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Hepatocellular carcinoma (HCC) is an aggressive and fatal disease caused by a subset of cancer stem cells (CSCs). It is estimated that there are approximately 100 000 long noncoding RNAs (lncRNAs) in humans. However, the mechanisms by which lncRNAs affect tumor stemness remain poorly understood. In the present study, it is found that DIO3OS is a conserved lncRNA that is generally downregulated in multiple cancers, including HCC, and its low expression correlates with poor clinical outcomes in HCC. In in vitro cancer cell lines and an in vivo spontaneous HCC mouse model, DIO3OS markedly represses tumor development via its suppressive role in CSCs through downregulation of zinc finger E‐box binding homeobox 1 (ZEB1). Interestingly, DIO3OS represses ZEB1 post‐transcriptionally without affecting its mRNA levels. Subsequent experiments show that DIO3OS interacts with the NONO protein and restricts NONO‐mediated nuclear export of ZEB1 mRNA. Overall, these findings demonstrate that the DIO3OS‐NONO‐ZEB1 axis restricts HCC development and offers a valuable candidate for CSC‐targeted therapeutics for HCC. [ABSTRACT FROM AUTHOR]

Abstract: Methylation of tRNA on the four canonical bases adds structural complexity to the molecule, and improves decoding specificity and efficiency. While many tRNA methylases are known, detailed insight into the catalytic mechanism is only available in a few cases. Of interest among all tRNA methylases is the structural basis for nucleotide selection, by which the specificity is limited to a single site, or broadened to multiple sites. General themes in catalysis include the basis for rate acceleration at highly diverse nucleophilic centers for methyl transfer, using S-adenosylmethionine as a cofactor. Studies of tRNA methylases have also yielded insights into molecular evolution, particularly in the case of enzymes that recognize distinct structures to perform identical reactions at the same target nucleotide. [Copyright &y& Elsevier]

Cysteinyl‐tRNA synthetase (CysRS) is highly specific for synthesis of cysteinyl adenylate, yet does not possess the amino acid editing activity characteristic of many other tRNA synthetases. To elucidate how CysRS is able to distinguish cysteine from non‐cognate amino acids, crystal structures of the Escherichia coli enzyme were determined in apo and cysteine‐bound states. The structures reveal that the substrate cysteine thiolate forms a single direct interaction with a zinc ion bound at the base of the active site cleft, in a trigonal bipyramidal geometry together with four highly conserved protein side chains. Cysteine binding induces movement of the zinc ion towards substrate, as well as flipping of the conserved Trp205 indole ring to pack on the thiol side chain. The imidazole groups of five conserved histidines lie adjacent to the zinc ion, forming a unique arrangement suggestive of functional significance. Thus, amino acid discrimination without editing arises most directly from the favorable zinc–thiolate interaction, which is not possible for non‐cognate substrates. Additional selectivity may be generated during the induced‐fit conformational changes that help assemble the active site. [ABSTRACT FROM AUTHOR]

Detecting pancreatic duct adenocarcinoma (PDAC) in its early stages and predicting late‐stage patient prognosis undergoing chemotherapy is challenging. This work shows that the activation of specific oncogenes leads to elevated expression of mRNAs and their corresponding proteins in extracellular vesicles (EVs) circulating in blood. Utilizing an immune lipoplex nanoparticle (ILN) biochip assay, these findings demonstrate that glypican 1 (GPC1) mRNA expression in the exosomes‐rich (Exo) EV subpopulation and GPC1 membrane protein (mProtein) expression in the microvesicles‐rich (MV) EV subpopulation, particularly the tumor associated microvesicles (tMV), served as a viable biomarker for PDAC. A combined analysis effectively discriminated early‐stage PDAC patients from benign pancreatic diseases and healthy donors in sizable clinical from multiple hospitals. Furthermore, among late‐stage PDAC patients undergoing chemotherapy, lower GPC1 tMV‐mProtein and Exo‐mRNA expression before treatment correlated significantly with prolonged overall survival. These findings underscore the potential of vesicular GPC1 expression for early PDAC screenings and chemotherapy prognosis. [ABSTRACT FROM AUTHOR]

Aims The aim of this study was to investigate the involvement of the ventral intermediate nucleus of thalamus (Vim) in the tremor- and akinetic-/rigid-related networks in Parkinson's disease ( PD). Methods Tremor-dominant ( TD) and akinetic-/rigid-dominant ( ARD) PD patients were recruited and scanned by resting-state functional MRI. Functional connectivity from the Vim nucleus was analyzed. Results In the TD patients, the Vim nucleus exhibited increased connectivity with the cerebellum/dentate nucleus, primary motor cortex (M1), supplementary motor area ( SMA), premotor cortex, thalamus, globus pallidus, putamen, and parietal cortex compared with the controls, while the connections between the Vim nucleus and M1 and cerebellum/dentate nucleus had positive correlations with the tremor scores. In the ARD patients, the Vim nucleus only showed enhanced connectivity with the globus pallidus and limbic lobe compared with the controls, and no connectivity showed correlation against the akinetic-rigidity scores. TD patients had increased connectivity with the Vim nucleus in the cerebellum, M1, SMA, thalamus, globus pallidus, putamen, and parietal cortex compared with ARD patients. Conclusions This study demonstrates that the Vim nucleus has an important role in the tremor-related network, but not in the akinetic-/rigid-related network. Our finding is helpful to explain the selective effect of Vim deep brain stimulation in PD. [ABSTRACT FROM AUTHOR]

Aims Postural instability/gait difficulty ( PIGD) and tremor-dominant ( TD) subtypes of Parkinson's disease ( PD) show different clinical manifestations; however, their underlying neural substrates remain incompletely understood. This study aimed at investigating the subtype-specific patterns of spontaneous brain activity in PD. Methods Thirty-one patients with PD (12 TD/19 PIGD) and 22 healthy gender- and age-matched controls were recruited. Resting-state functional magnetic resonance imaging data were collected, and amplitude of low-frequency fluctuations ( ALFF) was measured. Voxelwise one-way analysis of covariance and post hoc analyses of ALFF were performed among the three groups, with age and gender as covariates (levodopa daily dosage and gray matter volume as additional covariates for validation analysis). Correlations of clinical variables (e.g., disease duration and PIGD/tremor subscale score) with ALFF values were examined. Results Compared with controls, patients with TD exhibited higher ALFF in the right cerebellar posterior lobe and patients with PIGD exhibited lower ALFF in the bilateral putamen and cerebellar posterior lobe, and higher values primarily in several cortical areas including the inferior and superior temporal gyrus, superior frontal, and parietal gyrus. Compared with patients with PIGD, patients with TD had higher ALFF in the bilateral putamen and the cerebellar posterior lobe, as well as lower ALFF in the bilateral temporal gyrus and the left superior parietal lobule. In all patients, ALFF in the bilateral cerebellar posterior lobe positively correlated with tremor score and ALFF in the bilateral putamen negatively correlated with PIGD score. Conclusion Different patterns of spontaneous neural activity in the cerebellum and putamen may underlie the neural substrate of PD motor subtypes. [ABSTRACT FROM AUTHOR]

The cell cycle is a temporal program that regulates DNA synthesis and cell division. When we compared the codon usage of cell cycle‐regulated genes with that of other genes, we discovered that there is a significant preference for non‐optimal codons. Moreover, genes encoding proteins that cycle at the protein level exhibit non‐optimal codon preferences. Remarkably, cell cycle‐regulated genes expressed in different phases display different codon preferences. Here, we show empirically that transfer RNA (tRNA) expression is indeed highest in the G2 phase of the cell cycle, consistent with the non‐optimal codon usage of genes expressed at this time, and lowest toward the end of G1, reflecting the optimal codon usage of G1 genes. Accordingly, protein levels of human glycyl‐, threonyl‐, and glutamyl‐prolyl tRNA synthetases were found to oscillate, peaking in G2/M phase. In light of our findings, we propose that non‐optimal (wobbly) matching codons influence protein synthesis during the cell cycle. We describe a new mathematical model that shows how codon usage can give rise to cell‐cycle regulation. In summary, our data indicate that cells exploit wobbling to generate cell cycle‐dependent dynamics of proteins. [ABSTRACT FROM AUTHOR]