17,229 research outputs found

    Investigating neural differentiation capacity in AlzheimerÔÇÖs disease iPSC-derived neural stem cells

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    Neurodegeneration in AlzheimerÔÇÖs disease (AD) may be exacerbated by dysregulated hippocampal neurogenesis. Neural stem cells (NSC) maintain adult neurogenesis and depletion of the NSC niche has been associated with age-related cognitive decline and dementia. We hypothesise that familial AD (FAD) mutations bias NSC toward premature neural specification, reducing the stem cell niche over time and accelerating disease progression. Somatic cells derived from patients with FAD (PSEN1 A246E and PSEN1 M146L heterozygous mutations) and healthy controls were reprogrammed to generate induced pluripotent stem cells (iPSC). Pluripotency for patient and control iPSC lines was confirmed, then cells were amplified and cryopreserved as stores. iPSC were subjected to neural specification to rosette-forming SOX2+/nestin+ NSCs for comparative evaluations between FAD and age-matched controls. FAD patient and control NSC were passaged under defined steady state culture conditions to assess stem cell maintenance using quantitative molecular markers (SOX2, nestin, NeuN, MAP2 and ╬▓III-tubulin). We observed trends towards downregulated expression of the nestin coding gene NES (p=0.051) and upregulated expression of MAP2 (p=0.16) in PSEN1 NSC compared with control NSC, indicative of a premature differentiation phenotype induced by presence of the PSEN1 mutation. Cell cycle analysis of PSEN1 NSC showed that compared with controls, a greater number of PSEN1 NSC were retained in G0/G1 phase of the cell cycle (p=0.39), fewer progressed to S-phase (p=0.11) and fewer still reached G2 phase (p=0.23), suggesting cell cycle progression may be impaired in PSEN1 NSC. Nuclear DNA fragmentation was increased (p=0.10) in FAD NSC compared with controls, indicative of elevated cell death/apoptosis. Flow cytometry-based analysis of live, nestin+ NSC and NPC indicated increased apoptosis (p=0.14) in FAD NSC compared with controls, as well as increasing levels of apoptosis (p=0.33) in FAD NSC as they specified to neural progenitor cells. Global RNA sequencing was used to identify transcriptomic changes occurring during both disease and control neural specification. GO analysis of DEGs between PSEN1 and control NSC at P3 revealed significant upregulation (FDR<0.0000259) of 5 biological processes related to transcription and gene expression as well as significant upregulation (FDR<0.000000725) of 12 molecular functions related to DNA binding and transcription factor activity. These data suggest significant changes in gene expression were occurring in PSEN1 NSC at P3 compared with control NSC at the same stage in neural specification. The number of DEGs (p<0.05) between PSEN1 and control NSC at P3 was 9.92-fold higher than the number of DEGs between PSEN1 and control NSC at P2, suggesting transcriptomic differences between PSEN1 and control NSC become more pronounced as cells specify further down the neural lineage. Gene ontology (GO) analysis of differentially expressed genes (DEGs) specific to AD neural differentiation revealed significant dysregulation (FDR p<0.05) of genes related to neurogenesis, apoptosis, cell cycle, transcriptional control, and cell growth/maintenance as PSEN1 NSC matured from P2 to P3. The number of DEGs (p<0.05) in PSEN1 neural differentiation was 4.7-fold higher than the number of DEGs seen in control neural differentiation, indicating more transcriptional changes occurred in PSEN1 NSC than in controls at the same time point in neural specification. Dysregulation of Notch signalling was specific to PSEN1 neural differentiation and Notch related DEGs significantly upregulated (p<0.05) in PSEN1 NSC at P3 compared with P2 included NCOR2, JAG2, CHAC1 and RFNG. qPCR based validation displayed significant upregulation of RFNG (p=0.04) in PSEN1 NSC at P3 compared with PSEN1 NSC at P2, and indicated a trend towards upregulation of JAG2 expression, correlating with RNA sequencing data. Data generated in this study indicate that presence of the PSEN1 mutation significantly increases the number of transcriptional changes occurring during neural differentiation. It is plausible that transcriptional changes to Notch signalling cause dysregulated neural specification and increased apoptosis in PSEN1 NSC, ultimately resulting in depletion of the NSC niche

    Novel insights into Parkin-mediated mitochondrial dysfunction and neuroinflammation in Parkinson's disease

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    Mutations in PRKN cause the second most common genetic form of Parkinson's disease (PD)ÔÇöa debilitating movement disorder that is on the rise due to population aging in the industrial world. PRKN codes for an E3 ubiquitin ligase that has been well established as a key regulator of mitophagy. Together with PTEN-induced kinase 1 (PINK1), Parkin controls the lysosomal degradation of depolarized mitochondria. But Parkin's functions go well beyond mitochondrial clearance: the versatile protein is involved in mitochondria-derived vesicle formation, cellular metabolism, calcium homeostasis, mitochondrial DNA maintenance, mitochondrial biogenesis, and apoptosis induction. Moreover, Parkin can act as a modulator of different inflammatory pathways. In the current review, we summarize the latest literature concerning the diverse roles of Parkin in maintaining a healthy mitochondrial pool. Moreover, we discuss how these recent discoveries may translate into personalized therapeutic approaches not only for PRKN-PD patients but also for a subset of idiopathic cases

    Complement mediated synapse elimination in schizophrenia

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    Schizophrenia (SCZ) is a devastating psychiatric disorder with a typically age of onset in late adolescence. The heritability is estimated to be in between 60-80% and large-scale genome-wide studies have revealed a prominent polygenic component to SCZ risk and identified more than three-hundred common risk variants. Despite a better understanding of which genetic risk variants that increases SCZ risk, it has been challenging to map out the pathophysiology of the disorder. This has stalled the development of target drugs and current treatment options display moderate efficacy and are prone to produce side-effects. SCZ is generally considered a neurodevelopmental disorder and it was proposed more than forty years ago that physiological removal of less active synapses in adolescence, i.e., synaptic pruning, is increased in SCZ and hereby causes the core symptoms of the disorder. This theory has then been supported by post-mortem brain tissue and imaging studies displaying decreased synapse density in SCZ. More recently, it was then shown that the most strongly associated risk loci can largely be explained by copy numbers of a gene coding for the complement factor 4A (C4A). As microglia prune synapses with the help of complement signalling, we therefore decided to use a recently developed human 2D in vitro assay to assess microglial uptake of synaptic structures in models based on cells from individuals with SCZ and healthy controls (study I). We observed excessive uptake of synaptic structures in SCZ models and by mixing synapses from healthy controls with microglia from SCZ patients, and vice versa, we showed the contribution of microglial and neuronal factors contributing to this excessive uptake of synaptic structures. We then developed an in vitro assay to study neuronal complement deposition dependent on copy numbers of C4A in the neuronal lines. Complement 3 (C3) deposition increased by C4A copy numbers but was independent of C4B copy numbers (also unrelated to SCZ risk). Similar C4A copy numbers correlated with the extent of microglial uptake of synapses. Microglial uptake of synaptic structures could also be inhibited by the tetracycline minocycline that also decreased risk of developing SCZ in an electronic health record cohort. In study II, we cerebrospinal fluid (CSF) from first-episode psychosis patients to measure protein levels of C4A. In two independent cohorts, we observed elevated C4A levels (although not C4B levels) in first-episode patients that later were to develop SCZ and could show correlations with markers of synapse density. However, elevated C4A levels could not fully be explained by more copy numbers of C4A in individuals with SCZ and in vitro experiments revealed that SCZ-associated cytokines can induce C4A mRNA expression while also correlating with C4A in patient-derived CSF. In study III, we set-up a 3D brain organoid models to more fully comprehensively capture processes in the developing human brain and then also included innately developing microglia. We display synaptic pruning within these models and use single cell RNA sequencing to validate them. In conclusion, this thesis uses patient-derived cellular modelling to uncover a disease mechanism in SCZ that link genetic risk variants with bona fide protein changes in living patients

    Examples of works to practice staccato technique in clarinet instrument

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    Klarnetin staccato tekni─čini g├╝├žlendirme a┼čamalar─▒ eser ├žal─▒┼čmalar─▒yla uygulanm─▒┼čt─▒r. Staccato ge├ži┼člerini h─▒zland─▒racak ritim ve n├╝ans ├žal─▒┼čmalar─▒na yer verilmi┼čtir. ├çal─▒┼čman─▒n en ├Ânemli amac─▒ sadece staccato ├žal─▒┼čmas─▒ de─čil parmak-dilin e┼č zamanl─▒ uyumunun hassasiyeti ├╝zerinde de durulmas─▒d─▒r. Staccato ├žal─▒┼čmalar─▒n─▒ daha verimli hale getirmek i├žin eser ├žal─▒┼čmas─▒n─▒n i├žinde et├╝t ├žal─▒┼čmas─▒na da yer verilmi┼čtir. ├çal─▒┼čmalar─▒n ├╝zerinde titizlikle durulmas─▒ staccato ├žal─▒┼čmas─▒n─▒n ilham verici etkisi ile m├╝zikal kimli─če yeni bir boyut kazand─▒rm─▒┼čt─▒r. Sekiz ├Âzg├╝n eser ├žal─▒┼čmas─▒n─▒n her a┼čamas─▒ anlat─▒lm─▒┼čt─▒r. Her a┼čaman─▒n bir sonraki performans ve tekni─či g├╝├žlendirmesi esas al─▒nm─▒┼čt─▒r. Bu ├žal─▒┼čmada staccato tekni─činin hangi alanlarda kullan─▒ld─▒─č─▒, nas─▒l sonu├žlar elde edildi─či bilgisine yer verilmi┼čtir. Notalar─▒n parmak ve dil uyumu ile nas─▒l ┼čekillenece─či ve nas─▒l bir ├žal─▒┼čma disiplini i├žinde ger├žekle┼čece─či planlanm─▒┼čt─▒r. Kam─▒┼č-nota-diyafram-parmak-dil-n├╝ans ve disiplin kavramlar─▒n─▒n staccato tekni─činde ayr─▒lmaz bir b├╝t├╝n oldu─ču saptanm─▒┼čt─▒r. Ara┼čt─▒rmada literat├╝r taramas─▒ yap─▒larak staccato ile ilgili ├žal─▒┼čmalar taranm─▒┼čt─▒r. Tarama sonucunda klarnet tekni─čin de kullan─▒lan staccato eser ├žal─▒┼čmas─▒n─▒n az oldu─ču tespit edilmi┼čtir. Metot taramas─▒nda da et├╝t ├žal─▒┼čmas─▒n─▒n daha ├žok oldu─ču saptanm─▒┼čt─▒r. B├Âylelikle klarnetin staccato tekni─čini h─▒zland─▒rma ve g├╝├žlendirme ├žal─▒┼čmalar─▒ sunulmu┼čtur. Staccato et├╝t ├žal─▒┼čmalar─▒ yap─▒l─▒rken, araya eser ├žal─▒┼čmas─▒n─▒n girmesi beyni rahatlatt─▒─č─▒ ve isteklili─či daha artt─▒rd─▒─č─▒ g├Âzlemlenmi┼čtir. Staccato ├žal─▒┼čmas─▒n─▒ yaparken do─čru bir kam─▒┼č se├žimi ├╝zerinde de durulmu┼čtur. Staccato tekni─čini do─čru ├žal─▒┼čmak i├žin do─čru bir kam─▒┼č─▒n dil h─▒z─▒n─▒ artt─▒rd─▒─č─▒ saptanm─▒┼čt─▒r. Do─čru bir kam─▒┼č se├žimi kam─▒┼čtan rahat ses ├ž─▒kmas─▒na ba─čl─▒d─▒r. Kam─▒┼č, dil atma g├╝c├╝n├╝ vermiyorsa daha do─čru bir kam─▒┼č se├žiminin yap─▒lmas─▒ gereklili─či vurgulanm─▒┼čt─▒r. Staccato ├žal─▒┼čmalar─▒nda ba┼čtan sona bir eseri yorumlamak zor olabilir. Bu a├ž─▒dan ├žal─▒┼čma, verilen m├╝zikal n├╝anslara uyman─▒n, dil at─▒┼č performans─▒n─▒ rahatlatt─▒─č─▒n─▒ ortaya koymu┼čtur. Gelecek nesillere edinilen bilgi ve birikimlerin aktar─▒lmas─▒ ve geli┼čtirici olmas─▒ te┼čvik edilmi┼čtir. ├ç─▒kacak eserlerin nas─▒l ├ž├Âz├╝lece─či, staccato tekni─činin nas─▒l ├╝stesinden gelinebilece─či anlat─▒lm─▒┼čt─▒r. Staccato tekni─činin daha k─▒sa s├╝rede ├ž├Âz├╝me kavu┼čturulmas─▒ ama├ž edinilmi┼čtir. Parmaklar─▒n yerlerini ├Â─čretti─čimiz kadar belle─čimize de ├žal─▒┼čmalar─▒n kaydedilmesi ├Ânemlidir. G├Âsterilen azmin ve sabr─▒n sonucu olarak ortaya ├ž─▒kan yap─▒t ba┼čar─▒y─▒ daha da yukar─▒ seviyelere ├ž─▒karacakt─▒r

    Neuroanatomical and gene expression features of the rabbit accessory olfactory system. Implications of pheromone communication in reproductive behaviour and animal physiology

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    Mainly driven by the vomeronasal system (VNS), pheromone communication is involved in many species-specific fundamental innate socio-sexual behaviors such as mating and fighting, which are essential for animal reproduction and survival. Rabbits are a unique model for studying chemocommunication due to the discovery of the rabbit mammary pheromone, but paradoxically there has been a lack of knowledge regarding its VNS pathway. In this work, we aim at filling this gap by approaching the system from an integrative point of view, providing extensive anatomical and genomic data of the rabbit VNS, as well as pheromone-mediated reproductive and behavioural studies. Our results build strong foundation for further translational studies which aim at implementing the use of pheromones to improve animal production and welfare

    Genetic considerations in cerebral small vessel diseases

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    Cerebral small vessel disease (CSVD) encompasses a broad clinical spectrum united by pathology of the small vessels of the brain. CSVD is commonly identified using brain magnetic resonance imaging with well characterized markers including covert infarcts, white matter hyperintensities, enlarged perivascular spaces, and cerebral microbleeds. The pathophysiology of CSVD is complex involving genetic determinants, environmental factors, and their interactions. While the role of vascular risk factors in CSVD is well known and its management is pivotal in mitigating the clinical effects, recent research has identified novel genetic factors involved in CSVD. Delineating genetic determinants can promote the understanding of the disease and suggest effective treatments and preventive measures of CSVD at the individual level. Here we review CSVD focusing on recent advances in the genetics of CSVD. The knowledge gained has advanced understanding of the pathophysiology of CSVD, offered promising early results that may improve subtype identification of small vessel strokes, has led to additional identification of mendelian forms of small vessel strokes, and is getting closer to influencing clinical care through pharmacogenetic studies

    Macrophages from naked mole-rat possess distinct immunometabolic signatures upon polarization

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    The naked mole-rat (NMR) is a unique long-lived rodent which is highly resistant to age-associated disorders and cancer. The immune system of NMR possesses a distinct cellular composition with the prevalence of myeloid cells. Thus, the detailed phenotypical and functional assessment of NMR myeloid cell compartment may uncover novel mechanisms of immunoregulation and healthy aging. In this study gene expression signatures, reactive nitrogen species and cytokine production, as well as metabolic activity of classically (M1) and alternatively (M2) activated NMR bone marrow-derived macrophages (BMDM) were examined. Polarization of NMR macrophages under pro-inflammatory conditions led to expected M1 phenotype characterized by increased pro-inflammatory gene expression, cytokine production and aerobic glycolysis, but paralleled by reduced production of nitric oxide (NO). Under systemic LPS-induced inflammatory conditions NO production also was not detected in NMR blood monocytes. Altogether, our results indicate that NMR macrophages are capable of transcriptional and metabolic reprogramming under polarizing stimuli, however, NMR M1 possesses species-specific signatures as compared to murine M1, implicating distinct adaptations in NMR immune system

    OLIG2 neural progenitor cell development and fate in Down syndrome

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    Down syndrome (DS) is caused by triplication of human chromosome 21 (HSA21) and is the most common genetic form of intellectual disability. It is unknown precisely how triplication of HSA21 results in the intellectual disability, but it is thought that the global transcriptional dysregulation caused by trisomy 21 perturbs multiple aspects of neurodevelopment that cumulatively contribute to its etiology. While the characteristics associated with DS can arise from any of the genes triplicated on HSA21, in this work we focus on oligodendrocyte transcription factor 2 (OLIG2). The progeny of neural progenitor cells (NPCs) expressing OLIG2 are likely to be involved in many of the cellular changes underlying the intellectual disability in DS. To explore the fate of OLIG2+ neural progenitors, we took advantage of two distinct models of DS, the Ts65Dn mouse model and induced pluripotent stem cells (iPSCs) derived from individuals with DS. Our results from these two systems identified multiple perturbations in development in the cellular progeny of OLIG2+ NPCs. In Ts65Dn, we identified alterations in neurons and glia derived from the OLIG2 expressing progenitor domain in the ventral spinal cord. There were significant differences in the number of motor neurons and interneurons present in the trisomic lumbar spinal cord depending on age of the animal pointing both to a neurodevelopment and a neurodegeneration phenotype in the Ts65Dn mice. Of particular note, we identified changes in oligodendrocyte (OL) maturation in the trisomic mice that are dependent on spatial location and developmental origin. In the dorsal corticospinal tract, there were significantly fewer mature OLs in the trisomic mice, and in the lateral funiculus we observed the opposite phenotype with more mature OLs being present in the trisomic animals. We then transitioned our studies into iPSCs where we were able to pattern OLIG2+ NPCs to either a spinal cord-like or a brain-like identity and study the OL lineage that differentiated from each progenitor pool. Similar to the region-specific dysregulation found in the Ts65Dn spinal cord, we identified perturbations in trisomic OLs that were dependent on whether the NPCs had been patterned to a brain-like or spinal cord-like fate. In the spinal cord-like NPCs, there was no difference in the proportion of cells expressing either OLIG2 or NKX2.2, the two transcription factors whose co-expression is essential for OL differentiation. Conversely, in the brain-like NPCs, there was a significant increase in OLIG2+ cells in the trisomic culture and a decrease in NKX2.2 mRNA expression. We identified a sonic hedgehog (SHH) signaling based mechanism underlying these changes in OLIG2 and NKX2.2 expression in the brain-like NPCs and normalized the proportion of trisomic cells expressing the transcription factors to euploid levels by modulating the activity of the SHH pathway. Finally, we continued the differentiation of the brain-like and spinal cord-like NPCs to committed OL precursor cells (OPCs) and allowed them to mature. We identified an increase in OPC production in the spinal cord-like trisomic culture which was not present in the brain-like OPCs. Conversely, we identified a maturation deficit in the brain-like trisomic OLs that was not present in the spinal cord-like OPCs. These results underscore the importance of regional patterning in characterizing changes in cell differentiation and fate in DS. Together, the findings presented in this work contribute to the understanding of the cellular and molecular etiology of the intellectual disability in DS and in particular the contribution of cells differentiated from OLIG2+ progenitors

    The genetic inheritance and prevalence patterns of multiple sclerosis

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    Multiple sclerosis (MS) is an autoimmunological disease mainly categorized by nervous tissue breakdown caused by immune cells targeting the myelin sheath, along with ranging symptoms of disability. The disease has a complex genetic basis with many environmental factors also believed to play a role in pathology. The major histocompatibility complex (MHC) has the strongest understood genetic link to disease, but many other genes and mechanisms have been identified that likely also have an effect. Environmental factors discussed include viral agents, vitamin D, ultraviolet type B radiation, and birth month, among other factors. Cognition deficits are also sometimes seen in patients. Prevalence of MS varies significantly worldwide, with a so-called latitude effect, sex differences, and other factors increasing or decreasing disease rates. Many MS cases have a relapsing and remitting component, but there are also other somewhat distinct disease states, and often a progressive aspect to disease over time. Diagnosis is often done using the McDonald criteria, but cases can present in many ways and there are other diagnostic tools occasionally used in tandem. Treatment options have expanded in recent years, with injectable, oral, and monoclonal pharmaceutical drugs available as disease modifying therapies. Other treatments, potential future innovations, and treatment goals are mentioned. Physical therapy and exercise are recommended for most MS patients and can help to slow aspects of disability progression. Dietary changes and gut microbiota likely also play a role in disease state and could be adjusted to potentially help reduce symptoms. The Covid-19 pandemic and vaccination has complicated the treatment of MS patients
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