Chrono-Proteomics of Human Saliva: Variations of the Salivary Proteome during Human Development

Abstract

An important contribution to the variability of any proteome is given by the time dimension that should be carefully considered to define physiological modifications. To this purpose, whole saliva proteome was investigated in a wide age range. Whole saliva was collected from 17 preterm newborns with a postconceptional age at birth of 178-217 days. In these subjects sample collection was performed serially starting immediately after birth and within about 1 year follow-up, gathering a total of 111 specimens. Furthermore, whole saliva was collected from 182 subjects aged between 0 and 17 years and from 23 adults aged between 27 and 57 years. The naturally occurring intact salivary proteome of the 316 samples was analyzed by low- and high-resolution HPLC-ESI-MS platforms. Proteins peculiar of the adults appeared in saliva with different time courses during human development. Acidic proline-rich proteins encoded by PRH2 locus and glycosylated basic proline-rich proteins encoded by PRB3 locus appeared following 180 days of postconceptional age, followed at 7 months (±2 weeks) by histatin 1, statherin, and P-B peptide. The other histatins and acidic proline-rich proteins encoded by PRH1 locus appeared in whole saliva of babies from 1 to 3 weeks after the normal term of delivery, S-type cystatins appeared at 1 year (±3 months), and basic proline-rich proteins appeared at 4 years (±1 year) of age. All of the proteinases involved in the maturation of salivary proteins were more active in preterm than in at-term newborns, on the basis of the truncated forms detected. The activity of the Fam20C kinase, involved in the phosphorylation of various proteins, started around 180 days of postconceptional age, slowly increased reaching values comparable to adults at about 2 years (±6 months) of age. Instead, MAPK14 involved in the phosphorylation of S100A9 was fully active since birth also in preterm newborns.

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

“…Aim of the present study was the characterization of the acidinsoluble fraction of whole saliva from preterm human newborns by 2-DE and high-resolution tandem mass spectrometry, thus extending the results of previous studies [8,9]. This approach allowed the identification of several proteins, the majority, but not all, not detected in the acid-soluble fraction.…”

“…Acidic treatment causes precipitation of several salivary proteins. In previous studies, our group was engaged in the proteomic characterization of the acidic soluble components of human saliva collected from donors of various ages [6,8,9,11].…”

“…Among them, cytoskeletal keratin 13, belonging to type I (67, 69, 94), and keratin 4 type II (66, 74, 75, 78), annexin A1 (31, 32) and annexin A2 (36, 83), actin cytoplasmic 1 (88), serpin B3 (33) and serpin B5 (89), glyceraldehyde-3-phosphate dehydrogenase (37), alpha enolase (35), serum albumin (92) and cornulin (72, 73) were identified. Among the proteins localized in the lower part of the gel, we identified S100A8 (8,9) and S100A9 (1, 2 and 11), cystatin B (6), thioredoxin (12), epidermal fatty acid-binding protein (E-FABP) in 3, galectin-7 (81), and calmodulin-like protein 3 (14).…”

“…N 40 protein masses often undetectable in adult saliva have been evidenced and their PTMs have been characterized [8]. A very recent paper has analysed, by means of HPLC-low-and high-resolution ESI-MS platforms, the time dimension variability of the salivary proteome in a very high number of samples from preterm newborns with a PCA at birth varying from 178 to 217 days, children between 0 and 17 years and adults [9]. The paper evidenced that proteins peculiar of adults appeared in saliva with different time courses during human development, for example histatin 1, statherin and P-B peptide appeared at 7 months of PCA while basic proline-rich proteins appeared roughly at 4 years of age.…”

Multi-omics profiling reveals that eating difficulties developed consecutively to artificial nutrition in the neonatal period are associated to specific saliva composition

“…One should note however that the purpose of this study was not to explore age variations, elsewhere described by other authors [21], and therefore we tested the age effect only on discriminant variables. The fact that cystatin SN abundance in particular is not significantly affected by age of the subjects contrasts with findings of another study [21] but may be explained by the lower number of subjects here.…”