Proteomics of Human Teeth and Saliva

Evaluation of method parameters for sound undecalcified dental enamel proteomics using liquid chromatography-mass spectrometry

OBJECTIVE

This study aims to validate a methodology for analyzing undecalcified, sound dental enamel proteomics using Liquid Chromatography-Mass Spectrometry (LC-MS). The study evaluates various parameters, including the impact of dental root coverage on protein contamination, the efficacy of protease inhibitors during enamel sample preparation, repeatability of LC-MS measurements on dental enamel, and statistical analysis. The study also assesses the effectiveness of combined trypsin and semi-trypsin searches in Mascot for obtaining additional protein identification data.

DESIGN

Sound dental enamel was removed using a wet grinding technique, then digested with trypsin and labeled with TMT prior to LC-MS analysis. The resulting proteomes were matched against the Homo sapiens Swissprot Database, with searches in Mascot performed using both trypsin and semitrypsin. Statistical methods were employed to analyze the data.

RESULTS

The study found that covering dental roots with composite during dental enamel microdissection is advisable, while using protease inhibition during microdissection may not be fully supported. The proteomic analyses demonstrated statistical repeatability and reliability, with consistent and reproducible proteomic data obtained from healthy dental enamel. Furthermore, employing both trypsin and semitrypsin searches in Mascot provided additional proteomic information.

CONCLUSIONS

Overall, this study validates a methodology for analyzing undecalcified, sound dental enamel proteomics using LC-MS, and provides insights into various factors that can affect the quality and reliability of proteomic data. These findings have implications for future studies pursuant to understanding the proteomic mechanisms underlying dental enamel formation and other associated processes.

Establishing protein expression profiles involved in tooth development using a proteomic approach

Various growth and transcription factors are involved in tooth development and developmental abnormalities; however, the protein dynamics do not always match the mRNA expression level. Using a proteomic approach, this study comprehensively analyzed protein expression in epithelial and mesenchymal tissues of the tooth germ during development. First molar tooth germs from embryonic day 14 and 16 Crlj:CD1 (ICR) mouse embryos were collected and separated into epithelial and mesenchymal tissues by laser microdissection. Mass spectrometry of the resulting proteins was carried out, and three types of highly expressed proteins [ATP synthase subunit beta (ATP5B), receptor of activated protein C kinase 1 (RACK1), and calreticulin (CALR)] were selected for immunohistochemical analysis. The expression profiles of these proteins were subsequently evaluated during all stages of amelogenesis using the continuously growing incisors of 3-week-old male ICR mice. Interestingly, these three proteins were specifically expressed depending on the stage of amelogenesis. RACK1 was highly expressed in dental epithelial and mesenchymal tissues during the proliferation and differentiation stages of odontogenesis, except for the pigmentation stage, whereas ATP5B and CALR immunoreactivity was weak in the enamel organ during the early stages, but became intense during the maturation and pigmentation stages, although the timing of the increased protein expression was different between the two. Overall, RACK1 plays an important role in maintaining the cell proliferation and differentiation in the apical end of incisors. In contrast, ATP5B and CALR are involved in the transport of minerals and the removal of organic materials as well as matrix deposition for CALR.

Spatial analysis of the ancient proteome of archeological teeth using mass spectrometry imaging

RATIONALE

Proteins extracted from archaeological bone and teeth are utilised for investigating the phylogeny of extinct and extant species, the biological sex and age of past individuals, as well as ancient health and physiology. However, variable preservation of proteins in archaeological materials represents a major challenge.

METHODS

To better understand the spatial distribution of ancient proteins preserved within teeth, we applied matrix assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI) for the first time to bioarchaeological samples to visualise the intensity of proteins in archaeological teeth thin sections. We specifically explored the spatial distribution of four proteins (collagen type I, of which the chains alpha-1 and alpha-2, alpha-2-HS-glycoprotein, haemoglobin subunit alpha and myosin light polypeptide 6).

RESULTS

We successfully identified ancient proteins in archaeological teeth thin sections using mass spectrometry imaging. The data are available via ProteomeXchange with identifier PXD038114. However, we observed that peptides did not always follow our hypotheses for their spatial distribution, with distinct differences observed in the spatial distribution of several proteins, and occasionally between peptides of the same protein.

CONCLUSIONS

While it remains unclear what causes these differences in protein intensity distribution within teeth, as revealed by MALDI-MSI in this study, we have demonstrated that MALDI-MSI can be successfully applied to mineralised bioarchaeological tissues to detect ancient peptides. In future applications, this technique could be particularly fruitful not just for understanding the preservation of proteins in a range of archaeological materials, but making informed decisions on sampling strategies and the targeting of key proteins of archaeological and biological interest.

Applications of Mass Spectrometry in Dentistry

Mass Spectrometry (MS) is one of the fastest-developing methods in analytical instrumentation. As a highly sensitive, universal detector, it can identify known and unknown compounds, which can indeed be found in a minimal concentration. This review aims to highlight the significant milestones in MS applications in dentistry during recent decades. MS can be applied in three different fields of dentistry: (1) in research of dental materials and chemical agents, (2) in laboratory analysis of biospecimens, and (3) as a real-time diagnostic tool in service of oral surgery and pathology. MS applications on materials and agents may focus on numerous aspects, such as their clinical behavior, possible toxicity, or antimicrobial properties. MS is also a valuable, non-invasive tool for biomarkers' detection in saliva and has found great application in -omics technologies as it achieves efficient structure-finding in metabolites. As metabolites are located beyond the central dogma, this technique can provide a complete understanding of cellular functions. Thus, it is possible to determine the biological profile in normal and pathological conditions, detect various oral or systematic diseases and conditions, and predict their course. Lastly, some promising advances concerning the surgical approach to potentially oral malignant or malignant disorders exist. This breakthrough method provides a comprehensive approach to dental materials research and biomarker discovery in dental and craniofacial tissues. The current availability of various 'OMIC' approaches paves the way for individualized dentistry and provides suggestions for clinical applications in the point-of-care hubs.

Proteomic Analysis in Nifedipine Induced Gingival Overgrowth: A Pilot Study

Objective: The aims of the present study were to investigate the proteomic profile of nifedipine induced overgrown gingiva and compare with non-overgrown gingival tissues obtained from the same patients. Methods: Seven subjects under nifedipine medication for at least 6 months and diagnosed as nifedipine induced gingival overgrowth (NIGO) participated in the study. Periodontal clinical parameters were recorded. Gingival tissue samples were harvested from overgrown (GO+ Group, n=7) and non-overgrown regions (GO- Group, n=7) of the same patients. Proteomics was performed using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) technique. The identified proteins were further classified according to their molecular functions, biological processes and cellular component distribution for functional gene ontology analysis using a web-based bioinformatics tool. Mann Whitney-U and ANOVA tests were performed to compare clinical parameters and identified proteins with proteomics, respectively. Results: Bleeding on probing and gingival overgrowth index of the GO+ group were statistically significantly higher than the GO- group (p

Complementing the pulp proteome via sampling with a picosecond infrared laser (PIRL)

OBJECTIVES

The aim of this investigation was the detailed analysis of the human pulp proteome using the new picosecond infrared laser (PIRL)-based sampling technique, which is based on a completely different mechanism compared to mechanical sampling. Proteome analysis of healthy pulp can provide data to define changes in the proteome associated with dental disease.

MATERIAL AND METHODS

Immediately after extraction of the entire, undamaged tooth, 15 wisdom teeth were deep frozen in liquid nitrogen and preserved at -80°C. Teeth were crushed, and the excised frozen pulps were conditioned for further analysis. The pulps were sampled using PIRL, and the aspirates digested with trypsin and analyzed with mass spectrometry. Pulp proteins were categorized according to their gene ontology terminus. Proteins identified exclusively in this study were searched in the Human Protein Atlas (HPA) for gaining information about the main known localization and function.

RESULTS

A total of 1348 proteins were identified in this study. The comparison with prior studies showed a match of 72%. Twenty-eight percent of the proteins were identified exclusively in this study. Considering HPA, almost half of these proteins were assigned to tissues that could be pulp specific.

CONCLUSION

PIRL is releasing proteins from the dental pulp which are not dissolved by conventional sampling techniques. Clinical Relevance The presented data extend current knowledge on dental pulp proteomics in healthy teeth and can serve as a reference for studies on pulp proteomics in dental disease.

Metaproteome and metabolome of oral microbial communities

The emergence of high-throughput technologies for the comprehensive measurement of biomolecules, also referred to as "omics" technologies, has helped us gather "big data" and characterize microbial communities. In this article, we focus on metaproteomic and metabolomic approaches that support hypothesis-driven investigations on various oral biologic samples. Proteomics reveals the working units of the oral milieu and metabolomics unveils the reactions taking place; and so these complementary techniques can unravel the functionality and underlying regulatory processes within various oral microbial communities. Current knowledge of the proteomic interplay and metabolic interactions of microorganisms within oral biofilm and salivary microbiome communities is presented and discussed, from both clinical and basic research perspectives. Communities indicative of, or from, health, caries, periodontal diseases, and endodontic lesions are represented. Challenges, future prospects, and examples of best practice are given.

Protein sequence comparison of human and non-human primate tooth proteomes

In the context of human evolution, the study of proteins may overcome the limitation of the high degradation of ancient DNA over time to provide biomolecular information useful for the phylogenetic reconstruction of hominid taxa. In this study, we used a shotgun proteomics approach to compare the tooth proteomes of extant human and non-human primates (gorilla, chimpanzee, orangutan and baboon) in order to search for a panel of peptides able to discriminate between taxa and further help reconstructing the evolutionary relationships of fossil primates. Among the 25 proteins shared by the five genera datasets, we found a combination of peptides with sequence variations allowing to differentiate the hominid taxa in the proteins AHSG, AMBN, APOA1, BGN, C9, COL11A2, COL22A1, COL3A1, DSPP, F2, LUM, OMD, PCOLCE and SERPINA1. The phylogenetic tree confirms the placement of the samples in the appropriate genus branches. Altogether, the results provide experimental evidence that a shotgun proteomics approach on dental tissue has the potential to detect taxonomic variation, which is promising for future investigations of uncharacterized and/or fossil hominid/hominin specimens. SIGNIFICANCE: A shotgun proteomics approach on human and non-human primate teeth allowed to identify peptides with taxonomic interest, highlighting the potential for future studies on hominid fossils.

Mapping the Inorganic and Proteomic Differences among Different Types of Human Teeth: A Preliminary Compositional Insight

In recent years, studies on mineralized tissues are becoming increasingly popular not only due to the diverse mechanophysical properties of such materials but also because of the growing need to understand the intricate mechanism involved in their assembly and formation. The biochemical mechanism that results in the formation of such hierarchical structures through a well-coordinated accumulation of inorganic and organic components is termed biomineralization. Some prime examples of such tissues in the human body are teeth and bones. Our current study is an attempt to dissect the compositional details of the inorganic and organic components in four major types of human teeth using mass spectrometry-based approaches. We quantified inorganic materials using inductively coupled plasma resonance mass spectrometry (ICP-MS). Differential level of ten different elements, Iron (Fe), Cadmium (Cd), Potassium (K), Sulphur (S), Cobalt (Co), Magnesium (Mg), Manganese (Mn), Zinc (Zn), Aluminum (Al), and Copper (Cu) were quantified across different teeth types. The qualitative and quantitative details of their respective proteomic milieu revealed compositional differences. We found 152 proteins in total tooth protein extract. Differential abundance of proteins in different teeth types were also noted. Further, we were able to find out some significant protein-protein interaction (PPI) backbone through the STRING database. Since this is the first study analyzing the differential details of inorganic and organic counterparts within teeth, this report will pave new directions to the compositional understanding and development of novel in-vitro repair strategies for such biological materials.

Equivalence of human and bovine dentin matrix molecules for dental pulp regeneration: proteomic analysis and biological function

OBJECTIVE

To compare proteomics and biological function of human dentin matrix molecules (hDMMs) and bovine dentin matrix molecules (bDMMs).

DESIGN

Dentin powder from human or bovine teeth (n = 4) was demineralized in 10% (v/v) ethylenediaminetetraacetic acid for 7 days. The extracts were dialyzed, lyophilized and proteins were characterized using liquid chromatography-tandem mass spectrometry and shotgun proteomic analysis. To study biological function, mouse-derived undifferentiated dental pulp cells (OD21) were treated with 0.01, 0.1 or 1 μg/mL of hDMMs or bDMMs and proliferation was measured after 24 hours and 48 hours using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell migration was assessed after 24 hours using a Boyden chamber. Alizarin Red S staining was used to evaluate mineral formation.

RESULTS

There were 307 proteins identified, of which 93 proteins were common to both species. Gene Ontology functional analysis demonstrated similar pattern of biological process in both species which consisted mainly of tissue development and biomineralization. hDMMs and bDMMs both enhanced cell proliferation. After 24 hours, all concentrations of bDMMs promoted cell proliferation (p ≤ 0.05), while hDMMs did not affect proliferation. After 48 hours, groups with 1μg/mL of bDMMs and 0.01μg/mL of hDMMs had increased cell proliferation compared to control (p ≤ 0.0001). All concentrations of hDMMs and bDMMs enhanced cell migration and mineralization (p ≤ 0.0001).

CONCLUSION

bDMMs has similar biological functions as hDMMs. Moreover, bDMMs stimulated cell proliferation, migration and differentiation similar to hDMMs.

Analysis of 5000 year-old human teeth using optimized large-scale and targeted proteomics approaches for detection of sex-specific peptides

The study demonstrates the high potential of MS-based proteomics coupled to an iterative database search strategy for the in-depth investigation of ancient proteomes. An efficient targeted PRM MS-based approach, although limited to the detection of a single pair of sex-specific amelogenin peptides, allowed confirming the sex of individuals in ancient dental remains, an essential information for paleoanthropologists facing the issue of sex determination and dimorphism.

Clinical efficacy of sublingual immunotherapy tablets for allergic rhinitis is unlikely to be derived from in vitro allergen-release data

Introduction: Allergen bioavailability underpins the efficacy and safety of SLIT tablets. Three product-related factors are likely to influence this: tablet potency, formulation and sublingual holding time. Areas covered: Tablet formulation determines the rate and extent of solubilized allergen release. Using validated in vitro dissolution assays, the two licensed grass pollen SLIT tablets are shown to release ≥85% of their total allergenic activity within several minutes. Sublingual holding time affects the contact duration between solubilized allergens and sublingual tissue. Maximal uptake of allergens by sublingual tissue requires ~5 minutes, with little uptake occurring within the first minute. A higher potency tablet with longer sublingual holding time would provide higher bioavailability, while faster rates of allergen release in vitro are unlikely to translate to a greater increase in bioavailability. Differences in dissolution times cannot serve as a surrogate of in vivo bioavailability, and are not related to differences in efficacy at the marketed tablet dosages. Rapid in vitro dissolution is likely not a key requirement for inducing a potent immune response. Expert opinion: In vitro dissolution cannot predict the clinical efficacy of SLIT tablets but could be important in immune tolerance and safety. In addition, a discontinuous administration regimen may have benefits for adherence and cost without compromising efficacy.

Mapping the Tooth Enamel Proteome and Amelogenin Phosphorylation Onto Mineralizing Porcine Tooth Crowns

Tooth enamel forms in an ephemeral protein matrix where changes in protein abundance, composition and posttranslational modifications are critical to achieve healthy enamel properties. Amelogenin (AMELX) with its splice variants is the most abundant enamel matrix protein, with only one known phosphorylation site at serine 16 shown in vitro to be critical for regulating mineralization. The phosphorylated form of AMELX stabilizes amorphous calcium phosphate, while crystalline hydroxyapatite forms in the presence of the unphosphorylated protein. While AMELX regulates mineral transitions over space and time, it is unknown whether and when un-phosphorylated amelogenin occurs during enamel mineralization. This study aims to reveal the spatiotemporal distribution of the cleavage products of the most abundant AMLEX splice variants including the full length P173, the shorter leucine-rich amelogenin protein (LRAP), and the exon 4-containing P190 in forming enamel, all within the context of the changing enamel matrix proteome during mineralization. We microsampled permanent pig molars, capturing known stages of enamel formation from both crown surface and inner enamel. Nano-LC-MS/MS proteomic analyses after tryptic digestion rendered more than 500 unique protein identifications in enamel, dentin, and bone. We mapped collagens, keratins, and proteolytic enzymes (CTSL, MMP2, MMP10) and determined distributions of P173, LRAP, and P190 products, the enamel proteins enamelin (ENAM) and ameloblastin (AMBN), and matrix-metalloprotease-20 (MMP20) and kallikrein-4 (KLK4). All enamel proteins and KLK4 were near-exclusive to enamel and in excellent agreement with published abundance levels. Phosphorylated P173 and LRAP products decreased in abundance from recently deposited matrix toward older enamel, mirrored by increasing abundances of testicular acid phosphatase (ACPT). Our results showed that hierarchical clustering analysis of secretory enamel links closely matching distributions of unphosphorylated P173 and LRAP products with ACPT and non-traditional amelogenesis proteins, many associated with enamel defects. We report higher protein diversity than previously published and Gene Ontology (GO)-defined protein functions related to the regulation of mineral formation in secretory enamel (e.g., casein α-S1, CSN1S1), immune response in erupted enamel (e.g., peptidoglycan recognition protein, PGRP), and phosphorylation. This study presents a novel approach to characterize and study functional relationships through spatiotemporal mapping of the ephemeral extracellular matrix proteome.

Characterization of protein extracts from different types of human teeth and insight in biomineralization

The present study describes an efficient method for isolation and purification of protein extracts from four types of human teeth i.e. molar, premolar, canine, and incisor. Detailed structural characterization of these protein extracts was done by Fourier transform infrared spectroscopy (FTIR) and circular dichroism (CD) which showed that a major fraction of the proteins present are unstructured in nature including primarily random coils in addition to the other structures like extended beta (β) structure, poly-l-proline-type II (PPII) helix, turns, with only a small fraction constituting of ordered structures like alpha (α) helix and β sheets. These resultant labile structures give the proteins the necessary flexibility that they require to interact with a variety of substrates including different ions like calcium and phosphates and for other protein-protein interactions. We also did initial studies on the mineralization of calcium phosphate with the protein extracts. Nanoparticle tracking analysis (NTA) show an increase in the size of calcium phosphate accumulation in the presence of protein extracts. We propose that protein extracts elevate the crystallization process of calcium phosphate. Our current biophysical study provides novel insights into the structural characterization of proteins from human teeth and their implications in understanding the tooth biomineralization. As per our knowledge, this is the first report which focuses on the whole protein extraction from different types of human teeth as these extracts imitate the in vivo tooth mineralization.

Cationic Intrinsically Disordered Antimicrobial Peptides (CIDAMPs) Represent a New Paradigm of Innate Defense with a Potential for Novel Anti-Infectives

In the search for potential mechanisms underlying the remarkable resistance of healthy skin against infection by soil bacteria like Pseudomonas (P.) aeruginosa we identified fragments of the intrinsically disordered protein hornerin as potent microbicidal agents in the stratum corneum. We found that, independent of the amino acid (AA)-sequence, any tested linear cationic peptide containing a high percentage of disorder-promoting AA and a low percentage of order-promoting AA is a potent microbicidal antimicrobial. We further show that the antimicrobial activity of these cationic intrinsically disordered antimicrobial peptides (CIDAMPs) depends on the peptide chain length, its net charge, lipidation and environmental conditions. The ubiquitous presence of latent CIDAMP sources in nature suggests a common and yet overlooked adapted innate disinfection system of body surfaces. The simple structure and virtually any imaginable sequence or composition of disorder-promoting AA allow the generation of a plethora of CIDAMPs. These are potential novel microbicidal anti-infectives for various bacterial pathogens, including P. aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA) and fungal pathogens like Candida albicans and Cryptococcus neoformans.

Molecular signatures of chronic periodontitis in gingiva: A genomic and proteomic analysis

BACKGROUND

To elucidate molecular signatures of chronic periodontitis (CP) using gingival tissue samples through omics-based whole-genome transcriptomic and whole protein profiling.

METHODS

Gingival tissues from 18 CP and 25 controls were analyzed using gene expression microarrays to identify gene expression patterns and the proteins isolated from these samples were subjected to comparative proteomic analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The data from transcriptomics and proteomics were integrated to reveal common shared genes and proteins.

RESULTS

The most upregulated genes in CP compared with controls were found as MZB1, BMS1P20, IGLL1/IGLL5, TNFRSF17, ALDH1A1, KIAA0125, MMP7, PRL, MGC16025, ADAM11, and the most upregulated proteins in CP compared with controls were BPI, ITGAM, CAP37, PCM1, MMP-9, MZB1, UGTT1, PLG, RAB1B, HSP90B1. Functions of the identified genes were involved cell death/survival, DNA replication, recombination/repair, gene expression, organismal development, cell-to-cell signaling/interaction, cellular development, cellular growth/proliferation, cellular assembly/organization, cellular function/maintenance, cellular movement, B-cell development, and identified proteins were involved in protein folding, response to stress, single-organism catabolic process, regulation of peptidase activity, and negative regulation of cell death. The integration and validation analysis of the transcriptomics and proteomics data revealed two common shared genes and proteins, MZB1 and ECH1.

CONCLUSION

Integrative data from transcriptomics and proteomics revealed MZB1 as a potent candidate for chronic periodontitis.

Salivary Protein Roles in Oral Health and as Predictors of Caries Risk

This work describes the current state of research on the potential relationship between protein content in human saliva and dental caries, which remains among the most common oral diseases and causes irreversible damage in the oral cavity. An understanding the whole saliva proteome in the oral cavity could serve as a prerequisite to obtaining insight into the etiology of tooth decay at early stages. To date, however, there is no comprehensive evidence showing that salivary proteins could serve as potential indicators for the early diagnosis of the risk factors causing dental caries. Therefore, proteomics indicates the promising direction of future investigations of such factors, including diagnosis and thus prevention in dental therapy.

Neanderthal and Denisova tooth protein variants in present-day humans

Environment parameters, diet and genetic factors interact to shape tooth morphostructure. In the human lineage, archaic and modern hominins show differences in dental traits, including enamel thickness, but variability also exists among living populations. Several polymorphisms, in particular in the non-collagenous extracellular matrix proteins of the tooth hard tissues, like enamelin, are involved in dental structure variation and defects and may be associated with dental disorders or susceptibility to caries. To gain insights into the relationships between tooth protein polymorphisms and dental structural morphology and defects, we searched for non-synonymous polymorphisms in tooth proteins from Neanderthal and Denisova hominins. The objective was to identify archaic-specific missense variants that may explain the dental morphostructural variability between extinct and modern humans, and to explore their putative impact on present-day dental phenotypes. Thirteen non-collagenous extracellular matrix proteins specific to hard dental tissues have been selected, searched in the publicly available sequence databases of Neanderthal and Denisova individuals and compared with modern human genome data. A total of 16 non-synonymous polymorphisms were identified in 6 proteins (ameloblastin, amelotin, cementum protein 1, dentin matrix acidic phosphoprotein 1, enamelin and matrix Gla protein). Most of them are encoded by dentin and enamel genes located on chromosome 4, previously reported to show signs of archaic introgression within Africa. Among the variants shared with modern humans, two are ancestral (common with apes) and one is the derived enamelin major variant, T648I (rs7671281), associated with a thinner enamel and specific to the Homo lineage. All the others are specific to Neanderthals and Denisova, and are found at a very low frequency in modern Africans or East and South Asians, suggesting that they may be related to particular dental traits or disease susceptibility in these populations. This modern regional distribution of archaic dental polymorphisms may reflect persistence of archaic variants in some populations and may contribute in part to the geographic dental variations described in modern humans.

Microproteome of dentoalveolar tissues

Proteomic analysis of extracellular matrices (ECM) of dentoalveolar tissues can provide insights into developmental, pathological, and reparative processes. However, targeted dissection of mineralized tissues, dental cementum (DC), alveolar bone (AB), and dentin (DE), presents technical difficulties. We demonstrate an approach combining EDTA decalcification and laser capture microdissection (LCM), followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), to analyze proteome profiles of these tissues. Using the LCM-LC-MS/MS approach, a total of 243 proteins was identified from all tissues, 193 proteins in DC, 147 in AB, and 135 proteins DE. Ninety proteins (37% of total) were common to all tissues, whereas 52 proteins (21%) were overlapping in only two. Also, 101 (42%) proteins were exclusively detected in DC (60), AB (15), or DE (26). Identification in all tissues of expected ECM proteins including collagen alpha-1(I) chain (COL1A1), collagen alpha-1(XII) chain (COL12A1), biglycan (BGN), asporin (ASPN), lumican (LUM), and fibromodulin (FMOD), served to validate the approach. Principal component analysis (PCA) and hierarchical clustering identified a high degree of similarity in DC and AB proteomes, whereas DE presented a distinct dataset. Exclusively and differentially identified proteins were detected from all three tissues. The protein-protein interaction network (interactome) of DC was notable for its inclusion of several indicators of metabolic function (e.g. mitochondrial proteins, protein synthesis, and calcium transport), possibly reflecting cementocyte activity. The DE proteome included known and novel mineralization regulators, including matrix metalloproteinase 20 (MMP-20), 5' nucleotidase (NT5E), and secreted phosphoprotein 24 (SPP-24 or SPP-2). Application of the LCM-LC-MS/MS approach to dentoalveolar tissues would be of value in many experimental designs, including developmental studies of transgenic animals, investigation of treatment effects, and identification of novel regenerative factors.

Salivary and pellicle proteome: A datamining analysis

We aimed to comprehensively compare two compartmented oral proteomes, the salivary and the dental pellicle proteome. Systematic review and datamining was used to obtain the physico-chemical, structural, functional and interactional properties of 1,515 salivary and 60 identified pellicle proteins. Salivary and pellicle proteins did not differ significantly in their aliphatic index, hydrophaty, instability index, or isoelectric point. Pellicle proteins were significantly more charged at low and high pH and were significantly smaller (10–20 kDa) than salivary proteins. Protein structure and solvent accessible molecular surface did not differ significantly. Proteins of the pellicle were more phosphorylated and glycosylated than salivary proteins. Ion binding and enzymatic activities also differed significantly. Protein-protein-ligand interaction networks relied on few key proteins. The identified differences between salivary and pellicle proteins could guide proteome compartmentalization and result in specialized functionality. Key proteins could be potential targets for diagnostic or therapeutic application.

Advances of Proteomic Sciences in Dentistry

Applications of proteomics tools revolutionized various biomedical disciplines such as genetics, molecular biology, medicine, and dentistry. The aim of this review is to highlight the major milestones in proteomics in dentistry during the last fifteen years. Human oral cavity contains hard and soft tissues and various biofluids including saliva and crevicular fluid. Proteomics has brought revolution in dentistry by helping in the early diagnosis of various diseases identified by the detection of numerous biomarkers present in the oral fluids. This paper covers the role of proteomics tools for the analysis of oral tissues. In addition, dental materials proteomics and their future directions are discussed.

Biological tooth root reconstruction with a scaffold of swine treated dentin matrix

Treated dentin matrix (TDM) is an ideal scaffolding material with odontogenic ability, which is important for supporting cell growth and regeneration of dental tissue.

Are ticks venomous animals?

INTRODUCTION

As an ecological adaptation venoms have evolved independently in several species of Metazoa. As haematophagous arthropods ticks are mainly considered as ectoparasites due to directly feeding on the skin of animal hosts. Ticks are of major importance since they serve as vectors for several diseases affecting humans and livestock animals. Ticks are rarely considered as venomous animals despite that tick saliva contains several protein families present in venomous taxa and that many Ixodida genera can induce paralysis and other types of toxicoses. Tick saliva was previously proposed as a special kind of venom since tick venom is used for blood feeding that counteracts host defense mechanisms. As a result, the present study provides evidence to reconsider the venomous properties of tick saliva.

RESULTS

Based on our extensive literature mining and in silico research, we demonstrate that ticks share several similarities with other venomous taxa. Many tick salivary protein families and their previously described functions are homologous to proteins found in scorpion, spider, snake, platypus and bee venoms. This infers that there is a structural and functional convergence between several molecular components in tick saliva and the venoms from other recognized venomous taxa. We also highlight the fact that the immune response against tick saliva and venoms (from recognized venomous taxa) are both dominated by an allergic immunity background. Furthermore, by comparing the major molecular components of human saliva, as an example of a non-venomous animal, with that of ticks we find evidence that ticks resemble more venomous than non-venomous animals. Finally, we introduce our considerations regarding the evolution of venoms in Arachnida.

CONCLUSIONS

Taking into account the composition of tick saliva, the venomous functions that ticks have while interacting with their hosts, and the distinguishable differences between human (non-venomous) and tick salivary proteins, we consider that ticks should be referred to as venomous ectoparasites.