Project description:The high prevalence of obesity has focused attention on defining the pathophysiological processes that underlie susceptibility or resistance to its deleterious metabolic consequences. Mice lacking translin (Tsn), a gene implicated in a variety of biological functions from transcription to microRNA degradation, display extremely high levels of adiposity, comparable to those found in well-known genetic models of obesity, such as melanocortin 4 receptor or leptin knockout (KO) mice. Although translin KO mice display increased adiposity they retain normal glucose tolerance. In contrast, wild-type (WT) mice placed on a high-fat diet until they match translin KO adiposity levels are glucose intolerant, as expected. Conversely, translin KO mice display prominent hepatic steatosis that is more severe than that of adiposity-matched WT mice. The ability of translin KO mice to retain normal glucose tolerance in the face of massive tissue expansion may be due to three factors: preferential accumulation of subcutaneous fat, reduced levels of TNF mRNA in both adipose and hepatic tissue, and elevated levels of plasma adiponectin. Further studies aimed at defining the molecular bases for these phenotypes may yield new approaches to limit the adverse metabolic consequences of obesity.
Project description:The endogenous RNA substrates of Translin-TRAX complexes (also known as C3POs) and how they regulate diverse biological processes remain unknown. Here we show that Translin and TRAX do not play a significant role in RNAi in the filamentous fungus Neurospora crassa. Instead, the Neurospora C3PO complex functions as a ribonuclease that removes the 5M-bM-^@M-^Y pre-tRNA fragments after the processing of pre-tRNAs by RNase P. In translin and trax mutants, 5M-bM-^@M-^Y pre-tRNA fragments accumulate to very high levels that can be degraded specifically by both recombinant and endogenous Neurospora C3PO and recombinant Drosophila C3PO. In addition, the mutants have elevated tRNA levels and increased levels of protein translation and are more resistant to a programmed cell-death inducing agent. Together, this study identified the endogenous RNA substrates of C3PO and provides a potential explanation for its roles in seemingly diverse biological processes. Examine small RNA population changes in two different strain background
Project description:The endogenous RNA substrates of Translin-TRAX complexes (also known as C3POs) and how they regulate diverse biological processes remain unknown. Here we show that Translin and TRAX do not play a significant role in RNAi in the filamentous fungus Neurospora crassa. Instead, the Neurospora C3PO complex functions as a ribonuclease that removes the 5’ pre-tRNA fragments after the processing of pre-tRNAs by RNase P. In translin and trax mutants, 5’ pre-tRNA fragments accumulate to very high levels that can be degraded specifically by both recombinant and endogenous Neurospora C3PO and recombinant Drosophila C3PO. In addition, the mutants have elevated tRNA levels and increased levels of protein translation and are more resistant to a programmed cell-death inducing agent. Together, this study identified the endogenous RNA substrates of C3PO and provides a potential explanation for its roles in seemingly diverse biological processes.
Project description:Neurons utilize RNA interference in the reversible translational repression of synaptically localized mRNAs, enabling rapid translation in response to synaptic activity. Two evolutionarily conserved proteins, Translin and Trax, form an RNase complex which processes miRNAs, tRNAs and siRNAs. To determine the specific role of the RNase activity of this complex in brain function, we employed a mouse line harboring a point mutation in Trax (E126A) that renders the Translin/Trax RNase inactive. At the molecular level, we found alterations in the levels of multiple small RNAs including miRNAs, tsRNAs and substantial downregulation of gene expression at the mRNA level in the hippocampus of TraxE126A mice. At the synaptic level, TraxE126A mice exhibit deficits in specific forms of long-term hippocampal synaptic plasticity. At the behavioral level, TraxE126A mice display impaired long-term spatial memory and altered open-field and acoustic-startle behavior. These studies reveal the functional role of Translin/Trax RNase in the mammalian brain.
Project description:Neurons utilize RNA interference in the reversible translational repression of synaptically localized mRNAs, enabling rapid translation in response to synaptic activity. Two evolutionarily conserved proteins, Translin and Trax, form an RNase complex which processes miRNAs, tRNAs and siRNAs. To determine the specific role of the RNase activity of this complex in brain function, we employed a mouse line harboring a point mutation in Trax (E126A) that renders the Translin/Trax RNase inactive. At the molecular level, we found alterations in the levels of multiple small RNAs including miRNAs, tsRNAs and substantial downregulation of gene expression at the mRNA level in the hippocampus of TraxE126A mice. At the synaptic level, TraxE126A mice exhibit deficits in specific forms of long-term hippocampal synaptic plasticity. At the behavioral level, TraxE126A mice display impaired long-term spatial memory and altered open-field and acoustic-startle behavior. These studies reveal the functional role of Translin/Trax RNase in the mammalian brain.
Project description:RNA interference is required to form the centromeric heterochromatin needed for chromosome segregation fidelity. Central to this is Argonaute protein, which processes small interfering RNAs (siRNAs) within a self-enforcing feedback mechanism that utilizes the guidance of siRNAs to nucleate heterochromatin-mediators. siRNA processing by Argonaute-containing complexes is enhanced by Translin and Trax proteins. Current dogma purports that impairment of Argonaute drives centromeric heterochromatin dysregulation and chromosome instability. We used the fission yeast to demonstrate that loss of Trax can suppress the chromosomal instability conferred by loss of Argonaute in a Translin-dependent fashion, without restoring centromeric heterochromatin. Extended analysis of Trax and Translin defective cells revealed a conserved role for Trax and Translin in telomeric transcription. This not only identified a novel telomere regulatory activity, but also demonstrates that under conditions of centromeric dysfunction telomeric transcriptional stasis can negatively impact chromosome segregation.
Project description:ObjectiveDeletion of Translin (Tsn) from mice induces an unusual metabolic profile characterized by robust adiposity, normal body weight and glucose tolerance. Translin (TN) protein and its partner, trax (TX), form the TN/TX microRNA-degrading enzyme. Since the microRNA system plays a prominent role in regulating metabolism, we reasoned that the metabolic profile displayed by Tsn KO mice might reflect dysregulation of microRNA signaling.MethodsTo test this hypothesis, we inserted a mutation, E126A, in Tsnax, the gene encoding TX, that abolishes the microRNA-degrading enzymatic activity of the TN/TX complex. In addition, to help define the cell types that drive the adiposity phenotype, we have also generated mice with floxed alleles of Tsn or Tsnax.ResultsIntroduction of the E126A mutation in Tsnax does not impair expression of TN or TX proteins or their co-precipitation. Furthermore, these mice display selective increases in microRNAs that match those induced by Tsn deletion, confirming that this mutation in Tsnax inactivates the microRNA-degrading activity of the TN/TX complex. Mice homozygous for the Tsnax (E126A) mutation display a metabolic profile that closely mimics that of Tsn KO mice. Selective deletion of Tsn or Tsnax from either adipocytes or hepatocytes, two candidate cell types, does not phenocopy the elevated adiposity displayed by mice with constitutive Tsn deletion or the Tsnax (E126A) mutation. Furthermore, global, conditional deletion of Tsn in adulthood does not elicit increased adiposity.ConclusionTaken together, these findings indicate that inactivation of the TN/TX microRNA-degrading enzyme during development is necessary to drive the robust adiposity displayed by Tsn KO mice.
Project description:This first-in-human (FIH) dose-escalation and dose-validation/expansion study will assess KO-2806, a farnesyl transferase inhibitor (FTI), as a monotherapy and in combination, in adult patients with advanced solid tumors.
Project description:We previously identified Keratinocyte-associated protein 3, Krtcap3, as an obesity-related gene in female rats where a whole-body Krtcap3 knock-out (KO) led to increased adiposity compared to wild-type (WT) controls when fed a high-fat diet (HFD). We sought to replicate this work to better understand the function of Krtcap3 but were unable to reproduce the adiposity phenotype. In the current work, WT female rats ate more compared to WT in the prior study, with corresponding increases in body weight and fat mass, while there were no changes in these measures in KO females between the studies. The prior study was conducted before the COVID-19 pandemic, while the current study started after initial lock-down orders and was completed during the pandemic with a generally less stressful environment. We hypothesize that the environmental changes impacted stress levels and may explain the failure to replicate our results. Analysis of corticosterone (CORT) at euthanasia showed a significant study by genotype interaction where WT had significantly higher CORT relative to KO in Study 1, with no differences in Study 2. These data suggest that decreasing Krtcap3 expression may alter the environmental stress response to influence adiposity. We also found that KO rats in both studies, but not WT, experienced a dramatic increase in CORT after their cage mate was removed, suggesting a separate connection to social behavioral stress. Future work is necessary to confirm and elucidate the finer mechanisms of these relationships, but these data indicate the possibility of Krtcap3 as a novel stress gene.