Regulation of Salivary Proteins

Johnson, D. A.; Alvares, Olav; Etzel, Kenneth R.; Kalu, Dike N.

doi:10.1177/00220345870660023201

Cited by 30 publications

(31 citation statements)

References 60 publications

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“…x 61,000. position or structure of one or more of the acinar proteins, which occurs as a result of the diabetic condition, is responsible for the enhanced endocytic activity by the duct cells. Alterations of parotid salivary protein composition have been reported in experimental diabetes (Anderson and Johnson, 1981) and in other conditions (Johnson et al, 1987), but whether specific chemical modifications occur in individual proteins is not known. Thus, in certain pathological conditions in which "abnormal" or modified proteins may be secreted by the acinar cells, the duct cells may function to remove these proteins from the saliva before it reaches the oral cavity.…”

Section: Discussionmentioning

confidence: 99%

Endocytosis of Proteins by Salivary Gland Duct Cells

et al. 1987

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The ability of the intralobular duct cells of the rat parotid gland to take up protein from the lumen was examined by retrograde infusion of exogenous proteins and by immunogold localization of endogenous secretory proteins. Small amounts of native horseradish peroxidase (HRP) were taken up by intercalated and striated duct cells, and were present in small vesicles, multivesicular bodies, and lysosomes. In contrast, HRP modified by periodate oxidation was avidly internalized by the duct cells and was present in large apical vacuoles that acquired lysosomal hydrolase activity. Native and cationized ferritin were taken up in a similar manner when infused at a high concentration (up to 10 mg/mL). At lower concentrations (0.3-1.0 mg/mL), endocytosis of cationized ferritin occurred mainly in small apical tubules and vesicles in striated duct cells. Little native ferritin was taken up at these concentrations. After stimulation of acinar cell secretion by isoproterenol, similar vacuoles were occasionally observed in both intercalated and striated duct cells. Labeling of thin sections with antibodies to amylase and to a 26,000-dalton secretory protein (protein B1), followed by protein A-gold, revealed the presence of these proteins in the vacuoles, indicating endocytosis of acinar secretory proteins by the duct cells. Although uptake of acinar proteins by duct cells occurs at a low rate in normal animals, previous work suggests that extensive endocytosis may occur in certain pathological conditions. This may be a mechanism for removing abnormal or modified proteins from saliva before it reaches the oral cavity.

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Section: Discussionmentioning

confidence: 99%

Endocytosis of Proteins by Salivary Gland Duct Cells

et al. 1987

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“…While the composition varies between individuals, salivary composition remains relatively stable under most physiologic conditions (Oberg et al, 1982). However, changes in salivary gene expression are seen in hormone-treated or chronically stimulated animals (Johnson et al, 1987), and the induction of proline-rich proteins by isoproterenol or tannin is well-documented (Robinovitch et al, 1977;Tu et al, 1993). Several salivary proteins play roles in host defense, including PSP, histatins, cystatins, peroxidase, and defensins.…”

Section: (A) Parotid Secretory Granulesmentioning

confidence: 99%

Parotid Secretory Granules: Crossroads of Secretory Pathways and Protein Storage

2005

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Saliva plays an important role in digestion, host defense, and lubrication. The parotid gland contributes a variety of secretory proteins-including amylase, proline-rich proteins, and parotid secretory protein (PSP)-to these functions. The regulated secretion of salivary proteins ensures the availability of the correct mix of salivary proteins when needed. In addition, the major salivary glands are targets for gene therapy protocols aimed at targeting therapeutic proteins either to the oral cavity or to circulation. To be successful, such protocols must be based on a solid understanding of protein trafficking in salivary gland cells. In this paper, model systems available to study the secretion of salivary proteins are reviewed. Parotid secretory proteins are stored in large dense-core secretory granules that undergo stimulated secretion in response to extracellular stimulation. Secretory proteins that are not stored in large secretory granules are secreted by either the minor regulated secretory pathway, constitutive secretory pathways (apical or basolateral), or the constitutive-like secretory pathway. It is proposed that the maturing secretory granules act as a distribution center for secretory proteins in salivary acinar cells. Protein distribution or sorting is thought to involve their selective retention during secretory granule maturation. Unlike regulated secretory proteins in other cell types, salivary proteins do not exhibit calcium-induced aggregation. Instead, sulfated proteoglycans play a role in the storage of secretory proteins in parotid acinar cells. This work suggests that unique sorting and retention mechanisms are responsible for the distribution of secretory proteins to different secretory pathways from the maturing secretory granules in parotid acinar cells.

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“…The procedures for collection and analysis of parotid saliva have been described in an earlier paper (Johnson et al, 1987a). Briefly, saliva was collected from cannulated parotid ducts into tared vials for 30 minutes following intraperitoneal injections of pilocarpine (5 mg/animal) and isoproterenol (5 mg/animal).…”

Section: Methodsmentioning

confidence: 99%

“…Many of the proteins of rat parotid saliva have since been identified, and the electrophoretic mobility of the individual proteins in a sodium dodecyl sulfate polyacrylamide gel system has been determined (Keller et aL, 1975;Iversen et al, 1982;Johnson, 1983Johnson, , 1984. Based on this information, we observed in a recent study that the proportion of total protein in rat parotid saliva contributed by the acidic and basic proline-rich proteins was increased by 64% in hyperthyroid rats, while that of a cysteine-rich protein identified as Fraction V was reduced by 26% (Johnson et al, 1987a).…”

Section: Introductionmentioning

confidence: 93%

Influence of Thyroxine in the Regulation of Rat Parotid Salivary Protein Composition

Johnson

Kalu

1988

J Dent Res

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This study tested the role of thyroxine in the regulation of the protein composition of rat parotid saliva. Thyro-parathyroidectomy was performed on two groups of rats, one of which subsequently received thyroxine replacement; the third group was sham-operated. Parotid saliva was collected on the eighth day after surgery, with pilocarpine and isoproterenol used as a secretory stimulus. The volume of saliva collected in 30 min from the thyro-parathyroidectomized rats was 55% less than that collected from sham-operated rats. In the thyro-parathyroidectomized rats, the protein concentration as measured by absorption at 215 nm was unaltered, but that measured by the Lowry procedure was 43% higher. Spectrophotometric scans of Coomassie Blue-stained gels following sodium dodecylsulfate polyacrylamide gel electrophoresis of the secreted proteins showed an 18% reduction in the proportion of protein attributable to amylase and a 43% reduction in proportion of acidic and basic proline-rich proteins following thyro-parathyroidectomy; deoxyribonuclease and two other major secretory proteins (Fraction I and Fraction V) were increased (38%, 20%, and 46%, respectively). These changes in flow rate, protein concentration by the Lowry assay, and protein composition were prevented by treatment of thyro-parathyroidectomized rats with thyroxine replacement and are in opposition to those changes we reported earlier for hyperthyroid rats. The results indicate that the flow of saliva as well as the synthesis of the various salivary proteins are influenced by thyroxine.

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Regulation of Salivary Proteins

Cited by 30 publications

References 60 publications

Endocytosis of Proteins by Salivary Gland Duct Cells

Endocytosis of Proteins by Salivary Gland Duct Cells

Parotid Secretory Granules: Crossroads of Secretory Pathways and Protein Storage

Influence of Thyroxine in the Regulation of Rat Parotid Salivary Protein Composition

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