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.
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:Expression phospho-mimic TRBP enhanced in vitro miRNA production and cellular expression of ectopic miRNA. We used miRNA microarray experiments to determine the effect of expression of phopsho-mimic TRBP on global endogenous miRNA expression.
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. Examine expression of mRNAs and miRNAs in wild-type and Trbp-cKO hearts
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: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:Expression phospho-mimic TRBP enhanced in vitro miRNA production and cellular expression of ectopic miRNA. We used miRNA microarray experiments to determine the effect of expression of phopsho-mimic TRBP on global endogenous miRNA expression. We established isogenic cell lines stably expressing phospho-mutant and phospho-mimic TRBP using Flp-In 293 cells and a Flp Recombinase Target system. After monoclonal cell colonies were selected, cells were cultured for two weeks. Total RNA was harvested when cells were ~75% confluent. Initial analysis was performed using one sample from each experimental group. Subsequent analysis included an additional two samples for each group. miRNA with values less than 500 were not included in analysis.
Project description:Cotton-top tamarins (CTTs) are an ideal model of human inflammatory bowel disease (IBD) because these animals develop multigenerational, lower bowel cancer. We previously isolated and characterized a novel enterohepatic Helicobacter species, Helicobacter saguini, from CTTs with IBD and documented that H. saguini infection in germfree C57BL IL-10-/- mice recapitulates IBD, suggesting that H. saguini influences IBD etiopathogenesis. In this study, we utilized a germfree IL-10-/- model to illustrate that H. saguini infection can naturally transmit and infect four generations and cause significant intestinal inflammatory pathology. Additionally, whole-genome sequencing of representative H. saguini isolates from each generation of IL-10-/- mice revealed gene mutations suggestive of multigenerational evolution. Overall, these results support that specific bacterial species with pathogenic potential, like H. saguini, are transmissible microorganisms in the etiopathogenesis of IBD in CTTs and reinforces the importance of specific microbiota in the pathogenesis of IBD in humans.IMPORTANCE While family history is a significant risk factor for developing inflammatory bowel disease (IBD), it is unclear whether the microbiome from parents is a transmissible influence on disease in their offspring. Furthermore, it is unknown whether IBD-associated microbes undergo genomic adaptations during multigenerational transmission and chronic colonization in their hosts. Herein, we show that a single bacterial species, Helicobacter saguini, isolated from a nonhuman primate species with familial IBD, is transmissible from parent to offspring in germfree IL-10-/- mice and causes multigenerational IBD. Additionally, whole-genome sequence analysis of H. saguini isolated from different mouse generations identified microevolutions in environmental interaction, nutrient metabolism, and virulence factor genes that suggest that multigenerational transmission may promote adaptations related to colonization and survival in new hosts and chronic inflammatory environments. The findings from our study highlight the importance of specific bacterial species with pathogenic potential, like H. saguini, as transmissible microorganisms in the etiopathogenesis of IBD.