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https://www.readbyqxmd.com/read/28436000/foxo3a-suppression-and-vps34-activity-are-essential-to-anti-atrophic-effects-of-leucine-in-skeletal-muscle
#1
Igor L Baptista, João G Silvestre, William J Silva, Siegfried Labeit, Anselmo S Moriscot
Our aim is to gain insight into the mechanisms underlying the anti-atrophic effects of leucine, namely, the way that this amino acid can restrain the up-regulation of MuRF1 and Mafbx/Atrogin-1 in muscle atrophy. Male rats received dietary leucine supplementation for 1-3 days, during which time their hind limbs were immobilized. Our results showed that leucine inhibited Forkhead Box O3 (FoxO3a) translocation to cell nuclei. In addition, leucine was able to reverse the expected reduction of FoXO3a ubiquitination caused by immobilization...
April 24, 2017: Cell and Tissue Research
https://www.readbyqxmd.com/read/28376509/activation-of-g%C3%AE-q-in-cardiomyocytes-increases-vps34-activity-and-stimulates-autophagy
#2
Shengnan Liu, Ya-Ping Jiang, Lisa M Ballou, Wei-Xing Zong, Richard Z Lin
Receptors that activate the heterotrimeric G protein Gαq are thought to play a role in the development of heart failure. Dysregulation of autophagy occurs in some pathological cardiac conditions including heart failure, but whether Gαq is involved in this process is unknown. We used a cardiomyocyte-specific transgenic mouse model of inducible Gαq activation (termed GαqQ209L) to address this question. After 7 days of Gαq activation, GαqQ209L hearts contained more autophagic vacuoles than wild type hearts...
April 2017: Journal of Cardiovascular Pharmacology
https://www.readbyqxmd.com/read/28376477/osteopontin-promotes-cell-migration-and-invasion-and-inhibits-apoptosis-and-autophagy-in-colorectal-cancer-by-activating-the-p38-mapk-signaling-pathway
#3
Ren-Hong Huang, Ying-Jun Quan, Jin-Hong Chen, Ting-Feng Wang, Ming Xu, Min Ye, Hao Yuan, Chong-Jie Zhang, Xiao-Jian Liu, Zhi-Jun Min
BACKGROUND: Osteopontin (OPN) is highly expressed in colorectal cancer (CRC) and is associated with disease progression in vivo. High levels of OPN have been demonstrated to predict low survival rates in CRC. Autophagy is a process of self-digestion, which is thought to play a significant role in carcinogenesis. However, the mechanisms of OPN's effects on CRC cell autophagy have not been elucidated. Therefore, we aimed to investigate possible mechanisms of OPN's effects on CRC autophagy...
April 3, 2017: Cellular Physiology and Biochemistry
https://www.readbyqxmd.com/read/28351972/erbb2-regulates-autophagic-flux-to-modulate-the-proteostasis-of-app-ctfs-in-alzheimer-s-disease
#4
Bo-Jeng Wang, Guor Mour Her, Ming-Kuan Hu, Yun-Wen Chen, Ying-Tsen Tung, Pei-Yi Wu, Wen-Ming Hsu, Hsinyu Lee, Lee-Way Jin, Sheng-Ping L Hwang, Rita P-Y Chen, Chang-Jen Huang, Yung-Feng Liao
Proteolytic processing of amyloid precursor protein (APP) C-terminal fragments (CTFs) by γ-secretase underlies the pathogenesis of Alzheimer's disease (AD). An RNA interference screen using APP-CTF [99-residue CTF (C99)]- and Notch-specific γ-secretase interaction assays identified a unique ErbB2-centered signaling network that was predicted to preferentially govern the proteostasis of APP-C99. Consistently, significantly elevated levels of ErbB2 were confirmed in the hippocampus of human AD brains. We then found that ErbB2 effectively suppressed autophagic flux by physically dissociating Beclin-1 from the Vps34-Vps15 complex independent of its kinase activity...
April 11, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28306502/pacer-mediates-the-function-of-class-iii-pi3k-and-hops-complexes-in-autophagosome-maturation-by-engaging-stx17
#5
Xiawei Cheng, Xiuling Ma, Xianming Ding, Lin Li, Xiao Jiang, Zhirong Shen, She Chen, Wei Liu, Weihua Gong, Qiming Sun
Class III PI3-kinase (PI3KC3) is essential for autophagy initiation, but whether PI3KC3 participates in other steps of autophagy remains unknown. The HOPS complex mediates the fusion of intracellular vesicles to lysosome, but how HOPS specifically tethers autophagosome to lysosome remains elusive. Here, we report Pacer (protein associated with UVRAG as autophagy enhancer) as a regulator of autophagy. Pacer localizes to autophagic structures and positively regulates autophagosome maturation. Mechanistically, Pacer antagonizes Rubicon to stimulate Vps34 kinase activity...
March 16, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28302665/calpain-mobilizes-atg9-bif-1-vesicles-from-golgi-stacks-upon-autophagy-induction-by-thapsigargin
#6
Elena Marcassa, Marzia Raimondi, Tahira Anwar, Eeva-Liisa Eskelinen, Michael P Myers, Gianluca Triolo, Claudio Schneider, Francesca Demarchi
CAPNS1 is essential for stability and function of the ubiquitous calcium dependent proteases micro- and milli-calpain. Upon the inhibition of the endoplasmic reticulum Ca2+ ATPase by 100nM thapsigargin, both micro-calpain and autophagy are activated in human U2OS osteosarcoma cells in a CAPNS1 dependent manner. As reported for other autophagy triggers, thapsigargin treatment induces Golgi fragmentation and fusion of Atg9/Bif-1 containing vesicles with LC3 bodies in control cells. On the opposite, CAPNS1 depletion is coupled to an accumulation of LC3 bodies and Rab5 early endosomes...
March 16, 2017: Biology Open
https://www.readbyqxmd.com/read/28299793/foxo1-ampk-ulk1-regulates-ethanol-induced-autophagy-in-muscle-by-enhanced-atg14-association-with-the-becn1-pik3c3-complex
#7
Ly Q Hong-Brown, C Randell Brown, Maithili Navaratnarajah, Charles H Lang
BACKGROUND: Excessive alcohol (EtOH) consumption causes an imbalance in protein metabolism. EtOH impairs protein synthesis in C2C12 myoblasts via a FoxO1-AMPK-TSC2-mTORC1 pathway and also induces protein degradation. As the underlying regulatory signaling cascades for these processes are currently poorly defined, we tested the hypothesis that alcohol-induced autophagy is mediated via activation of the PIK3C3 complex that is regulated by FoxO1-AMPK. METHODS: C2C12 myoblasts were incubated with EtOH for various periods of time, and autophagy pathway-related proteins were assessed by Western blotting and immunoprecipitation...
May 2017: Alcoholism, Clinical and Experimental Research
https://www.readbyqxmd.com/read/28253972/in-vitro-characterization-of-vps34-lipid-kinase-inhibition-by-small-molecules
#8
F Fassy, C Dureuil, A Lamberton, M Mathieu, N Michot, B Ronan, B Pasquier
VPS34 is a class III phosphoinositide 3-kinase that acts on vesicle trafficking. This kinase has recently attracted significant attention because of the function it plays in the machinery involved in the early steps of autophagy. Moreover, because significant progress had been made in the optimization of specific kinase inhibitors, its potential to be targeted by catalytic inhibitors has been investigated by different groups. The aim of this review is to present the key in vitro assays necessary for characterizing inhibitors of the catalytic activity of VPS34...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28253968/study-of-ulk1-catalytic-activity-and-its-regulation
#9
B Stork, J Dengjel
During the last decade, the molecular mechanisms controlling the initiation of (macro-)autophagy have been extensively studied. Two macromolecular kinase complexes are central for the initiation of autophagy: the protein kinase unc-51-like kinase 1 (ULK1) complex and the lipid kinase VPS34/Beclin 1 complex. The serine/threonine kinase ULK1 represents the mammalian ortholog of yeast autophagy-related (Atg) protein 1 (Atg1). ULK1 is regulated by upstream nutrient- and energy-sensing kinases, and transmits these signals to the core autophagic machinery...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28253963/fluorescence-based-assays-to-analyse-phosphatidylinositol-5-phosphate-in-autophagy
#10
M Vicinanza, M J Gratian, M Bowen, D C Rubinsztein
Autophagosome formation is stimulated by VPS34-dependent PI(3)P formation and by alternative VPS34-independent pathways. We recently described that PI(5)P regulates autophagosome biogenesis and rescues autophagy in VPS34-inactivated cells, suggesting that PI(5)P contributes to canonical autophagy. Our analysis revealed a hitherto unknown functional interplay between PIKfyve and PIPK type II in controlling PI(5)P levels in the context of autophagy. Among phosphoinositides, visualization of PI(5)P in intact cells has remained difficult...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28253960/fluorescent-fyve-chimeras-to-quantify-ptdins3p-synthesis-during-autophagy
#11
S M S Yakhine-Diop, G Martínez-Chacón, R A González-Polo, J M Fuentes, M Niso-Santano
Autophagy is the major cellular process of degradation and is modulated by several signaling pathways. Phosphatidylinositol 3-kinase (PtdIns3K) class III (Vps34) and PtdIns3K class I regulate the autophagy pathway positively and negatively, respectively. Both classes of PtdIns3K participate in the synthesis of phosphatidylinositol 3-phosphate (PtdIns3P), which plays a crucial role in autophagosome biogenesis and membrane traffic. PtdIns3P is a membrane phospholipid that is associated with endogenous FYVE domain-containing proteins...
2017: Methods in Enzymology
https://www.readbyqxmd.com/read/28238651/phosphoglycerate-kinase-1-phosphorylates-beclin1-to-induce-autophagy
#12
Xu Qian, Xinjian Li, Qingsong Cai, Chuanbao Zhang, Qiujing Yu, Yuhui Jiang, Jong-Ho Lee, David Hawke, Yugang Wang, Yan Xia, Yanhua Zheng, Bing-Hua Jiang, David X Liu, Tao Jiang, Zhimin Lu
Autophagy is crucial for maintaining cell homeostasis. However, the precise mechanism underlying autophagy initiation remains to be defined. Here, we demonstrate that glutamine deprivation and hypoxia result in inhibition of mTOR-mediated acetyl-transferase ARD1 S228 phosphorylation, leading to ARD1-dependent phosphoglycerate kinase 1 (PGK1) K388 acetylation and subsequent PGK1-mediated Beclin1 S30 phosphorylation. This phosphorylation enhances ATG14L-associated class III phosphatidylinositol 3-kinase VPS34 activity by increasing the binding of phosphatidylinositol to VPS34...
March 2, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28197072/hmgb1-mediates-autophagy-dysfunction-via-perturbing-beclin1-vps34-complex-in-dopaminergic-cell-model
#13
Jinsha Huang, Jiaolong Yang, Yan Shen, Haiyang Jiang, Chao Han, Guoxin Zhang, Ling Liu, Xiaoyun Xu, Jie Li, Zhicheng Lin, Nian Xiong, Zhentao Zhang, Jing Xiong, Tao Wang
Parkinson's disease (PD), a progressive neurodegenerative disorder, is characterized by irreversible dopaminergic neuron loss and intra-neuronal α-synuclein aggregation. High mobility group box 1 (HMGB1) has been proven to be involved in autophagy dysfunction induced by α-synuclein accumulation, and the Beclin1-vacuolar protein sorting 34 (Vps34) complex is of great importance to the initiation of autophagy. Nevertheless, the concrete interaction mechanism between HMGB1, α-synuclein and autophagy remains elusive, especially in the context of PD...
2017: Frontiers in Molecular Neuroscience
https://www.readbyqxmd.com/read/28157699/berberine-induced-autophagic-cell-death-by-elevating-grp78-levels-in-cancer-cells
#14
Xiaoqin La, Lichao Zhang, Zhuoyu Li, Peng Yang, Yingying Wang
Berberine, an isoquinoline alkaloid extracted from Coptidis Rhizoma, has been shown to induce cancer cell autophagic death. Glucose regulated protein 78 (GRP78) is associated with stress-induced autophagy. However, the related mechanisms between berberine-induced cancer cell autophagy and GRP78 remain to be elucidated. Here, we report that berberine can induce autophagic cancer cell death by elevating levels of GRP78. These results further demonstrated that berberine enhanced GRP78 by suppression of ubiquitination / proteasomal degradation of GRP78 and activation of ATF6...
March 28, 2017: Oncotarget
https://www.readbyqxmd.com/read/28147319/mevastatin-blockade-of-autolysosome-maturation-stimulates-lbh589-induced-cell-death-in-triple-negative-breast-cancer-cells
#15
Zhaohu Lin, Zhuqing Zhang, Xiaoxiao Jiang, Xinhui Kou, Yong Bao, Huijuan Liu, Fanghui Sun, Shuang Ling, Ning Qin, Lan Jiang, Yonghua Yang
Histone deacetylase inhibitors (HDACi) are promising anti-cancer agents, and combining a HDACi with other agents is an attractive therapeutic strategy in solid tumors. We report here that mevastatin increases HDACi LBH589-induced cell death in triple-negative breast cancer (TNBC) cells. Combination treatment inhibited autophagic flux by preventing Vps34/Beclin 1 complex formation and downregulating prenylated Rab7, an active form of the small GTPase necessary for autophagosome-lysosome fusion. This means that co-treatment with mevastatin and LBH589 activated LKB1/AMPK signaling and subsequently inhibited mTOR...
March 14, 2017: Oncotarget
https://www.readbyqxmd.com/read/28127575/determination-of-vps34-pik3c3-activity-in-vitro-utilising-32-p-%C3%AE-atp
#16
Michael J Munson, Ian G Ganley
VPS34 is the only class III phosphatidylinositol-3-kinase (PI3K) in mammalian cells and produces the vast majority of cellular phosphatidylinositol-3-phosphate [PI(3)P]. PI(3)P is a key signalling lipid that plays many membrane trafficking roles in processes such as endocytosis and autophagy. VPS34 is a key cellular regulator, loss of function can have catastrophic effects and is embryonic lethal (Zhou et al., 2011). The levels of cellular PI(3)P can be determined by fluorescent staining techniques and can be used to monitor effects upon VPS34 activity, however it is important to verify that any changes are mediated by VPS34, particularly as alternate pathways of PI(3)P production are possible such as via class II PI3Ks (Devereaux et al...
August 20, 2016: Bio-protocol
https://www.readbyqxmd.com/read/28127574/determination-of-cellular-phosphatidylinositol-3-phosphate-pi3p-levels-using-a-fluorescently-labelled-selective-pi3p-binding-domain-px
#17
Michael J Munson, Ian G Ganley
The lipid Phosphatidylinositol-3-phosphate [PtdIns3P or PI(3)P] plays many membrane trafficking roles and is primarily produced by the Class III PI3K, VPS34. Determining the level of cellular PI(3)P however can be complex. Extraction of cellular lipids by methanol/chloroform can struggle to separate and identify distinct phospholipid species. Alternately mass spectrometry may be utilised but this requires significant set up of specialised equipment and time to utilise. Use of a PI(3)P-binding-specific recombinant protein domain is a quick method for ascertaining cellular PI(3)P levels and can also allow visualisation of sub-cellular localisation...
August 20, 2016: Bio-protocol
https://www.readbyqxmd.com/read/28097232/vps34-regulates-myofibril-proteostasis-to-prevent-hypertrophic-cardiomyopathy
#18
Hirotaka Kimura, Satoshi Eguchi, Junko Sasaki, Keiji Kuba, Hiroki Nakanishi, Shunsuke Takasuga, Masakazu Yamazaki, Akiteru Goto, Hiroyuki Watanabe, Hiroshi Itoh, Yumiko Imai, Akira Suzuki, Noboru Mizushima, Takehiko Sasaki
Hypertrophic cardiomyopathy (HCM) is a common heart disease with a prevalence of 1 in 500 in the general population. Several mutations in genes encoding cardiac proteins have been found in HCM patients, but these changes do not predict occurrence or prognosis and the molecular mechanisms underlying HCM remain largely elusive. Here we show that cardiac expression of vacuolar protein sorting 34 (Vps34) is reduced in a subset of HCM patients. In a mouse model, muscle-specific loss of Vps34 led to HCM-like manifestations and sudden death...
January 12, 2017: JCI Insight
https://www.readbyqxmd.com/read/28069131/molecular-mechanisms-of-noncanonical-autophagy
#19
N Dupont, A C Nascimbeni, E Morel, P Codogno
Macroautophagy is a lysosomal catabolic process that maintains the homeostasis of eukaryotic cells, tissues, and organisms. Macroautophagy plays important physiological roles during development and aging processes and also contributes to immune responses. The process of macroautophagy is compromised in diseases, such as cancer, neurodegenerative disorders, and diabetes. The autophagosome, the double-membrane-bound organelle that sequesters cytoplasmic material to initiate macroautophagy, is formed by the hierarchical recruitment of about 15 autophagy-related (ATG) proteins and associated proteins, such as DFCP1, AMBRA1, the class III phosphatidyl-inositol 3-kinase VPS34, and p150/VPS15...
2017: International Review of Cell and Molecular Biology
https://www.readbyqxmd.com/read/28059666/mtorc1-mediated-nrbf2-phosphorylation-functions-as-a-switch-for-the-class-iii-ptdins3k-and-autophagy
#20
Xi Ma, Shen Zhang, Long He, Yueguang Rong, Livia Wilz Brier, Qiming Sun, Rong Liu, Weiliang Fan, She Chen, Zhenyu Yue, Joungmok Kim, Kun-Liang Guan, Defa Li, Qing Zhong
NRBF2/Atg38 has been identified as the fifth subunit of the macroautophagic/autophagic class III phosphatidylinositol 3-kinase (PtdIns3K) complex, along with ATG14/Barkor, BECN1/Vps30, PIK3R4/p150/Vps15 and PIK3C3/Vps34. However, its functional mechanism and regulation are not fully understood. Here, we report that NRBF2 is a fine tuning regulator of PtdIns3K controlled by phosphorylation. Human NRBF2 is phosphorylated by MTORC1 at S113 and S120. Upon nutrient starvation or MTORC1 inhibition, NRBF2 phosphorylation is diminished...
March 4, 2017: Autophagy
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