Long non-coding RNA DARS-AS1 promotes tumor progression by suppressing PACT-mediated PKR activation
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ABSTRACT:
PROVIDER: PRJNA813235 | ENA |
REPOSITORIES: ENA
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Project description:Cancer cells evolve various mechanisms to overcome cellular stresses and maintain progression. Protein kinase R (PKR) and its protein activator (PACT) are the initial responders in monitoring diverse stress signals and lead to cell proliferation inhibition and cell apoptosis in consequence. However, the regulation of PACT-PKR pathway in cancer cells is largely unknown. Herein, we identify that the long non-coding RNA (lncRNA) aspartyl-tRNA synthetase antisense RNA 1 (DARS-AS1) is directly involved in the inhibition of the PACT-PKR pathway and promotes cancer cell proliferation. Using large-scale CRISPRi functional screening of 971 cancer-associated lncRNAs, we find that DARS-AS1 is associated with significantly enhanced cancer cell proliferation. Accordingly, knocking down DARS-AS1 inhibits cell proliferation of multiple cancer cell lines and promotes cancer cell apoptosis in vitro and significantly reduces tumor growth in vivo. Mechanistically, DARS-AS1 directly binds to the activator domain of PACT and prevents PACT-PKR interaction, thereby decreasing PKR activation, eIF2α phosphorylation and inhibiting apoptotic cell death. Clinically, DARS-AS1 is broadly expressed across multiple cancers and the increased expression of this lncRNA indicates poor prognosis. This study elucidates the lncRNA DARS-AS1 directed cancer-specific modulation of the PACT-PKR pathway and provides a novel target for cancer prognosis and therapeutic treatment.
2022-05-15 | GSE197980 | GEO
Project description:TRBP has two known functions as Dicer co-factor and PKR inhibitor. However, the role of TRBP in miRNA biogenesis is controversial and its regulation of PKR in mitosis remains unexplored. Here, we generate TRBP KO HeLa cells and find that TRBP depletion alters Dicer processing sites of a subset of miRNAs, but does not affect Dicer stability, miRNA abundance, or Argonaute loading. By generating PACT, another Dicer interactor, and TRBP/PACT double-KO cells, we further show that TRBP and PACT do not functionally compensate each other and that only TRBP contributes to Dicer processing. We also report that TRBP is hyperphosphorylated by JNK in M phase when PKR is activated by cellular dsRNAs. Hyperphosphorylation potentiates the inhibitory activity of TRBP on PKR, suppressing PKR in M-G1 transition. By generating the first human TRBP KO, our study clarifies the role of TRBP and unveils negative feedback regulation of PKR through TRBP phosphorylation. small RNAs of wild type, TRBP knockout, PACT knockout and TRBP/PACT double knockout cells were sequenced by Illumina Miseq.
2014-09-16 | E-GEOD-61458 | biostudies-arrayexpress
Project description:Activation of the PI3K/Akt/mTOR pathway in cancers can occur through loss of PTEN. Transcriptional profiling of pathway inhibitors identified the tumor suppressor RhoB as a gene markedly upregulated by lipid-based Akt inhibitors (LBAI). Here, we demonstrate that the C/EBPbeta full-length isoform LAP is responsible for transcriptional induction through its binding site within the RhoB proximal promoter. LBAI strongly transactivate RhoB by switching translation of C/EBPbeta from the truncated isoform LIP to LAP via PACT-mediated PKR activation in cancer cells with high Akt activity. Unlike PTEN commonly mutated, endogenous RhoB tumor-suppressive activity can be reconstituted by restoring its expression, which was noninvasively monitored by a RhoB promoter-driven luciferase reporter in living mice. LBAI administration increased luciferase activity and decreased the growth of human tumor xenografts. Increased PKR activation by LBAI leads to more robust RhoB induction and cytotoxicity than other PI3K/Akt/mTOR axis inhibitors, revealing a novel strategy for cancer therapy.
2015-01-29 | GSE28993 | GEO
Project description:Activation of the PI3K/Akt/mTOR pathway in cancers can occur through loss of PTEN. Transcriptional profiling of pathway inhibitors identified the tumor suppressor RhoB as a gene markedly upregulated by lipid-based Akt inhibitors (LBAI). Here, we demonstrate that the C/EBPbeta full-length isoform LAP is responsible for transcriptional induction through its binding site within the RhoB proximal promoter. LBAI strongly transactivate RhoB by switching translation of C/EBPbeta from the truncated isoform LIP to LAP via PACT-mediated PKR activation in cancer cells with high Akt activity. Unlike PTEN commonly mutated, endogenous RhoB tumor-suppressive activity can be reconstituted by restoring its expression, which was noninvasively monitored by a RhoB promoter-driven luciferase reporter in living mice. LBAI administration increased luciferase activity and decreased the growth of human tumor xenografts. Increased PKR activation by LBAI leads to more robust RhoB induction and cytotoxicity than other PI3K/Akt/mTOR axis inhibitors, revealing a novel strategy for cancer therapy. H157 cells were plated 2 x 10^6 in T-75 flasks in RPMI 1640 containing 10% FBS and incubated for 24h. The medium was then changed to RPMI 1640 with 0.1% FBS and the cells were incubated overnight. The following morning, cells were treated with 10 microM of LY294002, OSU03012, PIA23, Perifosine, Miltefosine, API-2, DZ-50, or 100 nM of Wortmannin and Rapamycin for 6 hours, or an equal amount of DMSO as control. Following incubation, total RNA was extracted from cells in T-75 flasks using TRIzol reagent (Invitrogen). Two dye-swapped replicates were performed for each treatment.
2015-01-29 | E-GEOD-28993 | biostudies-arrayexpress
Project description:TRBP has two known functions as Dicer co-factor and PKR inhibitor. However, the role of TRBP in miRNA biogenesis is controversial and its regulation of PKR in mitosis remains unexplored. Here, we generate TRBP KO HeLa cells and find that TRBP depletion alters Dicer processing sites of a subset of miRNAs, but does not affect Dicer stability, miRNA abundance, or Argonaute loading. By generating PACT, another Dicer interactor, and TRBP/PACT double-KO cells, we further show that TRBP and PACT do not functionally compensate each other and that only TRBP contributes to Dicer processing. We also report that TRBP is hyperphosphorylated by JNK in M phase when PKR is activated by cellular dsRNAs. Hyperphosphorylation potentiates the inhibitory activity of TRBP on PKR, suppressing PKR in M-G1 transition. By generating the first human TRBP KO, our study clarifies the role of TRBP and unveils negative feedback regulation of PKR through TRBP phosphorylation.
2014-09-16 | GSE61458 | GEO
Project description:Stress granules (SGs) formation is a conserved cellular strategy to reduce stress-related damage regulating cell survival. A Mass spectrometry-based profiling of the interactome of PPRV N protein revealed that PPRV N interacted with PACT to regulate the assembly of SGs. N protein inhibited the interaction between PACT and a PKR inhibitor TRBP through binding to the M1 domain of PACT, which enhanced the interaction between PACT and PKR and thus promoted PKR activation and subsequent eIF2α phosphorylation as well as SGs formation. The regulatory function of N protein was strikingly abrogated in PACT-/- cells. PPRV infection-induced SGs through the PKR/eIF2α pathway are PACT-dependent. The loss of function assay indicated that PPRV-induced SGs were critical for PPRV replication. We concluded that the PPRV N protein manipulates the host PKR/eIF2α/SGs axis to favor virus replication.
2022-12-27 | PXD039104 | iProX
Project description:Exon(s) back-splicing-generated circular RNAs as a group can suppress the double-stranded RNA (dsRNA)-activated protein kinase R (PKR) in cells. We have sought to synthesize immunogenicity-free, short dsRNA-containing circular RNAs as potent PKR inhibitors. Here, we report that circular RNAs synthesized by permuted td introns from T4 bacteriophage and by Anabeana pre-tRNA group I intron induce an immune response. Mechanistically, autocatalytic splicing introduces extra ~74 nt and ~186 nt fragments (E1+E2+spacer) that form additional stable loop structures that likely provoke innate immune responses in circular RNA products. In contrast, circular RNAs produced by T4 RNA ligase without unwanted fragment exhibit little immunogenicity. Importantly, directly-ligated circular RNAs form short dsRNA-regions exhibit 103~106 fold higher efficiency than the reported chemical compounds C16 and 2-AP in suppressing PKR activation, highlighting the use of circular RNAs as novel inhibitors for PKR over-reaction diseases.
2021-12-23 | GSE183941 | GEO
Project description:The RIG-I-like receptors (RLRs: RIG-I, MDA5 and LGP2) trigger inflammatory and antiviral responses by sensing non-self RNA molecules produced during viral replication. LGP2 regulation of RIG-I and MDA5-dependant type-I interferon signaling is a matter of controversy. Here we show that LGP2 interacts with different components of the RNA silencing machinery. Particularly, we identified a direct protein-protein interaction between LGP2 and interferon-inducible double-stranded RNA-dependent protein kinase activator A (PACT). The LGP2-PACT interaction is mediated by the regulatory C-terminal domain of LGP2 and is necessary for inhibiting the RIG-I- and amplifying the MDA5-responses. We describe a point mutation within LGP2 that disrupts LGP2-PACT interaction and leads to the loss of LGP2 regulatory activity over RIG-I and MDA5. These results provide a model in which PACT-LGP2 interaction regulates RIG-I and MDA5 inflammatory response and allows cellular RNA silencing machinery to coordinate the innate immune response.
2019-10-02 | PXD013191 | Pride
Project description:TGFB2-AS1 is a long non-coding RNA which is induced by ΤGFβ signaling. In order to assess the importance of TGFB2-AS1 on the regulation of gene expression, we performed an AmpliSeq transcriptomic array in human keratinocytes (HaCaT), which stably over-express TGFB2-AS1 or control pcDNA3 empty vector. In addition, cells were stimulated with TGFβ1 for 24 hours, in order to observe the effects of TGFB2-AS1 on gene expression, downstream of TGFβ signaling. RNA from the following four conditions was used in this experiment: 1) pcDNA3, 2) pcDNA3+TGFβ1, 3) pcDNA3-TGFB2-AS1, 4) pcDNA3-TGFB2-AS1+TGFβ1. Biological triplicates were used per condition.
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Project description:Global analysis of gene expression in NIH3T3 cells over-expressing RNA-dependent serine/threonine protein kinase (PKR). Keywords: other
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