Implications for the practice of psychiatry.
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The design of database models and schemas for storing, cross-referencing, and retrieving neuroscience information faces issues that are similar but more complex than most of the other biomedical disciplines, such as genomics and proteonomics. Specifically, the visualization and manipulation of very large and diverse image data, such as digital brain atlases and functional magnetic resonance images, play a unique role in neuroscience while much of the associated information is textually recorded. Nongraphical information can include the annotation of large brain structures ranging from anatomical regions to intracellular structures, the description of cellular functional properties, and their various interrelationships, such as fiber connections. It is necessary that the heterogeneous and distributed types of data be cross-referenced to each other so that this diverse information can be efficiently retrieved, shared, and exchanged among the different neuroscientific disciplines. Continued advances in computers and Internet technologies appear to indicate that increasingly large data sets will be maintained on local or regional file servers and that informational interoperability will be achieved using a networked information system infrastructure. The authors and others have proposed and implemented models of semantically organized information systems that utilize centrally stored and highly structured archival information to index, cross-reference, and retrieve diverse, Web-based data sets.
BACKGROUND: Limited access to echocardiography can delay the diagnosis of suspected heart failure (HF), which in turn postpones the initiation of optimal guideline-directed medical therapy. Although natriuretic peptides like B-type natriuretic peptide (BNP) are valuable biomarkers for diagnosing and managing HF, the utility of combining BNP with other blood-based biomarkers to predict subtypes of new-onset HF remains underexplored. OBJECTIVES: This study sought to investigate and evaluate the diagnostic significance of adding blood-based biomarkers to BNP for identifying heart failure with preserved ejection fraction (HFpEF) or reduced ejection fraction (HFrEF), with the goal of enhancing diagnostic assays beyond BNP measurements. METHODS: We identified candidate blood protein biomarkers using untargeted proteomics workflows from a cohort of individuals recruited to the STOP-HF trial who were at risk of HF and subsequently developed either HFpEF or HFrEF over time ("HF progressors"; n = 40). Candidate biomarkers were verified in an independent cohort (n = 52) from a community-based rapid access HF diagnostic clinic. The biological processes associated with these proteins were assessed, and the diagnostic values of biomarker panels were evaluated using a machine learning approach. RESULTS: Within HF progressors, we identified 3 proteins associated with HFpEF development: vascular cell adhesion protein 1 (VCAM1), insulin-like growth factor 2 (IGF2), and inter-alpha-trypsin inhibitor heavy chain 3 (ITIH3). Additionally, 4 proteins were linked to HFrEF development: C-reactive protein (CRP), interleukin-6 receptor subunit beta (IL6RB), phosphatidylinositol-glycan-specific phospholipase D (PHLD), and noelin (NOE1). These findings were verified in an independent cohort to distinguish HF subtypes from controls. Moreover, a random forest algorithm demonstrated that combining these candidate biomarkers with BNP measurement significantly improved the prediction of HF subtypes. CONCLUSIONS: We identified candidate proteins linked to HFpEF and HFrEF in a longitudinal HF progressor cohort and validated them in a community-based cohort. Adding these proteins to BNP led to a significant improvement in HF subtype prediction. Study results have clinical implications for blood-based screening of HF subtypes using panels of biomarkers, particularly in resource-limited settings.
Fragile X Syndrome (FXS) is the most common inherited intellectual disability, and the most common monogenic cause of autism spectrum disorder (ASD). It is caused by epigenetic silencing of the FMR1 gene leading to the loss of FMRP, an RNA-binding protein that regulates local mRNA translation in neuronal dendrites, crucial for synapse development. Three-dimensional (3D) brain organoid models derived through in vitro differentiation of pluripotent stem cells offer a powerful tool to dissect the underlying mechanisms of neurodevelopmental disorders. Here, we generated human FXS and control organoids using isogenic human embryonic stem cell clones with and without the FXS mutation. Our results show that mature FXS cortical brain organoids can be derived by inhibiting the TGFβ and Wnt pathways. Moreover, expression analyses including immunofluorescence, qRT-PCR, proteomics and western blotting reveal altered levels of neuronal markers and ECM deposition along with modulated downstream signaling molecules. Interestingly, in silico analysis of proteomics revealed several altered pathways, such as cell adhesion, regulation of neurogenesis and cell cycle that are implicated in FXS. Collectively, our unique FXS-organoids derived from isogenic hESC lines may serve as a model for studying the pathology of FXS disorder and for developing therapeutical intervention.
In this review we discuss the merits and drawbacks with the use of proteomic and peptidomic strategies for identification of proteins and peptides in their multidimensional interactions in complex biological processes. The progress in proteomics and peptidomics during the last years offer us new challenges to study changes in the protein and peptide synthesis. These strategies also offer new tools to follow post-translational modifications and other disturbed chemical processes that may be indicative of pathophysiological alteration(s). Furthermore these techniques can contribute to improvements in the diagnosis and therapy of neurodegenerative diseases, such as Alzheimer's disease, and psychiatric diseases, as depression and post traumatic stress disorders. We also consider different practical aspects of the applications of mass spectrometry in clinical neuroscience, illustrated by example from our laboratories. The new proteomic and peptidomic strategies will further enable the progress for clinical neuroscience research.
Alzheimer's disease (AD) is characterized by Abeta peptide-containing plaques and tau-containing neurofibrillary tangles (NFTs). Both pathologies have been combined by crossing Abeta plaque-forming APP mutant mice with NFT-forming P301L tau mutant mice or by stereotaxically injecting beta-amyloid peptide 1-42 (Abeta42) into brains of P301L tau mutant mice. In cell culture, Abeta42 induces filamentous tau aggregates. To understand which processes are disrupted by Abeta42 in the presence of tau aggregates, we applied comparative proteomics to Abeta42-treated P301L tau-expressing neuroblastoma cells and the amygdala of P301L tau transgenic mice stereotaxically injected with Abeta42. Remarkably, a significant fraction of proteins altered in both systems belonged to the same functional categories, i.e. stress response and metabolism. We also identified model-specific effects of Abeta42 treatment such as differences in cell signaling proteins in the cellular model and of cytoskeletal and synapse associated proteins in the amygdala. By Western blotting (WB) and immunohistochemistry (IHC), we were able to show that 72% of the tested candidates were altered in human AD brain with a major emphasis on stress-related unfolded protein responsive candidates. These data highlight these processes as potentially important initiators in the Abeta42-mediated pathogenic cascade in AD and further support the role of unfolded proteins in the course of AD.
Experimental allergic encephalomyelitis (EAE) is an autoimmune disease characterized by demyelination and inflammatory infiltrates in the CNS, and it is an animal model of multiple sclerosis. Piperonyl butoxide (PBO) suppresses disease in EAE mice, and it exhibits a dual effect on cytochrome P450s that manifests in a transient inhibitory phase followed by induction. In order to identify the expression of proteins associated with EAE, a proteomic screening was performed on hindbrain microsomes from control + vehicle, control + PBO, EAE + vehicle, and EAE + PBO female mice. Glucose regulated protein 94 (Grp94) and coagulation factor VIII were among the proteins identified in EAE + vehicle and EAE + PBO mice. Immunohistochemical staining of Grp94 was present in some neurons and oligodendrocytes in hindbrain sections from control animals, and in some cells within inflammatory infiltrates in EAE animals. Since Grp94 (also known as Gp96) can partake in antigen presentation and induction of proinflammatory cytokine expression, its presence in these cells suggests that it may play a role in the pathogenesis of EAE. Coagulation factor VIII is carried and protected by von Willebrand factor. Immunohistochemical staining of von Willebrand factor revealed its presence in some vessels within hindbrain sections from control animals. In EAE animals, the number of labeled vessels was significantly increased, and extracellular granular deposits were observed around labeled vessels indicating that the breakdown of the blood-brain barrier that occurs in EAE permitted its extravasation into the CNS. Additional proteins were identified in the different groups of mice by proteomic screening, but confirmation of their expression profile awaits investigations by independent measures.
This study demonstrates the ability to perform sensitive proteome analysis on the limited protein quantities available through tissue microdissection. Capillary isoelectric focusing combined with nano-reversed-phase liquid chromatography in an automated and integrated platform not only provides systematic resolution of complex peptide mixtures based on their differences in isoelectric point and hydrophobicity but also eliminates peptide loss and analyte dilution. In comparison with strong cation exchange chromatography, the significant advantages of electrokinetic focusing-based separations include high resolving power, high concentration and narrow analyte bands, and effective usage of electrospray ionization-tandem MS toward peptide identifications. Through the use of capillary isoelectric focusing-based multidimensional peptide separations, a total of 6866 fully tryptic peptides were detected, leading to the identification of 1820 distinct proteins. Each distinct protein was identified by at least one distinct peptide sequence. These high mass accuracy and high-confidence identifications were generated from three proteome runs of a single glioblastoma multiforme tissue sample, each run consuming only 10 microg of total protein, an amount corresponding to 20,000 selectively isolated cells. Instead of performing multiple runs of multidimensional separations, the overall peak capacity can be greatly enhanced for mining deeper into tissue proteomics by increasing the number of CIEF fractions without an accompanying increase in sample consumption.
OBJECTIVE: Concern over neurologic injury limits safe duration of deep hypothermic circulatory arrest (DHCA) in surgery for congenital cardiac disease. Proteomics is a novel and powerful technique to study global protein changes in a given protein system. Using a neonatal model of cardiopulmonary bypass with DHCA, we sought to characterize the protein changes associated with DHCA brain injury. METHODS: Ten neonatal piglets were randomized to cardiopulmonary bypass with DHCA or sham operation. DHCA animals underwent induction of bypass (100 mL x kg(-1) x min(-1)), cooling to 18 degrees C, then DHCA for 60 minutes. Animals were rewarmed to normothermia, weaned from bypass, and harvested after 30 minutes off bypass. Sham animals underwent sternotomy without further instrumentation. Plasma samples were taken before bypass and before harvest. Proteins differentially expressed in the cerebral neocortex between the 2 groups were determined by 2-dimensional differential gel electrophoresis using fluorescent cyanine dyes and mass spectrometry. A second group of 4 piglets were similarly randomized and, after the experiment, tissues underwent perfusion-fixation for histologic examination. RESULTS: Cardiopulmonary bypass with DHCA caused extensive histologic and ultrastructural cerebral injury. Proteomic analysis of cerebral cortex found 10 protein spots to be differentially expressed; 9 were identified by mass spectrometry to represent 6 proteins, including apolipoprotein A-1, neurofilament-M protein, and enolase. Decreased expression of plasma apolipoprotein A-1 was found in DHCA. CONCLUSIONS: The acute protein changes associated with cerebral injury in a neonatal model of cardiopulmonary bypass with DHCA have been characterized. These may direct further research aimed at attenuating injury seen from cardiopulmonary bypass with DHCA.
Fish are distinctive in their enormous potential to continuously produce new neurons in the adult brain, whereas in mammals adult neurogenesis is restricted to the olfactory bulb and the hippocampus. In fish new neurons are not only generated in structures homologous to those two regions, but also in dozens of other brain areas. In some regions of the fish brain, such as the optic tectum, the new cells remain near the proliferation zones in the course of their further development. In others, as in most subdivisions of the cerebellum, they migrate, often guided by radial glial fibers, to specific target areas. Approximately 50% of the young cells undergo apoptotic cell death, whereas the others survive for the rest of the fish's life. A large number of the surviving cells differentiate into neurons. Two key factors enabling highly efficient brain repair in fish after injuries involve the elimination of damaged cells by apoptosis (instead of necrosis, the dominant type of cell death in mammals) and the replacement of cells lost to injury by newly generated ones. Proteome analysis has suggested well over 100 proteins, including two dozen identified ones, to be involved in the individual steps of this phenomenon of neuronal regeneration.
The purpose of this study is to determine the feasibility of the direct matrix-assisted laser desorption/ionization (MALDI) identification of proteins in fixed T47D breast cancer cells and murine brain tissues. The ability to identify proteins from cells and tissue may lead to biomarkers that effectively predict the onset of defined disease states, and their dynamic behavior could be an important hint for drug target discoveries. Direct tissue application of trypsin allows protein identification in cells and tissues, while maintaining spatial integrity and intracellular organization. Using a chemical printer, matrix was co-registered on trypsinized human T47D breast cancer cells and cryo-preserved sections of murine brain tissue, followed by MALDI post-source decay (PSD) or MALDI collision-induced dissociation (CID), respectively. Mass-to-charge (m/z) data from the cells and brain tissues were processed using Mascot software interrogation of the National Center for Biotechnology Information (NCBI) database. Histone H2B was identified from cultured T47D human breast cancer cells. Tubulin beta2 was identified from mouse brain cortex following an induced stroke. These results suggest that MALDI PSD/CID, combined with bioinformatics, can be used for the direct identification of proteins from cells and tissues. Refinements in preparation techniques may improve this approach to provide a tool for quantitative proteomics and clinical analysis.
Understanding the function of membrane proteins is of fundamental importance due to their crucial roles in many cellular processes and their direct association with human disorders. However, their analysis poses a special challenge, largely due to their highly amphipathic nature. Until recently, analyses of proteomic samples mainly were performed by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), due to the unprecedented separation power of the technique. However, in conventional 2D-PAGE membrane proteins are generally underrepresented due to their tendency to precipitate during isoelectric focusing and their inefficient transfer from the first to the second dimension. As a consequence, several other separation techniques, primarily based on liquid chromatography (LC), have been employed for analysis of this group of proteins. In the present study, different LC-based methods were compared for the analysis of crude protein extracts. One- and two-dimensional high-performance liquid chromatographic (1D- and 2D-HPLC) separations of brain protein tryptic digests with a predicted concentration range of up to 5 orders of magnitude were found to be insufficient, thus making a preceding fractionation step necessary. An additional protein separation step was introduced and a 3D-PAGE-HPLC analysis was performed. The results of these experiments are compared with results of 2D-PAGE/matrix-assisted laser desorption ionization mass spectrometric (MALDI MS) analyses of the same samples. Features, challenges, advantages, and disadvantages of the respective systems are discussed. The brain (mouse and human) was chosen as the analyzed tissue as it is of high interest in medical and pharmaceutical research into neurological diseases such as multiple sclerosis, stroke, Alzheimer's disease, and Parkinson's disease. The study is part of our ongoing research aimed at identifying new biomarkers for neurodegenerative diseases.
In contrast to mammals, adult teleost fish exhibit an enormous potential to regenerate neuronal tissue after injuries to the CNS. By combining a well-defined cerebellar lesion paradigm with differential proteome analysis at a post-lesion survival time of 3 days, we screened for protein candidates involved in repair of the fish brain. Out of nearly 900 protein spots detected on 2-D gels, spot intensity was significantly increased at least twofold in 30 spots and decreased to at least half the intensity of control tissue in 23 spots. The proteins associated with 24 of the spots were identified by PMF and MS/MS fragmentation. The cellular localization and the spatiotemporal patterns of two of these proteins, beta-actin and beta-tubulin, were further characterized through immunohistochemistry. Comparison of the observed changes in protein abundance with the previously characterized events underlying regeneration of the cerebellum suggests that the proteins identified are especially involved in cellular proliferation and survival, as well as axonal sprouting.
The senescence-accelerated prone mouse strain 8 (SAMP8) exhibits a remarkable age-accelerated deterioration in learning and memory. In this study, we identified carbonyl modification, a marker of protein oxidation, in liver and brain of SAMP8 from peptide mass fingerprints using MALDI-TOF mass spectrometry in combination with LC-MS/MS analysis. Carbonyl modification of Cu,Zn-superoxide dismutase (Cu,Zn-SOD) in liver at 3 month and hippocampal cholinergic neurostimulating peptide precursor protein (HCNP-pp) in brain at 9 month were higher in SAMP8 compared with control SAMR1. We demonstrated carbonyl modification of purified Cu,Zn-SOD increased by the reaction with H2O2. Therefore, progressive accumulation of oxidative damage to Cu,Zn-SOD, may cause dysfunction of defense systems against oxidative stress in SAMP8 with a higher oxidative states, leading to acceleration of aging. Furthermore, carbonyl modification of HCNP-pp may be involved in pathophysiological alterations associated with deterioration in the learning and memory in the brain seen in SAMP8.
BACKGROUND: The aetiology of Parkinson's disease (PD), an age-related disorder characterized by a progressive degeneration of dopaminergic neurons of the substantia nigra (SN) pars compacta, remains unclear. Current treatments, such as administration of L-DOPA, are only symptomatic and do not stop or delay the progressive loss of neurons. In fact, it has been suggested that the dopamine precursor L-DOPA, increases generation of reactive oxygen species (ROS) leading to further neuronal damage. A similar loss in nigrostriatal dopaminergic neurons is produced on intracerebral administration of the catecholaminergic neurotoxin 6-hydroxydopamine (6-OHDA). In an animal model of PD, termed 'the hemiparkinsonian rat', unilateral injection of 6-OHDA into the nigrostriatal pathway results in extensive loss of dopaminergic cells in the ipsolateral SN. In an attempt to identify some of the proteins that are involved in dopaminergic neuronal death, we used the proteomic methods to analyze this animal model of PD. METHODS: Five hemiparkinsonian rats were obtained by intranigral stereotaxic injection of 6-OHDA. The right 6-OHDA-lesioned substantia nigra and striatum tissues along with the left, unlesioned controlateral tissues, were excised and homogenized, using urea-based buffer, to extract the tissues protein. The separation of the protein mixtures and the visualization of the protein patterns obtained were performed using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Protein profiles of control and treated tissues were compare by the PDQuest 2D-gel analysis software (BIO-Rad laboratory). The protein spots showing differential expression were analysed by matrix assisted laser desorption/ionizing time of flight (MALDI-TOF) mass spectrometry. RESULTS: The brain protein extraction and solubilization protocol was validated obtaining a satisfactory protein profile. In comparison to the normal rats, hemiparkinsonian animals exhibited a different expression in alpha-enolase and beta-actin in substantia nigra and striatum, respectively. CONCLUSION: The proteomic study of 6-OHDA-induced lesions in the nigrostriatial pathway allowed us to identify two proteins, alpha-enolase and beta-actin, showing increased levels in the 6-OHDA-lesioned brain tissues compared to control. Previous studies described the same proteins as oxidized and proteins in Alzheimer's disease (AD) brain. Our preliminary data could mirror those results pointing out a common mechanism of neurodegenerative diseases.
To evaluate molecular events associated with the aging process in animal models and human tissues, microarray analysis is performed at the regional and cellular levels to define transcriptional patterns or mosaics that may lead to better understanding of the mechanism(s) that drive senescence. In this review, we outline the experimental and analytical issues associated with high-throughput genomic analyses in aging brain and other tissues for a comprehensive evaluation of the current state of microarray analysis in aging paradigms. Ultimately, the goal of these studies is to apply functional genomics and proteomics approaches to aging research to develop new tools to assess age in cell- and tissue-specific manners in order to develop aging biomarkers for pharmacotherapeutic interventions and disease prevention.
Peptide dimethylation with isotopically coded formaldehydes was evaluated as a potential alternative to techniques such as the iTRAQ method for comparative proteomics. The isotopic labeling strategy and custom-designed protein quantitation software were tested using protein standards and then applied to measure proteins levels associated with Alzheimer's disease (AD). The method provided high accuracy (10% error), precision (14% RSD) and coverage (70%) when applied to the analysis of a standard solution of BSA by LC-MS/MS. The technique was then applied to measure protein abundance levels in brain tissue afflicted with AD relative to normal brain tissue. 2-D LC-MS analysis identified 548 unique proteins (p<0.05). Of these, 349 were quantified with two or more peptides that met the statistical criteria used in this study. Several classes of proteins exhibited significant changes in abundance. For example, elevated levels of antioxidant proteins and decreased levels of mitochondrial electron transport proteins were observed. The results demonstrate the utility of the labeling method for high-throughput quantitative analysis.