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https://www.readbyqxmd.com/read/29089378/ph-of-endophagosomes-controls-association-of-their-membranes-with-vps34-and-ptdins-3-p-levels
#1
Amriya Naufer, Victoria E B Hipolito, Suriakarthiga Ganesan, Akriti Prashar, Vanina Zaremberg, Roberto J Botelho, Mauricio R Terebiznik
Phagocytosis of filamentous bacteria occurs through tubular phagocytic cups (tPCs) and takes many minutes to engulf these filaments into phagosomes. Contravening the canonical phagocytic pathway, tPCs mature by fusing with endosomes. Using this model, we observed the sequential recruitment of early and late endolysosomal markers to the elongating tPCs. Surprisingly, the regulatory early endosomal lipid phosphatidylinositol-3-phosphate (PtdIns(3)P) persists on tPCs as long as their luminal pH remains neutral...
October 31, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/29066608/molecular-mechanisms-of-developmentally-programmed-crinophagy-in-drosophila
#2
Tamás Csizmadia, Péter Lőrincz, Krisztina Hegedűs, Szilvia Széplaki, Péter Lőw, Gábor Juhász
At the onset of metamorphosis, Drosophila salivary gland cells undergo a burst of glue granule secretion to attach the forming pupa to a solid surface. Here, we show that excess granules evading exocytosis are degraded via direct fusion with lysosomes, a secretory granule-specific autophagic process known as crinophagy. We find that the tethering complex HOPS (homotypic fusion and protein sorting); the small GTPases Rab2, Rab7, and its effector, PLEKHM1; and a SNAP receptor complex consisting of Syntaxin 13, Snap29, and Vamp7 are all required for the fusion of secretory granules with lysosomes...
October 24, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/29030394/ptdins3p-controls-mtorc1-signaling-through-lysosomal-positioning
#3
Zhi Hong, Nina Marie Pedersen, Ling Wang, Maria Lyngaas Torgersen, Harald Stenmark, Camilla Raiborg
The mechanistic target of rapamycin complex 1 (mTORC1) is a protein kinase complex that localizes to lysosomes to up-regulate anabolic processes and down-regulate autophagy. Although mTORC1 is known to be activated by lysosome positioning and by amino acid-stimulated production of phosphatidylinositol 3-phosphate (PtdIns3P) by the lipid kinase VPS34/PIK3C3, the mechanisms have been elusive. Here we present results that connect these seemingly unrelated pathways for mTORC1 activation. Amino acids stimulate recruitment of the PtdIns3P-binding protein FYCO1 to lysosomes and promote contacts between FYCO1 lysosomes and endoplasmic reticulum that contain the PtdIns3P effector Protrudin...
October 13, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/28980854/pik3c3-vps34-control-by-acetylation
#4
Hua Su, Wei Liu
PIK3C3/VPS34 (phosphatidylinositol 3-kinase catalytic subunit type 3) converts phosphatidylinositol (PtdIns) to phosphatidylinositol-3-phosphate (PtdIns3P), sustaining macroautophagy/autophagy and endosomal transport. So far, facilitating the assembly of the PIK3C3/VPS34-BECN1-PIK3R4/VPS15/p150 core complex at distinct membranes is the only known way to activate PIK3C3/VPS34 in cells. We have recently revealed a novel mechanism that regulates PIK3C3/VPS34 activation; cellular PIK3C3/VPS34 is repressed under nutrient-rich conditions by EP300/p300-mediated acetylation...
October 5, 2017: Autophagy
https://www.readbyqxmd.com/read/28972076/secretory-autophagy-in-cancer-associated-fibroblasts-promotes-head-and-neck-cancer-progression-and-offers-a-novel-therapeutic-target
#5
Jacob New, Levi Arnold, Megha Ananth, Sameer Alvi, Mackenzie Thornton, Lauryn R Werner, Ossama Tawfik, Hongying Dai, Yelizaveta Shnayder, Kiran Kakarala, Terance Ted Tsue, Douglas A Girod, Wen-Xing Ding, Shrikant Anant, Sufi M Thomas
Despite therapeutic advancements, there has been little change in the survival of patients with head and neck squamous cell carcinoma (HNSCC). Recent results suggest that cancer-associated fibroblasts (CAF) drive progression of this disease. Here, we report that autophagy is upregulated in HNSCC-associated CAFs where it is responsible for key pathogenic contributions in this disease. Autophagy is fundamentally involved in cell degradation, but there is emerging evidence that suggests it is also important for cellular secretion...
September 28, 2017: Cancer Research
https://www.readbyqxmd.com/read/28904211/zonda-is-a-novel-early-component-of-the-autophagy-pathway-in-drosophila
#6
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...
November 1, 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
#7
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
#8
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 VPS34 (vacuolar protein sorting 34), 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...
November 2017: Arteriosclerosis, Thrombosis, and Vascular Biology
https://www.readbyqxmd.com/read/28877469/autophagy-independent-lysosomal-targeting-regulated-by-ulk1-2-fip200-and-atg9
#9
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
#10
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)...
October 2, 2017: Journal of Clinical Investigation
https://www.readbyqxmd.com/read/28846113/vps34-stimulation-of-p62-phosphorylation-for-cancer-progression
#11
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
#12
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...
September 21, 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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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