Publications by authors named "Irene Messana"

129 Publications

Oxidative and Proteolytic Inactivation of Alpha-1 Antitrypsin in Bronchopulmonary Dysplasia Pathogenesis: A Top-Down Proteomic Bronchoalveolar Lavage Fluid Analysis.

Front Pediatr 2021 23;9:597415. Epub 2021 Mar 23.

Dipartimento di Scienze della Vita e Sanità Pubblica, Unità Operativa Complessa di Neonatologia, Fondazione Policlinico Universitario A. Gemelli, Istituto di Ricovero e Cura a Carattere Scientifico, Rome, Italy.

The study investigates the role of the oxidative and proteolytic inactivation of alpha-1 antitrypsin (AAT) in the pathogenesis of bronchopulmonary dysplasia (BPD) in premature infants. Bronchoalveolar lavage fluid (BALF) samples were collected on the 3rd day of life from mechanically ventilated neonates with gestational age ≤ 30 weeks and analyzed without previous treatment (top-down proteomics) by reverse-phase high-performance liquid chromatography-electrospray ionization mass spectrometry. AAT fragments were identified by high-resolution LTQ Orbitrap XL experiments and the relative abundances determined by considering the extracted ion current (XIC) peak area. Forty preterm neonates were studied: 20 (50%) did not develop BPD (no-BPD group), 17 (42.5%) developed mild or moderate new-BPD (mild + moderate BPD group), and 3 (7.5%) developed severe new-BPD (severe BPD group). Eighteen fragments of AAT and a fragment of AAT oxidized at a methionine residue were identified: significantly higher values of AAT fragments 25-57, 375-418, 397-418, 144-171, and 397-418 with oxidized methionine were found in the severe BPD group. The significantly higher levels of several AAT fragments and of the fragment 397-418, oxidized in BALF of preterm infants developing BPD, underlie the central role of an imbalance between proteases and protease inhibitors in exacerbating lung injury and inducing most severe forms of BPD. The study has some limitations, and between them, the small sample size implies the need for further confirmation by larger studies.
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http://dx.doi.org/10.3389/fped.2021.597415DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8021761PMC
March 2021

HPLC-ESI-MS top-down analysis of salivary peptides of preterm newborns evidenced high activity of some exopeptidases and convertases during late fetal development.

Talanta 2021 Jan 25;222:121429. Epub 2020 Aug 25.

Laboratorio di Proteomica, Centro Europeo di Ricerca Sul Cervello, IRCCS Fondazione Santa Lucia, Roma, Italy. Electronic address:

To have information on the proteolytic activity of convertases and exo-peptidases on human salivary proteins, this study investigated the relative amounts of the truncated proteoforms in the saliva of preterm newborns and compared them with the relative amounts measured in saliva of at-term newborns, of babies (0-10 years old) and of adults. Results indicated that convertase(s), acting on acidic proline-rich proteins and histatin 3, and carboxypeptidase(s) acting on acidic proline-rich proteins, P-C peptide, histatin 6 and statherin were many folds more active in preterm newborns than in the other groups. Conversely, the aminopeptidase responsible for the removal of the N-terminal Asp residue of statherin was not active in preterm newborns, becoming active only several months after the normal term of delivery. The high activity of convertases determined in preterm newborns suggests that it is required for the molecular events connected to the fetus development, and encourages further studies devoted to the characterization of their specific substrates.
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http://dx.doi.org/10.1016/j.talanta.2020.121429DOI Listing
January 2021

Top down proteomic analysis of gingival crevicular fluid in deciduous, exfoliating and permanent teeth in children.

J Proteomics 2020 08 3;226:103890. Epub 2020 Jul 3.

Laboratorio di Proteomica e Metabonomica-IRCCS Fondazione Santa Lucia, Roma, Italy.

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. SIGNIFICANCE: 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.
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http://dx.doi.org/10.1016/j.jprot.2020.103890DOI Listing
August 2020

Top-Down Proteomics of Human Saliva Discloses Significant Variations of the Protein Profile in Patients with Mastocytosis.

J Proteome Res 2020 08 6;19(8):3238-3253. Epub 2020 Jul 6.

Dipartimento di Scienze della Vita e dell'Ambiente, Università di Cagliari, 09124 Cagliari, Italy.

Mastocytosis is a myeloproliferative neoplasm causing abnormal clonal mast cell accumulation in different tissues, such as skin and bone marrow. A cutaneous subtype (CM) is distinguished from a systemic one (SM); SM patients can be grouped into SM with (SM+C) or without (SM-C) additional cutaneous lesions, and their classification is often challenging. This study was purposed to highlight variations in the salivary proteome of patients with different mastocytosis subtypes and compared to healthy controls. A top-down proteomics approach coupled to a label-free quantitation revealed salivary profiles in patients different from those of controls and a down-regulation of peptides/proteins involved in the mouth homeostasis and defense, such as statherin, histatins, and acidic proline-rich proteins (aPRPs), and in innate immunity and inflammation, such as the cathepsin inhibitors, suggesting a systemic condition associated with an exacerbated inflammatory state. The up-regulation of antileukoproteinase and S100A8 suggested a protective role against the disease status. The two SM forms were distinguished by the lower levels of truncated forms of aPRPs, statherin, P-B peptide, and cystatin D and the higher levels of thymosin β4 and α-defensins 1 and 4 in SM-C patients with respect to SM+C. Data are available via ProteomeXchange with identifier PXD017759.
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http://dx.doi.org/10.1021/acs.jproteome.0c00207DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8008451PMC
August 2020

Proteomic Analysis of the Acid-Insoluble Fraction of Whole Saliva from Patients Affected by Different Forms of Non-histaminergic Angioedema.

J Clin Immunol 2020 08 10;40(6):840-850. Epub 2020 Jun 10.

Dept of Life and Environmental Sciences, University of Cagliari, 09042, Monserrato, CA, Italy.

We analyzed by bidimensional electrophoresis the acid-insoluble fraction of saliva from three classes of angioedema patients and a healthy control group, highlighting significant variations of several normalized spot volumes. Characterization of the corresponding proteins was performed by in-gel tryptic digestion of the spots, followed by high-resolution HPLC-ESI-MS/MS analysis of tryptic mixtures. By this strategy, 16 differentially-expressed proteins among two or more groups were identified. We found higher concentration of proteins involved in immune response (interleukin-1 receptor antagonist and annexin A1), and of moonlighting proteins acting as plasminogen receptors (glyceraldehyde-3-phosphate dehydrogenase, α-enolase, and annexin A2) in patients affected by the idiopathic non-histaminergic or hereditary angioedema with unknown origin with respect to healthy controls. These data provide new information on the molecular basis of these less characterized types of angioedema. Graphical Abstract Graphical Abstract.
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http://dx.doi.org/10.1007/s10875-020-00802-wDOI Listing
August 2020

RP-HPLC-ESI-IT Mass Spectrometry Reveals Significant Variations of the Human Salivary Protein Profile Associated with Predominantly Antibody Deficiencies.

J Clin Immunol 2020 02 8;40(2):329-339. Epub 2020 Jan 8.

Department of Life and Environmental Sciences, University of Cagliari, Cittadella Univ. Monserrato, ss 554, 09042, Monserrato, CA, Italy.

Purpose: Present study is designed to discover potential salivary biomarkers associated with predominantly antibody deficiencies, which include a large spectrum of disorders sharing failure of antibody production, and B cell defects resulting in recurrent infections, autoimmune and inflammatory manifestations, and tumor susceptibility. Understanding and clinical classification of these syndromes is still challenging.

Methods: We carried out a study of human saliva based on liquid chromatography-mass spectrometry measurements of intact protein mass values. Salivary protein profiles of patients (n = 23) and healthy controls (n = 30) were compared.

Results: Patients exhibited lower abundance of α-defensins 1-4, cystatins S1 and S2, and higher abundance of glutathionylated cystatin B and cystatin SN than controls. Patients could be clustered in two groups on the basis of different levels of cystatin SN, S1 and S2, suggesting that these proteins may play different roles in the disease.

Conclusions: Quantitative variations of these pro-inflammatory and antimicrobial peptides/proteins may be related to immunodeficiency and infectious condition of the patients. The high incidence of tumors in the group with the highest level of cystatin SN, which is recognized as tumoral marker, appeared an intriguing result deserving of future investigations. Data are available via ProteomeXchange with identifier PXD012688.
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http://dx.doi.org/10.1007/s10875-020-00743-4DOI Listing
February 2020

Mapping of Transglutaminase-2 Sites of Human Salivary Small Basic Proline-Rich Proteins by HPLC-High-Resolution ESI-MS/MS.

J Proteome Res 2020 01 6;19(1):300-313. Epub 2019 Nov 6.

Department of Life and Environmental Sciences , University of Cagliari, Cittadella Univ. Monserrato , Monserrato, Cagliari 09042 , Italy.

Because of the distinctive features of the oral cavity, the determination of the proteins involved in the formation of the "oral protein pellicle" is demanding. The present study investigated the susceptibility of several human basic proline-rich peptides, named P-H, P-D, P-F, P-J, and II-2, as substrates of transglutaminase-2. The reactivity of the P-C peptide and statherin was also investigated. Peptides purified from human whole saliva were incubated with the enzyme in the presence or in the absence of monodansyl-cadaverine. Mass spectrometry analyses of the reaction products highlighted that P-H and P-D (P and A variants) were active substrates, II-2 was less reactive, and P-F and P-J showed very low reactivity. P-C and statherin were highly reactive. All of the peptides formed cyclo derivatives, and only specific glutamine residues were involved in the cycle formation and reacted with monodansyl-cadaverine: Q of P-H, Q of P-D, Q of II-2, Q of P-C, and Q of statherin were the principal reactive residues. One or two secondary glutamine residues of only P-H, P-D P, P-C, and statherin were hierarchically susceptible to the reaction with monodansyl-cadaverine. MS and MS/MS data were deposited to the ProteomeXchange Consortium ( http://www.ebi.ac.uk/pride ) via the PRIDE partner repository with the data set identifier PXD014658.
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http://dx.doi.org/10.1021/acs.jproteome.9b00527DOI Listing
January 2020

Enrichments of post-translational modifications in proteomic studies.

J Sep Sci 2020 Jan 6;43(1):313-336. Epub 2019 Nov 6.

Dipartimento di Scienze della Vita e dell'Ambiente, Università di Cagliari, Cagliari, Italy.

More than 300 different protein post-translational modifications are currently known, but only a few have been extensively investigated because modified proteoforms are commonly present in sub-stoichiometry amount. For this reason, improvement of specific enrichment techniques is particularly useful for the proteomic characterization of post-translationally modified proteins. Enrichment proteomic strategies could help the researcher in the challenging issue to decipher the complex molecular cross-talk existing between the different factors influencing the cellular pathways. In this review the state of art of the platforms applied for the enrichment of specific and most common post-translational modifications, such as glycosylation and glycation, phosphorylation, sulfation, redox modifications (i.e. sulfydration and nitrosylation), methylation, acetylation, and ubiquitinylation, are described. Enrichments strategies applied to characterize less studied post-translational modifications are also briefly discussed.
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http://dx.doi.org/10.1002/jssc.201900804DOI Listing
January 2020

Proteomics of the acid-soluble fraction of whole and major gland saliva in burning mouth syndrome patients.

Arch Oral Biol 2019 Feb 20;98:148-155. Epub 2018 Nov 20.

Institute of Chemistry of the Molecular Recognition - CNR, L.go F. Vito 1, 00168, Rome, Italy.

Objective: In the present study the salivary proteome of burning mouth syndrome patients and healthy subjects was characterized by a top-down proteomic approach and compared to highlight possible qualitative and quantitative differences that may give suggestions about the causes of this pathology which are still unknown.

Materials And Methods: Resting and stimulated whole saliva, stimulated parotid and submandibular/sublingual saliva samples were collected from burning mouth syndrome patients (n = 16) and age- and gender-matched healthy subjects (n = 14). An equal volume of 0.2% trifluoroacetic acid was added to each sample immediately after collection and the supernatants were analysed by liquid chromatography coupled to electrospray-ionisation mass spectrometry. Proteins and peptides were quantified using a label-free approach measuring the extracted ion current peak areas of the main salivary proteins and peptides.

Results: The quantitation of the main salivary proteins and peptides revealed a higher concentration of cystatin SN in resting saliva of burning mouth syndrome patients with respect to healthy controls and no other conspicuous changes.

Conclusions: The reported data showed that the salivary protein profile was not affected, in composition and relative abundance, by the burning mouth syndrome, except for the cystatin SN, a protein up-regulated in several pathological conditions, that might be considered potentially indicative of the disease.
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http://dx.doi.org/10.1016/j.archoralbio.2018.11.020DOI Listing
February 2019

Top-down proteomic profiling of human saliva in multiple sclerosis patients.

J Proteomics 2018 09 4;187:212-222. Epub 2018 Aug 4.

Department of Life and Environmental Sciences, Biomedical Section, University of Cagliari, Monserrato Campus, 09042 Monserrato, Cagliari, Italy.

Multiple sclerosis is a chronic disease of the central nervous system characterized by inflammation, demyelination and neurodegeneration which is of undetermined origin. To date a single diagnostic test of multiple sclerosis does not exists and novel biomarkers are demanded for a more accurate and early diagnosis. In this study, we performed the quantitative analysis of 119 salivary peptides/proteins from 49 multiple sclerosis patients and 54 healthy controls by a mass spectrometry-based top-down proteomic approach. Statistical analysis evidenced different levels on 23 proteins: 8 proteins showed lower levels in multiple sclerosis patients with respect to controls and they were mono- and di-oxidized cystatin SN, mono- and di-oxidized cystatin S1, mono-oxidized cystatin SA and mono-phosphorylated statherin. 15 proteins showed higher levels in multiple sclerosis patients with respect to controls and they were antileukoproteinase, two proteoforms of Prolactin-Inducible Protein, P-C peptide (Fr.1-14, Fr. 26-44, and Fr. 36-44), SV1 fragment of statherin, cystatin SN Des, cystatin SN P → L variant, and cystatin A T → M variant. The differences observed between the salivary proteomic profile of patients suffering from multiple sclerosis and healthy subjects is consistent with the inflammatory condition and altered immune response typical of the pathology. Data are available via ProteomeXchange with identifier PXD009440.

Significance: To date a single diagnostic test of multiple sclerosis does not exist, and diagnosis is based on multiple tests which mainly include the analysis of cerebrospinal fluid. However, the need for lumbar puncture makes the analysis of cerebrospinal fluid impractical for monitoring disease activity and response to treatment. The possible use of saliva as a diagnostic fluid for oral and systemic diseases has been largely investigated, but only marginally in multiple sclerosis compared to other body fluids. Our study demonstrates that the salivary proteome of multiple sclerosis patients differs considerably compared to that of sex and age matched healthy individuals and suggests that some differences might be associated with the different disease-modifying therapy used to treat multiple sclerosis patients.
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http://dx.doi.org/10.1016/j.jprot.2018.07.019DOI Listing
September 2018

Extensive Characterization of the Human Salivary Basic Proline-Rich Protein Family by Top-Down Mass Spectrometry.

J Proteome Res 2018 09 20;17(9):3292-3307. Epub 2018 Aug 20.

Department of Life and Environmental Sciences , University of Cagliari, Cittadella Univ. Monserrato , Monserrato 09042 , Cagliari , Italy.

Human basic proline-rich proteins and basic glycosylated proline-rich proteins, encoded by the polymorphic PRB1-4 genes and expressed only in parotid glands, are the most complex family of adult salivary proteins. The family includes 11 parent peptides/proteins and more than 6 parent glycosylated proteins, but a high number of proteoforms with rather similar structures derive from polymorphisms and post-translational modifications. 55 new components of the family were characterized by top-down liquid chromatography-mass spectrometry and tandem-mass platforms, bringing the total number of proteoforms to 109. The new components comprise the three variants P-H S → A, P-Ko P → S, and P-Ko A → S and several of their naturally occurring proteolytic fragments. The paper represents an updated reference for the peptides included in the heterogeneous family of proteins encoded by PRB1/PRB4. MS data are available via ProteomeXchange with the identifier PXD009813.
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http://dx.doi.org/10.1021/acs.jproteome.8b00444DOI Listing
September 2018

Cryptides: latent peptides everywhere.

Crit Rev Biochem Mol Biol 2018 06 22;53(3):246-263. Epub 2018 Mar 22.

c Dipartimento di Scienze della Vita e dell'Ambiente , Università di Cagliari , Cagliari , Italy.

Proteomic surveys with top-down platforms are today revealing thousands of naturally occurring fragments of bigger proteins. Some of them have not functional meaning because they derive from pathways responsible for protein degradation, but many have specific functions, often completely different from that one of the parent proteins. These peptides encrypted in the protein sequence are nowadays called cryptides. They are frequent in the animal and plant kingdoms and represent a new interesting -omic field of investigation. To point out how much widespread is their presence, we describe here the most studied cryptides from very common sources such as serum albumin, immunoglobulins, hemoglobin, and from saliva and milk proteins. Given its vastness, it is unfeasible to cover the topic exhaustively, therefore only several selected examples of cryptides from other sources are thereafter reported. Demanding is the development of new -omic platforms for the functional screening of new cryptides, which could provide suggestion for peptides and peptido-mimetics with variegate fields of application.
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http://dx.doi.org/10.1080/10409238.2018.1447543DOI Listing
June 2018

Marked Differences in the Submandibular Salivary Proteome between Sardinian Alcohol-Preferring and Sardinian Alcohol-Non Preferring Rats Revealed by an Integrated Top-Down-Bottom-Up Proteomic Platform.

J Proteome Res 2018 01 16;17(1):455-469. Epub 2017 Nov 16.

Istituto di Biochimica e Biochimica Clinica, Facoltà di Medicina, Università Cattolica , Largo Francesco Vito 1 00168, Rome, Italy.

Sardinian alcohol-preferring (sP) and Sardinian alcohol-non preferring (sNP) rats have been selectively bred for opposite alcohol preference and consumption. Aiming to verify possible differences at the proteomics level between sP and sNP rats, we investigated the salivary proteome by a a liquid chromatography-mass spectrometry top-down-bottom-up integrated approach. For this purpose, submandibular saliva was collected from alcohol-naive sP and sNP rats under isoprenaline stimulation. A total of 200 peptides and proteins were detected and quantified in the two rat lines, 149 of which were characterized in their naturally occurring structure. The data are available via ProteomeXchange with identifier PXD006997. Surprisingly, sP rats exhibited marked quantitative and qualitative differences with respect to sNP rats, namely higher levels of proteoforms originating from submandibular gland protein C, and from submandibular rat protein 2, as well as those of several unidentified peptides and proteins. sP rats expressed some proteins not detectable in sNP rats such as the glutamine and glutamic acid-rich protein (GRP)-CB. The isoform GRP-B, detectable in both rat lines, was more abundant in sNP rats. The submandibular saliva of sNP rats was also characterized by very high levels of GRP-B proteolytic peptides and rat salivary protein 1. Whether these differences could contribute to the opposite alcohol preference and consumption of sP and sNP rats is currently unknown and requires further investigation.
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http://dx.doi.org/10.1021/acs.jproteome.7b00632DOI Listing
January 2018

Salivary Cystatins: Exploring New Post-Translational Modifications and Polymorphisms by Top-Down High-Resolution Mass Spectrometry.

J Proteome Res 2017 11;16(11):4196-4207

Department of Life and Environmental Sciences, Biomedical Section, University of Cagliari , Monserrato Campus, 09042 Monserrato, Cagliari, Italy.

Cystatins are a complex family of cysteine peptidase inhibitors. In the present study, various proteoforms of cystatin A, cystatin B, cystatin S, cystatin SN, and cystatin SA were detected in the acid-soluble fraction of human saliva and characterized by a top-down HPLC-ESI-MS approach. Proteoforms of cystatin D were also detected and characterized by an integrated top-down and bottom-up strategy. The proteoforms derive from coding sequence polymorphisms and post-translational modifications, in particular, phosphorylation, N-terminal processing, and oxidation. This study increases the current knowledge of salivary cystatin proteoforms and provides the basis to evaluate possible qualitative/quantitative variations of these proteoforms in different pathological states and reveal new potential salivary biomarkers of disease. Data are available via ProteomeXchange with identifier PXD007170.
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http://dx.doi.org/10.1021/acs.jproteome.7b00567DOI Listing
November 2017

Profiles of VGF Peptides in the Rat Brain and Their Modulations after Phencyclidine Treatment.

Front Cell Neurosci 2017 2;11:158. Epub 2017 Jun 2.

Neuro-Endocrine-Fluorecence (NEF) Laboratory, Department of Biomedical Sciences, University of CagliariMonserrato, Italy.

From the VGF precursor protein originate several low molecular weight peptides, whose distribution in the brain and blood circulation is not entirely known. Among the VGF peptides, those containing the N-terminus portion were altered in the cerebro-spinal fluid (CSF) and hypothalamus of schizophrenia patients. "Hence, we aimed to better investigate the involvement of the VGF peptides in schizophrenia by studying their localization in the brain regions relevant for the disease, and revealing their possible modulations in response to certain neuronal alterations occurring in schizophrenia". We produced antibodies against different VGF peptides encompassing the N-terminus, but also C-terminus-, TLQP-, GGGE- peptide sequences, and the so named NERP-3 and -4. These antibodies were used to carry out specific ELISA and immunolocalization studies while mass spectrometry (MS) analysis was also performed to recognize the intact brain VGF fragments. We used a schizophrenia rat model, in which alterations in the prepulse inhibition (PPI) of the acoustic startle response occurred after PCP treatment. In normal rats, all the VGF peptides studied were distributed in the brain areas examined including hypothalamus, prefrontal cortex, hippocampus, accumbens and amygdaloid nuclei and also in the plasma. By liquid chromatography-high resolution mass, we identified different intact VGF peptide fragments, including those encompassing the N-terminus and the NERPs. PCP treatment caused behavioral changes that closely mimic schizophrenia, estimated by us as a disruption of PPI of the acoustic startle response. The PCP treatment also induced selective changes in the VGF peptide levels within certain brain areas. Indeed, an increase in VGF C-terminus and TLQP peptides was revealed in the prefrontal cortex ( < 0.01) where they were localized within parvoalbumin and tyrosine hydroxylase (TH) containing neurons, respectively. Conversely, in the nucleus accumbens, PCP treatment produced a down-regulation in the levels of VGF C-terminus-, N-terminus- and GGGE- peptides ( < 0.01), expressed in GABAergic- (C-terminus/GGGE) and somatostatin- (N-terminus) neurons. These results confirm that VGF peptides are widely distributed in the brain and modulated in specific areas involved in schizophrenia.
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http://dx.doi.org/10.3389/fncel.2017.00158DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5454051PMC
June 2017

Top-down HPLC-ESI-MS proteomic analysis of saliva of edentulous subjects evidenced high levels of cystatin A, cystatin B and SPRR3.

Arch Oral Biol 2017 May 31;77:68-74. Epub 2017 Jan 31.

Dipartimento di Scienze della Vita e dell'Ambiente, Università di Cagliari, 09042, Monserrato CA, Italy.

Objective: This study aims to analyze the salivary peptidome/proteome of edentulous subject with respect to dentate control subjects.

Design: Unstimulated whole saliva, collected from 11 edentulous subjects (age 60-76 years) and 11 dentate age-matched control subjects, was immediately treated with 0.2% aqueous trifluoroacetic acid and the acidic soluble fraction analyzed by High Performace Liquid Chromatography-Mass Spectrometry. The relative abundance of the salivary peptides/proteins was determined by measuring the area of the High Performace Liquid Chromatography-Mass Spectrometry eXtracted Ion Current peaks which is linearly proportional to peptide/protein concentration under identical experimental conditions. Levels of salivary peptides/proteins in the two groups were compared by the nonparametric Mann-Whitney test to evidence statistically significant differences.

Results: Levels of cystatin A, S-glutathionylated, S-cystenylated, S-S dimer derivatives of cystatin B and S-glutathionylated derivative of SPRR3, were found significantly higher in edentulous subjects with respect to dentate controls. The major peptides and proteins typically deriving from salivary glands did not show any statistically significant differences.

Conclusions: Cystatin A, S-glutathionylated, S-cystenylated, S-S dimer derivatives of cystatin B and S-glutathionylated derivative of SPRR3, which are mainly of intracellular origin and represent the major constituents of the cornified cell envelope are a clue of inflammation of mucosal epithelia.
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http://dx.doi.org/10.1016/j.archoralbio.2017.01.021DOI Listing
May 2017

Sensory perception of and salivary protein response to astringency as a function of the 6-n-propylthioural (PROP) bitter-taste phenotype.

Physiol Behav 2017 05 24;173:163-173. Epub 2017 Jan 24.

Department of Food Science and Center for Sensory Sciences & Innovation, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, NJ 08901-8520, USA. Electronic address:

Individual differences in astringency perception are poorly understood. Astringency from tannins stimulates the release of specific classes of salivary proteins. These proteins form complexes with tannins, altering their perceived astringency and reducing their bioavailability. We studied the bitter compound, 6-n-propylthioural (PROP), as a phenotypic marker for variation in astringency perception and salivary protein responses. Seventy-nine subjects classified by PROP taster status rated cranberry juice cocktail (CJC; with added sugar) supplemented with 0, 1.5 or 2.0g/L tannic acid (TA). Saliva for protein analyses was collected at rest, or after stimulation with TA or cranberry juice (CJ; without added sugar). CJC with 1.5g/L tannic acid was found to be less astringent, and was liked more by PROP non-taster males than PROP taster males, consistent with the expectation that non-tasters are less sensitive to astringency. Levels of acidic Proline Rich Proteins (aPRPs) and basic Proline Rich Proteins (bPRPs) decreased after TA, while levels of aPRPs, bPRPs and Cystatins unexpectedly rose after CJ. Increases in bPRPs and Cystatins were only observed in PROP tasters. The PROP phenotype plays a gender-specific, but somewhat limited role in the perceived astringency of tannic-acid supplemented, cranberry juice cocktail. The PROP phenotype (regardless of gender) may also be involved in the release of salivary proteins previously implicated in oral health.
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http://dx.doi.org/10.1016/j.physbeh.2017.01.031DOI Listing
May 2017

VGF Protein and Its C-Terminal Derived Peptides in Amyotrophic Lateral Sclerosis: Human and Animal Model Studies.

PLoS One 2016 13;11(10):e0164689. Epub 2016 Oct 13.

NEF-Laboratory, Department of Biomedical Sciences, University of Cagliari, Cagliari, Italy.

VGF mRNA is widely expressed in areas of the nervous system known to degenerate in Amyotrophic Lateral Sclerosis (ALS), including cerebral cortex, brainstem and spinal cord. Despite certain VGF alterations are reported in animal models, little information is available with respect to the ALS patients. We addressed VGF peptide changes in fibroblast cell cultures and in plasma obtained from ALS patients, in parallel with spinal cord and plasma samples from the G93A-SOD1 mouse model. Antisera specific for the C-terminal end of the human and mouse VGF proteins, respectively, were used in immunohistochemistry and enzyme-linked immunosorbent assay (ELISA), while gel chromatography and HPLC/ESI-MS/MS were used to identify the VGF peptides present. Immunoreactive VGF C-terminus peptides were reduced in both fibroblast and plasma samples from ALS patients in an advanced stage of the disease. In the G93A-SOD1 mice, the same VGF peptides were also decreased in plasma in the late-symptomatic stage, while showing an earlier down-regulation in the spinal cord. In immunohistochemistry, a large number of gray matter structures were VGF C-terminus immunoreactive in control mice (including nerve terminals, axons and a few perikarya identified as motoneurons), with a striking reduction already in the pre-symptomatic stage. Through gel chromatography and spectrometry analysis, we identified one form likely to be the VGF precursor as well as peptides containing the NAPP- sequence in all tissues studied, while in the mice and fibroblasts, we revealed also AQEE- and TLQP- peptides. Taken together, selective VGF fragment depletion may participate in disease onset and/or progression of ALS.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0164689PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5063282PMC
May 2017

Thymosin β and β in Sjögren's syndrome: saliva proteomics and minor salivary glands expression.

Arthritis Res Ther 2016 10 6;18(1):229. Epub 2016 Oct 6.

Division of Rheumatology, Fondazione Policlinico Universitario Agostino Gemelli, Rome, Italy.

Background: In the present study, we investigated whether thymosin β (Tβ) in saliva and in minor salivary glands is differentially expressed in patients with primary Sjögren's syndrome (pSS) and patients with autoimmune diseases (systemic sclerosis [SSc], systemic lupus erythematosus [SLE], and rheumatoid arthritis [RA], with and without sicca syndrome [ss]).

Methods: Saliva specimens of nine patients with pSS, seven with ss/SSc, seven with ss/SLE, seven with ss/RA, seven with SSc, seven with SLE, and seven with RA, as well as ten healthy subjects, were analyzed using a high-performance liquid chromatograph coupled with a mass spectrometer equipped with an electrospray ionization source to investigate the presence and levels of Tβ, Tβ sulfoxide, and Tβ. Immunostaining for Tβ and Tβ was performed on minor salivary glands of patients with pSS and ss.

Results: Tβ levels were statistically higher in patients with pSS with respect to the other subgroups. Tβ was detectable in 66.7 % of patients with pSS and in 42.8 % of those with ss/SSc, while Tβ sulfoxide was detectable in 44.4 % of patients with pSS and in 42.9 % of those with ss/SSc. Tβ and Tβ sulfoxide were not detectable in patients without associated ss and in healthy control subjects. Regarding thymosin immunostaining, all patients had immunoreactivity for Tβ, and a comparable distribution pattern in the four different subgroups of patients was observed. Tβ immunoreactivity was present in patients with ss/SSc and those with ss/SLE, while it was completely absent in patients with pSS and those with ss/RA.

Conclusions: Our data show that higher salivary Tβ expression characterizes patients with pSS, while Tβ sulfoxide and Tβ salivary expression was selectively present in patients with sicca symptoms. Moreover, at the immunohistochemical level in patients with pSS, minor salivary glands showed a peculiar pattern characterized by immunostaining for Tβ in acinar cells in the absence of any reactivity for Tβ. These findings, taken together, suggest a different role for Tβ and Tβ in patients with pSS who have ss and other autoimmune disease.
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http://dx.doi.org/10.1186/s13075-016-1134-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5053072PMC
October 2016

Proteomics applied to pediatric medicine: opportunities and challenges.

Expert Rev Proteomics 2016 09 25;13(9):883-94. Epub 2016 Aug 25.

b Istituto di Chimica del Riconoscimento Molecolare - UOS Roma , Consiglio Nazionale delle Ricerche , Rome , Italy.

Introduction: Care in pediatrics often refers to treatments directed to adults. However, childhood is a specific life period, with molecular pathways connected to development and thereby it requires distinctive considerations and special treatments under disease. Proteomics can help to elucidate the molecular mechanisms underlying the human development and disease onset in pediatric age and this review is devoted to underline the results recently obtained in the field.

Areas Covered: The contribution of proteomics to the characterization of physiological modifications occurring during human development is presented. The proteomic studies carried out to elucidate the molecular mechanisms underlying different pediatric pathologies and to discover new markers for early diagnosis and prognosis of disease, comprising genetic and systemic pathologies, sepsis and pediatric oncology are thereafter reported. The investigations concerning milk composition in human and farm mammals are also presented. Finally, the chances offered by the integration of different -omic platforms are discussed. Expert commentary: The growing utilization of holistic technologies such as proteomics, metabolomics and microbiomics will allow, in the near future, to define at the molecular level the complexity of human development and related diseases, with great benefit for future generations.
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http://dx.doi.org/10.1080/14789450.2016.1221764DOI Listing
September 2016

Proteomic characterization of the acid-insoluble fraction of whole saliva from preterm human newborns.

J Proteomics 2016 09 16;146:48-57. Epub 2016 Jun 16.

Department of Life and Environmental Sciences, Biomedical Section, University of Cagliari, Monserrato Campus, 09042 Monserrato, CA, Italy. Electronic address:

The acid-insoluble salivary proteome obtained by addition of TFA to whole human saliva from adults, preterm and at-term newborns has been analysed by 2-DE in order to evidence differences among the three groups, and integrate data previously obtained on the acid-soluble fraction. 2-DE spots differentially expressed among the three groups were submitted to in-gel tryptic digestion and the peptide mixtures analysed by high resolution HPLC–ESI–MS/MS. By this strategy, we identified 3 over-expressed proteins in at-term newborns with respect to preterm newborns and adults (BPI fold-containing family A member 1, annexin A1, and keratin type 1 cytoskeletal 13), and several over-expressed proteins in adults (fatty acid-binding protein, S100 A6, S100 A7, S100 A9, prolactin-inducible protein, Ig kappa chain, cystatin SN, cystatin S/SA and α-amylase 1). Four spots, already detected but not characterized by other authors in human saliva 2-DE, were attributed to different protein species of S100 A9 (long-type and long-type monophosphorylated, short-type and short-type monophosphorylated) by MS/MS analysis of tryptic peptides and sequential staining of 2-DE gels with Pro-Q Diamond, for specific detection of phosphoproteins, and total protein SYPRO Ruby stain.

Significance: Differential protein expression analysis of the acid insoluble fraction of saliva from preterm, at-term newborns and adults has been performed in this study by coupling 2-DE analysis and high-resolution tandem mass spectrometry in order to complete the information previously obtained by top-down LC–MS only on the acid-soluble proteome. Several proteins identified in the acid insoluble fraction of both preterm newborn and adult saliva are not of glandular origin, being only prolactin-inducible protein, salivary cystatins, α-amylase and polymeric immunoglobulin receptor exclusive of salivary glands. Three proteins resulted increased in at-term newborns with respect to preterm newborns and adults: BPI fold-containing family A member 1, two proteoforms of annexin A1 and keratin type 1 cytoskeletal 13, while several proteins were significantly increased in adults.
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http://dx.doi.org/10.1016/j.jprot.2016.06.021DOI Listing
September 2016

Structural studies and SH3 domain binding properties of a human antiviral salivary proline-rich peptide.

Biopolymers 2016 Sep;106(5):714-25

Istituto di Chimica di Riconoscimento Molecolare, C.N.R. Rome, L.Go F. Vito, 1, Rome, 00168, Italy.

Human saliva contains hundreds of small proline-rich peptides originated by the proteolytic cleavage of the salivary basic Proline-Rich Proteins. Nevertheless only for few of them a specific biological activity has been assigned to date. Among them, the 1932 Da peptide (p1932) has been patented as an anti-HIV agent. In order to shed light on the possible mechanism of action of this peptide, we assessed in this study, by means of molecular dynamics calculations, circular dichroism and FTIR spectroscopic techniques, that p1932 has an intrinsic propensity to adopt a polyproline-II helix arrangement. This structural feature combined with the presence of PxxP motifs in its primary structure, represents an essential property for the exploitation of several biological activities. Next to these findings, we recently demonstrated the ability of this peptide to be internalized within cells of the oral mucosa, thus we focused onto a possible intracellular target, represented by the SH3 domains family. Its ability to interact with selected SH3 domains was finally assayed by Surface Plasmon Resonance spectroscopy. As a result, only Fyn, Hck, and c-Src SH3 domains gave positive results in terms of interaction, showing dissociation constants ranging from nanomolar to micromolar values having the best performer a KD of 148 nM. It is noteworthy that all the interacting domains belong to the Src kinases family, suggesting a role for p1932 as a modulator of the signal transduction pathways mediated by these kinases. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 714-725, 2016.
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http://dx.doi.org/10.1002/bip.22889DOI Listing
September 2016

Characterization of the Protein Components of Matrix Stones Sheds Light on S100-A8 and S100-A9 Relevance in the Inflammatory Pathogenesis of These Rare Renal Calculi.

J Urol 2016 Sep 23;196(3):911-8. Epub 2016 Apr 23.

Nephrology Division, Institute of Internal Medicine, Catholic University, Rome, Italy. Electronic address:

Purpose: Among the different types of kidney stones, matrix stones are uncommon urinary calculi composed of a soft, pliable, amorphous substance with little crystalline content. To gain insight into the pathogenesis we investigated the protein component by analyzing the proteomic profiles of surgically removed matrix stones.

Materials And Methods: A total of 5 stones were harvested from 4 patients who underwent surgery for medical reasons at 3 clinical centers during a 7-year period. Matrix stone proteome characterization was performed by mass spectrometry based techniques using an integrated top-down/bottom-up proteomic platform.

Results: We identified 142 nonredundant proteins and peptides across all samples. Neutrophil defensin 1, and proteins S100-A8 and S100-A9 were the main components of these renal calculi.

Conclusions: The abundance of identified inflammatory molecules points to an inflammatory process as the event that initializes soft calculi formation rather than as a consequence of such formation. The post-translational oxidative changes in S100-A8 and A9, and the presence of thymosin β-4, granulins and ubiquitin also suggest the intervention of host defenses through a superimposed, vigorous counter inflammatory process. The post-translational changes seen in the proteins and peptides, and the known self-assembling capability of S100-A8 and S100-A9 probably explain the gelatinous consistency of these stones.
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http://dx.doi.org/10.1016/j.juro.2016.04.064DOI Listing
September 2016

Top-down proteomic characterization of DAOY medulloblastoma tumor cell line.

EuPA Open Proteom 2016 Sep 1;12:13-21. Epub 2016 Apr 1.

Istituto di Chimica del Riconoscimento Molecolare, Consiglio Nazionale delle Ricerche, Rome, Italy.

The proteome of the DAOY medulloblastoma cell line has been investigated by an LC-MS top-down platform. This approach, unlike bottom-up ones, allows identifying proteins and peptides in their intact/native forms, disclosing post-translational modifications, proteoforms and naturally occurring peptides. Indeed, 25 out of the 53 proteins identified, were not previously characterized in DAOY cells. Most of them were functionally interconnected, being mainly involved in binding, catalytic and structural activities, and metabolic processes. The top-down approach, applied in this preliminary study, disclosed the presence of several naturally occurring peptide fragments that characterize DAOY cells.
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http://dx.doi.org/10.1016/j.euprot.2016.03.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5988510PMC
September 2016

N- and O-linked glycosylation site profiling of the human basic salivary proline-rich protein 3M.

J Sep Sci 2016 May 29;39(10):1987-97. Epub 2016 Apr 29.

Istituto di Chimica del Riconoscimento Molecolare - CNR, Roma, Italy.

In the present study, we show that the heterogeneous mixture of glycoforms of the basic salivary proline-rich protein 3M, encoded by PRB3-M locus, is a major component of the acidic soluble fraction of human whole saliva in the first years of life. Reversed-phase high-performance liquid chromatography with high-resolution electrospray ionization mass spectrometry analysis of the intact proteoforms before and after N-deglycosylation with Peptide-N-Glycosidase F and tandem mass spectrometry sequencing of peptides obtained after Endoproteinase GluC digestion allowed the structural characterization of the peptide backbone and identification of N- and O-glycosylation sites. The heterogeneous mixture of the proteoforms derives from the combination of 8 different neutral and sialylated glycans O-linked to Threonine 50, and 33 different glycans N-linked to Asparagine residues at positions 66, 87, 108, 129, 150, 171, 192, and 213.
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http://dx.doi.org/10.1002/jssc.201501306DOI Listing
May 2016

Antagonistic Effect of a Salivary Proline-Rich Peptide on the Cytosolic Ca2+ Mobilization Induced by Progesterone in Oral Squamous Cancer Cells.

PLoS One 2016 27;11(1):e0147925. Epub 2016 Jan 27.

Istituto per la Chimica del Riconoscimento Molecolare, Italian National Research Council, Rome, UoS Rome, Italy.

A salivary proline-rich peptide of 1932 Da showed a dose-dependent antagonistic effect on the cytosolic Ca2+ mobilization induced by progesterone in a tongue squamous carcinoma cell line. Structure-activity studies showed that the activity of the peptide resides in the C-terminal region characterized by a proline stretch flanked by basic residues. Furthermore, lack of activity of the retro-inverso peptide analogue suggested the involvement of stereospecific recognition. Mass spectrometry-based shotgun analysis, combined with Western blotting tests and biochemical data obtained with the Progesterone Receptor Membrane Component 1 (PGRMC1) inhibitor AG205, showed strong evidence that p1932 performs its modulatory action through an interaction with the progesterone receptor PGRMC1, which is predominantly expressed in this cell line and, clearly, plays a role in progesterone induced Ca2+ response. Thus, our results point to p1932 as a modulator of the transduction signal pathway mediated by this protein and, given a well-established involvement of PGRMC1 in tumorigenesis, highlight a possible therapeutic potential of p1932 for the treatment of oral cancer.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0147925PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4729474PMC
July 2016

VGF Peptide Profiles in Type 2 Diabetic Patients' Plasma and in Obese Mice.

PLoS One 2015 12;10(11):e0142333. Epub 2015 Nov 12.

Department of Biomedical Sciences, University of Cagliari, 09042, Monserrato, Italy.

To address the possible involvement of VGF peptides in obesity and diabetes, we studied type 2 diabetes (T2D) and obese patients, and high-fat diet induced obese mice. Two VGF peptides (NAPP-19 and QQET-30) were identified in human plasma by HPLC-ESI-MS. The VGF C-terminus, the above two cleaved peptides, and the TLQP-21 related peptide/s were studied using ELISA and immunohistochemistry. In euglycemic patients, plasma NAPPE and TLQP like peptides were significantly reduced with obesity (74±10 vs. 167±28, and 92±10 vs. 191±19 pmol/ml, mean+SEM, n = 10 and 6, obese vs. normal BMI, respectively, p<0.03). Upon a standard glucose load, a distinct response was shown for VGF C-terminus, TLQP and QQET-like (ERVW immunoreactive) peptides in euglycemic normal BMI patients, but was virtually abolished in euglycemic obese, and in T2D patients independently of BMI. High-fat diet induced obese mice showed reduced plasma VGF C-terminus, NAPPE and QQET-like (ERVW) peptide/s (3±0.2 vs. 4.6±0.3, 22±3.5 vs. 34±1.3, and 48±7 vs. 100±7 pmol/ml, mean+SEM, n = 8/group, obese vs. slim, respectively, p<0.03), with a loss of the response to glucose for all VGF peptides studied. In immunohistochemistry, TLQP and/or VGF C-terminus antibodies labelled VGF containing perikarya in mouse celiac ganglia, pancreatic islet cells and thin beaded nerve fibres in brown adipose tissues, with fewer in white adipose tissue. Upon the glucose load, tyrosine hydroxylase and VGF C-terminus immunoreactive axons became apparent in pancreatic islets of slim animals, but not in obese animals. Alltogether, a significant loss of VGF peptide immunoreactivity and/or their response to glucose was demonstrated in obese patients, with or without T2D, in parallel with a similar loss in high-fat diet induced obese mice. An involvement of VGF in metabolic regulations, including those of brown and/or white adipose tissues is underlined, and may point out specific VGF peptides as potential targets for diagnosis and/or treatment.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0142333PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4643017PMC
June 2016

Photoperiod Regulates vgf-Derived Peptide Processing in Siberian Hamsters.

PLoS One 2015 10;10(11):e0141193. Epub 2015 Nov 10.

NEF-Laboratory, Dept. of Biomedical Sciences, University of Cagliari, Monserrato (CA), Italy.

VGF mRNA is induced in specific hypothalamic areas of the Siberian hamster upon exposure to short photoperiods, which is associated with a seasonal decrease in appetite and weight loss. Processing of VGF generates multiple bioactive peptides, so the objective of this study was to determine the profile of the VGF-derived peptides in the brain, pituitary and plasma from Siberian hamsters, and to establish whether differential processing might occur in the short day lean state versus long day fat. Antisera against short sequences at the C- or N- termini of proVGF, as well as against NERP-1, TPGH and TLQP peptides, were used for analyses of tissues, and both immunohistochemistry and enzyme linked immunosorbent assay (ELISA) coupled with high-performance liquid (HPLC) or gel chromatography were carried out. VGF peptide immunoreactivity was found within cortex cholinergic perikarya, in multiple hypothalamic nuclei, including those containing vasopressin, and in pituitary gonadotrophs. ELISA revealed that exposure to short day photoperiod led to a down-regulation of VGF immunoreactivity in the cortex, and a less pronounced decrease in the hypothalamus and pituitary, while the plasma VGF levels were not affected by the photoperiod. HPLC and gel chromatography both confirmed the presence of multiple VGF-derived peptides in these tissues, while gel chromatography showed the presence of the VGF precursor in all tissues tested except for the cortex. These observations are consistent with the view that VGF-derived peptides have pleiotropic actions related to changing photoperiod, possibly by regulating cholinergic systems in the cortex, vasopressin hypothalamic pathways, and the reproductive axis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0141193PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4640585PMC
June 2016

The intriguing heterogeneity of human salivary proline-rich proteins: Short title: Salivary proline-rich protein species.

J Proteomics 2016 Feb 14;134:47-56. Epub 2015 Sep 14.

Department of Life and Environmental Sciences, Biomedical section, University of Cagliari, Cagliari Italy. Electronic address:

Unlabelled: The most heterogeneous family of human salivary proteins is represented by proline-rich proteins (PRPs) divided in acidic, basic, and basic glycosylated (aPRPs, bPRPs, gPRPs). They are encoded by six genes, clustered on chromosome 12p13.2: PRH1-2 encode aPRPs, PRB1-4 encode bPRPs and gPRPs. Each gene exists in different allelic forms: two for PRH2, three for PRH1, PRB2, and PRB4, four for PRB1, and PRB3. During granule maturation, PRP proproteins undergo proteolysis by the action of convertases and carboxypeptidases. Differently from bPRPs, proteolysis of aPRPs is not complete, and, besides fragments, entire protein species are also secreted. Maturation process generates ten aPRPs (PRP-1, PRP-2, PIF-s, Db-s, Pa, PRP-3, PRP-4, PIF-f, Db-f, P-C), and at least 18 bPRPs (II-2, P-E, IB-6, Ps-1, Ps-2, IB-1, P-J, IB-8a, P-F, P-H, P-D, II-1, protein glycosylated A, CD-IIg, and Gl1-4). In addition, single nucleotide and length polymorphisms, and differentially spliced transcripts originate several natural variants. Phosphorylation, N-pyroglutaminylation, dimerization, and N-/O-glycosylation also occur during maturation, enlarging the number of protein species, further increased by proteolytic events governed by carboxy- and endo-peptidases during and after secretion, and giving rise to a huge number of small peptides. The PRP functional role is still poorly understood.

Significance: The high polymorphism of PRPs gives an important contribution to the high heterogeneity and inter-individual variability of the human salivary proteome. The products of six genes clustered on chromosome 12p13.2 comprise a mixture of entire, truncated, phosphorylated, glycosylated and dimerized protein/peptide species, sharing large part of their sequences, and possibly involved in different biological activities. Whatever the role of PRP species is, it should be crucial, given that PRPs are the most conserved oral salivary proteins among mammals.
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http://dx.doi.org/10.1016/j.jprot.2015.09.009DOI Listing
February 2016

Characterization of the cell penetrating properties of a human salivary proline-rich peptide.

Biochim Biophys Acta 2015 Nov 29;1848(11 Pt A):2868-77. Epub 2015 Aug 29.

Istituto per la Chimica del Riconoscimento Molecolare, Italian National Research Council, Rome, L. go F. Vito, 1, 00168 Rome, Italy. Electronic address:

Saliva contains hundreds of small proline-rich peptides most of which derive from the post-translational and post-secretory processing of the acidic and basic salivary proline-rich proteins. Among these peptides we found that a 20 residue proline-rich peptide (p1932), commonly present in human saliva and patented for its antiviral activity, was internalized within cells of the oral mucosa. The cell-penetrating properties of p1932 have been studied in a primary gingival fibroblast cell line and in a squamous cancer cell line, and compared to its retro-inverso form. We observed by mass-spectrometry, flow cytometry and confocal microscopy that both peptides were internalized in the two cell lines on a time scale of minutes, being the natural form more efficient than the retro-inverso one. The cytosolic localization was dependent on the cell type: both peptide forms were able to localize within nuclei of tumoral cells, but not in the nuclei of gingival fibroblasts. The uptake was shown to be dependent on the culture conditions used: peptide internalization was indeed effective in a complete medium than in a serum-free one allowing the hypothesis that the internalization could be dependent on the cell cycle. Both peptides were internalized likely by a lipid raft-mediated endocytosis mechanism as suggested by the reduced uptake in the presence of methyl-ß-cyclodextrin. These results suggest that the natural peptide may play a role within the cells of the oral mucosa after its secretion and subsequent internalization. Furthermore, lack of cytotoxicity of both peptide forms highlights their possible application as novel drug delivery agents.
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http://dx.doi.org/10.1016/j.bbamem.2015.08.019DOI Listing
November 2015