Amentoflavone induces cell autophagy through promoting phosphorylation of ULK1 in hepatocellular carcinoma
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE221340 | GEO | 2024/12/04
REPOSITORIES: GEO
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Project description:Amentoflavone induces cell autophagy through promoting phosphorylation of ULK1 in hepatocellular carcinoma
| PRJNA913926 | ENA
Project description:Reactive oxygen species (ROS) act as a signaling intermediate to promote cellular adaptation to maintain homeostasis by regulating autophagy during pathophysiological stress. However, the mechanism by which ROS promotes autophagy is still largely unknown. Here, we show that the ATM/CHK2/ULK1 axis initiates autophagy to maintain cellular homeostasis by sensing ROS signaling under metabolic stress. We report that ULK1 is a physiological substrate of CHK2, and that the binding of CHK2 to ULK1 depends on the ROS signal and the phosphorylation of threonine 68 of CHK2 under metabolic stress. Further, CHK2 phosphorylates ULK1 on serine 556, and this phosphorylation is dependent on the ATM/CHK2 signaling pathway. CHK2-mediated phosphorylation of ULK1 promotes autophagic flux and inhibits apoptosis induced by metabolic stress. Taken together, these results demonstrate that the ATM/CHK2/ULK1 axis initiates an autophagic adaptive response by sensing ROS, and it protects cells from metabolic stress-induced cellular damage.
| S-EPMC9219861 | biostudies-literature
Project description:Autophagy is a process by which components of the cell are degraded to maintain essential activity and viability in response to nutrient limitation. Extensive genetic studies have shown that the yeast ATG1 kinase has an essential role in autophagy induction. Furthermore, autophagy is promoted by AMP activated protein kinase (AMPK), which is a key energy sensor and regulates cellular metabolism to maintain energy homeostasis. Conversely, autophagy is inhibited by the mammalian target of rapamycin (mTOR), a central cell-growth regulator that integrates growth factor and nutrient signals. Here we demonstrate a molecular mechanism for regulation of the mammalian autophagy-initiating kinase Ulk1, a homologue of yeast ATG1. Under glucose starvation, AMPK promotes autophagy by directly activating Ulk1 through phosphorylation of Ser 317 and Ser 777. Under nutrient sufficiency, high mTOR activity prevents Ulk1 activation by phosphorylating Ulk1 Ser 757 and disrupting the interaction between Ulk1 and AMPK. This coordinated phosphorylation is important for Ulk1 in autophagy induction. Our study has revealed a signalling mechanism for Ulk1 regulation and autophagy induction in response to nutrient signalling.
| S-EPMC3987946 | biostudies-literature
Project description:In order to understand the contribution of autophagy and alternative NF-kappaB signalling to transcriptional output in A549 lung cancer cells, RNAi was used to knockdown the expression of core autophagy genes (ATG5, ULK1) or the key subunit of alternative NF-kappaB RELB. Seven samples were prepared for each biological replicate; two sequence independent non-targeting control siRNAs were transfected as a negative control. Three sequence independent siRNAs targeting the core autophagy machinery were transfected (ATG5 si, ATG5 si(2), ULK1 si). N.B. ATG5 si(2) only partially ablates Atg5 protein expression whereas ATG si has greater efficacy. Two sequence independent siRNAs targeting RELB were transfected (RELB si, RELB si(2) ). Three independent biological replicates of all conditions were obtained, by performance of the experiment on different days.
2015-09-18 | E-GEOD-73158 | biostudies-arrayexpress
Project description:Autophagy is a catabolic process during which cytosolic material is enwrapped in a newly formed double-membrane structure called the autophagosome, and subsequently targeted for degradation in the lytic compartment of the cell. The fusion of autophagosomes with the lytic compartment is a tightly regulated step and involves membrane-bound SNARE proteins. These play a crucial role as they promote lipid mixing and fusion of the opposing membranes. Among the SNARE proteins implicated in autophagy, the essential SNARE protein YKT6 is the only SNARE protein that is evolutionarily conserved from yeast to humans. Here, we show that alterations in YKT6 function, in both mammalian cells and nematodes, produce early and late autophagy defects that result in reduced survival. Moreover, mammalian autophagosomal YKT6 is phospho-regulated by the ULK1 kinase, preventing premature bundling with the lysosomal SNARE proteins and thereby inhibiting autophagosome-lysosome fusion. Together, our findings reveal that timely regulation of the YKT6 phosphorylation status is crucial throughout autophagy progression and cell survival.
| S-EPMC10022743 | biostudies-literature
Project description:The molecular chaperone Hsp90 is involved in the stability and activity of its client proteins which largely comprise of kinases. Phosphorylation of Hsp90 by these kinase clients provides a reciprocal regulatory mechanism between these proteins, however the mechanism of regulating the cellular pathway remains elusive. Here, we show that the serine/threonine kinase Atg1(yeast)/ULK1(mammalian) phosphorylates a conserved serine in the amino-domain of Hsp90 and reduces its ATPase activity hence lowers chaperone function. Broadly this modification negatively impacts the chaperoning of the kinase clients including Atg1/ULK1, yet enhances the activity of the non-kinase clients such as the heat shock factor and the steroid hormone receptors. Interestingly, ATG1/ULK1 mediated phosphorylation of the Hsp90 is essential for initiation of autophagy since yeast expressing a non-phosphorylatable Hsp90 were unable to undergo autophagy and the phosphomimetic Hsp90 mutants were underwent autophagy even in the absence of stimulus. Our findings provide a new paradigm where kinase client mediated phosphorylation of Hsp90 not only regulates the chaperone function but it is essential to initiate and regulate the relevant signaling pathway.
2023-09-08 | PXD038924 | Pride
Project description:In order to understand the contribution of autophagy and alternative NF-kappaB signalling to transcriptional output in A549 lung cancer cells, RNAi was used to knockdown the expression of core autophagy genes (ATG5, ULK1) or the key subunit of alternative NF-kappaB RELB.
2015-09-18 | GSE73158 | GEO
Project description:Background: Autophagy plays an essential role in the occurrence and progression of Necrotizing enterocolitis (NEC). We purposed to carry out the identification and validation of the probable autophagy-related genes of NEC via bioinformatics methods and experiment trials. Methods: The autophagy-related differentially expressed genes (arDEGs) of NEC were identified by analyzing the RNA sequencing data of experiment neonatal mouse model and dataset GSE46619. Protein-protein interactions (PPI), gene-ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were used for the arDEGs. Then, co-expressed autophagy-related genes in two datasets were identified by Venn analysis and verified by qRT-PCR in experimental NEC. Results: Autophagy increased in experimental NEC and 47 arDEGs were identified in experimental NEC by RNA-sequencing. The PPI results proclaimed those genes interplayed with each other. The GO and KEGG enrichment results of arDEGs reported some certain enriched pathways related to autophagy and macroautophagy. Furthermore, 22 arDEGs were identified in human NEC from dataset GSE46619. The GO and KEGG enrichment analysis of these genes showed similar enriched terms with the results in experimental NEC. Finally, HIF-1a, VEGFA, ITGA3, ITGA6, ITGB4 and NAMPT were identified as co-expressed autophagy-related genes by Venn analysis in human NEC from dataset GSE46619 and experimental NEC. The result of qRT-PCR revealed the expression levels of HIF-1a and ITGA3 upregulated, VEGFA and ITGB4 downregulated in experimental NEC. Conclusion: We identified 47 arDEGs in experimental NEC and 22 arDEGs in human NEC via bioinformatics analysis. HIF-1a, ITGA3, VEGFA and ITGB4 may have effects on the progression of NEC through modulating autophagy.
2022-03-11 | GSE198372 | GEO
Project description:The Unc-51 like autophagy activating kinase 1 (ULK1) complex plays a central role in the initiation stage of autophagy. However, the function of ULK1 in the late stage of autophagy is unknown. Here, we report that ULK1, a central kinase of the ULK1 complex involved in autophagy initiation, promotes autophagosome-lysosome fusion. PKC? phosphorylates ULK1 and prevents autolysosome formation. PKC? phosphorylation of ULK1 does not change its kinase activity; however, it decreases autophagosome-lysosome fusion by reducing the affinity of ULK1 for syntaxin 17 (STX17). Unphosphorylated ULK1 recruited STX17 and increased STX17's affinity towards synaptosomal-associated protein 29 (SNAP29). Additionally, phosphorylation of ULK1 enhances its interaction with heat shock cognate 70?kDa protein (HSC70) and increases its degradation through chaperone-mediated autophagy (CMA). Our study unearths a key mechanism underlying autolysosome formation, a process in which the kinase activity of PKC? plays an instrumental role, and reveals the significance of the mutual regulation of macroautophagy and CMA in maintaining the balance of autophagy.
| S-EPMC6113293 | biostudies-literature
Project description:PurposeThe uncoordinated-51 like kinase 1 (ULK1) is an important serine/threonine protein kinase involved in autophagy, especially for the initiation stage. Previous studies have shown that ULK1 could be used as a prognostic marker in predicting poor progression-free survival and a therapeutic target for hepatocellular carcinoma (HCC) when treated with sorafenib; however, its role during hepatocarcinogenesis remains to be elucidated.MethodsCCK8 and colony formation assay were used to detect cell growth ability. Western blotting was performed to determine expression level of protein. Data from public database were downloaded to analyze expression of ULK1 at mRNA level and predict survival time. RNA-seq was conducted to reveal disturbed gene profile orchestrated by ULK1 depletion. A diethylnitrosamine (DEN)-induced HCC mice model was used to uncover the role of ULK1 in hepatocarcinogenesis.ResultsULK1 was up-regulated in liver cancer tissues and cell lines, and knockdown of ULK1 promoted apoptosis and suppressed proliferation of liver cancer cells. In in vivo experiments, Ulk1 depletion attenuated starvation-induced autophagy in mice liver, reduced diethylnitrosamine (DEN)-induced hepatic tumor number and size, and prevented tumor progression. Further, RNA-seq analysis revealed a close relationship between Ulk1 and immunity with significant changes in gene sets enriched in the interleukin and interferon pathways.ConclusionULK1 deficiency prevented hepatocarcinogenesis and inhibited hepatic tumor growth, and might be a molecular target for the prevention and treatment of HCC.
| S-EPMC9983443 | biostudies-literature