The HIV-1 accessory protein Vif hijacks a cellular Cullin-RING ubiquitin ligase, CRL5, to promote degradation of the APOBEC3 (A3) family of restriction factors. Recently, the cellular transcription ...cofactor CBFβ was shown to form a complex with CRL5-Vif and to be essential for A3 degradation and viral infectivity. We now demonstrate that CBFβ is required for assembling a well-ordered CRL5-Vif complex by inhibiting Vif oligomerization and by activating CRL5-Vif via direct interaction. The CRL5-Vif-CBFβ holoenzyme forms a well-defined heterohexamer, indicating that Vif simultaneously hijacks CRL5 and CBFβ. Heterodimers of CBFβ and RUNX transcription factors contribute toward the regulation of genes, including those with immune system functions. We show that binding of Vif to CBFβ is mutually exclusive with RUNX heterodimerization and impacts the expression of genes whose regulatory domains are associated with RUNX1. Our results provide a mechanism by which a pathogen with limited coding capacity uses one factor to hijack multiple host pathways.
► Action of a viral-hijacked E3 requires binding to a cellular transcription cofactor ► E3 assembly prevents binding of the transcription cofactor to regulatory partners ► A viral protein can interfere with multiple cellular pathways by these mechanisms
Cellular restriction factors help to defend humans against human immunodeficiency virus (HIV). HIV accessory proteins hijack at least three different Cullin-RING ubiquitin ligases, which must be ...activated by the small ubiquitin-like protein NEDD8, in order to counteract host cellular restriction factors. We found that conjugation of NEDD8 to Cullin-5 by the NEDD8-conjugating enzyme UBE2F is required for HIV Vif-mediated degradation of the host restriction factor APOBEC3G (A3G). Pharmacological inhibition of the NEDD8 E1 by MLN4924 or knockdown of either UBE2F or its RING-protein binding partner RBX2 bypasses the effect of Vif, restoring the restriction of HIV by A3G. NMR mapping and mutational analyses define specificity determinants of the UBE2F NEDD8 cascade. These studies demonstrate that disrupting host NEDD8 cascades presents a novel antiretroviral therapeutic approach enhancing the ability of the immune system to combat HIV.
Liquid biopsy approaches are relatively well developed for cancer therapy monitoring and disease relapse, but they also have incredible potential in the cancer early detection and screening field. ...There are, however, several challenges to overcome before this potential can be met. Research in this area needs to be cohesive and, as a driver of research, Cancer Research UK is in an ideal position to enable this.
The HIV-1 protein Rev controls a critical step in viral replication by mediating the nuclear export of unspliced and singly-spliced viral mRNAs. Multiple Rev subunits assemble on the Rev Response ...Element (RRE), a structured region present in these RNAs, and direct their export through the Crm1 pathway. Rev-RRE assembly occurs via several Rev oligomerization and RNA-binding steps, but how these steps are coordinated to form an export-competent complex is unclear. Here, we report the first crystal structure of a Rev dimer-RRE complex, revealing a dramatic rearrangement of the Rev-dimer upon RRE binding through re-packing of its hydrophobic protein-protein interface. Rev-RNA recognition relies on sequence-specific contacts at the well-characterized IIB site and local RNA architecture at the second site. The structure supports a model in which the RRE utilizes the inherent plasticity of Rev subunit interfaces to guide the formation of a functional complex.
The Cullin-RING E3 ligase (CRL) family is commonly hijacked by pathogens to redirect the host ubiquitin proteasome machinery to specific targets. During HIV infection, CRL5 is hijacked by HIV Vif to ...target viral restriction factors of the APOBEC3 family for ubiquitination and degradation. Here, using a quantitative proteomics approach, we identify the E3 ligase ARIH2 as a regulator of CRL5-mediated APOBEC3 degradation. The CUL5Vif/CBFß complex recruits ARIH2 where it acts to transfer ubiquitin directly to the APOBEC3 targets. ARIH2 is essential for CRL5-dependent HIV infectivity in primary CD4+ T cells. Furthermore, we show that ARIH2 cooperates with CRL5 to prime other cellular substrates for polyubiquitination, suggesting this may represent a general mechanism beyond HIV infection and APOBEC3 degradation. Taken together, these data identify ARIH2 as a co-factor in the Vif-hijacked CRL5 complex that contributes to HIV infectivity and demonstrate the operation of the E1-E2-E3/E3-substrate ubiquitination mechanism in a viral infection context.
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•Quantitative proteomics identifies the E3 ligase ARIH2 as part of CRL5Vif/CBFß complex•CUL5Vif/CBFß complex recruits ARIH2 to transfer ubiquitin directly to APOBEC3 proteins•ARIH2 acts in an E1-E2-E3/E3 cascade to target degradation of APOBEC3 restriction factors•ARIH2 is essential for efficient HIV infection in primary CD4+ T cells
Degradation of APOBEC3 proteins by HIV Vif hijacking Cullin RING E3 ligase 5 is essential for HIV proliferation. Hüttenhain et al. discovered the host factor ARIH2, which works with CUL5Vif/CBFß via a tag-team mechanism to target APOBEC3 proteins for ubiquitination and is essential for HIV proliferation in primary CD4+ T cells.
We have developed a platform for quantitative genetic interaction mapping using viral infectivity as a functional readout and constructed a viral host-dependency epistasis map (vE-MAP) of 356 human ...genes linked to HIV function, comprising >63,000 pairwise genetic perturbations. The vE-MAP provides an expansive view of the genetic dependencies underlying HIV infection and can be used to identify drug targets and study viral mutations. We found that the RNA deadenylase complex, CNOT, is a central player in the vE-MAP and show that knockout of CNOT1, 10, and 11 suppressed HIV infection in primary T cells by upregulating innate immunity pathways. This phenotype was rescued by deletion of IRF7, a transcription factor regulating interferon-stimulated genes, revealing a previously unrecognized host signaling pathway involved in HIV infection. The vE-MAP represents a generic platform that can be used to study the global effects of how different pathogens hijack and rewire the host during infection.
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•We adapted the E-MAP approach to study genetic interactions underlying viral infection•We studied host gene pairs as well as gene-drug and gene-viral mutant combinations•The HIV vE-MAP highlighted a role for the CNOT complex in mediating infection•CNOT mediates HIV infection in primary CD4+ T cells by suppression of innate immunity
Most experimental genetic screens studying pathogen infection study one genetic element at a time; however, Gordon et al. adapted epistasis mapping to study combinations of perturbations impacting HIV infection and use their approach to identify and characterize a role for CCR4-NOT in mediating HIV infection.
Introduction
A recent meta‐analysis has suggested that routine measurement of the cervical length should be performed in conjunction with the anomaly scan to identify a group of women at increased ...risk of preterm delivery. We decided to investigate whether this recommendation is justifiable in a population where the risk of preterm birth is low.
Material and methods
We reviewed 12 years of obstetric data from the Coombe Women and Infants University Hospital. Relative risks of adverse outcomes from the randomized controlled trial were applied and we extrapolated the possible numbers of women requiring intervention. We then used published neonatal data to estimate the cost of neonatal care and estimated the costs of providing the service.
Results
Over 12 years from 2000 until 2011, there were 94 646 singleton deliveries, 1776 happening before 34 weeks. Spontaneous onset occurred in 882 (49.7%) of this group. These 882 births were studied. If we apply the figures from a randomized controlled trial, 1609 women (1.7% from our total population) would be expected to have a cervical length 15 mm. If we gave vaginal progesterone to all women with a sonographically short cervix, we would reduce the delivery rate before 34 weeks by 27.7%. The annual costs of providing the service were estimated to be €109 249 and the cost of immediate neonatal care was estimated to be €380 514.
Conclusion
Given the implications associated with preterm delivery, routine measurement of cervical length at the time of the anomaly scan may be justifiable from a cost point of view in a population where the risk of preterm birth is low.
It has been proposed that the Robson Ten-Group Classification System be used as a global standard for assessing, monitoring and comparing cesarean delivery (CD) rates within and between maternity ...services. Our objective was to compare the change of CD rates within the 10-Group Classification System in our institution over 10 years.
From 2005–2014 inclusive data was collected prospectively and all women were classified using the obstetric concepts and parameters described in the Ten-Group Classification System. Linear regression and weighted Least Squares regression analyses were used to analyze trends over time.
During 2005–2014 inclusive, 88,004 mothers delivered 89,649 babies ≥500 g. Over the 10 year period there was an increase in CD rate from 18.3% to 23.5%, with a linear increase in CD rate by 0.6% annually (95% CI:0.52, 0.75;p < 0.001). The main contribution to the increase in the CD rate was Group 2a (induced single cephalic nulliparous women at term), Group 2b (pre-labor single cephalic nulliparous women at term) and Group 5 (single cephalic multiparous women at term with a previous CD). No increase in CD rate was noted in Group 1 (single cephalic nulliparous women presenting in spontaneous labor at term). The percentage of women ≥35 years of age increased from 28.4% to 39.8% over the study period (0.98% per year; 95% CI:0.64, 1.33;p < 0.001).
The driving force for the increase in CD in the National Maternity Hospital has been induction of labor and pre-labor CD in nulliparous women with a single cephalic pregnancy at term. This inevitably results in a larger population of women with a previous CD and therefore a secondary contribution to the increase in the overall CD rate.
Amniocentesis for genetic diagnosis is most commonly done between 15 and 22 weeks of gestation, but can be performed at later gestational ages. The safety and genetic diagnostic accuracy of ...amniocentesis have been well-established through numerous large-scale, multicenter studies for procedures before 24 weeks, but comprehensive data on late amniocentesis remain sparse.
To evaluate the indications, diagnostic yield, safety, and maternal and fetal outcomes associated with amniocentesis performed at or beyond 24 weeks of gestation.
We conducted an international, multicenter retrospective cohort study examining pregnant individuals who underwent amniocentesis for prenatal diagnostic testing at gestational ages between 24w0d and 36w6d. The study, spanning from 2011 to 2022, involved nine referral centers. We included singleton or twin pregnancies with documented outcomes, excluding cases where other invasive procedures were performed during pregnancy or if amniocentesis was conducted for obstetric indications. We analyzed indications for late amniocentesis, types of genetic tests performed, their results, and the diagnostic yield, along with pregnancy outcomes and post-procedure complications.
Of the 752 pregnant individuals included in our study, late amniocentesis was primarily performed for the prenatal diagnosis of structural anomalies (91.6%), followed by suspected fetal infection (2.3%) and high-risk findings from cell-free DNA screening (1.9%). The median gestational age at the time of the procedure was 28w5d, and 98.3% of pregnant individuals received results of genetic testing before birth or pregnancy termination. The diagnostic yield was 22.9%, and a diagnosis was made 2.4 times more often for fetuses with anomalies in multiple organ systems (36.4%) compared to those with anomalies in a single organ system (15.3%). Additionally, the diagnostic yield varied depending on the specific organ system involved, with the highest yield for musculoskeletal anomalies (36.7%) and hydrops fetalis (36.4%) when a single organ system or entity was affected. The most prevalent genetic diagnoses were aneuploidies (46.8%), followed by copy number variants (26.3%) and monogenic disorders (22.2%). The median gestational age at delivery was 38w3d, with an average of 59 days between the procedure and delivery date. The overall complication rate within two weeks post-procedure was 1.2%. We found no significant difference in the rate of preterm delivery between pregnant individuals undergoing amniocentesis between 24-28 weeks and those between 28-32 weeks, reinforcing the procedure's safety across these gestational periods.
Late amniocentesis, at or after 24 weeks gestation, especially for pregnancies complicated by multiple congenital anomalies, has a high diagnostic yield and a low complication rate, underscoring its clinical utility. It provides pregnant individuals and their providers with a comprehensive diagnostic evaluation and results before delivery, enabling informed counseling and optimized perinatal and neonatal care planning.
Overlapping genes pose an evolutionary dilemma as one DNA sequence evolves under the selection pressures of multiple proteins. Here, we perform systematic statistical and mutational analyses of the ...overlapping HIV-1 genes tat and rev and engineer exhaustive libraries of non-overlapped viruses to perform deep mutational scanning of each gene independently. We find a “segregated” organization in which overlapped sites encode functional residues of one gene or the other, but never both. Furthermore, this organization eliminates unfit genotypes, providing a fitness advantage to the population. Our comprehensive analysis reveals the extraordinary manner in which HIV minimizes the constraint of overlapping genes and repurposes that constraint to its own advantage. Thus, overlaps are not just consequences of evolutionary constraints, but rather can provide population fitness advantages.
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•Overlapped regions in HIV-1 are not more conserved than non-overlapped regions•Tat and Rev segregate motifs: functional regions overlap non-functional regions•When not overlapped, non-functional regions vary even more•Tat constrains Rev, increasing the fitness of the viral genotypic landscape
In HIV, a fitness advantage is conferred to the population by the constraints placed on overlapping genes.
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