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Åsa Birna Birgisdottir, Stephane Mouilleron, Zambarlal Bhujabal, Martina Wirth, Eva Sjøttem, Gry Evjen, Wenxin Zhang, Rebecca Lee, Nicola O'Reilly, Sharon A Tooze, Trond Lamark, Terje Johansen
Autophagosome formation depends on a carefully orchestrated interplay between membrane-associated protein complexes. Initiation of macroautophagy/autophagy is mediated by the ULK1 (unc-51 like autophagy activating kinase 1) protein kinase complex and the autophagy-specific class III phosphatidylinositol 3-kinase complex I (PtdIns3K-C1). The latter contains PIK3C3/VPS34, PIK3R4/VPS15, BECN1/Beclin 1 and ATG14 and phosphorylates phosphatidylinositol to generate phosphatidylinositol 3-phosphate (PtdIns3P). Here, we show that PIK3C3, BECN1 and ATG14 contain functional LIR motifs and interact with the Atg8-family proteins with a preference for GABARAP and GABARAPL1...
February 15, 2019: Autophagy
Xing Feng, Yanyan Jia, Yuyu Zhang, Fei Ma, Yuekun Zhu, Xuehui Hong, Qingxin Zhou, Ruixing He, Heng Zhang, Junfei Jin, Daxun Piao, He Huang, Qinghua Li, Xingfeng Qiu, Zhiyong Zhang
UVRAG (UV radiation resistance associated) is an important regulator of mammalian macroautophagy/autophagy by interacting with BECN1, PIK3C3, and RUBCN. Phosphorylation of UVRAG by MTORC1 negatively regulates autophagosome maturation under nutrient-enriched conditions. However, how UVRAG ubiquitination is regulated is still unknown. Here we report that UVRAG is ubiquitinated by SMURF1 at lysine residues 517 and 559, which decreases the association of UVRAG with RUBCN and promotes autophagosome maturation. However, the deubiquitinase ZRANB1 specifically cleaves SMURF1-induced K29 and K33-linked polyubiquitin chains from UVRAG, thereby increasing the binding of UVRAG to RUBCN and inhibiting autophagy flux...
January 27, 2019: Autophagy
Xiliang Du, Guowen Liu, Juan J Loor, Zhiyuan Fang, Ryan Bucktrout, Yuchen Yang, Qianqian Ye, Zhen Shi, Taiyu Shen, Xinghui Wang, Zhicheng Peng, Chenxu Zhao, Bin Lv, Dongmei Xing, Yiwei Zhu, Xiaobing Li, Xinwei Li
The ability of liver to respond to changes in nutrient availability is essential for the maintenance of metabolic homeostasis. Autophagy encompasses mechanisms of cell survival, including capturing, degrading, and recycling of intracellular proteins and organelles in lysosomes. During negative nutrient status, autophagy provides substrates to sustain cellular metabolism and hence, tissue function. Severe negative energy balance in dairy cows is associated with fatty liver. The aim of this study was to investigate the hepatic autophagy status in dairy cows with severe fatty liver and to determine associations with biomarkers of liver function and inflammation...
October 10, 2018: Journal of Dairy Science
Christine M Fillmore, Chunxiao Xu, Pooja T Desai, Joanne M Berry, Samuel P Rowbotham, Yi-Jang Lin, Haikuo Zhang, Victor E Marquez, Peter S Hammerman, Kwok-Kin Wong, Carla F Kim
We wish to correct two mutations in Supplementary Table 4 of this Letter. The NCI-H460 cell line was annotated as being mutant for TP53. NCI-H460 has been verified to be TP53 wild type by several sources1 . The NCI-H2009 cell line was annotated as being mutant for PIK3CA. As annotated by COSMIC (ref. 24 of the original Letter) and CCLE (ref. 25 of the original Letter), the NCI-H2009 cell line has a mutation in PIK3C3, rather than PIK3CA. The cell line is wild type for PIK3CA. The Supplementary Information of this Amendment contains the corrected Supplementary Table 4...
September 24, 2018: Nature
Tianyu Han, Meng Guo, Mingxi Gan, Bentong Yu, Xiaoli Tian, Jian-Bin Wang
Macroautophagy/autophagy is a multistep cellular process that sequesters cytoplasmic components for lysosomal degradation. BECN1/Beclin1 is a central protein that assembles cofactors for the formation of a BECN1-PIK3C3-PIK3R4 complex to trigger the autophagy protein cascade. Discovering the regulators of BECN1 is important for understanding the mechanism of autophagy induction. Here, we demonstrate that TRIM59, a tripartite motif protein, plays an important role in autophagy regulation in non-small cell lung cancer (NSCLC)...
2018: Autophagy
Angel F Corona Velazquez, William T Jackson
Autophagy is an evolutionary conserved, degradative process from single-cell eukaryotes, such as Saccharomyces cerevisiae , to higher mammals, such as humans. The regulation of autophagy has been elucidated through the combined study of yeast, Caenorhabditis elegans , mice, Drosophila melanogaster , and humans. MTOR, the major negative regulator of autophagy, and activating nutrient kinases, such as 5'-AMP-activated protein kinase (AMPK), interact with the autophagy regulatory complex: ULK1/2, RB1CC1, ATG13, and ATG101...
November 1, 2018: Molecular and Cellular Biology
Mahmoud Ahmed, Trang Huyen Lai, Sahib Zada, Jin Seok Hwang, Trang Minh Pham, Miyong Yun, Deok Ryong Kim
Raf kinase inhibitor protein (RKIP) plays a critical role in many signaling pathways as a multi-functional adapter protein. In particular, the loss of RKIP's function in certain types of cancer cells results in epithelial to mesenchymal transition (EMT) and the promotion of cancer metastasis. In addition, RKIP inhibits autophagy by modulating LC3-lipidation and mTORC1. How the RKIP-dependent inhibition of autophagy is linked to EMT and cancer progression is still under investigation. In this study, we investigated the ways by which RKIP interacts with key gene products in EMT and autophagy during the progression of prostate cancer...
August 16, 2018: Cancers
Jiaqi Li, Yuzhi Zhou, Guanhua Du, Xuemei Qin, Li Gao
Background Aging is a complex process accompanied with the decline of the different physiological functions. Numerous differentially expressed genes (DEGs) have been found in the aging brain of senescence-accelerated mouse P8 (SAMP8), however, it was challenging to screen out the crucial ones. Objective This study aimed to explore the crucial genes and pathways in aging brain of SAMP8 mice, which would be beneficial for understanding the pathogenesis of brain aging. Method Firstly, 430 genes that are differentially expressed in SAMP8 mice versus SAMR1 mice were obtained from 9 gene expression studies, and gene-gene network was constructed...
August 15, 2018: CNS & Neurological Disorders Drug Targets
Hei Sung Kim, Seo-Yeon Park, Seok Hoon Moon, Jeong Deuk Lee, Sungjoo Kim
Autophagy is an intracellular stress response that is enhanced under starvation conditions, and also when the cellular components are damaged. Aging accompanies an increase in intracellular stress and has significant impact on the skin. Since dermal fibroblasts are a powerful indicator of skin aging, we compared the autophagic activity of human skin fibroblasts between the young and old. According to TEM analyses, the number of autophagosomes per 1 μm² cytoplasmic area was similar between young and aged fibroblasts...
August 1, 2018: International Journal of Molecular Sciences
Shaoyang Zhao, Jianhong Xia, Xiuhua Wu, Leilei Zhang, Pengtao Wang, Haiyun Wang, Heying Li, Xiaoshan Wang, Yan Chen, Jean Agnetti, Yinxiong Li, Duanqing Pei, Xiaodong Shu
The class III PI3-kinase (PIK3C3) is an enzyme responsible for the generation of phosphatidylinositol 3-phosphate (PI3P), a critical component of vesicular membrane. Here, we report that PIK3C3 deficiency in zebrafish results in intestinal injury and inflammation. In pik3c3 mutants, gut tube forms but fails to be maintained. Gene expression analysis reveals that barrier-function-related inflammatory bowel disease (IBD) susceptibility genes (e-cadherin, hnf4a, ttc7a) are suppressed, while inflammatory response genes are stimulated in the mutants...
July 6, 2018: Nature Communications
Morag R Hunter, Geoffrey G Hesketh, Tomasz H Benedyk, Anne-Claude Gingras, Stephen C Graham
Multi-subunit tethering complexes control membrane fusion events in eukaryotic cells. Class C core vacuole/endosome tethering (CORVET) and homotypic fusion and vacuole protein sorting (HOPS) are two such complexes, both containing the Sec1/Munc18 protein subunit VPS33A. Metazoans additionally possess VPS33B, which has considerable sequence similarity to VPS33A but does not integrate into CORVET or HOPS complexes and instead stably interacts with VIPAR. It has been recently suggested that VPS33B and VIPAR comprise two subunits of a novel multi-subunit tethering complex (named "CHEVI"), perhaps analogous in configuration to CORVET and HOPS...
July 6, 2018: Journal of Molecular Biology
Amiya Kumar Ghosh, Theresa Mau, Martin O'Brien, Raymond Yung
Adipose tissue dysfunction is associated with inflammation, metabolic syndrome and other diseases in aging. Recent work has demonstrated that compromised autophagy activity in aging adipose tissue promotes ER stress responses, contributing to adipose tissue and systemic inflammation in aging. Phosphatidylinositol 3-kinase catalytic subunit type 3 (Pik3c3) is an 887 amino acid lipid kinase that regulates intracellular membrane trafficking and autophagy activity. To address the mechanistic link between autophagy and ER stress response in aging adipose tissue, we generated a line of adipose tissue-specific Pik3c3 knock out (~mutant mice) with the Fabp4 (Fatty acid binding protein 4) promoter driven Cre recombinase system...
April 25, 2018: Aging
Yan G Zhao, Hong Zhang
The ER forms contacts with other endomembrane systems to exchange materials (e.g., calcium and lipids) and also to modulate dynamic organelle processes, including fission, cargo sorting and movement. During autophagosome formation, dynamic contacts between the ER and the phagophore membrane are crucial for phagophore expansion and closure. Little is known about the mechanisms underlying the formation and disassembly of the ER contacts. We found that the ER-localized autophagy protein EPG-3/VMP1 plays an essential role in controlling ER-phagophore dissociation and also the disassembly of ER contacts with LDs, mitochondria and endolysosomes...
2018: Autophagy
Ji-Man Park, Minchul Seo, Chang Hwa Jung, Douglas Grunwald, Matthew Stone, Neil Michael Otto, Erik Toso, Yeseul Ahn, Michael Kyba, Timothy J Griffin, LeeAnn Higgins, Do-Hyung Kim
ULK1 (unc51-like autophagy activating kinase 1) is a serine/threonine kinase that plays a key role in regulating macroautophagy/autophagy induction in response to amino acid starvation. Despite the recent progress in understanding ULK1 functions, the molecular mechanism by which ULK1 regulates the induction of autophagy remains elusive. In this study, we determined that ULK1 phosphorylates Ser30 of BECN1 (Beclin 1) in association with ATG14 (autophagy-related 14) but not with UVRAG (UV radiation resistance associated)...
2018: Autophagy
Chun-Han Chen, Chun A Changou, Tsung-Han Hsieh, Yu-Ching Lee, Cheng-Ying Chu, Kai-Cheng Hsu, Hao-Ching Wang, Yu-Chen Lin, Yan-Ni Lo, Yun-Ru Liu, Jing-Ping Liou, Yun Yen
Purpose: MPT0L145 has been developed as a FGFR inhibitor exhibiting significant anti-bladder cancer activity in vitro and in vivo via promoting autophagy-dependent cell death. Here, we aim to elucidate the underlying mechanisms. Experimental Design: Autophagy flux, morphology, and intracellular organelles were evaluated by Western blotting, transmission electron microscope, and fluorescence microscope. Molecular docking and surface plasmon resonance assay were performed to identify drug-protein interaction...
March 1, 2018: Clinical Cancer Research: An Official Journal of the American Association for Cancer Research
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...
October 27, 2017: Oncotarget
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...
December 4, 2017: Journal of Cell Biology
Chuanbin Yang, Cui-Zan Cai, Ju-Xian Song, Jie-Qiong Tan, Siva Sundara Kumar Durairajan, Ashok Iyaswamy, Ming-Yue Wu, Lei-Lei Chen, Zhenyu Yue, Min Li, Jia-Hong Lu
Alzheimer disease (AD) is the most common neurodegenerative disease characterized by the deposition of amyloid plaque in the brain. The autophagy-associated PIK3C3-containing phosphatidylinositol 3-kinase (PtdIns3K) complex has been shown to interfere with APP metabolism and amyloid beta peptide (Aβ) homeostasis via poorly understood mechanisms. Here we report that NRBF2 (nuclear receptor binding factor 2), a key component and regulator of the PtdIns3K, is involved in APP-CTFs homeostasis in AD cell models...
2017: Autophagy
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...
2018: Autophagy
Anna Chiara Nascimbeni, Patrice Codogno, Etienne Morel
Phosphatidylinositol 3-phosphate (PtdIns3P) is a key player of membrane trafficking regulation, mostly synthesized by the PIK3C3 lipid kinase. The presence of PtdIns3P on endosomes has been demonstrated; however, the role and dynamics of the pool of PtdIns3P dedicated to macroautophagy/autophagy remains elusive. Here we addressed this question by studying the mobilization of PtdIns3P in time and space during autophagosome biogenesis. We compared different dyes known to specifically detect PtdIns3P by fluorescence microscopy analysis, based on PtdIns3P-binding FYVE and PX domains, and show that these transfected dyes induce defects in endosomal dynamics as well as artificial and sustained autophagosome formation...
September 2, 2017: Autophagy
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