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Sravani Banerjee, David Aponte-Diaz, Calvin Yeager, Suresh D Sharma, Gang Ning, Hyung S Oh, Qingxia Han, Masato Umeda, Yuji Hara, Robert Y L Wang, Craig E Cameron
RNA viruses induce specialized membranous structures for use in genome replication. These structures are often referred to as replication organelles (ROs). ROs exhibit distinct lipid composition relative to other cellular membranes. In many picornaviruses, phosphatidylinositol-4-phosphate (PI4P) is a marker of the RO. Studies to date indicate that the viral 3A protein hijacks a PI4 kinase to induce PI4P by a mechanism unrelated to the cellular pathway, which requires Golgi-specific brefeldin A-resistance guanine nucleotide exchange factor 1, GBF1, and ADP ribosylation factor 1, Arf1...
May 21, 2018: PLoS Pathogens
Dana A Davis
Endoplasmic reticulum (ER)-mitochondria tethering by the ERMES complex is critical for numerous mitochondrial functions in fungi. It was recently discovered that the GTPase Arf1, which regulates within Golgi vesicular trafficking also affects ER-mitochondrial tethering potentially through ERMES. In Candida albicans, Arf1 not only functions in vesicular trafficking and affects ERMES but also impacts reactive oxygen species generation, which is a key immune defense molecule.
May 15, 2018: FEBS Journal
Mugdha Sathe, Gayatri Muthukrishnan, James Rae, Andrea Disanza, Mukund Thattai, Giorgio Scita, Robert G Parton, Satyajit Mayor
Using real-time TIRF microscopy imaging, we identify sites of clathrin and dynamin-independent CLIC/GEEC (CG) endocytic vesicle formation. This allows spatio-temporal localisation of known molecules affecting CG endocytosis; GBF1 (a GEF for ARF1), ARF1 and CDC42 which appear sequentially over 60 s, preceding scission. In an RNAi screen for BAR domain proteins affecting CG endocytosis, IRSp53 and PICK1, known interactors of CDC42 and ARF1, respectively, were selected. Removal of IRSp53, a negative curvature sensing protein, abolishes CG endocytosis...
May 9, 2018: Nature Communications
Yuki Miyamoto, Tomohiro Torii, Kenji Tago, Akito Tanoue, Shou Takashima, Junji Yamauchi
During development of the peripheral nervous system in mammals, Schwann cells wrap their plasma membranes around neuronal axons, forming multiple myelin sheaths. A mature myelin sheath insulates axons and increases nerve conduction velocity while protecting nerve fibers from various stresses such as physical ones. Despite this functional importance, the molecular units that underlie dynamic morphological changes in formation of myelin sheaths are not sufficiently understood. Arf1 is a small guanosine triphosphate-binding protein that plays multiple roles in intracellular trafficking and related signaling, both of which are processes involved in cell morphogenesis...
April 2018: Science Advances
Eriko Kage-Nakadai, Simo Sun, Satoru Iwata, Sawako Yoshina, Yoshikazu Nishikawa, Shohei Mitani
The membrane trafficking events that regulate unicellular tube formation and maintenance are not well understood. Here, using an RNAi screen, we identified the small GTPase ARF1 homolog ARF-1.2 as a regulator of excretory tube formation in Caenorhabditis elegans. RNAi-mediated knockdown and knockout of the arf-1.2 gene resulted in the formation of large intracellular vacuoles at the growth sites (varicosities) of the excretory canals. arf-1.2 mutant animals were sensitive to hyperosmotic conditions. arf-1.2 RNAi affected the localization of the anion transporter SULP-8, which is expressed in the basal plasma membrane of the excretory canals, but did not affect the expression of SULP-4, which is expressed in the apical membrane...
April 27, 2018: Journal of Physiological Sciences: JPS
Rajeth Koneru, Heather Bimonte-Nelson, Vincent Ciavatta, Woldeab Haile, Kate Elmore, Jennifer Ward, Leonard Maroun, William R Tyor
OBJECTIVE: Increased brain interferon-alpha (IFNα) is associated with neurodegenerative disorders, including HIV-associated neurocognitive disorders (HAND). HAND occurs in approximately 50% of individuals with HIV despite combined antiretroviral therapy (cART). Therefore, adjunctive therapies must be developed that prevent progression of mild forms of HAND to HIV-associated dementia. Increased IFNα in the CNS has been associated with HAND in patients and in a HAND mouse model. DESIGN AND METHODS: B18R binds IFNα and ameliorates HAND mouse brain histopathology (HIV encephalitis)...
April 19, 2018: AIDS
Hee-Seung Choi, Minji Seo, Hyung-Taeg Cho
Auxin signaling is finalized by activator auxin response factors (aARFs) that are released from Auxin/Indole-3-Acetic Acid (Aux/IAA) repressors and directly activate auxin-responsive genes. However, it remains to be answered how repressor ARFs (rARFs) exert their repression function. In this study, we assessed the molecular and biological functions of two putative co-repressor-binding motifs (EAR and RLFGI) of ARF2 (a rARF) in Arabidopsis thaliana . In the yeast two-hybrid assay, the EAR mutation moderately and the RLFGI mutation, or both motifs, almost completely disrupted the interaction between the co-repressor TOPLESS (TPL) and the repressive motifs-containing middle domain (MD) of ARF2...
2018: Frontiers in Plant Science
Charlotte Luchsinger, Marcelo Aguilar, Patricia V Burgos, Pamela Ehrenfeld, Gonzalo A Mardones
Increasing evidence indicates that the Golgi apparatus plays active roles in cancer, but a comprehensive understanding of its functions in the oncogenic transformation has not yet emerged. At the same time, the Golgi is becoming well recognized as a hub that integrates its functions of protein and lipid biosynthesis to signal transduction for cell proliferation and migration in cancer cells. Nevertheless, the active function of the Golgi apparatus in cancer cells has not been fully evaluated as a target for combined treatment...
2018: PloS One
Bing Zhang, Qilin Yu, Da Huo, Jianrong Li, Chao Liang, Hongyue Li, Xiao Yi, Chenpeng Xiao, Dan Zhang, Mingchun Li
The Arf family of small GTP-binding and hydrolyzing proteins is one of the most important intracellular regulators of membrane dynamics. In this study, we identified the Golgi-localized Arf family G protein Arf1 in Candida albicans and confirmed its conserved function in regulating the secretory pathway. Interestingly, deletion of ARF1 resulted in intracellular oxygen reactive species (ROS) accumulation, and induced formation of the endoplasmic reticulum (ER)-mitochondria encounter structure (ERMES). Moreover, N-acetylcysteine (NAC)-mediated ROS scavenging in the arf1Δ/Δ strain attenuated ERMES formation, indicating that intracellular ROS accumulation resulting from ARF1 deletion facilitated ERMES formation...
March 30, 2018: FEBS Journal
Steve L Halaby, J Christopher Fromme
The Golgi complex is the central membrane and protein-sorting station in eukaryotic cells. Activation of Arf (ADP-ribosylation factor) 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 homology upstream of Sec7 (HUS) box, with an unknown mechanistic role...
May 4, 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...
June 2018: Cellular Signalling
Catherine E Gilbert, Elizabeth Sztul, Carolyn E Machamer
Cold temperature blocks used to synchronize protein trafficking inhibit GBF1 function, leading to a decrease in ARF1-GTP levels and mislocalization of the ARF1 effector golgin-160. Several other, but not all, Golgi proteins including ARL1 also mislocalize. ARF1 activity and golgin-160 localization require more than 30 min to recover from these blocks.
April 15, 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 a senescence-associated secretory phenotype (SASP). The factors secreted by cells with a SASP have multiple biological functions that are mediated in an autocrine or paracrine manner. However, the status of the protein kinase D1 (PKD1; also known as PRKD1)-mediated classical protein secretory pathway, from the trans-Golgi network (TGN) to the cell surface, during cellular senescence and its role in the cellular senescence response remain unknown. Here, we show that the activities or quantities of critical components of this pathway, including PKD1, ADP-ribosylation factor 1 (ARF1) and phosphatidylinositol 4-kinase IIIβ (PI4KIIIβ), at the TGN are increased in senescent cells...
March 16, 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 (M3 R)...
January 2018: 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
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