Amentoflavone induces cell autophagy through promoting phosphorylation of ULK1 in hepatocellular carcinoma
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ABSTRACT:
PROVIDER: PRJNA913926 | ENA |
REPOSITORIES: ENA
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Project description:Human papillomaviruses (HPVs) are conducive to a fraction of head and neck squamous cell carcinoma (HNSCC). Previously we demonstrated that HPV16 oncogene E6 or E6/E7 transduction increases the abundance of O-linked GlcNAcylation (O-GlcNAc) transferase (OGT). Herein we focus on the effects of O-GlcNAcylation on HPV-positive HNSCCs. We found that upon HPV infection, ULK1, an autophagy-initiating kinase, is hyper-O-GlcNAcylated, stabilized and linked with autophagy elevation. Through mass spectrometry, we identified that ULK1 is O-GlcNAcylated at Ser409Ser410, which is distinct from previously reported Thr635Thr754. It has been known that PKCαmediates phosphorylation of ULK1 at Ser423, which attenuates its stability by shunting ULK1 to the chaperon-mediated autophagy (CMA) pathway. By biochemical assays, we demonstrate that ULK1 Ser409Ser410 O-GlcNAcylation antagonizes its phosphorylation at pSer423. Mutations of Ser409ASer410A (2A) render ULK1 less stable by promoting interaction with the CMA chaperon Hsc70. Moreover, ULK1-2A mutants attenuate the association of ULK1 with STX17, which is vital for the fusion between autophagosomes and lysosomes. Analysis of the TCGA database reveals that ULK1 is upregulated in HPV-positive HNSCCs and its protein level positively correlates with HNSCC patient survival. Our work demonstrates that O-GlcNAcylation of ULK1 alters to reciprocate to the environmental changes. O-GlcNAcylation of ULK1 at Ser409Ser410 stabilizes ULK1, and it might underlie the molecular mechanism of HPV-positive HNSCC patient survival.
2022-10-14 | PXD031095 | Pride
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. 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.
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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:Hypoxia is a physiological stress that frequently occurs in solid tissues. Autophagy, a ubiquitous degradation/recycling system in eukaryotic cells, renders cells tolerant to multiple stressors. However, the mechanisms underlying autophagy initiation upon hypoxia remains unclear. This study identifies an oxygen-sensitive methylation of ULK1 with an important role in hypoxic stress adaptation by promoting autophagy induction.
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Project description:Activation of the STING (Stimulator of Interferon Genes) pathway by microbial or self-DNA, as well as cyclic di nucleotides (CDN), results in the induction of numerous genes that suppress pathogen replication and facilitate adaptive immunity. However, sustained gene transcription is rigidly prevented to avoid lethal STING-dependent pro-inflammatory disease by mechanisms that remain unknown. We demonstrate here that after autophagy-dependent STING delivery of TBK1 (TANK-binding kinase 1) to endosomal/lysosomal compartments and activation of transcription factors IRF3 (interferon regulatory factors 3) and NF-κB (nuclear factor kappa beta), that STING is subsequently phosphorylated by serine/threonine UNC-51-like kinase (ULK1/ATG1) and IRF3 function is suppressed. ULK1 activation occurred following disassociation from its repressor adenine monophosphate activated protein kinase (AMPK), and was elicited by CDN’S generated by the cGAMP synthase, cGAS. Thus, while CDN’s may initially facilitate STING function, they subsequently trigger negative-feedback control of STING activity, thus preventing the persistent transcription of innate immune genes. Total RNA obtained from primary STING deficient mouse embryonic fibroblast reconstituted with mSTING (W), S365A variant (A), or S365D variant (D). These cells were transfected with dsDNA (ISD) for 3 hours.
2013-10-10 | E-GEOD-51199 | biostudies-arrayexpress
Project description:Here we compare transcriptome dynamics in human lung carcinoma cells A549 infected with Influenza virus A/Port Chalmers/1/73 (H3N2) at two different virus to host cell ratios: multiplicity of infection (MOI) 1 and 5. Our goal was to outline the activation profiles of two main host pro-survival mechanisms, autophagy and mTORC2, co-opted by the virus to effectively complete the replication cycle, amplify, and release of infectious particles. We found that at high virus load MOI5 autophagy, a stress response mechanisms that postpones mammalian cell death, was activated and inhibited within 1 hour of infection. Autophagy downregulation was quickly followed by the activation of genes regulating mTORC2, a secondary cell survival mechanism promoting low capacity of cellular metabolism by inhibition of mTORC1, a main regulator of protein synthesis activating ribosomal elongation factors. At lower MOI (1) autophagy activation followed the virus replication cycle. We found that ULK1 gene expression was gradually upregulated upon Influenza virus A infection at MOI1 together with the activation of key regulators of mTORC1. Such results was not expected since mTORC1 inhibits autophagy activation pathway on post-transcription level through phosphorylation of ULK1.
2020-11-29 | GSE162295 | GEO
Project description:Activation of the STING (Stimulator of Interferon Genes) pathway by microbial or self-DNA, as well as cyclic di nucleotides (CDN), results in the induction of numerous genes that suppress pathogen replication and facilitate adaptive immunity. However, sustained gene transcription is rigidly prevented to avoid lethal STING-dependent pro-inflammatory disease by mechanisms that remain unknown. We demonstrate here that after autophagy-dependent STING delivery of TBK1 (TANK-binding kinase 1) to endosomal/lysosomal compartments and activation of transcription factors IRF3 (interferon regulatory factors 3) and NF-κB (nuclear factor kappa beta), that STING is subsequently phosphorylated by serine/threonine UNC-51-like kinase (ULK1/ATG1) and IRF3 function is suppressed. ULK1 activation occurred following disassociation from its repressor adenine monophosphate activated protein kinase (AMPK), and was elicited by CDN’S generated by the cGAMP synthase, cGAS. Thus, while CDN’s may initially facilitate STING function, they subsequently trigger negative-feedback control of STING activity, thus preventing the persistent transcription of innate immune genes.
2013-10-10 | GSE51199 | GEO
Project description:Several traumatic and neurodegenerative disorders of the CNS show axonal degeneration as a key and early pathological feature. Following a focal axonal lesion, an extended axonal disintegration by acute axonal degeneration (AAD) occurs within several hours. During AAD, activation of autophagic proteins including Unc-51 like autophagy activating kinase 1 (ULK1) has been demonstrated, but its role is incompletely understood. Here, we overexpressed a dominant negative of ULK1 (ULK1.DN) in primary rat cortical neurons in vitro and in the spinal cord (SC) and optic nerve (ON) in vivo. We found a significant inhibitory effect on autophagy in vitro and in vivo. While no effect on cell survival could be observed, ULK1.DN attenuated AAD after axotomy in microfluidic chambers in vitro. Models of SC injury and ON crush in vivo confirmed an attenuation of axonal degeneration by ULK1.DN. In a translational approach, we employed the selective ULK1 inhibitor SBI-0206965 (SBI) and found an attenuation of AAD after ON crush in vivo mediated by a reduction of autophagy by SBI. Quantitative proteomic profiling after ULK1.DN overexpression in vitro revealed a regulation of proteins associated with translation and splicing. A differential exon expression analysis identified the genes kinesin family member 1B (Kif1b), DNA damage inducible transcript 3 (Ddit3) and WD repeat domain 6 (Wdr6) as targets of ULK1.DN and potential mediators of its degeneration-attenuating effect. These findings reveal ULK1 as an important mediator of axonal degeneration and elucidate its function in splicing, defining it as a putative therapeutic target.
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