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Loss of ovarian function and estrogen therapy remodel the brain's synaptic and metabolic proteome.

Menopause is linked to cognitive decline and reduced brain metabolism, whereas estrogen (E2) therapy has been shown to mitigate these effects. Understanding the molecular mechanisms by which ovarian hormones and E2 influence neuroprotection is essential for developing strategies to maintain brain health in women. In this study, we examined how the loss of ovarian hormones, with or without E2 treatment, affects the brain proteome and mitochondrial energy production in aged female C57BL/6J mice (36-40 wk). The mice underwent sham or ovariectomy (OVX) surgery and were fed a high-fat diet for 10 wk; 6 wk after surgery, OVX mice received either sesame oil or E2 treatment for 4 wk. Proteomic analysis of brain homogenates revealed 4,992 proteins regulated by E2, with pathway analysis showing increased signaling proteins related to synaptogenesis. OVX reduced proteins involved in synaptic function, branched-chain amino acid and ketone metabolism, the tricarboxylic acid cycle, and oxidative phosphorylation (Complexes I, IV, and V), whereas E2 restored protein expression within these pathways. Despite alterations in OxPhos proteins, basal and state 3 mitochondrial respiration remained unchanged, although notable impairments in Complex IV enzymatic activity were apparent in OVX, which were partially reversed by E2 treatment. Overall, these results indicate that E2 supports brain health by maintaining proteins crucial for synaptic integrity and metabolism, while partially offsetting the functional decline in mitochondrial bioenergetics associated with menopause.NEW & NOTEWORTHY The menopausal transition, marked by declining estrogen levels, alters cognition, neuroplasticity, and brain metabolism. Although hormone therapy benefits cognition, its molecular effects on the brain remain unclear. Using whole-brain proteomics in aged ovariectomized (OVX) mice with or without estrogen treatment, we found that OVX reduced proteins linked to synaptogenesis and mitochondrial metabolism. Estrogen reversed these declines, restoring pathways supporting neuronal signaling and energy balance, identifying estrogen-regulated proteins critical for maintaining brain health during menopause.

Animals↗

What it takes to get a herbicide's mode of action. Physionomics, a classical approach in a new complexion.

Discovering new herbicides with novel modes of action is a priority assignment in plant protection research. However, for active compounds identified in greenhouse screens, the crucial point is to tread the most efficient path in determining a herbicide's target site, regarding chance of success, time and research costs. Today, in the literature, molecular (functional genomics, transcriptomics), biochemical (proteomics) and analytical (metabolomics) approaches are particularly discussed. So far, less attention has been focused on the comprehensive physiological profiling of the complex plant system as a procedure which enables new herbicides, with an unknown target site for their mode of action, to be screened rapidly. Here, the concept of an array of 'functional' bioassays is presented which has ultimately been developed from the classical tool of mode of action diagnosis by symptoms. These bioassays are designed to differentiate between the distinct responses of the multiple organization units (plant, tissue, meristematic cell, organelle), developmental stages, types of metabolism (phototrophic, heterotrophic) and physiological processes in the plant organism. The response pattern to a herbicide can be viewed as the end result of changes induced in the molecular and biochemical process chain and should be diagnostic of its physiological mode of action. The results can be interpreted directly or a fingerprint database for all known modes of action to be screened for analogy. The term 'physionomics' is proposed for this comprehensive physiological profiling of the plant system, following the parallel terminology of the molecular and biochemical 'omics' technologies. Physionomics procedures provide a first clue to the mode of action of a new herbicide that can direct more time-consuming and costly molecular, biochemical, histochemical or analytical studies to identify a target site more efficiently.

Biological Assay↗

A scaleable and integrated crystallization pipeline applied to mining the Thermotoga maritima proteome.

The wealth of genomic data available for many organisms has set the stage for the next phase of structure-function analysis. High-throughput structural genomics is currently the method of choice for rapid analysis of protein structure-function relationships on a proteome-wide basis. The Joint Center for Structural Genomics (JCSG), established in 2000 under the NIH/NIGMS Protein Structure Initiative, has developed and implemented an integrated high-throughput structure pipeline and applied it in a 2-tiered approach to mining the proteome of the thermophilic bacterium Thermotoga maritima. In the first tier, the successful application of this integrated pipeline has resulted in the cloning and expression of 73% of the T. maritima proteome (1376 out of 1877 predicted genes), and has identified 465 proteins which produced crystal hits. These 465 proteins were compared with existing structural information and a subset of 269 targets were selected to process towards structure determination in a second tier effort. To date, the JCSG pipeline applied to the Thermotoga maritima proteome has resulted in 55 new structures and has identified 6 novel folds and continues to identify structures with novel features.

Bacterial Proteins↗

From proteomics to genomics.

Presently, science is moving from genomics to proteomics in order to get insight into the functional network of gene expression. Actually however, proteomics is much older than genomics and dates back to the introduction of the two-dimensional gel electrophoresis technique (2-DE) independently by Klose and O'Farrell. Based on this approach almost all cellular proteins can be separated. New developments in mass spectrometry allowed identification of single spots in the 2-DE protein pattern, including the underlying genes. Joachim Klose has focused his pioneering 2-DE studies on mouse models with special emphasis on quantitative protein variants. According to him, proteins are living molecules exhibiting a characteristic protein phenotype.

Animals↗

[Research progress in SELDI-TOF MS and its clinical applications].

Proteinchip profiling is a powerful and innovative proteomic technology for biomarker discovery and diagnostic/prognostic assay development. Based on surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS), Ciphergen's proteinchip system offers a single, unified, high-throughput platform for a multitude of proteomic research applications. Proteins are the major functional components of the cell, the study of proteomics provides mankind with a better understanding of disease and life. The remarkable findings in disease biomarkers have shed light to the early diagnosis, monitoring and predicting prognosis of various diseases, especially for cancer. In this article, the development and technology of SELDI-TOF MS are introduced. Some research progress and encouraging research results in oncoproteomics, infectious diseases, neurological diseases and diabetes mellitus using SELDI-TOF MS are also reviewed. The paper is closed by the appraisals on its pros and cons, as well as the future prospective is also expounded.

Animals↗

Phosphoproteome profiling of transforming growth factor (TGF)-beta signaling: abrogation of TGFbeta1-dependent phosphorylation of transcription factor-II-I (TFII-I) enhances cooperation of TFII-I and Smad3 in transcription.

Transforming growth factor-beta (TGFbeta) signaling involves activation of a number of signaling pathways, several of which are controlled by phosphorylation events. Here, we describe a phosphoproteome profiling of MCF-7 human breast epithelial cells treated with TGFbeta1. We identified 32 proteins that change their phosphorylation upon treatment with TGFbeta1; 26 of these proteins are novel targets of TGFbeta1. We show that Smad2 and Smad3 have different effects on the dynamics of TGFbeta1-induced protein phosphorylation. The identified proteins belong to nine functional groups, e.g., proteins regulating RNA processing, cytoskeletal rearrangements, and proteasomal degradation. To evaluate the proteomics findings, we explored the functional importance of TGFbeta1-dependent phosphorylation of one of the targets, i.e., transcription factor-II-I (TFII-I). We confirmed that TGFbeta1 stimulated TFII-I phosphorylation at serine residues 371 and 743. Abrogation of the phosphorylation by replacement of Ser371 and Ser743 with alanine residues resulted in enhanced complex formation between TFII-I and Smad3, and enhanced cooperation between TFII-I and Smad3 in transcriptional regulation, as evaluated by a microarray-based measurement of expression of endogenous cyclin D2, cyclin D3, and E2F2 genes, and by a luciferase reporter assay. Thus, TGFbeta1-dependent phosphorylation of TFII-I may modulate TGFbeta signaling at the transcriptional level.

Amino Acid Substitution↗

Quantitative proteomic profiling of membrane proteins from the mouse brain cortex, hippocampus, and cerebellum using the HysTag reagent: mapping of neurotransmitter receptors and ion channels.

Analysis of the brain proteome and studying brain diseases through clinical biopsies and animal disease models require methods of quantitative proteomics that are sensitive and allow identification and quantification of low abundant membrane proteins from minute amount of tissue. Taking advantage of recently developed methods for isolation of membrane proteins from 10-20 mg brain tissue [Nielsen, P.Aa., Olsen, J.V., Podtelejnokov, A.V., Andersen, J.R., Mann, M., Wiśniewski, J.R., 2005. Proteomic mapping of brain plasma membrane proteins. Mol. Cell. Proteomics 4, 402--408] and the HysTag-quantification method [Olsen, J.V., Andersen, J.R., Nielsen, P.Aa., Nielsen, M.L., Figeys, D., Mann, M., Wiśniewski, J.R., 2004. HysTag---A novel proteomic qualification tool applied to differential analysis of membrane proteins from distinct areas of mouse brain. Mol. Cell. Proteomics 3, 82--92] we performed quantitative proteomic analysis of three functionally distinct compartments of mouse brain: cortex, hippocampus, and cerebellum. In total, 976 unique peptides corresponding to 555 unique proteins were quantified. Up to 20-fold differences in the levels of some proteins between brain areas were measured. For many quantified proteins--as for glutamate receptors, calcium channel subunits, and ATP-ases--an excellent correlation between our proteomic data and previously published mRNA expression levels or intensity of immunostaining was found. Our results clearly demonstrate differences in levels of membrane proteins mapped in distinct brain compartments and offer a technology that allows in depth study of brain membrane proteomes, such as mouse models of neurological diseases.

Animals↗

Protein microarrays: molecular profiling technologies for clinical specimens.

Proteomics, the study of protein function within biologic systems, will further our understanding of cancer pathogenesis. Coupled with transcript profiling, proteomics can herald the advent of molecular therapy tailored to the individual patient's neoplasm. Protein microarrays, one emerging class of proteomic technologies, have broad applications for discovery and quantitative analysis. This technology is uniquely suited to gather information about the post-translational modifications of proteins reflecting the activity state of signal pathways and networks. Protein microarrays now make it feasible to conduct signal network profiling within cellular samples. Nevertheless, to be successful, design and use of protein microarrays must take into consideration enormous analytical challenges. A subclass of protein microarrays, Reverse Phase Arrays, created to meet these challenges, has been optimized for use with tissue specimens, and is now in use for the analysis of biopsy samples for clinical trial research.

Antibodies↗

Proteomic analysis of Bacillus anthracis Sterne vegetative cells.

Mass spectrometry and proteomics have found increasing use as tools for the rapid detection of pathogenic bacteria, even when they are in a mixture of non-pathogenic relatives. The success of this technique is greatly augmented by the availability of publicly accessible proteomic databases for specific pathogenic bacteria. To aid proteomic detection analyses for the causative agent of anthrax, we have constructed a comprehensive proteomic catalogue of vegetative Bacillus anthracis Sterne cells using liquid chromatography tandem-mass spectrometry. Proteins were separated by molecular weight or isoelectric point prior to tryptic digestion. Alternatively, the whole protein extract was digested and tryptic peptides were separated by cation exchange chromatography prior to Reverse Phase-LC-MS/MS. The use of three complementary, pre-analytical separation techniques resulted in the identification of 1048 unique proteins, including 694 cytosolic, 153 membrane (including 27 cell wall), and 30 secreted proteins, accounting for 19% of the total predicted proteome. Each identified protein was functionally categorized using the gene attribute database from TIGR CMR. These results provide a large proteomic catalogue of vegetative B. anthracis cells and, coupled with the recent proteomic catalogue of B. anthracis spore proteins, form a thorough summary of proteins expressed in the active and dormant stages of this organism.

Bacillus anthracis↗

Predicting post-synaptic activity in proteins with data mining.

The bioinformatics problem being addressed in this paper is to predict whether or not a protein has post-synaptic activity. This problem is of great intrinsic interest because proteins with post-synaptic activities are connected with functioning of the nervous system. Indeed, many proteins having post-synaptic activity have been functionally characterized by biochemical, immunological and proteomic exercises. They represent a wide variety of proteins with functions in extracellular signal reception and propagation through intracellular apparatuses, cell adhesion molecules and scaffolding proteins that link them in a web. The challenge is to automatically discover features of the primary sequences of proteins that typically occur in proteins with post-synaptic activity but rarely (or never) occur in proteins without post-synaptic activity, and vice-versa. In this context, we used data mining to automatically discover classification rules that predict whether or not a protein has post-synaptic activity. The discovered rules were analysed with respect to their predictive accuracy (generalization ability) and with respect to their interestingness to biologists (in the sense of representing novel, unexpected knowledge).

Database Management Systems↗

Cutting-edge technology. II. Proteomics: core technologies and applications in physiology.

Technologies for proteomics, e.g., studies examining the protein complement of the genome, have been in development for over 20 years. More recently, proteomics has become formalized by combining techniques for large-scale protein separation with very precise, high-fidelity approaches that analyze, identify, and characterize the separated proteins. These methods bring to reality the powerful scope of proteomics, enabling researchers to investigate cellular function at the protein level and thus representing one of proteomics' most fitting applications. In this review, we take a brief and concise look at some of the current, physiologically relevant technologies that comprise proteomics and report specific applications in which proteomics has provided valuable biological insight.

Animals↗

Global approaches to protein-protein interactions.

The availability of complete, annotated genome sequences for a variety of eukaryotic organisms has paved the way for a paradigm shift in biomedical research from the 'one gene-one hypothesis' approach to more global, systematic strategies that analyse genes or proteins on a genome- and proteome-wide scale. One daunting task in the post-genome era is to determine how the complement of expressed cellular proteins - the proteome - is organised into functional, higher-order networks, by mapping all constitutive and dynamic protein-protein interactions. Traditionally, reductionist approaches have typically focused on a few, selected gene products and their interactions in a particular physiological context. In contrast, more holistic strategies aim at understanding complex biological systems, for example global protein-protein interaction networks on a cellular or organismal level. Several large-scale proteomics technologies have been developed to generate comprehensive, cellular protein-protein interaction maps.

Eukaryotic Cells↗

Stabilization of ubiquitous mitochondrial creatine kinase preprotein by APP family proteins.

Amyloid precursor protein (APP) is involved in the pathogenesis of Alzheimer's disease (AD). However, the physiological role of APP and its family members is still unclear. To gain insights into APP function, we used a proteomic approach to identify APP interacting proteins. We report here for the first time a direct interaction between the C-terminal region of APP family proteins and ubiquitous mitochondrial creatine kinase (uMtCK). This interaction was confirmed in vitro as well as in cultured cells and in brain. Interestingly, expression of full-length and C-terminal domain of APP family proteins stabilized uMtCK preprotein in cultured cells. Our data suggest that APP may regulate cellular energy levels and mitochondrial function via a direct interaction and stabilization of uMtCK.

Amino Acid Sequence↗

Proteomic identification of the involvement of the mitochondrial rieske protein in epilepsy.

PURPOSE: Kindled seizures are widely used to model epileptogenesis, but the molecular mechanisms underlying the attainment of kindling status are largely unknown. Recently we showed that achievement of kindling status in the Sprague-Dawley rat is associated with a critical developmental interval of 25 +/- 1 days; the identification of this long, well-defined developmental interval for inducing kindling status makes possible a dissection of the cellular and genetic events underlying this phenomenon and its relation to normal and pathologic brain function. METHODS: By using proteomics on cerebral tissue from our new rat kindling model, we undertook a global analysis of protein expression in kindled animals. Some of the identified proteins were further investigated by using immunohistochemistry. RESULTS: We report the identification of a modified variant of the Rieske iron-sulfur protein, a component of the mitochondrial cytochrome bc1 complex, whose isoelectric point is shifted toward more alkaline values in the hippocampus of kindled rats. By immunohistochemistry, the Rieske protein is well expressed in the hippocampus, except in the CA1 subfield, an area of selective vulnerability to seizures in humans and animal models. We also noted an asymmetric, selective expression of the Rieske protein in the subgranular neurons of the dorsal dentate gyrus, a region implicated in neurogenesis. CONCLUSIONS: These results indicate that the Rieske protein may play a role in the response of neurons to seizure activity and could give important new insights into the molecular pathogenesis of epilepsy.

Animals↗

Proteomic profiling of metalloprotease activities with cocktails of active-site probes.

Metalloproteases are a large, diverse class of enzymes involved in many physiological and disease processes. Metalloproteases are regulated by post-translational mechanisms that diminish the effectiveness of conventional genomic and proteomic methods for their functional characterization. Chemical probes directed at active sites offer a potential way to measure metalloprotease activities in biological systems; however, large variations in structure limit the scope of any single small-molecule probe aimed at profiling this enzyme class. Here, we address this problem by creating a library of metalloprotease-directed probes that show complementary target selectivity. These probes were applied as a 'cocktail' to proteomes and their labeling profiles were analyzed collectively using an advanced liquid chromatography-mass spectrometry platform. More than 20 metalloproteases were identified, including members from nearly all of the major branches of this enzyme class. These findings suggest that chemical proteomic methods can serve as a universal strategy to profile the activity of the metalloprotease superfamily in complex biological systems.

Affinity Labels↗

Rendezvin: An essential gene encoding independent, differentially secreted egg proteins that organize the fertilization envelope proteome after self-association.

Preventing polyspermy during animal fertilization relies on modifications to the egg's extracellular matrix. On fertilization in sea urchins, the contents of cortical granules are secreted and rapidly assemble into the egg's extracellular vitelline layer, forming the fertilization envelope, a proteinaceous structure that protects the zygote from subsequent sperm. Here, we document rendezvin, a gene whose transcript is differentially spliced to yield proteins destined for either cortical granules or the vitelline layer. These distinctly trafficked variants reunite after cortical granule secretion at fertilization. Together, they help coordinate assembly of the functional fertilization envelope, whose proteome is now defined in full.

Alternative Splicing↗

The relationship between protein sequences and their gene ontology functions.

BACKGROUND: One main research challenge in the post-genomic era is to understand the relationship between protein sequences and their biological functions. In recent years, several automated annotation systems have been developed for the functional assignment of uncharacterized proteins. The underlying assumption of these systems is that similar sequences imply similar biological functions. However, it has been noted that matching sequences do not always infer similar functions. RESULTS: In this paper, we present the correlation between protein sequences and protein functions for the yeast proteome in the context of gene ontology. A novel measure is introduced to define the overall similarity between two protein sequences. The effects of the level as well as the size of a gene ontology group on the degree of similarity were studied. The similarity distributions at different levels of gene ontology trees are presented. To evaluate the theoretical prediction power of similar sequences, we computed the posterior probability of correct predictions. CONCLUSION: The results indicate that protein pairs of similar biological functions tend to have higher sequence similarity, although the similarity distribution in each functional group is heterogeneous and varies from group to group. We conclude that sequence similarity can serve as a key measure in protein function prediction. However, the resulting annotations must be verified through other means. A method that combines a broader range of measures is more likely to provide more accurate prediction. Our study indicates that the posterior probability of a correct prediction could serve as one of the key measures.

Amino Acid Sequence↗

Proteomics in postgenomic neuroscience: the end of the beginning.

Proteomics is complementary to genomic approaches anchored in DNA and RNA. Global characterization of proteins is providing new insights into general biological structures as well as synapses, receptor complexes and other neuronal and glial features. Current challenges for proteomics of the nervous system include problems relating to sample preparation, brain complexity, limited databases and informatics tools. The combination of proteomics with other global functional genomic approaches at the levels of genome and transcriptome, together with network biology, will provide important bridges between genes, physiology and pathology.

Animals↗