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Steve L Halaby, J Christopher Fromme
The Golgi complex is the central membrane and protein sorting station in eukaryotic cells. Activation of ADP ribosylation factor (Arf) GTPases is essential for vesicle formation via recruitment of cargo adaptors and coat proteins necessary for Golgi trafficking. Arf activation is spatially and temporally regulated by distinct guanine nucleotide exchange factors (GEFs) at different Golgi compartments. The yeast Arf-GEF Sec7 is a conserved and essential activator of Arf1 at the trans-Golgi network. Sec7 contains a highly conserved regulatory region, the HUSbox, with an unknown mechanistic role...
March 7, 2018: Journal of Biological Chemistry
Ricardo Charles, Mohamed Bourmoum, Audrey Claing
Vascular smooth muscle cells (VSMC) can exhibit a contractile or a synthetic phenotype depending on the extracellular stimuli present and the composition of the extracellular matrix. Uncontrolled activation of the synthetic VSMC phenotype is however associated with the development of cardiovascular diseases. Here, we aimed to elucidate the role of the ARF GTPases in the regulation of VSMC dedifferentiation. First, we observed that the inhibition of the activation of ARF proteins with SecinH3, a blocker of the cytohesin ARF GEF family, reduced the ability of the cells to migrate and proliferate...
February 27, 2018: Cellular Signalling
Catherine E Gilbert, Elizabeth Sztul, Carolyn E Machamer
ADP-ribosylation factor (ARF) proteins are key regulators of the secretory pathway. ARF1, through interacting with its effectors, regulates protein trafficking by facilitating numerous events at the Golgi. One unique ARF1 effector is golgin-160, which promotes the trafficking of only a specific subset of cargo proteins through the Golgi. While studying this role of golgin-160, we discovered that commonly used cold temperature blocks utilized to synchronize cargo trafficking (20°C and 16°C) caused golgin-160 dispersal from Golgi membranes...
February 21, 2018: Molecular Biology of the Cell
Sujit Kashyap, Uma Kumar, Anuj Kumar Pandey, Maumita Kanjilal, Patralika Chattopadhyay, Chandrashekhar Yadav, B K Thelma
OBJECTIVES: ARL15 is a novel susceptibility gene identified in a recent GWAS in a north Indian rheumatoid arthritis (RA) cohort. However, the role of ARL15 or ARF family genes in RA aetiology remains unknown. Therefore, we aimed to i) establish the expression of ARL15 in rheumatoid arthritis synovial fibroblasts (RASF) and ii) its functional characterisation by assessing its effects on major inflammatory cytokines and interacting partners using a knockdown approach. METHODS: RASF were cultured from synovial tissue obtained from RA patients (n=5) and osteoarthritis (OA) patients (n=3) serving as controls...
February 14, 2018: Clinical and Experimental Rheumatology
Alfredo Toledo-Leyva, Julio César Villegas-Pineda, Sergio Encarnación-Guevara, Dolores Gallardo-Rincón, Patricia Talamás-Rohana
Background: Epithelial ovarian cancer is the second most lethal gynecological cancer worldwide. Ascites can be found in all clinical stages, however in advanced disease stages IIIC and IV it is more frequent and could be massive, associated with worse prognosis. Due to the above, it was our interest to understanding how the ascites of ovarian cancer patients induces the mechanisms by which the cells present in it acquire a more aggressive phenotype and to know new proteins associated to this process...
2018: Proteome Science
Eun-Hye Hong, Ji-Ye Kim, Jeong-Hoon Kim, Dae-Sik Lim, Minkyu Kim, Jeong-Yoon Kim
Proper dendrite development is essential for establishing neural circuitry, and Rho GTPases play key regulatory roles in this process. From mouse brain lysates, we identified Brefeldin A-inhibited guanine exchange factor 2 (BIG2) as a novel Rho GTPase regulatory protein involved in dendrite growth and maintenance. BIG2 was highly expressed during early development, and knockdown of the ARFGEF2 gene encoding BIG2 significantly reduced total dendrite length and the number of branches. Expression of the constitutively active ADP-ribosylation factor 1 ARF1 Q71L rescued the defective dendrite morphogenesis of ARFGEF2-null neurons, indicating that BIG2 controls dendrite growth and maintenance by activating ARF1...
February 17, 2018: Molecular Neurobiology
Yuanyuan Su, Pengfeng Wang, Hong Shen, Zhaomeng Sun, Chenzhong Xu, Guodong Li, Tanjun Tong, Jun Chen
Senescent cells develop senescence-associated secretory phenotype (SASP) which possesses multiple biological functions via autocrine or paracrine manner. However, the status of the protein kinase D1 (PKD1)-mediated classical protein secretory pathway from trans-Golgi network (TGN) to cell surface during cellular senescence and its role in cellular senescent response remain unknown. Here, we show that the activities or quantities of the critical components of this pathway including PKD1, ADP-ribosylation factor 1 (ARF1), and phosphatidylinositol 4-kinase IIIβ (PI4KIIIβ) at TGN are increased in senescent cells...
February 2, 2018: Journal of Cell Science
Christopher M Ziegler, Philip Eisenhauer, Jamie A Kelly, Loan N Dang, Vedran Beganovic, Emily A Bruce, Benjamin R King, David J Shirley, Marion E Weir, Bryan A Ballif, Jason Botten
Arenaviruses are negative-strand, enveloped RNA viruses that cause significant human disease. In particular, Junín mammarenvirus (JUNV) is the etiologic agent of Argentine hemorrhagic fever. At present, little is known about the cellular proteins that the arenavirus matrix protein (Z) hijacks to accomplish its various functions, including driving the process of virus release. Further, there is a little knowledge regarding host proteins incorporated into arenavirus particles and their importance for virion function...
November 29, 2017: Journal of Virology
Priyanka Rai, Mukesh Kumar, Geetika Sharma, Pradeep Barak, Saumitra Das, Siddhesh S Kamat, Roop Mallik
Despite massive fluctuations in its internal triglyceride content, the liver secretes triglyceride under tight homeostatic control. This buffering function is most visible after fasting, when liver triglyceride increases manyfold but circulating serum triglyceride barely fluctuates. How the liver controls triglyceride secretion is unknown, but is fundamentally important for lipid and energy homeostasis in animals. Here we find an unexpected cellular and molecular mechanism behind such control. We show that kinesin motors are recruited to triglyceride-rich lipid droplets (LDs) in the liver by the GTPase ARF1, which is a key activator of lipolysis...
December 5, 2017: Proceedings of the National Academy of Sciences of the United States of America
Ok-Ryul Song, Christophe J Queval, Raffaella Iantomasi, Vincent Delorme, Sabrina Marion, Romain Veyron-Churlet, Elisabeth Werkmeister, Michka Popoff, Isabelle Ricard, Samuel Jouny, Nathalie Deboosere, Frank Lafont, Alain Baulard, Edouard Yeramian, Laurent Marsollier, Eik Hoffmann, Priscille Brodin
The interaction of Mycobacterium tuberculosis (Mtb) with pulmonary epithelial cells is critical for early stages of bacillus colonization and during the progression of tuberculosis. Entry of Mtb into epithelial cells has been shown to depend on F-actin polymerization, though the molecular mechanisms are still unclear. Here, we demonstrate that mycobacterial uptake into epithelial cells requires rearrangements of the actin cytoskeleton, which are regulated by ADP-ribosylation factor 1 (Arf1) and phospholipase D1 (PLD1), and is dependent on the M3 muscarinic receptor (M3R)...
November 15, 2017: EMBO Reports
Beata Kaczmarek, Jean-Marc Verbavatz, Catherine L Jackson
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...
December 2017: Biology of the Cell
Yuichi Mazaki, Yasuhito Onodera, Tsunehito Higashi, Takahiro Horinouchi, Tsukasa Oikawa, Hisataka Sabe
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...
October 2, 2017: Cell Communication and Signaling: CCS
Na Zhang, Leiliang Zhang
The infection of CHIKV is associated with cellular membranes; however whether early secretory pathways are involved in CHIKV replication remains unclear. In the present study, we have provided initial evidences that CHIKV requires both COPI and COPII for its replication. Small interfering RNAs against COPI components, including coatomer, ARFs or GBF1, suppress CHIKV replication. Moreover, CHIKV infection is abolished by the presence of ARF1 inhibitor brefeldin A or GBF1 inhibitor golgicide A. In addition, perturbation of COPII by silencing key components of COPII pathways leads to a reduction in CHIKV replication...
November 25, 2017: Biochemical and Biophysical Research Communications
Tu'uhevaha J Kaitu'u-Lino, Fiona C Brownfoot, Roxanne Hastie, Ashwini Chand, Ping Cannon, Minh Deo, Laura Tuohey, Clare Whitehead, Natalie J Hannan, Stephen Tong
Preeclampsia is a major pregnancy complication associated with poor placental perfusion and placental hypoxia. Systemic and placental inflammation and elevated placental secretion of the antiangiogenic factors sFlt-1 (soluble fms-like tyrosine kinase 1) and sEng (soluble endoglin) are hallmarks of preeclampsia, causing endothelial dysfunction and multiorgan injury. A molecule that links placental hypoxia, inflammation, and antiangiogenic factor release has not been described. ATF3 (activating transcription factor 3) is highly expressed in placenta...
November 2017: Hypertension
Xue-Hai Liang, Hong Sun, Wen Shen, Shiyu Wang, Joyee Yao, Michael T Migawa, Huynh-Hoa Bui, Sagar S Damle, Stan Riney, Mark J Graham, Rosanne M Crooke, Stanley T Crooke
A variety of diseases are caused by deficiencies in amounts or activity of key proteins. An approach that increases the amount of a specific protein might be of therapeutic benefit. We reasoned that translation could be specifically enhanced using trans-acting agents that counter the function of negative regulatory elements present in the 5' UTRs of some mRNAs. We recently showed that translation can be enhanced by antisense oligonucleotides (ASOs) that target upstream open reading frames. Here we report the amount of a protein can also be selectively increased using ASOs designed to hybridize to other translation inhibitory elements in 5' UTRs...
September 19, 2017: Nucleic Acids Research
Deepti Karandur, Agata Nawrotek, John Kuriyan, Jacqueline Cherfils
Lipidated small GTPases and their regulators need to bind to membranes to propagate actions in the cell, but an integrated understanding of how the lipid bilayer exerts its effect has remained elusive. Here we focused on ADP ribosylation factor (Arf) GTPases, which orchestrate a variety of regulatory functions in lipid and membrane trafficking, and their activation by the guanine-nucleotide exchange factor (GEF) Brag2, which controls integrin endocytosis and cell adhesion and is impaired in cancer and developmental diseases...
October 24, 2017: Proceedings of the National Academy of Sciences of the United States of America
Jinya Guo, Yansong Miao, Yi Cai
Topology of membrane proteins provides important information for the understanding of protein function and intermolecular associations. Integrate membrane proteins are generally transported from endoplasmic reticulum (ER) to Golgi and downstream compartments in the plant secretory pathway. Here, we describe a simple method to study membrane protein topology along the plant secretory pathway by transiently coexpressing a fluorescent protein (XFP)-tagged membrane protein and an ER export inhibitor protein, ARF1 (T31N), in tobacco BY-2 protoplast...
2017: Methods in Molecular Biology
Sarah Benabdi, François Peurois, Agata Nawrotek, Jahnavi Chikireddy, Tatiana Cañeque, Takao Yamori, Isamu Shiina, Yoshimi Ohashi, Shingo Dan, Raphaël Rodriguez, Jacqueline Cherfils, Mahel Zeghouf
Arf GTPases and their guanine nucleotide exchange factors (ArfGEFs) are major regulators of membrane traffic and organelle structure in cells. They are associated with a variety of diseases and are thus attractive therapeutic targets for inhibition by small molecules. Several inhibitors of unrelated chemical structures have been discovered, which have shown their potential in dissecting molecular pathways and blocking disease-related functions. However, their specificity across the ArfGEF family has remained elusive...
September 26, 2017: Biochemistry
Liwei Lang, Chloe Shay, Xiangdong Zhao, Yong Teng
BACKGROUND: Although major improvements have been made in surgical management, chemotherapeutic, and radiotherapeutic of prostate cancer, many prostate cancers remain refractory to treatment with standard agents. Therefore, the identification of new molecular targets in cancer progression and development of novel therapeutic strategies to target them are very necessary for achieving better survival for patients with prostate cancer. Activation of small GTPases such as Ras and Arf1 is a critical component of the signaling pathways for most of the receptors shown to be upregulated in advanced prostate cancer...
August 23, 2017: Journal of Experimental & Clinical Cancer Research: CR
Etienne Sauvageau, Peter J McCormick, Stephane Lefrancois
AP-1 is a clathrin adaptor recruited to the trans-Golgi Network where it can interact with specific signals found in the cytosolic tail of cargo proteins to incorporate them into clathrin-coated vesicles for trafficking. The small G protein Arf1 regulates the spatiotemporal recruitment of AP-1 and also drives a conformational change favoring an interaction with cargo proteins. A recent crystal structure and in vitro experiments highlighted potential residues mediating the AP-1/Arf1 interaction and the unlocking of the complex...
August 2, 2017: Scientific Reports
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