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https://www.readbyqxmd.com/read/28904211/zonda-is-a-novel-early-component-of-the-autophagy-pathway-in-drosophila
#1
Mariana Melani, Ayelén Valko, Nuria M Romero, Milton O Aguilera, Julieta M Acevedo, Zambarlal Bhujabal, Joel Perez-Perri, Rocío V de la Riva-Carrasco, Maximiliano J Katz, Eleonora Sorianello, Cecilia D'Alessio, Gabor Juhász, Terje Johansen, María I Colombo, Pablo Wappner
Autophagy is an evolutionary conserved process by which eukaryotic cells undergo self-digestion of cytoplasmic components. Here we report that a novel Drosophila immunophilin, which we have named Zonda, is critically required for starvation-induced autophagy. We show that Zonda operates at early stages of the process, specifically for Vps34-mediated phosphatidylinositol 3-phosphate (PI3P) deposition. Zonda displays an even distribution under basal conditions, and soon after starvation nucleates in endoplasmic reticulum-associated foci that colocalize with omegasome markers...
September 13, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28903944/a-dual-role-for-the-class-iii-pi3k-vps34-in-platelet-production-and-thrombus-growth
#2
Colin Valet, Marie Levade, Gaëtan Chicanne, Benoit Bilanges, Cendrine Cabou, Julien Viaud, Marie-Pierre Gratacap, Frédérique Gaits-Iacovoni, Bart Vanhaesebroeck, Bernard Payrastre, Sonia Severin
To uncover the role of Vps34, the sole class III phosphoinositide 3-kinase, in megakaryocytes (MKs) and platelets, we created a mouse model with Vps34 deletion in the MK/platelet lineage (Pf4-Cre/Vps34(lox/lox)). Deletion of Vps34 in MKs led to the loss of its regulator protein Vps15, and was associated with microthrombocytopenia and platelet granule abnormalities. While Vps34 deficiency did not impact on MK polyploidisation or proplatelet formation, it dampened MK granule biogenesis and directional migration towards an SDF1α gradient, leading to ectopic platelet release within the bone marrow...
September 13, 2017: Blood
https://www.readbyqxmd.com/read/28882875/class-iii-pi3k-positively-regulates-platelet-activation-and-thrombosis-via-pi-3-p-directed-function-of-nadph-oxidase
#3
Yangyang Liu, Mengjiao Hu, Dongjiao Luo, Ming Yue, Shuai Wang, Xiaoyan Chen, Yangfan Zhou, Yi Wang, Yanchun Cai, Xiaolan Hu, Yuehai Ke, Zhongzhou Yang, Hu Hu
OBJECTIVE: Class III phosphoinositide 3-kinase, also known as vacuolar protein sorting 34 (VPS34), is a highly conserved enzyme regulating important cellular functions such as NADPH oxidase (NOX) assembly, membrane trafficking, and autophagy. Although VPS34 is expressed in platelets, its involvement in platelet activation remains unclear. Herein, we investigated the role of VPS34 in platelet activation and thrombus formation using VPS34 knockout mice. APPROACH AND RESULTS: Platelet-specific VPS34-deficient mice were generated and characterized...
September 7, 2017: Arteriosclerosis, Thrombosis, and Vascular Biology
https://www.readbyqxmd.com/read/28877469/autophagy-independent-lysosomal-targeting-regulated-by-ulk1-2-fip200-and-atg9
#4
Jonathan M Goodwin, William E Dowdle, Rowena DeJesus, Zuncai Wang, Philip Bergman, Marek Kobylarz, Alicia Lindeman, Ramnik J Xavier, Gregory McAllister, Beat Nyfeler, Gregory Hoffman, Leon O Murphy
Iron is vital for many homeostatic processes, and its liberation from ferritin nanocages occurs in the lysosome. Studies indicate that ferritin and its binding partner nuclear receptor coactivator-4 (NCOA4) are targeted to lysosomes by a form of selective autophagy. By using genome-scale functional screening, we identify an alternative lysosomal transport pathway for ferritin that requires FIP200, ATG9A, VPS34, and TAX1BP1 but lacks involvement of the ATG8 lipidation machinery that constitutes classical macroautophagy...
September 5, 2017: Cell Reports
https://www.readbyqxmd.com/read/28872463/mtorc1-hyperactivation-arrests-bone-growth-in-lysosomal-storage-disorders-by-suppressing-autophagy
#5
Rosa Bartolomeo, Laura Cinque, Chiara De Leonibus, Alison Forrester, Anna Chiara Salzano, Jlenia Monfregola, Emanuela De Gennaro, Edoardo Nusco, Isabella Azario, Carmela Lanzara, Marta Serafini, Beth Levine, Andrea Ballabio, Carmine Settembre
The mammalian target of rapamycin complex 1 (mTORC1) kinase promotes cell growth by activating biosynthetic pathways and suppressing catabolic pathways, particularly that of macroautophagy. A prerequisite for mTORC1 activation is its translocation to the lysosomal surface. Deregulation of mTORC1 has been associated with the pathogenesis of several diseases, but its role in skeletal disorders is largely unknown. Here, we show that enhanced mTORC1 signaling arrests bone growth in lysosomal storage disorders (LSDs)...
September 5, 2017: Journal of Clinical Investigation
https://www.readbyqxmd.com/read/28846113/vps34-stimulation-of-p62-phosphorylation-for-cancer-progression
#6
X Jiang, Y Bao, H Liu, X Kou, Z Zhang, F Sun, Z Qian, Z Lin, X Li, X Liu, L Jiang, Y Yang
Vps34, a class III PtdIns3 lipid kinase involved in the control of both autophagic and endocytic systems, has been studied extensively in numerous fundamental cellular processes. Accumulating evidence indicates that Vps34 may also contribute to the development and progression of human cancers. However, the mechanism of Vps34 in tumorigenesis remains elusive. Here, we report an unanticipated role of Vps34 in the activation of p62 for cancer development. We identified that Vps34 is a transcriptional activator of p62 through competition of Nrf2 (nuclear factor erythroid 2-related factor 2) for Keap1 binding...
August 28, 2017: Oncogene
https://www.readbyqxmd.com/read/28844862/vps34-acetylation-controls-its-lipid-kinase-activity-and-the-initiation-of-canonical-and-non-canonical-autophagy
#7
Hua Su, Fei Yang, Qiuting Wang, Qiuhong Shen, Jingtao Huang, Chao Peng, Yi Zhang, Wei Wan, Catherine C L Wong, Qiming Sun, Fudi Wang, Tianhua Zhou, Wei Liu
The class III phosphoinositide 3-kinase VPS34 plays a key role in the regulation of vesicular trafficking and macroautophagy. So far, we know little about the molecular mechanism of VPS34 activation besides its interaction with regulatory proteins to form complexes. Here, we report that VPS34 is specifically acetylated by the acetyltransferase p300, and p300-mediated acetylation represses VPS34 activity. Acetylation at K771 directly diminishes the affinity of VPS34 for its substrate PI, while acetylation at K29 hinders the VPS34-Beclin 1 core complex formation...
August 23, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28779993/the-class-i-pi3k-inhibitor-s14161-induces-autophagy-in-malignant-blood-cells-by-modulating-the-beclin-1-vps34-complex
#8
Siyu Wang, Jie Li, Yanyun Du, Yujia Xu, Yali Wang, Zubin Zhang, Zhuan Xu, Yuanying Zeng, Xinliang Mao, Biyin Cao
S14161 is a pan-Class I PI3K inhibitor that induces blood cancer cell death, but its mechanism is largely unknown. In the present study, we evaluated the role of S14161 in autophagy, an emerging event in cell destination. Multiple myeloma cell lines RPMI-8226, OPM2, KMS11 and leukemia cell line K562 were treated with S14161. The results showed that S14161 induced autophagy as demonstrated by increased LC3-II and decreased p62, which were prevented by autophagy inhibitors including 3-methyladenine and bafilomycin A1...
August 2017: Journal of Pharmacological Sciences
https://www.readbyqxmd.com/read/28757208/vps34-kinase-domain-dynamics-regulate-the-autophagic-pi-3-kinase-complex
#9
Goran Stjepanovic, Sulochanadevi Baskaran, Mary G Lin, James H Hurley
The class III phosphatidylinositol 3-kinase complex I (PI3KC3-C1) is required for the initiation of essentially all macroautophagic processes. PI3KC3-C1 consists of the lipid kinase catalytic subunit VPS34, the VPS15 scaffold, and the regulatory BECN1 and ATG14 subunits. The VPS34 catalytic domain and BECN1:ATG14 subcomplex do not touch, and it is unclear how allosteric signals are transmitted to VPS34. We used EM and crosslinking mass spectrometry to dissect five conformational substates of the complex, including one in which the VPS34 catalytic domain is dislodged from the complex but remains tethered by an intrinsically disordered linker...
August 3, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28731030/cryo-em-structure-and-biochemical-analysis-reveal-the-basis-of-the-functional-difference-between-human-pi3kc3-c1-and-c2
#10
Meisheng Ma, Jun-Jie Liu, Yan Li, Yuwei Huang, Na Ta, Yang Chen, Hua Fu, Ming-Da Ye, Yuehe Ding, Weijiao Huang, Jia Wang, Meng-Qiu Dong, Li Yu, Hong-Wei Wang
Phosphatidylinositol 3-phosphate (PI3P) plays essential roles in vesicular trafficking, organelle biogenesis and autophagy. Two class III phosphatidylinositol 3-kinase (PI3KC3) complexes have been identified in mammals, the ATG14L complex (PI3KC3-C1) and the UVRAG complex (PI3KC3-C2). PI3KC3-C1 is crucial for autophagosome biogenesis, and PI3KC3-C2 is involved in various membrane trafficking events. Here we report the cryo-EM structures of human PI3KC3-C1 and PI3KC3-C2 at sub-nanometer resolution. The two structures share a common L-shaped overall architecture with distinct features...
August 2017: Cell Research
https://www.readbyqxmd.com/read/28719180/heterologous-expression-purification-and-functional-analysis-of-plasmodium-falciparum-phosphatidylinositol-3-kinase
#11
Matthew R Hassett, Anna R Sternberg, Bryce E Riegel, Craig J Thomas, Paul D Roepe
The Plasmodium falciparum malarial parasite genome appears to encode one and only one phosphatidylinositol 3'-kinase (PI3K), and sequence analysis suggests that the enzyme is a "class III"- or "Vps34"-type PI3K. PfVps34 has generated excitement as a possible druggable target and potentially a key target of artemisinin-based antimalarials. In this study, we optimize the PfVps34 gene for heterologous expression in yeast, purify the protein to homogeneity, use a recently validated quantitative assay for phosphatidylinositol 3'-phosphate production from phosphatidylinositol ( Hassett et al...
August 22, 2017: Biochemistry
https://www.readbyqxmd.com/read/28716903/autophagy-related-protein-vps34-controls-the-homeostasis-and-function-of-antigen-cross-presenting-cd8%C3%AE-dendritic-cells
#12
Vrajesh V Parekh, Sudheer K Pabbisetty, Lan Wu, Eric Sebzda, Jennifer Martinez, Jianhua Zhang, Luc Van Kaer
The class III PI3K Vacuolar protein sorting 34 (Vps34) plays a role in both canonical and noncanonical autophagy, key processes that control the presentation of antigens by dendritic cells (DCs) to naive T lymphocytes. We generated DC-specific Vps34-deficient mice to assess the contribution of Vps34 to DC functions. We found that DCs from these animals have a partially activated phenotype, spontaneously produce cytokines, and exhibit enhanced activity of the classic MHC class I and class II antigen-presentation pathways...
August 1, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28706153/inhibitor-of-growth-protein-4-interacts-with-beclin-1-and-represses-autophagy
#13
Valentina Sica, José Manuel Bravo-San Pedro, Guo Chen, Guillermo Mariño, Sylvie Lachkar, Valentina Izzo, Maria Chiara Maiuri, Mireia Niso-Santano, Guido Kroemer
Beclin 1 (BECN1) is a multifunctional protein that activates the pro-autophagic class III phosphatidylinositol 3-kinase (PIK3C3, best known as VPS34), yet also interacts with multiple negative regulators. Here we report that BECN1 interacts with inhibitor of growth family member 4 (ING4), a tumor suppressor protein that is best known for its capacity to interact with the tumor suppressor protein p53 (TP53) and the acetyltransferase E1A binding protein p300 (EP300). Removal of TP53 or EP300 did not affect the BECN1/ING4 interaction, which however was lost upon culture of cells in autophagy-inducing, nutrient free conditions...
July 6, 2017: Oncotarget
https://www.readbyqxmd.com/read/28678742/chronic-myeloid-leukemia-progenitor-cells-require-autophagy-when-leaving-hypoxia-induced-quiescence
#14
Angela Ianniciello, Amélie Guitart, Pierre-Yves Dumas, Claire Drullion, Arnaud Villacreces, Yan Peytour, Jean Chevaleyre, Philippe Brunet de la Grange, Isabelle Vigon, Vanessa Desplat, Muriel Priault, Persio Dello Sbarba, Zoran Ivanovic, François-Xavier Mahon, Jean-Max Pasquet
Albeit tyrosine kinase inhibitors anti-Abl used in Chronic Myeloid Leukemia (CML) block the deregulated activity of the Bcr-Abl tyrosine kinase and induce remission in 90% of patients, they do not eradicate immature hematopoietic compartments of leukemic stem cells. To elucidate if autophagy is important for stem cell survival and/or proliferation, we used culture in low oxygen concentration (0.1% O2 for 7 days) followed back by non-restricted O2 supply (normoxic culture) to mimic stem cell proliferation and commitment...
June 30, 2017: Oncotarget
https://www.readbyqxmd.com/read/28650718/subversion-of-rab5-regulated-autophagy-by-the-intracellular-pathogen-ehrlichia-chaffeensis
#15
Yasuko Rikihisa
Intracellular pathogens often exploit RAB functions to establish a safe haven in which to survive and proliferate. Ehrlichia chaffeensis, an obligatory intracellular bacterium, resides in specialized membrane-bound inclusions that have early endosome-like characteristics, e.g., resident RAB5 GTPase and RAB5 effectors, including VPS34 (the catalytic subunit of class III phosphatidylinositol 3-kinase), but the inclusions lack late endosomal or lysosomal markers. Within inclusions, Ehrlichia obtains host-derived nutrients by inducing RAB5-regulated autophagy using Ehrlichia translocated factor-1 deployed by its type IV secretion system...
June 26, 2017: Small GTPases
https://www.readbyqxmd.com/read/28617998/schwann-cell-specific-deletion-of-the-endosomal-pi-3-kinase-vps34-leads-to-delayed-radial-sorting-of-axons-arrested-myelination-and-abnormal-erbb2-erbb3-tyrosine-kinase-signaling
#16
Anne M Logan, Anna E Mammel, Danielle C Robinson, Andrea L Chin, Alec F Condon, Fred L Robinson
The PI 3-kinase Vps34 (Pik3c3) synthesizes phosphatidylinositol 3-phosphate (PI3P), a lipid critical for both endosomal membrane traffic and macroautophagy. Human genetics have implicated PI3P dysregulation, and endosomal trafficking in general, as a recurring cause of demyelinating Charcot-Marie-Tooth (CMT) peripheral neuropathy. Here, we investigated the role of Vps34, and PI3P, in mouse Schwann cells by selectively deleting Vps34 in this cell type. Vps34-Schwann cell knockout (Vps34(SCKO) ) mice show severe hypomyelination in peripheral nerves...
September 2017: Glia
https://www.readbyqxmd.com/read/28544137/phenotypic-identification-of-a-novel-autophagy-inhibitor-chemotype-targeting-lipid-kinase-vps34
#17
Lucas Robke, Luca Laraia, Marjorie A Carnero Corrales, Georgios Konstantinidis, Makoto Muroi, André Richters, Michael Winzker, Tobias Engbring, Stefano Tomassi, Nobumoto Watanabe, Hiroyuki Osada, Daniel Rauh, Herbert Waldmann, Yao-Wen Wu, Julian Engel
Autophagy is a critical regulator of cellular homeostasis and metabolism. Interference with this process is considered a new approach for the treatment of disease, in particular cancer and neurological disorders. Therefore, novel small-molecule autophagy modulators are in high demand. We describe the discovery of autophinib, a potent autophagy inhibitor with a novel chemotype. Autophinib was identified by means of a phenotypic assay monitoring the formation of autophagy-induced puncta, indicating accumulation of the lipidated cytosolic protein LC3 on the autophagosomal membrane...
May 22, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28542134/phosphorylated-cav1-activates-autophagy-through-an-interaction-with-becn1-under-oxidative-stress
#18
Jihoon Nah, Seung-Min Yoo, Sunmin Jung, Eun Il Jeong, Moonju Park, Bong-Kiun Kaang, Yong-Keun Jung
CAV1/Caveolin1, an integral membrane protein, is involved in caveolae function and cellular signaling pathways. Here, we report that CAV1 is a positive regulator of autophagy under oxidative stress and cerebral ischemic injury. Treatment with hydrogen peroxide enhanced autophagy flux and caused the localization of BECN1 to the mitochondria, whereas these changes were impaired in the absence of CAV1. Among many autophagy signals, only LC3 foci formation in response to hydrogen peroxide was abolished by CAV1 deficiency...
May 25, 2017: Cell Death & Disease
https://www.readbyqxmd.com/read/28515304/reactive-oxygen-species-mediated-c-jun-nh2-terminal-kinase-activation-contributes-to-hepatitis-b-virus-x-protein-induced-autophagy-via-regulation-of-the-beclin-1-bcl-2-interaction
#19
Linmao Zhong, Wangqin Shu, Wangbin Dai, Bo Gao, Sidong Xiong
Autophagy is closely associated with the regulation of hepatitis B virus (HBV) replication. HBV X protein (HBx), a multifunctional regulator in HBV-associated biological processes, has been demonstrated to be crucial for autophagy induction by HBV. However, the molecular mechanisms of autophagy induction by HBx, especially the signaling pathways involved, remain elusive. In the present investigation, we demonstrated that HBx induced autophagosome formation independently of the class I phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR signaling pathway...
August 1, 2017: Journal of Virology
https://www.readbyqxmd.com/read/28498820/lysosomal-regulation-of-cholesterol-homeostasis-in-tuberous-sclerosis-complex-is-mediated-via-npc1-and-ldl-r
#20
Harilaos Filippakis, Nicola Alesi, Barbara Ogorek, Julie Nijmeh, Damir Khabibullin, Catherine Gutierrez, Alexander J Valvezan, James Cunningham, Carmen Priolo, Elizabeth P Henske
Tuberous sclerosis complex (TSC) is a multisystem disease associated with hyperactive mTORC1. The impact of TSC1/2 deficiency on lysosome-mediated processes is not fully understood. We report here that inhibition of lysosomal function using chloroquine (CQ) upregulates cholesterol homeostasis genes in TSC2-deficient cells. This TSC2-dependent transcriptional signature is associated with increased accumulation and intracellular levels of both total cholesterol and cholesterol esters. Unexpectedly, engaging this CQ-induced cholesterol uptake pathway together with inhibition of de novo cholesterol synthesis allows survival of TSC2-deficient, but not TSC2-expressing cells...
June 13, 2017: Oncotarget
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