Project description:RNA silencing is a post-transcriptional gene-silencing mechanism mediated by microRNAs (miRNAs). However, the regulatory mechanism of RNA silencing during viral infection is unclear. TAR RNA-binding protein (TRBP) is an enhancer of RNA silencing that induces miRNA maturation by interacting with the ribonuclease Dicer. TRBP interacts with a virus sensor protein, laboratory of genetics and physiology 2 (LGP2), in the early stage of viral infection of human cells. Next, it induces apoptosis by inhibiting the maturation of miRNAs, thereby upregulating the expression of apoptosis regulatory genes. In this study, we show that TRBP undergoes a functional conversion in the late stage of viral infection. Viral infection resulted in the activation of caspases that proteolytically processed TRBP into two fragments. The N-terminal fragment did not interact with Dicer but interacted with type I interferon (IFN) signaling modulators, such as protein kinase R (PKR) and LGP2, and induced ER stress. The end results were irreversible apoptosis and suppression of IFN signaling. Our results demonstrate that the processing of TRBP enhances apoptosis, reducing IFN signaling during viral infection.
Project description:RNA silencing is a post-transcriptional gene-silencing mechanism mediated by microRNAs (miRNAs). However, the regulatory mechanism of RNA silencing during viral infection is unclear. TAR RNA-binding protein (TRBP) is an enhancer of RNA silencing that induces miRNA maturation by interacting with the ribonuclease Dicer. TRBP interacts with a virus sensor protein, laboratory of genetics and physiology 2 (LGP2), in the early stage of viral infection of human cells. Next, it induces apoptosis by inhibiting the maturation of miRNAs, thereby upregulating the expression of apoptosis regulatory genes. In this study, we show that TRBP undergoes a functional conversion in the late stage of viral infection. Viral infection resulted in the activation of caspases that proteolytically processed TRBP into two fragments. The N-terminal fragment did not interact with Dicer but interacted with type I interferon (IFN) signaling modulators, such as protein kinase R (PKR) and LGP2, and induced ER stress. The end results were irreversible apoptosis and suppression of IFN signaling. Our results demonstrate that the processing of TRBP enhances apoptosis, reducing IFN signaling during viral infection.
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.
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.
Project description:We generated the cardiac-specific knockout of Trbp (Trbp-cKO) in mice. We profiled the transcriptome in both wild-type and Trbp-cKO hearts, and found numerous genes were deregulated by deletion of Trbp. We also profiled miRNA expression both wild-type and Trbp-cKO hearts, and found expression of a subset of miRNA species was altered in Trbp-cKO hearts.