In higher eukaryotes, transfer RNAs (tRNAs) with the same anticodon are encoded by multiple nuclear genes, and little is known about how mutations in these genes affect translation and cellular ...homeostasis. Similarly, the surveillance systems that respond to such defects in higher eukaryotes are not clear. Here, we discover that loss of GTPBP2, a novel binding partner of the ribosome recycling protein Pelota, in mice with a mutation in a tRNA gene that is specifically expressed in the central nervous system causes ribosome stalling and widespread neurodegeneration. Our results not only define GTPBP2 as a ribosome rescue factor but also unmask the disease potential of mutations in nuclear-encoded tRNA genes.
Aminoacyl-tRNA synthetases (aaRSs) are essential enzymes that catalyze the first reaction in protein biosynthesis, namely the charging of transfer RNAs (tRNAs) with their cognate amino acids. aaRSs ...have been increasingly implicated in dominantly and recessively inherited human diseases. The most common aaRS-associated monogenic disorder is the incurable neurodegenerative disease Charcot–Marie–Tooth neuropathy (CMT), caused by dominant mono-allelic mutations in aaRSs. With six currently known members (GlyRS, TyrRS, AlaRS, HisRS, TrpRS, and MetRS), aaRSs represent the largest protein family implicated in CMT etiology. After the initial discovery linking aaRSs to CMT, the field has progressed from understanding whether impaired tRNA charging is a critical component of this disease to elucidating the specific pathways affected by CMT-causing mutations in aaRSs. Although many aaRS CMT mutants result in loss of tRNA aminoacylation function, animal genetics studies demonstrated that dominant mutations in GlyRS cause CMT through toxic gain-of-function effects, which also may apply to other aaRS-linked CMT subtypes. The CMT-causing mechanism is likely to be multifactorial and involves multiple cellular compartments, including the nucleus and the extracellular space, where the normal WT enzymes also appear. Thus, the association of aaRSs with neuropathy is relevant to discoveries indicating that aaRSs also have nonenzymatic regulatory functions that coordinate protein synthesis with other biological processes. Through genetic, functional, and structural analyses, commonalities among different mutations and different aaRS-linked CMT subtypes have begun to emerge, providing insights into the nonenzymatic functions of aaRSs and the pathogenesis of aaRS-linked CMT to guide therapeutic development to treat this disease.
Although high-throughput RNA sequencing (RNA-seq) has greatly advanced small non-coding RNA (sncRNA) discovery, the currently widely used complementary DNA library construction protocol generates ...biased sequencing results. This is partially due to RNA modifications that interfere with adapter ligation and reverse transcription processes, which prevent the detection of sncRNAs bearing these modifications. Here, we present PANDORA-seq (panoramic RNA display by overcoming RNA modification aborted sequencing), employing a combinatorial enzymatic treatment to remove key RNA modifications that block adapter ligation and reverse transcription. PANDORA-seq identified abundant modified sncRNAs-mostly transfer RNA-derived small RNAs (tsRNAs) and ribosomal RNA-derived small RNAs (rsRNAs)-that were previously undetected, exhibiting tissue-specific expression across mouse brain, liver, spleen and sperm, as well as cell-specific expression across embryonic stem cells (ESCs) and HeLa cells. Using PANDORA-seq, we revealed unprecedented landscapes of microRNA, tsRNA and rsRNA dynamics during the generation of induced pluripotent stem cells. Importantly, tsRNAs and rsRNAs that are downregulated during somatic cell reprogramming impact cellular translation in ESCs, suggesting a role in lineage differentiation.
Over the course of evolution, eukaryotic aminoacyl-tRNA synthetases (aaRSs) progressively incorporated domains and motifs that have no essential connection to aminoacylation reactions. Their ...accretive addition to virtually all aaRSs correlates with the progressive evolution and complexity of eukaryotes. Based on recent experimental findings focused on a few of these additions and analysis of the aaRS proteome, we propose that they are markers for aaRS-associated functions beyond translation.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Combination chemotherapy refers to the use of multiple drugs to treat cancer. In this therapy, the optimal ratio of the drugs is essential to achieve drug synergism and the desired therapeutic ...effects. However, most delivery strategies are unable to precisely control the ratio of the drugs during the drug loading and delivery processes, resulting in inefficient synergy and unpredictable efficacy. Herein, a macrocyclic‐amphiphile‐based self‐assembled nanoparticle (MASN) that achieves precise loading and ratiometric delivery of therapeutic combinations is presented. By integrating multiple macrocyclic cavities within a single nanoparticle, the MASN can load multiple drug molecules via the host–guest interaction, and the ratio of the drugs loaded can be predicted with their initial concentrations and characteristic binding affinity. Moreover, MASNs are readily degraded under a hypoxic microenvironment, allowing spontaneous release of the drugs upon reaching tumor tissues. With precise drug loading and controlled release mechanisms, MASNs achieve ratiometric delivery of multiple commercial drugs to tumors, thereby achieving optimal anti‐tumor effects. Since the optimal drug ratio of a therapeutic combination can be quickly determined in vitro, MASNs can translate this optimal ratio to the therapeutic benefits in vivo, providing a potential platform for the rapid development of effective combination cancer therapies involving multiple drugs.
A macrocyclic‐amphiphile‐based self‐assembled nanoparticle (MASN) with the capability of precise loading and ratiometric delivery of different drugs is developed for effective combination chemotherapy. The MASN can quickly convert the optimal drug ratio of a therapeutic combination identified in vitro into therapeutic benefits in vivo, providing a potential platform for the rapid development of effective combinations of cancer therapies.
Hypoxia-induced angiogenesis maintains tissue oxygen supply and protects against ischemia but also enhances tumor progression and malignancy. This is mediated through activation of transcription ...factors like hypoxia-inducible factor 1 (HIF-1) and c-Myc, yet the impact of hypoxia on negative regulators of angiogenesis is unknown. During vascular development, seryl-tRNA synthetase (SerRS) regulates angiogenesis through a novel mechanism by counteracting c-Myc and transcriptionally repressing vascular endothelial growth factor A (VEGFA) expression. Here, we reveal that the transcriptional repressor role of SerRS is inactivated under hypoxia through phosphorylation by ataxia telangiectasia mutated (ATM) and ataxia telangiectasia mutated and RAD3-related (ATR) at Ser101 and Ser241 to attenuate its DNA binding capacity. In zebrafish, SerRSS101D/S241D, a phosphorylation-mimicry mutant, cannot suppress VEGFA expression to support normal vascular development. Moreover, expression of SerRSS101A/S241A, a phosphorylation-deficient and constitutively active mutant, prevents hypoxia-induced binding of c-Myc and HIF-1 to the VEGFA promoter, and activation of VEGFA expression. Consistently, SerRSS101A/S241A strongly inhibits normal and tumor-derived angiogenesis in mice. Therefore, we reveal a key step regulating hypoxic angiogenesis and highlight the importance of nuclear SerRS in post-developmental angiogenesis regulation in addition to vascular development. The role of nuclear SerRS in inhibiting both c-Myc and HIF-1 may provide therapeutic opportunities to correct dysregulation of angiogenesis in pathological settings.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Dominant mutations in glycyl-tRNA synthetase (GlyRS) cause a subtype of Charcot-Marie-Tooth neuropathy (CMT2D). Although previous studies have shown that GlyRS mutants aberrantly interact with Nrp1, ...giving insight into the disease's specific effects on motor neurons, these cannot explain length-dependent axonal degeneration. Here, we report that GlyRS mutants interact aberrantly with HDAC6 and stimulate its deacetylase activity on α-tubulin. A decrease in α-tubulin acetylation and deficits in axonal transport are observed in mice peripheral nerves prior to disease onset. An HDAC6 inhibitor used to restore α-tubulin acetylation rescues axonal transport deficits and improves motor functions of CMT2D mice. These results link the aberrant GlyRS-HDAC6 interaction to CMT2D pathology and suggest HDAC6 as an effective therapeutic target. Moreover, the HDAC6 interaction differs from Nrp1 interaction among GlyRS mutants and correlates with divergent clinical presentations, indicating the existence of multiple and different mechanisms in CMT2D.
Febrifugine is the active component of the Chinese herb Chang Shan (Dichroa febrifuga Lour.), which has been used for treating malaria-induced fever for about 2,000 years. Halofuginone (HF), the ...halogenated derivative of febrifugine, has been tested in clinical trials for potential therapeutic applications in cancer and fibrotic disease. Recently, HF was reported to inhibit T(H)17 cell differentiation by activating the amino acid response pathway, through inhibiting human prolyl-transfer RNA synthetase (ProRS) to cause intracellular accumulation of uncharged tRNA. Curiously, inhibition requires the presence of unhydrolysed ATP. Here we report an unusual 2.0 Å structure showing that ATP directly locks onto and orients two parts of HF onto human ProRS, so that one part of HF mimics bound proline and the other mimics the 3' end of bound tRNA. Thus, HF is a new type of ATP-dependent inhibitor that simultaneously occupies two different substrate binding sites on ProRS. Moreover, our structure indicates a possible similar mechanism of action for febrifugine in malaria treatment. Finally, the elucidation here of a two-site modular targeting activity of HF raises the possibility that substrate-directed capture of similar inhibitors might be a general mechanism that could be applied to other synthetases.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Objective
The study objective was to examine the association between phentermine/topiramate therapy and weight loss and adverse events in adults with overweight or obesity by meta‐analysis and ...systematic review.
Methods
Medical Subject Headings and free‐text terms were selected to search for eligible trials in PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), and Embase up to April 18, 2020. The quality of randomized controlled trials was evaluated by the Cochrane risk‐of‐bias tool. Meta‐analysis was performed using random‐effect models.
Results
Phentermine/topiramate therapy resulted in an average weight loss of 7.73 kg (95% CI: 6.60‐8.85) in general compared with placebo. The weight loss was related to the dose of phentermine/topiramate. Compared with placebo, the average weight loss was 3.55 kg (95% CI: 2.22‐4.88) for 3.75/23 mg, 7.27 kg (95% CI: 6.40‐8.13) for 7.5/46 mg, and 8.25 kg (95% CI: 6.92‐9.79) for 15/92 mg. For phentermine/topiramate participants in different weight‐loss subgroups, the weight loss of participants with ≥5%, ≥10%, and ≥15% baseline weight loss was 3.18 (95% CI: 2.75‐3.67), 5.32 (95% CI: 4.53‐6.25), and 5.65 (95% CI: 3.55‐9.01), respectively. Compared with placebo, the adverse events associated with the treatment mainly included dysgeusia (odds ratio OR = 8.86, 95% CI: 5.65‐13.89), paresthesia (OR = 8.51, 95% CI: 6.20‐11.67), dry mouth (OR = 6.71, 95% CI: 5.03‐8.94), disturbance in attention (OR = 4.48, 95% CI: 2.39‐8.41), irritability (OR = 4.10, 95% CI: 2.29‐7.33), hypoesthesia (OR = 3.81, 95% CI: 1.32‐11.00), constipation (OR = 2.43, 95% CI: 2.02‐2.93), and dizziness (OR = 2.26, 95% CI: 1.72‐2.98). Phentermine/topiramate also reduced waist circumference, blood pressure, blood sugar levels, and lipid levels.
Conclusions
Phentermine/topiramate has considerable benefit in reducing body weight, and the efficacy was closely related to the dosage. However, it increased the risk of nervous system‐related adverse events.
An epidemic of pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spreading worldwide. SARS-CoV-2 relies on its spike protein to invade host cells by interacting with ...the human receptor protein Angiotensin-Converting Enzymes 2 (ACE2). Therefore, designing an antibody or small-molecular entry blockers is of great significance for virus prevention and treatment. This study identified five potential small molecular anti-virus blockers via targeting SARS-CoV-2 spike protein by combining in silico technologies with in vitro experimental methods. The five molecules were natural products that binding to the RBD domain of SARS-CoV-2 was qualitatively and quantitively validated by both native Mass Spectrometry (MS) and Surface Plasmon Resonance (SPR). Anti-viral activity assays showed that the optimal molecule, H69C2, had a strong binding affinity (dissociation constant K
) of 0.0947 µM and anti-virus IC
of 85.75 µM.
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