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The thymus is essential for establishing adaptive immunity yet undergoes age-related involution that leads to compromised immune responsiveness. The thymus is also extremely sensitive to acute insult and although capable of regeneration, this capacity declines with age for unknown reasons. We applied single-cell and spatial transcriptomics, lineage-tracing and advanced imaging to define age-related changes in nonhematopoietic stromal cells and discovered the emergence of two atypical thymic epithelial cell (TEC) states. These age-associated TECs (aaTECs) formed high-density peri-medullary epithelial clusters that were devoid of thymocytes; an accretion of nonproductive thymic tissue that worsened with age, exhibited features of epithelial-to-mesenchymal transition and was associated with downregulation of FOXN1. Interaction analysis revealed that the emergence of aaTECs drew tonic signals from other functional TEC populations at baseline acting as a sink for TEC growth factors. Following acute injury, aaTECs expanded substantially, further perturbing trophic regeneration pathways and correlating with defective repair of the involuted thymus. These findings therefore define a unique feature of thymic involution linked to immune aging and could have implications for developing immune-boosting therapies in older individuals.
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Developing vaccines that promote CD8 + T cell memory is a challenge for infectious disease and cancer immunotherapy. TCF-1 + stem cell-like memory T (T SCM ) cells are important determinants of long-lived memory. Yet, the developmental requirements for T SCM formation are unclear. Here, we identify the temporal window for type I interferon (IFN-I) receptor (IFNAR) blockade to drive T SCM cell generation. T SCM cells were transcriptionally distinct and emerged from a transitional precursor of exhausted (T PEX ) cellular state concomitant with viral clearance. T SCM differentiation correlated with T cell retention within the lymph node paracortex, due to increased CXCR3 chemokine abundance which disrupted gradient formation. These affects were due a counterintuitive increase in IFNψ, which controlled cell location. Combining IFNAR inhibition with mRNA-LNP vaccination promoted specific T SCM differentiation and enhanced protection against chronic infection. These finding propose a new approach to vaccine design whereby modulation of inflammation promotes memory formation and function. HIGHLIGHTS: Early, transient inhibition of the type I interferon (IFN) receptor (IFNAR) during acute viral infection promotes stem cell-like memory T (T SCM ) cell differentiation without establishing chronic infection. T SCM and precursor of exhausted (T PEX ) cellular states are distinguished transcriptionally and by cell surface markers. Developmentally, T SCM cell differentiation occurs via a transition from a T PEX state coinciding with viral clearance. Transient IFNAR blockade increases IFNψ production to modulate the ligands of CXCR3 and couple T SCM differentiation to cell retention within the T cell paracortex of the lymph node. Specific promotion of T SCM cell differentiation with nucleoside-modified mRNA-LNP vaccination elicits enhanced protection against chronic viral challenge.
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With resistance to most antimalarials increasing, it is imperative that new drugs are developed. We previously identified an aryl acetamide compound, MMV006833 (M-833), that inhibited the ring-stage development of newly invaded merozoites. Here, we select parasites resistant to M-833 and identify mutations in the START lipid transfer protein (PF3D7_0104200, PfSTART1). Introducing PfSTART1 mutations into wildtype parasites reproduces resistance to M-833 as well as to more potent analogues. PfSTART1 binding to the analogues is validated using organic solvent-based Proteome Integral Solubility Alteration (Solvent PISA) assays. Imaging of invading merozoites shows the inhibitors prevent the development of ring-stage parasites potentially by inhibiting the expansion of the encasing parasitophorous vacuole membrane. The PfSTART1-targeting compounds also block transmission to mosquitoes and with multiple stages of the parasite's lifecycle being affected, PfSTART1 represents a drug target with a new mechanism of action.
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Acetamidas , Antimaláricos , Plasmodium falciparum , Proteínas Protozoarias , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , Plasmodium falciparum/metabolismo , Plasmodium falciparum/crecimiento & desarrollo , Acetamidas/farmacología , Acetamidas/química , Proteínas Protozoarias/metabolismo , Proteínas Protozoarias/genética , Antimaláricos/farmacología , Antimaláricos/química , Animales , Proteínas Portadoras/metabolismo , Proteínas Portadoras/genética , Mutación , Malaria Falciparum/parasitología , Malaria Falciparum/prevención & control , Malaria Falciparum/tratamiento farmacológico , Humanos , Resistencia a Medicamentos/genética , Resistencia a Medicamentos/efectos de los fármacos , Estadios del Ciclo de Vida/efectos de los fármacosRESUMEN
Necroptosis is a lytic form of regulated cell death reported to contribute to inflammatory diseases of the gut, skin and lung, as well as ischemic-reperfusion injuries of the kidney, heart and brain. However, precise identification of the cells and tissues that undergo necroptotic cell death in vivo has proven challenging in the absence of robust protocols for immunohistochemical detection. Here, we provide automated immunohistochemistry protocols to detect core necroptosis regulators - Caspase-8, RIPK1, RIPK3 and MLKL - in formalin-fixed mouse and human tissues. We observed surprising heterogeneity in protein expression within tissues, whereby short-lived immune barrier cells were replete with necroptotic effectors, whereas long-lived cells lacked RIPK3 or MLKL expression. Local changes in the expression of necroptotic effectors occurred in response to insults such as inflammation, dysbiosis or immune challenge, consistent with necroptosis being dysregulated in disease contexts. These methods will facilitate the precise localisation and evaluation of necroptotic signaling in vivo.
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Inmunohistoquímica , Necroptosis , Proteína Serina-Treonina Quinasas de Interacción con Receptores , Animales , Humanos , Ratones , Proteína Serina-Treonina Quinasas de Interacción con Receptores/metabolismo , Proteína Serina-Treonina Quinasas de Interacción con Receptores/genética , Inmunohistoquímica/métodos , Proteínas Quinasas/metabolismo , Proteínas Quinasas/genética , Caspasa 8/metabolismo , Transducción de Señal , Ratones Endogámicos C57BLRESUMEN
BACKGROUND: Diabetes is the eighth leading cause of death and has a substantial impact on the U.S. health care system. Recent changes to major insurance formularies allow for increased access to continuous glucose monitors (CGMs). Community pharmacists routinely assist and educate patients about diabetes care, including usage of CGM. OBJECTIVES: The purpose of this study was to evaluate the clinical impact of a community pharmacist remote CGM monitoring service on patients' glycemic metrics. Patient completion of comprehensive diabetes standards of care and pharmacist interventions and recommendations were assessed as secondary objectives. METHODS: This study was a prospective, feasibility study conducted at two pharmacies within 1 regional division of a large community pharmacy chain between November 2022 and June 2023. A pharmacist conducted patient enrollment visits and remotely monitored CGM glycemic metrics via cloud-based platforms per the study protocol. CGM glycemic metrics were evaluated for each patient 3 months pre- and post-study enrollment, including time above range (TAR), time in range (TIR), time below range, glucose management indicator, average glucose, CGM utilization rate, and glucose variability. Metrics were evaluated for statistical significance using the Wilcoxon signed-rank test and descriptive statistics. RESULTS: Pharmacists enrolled 36 patients in this study with 20 patients completing the full 3-month study period per protocol. There was a statistically significant improvement in three of eight glycemic metrics (very high TAR, TIR, and average glucose). Specifically, TIR had the largest improvement from 61.8% pre-enrollment to 69.9% (P < 0.006) postenrollment. All other pertinent glycemic metrics displayed improvements but were not statistically significant. CONCLUSION: The results demonstrate clinically and statistically significant improvements in several glycemic metrics for patients who participated in the community pharmacist-led remote CGM monitoring service, which may result in improved diabetes control and fewer long-term diabetes-related health complications.
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Mutations in genes encoding chromatin modifiers are enriched among mutations causing intellectual disability. The continuing development of the brain postnatally, coupled with the inherent reversibility of chromatin modifications, may afford an opportunity for therapeutic intervention following a genetic diagnosis. Development of treatments requires an understanding of protein function and models of the disease. Here, we provide a mouse model of Say-Barber-Biesecker-Young-Simpson syndrome (SBBYSS) (OMIM 603736) and demonstrate proof-of-principle efficacy of postnatal treatment. SBBYSS results from heterozygous mutations in the KAT6B (MYST4/MORF/QFK) gene and is characterized by intellectual disability and autism-like behaviors. Using human cells carrying SBBYSS-specific KAT6B mutations and Kat6b heterozygous mice (Kat6b+/-), we showed that KAT6B deficiency caused a reduction in histone H3 lysine 9 acetylation. Kat6b+/- mice displayed learning, memory, and social deficits, mirroring SBBYSS individuals. Treatment with a histone deacetylase inhibitor, valproic acid, or an acetyl donor, acetyl-carnitine (ALCAR), elevated histone acetylation levels in the human cells with SBBYSS mutations and in brain and blood cells of Kat6b+/- mice and partially reversed gene expression changes in Kat6b+/- cortical neurons. Both compounds improved sociability in Kat6b+/- mice, and ALCAR treatment restored learning and memory. These data suggest that a subset of SBBYSS individuals may benefit from postnatal therapeutic interventions.
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Anomalías Múltiples , Acetilcarnitina , Hipotiroidismo Congénito , Anomalías Craneofaciales , Histona Acetiltransferasas , Discapacidad Intelectual , Inestabilidad de la Articulación , Animales , Humanos , Ratones , Anomalías Múltiples/tratamiento farmacológico , Anomalías Múltiples/genética , Acetilación , Acetilcarnitina/farmacología , Acetilcarnitina/uso terapéutico , Blefarofimosis , Cromatina , Anomalías Craneofaciales/tratamiento farmacológico , Anomalías Craneofaciales/genética , Exones , Facies , Cardiopatías Congénitas , Histona Acetiltransferasas/antagonistas & inhibidores , Histona Acetiltransferasas/genética , Histona Acetiltransferasas/metabolismo , Histonas/genética , Discapacidad Intelectual/tratamiento farmacológico , Discapacidad Intelectual/genéticaRESUMEN
EphB6 is an understudied ephrin receptor tyrosine pseudokinase that is downregulated in multiple types of metastatic cancers. Unlike its kinase-active counterparts which autophosphorylate and transmit signals upon intercellular interaction, little is known about how EphB6 functions in the absence of intrinsic kinase activity. Here, we unveil a molecular mechanism of cell-cell interaction driven by EphB6. We identify ephrinB1 as a cognate ligand of EphB6 and show that in trans interaction of EphB6 with ephrinB1 on neighboring cells leads to the formation of large co-clusters at the plasma membrane. These co-clusters exhibit a decreased propensity towards endocytosis, suggesting a unique characteristic for this type of cell-cell interaction. Using lattice light-sheet microscopy, 3D structured illumination microscopy and cryo-electron tomography techniques, we show that co-clustering of EphB6 and ephrinB1 promotes the formation of double-membrane tubular structures between cells. Importantly, we also demonstrate that these intercellular structures stabilize cell-cell adhesion, leading to a reduction in the invasive behavior of cancer cells. Our findings rationalize a role for EphB6 pseudokinase as a tumor suppressor when interacting with its ligands in trans.
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Fosforilación , Invasividad NeoplásicaRESUMEN
ABSTRACT: Peripheral arterial disease (PAD) is the third leading cause of atherosclerotic morbidity after coronary heart disease and stroke yet is widely underdiagnosed and undertreated. Treatment of risk factors such as diabetes and cigarette smoking can benefit patients with PAD. Patients should have adequate blood pressure and lipid control to decrease clinical manifestations and symptoms of PAD. Use of antithrombotic medications should be individualized to the patient depending on the presence of symptoms, revascularization, and comorbidities. All patient care providers, including physicians, pharmacists, nurse practitioners, and physician assistants, should incorporate PAD screening in their at-risk patients to improve access for appropriate earlier diagnosis, initiation of guideline directed therapy, and risk factor modification to reduce both major adverse CV and limb outcomes. The purpose of this narrative review is to provide an overview of PAD and summarize clinical trial evidence and guideline recommendations for screening and treatment to increase awareness among health care providers to ultimately have a positive impact on patient care.
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Enfermedad Arterial Periférica , Humanos , Fibrinolíticos/uso terapéutico , Fibrinolíticos/efectos adversos , Enfermedad Arterial Periférica/terapia , Enfermedad Arterial Periférica/diagnóstico , Enfermedad Arterial Periférica/epidemiología , Enfermedad Arterial Periférica/fisiopatología , Enfermedad Arterial Periférica/tratamiento farmacológico , Guías de Práctica Clínica como Asunto , Medición de Riesgo , Factores de Riesgo , Conducta de Reducción del Riesgo , Resultado del TratamientoRESUMEN
OBJECTIVE: This study aimed to evaluate the impact of American Heart Association (AHA) advanced cardiovascular life support (ACLS) education and training on long-term retention of ACLS knowledge and confidence in Doctor of Pharmacy (PharmD) students. METHODS: This multicenter study included PharmD students who received ACLS training through different means: 1-hour didactic lecture (didactic), 1-hour didactic lecture with 2-hour skills practice (didactic + skills), and comprehensive AHA ACLS certification through an elective course (elective-certification). Students completed a survey before training, immediately after training, and at least 6-12 months after training to assess demographics and ACLS confidence and knowledge. The primary outcome was a passing score, defined as ≥ 84% on the long-term knowledge assessment. Secondary outcomes included overall knowledge score and perceived confidence, assessed using the Dreyfus model. RESULTS: The long-term assessment was completed by 160 students in the didactic group, 66 in the didactic + skills group, and 62 in the elective-certification group. Six (4%), 8 (12%), and 14 (23%) received a passing score on the long-term knowledge assessment in the didactic, didactic + skills, and elective-certification groups, respectively. The median (IQR) scores on the long-term knowledge assessment were 50% (40-60), 60% (50-70), and 65% (40-80) in the 3 groups. On the long-term assessment, confidence was higher in the elective-certification group, demonstrated by more self-ratings of competent, proficient, and expert, and fewer self-ratings of novice and advanced beginner. CONCLUSION: Long-term retention of ACLS knowledge was low in all groups, but was higher in students who received AHA ACLS certification through an ACLS elective course.
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Educación en Farmacia , Estudiantes de Farmacia , Humanos , Apoyo Vital Cardíaco Avanzado/educación , Evaluación Educacional , CurriculumRESUMEN
OBJECTIVE: We undertook this study to validate the Pediatric Arthritis Ultrasound Scoring System for the knee joint (PAUSS-knee) in children with juvenile idiopathic arthritis (JIA). METHODS: Children with JIA were enrolled to prospectively receive a musculoskeletal ultrasound (MSUS) examination of the knee and a physical examination to determine presence/absence of clinical arthritis. MSUS images were scored using the PAUSS-knee, a semiquantitative MSUS scoring system (0-3, normal to severe) for B-mode and power Doppler mode. In addition to MSUS, a subset of participants also received magnetic resonance imaging (MRI) of the knee, which was scored according to the combined Juvenile Arthritis MRI Scoring (JAMRIS) system. Spearman's correlations (rs ) were used to calculate associations between variables. Test characteristics of the PAUSS-knee were calculated with MRI as the reference standard. Inflammatory biomarkers were assessed in synovial fluid from involved knees. RESULTS: Eighty children with JIA contributed 112 MSUSs and 25 MRIs of the knee. Of the knees, 41% (n = 46) had clinical evidence of arthritis. The B-mode PAUSS-knee score moderately correlated with clinically determined arthritis (rs = 0.54, P < 0.001) and strongly correlated with the JAMRIS score (rs = 0.75, P < 0.001). Compared with MRI, the area under the curve for the B-mode PAUSS-knee was 0.92. For a cutoff of >1, the B-mode PAUSS-knee had a sensitivity of 83% and specificity of 82%. Biomarker analysis indicates that interleukin-2R levels correlate with PAUSS score. CONCLUSION: Our data indicate that the PAUSS-knee has excellent accuracy for the diagnosis of arthritis when compared with MRI. The PAUSS-knee has the potential to effectively inform JIA medical decision-making in real time.
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Artritis Juvenil , Humanos , Niño , Artritis Juvenil/diagnóstico por imagen , Artritis Juvenil/patología , Articulación de la Rodilla/diagnóstico por imagen , Articulación de la Rodilla/patología , Imagen por Resonancia Magnética/métodos , Ultrasonografía , BiomarcadoresRESUMEN
ZRANB1 (human Trabid) missense mutations have been identified in children diagnosed with a range of congenital disorders including reduced brain size, but how Trabid regulates neurodevelopment is not understood. We have characterized these patient mutations in cells and mice to identify a key role for Trabid in the regulation of neurite growth. One of the patient mutations flanked the catalytic cysteine of Trabid and its deubiquitylating (DUB) activity was abrogated. The second variant retained DUB activity, but failed to bind STRIPAK, a large multiprotein assembly implicated in cytoskeleton organization and neural development. Zranb1 knock-in mice harboring either of these patient mutations exhibited reduced neuronal and glial cell densities in the brain and a motor deficit consistent with fewer dopaminergic neurons and projections. Mechanistically, both DUB-impaired and STRIPAK-binding-deficient Trabid variants impeded the trafficking of adenomatous polyposis coli (APC) to microtubule plus-ends. Consequently, the formation of neuronal growth cones and the trajectory of neurite outgrowth from mutant midbrain progenitors were severely compromised. We propose that STRIPAK recruits Trabid to deubiquitylate APC, and that in cells with mutant Trabid, APC becomes hyperubiquitylated and mislocalized causing impaired organization of the cytoskeleton that underlie the neuronal and developmental phenotypes.
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Poliposis Adenomatosa del Colon , Neuritas , Animales , Niño , Humanos , Ratones , Poliposis Adenomatosa del Colon/metabolismo , Proteína de la Poliposis Adenomatosa del Colon/genética , Proteína de la Poliposis Adenomatosa del Colon/metabolismo , Axones/metabolismo , Mutación , Neuritas/metabolismoRESUMEN
The diversity of COVID-19 disease in otherwise healthy people, from seemingly asymptomatic infection to severe life-threatening disease, is not clearly understood. We passaged a naturally occurring near-ancestral SARS-CoV-2 variant, capable of infecting wild-type mice, and identified viral genomic mutations coinciding with the acquisition of severe disease in young adult mice and lethality in aged animals. Transcriptomic analysis of lung tissues from mice with severe disease elucidated a host antiviral response dominated mainly by interferon and IL-6 pathway activation in young mice, while in aged animals, a fatal outcome was dominated by TNF and TGF-ß signaling. Congruent with our pathway analysis, we showed that young TNF-deficient mice had mild disease compared to controls and aged TNF-deficient animals were more likely to survive infection. Emerging clinical correlates of disease are consistent with our preclinical studies, and our model may provide value in defining aberrant host responses that are causative of severe COVID-19.
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COVID-19 , SARS-CoV-2 , Adulto Joven , Humanos , Ratones , Animales , Anciano , SARS-CoV-2/genética , COVID-19/genética , Virulencia/genética , Mutación , Modelos Animales de EnfermedadRESUMEN
With emerging resistance to frontline treatments, it is vital that new antimalarial drugs are identified to target Plasmodium falciparum. We have recently described a compound, MMV020291, as a specific inhibitor of red blood cell (RBC) invasion, and have generated analogues with improved potency. Here, we generated resistance to MMV020291 and performed whole genome sequencing of 3 MMV020291-resistant populations. This revealed 3 nonsynonymous single nucleotide polymorphisms in 2 genes; 2 in profilin (N154Y, K124N) and a third one in actin-1 (M356L). Using CRISPR-Cas9, we engineered these mutations into wild-type parasites, which rendered them resistant to MMV020291. We demonstrate that MMV020291 reduces actin polymerisation that is required by the merozoite stage parasites to invade RBCs. Additionally, the series inhibits the actin-1-dependent process of apicoplast segregation, leading to a delayed death phenotype. In vitro cosedimentation experiments using recombinant P. falciparum proteins indicate that potent MMV020291 analogues disrupt the formation of filamentous actin in the presence of profilin. Altogether, this study identifies the first compound series interfering with the actin-1/profilin interaction in P. falciparum and paves the way for future antimalarial development against the highly dynamic process of actin polymerisation.
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Antimaláricos , Malaria Falciparum , Humanos , Plasmodium falciparum/metabolismo , Actinas/genética , Actinas/metabolismo , Profilinas/genética , Profilinas/metabolismo , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/prevención & control , Malaria Falciparum/genética , Eritrocitos/parasitología , Antimaláricos/farmacologíaRESUMEN
BACKGROUND: Patella alta is an anatomic risk factor for patellar instability in adolescents that is also linked to the risk factor of trochlear dysplasia. This study aims to determine the age of onset and age-related incidence of patella alta in a pediatric population of patients with patellar instability. We hypothesized that patellar height ratios would not increase with age, suggesting a congenital rather than the developmental origin of patella alta. METHODS: A retrospective cross-sectional cohort of patients was collected with the following inclusion criteria: patients aged 5 to 18 who had a knee magnetic resonance imaging performed from 2000 to 2022 and the International Classification of Diseases code for patellar dislocation. Demographic information and details of the patellar instability episode(s) were collected with a chart review. Sagittal magnetic resonance imaging was used to measure Caton-Deschamps Index (CDI) and the Insall-Salvati Ratio (ISR) by 2 observers. Data were analyzed to assess for associations between patellar height ratios and age of the first dislocation and to assess if the proportion of patients categorized as having patella alta changed with age. RESULTS: The 140 knees included in the cohort had an average age of 13.9 years (SD=2.40; range: 8-18) and were 55% female. Patella alta was present in 78 knees (55.7%) using CDI>=1.2 and in 59 knees (42.1%) using ISR>=1.3. The earliest age patella alta was observed was at age 8 using CDI>=1.2 and age 10 using ISR>=1.3. There were no statistically significant associations between CDI and age without adjustment ( P =0.14) nor after adjustment for sex and body mass index ( P =0.17). The proportion of knees above the CDI threshold for patella alta to the knees below the cutoff did not show a significant change with age ( P =0.09). CONCLUSIONS: Patella alta, as defined by CDI, is seen in patients as young as 8 years old. Patellar height ratios do not change with age in patients with patellar dislocation, suggesting that patella alta is established at a young age rather than developing during the adolescent years. LEVEL OF EVIDENCE: Level III-diagnostic, cross-sectional.
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Inestabilidad de la Articulación , Luxación de la Rótula , Articulación Patelofemoral , Adolescente , Humanos , Niño , Femenino , Masculino , Luxación de la Rótula/diagnóstico por imagen , Luxación de la Rótula/complicaciones , Inestabilidad de la Articulación/diagnóstico por imagen , Inestabilidad de la Articulación/epidemiología , Inestabilidad de la Articulación/etiología , Rótula/diagnóstico por imagen , Estudios Retrospectivos , Estudios Transversales , TibiaRESUMEN
Mutant TP53 proteins are thought to drive the development and sustained expansion of cancers at least in part through the loss of the wild-type (wt) TP53 tumour suppressive functions. Therefore, compounds that can restore wt TP53 functions in mutant TP53 proteins are expected to inhibit the expansion of tumours expressing mutant TP53. APR-246 has been reported to exert such effects in malignant cells and is currently undergoing clinical trials in several cancer types. However, there is evidence that APR-246 may also kill malignant cells that do not express mutant TP53. To support the clinical development of APR-246 it is important to understand its mechanism(s) of action. By establishing isogenic background tumour cell lines with different TP53/TRP53 states, we found that APR-246 can kill malignant cells irrespective of their TP53/TRP53 status. Accordingly, RNAseq analysis revealed that treatment with APR-246 induces expression of the same gene set in Eµ-Myc mouse lymphoma cells of all four possible TRP53 states, wt, wt alongside mutant, knockout and knockout alongside mutant. We found that depending on the type of cancer cell and the concentration of APR-246 used, this compound can kill malignant cells through induction of various programmed cell death pathways, including apoptosis, necroptosis and ferroptosis. The sensitivity of non-transformed cells to APR-246 also depended on the cell type. These findings reveal that the clinical testing of APR-246 should not be limited to cancers expressing mutant TP53 but expanded to cancers that express wt TP53 or are TP53-deficient.
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Genes p53 , Proteína p53 Supresora de Tumor , Animales , Ratones , Proteína p53 Supresora de Tumor/genética , Proteína p53 Supresora de Tumor/metabolismo , Apoptosis , Línea Celular Tumoral , MutaciónRESUMEN
The most severe form of malaria is caused by Plasmodium falciparum. These parasites invade human erythrocytes, and an essential step in this process involves the ligand PfRh5, which forms a complex with cysteine-rich protective antigen (CyRPA) and PfRh5-interacting protein (PfRipr) (RCR complex) and binds basigin on the host cell. We identified a heteromeric disulfide-linked complex consisting of P. falciparum Plasmodium thrombospondin-related apical merozoite protein (PfPTRAMP) and P. falciparum cysteine-rich small secreted protein (PfCSS) and have shown that it binds RCR to form a pentameric complex, PCRCR. Using P. falciparum lines with conditional knockouts, invasion inhibitory nanobodies to both PfPTRAMP and PfCSS, and lattice light-sheet microscopy, we show that they are essential for merozoite invasion. The PCRCR complex functions to anchor the contact between merozoite and erythrocyte membranes brought together by strong parasite deformations. We solved the structure of nanobody-PfCSS complexes to identify an inhibitory epitope. Our results define the function of the PCRCR complex and identify invasion neutralizing epitopes providing a roadmap for structure-guided development of these proteins for a blood stage malaria vaccine.
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Antígenos de Grupos Sanguíneos , Vacunas contra la Malaria , Malaria Falciparum , Humanos , Plasmodium falciparum/genética , Cisteína , Eritrocitos , EpítoposRESUMEN
Tryptophan C-mannosylation stabilizes proteins bearing a thrombospondin repeat (TSR) domain in metazoans. Here we show that Plasmodium falciparum expresses a DPY19 tryptophan C-mannosyltransferase in the endoplasmic reticulum and that DPY19-deficiency abolishes C-glycosylation, destabilizes members of the TRAP adhesin family and inhibits transmission to mosquitoes. Imaging P. falciparum gametogenesis in its entirety in four dimensions using lattice light-sheet microscopy reveals defects in ΔDPY19 gametocyte egress and exflagellation. While egress is diminished, ΔDPY19 microgametes still fertilize macrogametes, forming ookinetes, but these are abrogated for mosquito infection. The gametogenesis defects correspond with destabilization of MTRAP, which we show is C-mannosylated in P. falciparum, and the ookinete defect is concordant with defective CTRP secretion on the ΔDPY19 background. Genetic complementation of DPY19 restores ookinete infectivity, sporozoite production and C-mannosylation activity. Therefore, tryptophan C-mannosylation by DPY19 ensures TSR protein quality control at two lifecycle stages for successful transmission of the human malaria parasite.
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Culicidae , Malaria Falciparum , Animales , Culicidae/metabolismo , Glicosilación , Humanos , Malaria Falciparum/parasitología , Plasmodium falciparum/genética , Plasmodium falciparum/metabolismo , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Trombospondinas/metabolismo , Triptófano/metabolismoRESUMEN
High-throughput methodologies are the cornerstone of screening approaches to identify novel compounds that regulate immune cell function. To identify novel targeted therapeutics to treat immune disorders and haematological malignancies, there is a need to integrate functional cellular information with the molecular mechanisms that regulate changes in immune cell phenotype. We facilitate this goal by combining quantitative methods for dissecting complex simultaneous cell phenotypic effects with genomic analysis. This combination strategy we term Multiplexed Analysis of Cells sequencing (MAC-seq), a modified version of Digital RNA with perturbation of Genes (DRUGseq). We applied MAC-seq to screen compounds that target the epigenetic machinery of B cells and assess altered humoral immunity by measuring changes in proliferation, survival, differentiation and transcription. This approach revealed that polycomb repressive complex 2 (PRC2) inhibitors promote antibody secreting cell (ASC) differentiation in both murine and human B cells in vitro. This is further validated using T cell-dependent immunization in mice. Functional dissection of downstream effectors of PRC2 using arrayed CRISPR screening uncovered novel regulators of B cell differentiation, including Mybl1, Myof, Gas7 and Atoh8. Together, our findings demonstrate that integrated phenotype-transcriptome analyses can be effectively combined with drug screening approaches to uncover the molecular circuitry that drives lymphocyte fate decisions.