, The First Clinical Medical College, Jinan University, Guangzhou, China.,Institute of Ophthalmology, Medical College, Jinan University, Guangzhou, China.,Aier Eye Institute, Changsha, China
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23
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Pocognoni CA, Viktorova EG, Wright J, Meissner JM, Sager G, Lee E, Belov GA, Sztul E. Highly conserved motifs within the large Sec7 ARF guanine nucleotide exchange factor GBF1 target it to the Golgi and are critical for GBF1 activity. Am J Physiol Cell Physiol 2018; 314:C675-C689. [PMID: 29443553 DOI: 10.1152/ajpcell.00221.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cellular life requires the activation of the ADP-ribosylation factors (ARFs) by Golgi brefeldin A-resistant factor 1 (GBF1), a guanine nucleotide exchange factor (GEF) with a highly conserved catalytic Sec7 domain (Sec7d). In addition to the Sec7d, GBF1 contains other conserved domains whose functions remain unclear. Here, we focus on HDS2 (homology downstream of Sec7d 2) domain because the L1246R substitution within the HDS2 α-helix 5 of the zebrafish GBF1 ortholog causes vascular hemorrhaging and embryonic lethality (13). To dissect the structure/function relationships within HDS2, we generated six variants, in which the most conserved residues within α-helices 1, 2, 4, and 6 were mutated to alanines. Each HDS2 mutant was assessed in a cell-based "replacement" assay for its ability to support cellular functions normally supported by GBF1, such as maintaining Golgi homeostasis, facilitating COPI recruitment, supporting secretion, and sustaining cellular viability. We show that cells treated with the pharmacological GBF1 inhibitor brefeldin A (BFA) and expressing a BFA-resistant GBF1 variant with alanine substitutions of RDR1168 or LF1266 are compromised in Golgi homeostasis, impaired in ARF activation, unable to sustain secretion, and defective in maintaining cellular viability. To gain insight into the molecular mechanism of this dysfunction, we assessed the ability of each GBF1 mutant to target to Golgi membranes and found that mutations in RDR1168 and LF1266 significantly decrease targeting efficiency. Thus, these residues within α-helix 2 and α-helix 6 of the HDS2 domain in GBF1 are novel regulatory determinants that support GBF1 cellular function by impacting the Golgi-specific membrane association of GBF1.
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Affiliation(s)
- Cristian A Pocognoni
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama
| | - Ekaterina G Viktorova
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland , College Park, Maryland
| | - John Wright
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama
| | - Justyna M Meissner
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama
| | - Garrett Sager
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama
| | - Eunjoo Lee
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama
| | - George A Belov
- Department of Veterinary Medicine, Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland , College Park, Maryland
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama
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24
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Meissner JM, Bhatt JM, Lee E, Styers ML, Ivanova AA, Kahn RA, Sztul E. The ARF guanine nucleotide exchange factor GBF1 is targeted to Golgi membranes through a PIP-binding domain. J Cell Sci 2018; 131:jcs.210245. [PMID: 29361542 DOI: 10.1242/jcs.210245] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 12/15/2017] [Indexed: 11/20/2022] Open
Abstract
ADP-ribosylation factors (ARF) GTPases are activated by guanine nucleotide exchange factors (GEFs) to support cellular homeostasis. Key to understanding spatio-temporal regulation of ARF signaling is the mechanism of GEF recruitment to membranes. Small GEFs are recruited through phosphoinositide (PIP) binding by a pleckstrin homology (PH) domain downstream from the catalytic Sec7 domain (Sec7d). The large GEFs lack PH domains, and their recruitment mechanisms are poorly understood. We probed Golgi recruitment of GBF1, a GEF catalyzing ARF activation required for Golgi homeostasis. We show that the homology downstream of Sec7d-1 (HDS1) regulates Golgi recruitment of GBF1. We document that GBF1 binds phosphoinositides, preferentially PI3P, PI4P and PI(4,5)P2, and that lipid binding requires the HDS1 domain. Mutations within HDS1 that reduce GBF1 binding to specific PIPs in vitro inhibit GBF1 targeting to Golgi membranes in cells. Our data imply that HDS1 and PH domains are functionally analogous in that each uses lipid-based membrane information to regulate GEF recruitment. Lipid-based recruitment of GBF1 extends the paradigm of lipid regulation to small and large GEFs and suggests that lipid-based mechanisms evolved early during GEF diversification. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Justyna M Meissner
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jay M Bhatt
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Eunjoo Lee
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Melanie L Styers
- Department of Biology, Birmingham-Southern College, Birmingham, AL 35254, USA
| | - Anna A Ivanova
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Richard A Kahn
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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25
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ARF1 promotes prostate tumorigenesis via targeting oncogenic MAPK signaling. Oncotarget 2018; 7:39834-39845. [PMID: 27213581 PMCID: PMC5129974 DOI: 10.18632/oncotarget.9405] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 03/11/2016] [Indexed: 11/25/2022] Open
Abstract
ADP-ribosylation factor 1 (ARF1) is a crucial regulator in vesicle-mediated membrane trafficking and involved in the activation of signaling molecules. However, virtually nothing is known about its function in prostate cancer. Here we have demonstrated that ARF1 expression is significantly elevated in prostate cancer cells and human tissues and that the expression levels of ARF1 correlate with the activation of mitogen-activated protein kinases (MAPK) ERK1/2. Furthermore, we have shown that overexpression and knockdown of ARF1 produce opposing effects on prostate cancer cell proliferation, anchorage-independent growth and tumor growth in mouse xenograft models and that ARF1-mediated cell proliferation can be abolished by the Raf1 inhibitor GW5074 and the MEK inhibitors U0126 and PD98059. Moreover, inhibition of ARF1 activation achieved by mutating Thr48 abolishes ARF1's abilities to activate the ERK1/2 and to promote cell proliferation. These data demonstrate that the aberrant MAPK signaling in prostate cancer is, at least in part, under the control of ARF1 and that, similar to Ras, ARF1 is a critical regulator in prostate cancer progression. These data also suggest that ARF1 may represent a key molecular target for prostate cancer therapeutics and diagnosis.
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26
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Kaczmarek B, Verbavatz JM, Jackson CL. GBF1 and Arf1 function in vesicular trafficking, lipid homoeostasis and organelle dynamics. Biol Cell 2017; 109:391-399. [PMID: 28985001 DOI: 10.1111/boc.201700042] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/22/2017] [Accepted: 09/25/2017] [Indexed: 01/07/2023]
Abstract
The ADP-ribosylation factor (Arf) small G proteins act as molecular switches to coordinate multiple downstream pathways that regulate membrane dynamics. Their activation is spatially and temporally controlled by the guanine nucleotide exchange factors (GEFs). Members of the evolutionarily conserved GBF/Gea family of Arf GEFs are well known for their roles in formation of coat protein complex I (COPI) vesicles, essential for maintaining the structure and function of the Golgi apparatus. However, studies over the past 10 years have found new functions for these GEFs, along with their substrate Arf1, in lipid droplet metabolism, clathrin-independent endocytosis, signalling at the plasma membrane, mitochondrial dynamics and transport along microtubules. Here, we describe these different functions, focussing in particular on the emerging theme of GFB1 and Arf1 regulation of organelle movement on microtubules.
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Affiliation(s)
- Beata Kaczmarek
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Paris, F-75013, France
| | - Jean-Marc Verbavatz
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Paris, F-75013, France
| | - Catherine L Jackson
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Paris, F-75013, France
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Mazaki Y, Onodera Y, Higashi T, Horinouchi T, Oikawa T, Sabe H. ARF1 recruits RAC1 to leading edge in neutrophil chemotaxis. Cell Commun Signal 2017; 15:36. [PMID: 28969640 PMCID: PMC5625764 DOI: 10.1186/s12964-017-0193-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 09/22/2017] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The small GTPase ARF1 mediates membrane trafficking mostly from the Golgi, and is essential for the G protein-coupled receptor (GPCR)-mediated chemotaxis of neutrophils. In this process, ARF1 is activated by the guanine nucleotide exchanger GBF1, and is inactivated by the GTPase-activating protein GIT2. Neutrophils generate the Gβγ-PAK1-αPIX-GIT2 linear complex during GPCR-induced chemotaxis, in which αPIX activates RAC1/CDC42, which then employs PAK1. However, it has remained unclear as to why GIT2 is included in this complex. RESULTS We investigated the association between ARF1 and RAC1/CDC42 during the fMLP-stimulated chemotaxis of HL60 cells. We found that the silencing of GBF1 significantly impaired the recruitment of RAC1 to the leading edges, but not PAK1, αPIX, RAC2, or CDC42. A significant population of RAC1 colocalized with ARF1 at the leading edges in stimulated cells, whereas fMLP activated both ARF1 and ARF5. Consistently, the silencing of ARF1, but not ARF5, impaired the recruitment of RAC1, whereas the silencing of RAC1 did not affect the recruitment of ARF1 to the leading edges. CONCLUSIONS Our results indicated that the activation of ARF1 triggers the plasma membrane recruitment of RAC1 in GPCR-mediated chemotaxis, which is essential for cortical actin remodeling. Thus, membrane remodeling at the leading edges appears to precede actin remodeling in chemotaxis. Together with the fact that GIT2, which inactivates ARF1, is an integral component of the machinery activating RAC1, we proposed a model in which the ARF1-RAC1 linkage enables the regulation of ARF1 by repetitive on/off cycles during GPCR-mediated neutrophil chemotaxis.
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Affiliation(s)
- Yuichi Mazaki
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Yasuhito Onodera
- Department of Molecular Biology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Tsunehito Higashi
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Takahiro Horinouchi
- Department of Cellular Pharmacology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Tsukasa Oikawa
- Department of Molecular Biology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Hisataka Sabe
- Department of Molecular Biology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
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28
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Zhou W, Li X, Premont RT. Expanding functions of GIT Arf GTPase-activating proteins, PIX Rho guanine nucleotide exchange factors and GIT-PIX complexes. J Cell Sci 2017; 129:1963-74. [PMID: 27182061 DOI: 10.1242/jcs.179465] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The GIT proteins, GIT1 and GIT2, are GTPase-activating proteins (inactivators) for the ADP-ribosylation factor (Arf) small GTP-binding proteins, and function to limit the activity of Arf proteins. The PIX proteins, α-PIX and β-PIX (also known as ARHGEF6 and ARHGEF7, respectively), are guanine nucleotide exchange factors (activators) for the Rho family small GTP-binding protein family members Rac1 and Cdc42. Through their multi-domain structures, GIT and PIX proteins can also function as signaling scaffolds by binding to numerous protein partners. Importantly, the constitutive association of GIT and PIX proteins into oligomeric GIT-PIX complexes allows these two proteins to function together as subunits of a larger structure that coordinates two distinct small GTP-binding protein pathways and serves as multivalent scaffold for the partners of both constituent subunits. Studies have revealed the involvement of GIT and PIX proteins, and of the GIT-PIX complex, in numerous fundamental cellular processes through a wide variety of mechanisms, pathways and signaling partners. In this Commentary, we discuss recent findings in key physiological systems that exemplify current understanding of the function of this important regulatory complex. Further, we draw attention to gaps in crucial information that remain to be filled to allow a better understanding of the many roles of the GIT-PIX complex in health and disease.
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Affiliation(s)
- Wu Zhou
- Department of Medicine, College of Medicine and Health, Lishui University, Lishui 323000, China
| | - Xiaobo Li
- Department of Computer Science and Technology, College of Engineering and Design, Lishui University, Lishui 323000, China
| | - Richard T Premont
- Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
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29
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Qiao D, Lange C, Beaty TH, Crapo JD, Barnes KC, Bamshad M, Hersh CP, Morrow J, Pinto-Plata VM, Marchetti N, Bueno R, Celli BR, Criner GJ, Silverman EK, Cho MH. Exome Sequencing Analysis in Severe, Early-Onset Chronic Obstructive Pulmonary Disease. Am J Respir Crit Care Med 2017; 193:1353-63. [PMID: 26736064 DOI: 10.1164/rccm.201506-1223oc] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
RATIONALE Genomic regions identified by genome-wide association studies explain only a small fraction of heritability for chronic obstructive pulmonary disease (COPD). Alpha-1 antitrypsin deficiency shows that rare coding variants of large effect also influence COPD susceptibility. We hypothesized that exome sequencing in families identified through a proband with severe, early-onset COPD would identify additional rare genetic determinants of large effect. OBJECTIVES To identify rare genetic determinants of severe COPD. METHODS We applied filtering approaches to identify potential causal variants for COPD in whole exomes from 347 subjects in 49 extended pedigrees from the Boston Early-Onset COPD Study. We assessed the power of this approach under different levels of genetic heterogeneity using simulations. We tested genes identified in these families using gene-based association tests in exomes of 204 cases with severe COPD and 195 resistant smokers from the COPDGene study. In addition, we examined previously described loci associated with COPD using these datasets. MEASUREMENTS AND MAIN RESULTS We identified 69 genes with predicted deleterious nonsynonymous, stop, or splice variants that segregated with severe COPD in at least two pedigrees. Four genes (DNAH8, ALCAM, RARS, and GBF1) also demonstrated an increase in rare nonsynonymous, stop, and/or splice mutations in cases compared with resistant smokers from the COPDGene study; however, these results were not statistically significant. We demonstrate the limitations of the power of this approach under genetic heterogeneity through simulation. CONCLUSIONS Rare deleterious coding variants may increase risk for COPD, but multiple genes likely contribute to COPD susceptibility.
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Affiliation(s)
| | - Christoph Lange
- 2 Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts
| | - Terri H Beaty
- 3 Johns Hopkins Bloomberg School of Public Health, and
| | | | - Kathleen C Barnes
- 5 Division of Allergy and Clinical Immunology, Department of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Michael Bamshad
- 6 Division of Genetic Medicine, Department of Pediatrics, University of Washington and Seattle Children's Hospital, Seattle, Washington
| | - Craig P Hersh
- 1 Channing Division of Network Medicine.,7 Division of Pulmonary and Critical Care Medicine, and
| | | | - Victor M Pinto-Plata
- 8 Department of Critical Care Medicine and Pulmonary Disease, Baystate Medical Center, Springfield, Massachusetts
| | | | - Raphael Bueno
- 10 Division of Thoracic Surgery, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
| | | | - Gerald J Criner
- 11 Division of Pulmonary and Critical Care Medicine Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Edwin K Silverman
- 1 Channing Division of Network Medicine.,7 Division of Pulmonary and Critical Care Medicine, and
| | - Michael H Cho
- 1 Channing Division of Network Medicine.,7 Division of Pulmonary and Critical Care Medicine, and
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30
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Busby T, Meissner JM, Styers ML, Bhatt J, Kaushik A, Hjelmeland AB, Sztul E. The Arf activator GBF1 localizes to plasma membrane sites involved in cell adhesion and motility. CELLULAR LOGISTICS 2017; 7:e1308900. [PMID: 28702273 DOI: 10.1080/21592799.2017.1308900] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 02/20/2017] [Accepted: 03/14/2017] [Indexed: 10/24/2022]
Affiliation(s)
- Theodore Busby
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Justyna M Meissner
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Melanie L Styers
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jay Bhatt
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Akhil Kaushik
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Anita B Hjelmeland
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Elizabeth Sztul
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
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31
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Endocytosis of Wingless via a dynamin-independent pathway is necessary for signaling in Drosophila wing discs. Proc Natl Acad Sci U S A 2016; 113:E6993-E7002. [PMID: 27791132 DOI: 10.1073/pnas.1610565113] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Endocytosis of ligand-receptor complexes regulates signal transduction during development. In particular, clathrin and dynamin-dependent endocytosis has been well studied in the context of patterning of the Drosophila wing disc, wherein apically secreted Wingless (Wg) encounters its receptor, DFrizzled2 (DFz2), resulting in a distinctive dorso-ventral pattern of signaling outputs. Here, we directly track the endocytosis of Wg and DFz2 in the wing disc and demonstrate that Wg is endocytosed from the apical surface devoid of DFz2 via a dynamin-independent CLIC/GEEC pathway, regulated by Arf1, Garz, and class I PI3K. Subsequently, Wg containing CLIC/GEEC endosomes fuse with DFz2-containing vesicles derived from the clathrin and dynamin-dependent endocytic pathway, which results in a low pH-dependent transfer of Wg to DFz2 within the merged and acidified endosome to initiate Wg signaling. The employment of two distinct endocytic pathways exemplifies a mechanism wherein cells in tissues leverage multiple endocytic pathways to spatially regulate signaling.
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32
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Regulators and Effectors of Arf GTPases in Neutrophils. J Immunol Res 2015; 2015:235170. [PMID: 26609537 PMCID: PMC4644846 DOI: 10.1155/2015/235170] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 09/30/2015] [Indexed: 12/22/2022] Open
Abstract
Polymorphonuclear neutrophils (PMNs) are key innate immune cells that represent the first line of defence against infection. They are the first leukocytes to migrate from the blood to injured or infected sites. This process involves molecular mechanisms that coordinate cell polarization, delivery of receptors, and activation of integrins at the leading edge of migrating PMNs. These phagocytes actively engulf microorganisms or form neutrophil extracellular traps (NETs) to trap and kill pathogens with bactericidal compounds. Association of the NADPH oxidase complex at the phagosomal membrane for production of reactive oxygen species (ROS) and delivery of proteolytic enzymes into the phagosome initiate pathogen killing and removal. G protein-dependent signalling pathways tightly control PMN functions. In this review, we will focus on the small monomeric GTPases of the Arf family and their guanine exchange factors (GEFs) and GTPase activating proteins (GAPs) as components of signalling cascades regulating PMN responses. GEFs and GAPs are multidomain proteins that control cellular events in time and space through interaction with other proteins and lipids inside the cells. The number of Arf GAPs identified in PMNs is expanding, and dissecting their functions will provide important insights into the role of these proteins in PMN physiology.
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33
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Zhou F, Dong C, Davis JE, Wu WH, Surrao K, Wu G. The mechanism and function of mitogen-activated protein kinase activation by ARF1. Cell Signal 2015; 27:2035-2044. [PMID: 26169956 DOI: 10.1016/j.cellsig.2015.06.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 06/24/2015] [Indexed: 01/25/2023]
Abstract
Mitogen-activated protein kinases (MAPK) can be activated by a number of biochemical pathways through distinct signaling molecules. We have recently revealed a novel function for the Ras-like small GTPase ADP-ribosylation factor 1 (ARF1) in mediating the activation of Raf1-MEK-ERK1/2 pathway by G protein-coupled receptors [Dong C, Li C and Wu G (2011) J Biol Chem 286, 43,361-43,369]. Here, we have further defined the underlying mechanism and the possible function of ARF1-mediated MAPK pathway. We demonstrated that the blockage of ARF1 activation and the disruption of ARF1 localization to the Golgi by mutating Thr48, a highly conserved residue involved in the exchange of GDP for GTP, and the myristoylation site Gly2 abolished ARF1's ability to activate ERK1/2. In addition, treatment with Golgi structure disrupting agents markedly attenuated ARF1-mediated ERK1/2 activation. Furthermore, ARF1 significantly promoted cell proliferation. More interestingly, ARF1 activated 90kDa ribosomal S6 kinase 1 (RSK1) without influencing Elk-1 activation and ERK2 translocation to the nuclei. These data demonstrate that, once activated, ARF1 activates the MAPK pathway likely using the Golgi as a main platform, which in turn activates the cytoplasmic RSK1, leading to cell proliferation.
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Affiliation(s)
- Fuguo Zhou
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, 1901 Perdido St, New Orleans, LA 70112, United States
| | - Chunmin Dong
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, 1901 Perdido St, New Orleans, LA 70112, United States
| | - Jason E Davis
- Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, 1459 Laney Walker Blvd., Augusta, GA 30912, United States
| | - William H Wu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, 1459 Laney Walker Blvd., Augusta, GA 30912, United States
| | - Kristen Surrao
- Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, 1459 Laney Walker Blvd., Augusta, GA 30912, United States
| | - Guangyu Wu
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, 1901 Perdido St, New Orleans, LA 70112, United States.,Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Regents University, 1459 Laney Walker Blvd., Augusta, GA 30912, United States
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34
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Greninger AL. Picornavirus–Host Interactions to Construct Viral Secretory Membranes. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 129:189-212. [DOI: 10.1016/bs.pmbts.2014.10.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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35
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PI3K signalling in inflammation. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1851:882-97. [PMID: 25514767 DOI: 10.1016/j.bbalip.2014.12.006] [Citation(s) in RCA: 340] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/24/2014] [Accepted: 12/09/2014] [Indexed: 12/13/2022]
Abstract
PI3Ks regulate several key events in the inflammatory response to damage and infection. There are four Class I PI3K isoforms (PI3Kα,β,γ,δ), three Class II PI3K isoforms (PI3KC2α, C2β, C2γ) and a single Class III PI3K. The four Class I isoforms synthesise the phospholipid 'PIP3'. PIP3 is a 'second messenger' used by many different cell surface receptors to control cell movement, growth, survival and differentiation. These four isoforms have overlapping functions but each is adapted to receive efficient stimulation by particular receptor sub-types. PI3Kγ is highly expressed in leukocytes and plays a particularly important role in chemokine-mediated recruitment and activation of innate immune cells at sites of inflammation. PI3Kδ is also highly expressed in leukocytes and plays a key role in antigen receptor and cytokine-mediated B and T cell development, differentiation and function. Class III PI3K synthesises the phospholipid PI3P, which regulates endosome-lysosome trafficking and the induction of autophagy, pathways involved in pathogen killing, antigen processing and immune cell survival. Much less is known about the function of Class II PI3Ks, but emerging evidence indicates they can synthesise PI3P and PI34P2 and are involved in the regulation of endocytosis. The creation of genetically-modified mice with altered PI3K signalling, together with the development of isoform-selective, small-molecule PI3K inhibitors, has allowed the evaluation of the individual roles of Class I PI3K isoforms in several mouse models of chronic inflammation. Selective inhibition of PI3Kδ, γ or β has each been shown to reduce the severity of inflammation in one or more models of autoimmune disease, respiratory disease or allergic inflammation, with dual γ/δ or β/δ inhibition generally proving more effective. The inhibition of Class I PI3Ks may therefore offer a therapeutic opportunity to treat non-resolving inflammatory pathologies in humans. This article is part of a Special Issue entitled Phosphoinositides.
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36
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Arst HN, Hernandez-Gonzalez M, Peñalva MA, Pantazopoulou A. GBF/Gea mutant with a single substitution sustains fungal growth in the absence of BIG/Sec7. FEBS Lett 2014; 588:4799-806. [PMID: 25451223 PMCID: PMC4266534 DOI: 10.1016/j.febslet.2014.11.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 11/07/2014] [Accepted: 11/10/2014] [Indexed: 12/11/2022]
Abstract
A. nidulans has a GBF/Gea and a BIG/Sec7 subfamily Golgi Arf1-GEFs, both essential. The late Golgi Arf1-GEF mutant hypB5 conditionally blocks secretion. Residue substitution in the early Golgi Arf1-GEF GeaA suppresses hypB5 and hypBΔ. The mutation alters a GBF/Gea amino acid motif and shifts GeaA localization. GeaA1 alone satisfies the eukaryotic requirement for two Golgi Arf1 GEFs.
Golgi Arf1-guanine nucleotide exchange factors (GEFs) belong to two subfamilies: GBF/Gea and BIG/Sec7. Both are conserved across eukaryotes, but the physiological role of each is not well understood. Aspergillus nidulans has a single member of the early Golgi GBF/Gea-subfamily, geaA, and the late Golgi BIG/Sec7-subfamily, hypB. Both geaA and hypB are essential. hypB5 conditionally blocks secretion. We sought extragenic hypB5 suppressors and obtained geaA1. geaA1 results in Tyr1022Cys within a conserved GBF/Gea-specific S(Y/W/F)(L/I) motif in GeaA. This mutation alters GeaA localization. Remarkably, geaA1 suppresses hypBΔ, indicating that a single mutant Golgi Arf1-GEF suffices for growth.
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Affiliation(s)
- Herbert N Arst
- Section of Microbiology, Department of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; Centro de Investigaciones Biológicas, CSIC, Madrid 28040, Spain
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Schultz ML, Tecedor L, Stein CS, Stamnes MA, Davidson BL. CLN3 deficient cells display defects in the ARF1-Cdc42 pathway and actin-dependent events. PLoS One 2014; 9:e96647. [PMID: 24792215 PMCID: PMC4008583 DOI: 10.1371/journal.pone.0096647] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 04/09/2014] [Indexed: 01/08/2023] Open
Abstract
Juvenile Batten disease (juvenile neuronal ceroid lipofuscinosis, JNCL) is a devastating neurodegenerative disease caused by mutations in CLN3, a protein of undefined function. Cell lines derived from patients or mice with CLN3 deficiency have impairments in actin-regulated processes such as endocytosis, autophagy, vesicular trafficking, and cell migration. Here we demonstrate the small GTPase Cdc42 is misregulated in the absence of CLN3, and thus may be a common link to multiple cellular defects. We discover that active Cdc42 (Cdc42-GTP) is elevated in endothelial cells from CLN3 deficient mouse brain, and correlates with enhanced PAK-1 phosphorylation, LIMK membrane recruitment, and altered actin-driven events. We also demonstrate dramatically reduced plasma membrane recruitment of the Cdc42 GTPase activating protein, ARHGAP21. In line with this, GTP-loaded ARF1, an effector of ARHGAP21 recruitment, is depressed. Together these data implicate misregulated ARF1-Cdc42 signaling as a central defect in JNCL cells, which in-turn impairs various cell functions. Furthermore our findings support concerted action of ARF1, ARHGAP21, and Cdc42 to regulate fluid phase endocytosis in mammalian cells. The ARF1-Cdc42 pathway presents a promising new avenue for JNCL therapeutic development.
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Affiliation(s)
- Mark L. Schultz
- Program of Molecular and Cellular Biology, University of Iowa, Iowa City, Iowa, United States of America
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Luis Tecedor
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Colleen S. Stein
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Mark A. Stamnes
- Department of Molecular Physiology and Biophysics, Iowa City, Iowa, United States of America
| | - Beverly L. Davidson
- Program of Molecular and Cellular Biology, University of Iowa, Iowa City, Iowa, United States of America
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States of America
- Department of Molecular Physiology and Biophysics, Iowa City, Iowa, United States of America
- Department of Neurology, Iowa City, Iowa, United States of America
- * E-mail:
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Regulating the large Sec7 ARF guanine nucleotide exchange factors: the when, where and how of activation. Cell Mol Life Sci 2014; 71:3419-38. [PMID: 24728583 DOI: 10.1007/s00018-014-1602-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 02/27/2014] [Accepted: 03/03/2014] [Indexed: 10/25/2022]
Abstract
Eukaryotic cells require selective sorting and transport of cargo between intracellular compartments. This is accomplished at least in part by vesicles that bud from a donor compartment, sequestering a subset of resident protein "cargos" destined for transport to an acceptor compartment. A key step in vesicle formation and targeting is the recruitment of specific proteins that form a coat on the outside of the vesicle in a process requiring the activation of regulatory GTPases of the ARF family. Like all such GTPases, ARFs cycle between inactive, GDP-bound, and membrane-associated active, GTP-bound, conformations. And like most regulatory GTPases the activating step is slow and thought to be rate limiting in cells, requiring the use of ARF guanine nucleotide exchange factor (GEFs). ARF GEFs are characterized by the presence of a conserved, catalytic Sec7 domain, though they also contain motifs or additional domains that confer specificity to localization and regulation of activity. These domains have been used to define and classify five different sub-families of ARF GEFs. One of these, the BIG/GBF1 family, includes three proteins that are each key regulators of the secretory pathway. GEF activity initiates the coating of nascent vesicles via the localized generation of activated ARFs and thus these GEFs are the upstream regulators that define the site and timing of vesicle production. Paradoxically, while we have detailed molecular knowledge of how GEFs activate ARFs, we know very little about how GEFs are recruited and/or activated at the right time and place to initiate transport. This review summarizes the current knowledge of GEF regulation and explores the still uncertain mechanisms that position GEFs at "budding ready" membrane sites to generate highly localized activated ARFs.
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Gambardella L, Vermeren S. Molecular players in neutrophil chemotaxis-focus on PI3K and small GTPases. J Leukoc Biol 2013; 94:603-12. [DOI: 10.1189/jlb.1112564] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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Bouvet S, Golinelli-Cohen MP, Contremoulins V, Jackson CL. Targeting of the Arf-GEF GBF1 to lipid droplets and Golgi membranes. J Cell Sci 2013; 126:4794-805. [DOI: 10.1242/jcs.134254] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Lipid droplet metabolism and secretory pathway trafficking both require activation of the Arf1 small G protein. The spatio-temporal regulation of Arf1 activation is mediated by guanine nucleotide exchange factors (GEFs) of the GBF and BIG families, but the mechanisms of their localization to multiple sites within cells are poorly understood. Here we show that GBF1 has a lipid-binding domain (HDS1) immediately downstream of the catalytic Sec7 domain, which mediates association with both lipid droplets and Golgi membranes in cells, and with bilayer liposomes and artificial droplets in vitro. An amphipathic helix within HDS1 is necessary and sufficient for lipid binding, both in vitro and in cells. The HDS1 domain of GBF1 is stably associated with lipid droplets in cells, and the catalytic Sec7 domain inhibits this potent lipid droplet binding capacity. Additional sequences upstream of the Sec7 domain-HDS1 tandem are required for localization to Golgi membranes. This mechanism provides insight into crosstalk between lipid droplet function and secretory trafficking.
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