RESUMO
Eukaryotic striatin forms striatin-interacting phosphatase and kinase (STRIPAK) complexes that control many cellular processes including development, cellular transport, signal transduction, stem cell differentiation and cardiac functions. However, detailed knowledge of complex assembly and its roles in stress responses are currently poorly understood. Here, we discovered six striatin (StrA) interacting proteins (Sips), which form a heptameric complex in the filamentous fungus Aspergillus nidulans. The complex consists of the striatin scaffold StrA, the Mob3-type kinase coactivator SipA, the SIKE-like protein SipB, the STRIP1/2 homolog SipC, the SLMAP-related protein SipD and the catalytic and regulatory phosphatase 2A subunits SipE (PpgA), and SipF, respectively. Single and double deletions of the complex components result in loss of multicellular light-dependent fungal development, secondary metabolite production (e.g. mycotoxin Sterigmatocystin) and reduced stress responses. sipA (Mob3) deletion is epistatic to strA deletion by supressing all the defects caused by the lack of striatin. The STRIPAK complex, which is established during vegetative growth and maintained during the early hours of light and dark development, is mainly formed on the nuclear envelope in the presence of the scaffold StrA. The loss of the scaffold revealed three STRIPAK subcomplexes: (I) SipA only interacts with StrA, (II) SipB-SipD is found as a heterodimer, (III) SipC, SipE and SipF exist as a heterotrimeric complex. The STRIPAK complex is required for proper expression of the heterotrimeric VeA-VelB-LaeA complex which coordinates fungal development and secondary metabolism. Furthermore, the STRIPAK complex modulates two important MAPK pathways by promoting phosphorylation of MpkB and restricting nuclear shuttling of MpkC in the absence of stress conditions. SipB in A. nidulans is similar to human suppressor of IKK-ε(SIKE) protein which supresses antiviral responses in mammals, while velvet family proteins show strong similarity to mammalian proinflammatory NF-KB proteins. The presence of these proteins in A. nidulans further strengthens the hypothesis that mammals and fungi use similar proteins for their immune response and secondary metabolite production, respectively.
Assuntos
Aspergillus nidulans/metabolismo , Proteínas Fúngicas/metabolismo , Aspergillus nidulans/genética , Aspergillus nidulans/crescimento & desenvolvimento , Sequestradores de Radicais Livres/metabolismo , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Deleção de Genes , Genes Fúngicos , Proteínas de Fluorescência Verde/química , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Luz , Sistema de Sinalização das MAP Quinases , Modelos Biológicos , Membrana Nuclear/metabolismo , Estrutura Quaternária de Proteína , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Estresse FisiológicoRESUMO
OBJECTIVE: We investigated R2* relaxation rates as a marker of iron content in the substantia nigra in patients with common tremor disorders and explored their diagnostic properties. METHODS: Mean nigral R2* rates were measured in 40 patients with tremor-dominant Parkinson's disease (PD), 15 with tremor in dystonia, 25 with essential tremor, and 25 healthy controls. RESULTS: Tremor-dominant PD patients had significantly higher nigral R2* values (34.1 ± 5.7) than those with tremor in dystonia (30.0 ± 3.9), essential tremor (30.6 ± 4.8), and controls (30.0 ± 2.8). An R2* threshold of 31.15 separated tremor-dominant PD from controls with a sensitivity and specificity of 67.5% and 72%. The sensitivity and specificity for discrimination between PD and non-PD tremor patients was 67.5% and 60%. CONCLUSION: Iron content in the substantia nigra is significantly higher in tremor-dominant PD than in tremor in dystonia, essential tremor, and controls. Because of the considerable overlap, nigral R2* cannot be suggested as a useful diagnostic tool. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.
Assuntos
Ferro/metabolismo , Substância Negra/metabolismo , Tremor/metabolismo , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/análise , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Doença de Parkinson/diagnóstico , Doença de Parkinson/metabolismo , Substância Negra/fisiopatologia , Tremor/fisiopatologiaRESUMO
Alzheimer's disease (AD) patients show altered patterns of functional connectivity (FC) on resting state functional magnetic resonance imaging (RSfMRI) scans. It is yet unclear which RSfMRI measures are most informative for the individual classification of AD patients. We investigated this using RSfMRI scans from 77 AD patients (MMSE = 20.4 ± 4.5) and 173 controls (MMSE = 27.5 ± 1.8). We calculated i) FC matrices between resting state components as obtained with independent component analysis (ICA), ii) the dynamics of these FC matrices using a sliding window approach, iii) the graph properties (e.g., connection degree, and clustering coefficient) of the FC matrices, and iv) we distinguished five FC states and administered how long each subject resided in each of these five states. Furthermore, for each voxel we calculated v) FC with 10 resting state networks using dual regression, vi) FC with the hippocampus, vii) eigenvector centrality, and viii) the amplitude of low frequency fluctuations (ALFF). These eight measures were used separately as predictors in an elastic net logistic regression, and combined in a group lasso logistic regression model. We calculated the area under the receiver operating characteristic curve plots (AUC) to determine classification performance. The AUC values ranged between 0.51 and 0.84 and the highest were found for the FC matrices (0.82), FC dynamics (0.84) and ALFF (0.82). The combination of all measures resulted in an AUC of 0.85. We show that it is possible to obtain moderate to good AD classification using RSfMRI scans. FC matrices, FC dynamics and ALFF are most discriminative and the combination of all the resting state measures improves classification accuracy slightly.
Assuntos
Doença de Alzheimer/diagnóstico por imagem , Encéfalo/diagnóstico por imagem , Conectoma/métodos , Imageamento por Ressonância Magnética/métodos , Rede Nervosa/diagnóstico por imagem , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/fisiopatologia , Encéfalo/fisiopatologia , Conectoma/classificação , Feminino , Hipocampo/diagnóstico por imagem , Hipocampo/fisiopatologia , Humanos , Imageamento por Ressonância Magnética/classificação , Masculino , Pessoa de Meia-Idade , Rede Nervosa/fisiopatologiaRESUMO
Cell-cell fusion in fungi is required for colony formation, nutrient transfer and signal transduction. Disruption of genes required for hyphal fusion in Epichloë festucae, a mutualistic symbiont of Lolium grasses, severely disrupts the host interaction phenotype. They examined whether symB and symC, the E. festucae homologs of Podospora anserina self-signaling genes IDC2 and IDC3, are required for E. festucae hyphal fusion and host symbiosis. Deletion mutants of these genes were defective in hyphal cell fusion, formed intra-hyphal hyphae, and had enhanced conidiation. SymB-GFP and SymC-mRFP1 localize to plasma membrane, septa and points of hyphal cell fusion. Plants infected with ΔsymB and ΔsymC strains were severely stunted. Hyphae of the mutants colonized vascular bundles, were more abundant than wild type in the intercellular spaces and formed intra-hyphal hyphae. Although these phenotypes are identical to those previously observed for cell wall integrity MAP kinase mutants no difference was observed in the basal level of MpkA phosphorylation or its cellular localization in the mutant backgrounds. Both genes contain binding sites for the transcription factor ProA. Collectively these results show that SymB and SymC are key components of a conserved signaling network for E. festucae to maintain a mutualistic symbiotic interaction within L. perenne.
Assuntos
Epichloe/genética , Proteínas Fúngicas/genética , Hifas/genética , Lolium/crescimento & desenvolvimento , Proteínas de Membrana/genética , Esporos Fúngicos/crescimento & desenvolvimento , Simbiose/genética , Fusão Celular , Epichloe/fisiologia , Proteínas Fúngicas/metabolismo , Regulação Fúngica da Expressão Gênica , Hifas/fisiologia , Lolium/microbiologia , Proteínas de Membrana/metabolismo , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosforilação , Regiões Promotoras Genéticas/genética , Ligação Proteica/genética , Deleção de Sequência/genética , Esporos Fúngicos/genética , Fatores de Transcrição/metabolismoRESUMO
Diffusion magnetic resonance imaging (MRI) is a powerful non-invasive method to study white matter integrity, and is sensitive to detect differences in Alzheimer's disease (AD) patients. Diffusion MRI may be able to contribute towards reliable diagnosis of AD. We used diffusion MRI to classify AD patients (N=77), and controls (N=173). We use different methods to extract information from the diffusion MRI data. First, we use the voxel-wise diffusion tensor measures that have been skeletonised using tract based spatial statistics. Second, we clustered the voxel-wise diffusion measures with independent component analysis (ICA), and extracted the mixing weights. Third, we determined structural connectivity between Harvard Oxford atlas regions with probabilistic tractography, as well as graph measures based on these structural connectivity graphs. Classification performance for voxel-wise measures ranged between an AUC of 0.888, and 0.902. The ICA-clustered measures ranged between an AUC of 0.893, and 0.920. The AUC for the structural connectivity graph was 0.900, while graph measures based upon this graph ranged between an AUC of 0.531, and 0.840. All measures combined with a sparse group lasso resulted in an AUC of 0.896. Overall, fractional anisotropy clustered into ICA components was the best performing measure. These findings may be useful for future incorporation of diffusion MRI into protocols for AD classification, or as a starting point for early detection of AD using diffusion MRI.
Assuntos
Doença de Alzheimer/classificação , Doença de Alzheimer/diagnóstico por imagem , Mapeamento Encefálico/métodos , Imagem de Difusão por Ressonância Magnética , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/patologia , Anisotropia , Imagem de Tensor de Difusão , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Aprendizado de Máquina , Masculino , Pessoa de Meia-Idade , Substância Branca/diagnóstico por imagem , Substância Branca/patologiaRESUMO
Intercellular communication is critical for the survival of unicellular organisms as well as for the development and function of multicellular tissues. Cell-to-cell signaling is also required to develop the interconnected mycelial network characteristic of filamentous fungi and is a prerequisite for symbiotic and pathogenic host colonization achieved by molds. Somatic cell-cell communication and subsequent cell fusion is governed by the MAK-2 mitogen activated protein kinase (MAPK) cascade in the filamentous ascomycete model Neurospora crassa, yet the composition and mode of regulation of the MAK-2 pathway are currently unclear. In order to identify additional components involved in MAK-2 signaling we performed affinity purification experiments coupled to mass spectrometry with strains expressing functional GFP-fusion proteins of the MAPK cascade. This approach identified STE-50 as a regulatory subunit of the Ste11p homolog NRC-1 and HAM-5 as cell-communication-specific scaffold protein of the MAPK cascade. Moreover, we defined a network of proteins consisting of two Ste20-related kinases, the small GTPase RAS-2 and the adenylate cyclase capping protein CAP-1 that function upstream of the MAK-2 pathway and whose signals converge on the NRC-1/STE-50 MAP3K complex and the HAM-5 scaffold. Finally, our data suggest an involvement of the striatin interacting phosphatase and kinase (STRIPAK) complex, the casein kinase 2 heterodimer, the phospholipid flippase modulators YPK-1 and NRC-2 and motor protein-dependent vesicle trafficking in the regulation of MAK-2 pathway activity and function. Taken together, these data will have significant implications for our mechanistic understanding of MAPK signaling and for homotypic cell-cell communication in fungi and higher eukaryotes.
Assuntos
Proteínas Fúngicas/genética , Quinases de Proteína Quinase Ativadas por Mitógeno/genética , Proteínas Quinases/genética , Proteínas Serina-Treonina Quinases/genética , Proteínas ras/genética , Comunicação Celular/genética , Membrana Celular/genética , Membrana Celular/metabolismo , Proteínas Fúngicas/metabolismo , Histidina Quinase , Sistema de Sinalização das MAP Quinases/genética , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Neurospora crassa/genética , Neurospora crassa/metabolismo , Fosforilação , Proteínas Quinases/metabolismo , Proteínas ras/metabolismoRESUMO
Nuclear DBF2p-related (NDR) kinases constitute a functionally conserved protein family of eukaryotic regulators that control cell division and polarity. In fungi, they function as effector kinases of the morphogenesis (MOR) and septation initiation (SIN) networks and are activated by pathway-specific germinal centre (GC) kinases. We characterized a third GC kinase, MST-1, that connects both kinase cascades. Genetic and biochemical interactions with SIN components and life cell imaging identify MST-1 as SIN-associated kinase that functions in parallel with the GC kinase SID-1 to activate the SIN-effector kinase DBF-2. SID-1 and MST-1 are both regulated by the upstream SIN kinase CDC-7, yet in an opposite manner. Aberrant cortical actomyosin rings are formed in Δmst-1, which resulted in mis-positioned septa and irregular spirals, indicating that MST-1-dependent regulation of the SIN is required for proper formation and constriction of the septal actomyosin ring. However, MST-1 also interacts with several components of the MOR network and modulates MOR activity at multiple levels. MST-1 functions as promiscuous enzyme and also activates the MOR effector kinase COT-1 through hydrophobic motif phosphorylation. In addition, MST-1 physically interacts with the MOR kinase POD-6, and dimerization of both proteins inactivates the GC kinase hetero-complex. These data specify an antagonistic relationship between the SIN and MOR during septum formation in the filamentous ascomycete model Neurospora crassa that is, at least in part, coordinated through the GC kinase MST-1. The similarity of the SIN and MOR pathways to the animal Hippo and Ndr pathways, respectively, suggests that intensive cross-communication between distinct NDR kinase modules may also be relevant for the homologous NDR kinases of higher eukaryotes.
Assuntos
Actinas/genética , Morfogênese/genética , Proteínas Serina-Treonina Quinases/genética , Transdução de Sinais/genética , Actomiosina/genética , Proteínas de Ciclo Celular/genética , Divisão Celular , Proteínas Fúngicas/genética , Quinases do Centro Germinativo , Proteínas de Membrana Transportadoras/genética , Neurospora crassa/genética , Fosforilação/genéticaRESUMO
The striatin interacting phosphatase and kinase (STRIPAK) complex, which is composed of striatin, protein phosphatase PP2A and kinases, is required for fruiting-body development and cell fusion in the filamentous ascomycete Sordaria macrospora. Here, we report on the interplay of the glycosylphosphatidylinositol (GPI)-anchored protein SmGPI1 with the kinase activator SmMOB3, a core component of human and fungal STRIPAK complexes. SmGPI1 is conserved among filamentous ascomycetes and was first identified in a yeast two-hybrid screen using SmMOB3 as bait. The physical interaction of SmMOB3 and SmGPI1 was verified by co-immunoprecipitation. In vivo localization and differential centrifugation revealed that SmGPI1 is predominantly secreted and attached to the cell wall but is also associated with mitochondria and appears to be a dual-targeted protein. Deletion of Smgpi1 led to an increased number of fruiting bodies that were normally shaped but reduced in size. In addition, Smmob3 and Smgpi1 genetically interact. In the sterile ΔSmmob3 background deletion of Smgpi1 restores fertility, vegetative growth as well as hyphal-fusion defects. The suppression effect was specific for the ΔSmmob3 mutant as deletion of Smgpi1 in other STRIPAK mutants does not restore fertility.
Assuntos
Ascomicetos/genética , Glicosilfosfatidilinositóis/genética , Monoéster Fosfórico Hidrolases/metabolismo , Sordariales/genética , Sequência de Aminoácidos , Ascomicetos/metabolismo , Carpóforos/genética , Carpóforos/metabolismo , Deleção de Genes , Glicosilfosfatidilinositóis/metabolismo , Hifas/metabolismo , Imunoprecipitação , Dados de Sequência Molecular , Mutação , Proteína Fosfatase 2/metabolismo , Sordariales/enzimologia , Sordariales/metabolismoRESUMO
BACKGROUND: In a small group of patients, we have previously shown that a combination of electrophysiological tests was able to distinguish functional (psychogenic) tremor and organic tremor with excellent sensitivity and specificity. OBJECTIVES: This study aims to validate an electrophysiological test battery as a tool to diagnose patients with functional tremor with a "laboratory-supported" level of certainty. METHODS: For this prospective data collection study, we recruited 38 new patients with functional tremor (mean age 37.9 ± 24.5 years; mean disease duration 5.9 ± 9.0 years) and 73 new patients with organic tremor (mean age 55.4 ± 25.4 years; mean disease duration 15.8 ± 17.7 years). Tremor was recorded at rest, posture (with and without loading), action, while performing tapping tasks (1, 3, and 5 Hz), and while performing ballistic movements with the less-affected hand. Electrophysiological tests were performed by raters blinded to the clinical diagnosis. We calculated a sum score for all performed tests (maximum of 10 points) and used a previously suggested cut-off score of 3 points for a diagnosis of laboratory-supported functional tremor. RESULTS: We demonstrated good interrater reliability and test-retest reliability. Patients with functional tremor had a higher average score on the test battery when compared with patients with organic tremor (3.6 ± 1.4 points vs 1.0 ± 0.8 points; P < .001), and the predefined cut-off score for laboratory-supported functional tremor yielded a test sensitivity of 89.5% and a specificity of 95.9%. CONCLUSION: We now propose this test battery as the basis of laboratory-supported criteria for the diagnosis of functional tremor, and we encourage its use in clinical and research practice.
Assuntos
Acelerometria/métodos , Eletromiografia/métodos , Exame Neurológico/métodos , Transtornos Psicofisiológicos/diagnóstico , Tremor/diagnóstico , Acelerometria/normas , Adulto , Idoso , Eletromiografia/normas , Medicina Baseada em Evidências , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Exame Neurológico/normas , Transtornos Psicofisiológicos/fisiopatologia , Reprodutibilidade dos Testes , Método Simples-Cego , Tremor/fisiopatologiaRESUMO
We analyzed the relation of several synchrony markers in the electroencephalogram (EEG) and Alzheimer's disease (AD) severity as measured by Mini-Mental State Examination (MMSE) scores. The study sample consisted of 79 subjects diagnosed with probable AD. All subjects were participants in the PRODEM-Austria study. Following a homogeneous protocol, the EEG was recorded both in resting state and during a cognitive task. We employed quadratic least squares regression to describe the relation between MMSE and the EEG markers. Factor analysis was used for estimating a potentially lower number of unobserved synchrony factors. These common factors were then related to MMSE scores as well. Most markers displayed an initial increase of EEG synchrony with MMSE scores from 26 to 21 or 20, and a decrease below. This effect was most prominent during the cognitive task and may be owed to cerebral compensatory mechanisms. Factor analysis provided interesting insights in the synchrony structures and the first common factors were related to MMSE scores with coefficients of determination up to 0.433. We conclude that several of the proposed EEG markers are related to AD severity for the overall sample with a wide dispersion for individual subjects. Part of these fluctuations may be owed to fluctuations and day-to-day variability associated with MMSE measurements. Our study provides a systematic analysis of EEG synchrony based on a large and homogeneous sample. The results indicate that the individual markers capture different aspects of EEG synchrony and may reflect cerebral compensatory mechanisms in the early stages of AD.
Assuntos
Doença de Alzheimer/fisiopatologia , Encéfalo/fisiopatologia , Sincronização Cortical/fisiologia , Idoso , Idoso de 80 Anos ou mais , Eletroencefalografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Processamento de Sinais Assistido por ComputadorRESUMO
Choice in public services is controversial. We exploit a reform in the English National Health Service to assess the effect of removing constraints on patient choice. We estimate a demand model that explicitly captures the removal of the choice constraints imposed on patients. We find that, post-removal, patients became more responsive to clinical quality. This led to a modest reduction in mortality and a substantial increase in patient welfare. The elasticity of demand faced by hospitals increased substantially post- reform and we find evidence that hospitals responded to the enhanced incentives by improving quality. This suggests greater choice can raise quality.
Assuntos
Comportamento de Escolha , Comportamento do Consumidor , Reforma dos Serviços de Saúde , Preferência do Paciente , Medicina Estatal , Ponte de Artéria Coronária/economia , Ponte de Artéria Coronária/mortalidade , Reforma dos Serviços de Saúde/economia , Humanos , Preferência do Paciente/economia , Padrões de Prática Médica , Qualidade da Assistência à Saúde , Taxa de Sobrevida , Reino UnidoRESUMO
Cell communication is essential for eukaryotic development, but our knowledge of molecules and mechanisms required for intercellular communication is fragmentary. In particular, the connection between signal sensing and regulation of cell polarity is poorly understood. In the filamentous ascomycete Neurospora crassa, germinating spores mutually attract each other and subsequently fuse. During these tropic interactions, the two communicating cells rapidly alternate between two different physiological states, probably associated with signal delivery and response. The MAK2 MAP kinase cascade mediates cell-cell signaling. Here, we show that the conserved scaffolding protein HYM1/MO25 controls the cell shape-regulating NDR kinase module as well as the signal-receiving MAP kinase cascade. HYM1 functions as an integral part of the COT1 NDR kinase complex to regulate the interaction with its upstream kinase POD6 and thereby COT1 activity. In addition, HYM1 interacts with NRC1, MEK2, and MAK2, the three kinases of the MAK2 MAP kinase cascade, and co-localizes with MAK2 at the apex of growing cells. During cell fusion, the three kinases of the MAP kinase module as well as HYM1 are recruited to the point of cell-cell contact. hym-1 mutants phenocopy all defects observed for MAK2 pathway mutants by abolishing MAK2 activity. An NRC1-MEK2 fusion protein reconstitutes MAK2 signaling in hym-1, while constitutive activation of NRC1 and MEK2 does not. These data identify HYM1 as a novel regulator of the NRC1-MEK2-MAK2 pathway, which may coordinate NDR and MAP kinase signaling during cell polarity and intercellular communication.
Assuntos
Proteínas de Transporte/genética , Comunicação Celular/genética , Neurospora crassa , Proteínas Quinases , Proteínas Serina-Treonina Quinases/genética , Esporos , Sequência de Aminoácidos , Proteínas de Transporte de Cátions/metabolismo , Comunicação Celular/fisiologia , Proteínas de Ciclo Celular/metabolismo , Polaridade Celular , Forma Celular , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Histidina Quinase , Sistema de Sinalização das MAP Quinases , Neurospora crassa/genética , Neurospora crassa/metabolismo , Fosforilação , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Serina-Treonina Quinases/fisiologia , Esporos/genética , Esporos/crescimento & desenvolvimento , Esporos/metabolismoRESUMO
BACKGROUND AND PURPOSE: NINDS (National Institute of Neurological Disorders and Stroke)-SiGN (Stroke Genetics Network) is an international consortium of ischemic stroke studies that aims to generate high-quality phenotype data to identify the genetic basis of pathogenic stroke subtypes. This analysis characterizes the etiopathogenetic basis of ischemic stroke and reliability of stroke classification in the consortium. METHODS: Fifty-two trained and certified adjudicators determined both phenotypic (abnormal test findings categorized in major pathogenic groups without weighting toward the most likely cause) and causative ischemic stroke subtypes in 16 954 subjects with imaging-confirmed ischemic stroke from 12 US studies and 11 studies from 8 European countries using the web-based Causative Classification of Stroke System. Classification reliability was assessed with blinded readjudication of 1509 randomly selected cases. RESULTS: The distribution of pathogenic categories varied by study, age, sex, and race (P<0.001 for each). Overall, only 40% to 54% of cases with a given major ischemic stroke pathogenesis (phenotypic subtype) were classified into the same final causative category with high confidence. There was good agreement for both causative (κ 0.72; 95% confidence interval, 0.69-0.75) and phenotypic classifications (κ 0.73; 95% confidence interval, 0.70-0.75). CONCLUSIONS: This study demonstrates that pathogenic subtypes can be determined with good reliability in studies that include investigators with different expertise and background, institutions with different stroke evaluation protocols and geographic location, and patient populations with different epidemiological characteristics. The discordance between phenotypic and causative stroke subtypes highlights the fact that the presence of an abnormality in a patient with stroke does not necessarily mean that it is the cause of stroke.
Assuntos
Acidente Vascular Cerebral/classificação , Acidente Vascular Cerebral/etiologia , Acidente Vascular Cerebral/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , National Institute of Neurological Disorders and Stroke (USA) , Fenótipo , Estados UnidosRESUMO
Intercellular communication and somatic cell fusion are important for fungal colony establishment, multicellular differentiation and have been associated with host colonization and virulence of pathogenic species. By a combination of genetic, biochemical and live cell imaging techniques, we characterized the Neurospora crassaâ STRIPAK complex that is essential for self-signalling and consists of the six proteins HAM-2/STRIP, HAM-3/striatin, HAM-4/SLMAP, MOB-3/phocein, PPG-1/PP2A-C and PP2A-A. We describe that the core STRIPAK components HAM-2 and HAM-3 are central for the assembly of the complex at the nuclear envelope, while the phosphatase PPG-1 only transiently associates with this central subcomplex. Our data connect the STRIPAK complex with two MAP kinase pathways: (i) nuclear accumulation of the cell wall integrity MAP kinase MAK-1 depends on the functional integrity of the STRIPAK complex at the nuclear envelope, and (ii) phosphorylation of MOB-3 by the MAP kinase MAK-2 impacts the nuclear accumulation of MAK-1. In summary, these data support a model, in which MAK-2-dependent phosphorylation of MOB-3 is part of a MAK-1 import mechanism. Although self-communication remained intact in the absence of nuclear MAK-1 accumulation, supporting the presence of multiple mechanisms that co-ordinate robust intercellular communication, proper fruiting body morphology was dependent on the MAK-2-phosphorylated N-terminus of MOB-3.
Assuntos
Núcleo Celular/metabolismo , Proteínas Fúngicas/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Neurospora crassa/metabolismo , Membrana Nuclear/metabolismo , Transporte Ativo do Núcleo Celular , Núcleo Celular/genética , Parede Celular/metabolismo , Regulação Fúngica da Expressão Gênica , Sistema de Sinalização das MAP Quinases , Mutagênese , Neurospora crassa/genética , Fenótipo , FosforilaçãoRESUMO
White matter hyperintensities and lacunes are among the most frequent abnormalities on brain magnetic resonance imaging. They are commonly related to cerebral small vessel disease and associated with both stroke and dementia. We examined the spatial relationships between incident lacunes and white matter hyperintensities and related these findings to information on vascular anatomy to study possible mechanistic links between the two lesion types. Two hundred and seventy-six patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a genetically defined small vessel disease with mutations in the NOTCH3 gene were followed with magnetic resonance imaging over a total of 633 patient years. Using difference images and Jacobian maps from registered images we identified 104 incident lacunes. The majority (n = 95; 91.3%) of lacunes developed at the edge of a white matter hyperintensity whereas few lacunes were found to develop fully within (n = 6; 5.8%) or outside (n = 3; 2.9%) white matter hyperintensities. Adding information on vascular anatomy revealed that the majority of incident lacunes developed proximal to a white matter hyperintensity along the course of perforating vessels supplying the respective brain region. We further studied the spatial relationship between prevalent lacunes and white matter hyperintensities both in 365 patients with CADASIL and in 588 elderly subjects from the Austrian Stroke Prevention Study. The results were consistent with the results for incident lacunes. Lesion prevalence maps in different disease stages showed a spread of lesions towards subcortical regions in both cohorts. Our findings suggest that the mechanisms of lacunes and white matter hyperintensities are intimately connected and identify the edge of white matter hyperintensities as a predilection site for lacunes. Our observations further support and refine the concept of the white matter hyperintensity penumbra.
Assuntos
CADASIL/complicações , Leucoencefalopatias/epidemiologia , Leucoencefalopatias/etiologia , Acidente Vascular Cerebral Lacunar/epidemiologia , Acidente Vascular Cerebral Lacunar/etiologia , Adulto , Idoso , CADASIL/epidemiologia , Estudos de Coortes , Progressão da Doença , Feminino , Humanos , Leucoencefalopatias/genética , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Fibras Nervosas Mielinizadas/patologia , Receptor Notch3 , Receptores Notch/genética , Acidente Vascular Cerebral Lacunar/patologia , Adulto JovemRESUMO
BACKGROUND: Recent small subcortical infarcts (RSSI) are the neuroimaging hallmark feature of small vessel disease (SVD)-related acute lacunar stroke. Long-term data on recurrent cerebrovascular events including their aetiology after RSSI are scarce. PATIENTS AND METHODS: This retrospective study included all consecutive ischaemic stroke patients with an MRI-confirmed RSSI (in the supply area of a small single brain artery) at University Hospital Graz between 2008 and 2013. We investigated associations between clinical and SVD features on MRI (STRIVE criteria) and recurrent cerebrovascular events, using multivariable Cox regression adjusted for age, sex, vascular risk factors and MRI parameters. RESULTS: We analysed 332 consecutive patients (mean age 68 years, 36% women; median follow-up time 12 years). A recurrent ischaemic cerebrovascular event occurred in 70 patients (21.1%; 54 ischaemic strokes, 22 transient ischaemic attacks) and was mainly attributed to SVD (68%). 26 patients (7.8%) developed intracranial haemorrhage. In multivariable analysis, diabetes (HR 2.43, 95% CI 1.44-3.88), severe white matter hyperintensities (HR 1.97, 95% CI 1.14-3.41), and cerebral microbleeds (HR 1.89, 95% CI 1.32-3.14) on baseline MRI were related to recurrent ischaemic stroke/TIA, while presence of cerebral microbleeds increased the risk for intracranial haemorrhage (HR 3.25, 95% CI 1.39-7.59). A widely used SVD summary score indicated high risks of recurrent ischaemic (HR 1.22, 95% CI 1.01-1.49) and haemorrhagic cerebrovascular events (HR 1.57, 95% CI 1.11-2.22). CONCLUSION: Patients with RSSI have a substantial risk for recurrent cerebrovascular events-particularly those with coexisting chronic SVD features. Recurrent events are mainly related to SVD again.
Assuntos
Imageamento por Ressonância Magnética , Recidiva , Humanos , Feminino , Masculino , Idoso , Estudos Retrospectivos , Pessoa de Meia-Idade , Fatores de Risco , Doenças de Pequenos Vasos Cerebrais/diagnóstico por imagem , Doenças de Pequenos Vasos Cerebrais/epidemiologia , Doenças de Pequenos Vasos Cerebrais/complicações , Seguimentos , Idoso de 80 Anos ou mais , Infarto Cerebral/diagnóstico por imagem , Infarto Cerebral/etiologia , Infarto Cerebral/epidemiologia , AVC Isquêmico/diagnóstico por imagem , AVC Isquêmico/complicações , AVC Isquêmico/etiologia , AVC Isquêmico/epidemiologiaRESUMO
Background: Cardiovascular disease (CVD) risk factors are highly prevalent among Hispanic/Latino adults, while the prevalence of MRI infarcts is not well-documented. We, therefore, sought to examine the relationships between CVD risk factors and infarcts with brain structure among Hispanic/Latino individuals. Methods: Participants included 1,886 Hispanic/Latino adults (50-85 years) who underwent magnetic resonance imaging (MRI) as part of the Study of Latinos-Investigation of Neurocognitive Aging-MRI (SOL-INCA-MRI) study. CVD risk was measured approximately 10.5 years before MRI using the Framingham cardiovascular risk score, a measure of 10-year CVD risk (low (<10%), medium (10- < 20%), and high (≥20%)). MR infarcts were determined as present or absent. Outcomes included total brain, cerebral and lobar cortical gray matter, hippocampal, lateral ventricle, and total white matter hyperintensity (WMH) volumes. Linear regression models tested associations between CVD risk and infarct with MRI outcomes and for modifications by age and sex. Results: Sixty percent of participants were at medium or high CVD risk. Medium and high CVD risk were associated with lower total brain and frontal gray matter and higher WMH volumes compared to those with low CVD risk. High CVD risk was additionally associated with lower total cortical gray matter and parietal volumes and larger lateral ventricle volumes. Men tended to have greater CVDRF-related differences in total brain volumes than women. The association of CVD risk factors on total brain volumes increased with age, equal to an approximate 7-year increase in total brain aging among the high-CVD-risk group compared to the low-risk group. The presence of infarct(s) was associated with lower total brain volumes, which was equal to an approximate 5-year increase in brain aging compared to individuals without infarcts. Infarcts were also associated with smaller total cortical gray matter, frontal and parietal volumes, and larger lateral ventricle and WMH volumes. Conclusion: The high prevalence of CVD risk among Hispanic/Latino adults may be associated with accelerated brain aging.
RESUMO
Rho proteins are key regulators of cellular morphogenesis, but their function in filamentous fungi is poorly understood. By generating conditional rho-1 mutants, we dissected the function of the essential GTPase RHO1 in cell polarization and maintenance of cell wall integrity in Neurospora crassa. We identified NCU00668/RGF1 as RHO1-specific exchange factor, which controls actin organization and the cell wall integrity MAK1 MAP kinase pathway through the direct interaction of active RHO1 with the formin BNI1 and PKC1 respectively. The activity of RGF1 is controlled by an intramolecular interaction of its DEP and GEF domains that blocks the activation of the GTPase. Moreover, the N-terminal region including the DEP domain of RGF1 interacts with the plasma membrane sensor NCU06910/WSC1, potentially to activate the cell wall integrity pathway. RHO1 also functions as regulatory subunit of the glucan synthase. N. crassa possesses a second GTPase, RHO2, that is highly homologous to RHO1. RHO2 is of minor importance for growth and does not interact with BNI1. Conditional rho-1;rho-2 double mutants display strong synthetic growth and cell polarity defects. We show that RHO2 does not regulate glucan synthase activity and the actin cytoskeleton, but physically interacts with PKC1 to regulate the cell wall integrity pathway.
Assuntos
Parede Celular/metabolismo , Proteínas Fúngicas/metabolismo , Hifas/fisiologia , Neurospora crassa/enzimologia , Neurospora crassa/fisiologia , Proteínas rho de Ligação ao GTP/metabolismo , Sequência de Aminoácidos , Deleção de Genes , Genes Essenciais , Modelos Biológicos , Dados de Sequência Molecular , Neurospora crassa/crescimento & desenvolvimento , Mapeamento de Interação de Proteínas , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Proteínas rho de Ligação ao GTP/genéticaRESUMO
Sexual development in fungi is a complex process involving the generation of new cell types and tissues - an essential step for all eukaryotic life. The characterization of sterile mutants in the ascomycete Sordaria macrospora has led to a number of proteins involved in sexual development, but a link between these proteins is still missing. Using a combined tandem-affinity purification/mass spectrometry approach, we showed in vivo association of developmental protein PRO22 with PRO11, homologue of mammalian striatin, and SmPP2AA, scaffolding subunit of protein phosphatase 2A. Further experiments extended the protein network to the putative kinase activator SmMOB3, known to be involved in sexual development. Extensive yeast two-hybrid studies allowed us to pinpoint functional domains involved in protein-protein interaction. We show for the first time that a number of already known factors together with new components associate in vivo to form a highly conserved multi-subunit complex. Strikingly, a similar complex has been described in humans, but the function of this so-called striatin interacting phosphatase and kinase (STRIPAK) complex is largely unknown. In S. macrospora, truncation of PRO11 and PRO22 leads to distinct defects in sexual development and cell fusion, indicating a role for the fungal STRIPAK complex in both processes.
Assuntos
Proteínas Fúngicas/metabolismo , Multimerização Proteica , Sordariales/crescimento & desenvolvimento , Cromatografia de Afinidade , Proteínas Fúngicas/química , Proteínas Fúngicas/isolamento & purificação , Espectrometria de Massas , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Mapeamento de Interação de Proteínas , Técnicas do Sistema de Duplo-HíbridoRESUMO
Bradykinesia-the cardinal symptom in Parkinson's disease (PD)-affects both upper and lower limbs. While several functional imaging studies investigated the impact of levodopa on movement-related neural activity in Parkinson's disease during upper limb movements, analogue studies on lower limb movements are rare. We studied 20 patients with PD (mean age 66.8 ± 7.2 years) after at least 12 h drug withdrawal (OFF-state) and a second time approximately 40 min after oral administration of 200 mg levodopa (ON-state) behaviourally and by functional magnetic resonance imaging (fMRI) at 3 T during externally cued active ankle movements of the more affected foot at fixed rate. Results were compared with that obtained in ten healthy controls (HC) to separate pure pharmacological from disease-related levodopa-induced effects and to allow for interaction analyses. Behaviourally, all patients improved by at least 20 % regarding the motor score of the Unified Parkinson's disease rating scale after levodopa-challenge (mean scores OFF-state: 38.4 ± 10.1; ON-state: 25.5 ± 8.1). On fMRI, levodopa application elicited increased activity in subcortical structures (contralateral putamen and thalamus) in the patients. In contrast, no significant levodopa-induced activation changes were found in HC. The interaction between "PD/HC group factor" and "levodopa OFF/ON" did not show significant results. Given the levodopa-induced activation increases in the putamen and thalamus with unilateral ankle movements in patients with PD but not in HC, we speculate that these regions show the most prominent response to levodopa within the cortico-subcortical motor-circuit in the context of nigrostriatal dysfunction.