Viral proteins make extensive use of short peptide interaction motifs to hijack cellular host factors. However, most current large-scale methods do not identify this important class of ...protein-protein interactions. Uncovering peptide mediated interactions provides both a molecular understanding of viral interactions with their host and the foundation for developing novel antiviral reagents. Here we describe a viral peptide discovery approach covering 23 coronavirus strains that provides high resolution information on direct virus-host interactions. We identify 269 peptide-based interactions for 18 coronaviruses including a specific interaction between the human G3BP1/2 proteins and an ΦxFG peptide motif in the SARS-CoV-2 nucleocapsid (N) protein. This interaction supports viral replication and through its ΦxFG motif N rewires the G3BP1/2 interactome to disrupt stress granules. A peptide-based inhibitor disrupting the G3BP1/2-N interaction dampened SARS-CoV-2 infection showing that our results can be directly translated into novel specific antiviral reagents.
Viruses interact with numerous host factors to facilitate viral replication and to dampen antiviral defense mechanisms. We currently have a limited mechanistic understanding of how SARS-CoV-2 binds ...host factors and the functional role of these interactions. Here, we uncover a novel interaction between the viral NSP3 protein and the fragile X mental retardation proteins (FMRPs: FMR1, FXR1-2). SARS-CoV-2 NSP3 mutant viruses preventing FMRP binding have attenuated replication in vitro and reduced levels of viral antigen in lungs during the early stages of infection. We show that a unique peptide motif in NSP3 binds directly to the two central KH domains of FMRPs and that this interaction is disrupted by the I304N mutation found in a patient with fragile X syndrome. NSP3 binding to FMRPs disrupts their interaction with the stress granule component UBAP2L through direct competition with a peptide motif in UBAP2L to prevent FMRP incorporation into stress granules. Collectively, our results provide novel insight into how SARS-CoV-2 hijacks host cell proteins and provides molecular insight into the possible underlying molecular defects in fragile X syndrome.
Synopsis
The SARS-CoV-2 NSP3 protein binds directly to fragile X mental retardation proteins (FMRPs) to support viral replication. NSP3 binding disrupts FMRP interaction with the stress granule protein UBAP2L, thereby preventing FMRP localization to these structures.
The SARS-CoV-2 NSP3 protein binds to the KH domains of FMRPs through a short peptide motif.
Engineered SARS-CoV-2 viruses unable to bind FMRPs have reduced replication.
NSP3 binding to FMRPs disrupts their localization to stress granules through competition with UBAP2L.
The SARS-CoV-2 NSP3 protein binds directly to fragile X mental retardation proteins (FMRPs) to support viral replication. NSP3 binding disrupts FMRP interaction with the stress granule protein UBAP2L, thereby preventing FMRP localization to these structures.
The transcription factor runt-related transcription factor 1 (Runx1) is essential for the establishment of definitive hematopoiesis during embryonic development. In adult blood homeostasis, Runx1 ...plays a pivotal role in the maturation of lymphocytes and megakaryocytes. Furthermore, Runx1 is required for the regulation of hematopoietic stem and progenitor cells. However, how Runx1 orchestrates self-renewal and lineage choices in combination with other factors is not well understood. In the present study, we describe a genome-scale RNA interference screen to detect genes that cooperate with Runx1 in regulating hematopoietic stem and progenitor cells. We identify the polycomb group protein Pcgf1 as an epigenetic regulator involved in hematopoietic cell differentiation and show that simultaneous depletion of Runx1 and Pcgf1 allows sustained self-renewal while blocking differentiation of lineage marker–negative cells in vitro. We found an up-regulation of HoxA cluster genes on Pcgf1 knock-down that possibly accounts for the increase in self-renewal. Moreover, our data suggest that cells lacking both Runx1 and Pcgf1 are blocked at an early progenitor stage, indicating that a concerted action of the transcription factor Runx1, together with the epigenetic repressor Pcgf1, is necessary for terminal differentiation. The results of the present study uncover a link between transcriptional and epigenetic regulation that is required for hematopoietic differentiation.
Objectives: Abnormalities in norepinephrine (NE) and serotonin (5‐HT) are implicated in bipolar disorder (BD). We examined 5‐HT input and NE neurons in the locus coeruleus (LC, the NE nucleus that ...innervates the forebrain) in BD by quantifying immunoreactivity (IR) for tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH), the biosynthetic enzymes for NE and 5‐HT, respectively.
Methods: Six suicides with BD were compared to matched normal controls and unipolar major depression suicides, using immunocytochemistry with computer‐assisted quantification of immunoreactivity.
Results: Depressed bipolar suicides had 26.7 ± 1.3% of LC area occupied by the TH immunoreactive (TH‐IR) process, while controls had 50.7 ± 8% (p = 0.002) and unipolar depressed suicides had 50.3 ± 2.5% (p = 0.003). In bipolars, these processes did not stain as darkly (1.9 ± 0.5 × background) as controls (2.9 ± 0.9 × background; p = 0.01) or unipolars (2.9 ± 0.6 × background; p = 0.002). Bipolar suicides also had less TPH‐IR processes in the LC (11.7 ± 10%) compared with controls (32.8 ± 8.8%; p = 0.01) or unipolar suicides (30.3 ± 8%; p = 0.02). The TPH‐IR intensity did not differ between groups.
Conclusions: We found less TH‐IR and TPH‐IR in the LC in depressed bipolar suicides, but not unipolar suicides, suggesting that both NE and 5‐HT activity is lower in BD. Studies during manic or euthymic states will determine whether these changes are mood state dependent.
Respiratory syncytial virus (RSV) has been identified as an important cause of lower respiratory tract disease in infants. In patients at high risk, prevention is attempted through immunoprophylaxis ...with palivizumab. In 2008, as a result of revisions to the American Academy of Pediatrics' guidelines, South Carolina Medicaid reduced the number of approved palivizumab doses from six to five. This study attempted to determine whether the reduction of approved doses would affect hospitalization and emergency department visits and to characterize dose administration.
We obtained data for all South Carolina Medicaid reimbursed births from November 2004 through March 2009. For each RSV season, infants who should have received palivizumab were identified. Rates of outpatient palivizumab dosing and hospitalizations and emergency department visits because of RSV also were identified.
In the seasons sampled, 1956 infants met eligibility criteria for our study. Infants younger than 29 weeks' gestation received 34% to 48% of their total eligible palivizumab doses, whereas infants 29 to 31 weeks' gestation received 36% to 46% of their doses. The rate of emergency department visits and inpatient admissions because of RSV did not differ significantly across years.
In evaluating our primary outcome, there was no increase in hospitalizations or emergency department visits. Overall, we did note a poor dosing rate in all of the groups. A statistically significant decline in dosing per eligible month was noted following the dose reductions. Despite solid evidence of the benefits of palivizumab in high-risk groups, we are doing an inadequate job of dosing these patients.
We believe adherence to current recommendations for palivizumab dosing is suboptimal in preterm infants insured by the South Carolina Medicaid program. Healthcare professionals must work harder to identify and follow-up with patients who qualify for palivizumab dosing, including infants who meet criteria for a second season.
Aim
The aim of the present study was to explore the impact of strategies to reduce polypharmacy on mortality, hospitalization and change in number of drugs.
Methods
Systematic review and ...meta‐analysis: a systematic literature search targeting patients ≥65 years with polypharmacy (≥4 drugs), focusing on patient‐relevant outcome measures, was conducted. We included controlled studies aiming to reduce polypharmacy. Two reviewers independently assessed studies for eligibility, extracted data and evaluated study quality.
Results
Twenty‐five studies, including 10 980 participants, were included, comprising 21 randomized controlled trials and four nonrandomized controlled trials. The majority of the included studies aimed at improving quality or the appropriateness of prescribing by eliminating inappropriate and non‐evidence‐based drugs. These strategies to reduce polypharmacy had no effect on all‐cause mortality (odds ratio 1.02; 95% confidence interval 0.84, 1.23). Only single studies found improvements, in terms of reducing the number of hospital admissions, in favour of the intervention group. At baseline, patients were taking, on average, 7.4 drugs in both the intervention and the control groups. At follow‐up, the weighted mean number of drugs was reduced (−0.2) in the intervention group but increased (+0.2) in controls.
Conclusions
There is no convincing evidence that the strategies assessed in the present review are effective in reducing polypharmacy or have an impact on clinically relevant endpoints. Interventions are complex; it is still unclear how best to organize and implement them to achieve a reduction in inappropriate polypharmacy. There is therefore a need to develop more effective strategies to reduce inappropriate polypharmacy and to test them in large, pragmatic randomized controlled trials on effectiveness and feasibility.
Cardiac macrophages are crucial for tissue repair after cardiac injury but are not well characterized. Here we identify four populations of cardiac macrophages. At steady state, resident macrophages ...were primarily maintained through local proliferation. However, after macrophage depletion or during cardiac inflammation, Ly6chi monocytes contributed to all four macrophage populations, whereas resident macrophages also expanded numerically through proliferation. Genetic fate mapping revealed that yolk-sac and fetal monocyte progenitors gave rise to the majority of cardiac macrophages, and the heart was among a minority of organs in which substantial numbers of yolk-sac macrophages persisted in adulthood. CCR2 expression and dependence distinguished cardiac macrophages of adult monocyte versus embryonic origin. Transcriptional and functional data revealed that monocyte-derived macrophages coordinate cardiac inflammation, while playing redundant but lesser roles in antigen sampling and efferocytosis. These data highlight the presence of multiple cardiac macrophage subsets, with different functions, origins, and strategies to regulate compartment size.
•Yolk-sac and fetal monocyte progenitors give rise to adult cardiac macrophages•Yolk-sac macrophages persisted into adulthood only in the heart, liver, and brain•Embryonically established resident macrophages can be replaced by blood monocytes•Cardiac macrophages differentially activate T cells and take up dying cardiomyocytes
A key resistance mechanism to platinum-based chemotherapies and PARP inhibitors in
-mutant cancers is the acquisition of
reversion mutations that restore protein function. To estimate the prevalence ...of
reversion mutations in high-grade ovarian carcinoma (HGOC), we performed targeted next-generation sequencing of circulating cell-free DNA (cfDNA) extracted from pretreatment and postprogression plasma in patients with deleterious germline or somatic
mutations treated with the PARP inhibitor rucaparib.
reversion mutations were identified in pretreatment cfDNA from 18% (2/11) of platinum-refractory and 13% (5/38) of platinum-resistant cancers, compared with 2% (1/48) of platinum-sensitive cancers (
= 0.049). Patients without
reversion mutations detected in pretreatment cfDNA had significantly longer rucaparib progression-free survival than those with reversion mutations (median, 9.0 vs. 1.8 months; HR, 0.12;
< 0.0001). To study acquired resistance, we sequenced 78 postprogression cfDNA, identifying eight additional patients with
reversion mutations not found in pretreatment cfDNA. SIGNIFICANCE:
reversion mutations are detected in cfDNA from platinum-resistant or platinum-refractory HGOC and are associated with decreased clinical benefit from rucaparib treatment. Sequencing of cfDNA can detect multiple
reversion mutations, highlighting the ability to capture multiclonal heterogeneity.
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