Identification of novel integrin binding partners for CIB1: structural and thermodynamic basis of CIB1 promiscuity

The short cytoplasmic tails of the α and β chains of integrin adhesion receptors regulate integrin activation and cell signaling. Significantly less is known about proteins that bind to α-integrin cytoplasmic tails (CTs) than β-CTs to regulate integrins. CIB1 was previously identified as an αIIb binding partner that inhibits agonist-induced activation of the platelet-specific integrin, αIIbβ3. A sequence alignment of all α-integrin CTs revealed that key residues in the CIB1 binding site on αIIb are well-conserved, and was used to delineate a consensus binding site (I/L-x-x-x-L/M-W/Y-K-x-G-F-F). Because the CIB1 binding site on αIIb is conserved in all α-integrins, and CIB1 expression is ubiquitous, we asked if CIB1 could interact with other α-integrin CTs. We predicted that multiple α-integrin CTs were capable of binding to the same hydrophobic binding pocket on CIB1 with docking models generated by all-atom replica exchange discrete molecular dynamics. After demonstrating novel in vivo interactions between CIB1 and other whole integrin complexes with co-immunopreceipitations, we validated the modeled predictions with solid-phase competitive binding assays showing that other α-integrin CTs compete with the αIIb CT for binding to CIB1 in vitro. Isothermal titration calorimetry measurements indicated that this binding is driven by hydrophobic interactions and depends on residues in the CIB1 consensus binding site. These new mechanistic details of CIB1-integrin binding imply that CIB1 could bind to all integrin complexes and act as a broad regulator of integrin function

Efficacy of Losartan in Hospitalized Patients With COVID-19-Induced Lung Injury: A Randomized Clinical Trial

Importance: SARS-CoV-2 viral entry may disrupt angiotensin II (AII) homeostasis, contributing to COVID-19 induced lung injury. AII type 1 receptor blockade mitigates lung injury in preclinical models, although data in humans with COVID-19 remain mixed. Objective: To test the efficacy of losartan to reduce lung injury in hospitalized patients with COVID-19. Design, Setting, and Participants: This blinded, placebo-controlled randomized clinical trial was conducted in 13 hospitals in the United States from April 2020 to February 2021. Hospitalized patients with COVID-19 and a respiratory sequential organ failure assessment score of at least 1 and not already using a renin-angiotensin-aldosterone system (RAAS) inhibitor were eligible for participation. Data were analyzed from April 19 to August 24, 2021. Interventions: Losartan 50 mg orally twice daily vs equivalent placebo for 10 days or until hospital discharge. Main Outcomes and Measures: The primary outcome was the imputed arterial partial pressure of oxygen to fraction of inspired oxygen (Pao2:Fio2) ratio at 7 days. Secondary outcomes included ordinal COVID-19 severity; days without supplemental o2, ventilation, or vasopressors; and mortality. Losartan pharmacokinetics and RAAS components (AII, angiotensin-[1-7] and angiotensin-converting enzymes 1 and 2)] were measured in a subgroup of participants. Results: A total of 205 participants (mean [SD] age, 55.2 [15.7] years; 123 [60.0%] men) were randomized, with 101 participants assigned to losartan and 104 participants assigned to placebo. Compared with placebo, losartan did not significantly affect Pao2:Fio2 ratio at 7 days (difference, -24.8 [95%, -55.6 to 6.1]; P = .12). Compared with placebo, losartan did not improve any secondary clinical outcomes and led to fewer vasopressor-free days than placebo (median [IQR], 9.4 [9.1-9.8] vasopressor-free days vs 8.7 [8.2-9.3] vasopressor-free days). Conclusions and Relevance: This randomized clinical trial found that initiation of orally administered losartan to hospitalized patients with COVID-19 and acute lung injury did not improve Pao2:Fio2 ratio at 7 days. These data may have implications for ongoing clinical trials. Trial Registration: ClinicalTrials.gov Identifier: NCT04312009

CIB1 depletion impairs cell survival and tumor growth in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is an aggressive breast cancer subtype with generally poor prognosis and no available targeted therapies, highlighting a critical unmet need to identify and characterize novel therapeutic targets. We previously demonstrated that CIB1 is necessary for cancer cell survival and proliferation via regulation of two oncogenic signaling pathways, RAF–MEK–ERK and PI3K–AKT. Because these pathways are often upregulated in TNBC, we hypothesized that CIB1 may play a broader role in TNBC cell survival and tumor growth. Methods utilized include inducible RNAi depletion of CIB1 in vitro and in vivo, immunoblotting, clonogenic assay, flow cytometry, RNA-sequencing, bioinformatics analysis, and Kaplan–Meier survival analysis. CIB1 depletion resulted in significant cell death in 8 of 11 TNBC cell lines tested. Analysis of components related to PI3K–AKT and RAF–MEK–ERK signaling revealed that elevated AKT activation status and low PTEN expression were key predictors of sensitivity to CIB1 depletion. Furthermore, CIB1 knockdown caused dramatic shrinkage of MDA-MB-468 xenograft tumors in vivo. RNA sequence analysis also showed that CIB1 depletion in TNBC cells activates gene programs associated with decreased proliferation and increased cell death. CIB1 expression levels per se did not predict TNBC susceptibility to CIB1 depletion, and CIB1 mRNA expression levels did not associate with TNBC patient survival. Our data are consistent with the emerging theory of non-oncogene addiction, where a large subset of TNBCs depend on CIB1 for cell survival and tumor growth, independent of CIB1 expression levels. Our data establish CIB1 as a novel therapeutic target for TNBC

Chemoproteomic Discovery of AADACL1 as a Regulator of Human Platelet Activation

A comprehensive knowledge of the platelet proteome is necessary for understanding thrombosis and for conceiving novel antiplatelet therapies. To discover new biochemical pathways in human platelets, we screened platelets with a carbamate library designed to interrogate the serine hydrolase subproteome and used competitive activity-based protein profiling to map the targets of active carbamates. We identified an inhibitor that targets arylacetamide deacetylase-like 1 (AADACL1), a lipid deacetylase originally identified in invasive cancers. Using this compound, along with highly selective second-generation inhibitors of AADACL1, metabolomics and RNA interference, we show that AADACL1 regulates platelet aggregation, thrombus growth, RAP1 and PKC activation, lipid metabolism and fibrinogen binding to platelets and megakaryocytes. These data provide the first evidence that AADACL1 regulates platelet and megakaryocyte activation and highlight the value of this chemoproteomic strategy for target discovery in platelets

Mobilization of genomic islands of Staphylococcus aureus by temperate bacteriophage

The virulence of Staphylococcus aureus, in both human and animal hosts, is largely influenced by the acquisition of mobile genetic elements (MGEs). Most S. aureus strains carry a variety of MGEs, including three genomic islands (νSaα, νSaβ, νSaγ) that are diverse in virulence gene content but conserved within strain lineages. Although the mobilization of pathogenicity islands, phages and plasmids has been well studied, the mobilization of genomic islands is poorly understood. We previously demonstrated the mobilization of νSaβ by the adjacent temperate bacteriophage ϕSaBov from strain RF122. In this study, we demonstrate that ϕSaBov mediates the mobilization of νSaα and νSaγ, which are located remotely from ϕSaBov, mostly to recipient strains belonging to ST151. Phage DNA sequence analysis revealed that chromosomal DNA excision events from RF122 were highly specific to MGEs, suggesting sequence-specific DNA excision and packaging events rather than generalized transduction by a temperate phage. Disruption of the int gene in ϕSaBov did not affect phage DNA excision, packaging, and integration events. However, disruption of the terL gene completely abolished phage DNA packing events, suggesting that the primary function of temperate phage in the transfer of genomic islands is to allow for phage DNA packaging by TerL and that transducing phage particles are the actual vehicle for transfer. These results extend our understanding of the important role of bacteriophage in the horizontal transfer and evolution of genomic islands in S. aureus

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Prevention of mother-to-child transmission of HIV in Zambia: implementing efficacious ARV regimens in primary health centers

<p>Abstract</p> <p>Background</p> <p>Safety and effectiveness of efficacious antiretroviral (ARV) regimens beyond single-dose nevirapine (sdNVP) for prevention of mother-to-child transmission (PMTCT) have been demonstrated in well-controlled clinical studies or in secondary- and tertiary-level facilities in developing countries. This paper reports on implementation of and factors associated with efficacious ARV regimens among HIV-positive pregnant women attending antenatal clinics in primary health centers (PHCs) in Zambia.</p> <p>Methods</p> <p>Blood sample taken for CD4 cell count, availability of CD4 count results, type of ARV prophylaxis for mothers, and additional PMTCT service data were collected for HIV-positive pregnant women and newborns who attended 60 PHCs between April 2007 and March 2008.</p> <p>Results</p> <p>Of 14,815 HIV-positive pregnant women registered in the 60 PHCs, 2,528 (17.1%) had their CD4 cells counted; of those, 1,680 (66.5%) had CD4 count results available at PHCs; of those, 796 (47.4%) had CD4 count ≤ 350 cells/mm³and thus were eligible for combination antiretroviral treatment (cART); and of those, 581 (73.0%) were initiated on cART. The proportion of HIV-positive pregnant women whose blood sample was collected for CD4 cell count was positively associated with (1) blood-draw for CD4 count occurring on the same day as determination of HIV-positive status; (2) CD4 results sent back to the health facilities within seven days; (3) facilities <it>without </it>providers trained to offer ART; and (4) urban location of PHC. Initiation of cART among HIV-positive pregnant women was associated with the PHC's capacity to provide care and antiretroviral treatment services. Overall, of the 14,815 HIV-positive pregnant women registered, 10,015 were initiated on any type of ARV regimen: 581 on cART, 3,041 on short course double ARV regimen, and 6,393 on sdNVP.</p> <p>Conclusion</p> <p>Efficacious ARV regimens beyond sdNVP can be implemented in resource-constrained PHCs. The majority (73.0%) of women identified eligible for ART were initiated on cART; however, a minority (11.3%) of HIV-positive pregnant women were assessed for CD4 count and had their test results available. Factors associated with implementation of more efficacious ARV regimens include timing of blood-draw for CD4 count and capacity to initiate cART onsite where PMTCT services were being offered.</p

Genes, Education, and Labor Market Outcomes: Evidence from the Health and Retirement Study

Recent advances have led to the discovery of specific genetic variants that predict educational attainment. We study how these variants, summarized as a genetic score variable, are associated with human capital accumulation and labor market outcomes in the Health and Retirement Study (HRS). We demonstrate that the same genetic score that predicts education is also associated with higher wages, but only among individuals with a college education. Moreover, the genetic gradient in wages has grown in more recent birth cohorts, consistent with interactions between technological change and labor market ability. We also show that individuals who grew up in economically disadvantaged households are less likely to go to college when compared to individuals with the same genetic score, but from higher socioeconomic status households. Our findings provide support for the idea that childhood socioeconomic status is an important moderator of the economic returns to genetic endowments. Moreover, the finding that childhood poverty limits the educational attainment of high-ability individuals suggests the existence of unrealized human potential