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Molecular aspects of sex differentiation.

Mammalian sex differentiation involves the action of a cascade of genes. Discovery of the sex-determining region of the Y chromosome (SRY) marked the beginning of the delineation of the genes in the cascade. Studies of the genetics of mammalian sex reversal and the embryogenesis of the mice are essential in this endeavor. A number of genes involved in the pathway have been identified and all except one of these genes have a putative role in male sex differentiation. Besides SRY being the master switch in male sex differentiation the hierarchical relationship of the genes identified are far from being understood. Similarly, our knowledge of the genetic regulation of female sex differentiation is minimal. Differential screening and gene expression profiling bring a new dimension to the pursuit with the identification of a number of genes previously unknown to be involved in sex differentiation. Wider application of functional genomic techniques and introduction of proteomic analyses are expected to shed light to our understanding of this complicated developmental process.

Animals↗

Mitochondrial biogenesis and remodeling during adipogenesis and in response to the insulin sensitizer rosiglitazone.

White adipose tissue is an important endocrine organ involved in the control of whole-body metabolism, insulin sensitivity, and food intake. To better understand these functions, 3T3-L1 cell differentiation was studied by using combined proteomic and genomic strategies. The proteomics approach developed here exploits velocity gradient centrifugation as an alternative to isoelectric focusing for protein separation in the first dimension. A 20- to 30-fold increase in the concentration of numerous mitochondrial proteins was observed during adipogenesis, as determined by mass spectrometry and database correlation analysis. Light and electron microscopy confirmed a large increase in the number of mitochondrion profiles with differentiation. Furthermore, mRNA profiles obtained by using Affymetrix GeneChips revealed statistically significant increases in the expression of many nucleus-encoded mitochondrial genes during adipogenesis. Qualitative changes in mitochondrial composition also occur during adipose differentiation, as exemplified by increases in expression of proteins involved in fatty acid metabolism and of mitochondrial chaperones. Furthermore, the insulin sensitizer rosiglitazone caused striking changes in mitochondrial shape and expression of selective mitochondrial proteins. Thus, although mitochondrial biogenesis has classically been associated with brown adipocyte differentiation and thermogenesis, our results reveal that mitochondrial biogenesis and remodeling are inherent to adipose differentiation per se and are influenced by the actions of insulin sensitizers.

3T3 Cells↗

MSAP, the meichroacidin homolog of carp (Cyprinus carpio), differs from the rodent counterpart in germline expression and involves flagellar differentiation.

To gain access to the molecular mechanisms of spermatogenesis, the genes from a subtractive screen of the carp testis cDNA library were investigated. In this study, a male-specific homolog of the meichroacidin gene, called MSAP (MORN motif-containing sperm-specific axonemal protein), was isolated and further characterized. Database search and zoo-Western blot analyses revealed that MSAP homologs might be widespread in a variety of phyla but divergent in their C-terminal length and sequences. Carp MSAP is exclusively transcribed in testis, while mouse meichroacidin message is present in gonads of both sexes, although especially enriched in testis. In mouse, meichroacidin is expressed in male germ cells of meiotic stages, while carp MSAP is expressed during late spermiogenesis and accumulated in mature spermatozoa, in which MSAP is localized to the basal body and flagellum. Contrary to mouse meichroacidin revealed previously, existence of multiple pI variants of MSAP in two-dimensional electrophoresis suggested regulatory differences of the homologous molecules between mammal and teleost. These results indicate that MSAP homologs may play different roles in male germline development between vertebrates. Proteomic analysis and immunolocalization disclosed that MSAP is associated with septin7, a conserved GTPase that may participate in cellular morphogenesis, in the basal body of carp sperm. These findings suggest the involvement of carp MSAP in flagellar differentiation during spermiogenesis.

Animals↗

A survey of the plant mitochondrial proteome in relation to development.

To expand the functional analysis of plant mitochondria, we have undertaken the building of the proteome of pea mitochondria purified from leaves (green and etiolated), roots and seeds. In the first stage, we focused our proteomic exploration on the soluble protein complement of the green leaf mitochondria. We used traditional two-dimensional polyacrylamide gel electrophoresis, in combination with size exclusion chromatography as a third dimension, to identify the major proteins and further resolve their macromolecular complexity. The two-dimensional map of soluble proteins of green leaf mitochondria revealed 433 spots (with Coomassie blue staining) and around 73% of the proteins (in mass) were identified using three different approaches: Edman degradation, matrix-assisted laser desorption/ionization mass spectrometry and electrospray ionization tandem mass spectrometry. Quite a lot of the polypeptides were present in multiforms which indicated the presence of isoforms or the occurrence of post-translational modifications. Among these proteins, we uncovered an abundant family that was identified as aldehyde dehydrogenases, representing approximately 7.5% of the soluble proteins. The comparative analysis of soluble mitochondrial proteomes led to the identification of a number of proteins which were specifically present in root or in seed mitochondria, thus revealing the impact of tissue differentiation at the mitochondrial level.

Cell Fractionation↗

Guanidination chemistry for qualitative and quantitative proteomics.

The application of guanidination chemistry, the conversion of lysine into homoarginine residues, is used to illustrate several important general considerations relating to the use of differential isotope labelling for relative quantification in proteomics. The derivatisation procedure has been optimised for automation using a liquid handling station designed for proteomics. Automated application of the procedure to the analysis of in-gel tryptic digests of multiple spots from the two-dimensional gel electrophoretic (2DE) analysis of proteins from the FDCP-mix cell line shows near-universal improvement in protein identification as a result of derivatisation. This chemistry has been extended for relative quantification, applicable to matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS) and also tandem mass spectrometry (MS/MS). It provides a robust method for the quantitative comparison of two samples that have been separated by 2DE. A peptide pair may display poor detection during MS analysis, causing their reliable relative quantification to be difficult. In such circumstances, the additional selectivity of detection provided by MS/MS can substantiate identification and allow relative quantification of these species via product ion signal ratios.

Animals↗

Diagnosis of Ovarian Cancer Using Decision Tree Classification of Mass Spectral Data.

Recent reports from our laboratory and others support the SELDI ProteinChip technology as a potential clinical diagnostic tool when combined with $n$ -dimensional analyses algorithms. The objective of this study was to determine if the commercially available classification algorithm biomarker patterns software (BPS), which is based on a classification and regression tree (CART), would be effective in discriminating ovarian cancer from benign diseases and healthy controls. Serum protein mass spectrum profiles from 139 patients with either ovarian cancer, benign pelvic diseases, or healthy women were analyzed using the BPS software. A decision tree, using five protein peaks resulted in an accuracy of 81.5% in the cross-validation analysis and 80%in a blinded set of samples in differentiating the ovarian cancer from the control groups. The potential, advantages, and drawbacks of the BPS system as a bioinformatic tool for the analysis of the SELDI high-dimensional proteomic data are discussed.

Journal Article↗

Solubilization, two-dimensional separation and detection of the cardiac myofilament protein troponin T.

Proteomics strongly relies on the separation of complex protein mixtures, with two-dimensional electrophoresis (2-DE) being a commonly used technique. However efficient separation requires adequate solubilization of the original sample which will determine whether all proteins are accurately represented. Cardiac muscle has presented a particular challenge to solubilization. Here we have optimized the solubilization, separation and detection of the myofilament protein troponin T (TnT). Human left ventricular tissue from a rejected donor transplant heart was homogenized under 19 different conditions and subjected to 2-DE and Western blot analysis for TnT. The optimal conditions for isoelectric focusing of intact TnT requires homogenization in 6 M urea, 2.5 M thiourea, 4% 3-[(3-cholamidopropyl)dimethylamino]-1-propanesulfonate, with the addition of NaCl (2.5 M final concentration). TnT degradation products present in this severely damaged heart however, were differentially extracted from both each other and the intact molecule under the various conditions used. Despite adequate focusing of TnT it was found that a nonglutaraldehyde silver staining protocol, that is compatible with subsequent mass spectrometry, has greatly reduced sensitivity for TnT compared to Coomassie blue. Thus, care is required to avoid misrepresentation of troponin T in proteomic analysis in cardiac tissue.

Blotting, Western↗

Proteomic analysis of a preneoplastic phenotype in ovarian surface epithelial cells derived from prophylactic oophorectomies.

OBJECTIVE: To study the pattern of protein expression associated with a predisposition to develop ovarian cancer. METHODS: Prophylactic oophorectomy is used to prevent ovarian carcinoma in high-risk populations who have a strong family history of breast/ovarian cancer. In ovarian specimens of these women, the ovarian surface epithelium (OSE), which is tissue of origin of epithelial ovarian cancer, often shows altered morphology, growth patterns and differentiation features that are believed to be preneoplastic. This study has used a proteomic approach, based on two-dimensional gel electrophoresis and mass spectrometry, to compare the protein profiles of OSE from women with a history of familial ovarian cancer (FH-OSE), i.e., at least two first-degree relatives with such cancer and/or testing positive for BRCA1 mutations, to those without such history (NFH-OSE). RESULTS: Of >1500 protein spots, there were 8 proteins whose levels were significantly altered in FH-OSE. Three were known ovarian tumor associated proteins, others were novel changes. A number of the alterations seen were accompanied with protein modifications and have not been previously reported. There was a predominance of sequences related to the stress response pathway. Differential expression of selected genes was confirmed by Western blotting and real-time reverse transcription polymerase chain reaction. CONCLUSIONS: Our findings define the OSE phenotype of women at a high risk of developing ovarian cancer. Protein alterations seen in these tissues may represent an early, irreversible, non-mutational step in ovarian epithelial neoplastic progression and may be potential early and sensitive markers for the evaluation of cancer risk.

Adult↗

Proteome analysis of B-cell maturation.

Proteins affected by anti-mIgM stimulation during B-cell maturation were identified using 2-DE-based proteomics. We investigated the proteome profiles of stimulated and nonstimulated Ramos B-cells at eight time points during 5 d and compared the obtained proteomic data to the corresponding data from DNA-microarray studies. Anti-mIgM stimulation of the cells resulted in significant differences (> or =twofold) in the protein abundance close to 100 proteins and differences in post-translational protein modifications. Forty-eight up- or down-regulated proteins were identified by mass spectrometric methods and database searches. The identities of a further nine proteins were revealed by comparing their positions to the known proteins in other lymphocyte 2-DE databases. Several of the proteins are directly related to the functional and morphological characteristics of B-cells, such as cytoskeleton rearrangement and intracellular signalling triggered by the crosslinking of B-cell receptors. In addition to proteins known to be involved in human B-cell maturation, we identified several proteins that were not previously linked to lymphocyte differentiation. The results provide deeper insights into the process of B-cell maturation and may lead to novel therapeutic strategies for immunodeficiencies. An interactive 2-DE reference map is available at http://bioinf.uta.fi/BcellProteome.

B-Lymphocytes↗

Proteomic analysis of the entomopathogenic nematode Steinernema feltiae IS-6 IJs under evaporative and osmotic stresses.

In order to improve the storage capability under desiccation of the widely sold biological insecticides based on entomopathogenic nematodes (EPNs), we need to understand how these organisms respond to desiccation stress. As part of our studies to achieve this, we studied survival and protein expression in infective juveniles of the EPN Steinernema feltiae IS-6 when exposed to evaporative (exposure to 97% relative humidity (RH) for 3 days, followed by a 1-day exposure to 85% RH) and osmotic (exposure to 24% glycerol for 8h) stresses. More than 400 protein spots that were detected by proteomic analysis showed reproducible abundance within replications. Of these, 10 spots and 7 spots showed detectable changes in abundance under evaporative and osmotic stress, respectively, compared to fully hydrated nematodes. Three spots exhibited a differential response pattern between evaporative and osmotic desiccation (one was down regulated and two were novel in evaporative desiccation). Peptide mass mapping with MALDI-TOF mass spectrometry (MS) identified 10 desiccation-response proteins, among which several are known to be stress responsive including heat shock protein 60, coenzyme q biosynthesis protein, inositol monophosphatase and fumarate lyase that were found in both stresses. Other identified proteins are known to be involved in the cell cycle regulation, regulation of gene transcription, organization of macromolecular structure and some currently have no known functions. Our results suggest that it is unlikely that improvement of desiccation tolerance in EPNs can be achieved through genetic transformation and addition of single genes and that selective breeding could be the best approach to generate desiccation resistant worms.

Adaptation, Physiological↗

Uncovering the health implications of abandoned mines through protein profiling of local residents.

Residents in areas with abandoned mines risk significant exposure to abundant heavy metals in the environment. However, current clinical indicators cannot fully reflect the health changes associated with abandoned mine exposure. The aim of this study was to identify biological changes in the residents of abandoned mine areas via proteomic analysis of their blood. Blood samples were collected from abandoned mine and control areas, and mass spectrometry was used for protein profiling. A total of 138 unique or common proteins that were differentially expressed in low-exposure abandoned mine area (LoAMA) or high-exposure abandoned mine area (HiAMA) compared to non-exposure control area (NEA) were analyzed, and identified 4 clusters based on functional similarity. Among the 10 proteins that showed specific change in LoAMA, 4 proteins(Apolipoprotein M, Apolipoprotein E, Apolipoprotein L1, and Cholesteryl ester transfer protein) were cluded in cluster 1(plasma lipoprotein remodeling), and linked to proteins that showed specific change in protein expression in HiAMA. Therefore, it is suggested that 4 proteins are changed at low exposure to an abandoned mine (or initial exposure), and then at high exposure, changes in various proteins involved in linked plasma lipoprotein remodeling are induced, which might triggered by the 4 proteins. Interestingly, in addition to plasma lipoprotein remodeling, proteins involved in other functional networks were changed in the high exposure group. These were all directly or indirectly linked to the 4 biomarkers(Apolipoprotein M, Apolipoprotein E, Apolipoprotein L1, and Cholesteryl ester transfer protein) that changed during low exposure. This suggests their potential utility in identifying areas impacted by abandoned mines. Especially, proteins involved in lipid metabolism and renal function-related diseases in individuals exposed to heavy metals in abandoned mine areas were correlated. Chronic kidney disease is predominantly instigated by cardiovascular disease and is commonly accompanied by dyslipidemia.

Humans↗

Differential expression of glucose-regulated protein 78 during spermatogenesis.

The aim of the present study was to isolate and identify proteins involved in the process of spermatogenesis. To achieve this goal we used the technique of proteomic analysis. Comparison of testis protein patterns obtained by high-resolution two-dimensional gel electrophoresis from 1-week- and 7-week-old mice showed significant differences in protein spot intensities. Subsequently several of these variant protein spots were identified by mass spectrometry. Glucose-regulated protein (GRP) 78 (Bip) was one of them. GRP78, expressed at a lower level in 1-week-old mouse testes compared to 7-week-old mouse testes, is a member of the heat shock 70 protein family. It has recently been shown to be important for protecting cells from apoptosis in somatic cells, especially in progressively growing tumor cells. Further, immunohistochemical (IHC) analyses of mouse and human testes sections were performed to determine the cellular distribution of this protein. A strong GRP78 staining was seen beginning with pachytene spermatocytes. These findings suggested that GRP78 might perform an important function in the process of spermatogenesis.

Age Factors↗

Macrophage proteomic fingerprinting predicts HIV-1-associated cognitive impairment.

BACKGROUND: Specific proteins produced from monocytes may be linked to the pathogenesis and aid in the diagnosis of HIV-1-associated dementia (HAD). OBJECTIVE: The authors assessed whether a diagnostic phenomic protein profile could be obtained from monocyte-derived macrophages (MDM) from HIV-1-infected patients with cognitive impairment. METHODS: Twenty-one HIV-1-infected Hispanic women and 10 seronegative controls matched by age and sex were followed at the University of Puerto Rico Medical Sciences Campus, where neuropsychological, immune, and viral parameters were tested. Monocytes were recovered by Percoll gradient centrifugation from peripheral blood mononuclear cells. MDM lysates were prepared after 7 days of cultivation and protein profiles analyzed by surface enhanced laser desorption/ionization (SELDI)-time of flight (TOF) ProteinChip tests. Classification trees were prepared for statistical analyses. RESULTS: A total of 177 protein peaks from 2 to 80 kDa were evaluated in 31 patient MDM lysates by SELDI-TOF ProteinChip assays. Select protein peaks, at 5028 and 4320 Da, separated HIV-1-infected from HIV-1-seronegative subjects with a sensitivity of 100% and a specificity of 80%. Thirty-eight peaks were used to differentiate HIV-1-infected subjects with and without cognitive impairment. A 4348 Da protein separated the two groups with a sensitivity of 100% and a specificity of 75%. CONCLUSIONS: The identification of unique phenomic MDM profiles from cognitively impaired HIV-1-infected patients supports the hypothesis that changes in monocyte function parallel the development of HAD.

AIDS Dementia Complex↗

The microbial proteome database--an automated laboratory catalogue for monitoring protein expression in bacteria.

Laboratories devoted to high-throughput characterisation of purified proteins arrayed via two-dimensional (2-D) gel electrophoresis face an arduous task in maintaining a centralised and constantly evolving record of information relating to the characterisation of proteins and their responses following biological challenges. The Microbial Proteome Database (MPD) has been conceived as an in-house resource for complementing the plethora of genomic databases available for such organisms. The database utilises commercially available software to provide an electronic 'lab book' of information obtained daily from 2-D electrophoresis gels, image analysis packages, protein characterisation methodologies, and biological experimentation. The MPD begins from a single 2-D gel image (a 2-D 'reference map') with clickable spots that link to a 'protein catalogue' (ProtCat) with spot information including protein identity, changes in expression determined under experimental conditions, cellular location, mass, and pI. The entry for each protein then contains further links to gel images corresponding to the presence of the particular protein within different subproteomes (as defined by the pH of narrow- and wide-range immobilised pH gradients or from differential extraction methods used to determine the location of the protein within a functional cell). The database currently contains information from strains of three microbial species (Escherichia coil, Pseudomonas aeruginosa and Staphylococcus aureus) and 32 master gel images. The rapid accessibility of information obtained from microbial proteomes is an essential step towards the integrated analysis of these organisms at the gene, transcript, protein and functional levels and will aid in reducing turnaround times between sample preparation and the discovery of molecules of biological significance.

Automation↗

Proteomic analysis of Rickettsia prowazekii.

Rickettsia prowazekii is an obligate intracellular gram-negative bacterium. Comparative proteomics study of a virulent strain (Breinl) versus an avirulent strain (Madrid E) was performed using an integrated liquid chromatography and mass spectrometer. About 30% of predicted proteins were detected and identified. Among the detected proteins, more than 30 proteins were of unknown function in both strains. Although several proteins were detected in only one strain, the overall distribution of detected proteins in different COGs (clusters of orthologs groups) was very similar between the two strains. Functional analysis of differentially expressed proteins, either qualitatively or quantitatively, may lead to the discovery of pathogenesis-related factors.

Bacterial Proteins↗

Systematic Proteome Profiling of Maternal Plasma for Development of Preeclampsia Biomarkers.

Preeclampsia (PE) is a hypertensive disorder of pregnancy with various clinical symptoms. However, traditional markers for the disease including high blood pressure and proteinuria are poor indicators of the related adverse outcomes. Here, we performed systematic proteome profiling of plasma samples obtained from pregnant women with PE to identify clinically effective diagnostic biomarkers. Proteome profiling was performed using TMT-based liquid chromatography-mass spectrometry (LC-MS/MS) followed by subsequent verification by multiple reaction monitoring (MRM) analysis on normal and PE maternal plasma samples. Functional annotations of differentially expressed proteins (DEPs) in PE were predicted using bioinformatic tools. The diagnostic accuracies of the biomarkers for PE were estimated according to the area under the receiver-operating characteristics curve (AUC). A total of 1307 proteins were identified, and 870 proteins of them were quantified from plasma samples. Significant differences were evident in 138 DEPs, including 71 upregulated DEPs and 67 downregulated DEPs in the PE group, compared with those in the control group. Upregulated proteins were significantly associated with biological processes including platelet degranulation, proteolysis, lipoprotein metabolism, and cholesterol efflux. Biological processes including blood coagulation and acute-phase response were enriched for down-regulated proteins. Of these, 40 proteins were subsequently validated in an independent cohort of 26 PE patients and 29 healthy controls. APOM, LCN2, and QSOX1 showed high diagnostic accuracies for PE detection (AUC >0.9 and p&#xa0;<&#xa0;0.001, for all) as validated by MRM and ELISA. Our data demonstrate that three plasma biomarkers, identified by systematic proteomic profiling, present a possibility for the assessment of PE, independent of the clinical characteristics of pregnant women.

Humans↗

Quantitative proteomic analysis of the brain reveals the potential antidepressant mechanism of Jiawei Danzhi Xiaoyao San in a chronic unpredictable mild stress mouse model of depression.

OBJECTIVE: To reveal the antidepressant mechanisms of Jiawei DanZhiXiaoYaoSan (,JD) in chronic unpredictable mild stress (CUMS)-induced depression in mice. METHODS: Using the CUMS mouse model of depression, the antidepressant effects of JD were assessed using the sucrose preference test (SPT), forced swimming test (FST), and tail suspension test (TST). Tandem mass tag (TMT)-based quantitative proteomic analysis of the brain was performed following JD treatment. Hierarchical clustering, Gene Ontology function annotation, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and protein-protein interactions (PPIs) were used to analyze differentially expressed proteins (DEPs), which were further validated using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. RESULTS: Behavioral tests confirmed the anti-depressant effects of JD, and bioinformatics analysis revealed 59 DEPs, including 33 up-regulated and 26 down-regulated proteins, between the CUMS and JD-M groups. KEGG and PPI analyses revealed that neuro-filament proteins and the Ras signaling pathway may be key targets of JD in the treatment of depression. qRT-PCR and Western blotting results demonstrated that CUMS reduced the protein expression of neurofilament light (NEFL) and medium (NEFM) and inhibited the phosphorylation of extracellular regulated kinase 1/2 (ERK1/2), whereas JD promoted the phosphorylation of ERK1/2 and up-regulated the protein expression of NEFL and NEFM. CONCLUSIONS: The antidepressant mechanism of JD may be related to the up-regulation of p-ERK1/2 and neurofilament proteins.

Animals↗

Expression clustering reveals detailed co-expression patterns of functionally related proteins during B cell differentiation: a proteomic study using a combination of one-dimensional gel electrophoresis, LC-MS/MS, and stable isotope labeling by amino acids in cell culture (SILAC).

B cells play an essential role in the immune response. Upon activation they may differentiate into plasma cells that secrete specific antibodies against potentially pathogenic non-self antigens. To identify the cellular proteins that are important for efficient production of these antibodies we set out to study the B cell differentiation process at the proteome level. We performed an in-depth proteomic study to quantify dynamic relative protein expression patterns of several hundreds of proteins at five consecutive time points after lipopolysaccharide-induced activation of B lymphocytes. The proteome analysis was performed using a combination of stable isotope labeling using [13C6]leucine added to the murine B cell cultures, one-dimensional gel electrophoresis, and LC-MS/MS. In this study we identified 1,001 B cell proteins. We were able to quantify the expression levels of a quarter of all identified proteins (i.e. 234) at each of the five different time points. Nearly all proteins revealed changes in expression patterns. The quantitative dataset was further analyzed using an unbiased clustering method. Based on their expression profiles, we grouped the entire set of 234 quantified proteins into a limited number of 12 distinct clusters. Functionally related proteins showed a strong correlation in their temporal expression profiles. The quality of the quantitative data allowed us to even identify subclusters within functionally related classes of proteins such as in the endoplasmic reticulum proteins that are involved in antibody production.

Amino Acids↗