RESUMEN
Aberrant increase of arachidonic acid (ARA) has long been implicated in the pathology of Alzheimer's disease (AD), while the underlying causal mechanism remains unclear. In this study, we revealed a link between ARA mobilization and microglial dysfunction in Aß pathology. Lipidomic analysis of primary microglia from AppNL-GF mice showed a marked increase in free ARA and lysophospholipids (LPLs) along with a decrease in ARA-containing phospholipids, suggesting increased ARA release from phospholipids (PLs). To manipulate ARA-containing PLs in microglia, we genetically deleted lysophosphatidylcholine acyltransferase 3 (Lpcat3), the main enzyme catalyzing the incorporation of ARA into PLs. Loss of microglial Lpcat3 reduced the levels of ARA-containing PLs, free ARA and LPLs, leading to a compensatory increase in monounsaturated fatty acid (MUFA)-containing PLs in both male and female App NL-GF mice. Notably, the reduction of ARA in microglia significantly ameliorated oxidative stress and inflammatory responses while enhancing the phagocytosis of Aß plaques and promoting the compaction of Aß deposits. Mechanistically, scRNA seq suggested that LPCAT3 deficiency facilitates phagocytosis by facilitating de novo lipid synthesis while protecting microglia from oxidative damage. Collectively, our study reveals a novel mechanistic link between ARA mobilization and microglial dysfunction in AD. Lowering brain ARA levels through pharmacological or dietary interventions may be a potential therapeutic strategy to slow down AD progression.
Asunto(s)
1-Acilglicerofosfocolina O-Aciltransferasa , Péptidos beta-Amiloides , Ácido Araquidónico , Microglía , Animales , Microglía/metabolismo , Ratones , Ácido Araquidónico/metabolismo , Masculino , Femenino , Péptidos beta-Amiloides/metabolismo , 1-Acilglicerofosfocolina O-Aciltransferasa/metabolismo , 1-Acilglicerofosfocolina O-Aciltransferasa/genética , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Enfermedad de Alzheimer/genética , Ratones Transgénicos , Peroxidación de Lípido , Ratones Endogámicos C57BL , Estrés Oxidativo/fisiología , Fosfolípidos/metabolismoRESUMEN
Evidence-based home visiting services (EBHV) are available in states and localities nationwide through the federally-funded Maternal, Infant, and Early Childhood Home Visiting (MIECHV) program. Nevertheless, the anticipated benefits of EBHV, such as improved child developmental outcomes and increased positive parenting practices, may be undermined by the fact that most families withdraw from services earlier than the model developers planned. Prior studies have linked family attrition with staff turnover. The current study used a mixed methods design to investigate the conditions under which families remained active in the home visiting program after their assigned home visitor resigned. Coincidence Analysis revealed that giving families advance notice (at least 1 month) prior to the home visitors' upcoming resignation or developing a strong positive working alliance with the inheriting home visitor appears to independently make a difference for ongoing family engagement at 3 and 6 months following a staff transition. These findings suggest that emphasizing how staff turnover is managed may mitigate the risk of family withdrawal during these transitions.
Asunto(s)
Visita Domiciliaria , Reorganización del Personal , Humanos , Femenino , Masculino , Lactante , Familia , Adulto , PreescolarRESUMEN
Abnormalities of or reductions in GABAergic interneurons are implicated in the pathology of severe neuropsychiatric disorders, for which effective treatments are still elusive. Transplantation of human stem cell-derived interneurons is a promising cell-based therapy for treatment of these disorders. In mouse xenograft studies, human stem cell-derived-interneuron precursors could differentiate in vivo, but required a prolonged time of four to seven months to migrate from the graft site and integrate with the host tissue. This poses a serious roadblock for clinical translation of this approach. For transplantation to be effective, grafted neurons should migrate to affected areas at a faster rate. We have previously shown that endothelial cells of the periventricular vascular network are the natural substrates for GABAergic interneurons in the developing mouse forebrain, and provide valuable guidance cues for their long-distance migration. In addition, periventricular endothelial cells house a GABA signaling pathway with direct implications for psychiatric disease origin. In this study we translated this discovery into human, with significant therapeutic implications. We generated human periventricular endothelial cells, using human pluripotent stem cell technology, and extensively characterized its molecular, cellular, and functional properties. Co-culture of human periventricular endothelial cells with human interneurons significantly accelerated interneuron migration in vitro and led to faster migration and wider distribution of grafted interneurons in vivo, compared to neuron-only transplants. Furthermore, the co-transplantation strategy was able to rescue abnormal behavioral symptoms in a pre-clinical model of psychiatric disorder, within 1 month after transplantation. We anticipate this strategy to open new doors and facilitate exciting advances in angiogenesis-mediated treatment of psychiatric disorders.
Asunto(s)
Neuronas GABAérgicas , Trastornos Mentales , Animales , Movimiento Celular , Células Endoteliales , Humanos , Interneuronas , Trastornos Mentales/terapia , Ratones , ProsencéfaloRESUMEN
The aPKC [atypical PKC (protein kinase C)] isoforms ι and ζ play crucial roles in the formation and maintenance of cell polarity and represent attractive anti-oncogenic drug targets in Ras-dependent tumours. To date, few isoform-specific chemical biology tools are available to inhibit aPKC catalytic activity. In the present paper, we describe the identification and functional characterization of potent and selective thieno[2,3-d]pyrimidine-based chemical inhibitors of aPKCs. A crystal structure of human PKCι kinase domain bound to a representative compound, CRT0066854, reveals the basis for potent and selective chemical inhibition. Furthermore, CRT0066854 displaces a crucial Asn-Phe-Asp motif that is part of the adenosine-binding pocket and engages an acidic patch used by arginine-rich PKC substrates. We show that CRT0066854 inhibits the LLGL2 (lethal giant larvae 2) phosphorylation in cell lines and exhibits phenotypic effects in a range of cell-based assays. We conclude that this compound can be used as a chemical tool to modulate aPKC activity in vitro and in vivo and may guide the search for further aPKC-selective inhibitors.
Asunto(s)
Proteína Quinasa C/antagonistas & inhibidores , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/farmacología , Pirimidinas/química , Tiofenos/farmacología , Adenosina/metabolismo , Adenosina Trifosfato/química , Adenosina Trifosfato/metabolismo , Secuencia de Aminoácidos , Animales , Sitios de Unión , Línea Celular , Movimiento Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Cristalografía por Rayos X , Proteínas del Citoesqueleto/metabolismo , Perros , Evaluación Preclínica de Medicamentos/métodos , Ensayos Analíticos de Alto Rendimiento , Humanos , Concentración 50 Inhibidora , Isoenzimas/antagonistas & inhibidores , Imitación Molecular , Datos de Secuencia Molecular , Fosforilación , Proteína Quinasa C/química , Proteína Quinasa C/metabolismo , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/metabolismo , Pirimidinas/farmacología , Tiofenos/químicaRESUMEN
This study assessed the effectiveness of Safe@Home, an in-home intervention to (1) prevent out-of-home placement for children at imminent risk of placement, and (2) minimize time in out-of-home care for children already in foster care. Using Coarsened Exact Matching, children who received Safe@Home were matched to a comparison group of children served before Safe@Home was available in their community. All children were determined by the child welfare agency to be unsafe and in need of immediate intervention. The matched samples (Safe@Home n = 510, Comparison n = 851) showed strong baseline equivalence on child age, race/ethnicity, previous history of child welfare involvement, and safety threats. Children who received Safe@Home experienced lower rate of out-of-home placements, higher rate of permanency with a parent (sustained for 12 months after the end of Safe@Home), fewer days in out-of-home care, and shorter time to case closure relative to children who received treatment as usual. There was no effect of Safe@Home on post-permanency outcomes of maltreatment and entry or re-entry after case closure.
Asunto(s)
Maltrato a los Niños , Niño , Humanos , Maltrato a los Niños/prevención & control , Protección a la Infancia , Cuidados en el Hogar de Adopción , Servicios de Protección Infantil , PadresRESUMEN
The discovery of MICU1 as gatekeeper of mitochondrial calcium (mCa2+) entry has transformed our understanding of mCa2+ flux. Recent studies revealed an additional role of MICU1 as a Ca2+ sensor at MICOS (mitochondrial contact site and cristae organizing system). MICU1's presence at MICOS suggests its involvement in coordinating Ca2+ signaling and mitochondrial ultrastructure. Besides its role in Ca2+ regulation, MICU1 influences cellular signaling pathways including transcription, epigenetic regulation, metabolism, and cell death, thereby affecting human health. Here, we summarize recent findings on MICU1's canonical and noncanonical functions, and its relevance to human health and diseases.
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Señalización del Calcio , Proteínas de Unión al Calcio , Calcio , Mitocondrias , Proteínas de Transporte de Membrana Mitocondrial , Humanos , Mitocondrias/metabolismo , Calcio/metabolismo , Proteínas de Transporte de Membrana Mitocondrial/metabolismo , Proteínas de Transporte de Membrana Mitocondrial/genética , Proteínas de Unión al Calcio/metabolismo , Proteínas de Unión al Calcio/genética , Animales , Proteínas de Transporte de Catión/metabolismo , Proteínas de Transporte de Catión/genética , Proteínas de Transporte de Catión/químicaRESUMEN
Brain-derived extracellular vesicles (EVs) play an active role in Alzheimer's disease (AD), relaying important physiological information about their host tissues. The internal cargo of EVs is protected from degradation, making EVs attractive AD biomarkers. However, it is unclear how circulating EVs relate to EVs isolated from disease-vulnerable brain regions. We developed a novel method for collecting EVs from the hippocampal interstitial fluid (ISF) of live mice. EVs (EVISF ) were isolated via ultracentrifugation and characterized by nanoparticle tracking analysis, immunogold labelling, and flow cytometry. Mass spectrometry and proteomic analyses were performed on EVISF cargo. EVISF were 40-150 nm in size and expressed CD63, CD9, and CD81. Using a model of cerebral amyloidosis (e.g., APPswe, PSEN1dE9 mice), we found protein concentration increased but protein diversity decreased with Aß deposition. Genotype, age, and Aß deposition modulated proteostasis- and immunometabolic-related pathways. Changes in the microglial EVISF proteome were sexually dimorphic and associated with a differential response of plaque associated microglia. We found that female APP/PS1 mice have more amyloid plaques, less plaque associated microglia, and a less robust- and diverse- EVISF microglial proteome. Thus, in vivo microdialysis is a novel technique for collecting EVISF and offers a unique opportunity to explore the role of EVs in AD.
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Enfermedad de Alzheimer , Vesículas Extracelulares , Placa Aterosclerótica , Femenino , Animales , Ratones , Proteoma , Líquido Extracelular , Microglía , Proteómica , HipocampoRESUMEN
The study was done to determine the association between religiosity and behaviors likely to reduce new HIV infections among 1,224 Muslim youth. Respondents with Sujda, the hyperpigmented spot on the forehead due to prostration during prayers, were more likely to abstain from sex, be faithful in marriage, and avoid alcohol and narcotics. Males wearing a Muslim cap were more likely to abstain from sex and avoid alcohol and narcotics. Females wearing the long dress (Hijab) were also more likely to avoid alcohol. This data should be used by stakeholders in promoting behaviors likely to reduce new HIV infections among Muslims.
Asunto(s)
Conducta del Adolescente/psicología , Infecciones por VIH/prevención & control , Infecciones por VIH/psicología , Conductas Relacionadas con la Salud , Promoción de la Salud/métodos , Religión y Medicina , Adolescente , Adulto , Actitud Frente a la Salud , Femenino , Humanos , Islamismo , Masculino , Matrimonio/psicología , Factores de Riesgo , Distribución por Sexo , Conducta Sexual/psicología , Factores Socioeconómicos , Trastornos Relacionados con Sustancias/psicología , Uganda , Adulto JovenRESUMEN
Brain-derived extracellular vesicles (EVs) play an active role in Alzheimer's disease (AD), relaying important physiological information about their host tissues. Circulating EVs are protected from degradation, making them attractive AD biomarkers. However, it is unclear how circulating EVs relate to EVs isolated from disease-vulnerable brain regions. We developed a novel method for collecting EVs from the hippocampal interstitial fluid (ISF) of live mice. EVs (EVISF) were isolated via ultracentrifugation and characterized by nanoparticle tracking analysis, immunogold labeling, and flow cytometry. Mass spectrometry and proteomic analyses were performed on EVISF cargo. EVISF were 40-150 nm in size and expressed CD63, CD9, and CD81. Using a model of cerebral amyloidosis (e.g. APPswe,PSEN1dE9 mice), we found protein concentration increased but protein diversity decreased with A deposition. Genotype, age, and Aß deposition modulated proteostasis- and immunometabolic-related pathways. Changes in the microglial EVISF proteome were sexually dimorphic and associated with a differential response of plaque associated microglia. We found that female APP/PS1 mice have more amyloid plaques, less plaque associated microglia, and a less robust- and diverse- EVISF microglial proteome. Thus, in vivo microdialysis is a novel technique for collecting EVISF and offers a unique opportunity to explore the role of EVs in AD.
RESUMEN
Elevated blood glucose levels, or hyperglycemia, can increase brain excitability and amyloid-ß (Aß) release, offering a mechanistic link between type 2 diabetes and Alzheimer's disease (AD). Since the cellular mechanisms governing this relationship are poorly understood, we explored whether ATP-sensitive potassium (KATP) channels, which couple changes in energy availability with cellular excitability, play a role in AD pathogenesis. First, we demonstrate that KATP channel subunits Kir6.2/KCNJ11 and SUR1/ABCC8 were expressed on excitatory and inhibitory neurons in the human brain, and cortical expression of KCNJ11 and ABCC8 changed with AD pathology in humans and mice. Next, we explored whether eliminating neuronal KATP channel activity uncoupled the relationship between metabolism, excitability, and Aß pathology in a potentially novel mouse model of cerebral amyloidosis and neuronal KATP channel ablation (i.e., amyloid precursor protein [APP]/PS1 Kir6.2-/- mouse). Using both acute and chronic paradigms, we demonstrate that Kir6.2-KATP channels are metabolic sensors that regulate hyperglycemia-dependent increases in interstitial fluid levels of Aß, amyloidogenic processing of APP, and amyloid plaque formation, which may be dependent on lactate release. These studies identify a potentially new role for Kir6.2-KATP channels in AD and suggest that pharmacological manipulation of Kir6.2-KATP channels holds therapeutic promise in reducing Aß pathology in patients with diabetes or prediabetes.
Asunto(s)
Enfermedad de Alzheimer , Diabetes Mellitus Tipo 2 , Hiperglucemia , Humanos , Ratones , Animales , Canales KATP/metabolismo , Enfermedad de Alzheimer/patología , Diabetes Mellitus Tipo 2/complicaciones , Glucosa , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismoRESUMEN
State child welfare risk and safety assessment data were analyzed to determine three levels of in-home service that correspond to the Child Welfare League of America's (CWLA) national caseload standards and to evaluate the number of staff needed to provide services at each level. The analysis revealed that 50% additional case-carrying in-home services staff were needed to provide appropriate risk- and safety-based services to children in their own homes. Findings from this study were used by the state child welfare services agency to allocate vacant worker positions to local jurisdictions.
Asunto(s)
Servicios de Salud del Niño , Protección a la Infancia/estadística & datos numéricos , Necesidades y Demandas de Servicios de Salud/estadística & datos numéricos , Visita Domiciliaria/estadística & datos numéricos , Admisión y Programación de Personal/estadística & datos numéricos , Carga de Trabajo/estadística & datos numéricos , Niño , Maltrato a los Niños/prevención & control , Servicios de Salud del Niño/estadística & datos numéricos , Servicios de Salud del Niño/tendencias , Protección a la Infancia/tendencias , Necesidades y Demandas de Servicios de Salud/tendencias , Visita Domiciliaria/tendencias , Humanos , Admisión y Programación de Personal/tendencias , Riesgo , Estados Unidos , Recursos HumanosRESUMEN
The mitochondrial phosphopantetheinyl transferase gene pptB of the opportunistic pathogen Aspergillus fumigatus has been identified and characterised. Unlike pptA, which is required for lysine biosynthesis, secondary metabolism, and iron assimilation, pptB is essential for viability. PptB is located in the mitochondria. In vitro expression of pptA and pptB has shown that PptB is specific for the mitochondrial acyl carrier protein AcpA.
Asunto(s)
Aspergillus fumigatus/enzimología , Proteínas Bacterianas/metabolismo , Mitocondrias/enzimología , Transferasas (Grupos de Otros Fosfatos Sustitutos)/metabolismo , Proteína Transportadora de Acilo/metabolismo , Aspergillus fumigatus/genética , Aspergillus fumigatus/fisiología , Proteínas Bacterianas/genética , Viabilidad Microbiana , Especificidad por Sustrato , Transferasas (Grupos de Otros Fosfatos Sustitutos)/genéticaRESUMEN
Intrinsic defects within blood vessels from the earliest developmental time points can directly contribute to psychiatric disease origin. Here, we show that nicotinamide adenine dinucleotide (NAD+), administered during a critical window of prenatal development, in a mouse model with dysfunctional endothelial γ-aminobutyric acid type A (GABAA) receptors (Gabrb3 endothelial cell knockout mice), results in a synergistic repair of impaired angiogenesis and normalization of brain development, thus preventing the acquisition of abnormal behavioral symptoms. The prenatal NAD+ treatment stimulated extensive cellular and molecular changes in endothelial cells and restored blood vessel formation, GABAergic neuronal development, and forebrain morphology by recruiting an alternate pathway for cellular repair, via previously unknown transcriptional mechanisms and purinergic receptor signaling. Our findings illustrate a novel and powerful role for NAD+ in sculpting prenatal brain development that has profound implications for rescuing brain blood flow in a permanent and irreversible manner, with long-lasting consequences for mental health outcome.
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Células Endoteliales , NAD , Animales , Células Endoteliales/metabolismo , Femenino , Neuronas GABAérgicas/metabolismo , Ratones , Ratones Noqueados , NAD/metabolismo , Embarazo , Prosencéfalo/metabolismo , Receptores de GABA-A/metabolismoRESUMEN
The mammalian main olfactory pathway detects myriad volatile chemicals using >1,000 odorant receptor (OR) genes, which are organized into two phylogenetically distinct classes (class I and class II). An important question is how these evolutionarily conserved classes contribute to odor perception. Here, we report functional inactivation of a large number of class I ORs in mice via identification and deletion of a local cis-acting enhancer in the class I gene cluster. This manipulation reduced expression of half of the 131 intact class I genes. The resulting class I-depleted mice exhibited a significant reduction in the number of glomeruli responding to carboxylic acids-chemicals associated with microbial action and body odors. These mice also exhibit a change in odor perception marked by a selective loss of behavioral aversion to these compounds. Together, our data demonstrate that class I ORs play a critical role in representing a class of biologically relevant chemosignals.
Asunto(s)
Ácidos Carboxílicos/metabolismo , Vías Olfatorias/fisiología , Percepción Olfatoria , Receptores Odorantes/genética , Animales , Femenino , Masculino , Ratones , Receptores Odorantes/metabolismoRESUMEN
Previous consensus statements on sports concussion have highlighted the importance of Attention Deficit Hyperactivity Disorder (ADHD) and loss of consciousness (LOC) as risk factors related to concussion management. The present study investigated how self-reported history of either ADHD diagnosis or history of previous concussion resulting in LOC influence baseline neurocognitive performance and self-reported symptoms. This analysis was performed retrospectively on data collected primarily from student-athletes, both Division 1 and club sports athletes. The dataset (n = 1460) is comprised of college students (age = 19.1 ± 1.4 years). Significant differences were found for composite scores on the ImPACT for both history of concussion (p = 0.016) and ADHD (p = 0.014). For concussion history, those with a previous concussion, non-LOC, performed better on the visual motor speed (p = 0.004). Those with diagnosis of ADHD performed worse on verbal memory (p = 0.001) and visual motor speed (p = 0.033). For total symptoms, concussion history (p < 0.001) and ADHD (p = 0.001) had an influence on total symptoms. Those with ADHD reported more symptoms for concussion history; those with previous LOC concussion reported more symptoms than those with non-LOC concussion (p = 0.003) and no history (p < 0.001). These results highlight the importance of baseline measures of neurocognitive function and symptoms in concussion management in order to account for pre-existing conditions such as ADHD and LOC from previous concussion that could influence these measures.
RESUMEN
Feline immunodeficiency virus (FIV) is a naturally occurring lentivirus of domestic and nondomestic feline species. Infection in domestic cats leads to immune dysfunction via mechanisms similar to those caused by human immunodeficiency virus (HIV) and, as such, is a valuable natural animal model for acquired immunodeficiency syndrome (AIDS) in humans. An association between FIV and an increased incidence of neoplasia has long been recognized, with frequencies of up to 20% in FIV-positive cats recorded in some studies. This is similar to the rate of neoplasia seen in HIV-positive individuals, and in both species neoplasia typically requires several years to arise. The most frequently reported type of neoplasia associated with FIV infection is lymphoma. Here we review the possible mechanisms involved in FIV lymphomagenesis, including the possible involvement of coinfections, notably those with gamma-herpesviruses.
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Virus de la Inmunodeficiencia Felina/fisiología , Linfoma/virología , Animales , Gatos , Modelos Animales de EnfermedadRESUMEN
Antifungal drugs acting via new mechanisms of action are urgently needed to combat the increasing numbers of severe fungal infections caused by pathogens such as Candida albicans. The phosphopantetheinyl transferase of Aspergillus fumigatus, encoded by the essential gene pptB, has previously been identified as a potential antifungal target. This study investigated the function of its orthologue in C. albicans, PPT2/C1_09480W by placing one allele under the control of the regulatable MET3 promoter, and deleting the remaining allele. The phenotypes of this conditional null mutant showed that, as in A. fumigatus, the gene PPT2 is essential for growth in C. albicans, thus fulfilling one aspect of an efficient antifungal target. The catalytic activity of Ppt2 as a phosphopantetheinyl transferase and the acyl carrier protein Acp1 as a substrate were demonstrated in a fluorescence transfer assay, using recombinant Ppt2 and Acp1 produced and purified from E.coli. A fluorescence polarisation assay amenable to high-throughput screening was also developed. Therefore we have identified Ppt2 as a broad-spectrum novel antifungal target and developed tools to identify inhibitors as potentially new antifungal compounds.
Asunto(s)
Antifúngicos/farmacología , Proteínas Bacterianas/antagonistas & inhibidores , Candida albicans/efectos de los fármacos , Candida albicans/enzimología , Transferasas (Grupos de Otros Fosfatos Sustitutos)/antagonistas & inhibidores , Secuencia de Aminoácidos , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Candida albicans/genética , Proteínas Portadoras , Biología Computacional , Activación Enzimática , Expresión Génica , Datos de Secuencia Molecular , Fenotipo , Regiones Promotoras Genéticas , Alineación de Secuencia , Eliminación de Secuencia , Especificidad por Sustrato , Transferasas (Grupos de Otros Fosfatos Sustitutos)/química , Transferasas (Grupos de Otros Fosfatos Sustitutos)/genética , Transferasas (Grupos de Otros Fosfatos Sustitutos)/metabolismoRESUMEN
The purpose of this paper was to examine the State of Maryland as a case study of sustained change efforts in the service delivery system for children with significant behavioral health needs and their families. A punctuated equilibrium paradigm is introduced to describe Maryland's behavioral health system transformation over the course of three decades. The context and specific strategies that characterized Maryland's execution of its recent Mental Health Transformation State Incentive Grant are highlighted. There is a discussion of one of the pinnacle achievements of Maryland's transformation efforts, the recent statewide establishment of care management entities for children with behavioral health challenges, and its implications for behavioral health in the context of health care reform changes. This case study illustrates how a state can systematically and incrementally develop systems of care for children and families that are values-based, sustainable, and flexible.
Asunto(s)
Medicina de la Conducta/organización & administración , Trastornos de la Conducta Infantil/terapia , Planes Estatales de Salud/organización & administración , Niño , Trastornos de la Conducta Infantil/diagnóstico , Trastornos de la Conducta Infantil/psicología , Conducta Cooperativa , Atención a la Salud/organización & administración , Financiación Gubernamental/organización & administración , Reforma de la Atención de Salud/organización & administración , Implementación de Plan de Salud/organización & administración , Humanos , Comunicación Interdisciplinaria , Liderazgo , Maryland , Evaluación de Programas y Proyectos de SaludRESUMEN
Dihydroxyacid dehydratase (DHAD) is a key enzyme in the branched-chain amino acid biosynthetic pathway that exists in a variety of organisms, including fungi, plants and bacteria, but not humans. In this study we identified four putative DHAD genes from the filamentous fungus Aspergillus fumigatus by homology to Saccharomyces cerevisiae ILV3. Two of these genes, AFUA_2G14210 and AFUA_1G03550, initially designated AfIlv3A and AfIlv3B for this study, clustered in the same group as S. cerevisiae ILV3 following phylogenetic analysis. To investigate the functions of these genes, AfIlv3A and AfIlv3B were knocked out in A. fumigatus. Deletion of AfIlv3B gave no apparent phenotype whereas the Δilv3A strain required supplementation with isoleucine and valine for growth. Thus, AfIlv3A is required for branched-chain amino acid synthesis in A. fumigatus. A recombinant AfIlv3A protein derived from AFUA_2G14210 was shown to have DHAD activity in an in vitro assay, confirming that AfIlv3A is a DHAD. In addition we show that mutants lacking AfIlv3A and ilv3B exhibit reduced levels of virulence in murine infection models, emphasising the importance of branched-chain amino acid biosynthesis in fungal infections, and hence the potential of targeting this pathway with antifungal agents. Here we propose that AfIlv3A/AFUA_2G2410 be named ilvC.