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The non-orthotopic expression of olfactory receptors (ORs) includes the male reproductive system, and in particular spermatozoa; their active ligands could be essential to sperm chemotaxis and chemical sperm–oocyte communication. OR51E2 expression has been previously reported on sperm cells' surface. It has been demonstrated in different cellular models that olfactory receptor 51E2 (OR51E2) binds volatile short-chain fatty acids (SCFAs) as specific ligands. In the present research, we make use of Western blot, confocal microscopy colocalization analysis, and the calcium-release assay to demonstrate the activation of sperm cells through OR51E2 upon SCFAs stimulus. Moreover, we perform a novel modified swim-up assay to study the involvement of OR51E2/SCFAs in sperm migration. Taking advantage of computer-assisted sperm analysis (CASA system), we determine the kinematics parameters of sperm cells migrating towards SCFAs-enriched medium, revealing that these ligands are able to promote a more linear sperm-cell orientation. Finally, we obtain SCFAs by mass spectrometry in cervico-vaginal mucus and show for the first time that a direct incubation between cervical mucus and sperm cells could promote their activation. This study can shed light on the possible function of chemosensory receptors in successful reproduction activity, laying the foundation for the development of new strategies for the treatment of infertile individuals. [ABSTRACT FROM AUTHOR]

Amyloid fibrils are polymeric structures originating from aggregation of misfolded proteins. In vivo, proteolysis may modulate amyloidogenesis and fibril stability. In light chain (AL) amyloidosis, fragmented light chains (LCs) are abundant components of amyloid deposits; however, site and timing of proteolysis are debated. Identification of the N and C termini of LC fragments is instrumental to understanding involved processes and enzymes. We investigated the N and C terminome of the LC proteoforms in fibrils extracted from the hearts of two AL cardiomyopathy patients, using a proteomic approach based on derivatization of N- and C-terminal residues, followed by mapping of fragmentation sites on the structures of native and fibrillar relevant LCs. We provide the first high-specificity map of proteolytic cleavages in natural AL amyloid. Proteolysis occurs both on the LC variable and constant domains, generating a complex fragmentation pattern. The structural analysis indicates extensive remodeling by multiple proteases, largely taking place on poorly folded regions of the fibril surfaces. This study adds novel important knowledge on amyloid LC processing: although our data do not exclude that proteolysis of native LC dimers may destabilize their structure and favor fibril formation, the data show that LC deposition largely precedes the proteolytic events documentable in mature AL fibrils. [ABSTRACT FROM AUTHOR]

The article reports on the public repository towards data of mass spectrometry (MS) imaging. It mentions the dependence of its graphical representation on the normalization of intensity, spatial interpolation and color scale. An overview of the Proteomics Standards Institute and its guidelines is also presented.

During the last decade, the evidences on the relationship between neurodevelopmental disorders and the microbial communities of the intestinal tract have considerably grown. Particularly, the role of gut microbiota (GM) ecology and predicted functions in Autism Spectrum Disorders (ASD) has been especially investigated by 16S rRNA targeted and shotgun metagenomics, trying to assess disease signature and their correlation with cognitive impairment or gastrointestinal (GI) manifestations of the disease. Herein we present a metaproteomic approach to point out the microbial gene expression profiles, their functional annotations, and the taxonomic distribution of gut microbial communities in ASD children. We pursued a LC-MS/MS based investigation, to compare the GM profiles of patients with those of their respective relatives and aged-matched controls, providing a quantitative evaluation of bacterial metaproteins by SWATH analysis. All data were managed by a multiple step bioinformatic pipeline, including network analysis. In particular, comparing ASD subjects with CTRLs, up-regulation was found for some metaproteins associated with Clostridia and with carbohydrate metabolism (glyceraldehyde-3-phosphate and glutamate dehydrogenases), while down-regulation was observed for others associated with Bacteroidia (SusC and SusD family together with the TonB dependent receptor). Moreover, network analysis highlighted specific microbial correlations among ASD subgroups characterized by different functioning levels and GI symptoms. To the best of our knowledge, this study represents the first metaproteomic investigation on the gut microbiota of ASD children compared with relatives and age-matched CTRLs. Remarkably, the applied SWATH methodology allowed the attribution of differentially regulated functions to specific microbial taxa, offering a novel and complementary point of view with respect to previous studies. [Display omitted] • SWATH analysis supported the metaproteomic outcome when comparing ASD and controls. • The gut microbiota of controls differs from both that of ASD and their relatives. • The enhanced functions in the gut microbiota of ASD are ascribed to Clostridia. [ABSTRACT FROM AUTHOR]

Gingival Crevicular Fluid (GCF), a plasma-derived exudate present in the gingival crevice was collected from deciduous, exfoliating and permanent teeth from 20 children (60 samples) with the aim to characterize and quantify by a mass spectrometry based top-down proteomic approach, the peptide/proteins in the fluid and verify possible variations occurring during the exfoliating process. The results obtained confirmed the presence in GCF of α-Defensins 1–4, Thymosin β4 and Thymosin β10, as described in previous works and revealed the presence of other interesting peptides never described before in GCF such as specific fragments of α-1-antitrypsin, α-1-antichymotrypsin; fragments of Thymosin β4 and Thymosin β10; Fibrinopeptide A and its fragments and Fibrinopeptide B; S100A8 and S100A9, LVV Hemorphin-7 (hemoglobin chain β fragment), as well as some other peptides deriving from α and β subunits of hemoglobin. Statistical analysis evidenced different levels in 5 proteins/peptides in the three groups. Our study demonstrate that an in-depth analysis of a biological fluid like GCF, present in small amount, can provide useful information for the understanding of different biological processes like teeth eruption. Data are available via ProteomeXchange with identifier PXD016010 and PXD016049. GCF due to his site-specific nature has a great potential in containing factors that are specific for action at a given site and might have diagnostic value to detect qualitative and quantitative variations of proteins/peptides composition linked to physiological or pathological conditions. • GCF was collected from deciduous, exfoliating and permanent teeth from 20 children. • Peptide/proteins content was characterized by a Top-Down MS proteomic approach. • The data help to understand complex biological processes like teeth eruption. • Data are available via ProteomeXcharge with identifier PXD016010 and PXD016049. Unlabelled Image [ABSTRACT FROM AUTHOR]

Food allergy is the disease where the immune system is elicited by antigens in food. Although innocuous for immune-tolerant individuals, an ever-growing number of food allergenic people are being registered worldwide. To date, no treatment to cure food allergy is available and the disease management relies on the careful exclusion of the allergenic food from the diet of the allergic individuals. Great efforts are ongoing to clarify the allergenic mechanisms of the diverse allergenic proteins of food origin, aimed to both designing suitable therapies and for a timely and precise diagnosis of the allergic condition. Among the other omics sciences, mass spectrometry (MS)-based proteomics is gaining a steadily increasing interest by the whole scientific community acknowledged its high versatility. In the present work, the latest proteomics based-studies on allergenic proteins are reviewed to provide guidance on the different MS-based methodologies adopted in the research on food allergens. Our review points to highlight the strengths of the MS-based proteomics and how these have been exploited to address specific research questions. Also, the most common drawbacks encountered in a proteomic study are discussed, providing an overview that helps novel researchers in choosing the more suitable experimental workflow. Wide wealth of knowledge arising from the various MS-based proteomic investigations is improving our understanding of food allergy through molecular characterization of food allergens. The present work reviews the key aspects to be evaluated while investigating food allergens by means of MS-based proteomics and provide guidance to the novel research groups approaching to the fascinating world of MS-based food allergens detection. Unlabelled Image • Food allergy represents a steadily increasing public health threat. • MS-based proteomics enables deep characterization of food allergens. • MS-proteomics unequivocally identifies multiple allergens per run. • Harmonization between allergen quantitation methods is needed. • Exploring sensibility is the next challenge of MS-based food allergen analysis. [ABSTRACT FROM AUTHOR]

Ependymoma pediatric brain tumor occurs at approximate frequencies of 10–15% in supratentorial and 20–30% in posterior fossa regions. These tumors have an almost selective response to surgery and relative and confirmed resistance to radiotherapy and chemotherapic agents, respectively. Alongside histopathological grading, clinical and treatment evaluation of ependymomas currently consider the tumor localization and the genomic outlined associated molecular subgroups, with the supratentorial and the posterior fossa ependymomas nowadays considered diverse diseases. On these grounds and in trying to better understand the molecular features of these tumors, the present investigation aimed to originally investigate the proteomic profile of pediatric ependymoma tissues of different grade and localization by mass spectrometry platforms to disclose potential distinct protein phenotypes. To this purpose, acid-soluble and acid-insoluble fractions of ependymoma tumor tissues homogenates were analyzed by LC-MS following both the top-down and the shotgun proteomic approaches, respectively, to either investigate the intact proteome or its digested form. The two approaches were complementary in profiling the ependymoma tumor tissues and showed distinguished profiles for supratentorial and posterior fossa ependymomas and for WHO II and III tumor grades. Top-down proteomic analysis revealed statistically significant higher levels of thymosin beta 4, 10 kDa heat shock protein, non-histone chromosomal protein HMG-17, and mono-/uncitrullinated forms ratio of the glial fibrillary acidic protein (GFAP) fragment 388–432 in supratentorial ependymomas—the same GFAP fragment as well as the hemoglobin alpha- and the beta-chain marked grade II with respect to grade III posterior fossa ependymomas. Gene ontology classification of shotgun data of the identified cancer and the non-cancer related proteins disclosed protein elements exclusively marking tumor localization and pathways that were selectively overrepresented. These results, although preliminary, seem consistent with different protein profiles of ependymomas of diverse grade of aggressiveness and brain region development and contributed to enlarging the molecular knowledge of this still enigmatic tumor. [ABSTRACT FROM AUTHOR]

In order to effectively develop personalized medicine for kidney diseases we urgently need to develop highly accurate biomarkers for use in the clinic, since current biomarkers of kidney damage (changes in serum creatinine and/or urine albumin excretion) apply to a later stage of disease, lack accuracy, and are not connected with molecular pathophysiology. Analysis of urine peptide content (urinary peptidomics) has emerged as one of the most attractive areas in disease biomarker discovery. Urinary peptidome analysis allows the detection of short and long-term physiological or pathological changes occurring within the kidney. Urinary peptidomics has been applied extensively for several years now in renal patients, and may greatly improve kidney disease management by supporting earlier and more accurate detection, prognostic assessment, and prediction of response to treatment. It also promises better understanding of kidney disease pathophysiology, and has been proposed as a "liquid biopsy" to discriminate various types of renal disorders. Furthermore, proteins being the major drug targets, peptidome analysis may allow one to evaluate the effects of therapies at the protein signaling pathway level. We here review the most recent findings on urinary peptidomics in the setting of the most common kidney diseases. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder in old age. Neurotoxicity of dopaminergic neurons triggered by aggregation of misfolded α-synuclein is a major pathogenic trait of PD. However, growing evidence indicates that peripheral processes, including metabolic changes, may precede and contribute to neurodegeneration. The present study was undertaken to identify a metabolic signature of PD through the quantification of serum amino acids and derivatives. Twenty older adults with PD (11 men and 9 women; mean age 73.1 ± 10.2 years) and 30 age-matched controls (14 men and 16 women; mean age 74.6 ± 4.3 years) were enrolled. A panel of 37 serum amino acids and derivatives was assessed by ultra-performance liquid chromatography/mass spectrometry. Partial least squares − discriminant analysis (PLS-DA) followed by double cross-validation was used to characterize the relationship between amino acid profiles and PD. The optimal complexity of the PLS-DA model was found to be three latent variables. The proportion of correct classifications was 99.3 ± 2.5% for participants with PD and 94.7 ± 3.0% for non-PD controls. Higher levels of β-amino butyric acid, cystine, ornithine, phosphoethanolamine, and proline defined the circulating amino acid profile of older people with PD. Controls were characterized by higher concentrations of 3-methyl-histidine, citrulline, and serine. Our findings indicate the existence of a distinct metabotype in older persons with PD. Future studies will have to establish whether changes in amino acid metabolism are involved in the pathogenesis of PD. This knowledge may be harnessed to identify novel disease biomarkers as well as new targets for interventions. • The complex pathophysiology of Parkinsons' disease (PD) hampers a comprehensive appraisal of the condition. • Metabolomics have emerged as a strategy for capturing the complexity of PD. • A specific pattern of circulating amino acids characterizes older adults with PD. • Metabotype analysis may assist early identification of PD in older people. [ABSTRACT FROM AUTHOR]

Breastfeeding is nowadays known to be one of the most critical factors contributing to the development of an efficient immune system. In the last decade, a consistent number of pieces of evidence demonstrated the relationship between a healthy organism and its gut microbiota. However, this link is still not fully understood and requires further investigation. We recently adopted a murine model to describe the impact of either maternal milk or parental genetic background, on the composition of the gut microbial population in the first weeks of life. A metaproteomic approach to such complex environments is a big challenge that requires a strong effort in both data production and analysis, including the set-up of dedicated multitasking bioinformatics pipelines. Herein we present an LC-MS/MS based investigation to monitor mouse gut microbiota in the early life, aiming at characterizing its functions and metabolic activities together with a taxonomic description in terms of operational taxonomic units. We provided a quantitative evaluation of bacterial metaproteins, taking into account differential expression results in relation to the functional and taxonomic classification, particularly with proteins from orthologues groups. This allowed the reduction of the bias arising from the presence of a high number of shared peptides, and proteins, among different bacterial species. We also focused on host mucosal proteome and its modulation, according to different microbiota composition. This paper would represent a reference work for investigations on gut microbiota in early life, from both a microbiological and a functional proteomic point of view. We focused on the shaping of the mouse gut microbiota in dependence on the feeding modality, defining a reliable taxonomic description, highlighting some functional characteristics of the microbial community, and performing a first quantitative evaluation by data independent analysis in metaproteomics. Unlabelled Image • Lack of IgA in breast milk favors Escherichia predominance. • Gut microbiota shaping is not driven by breastfeeding only. • The two cross-feeding conditions led to more similar gut microbial populations. • An altered microbiota composition could reflect in different host mucosal proteomes. [ABSTRACT FROM AUTHOR]