Postnatal expression of sialin in the mouse submandibular gland

Are salivary NO2- / NO2- and NO3- levels biomarkers for dental caries in children? Systematic review and meta-analysis

The literature is conflicting regarding salivary nitrite (NO2-)/nitrite and nitrate (NO2- and NO3-) levels in children affected by dental caries. For this reason, a systematic review to provide a consensus on the subject was propose, whose objective is to verify whether these molecules could be used as biomarkers in children with caries. A comprehensive search was performed on online database and eleven articles were included in the meta-analysis. The methodological quality of studies was assessed by Newcastle-Ottawa Scale recommended for case-control studies and by AXIS tool for cross-sectional studies. Grading of Recommendations Assessment, Development and Evaluation was used for the assessment of the certainty of the evidence for each outcome. The results showed lower NO2- levels in the group of children affected by dental caries (SMD = -2.18 [-3.24, -1.13], p < 0.01). Age, saliva collection and methods of evaluation can impact the results. When evaluating the severity of the condition, an important variation was detected in relation to the different evaluation methods NO2-/NO2- and NO3-. In conclusion, based on the evidence presented, the results suggest that NO2- levels in saliva are a possible biomarker of dental caries. Results should be evaluated with caution due to the very low evidence from primary studies. Longitudinal studies are necessary to strengthen this hypothesis.

Altered sialin mRNA gene expression in type 2 diabetic male Wistar rats: implications for nitric oxide deficiency

Nitrate therapy has been suggested to boost nitric oxide (NO) levels in type 2 diabetes (T2D); however, little is known about nitrate transport across the membranes. This study aimed to assess changes in the mRNA expression of sialin, as a nitrate transporter, in the main tissues of rats with T2D. Rats were divided into two groups (n = 6/group): Control and T2D. A high-fat diet combined with a low dose of streptozotocin (STZ, 30 mg/kg) was used to induce T2D. At month 6, samples from the main tissues of rats were used to measure the mRNA expression of sialin and levels of NO metabolites. Rats with T2D had lower nitrate levels in the soleus muscle (66%), lung (48%), kidney (43%), aorta (30%), adrenal gland (58%), epididymal adipose tissue (eAT) (61%), and heart (37%) and had lower nitrite levels in the pancreas (47%), kidney (42%), aorta (33%), liver (28%), eAT (34%), and heart (32%). The order of sialin gene expression in control rats was: soleus muscle > kidney > pancreas > lung > liver > adrenal gland > brain > eAT > intestine > stomach > aorta > heart. Compared to controls, rats with T2D had higher sialin mRNA expressions in the stomach (2.1), eAT (2.0), adrenal gland (1.7), liver (8.9), and soleus muscle (3.4), and lower sialin expression in the intestine (0.56), pancreas (0.42), and kidney (0.44), all P values < 0.05. These findings indicate altered sialin mRNA expression in the main tissues of male T2D rats and may have implications for future NO-based treatment of T2D.

Transcriptome analysis reveals sex-specific alterations in gonads of green mussel exposed to organophosphorus insecticide triazophos

Triazophos (TP) is a widespread pollutant in aquatic environments. A sex-specific metabolic response in green-lipped mussel Perna viridis to TP exposure was observed in our previous study, and this led us to investigate the mechanisms associated with its toxicity. P. viridis were subjected to chronic exposure (15 days) to TP at 35 μg/L to compare the sex-biased transcriptomic profiles in the gonads of male and female mussels. We identified 632 differentially expressed genes (DEGs) (348 up-regulated and 284 down-regulated) in TP-exposed males, and only 61 DEGs (9 up-regulated and 52 down-regulated) in TP-exposed females. Many DEGs were found to be involved in the nervous, reproductive endocrine, oxidative stress, and immune systems of P. viridis. Additionally, enzymatic activity analysis indicated TP induced neurotoxic effects and oxidative damage to the mussels. Our results demonstrate that the stress response and molecular mechanisms of TP toxicology are different between female and male mussels.

Sialin mediates submandibular gland regeneration ability by affecting polysialic acid synthesis

OBJECTIVES

Sialin is a multifunctional molecule with a well-described role in physiological equilibrium regulation. The aim of this study was to elucidate the role of sialin in salivary glands regeneration.

MATERIALS AND METHODS

Submandibular gland duct ligation/deligation of rat was performed to develop a rat model of submandibular gland regeneration. Phenotype changes were investigated using western blotting and quantitative real-time polymerase chain reaction, as well as immunohistochemical staining. LV-slc17a5-RNAi vectors were injected into the submandibular glands via retroductal instillation to establish a stable sialin knockdown model.

RESULTS

Submandibular gland tissue structure could completely restore 28 days after duct deligation, when the duct had been ligated for 7 days. The expression of sialin, polysialic acid, and polysialyltransferase IV was significantly increased on day 0 after duct deligation, and it returned to the level of the control group at day 28. Moreover, sialin knockdown could weakened gland regeneration by reducing polysialic acid synthesis. Supplementing drinking water with polysialic acid precursors (ManNAc) in drinking water could partially rescue submandibular gland regeneration in sialin knockdown rats.

CONCLUSION

These data indicated that sialin was vital for submandibular gland regeneration which mediated the process of gland regeneration by affecting the polysialic acid synthesis.

Transcriptome analysis reveals potential immune function-related regulatory genes/pathways of female Lubo goat submandibular glands at different developmental stages

Background

The submandibular glands, as major salivary glands, participate in rumen digestion in goats. Sialic acid, lysozyme, immunoglobulin A (IgA), lactoferrin and other biologically active substances secreted in the submandibular glands were reported in succession, which suggests that the submandibular gland may have immune functions in addition to participating in digestion. The aim of this study was to map the expression profile of differentially expressed genes (DEGs) at three different stages by transcriptome sequencing, screen immune-related genes and pathways by bioinformatics methods, and predict the immune function of submandibular glands at different developmental stages.

Methods

Nine submandibular gland tissue samples were collected from groups of 1-month-old kids, 12-month-old adolescent goats and 24-month-old adult goats (3 samples from each group), and high-throughput transcriptome sequencing was conducted on these samples. The DEGs among the three stages were screened and analysed. Key genes and signalling pathways were selected via protein-protein interaction (PPI) network analysis.

Results

The results revealed 2,706, 2,525 and 52 DEGs between 1-month-old and 12-month-old goats, between 1-month-old and 24-month-old goats, and between 12-month-old and 24-month-old goats, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that most of the DEGs were enriched in immune- related GO terms and pathways. Based on functional enrichment analysis and network analysis, 10 genes (PTPRC, CD28, SELL, LCP2, MYC, LCK, ZAP70, ITGB2, SYK and CCR7), two signalling pathways (the T cell receptor signalling pathway and the NF-κβ signalling pathway) and eight GO terms (T cell receptor signalling pathway, neutrophil mediated immunity, B cell mediated immunity, regulation of alpha-beta T cell activation, positive regulation of T cell proliferation, regulation of leukocyte differentiation, positive regulation of antigen receptor-mediated signalling pathway, positive regulation of lymphocyte proliferation) that may play key roles in the immune functions of the goat submandibular glands at different developmental stages were identified. Moreover, we found that eight antibacterial peptide-encoding genes were downregulated in the tuberculosis and salivary secretion pathways, while all immunoglobulins were upregulated in 10 immune system pathways. These findings indicate that the submandibular glands may be important immunological organs during the growth process of goats and that the immune function of these glands gradually weakens with age up to 12 months but remains relatively stable after 12 months of age. Overall, this study will improve our understanding of transcriptional regulation related to goat submandibular gland immune function.

Sialin (SLC17A5) functions as a nitrate transporter in the plasma membrane

In vivo recycling of nitrate (NO(3)(-)) and nitrite (NO(2)(-)) is an important alternative pathway for the generation of nitric oxide (NO) and maintenance of systemic nitrate-nitrite-NO balance. More than 25% of the circulating NO(3)(-) is actively removed and secreted by salivary glands. Oral commensal bacteria convert salivary NO(3)(-) to NO(2)(-), which enters circulation and leads to NO generation. The transporters for NO(3)(-) in salivary glands have not yet been identified. Here we report that sialin (SLC17A5), mutations in which cause Salla disease and infantile sialic acid storage disorder (ISSD), functions as an electrogenic 2NO(3)(-)/H(+) cotransporter in the plasma membrane of salivary gland acinar cells. We have identified an extracellular pH-dependent anion current that is carried by NO(3)(-) or sialic acid (SA), but not by Br(-), and is accompanied by intracellular acidification. Both responses were reduced by knockdown of sialin expression and increased by the plasma membrane-targeted sialin mutant (L22A-L23A). Fibroblasts from patients with ISSD displayed reduced SA- and NO(3)(-)-induced currents compared with healthy controls. Furthermore, expression of disease-associated sialin mutants in fibroblasts and salivary gland cells suppressed the H(+)-dependent NO(3)(-) conductance. Importantly, adenovirus-dependent expression of the sialinH183R mutant in vivo in pig salivary glands decreased NO(3)(-) secretion in saliva after intake of a NO(3)(-)-rich diet. Taken together, these data demonstrate that sialin mediates nitrate influx into salivary gland and other cell types. We suggest that the 2NO(3)(-)/H(+) transport function of sialin in salivary glands can contribute significantly to clearance of serum nitrate, as well as nitrate recycling and physiological nitrite-NO homeostasis.