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Peroxisomes Are Highly Abundant and Heterogeneous in Human Parotid Glands. Int J Mol Sci 2023; 24:ijms24054783. [PMID: 36902220 PMCID: PMC10003153 DOI: 10.3390/ijms24054783] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/18/2023] [Accepted: 02/20/2023] [Indexed: 03/06/2023] Open
Abstract
The parotid gland is one of the major salivary glands producing a serous secretion, and it plays an essential role in the digestive and immune systems. Knowledge of peroxisomes in the human parotid gland is minimal; furthermore, the peroxisomal compartment and its enzyme composition in the different cell types of the human parotid gland have never been subjected to a detailed investigation. Therefore, we performed a comprehensive analysis of peroxisomes in the human parotid gland's striated duct and acinar cells. We combined biochemical techniques with various light and electron microscopy techniques to determine the localization of parotid secretory proteins and different peroxisomal marker proteins in parotid gland tissue. Moreover, we analyzed the mRNA of numerous gene encoding proteins localized in peroxisomes using real-time quantitative PCR. The results confirm the presence of peroxisomes in all striated duct and acinar cells of the human parotid gland. Immunofluorescence analyses for various peroxisomal proteins showed a higher abundance and more intense staining in striated duct cells compared to acinar cells. Moreover, human parotid glands comprise high quantities of catalase and other antioxidative enzymes in discrete subcellular regions, suggesting their role in protection against oxidative stress. This study provides the first thorough description of parotid peroxisomes in different parotid cell types of healthy human tissue.
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Nandula SR, Huxford I, Wheeler TT, Aparicio C, Gorr SU. The parotid secretory protein BPIFA2 is a salivary surfactant that affects lipopolysaccharide action. Exp Physiol 2020; 105:1280-1292. [PMID: 32390232 DOI: 10.1113/ep088567] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 05/06/2020] [Indexed: 12/30/2022]
Abstract
NEW FINDINGS What is the central question of this study? The salivary protein BPIFA2 binds lipopolysaccharide, but its physiological function is not known. This study uses a new knockout mouse model to explore the physiological role of BPIFA2 in the oral cavity and systemic physiology. What is the main finding and its importance? BPIFA2 is a crucial surfactant in mouse saliva. In its absence, saliva exhibits the surface tension of water. Depletion of BPIFA2 affects salivary and ingested lipopolysaccharide and leads to systemic sequelae that include increased insulin secretion and metabolomic changes. These results suggest that the lipopolysaccharide-binding activity of BPIFA2 affects the activity of ingested lipopolysaccharide in the intestine and that BPIFA2 depletion causes mild metabolic endotoxaemia. ABSTRACT Saliva plays important roles in the mastication, swallowing and digestion of food, speech and lubrication of the oral mucosa, antimicrobial and anti-inflammatory activities, and the control of body temperature in grooming animals. The salivary protein BPIFA [BPI fold containing family A member 2; former names: parotid secretory protein (PSP), SPLUN2 and C20orf70] is related to lipid-binding and lipopolysaccharide (LPS)-binding proteins expressed in the mucosa. Indeed, BPIFA2 binds LPS, but the physiological role of BPIFA2 remains to be determined. To address this question, Bpifa2 knockout (Bpifa2tm1(KOMP)Vlcg ) (KO) mice were phenotyped, with emphasis on the saliva and salivary glands. Stimulated whole saliva collected from KO mice was less able to spread on a hydrophobic surface than wild-type saliva, and the surface tension of KO saliva was close to that of water. These data suggest that BPIFA2 is a salivary surfactant that is mainly responsible for the low surface tension of mouse saliva. The reduced surfactant activity of KO saliva did not affect consumption of dry food or grooming, but saliva from KO mice contained less LPS than wild-type saliva. Indeed, mice lacking BPIFA2 responded to ingested LPS with an increased stool frequency, suggesting that BPIFA2 plays a role in the solubilization and activity of ingested LPS. Consistent with these findings, BPIFA2-depleted mice also showed increased insulin secretion and metabolomic changes that were consistent with a mild endotoxaemia. These results support the distal physiological function of a salivary protein and reinforce the connection between oral biology and systemic disease.
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Affiliation(s)
- Seshagiri Rao Nandula
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN, USA.,Department of Biochemistry & Molecular Biology, George Washington University, Washington, DC, USA
| | - Ian Huxford
- Department of Restorative Sciences, University of Minnesota School of Dentistry, Minneapolis, MN, USA
| | | | - Conrado Aparicio
- Department of Restorative Sciences, University of Minnesota School of Dentistry, Minneapolis, MN, USA
| | - Sven-Ulrik Gorr
- Department of Diagnostic and Biological Sciences, University of Minnesota School of Dentistry, Minneapolis, MN, USA
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Metzler MA, Venkatesh SG, Lakshmanan J, Carenbauer AL, Perez SM, Andres SA, Appana S, Brock GN, Wittliff JL, Darling DS. A systems biology approach identifies a regulatory network in parotid acinar cell terminal differentiation. PLoS One 2015; 10:e0125153. [PMID: 25928148 PMCID: PMC4416001 DOI: 10.1371/journal.pone.0125153] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/16/2015] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVE The transcription factor networks that drive parotid salivary gland progenitor cells to terminally differentiate, remain largely unknown and are vital to understanding the regeneration process. METHODOLOGY A systems biology approach was taken to measure mRNA and microRNA expression in vivo across acinar cell terminal differentiation in the rat parotid salivary gland. Laser capture microdissection (LCM) was used to specifically isolate acinar cell RNA at times spanning the month-long period of parotid differentiation. RESULTS Clustering of microarray measurements suggests that expression occurs in four stages. mRNA expression patterns suggest a novel role for Pparg which is transiently increased during mid postnatal differentiation in concert with several target gene mRNAs. 79 microRNAs are significantly differentially expressed across time. Profiles of statistically significant changes of mRNA expression, combined with reciprocal correlations of microRNAs and their target mRNAs, suggest a putative network involving Klf4, a differentiation inhibiting transcription factor, which decreases as several targeting microRNAs increase late in differentiation. The network suggests a molecular switch (involving Prdm1, Sox11, Pax5, miR-200a, and miR-30a) progressively decreases repression of Xbp1 gene transcription, in concert with decreased translational repression by miR-214. The transcription factor Xbp1 mRNA is initially low, increases progressively, and may be maintained by a positive feedback loop with Atf6. Transfection studies show that Xbp1 activates the Mist1 promoter [corrected]. In addition, Xbp1 and Mist1 each activate the parotid secretory protein (Psp) gene, which encodes an abundant salivary protein, and is a marker of terminal differentiation. CONCLUSION This study identifies novel expression patterns of Pparg, Klf4, and Sox11 during parotid acinar cell differentiation, as well as numerous differentially expressed microRNAs. Network analysis identifies a novel stemness arm, a genetic switch involving transcription factors and microRNAs, and transition to an Xbp1 driven differentiation network. This proposed network suggests key regulatory interactions in parotid gland terminal differentiation.
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Affiliation(s)
- Melissa A. Metzler
- Department of Oral Immunology and Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America
- Department of Biochemistry & Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
- Institute for Molecular Diversity and Drug Design, University of Louisville, Louisville, Kentucky, United States of America and
- * E-mail:
| | - Srirangapatnam G. Venkatesh
- Department of Oral Immunology and Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America
- Institute for Molecular Diversity and Drug Design, University of Louisville, Louisville, Kentucky, United States of America and
| | - Jaganathan Lakshmanan
- Department of Oral Immunology and Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America
| | - Anne L. Carenbauer
- Department of Oral Immunology and Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America
| | - Sara M. Perez
- Department of Oral Immunology and Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America
| | - Sarah A. Andres
- Department of Biochemistry & Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
- Institute for Molecular Diversity and Drug Design, University of Louisville, Louisville, Kentucky, United States of America and
| | - Savitri Appana
- Department of Bioinformatics and Biostatistics, University of Louisville, Louisville, Kentucky, United States of America
| | - Guy N. Brock
- Department of Bioinformatics and Biostatistics, University of Louisville, Louisville, Kentucky, United States of America
| | - James L. Wittliff
- Department of Biochemistry & Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
- Institute for Molecular Diversity and Drug Design, University of Louisville, Louisville, Kentucky, United States of America and
| | - Douglas S. Darling
- Department of Oral Immunology and Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America
- Department of Biochemistry & Molecular Biology, University of Louisville, Louisville, Kentucky, United States of America
- Institute for Molecular Diversity and Drug Design, University of Louisville, Louisville, Kentucky, United States of America and
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Yuan YW, Tamamura R, Lei L, Katase N, Ara Sathi G, Ito S, Tsujigiwa H, Nagatsuka H. The Ability of Transplanted Bone Marrow-Derived Cells to Differentiate into Parenchymal Cells of Salivary Glands. J HARD TISSUE BIOL 2013. [DOI: 10.2485/jhtb.22.433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Multiple roles for the actin cytoskeleton during regulated exocytosis. Cell Mol Life Sci 2012; 70:2099-121. [PMID: 22986507 DOI: 10.1007/s00018-012-1156-5] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/28/2012] [Accepted: 08/30/2012] [Indexed: 01/01/2023]
Abstract
Regulated exocytosis is the main mechanism utilized by specialized secretory cells to deliver molecules to the cell surface by virtue of membranous containers (i.e., secretory vesicles). The process involves a series of highly coordinated and sequential steps, which include the biogenesis of the vesicles, their delivery to the cell periphery, their fusion with the plasma membrane, and the release of their content into the extracellular space. Each of these steps is regulated by the actin cytoskeleton. In this review, we summarize the current knowledge regarding the involvement of actin and its associated molecules during each of the exocytic steps in vertebrates, and suggest that the overall role of the actin cytoskeleton during regulated exocytosis is linked to the architecture and the physiology of the secretory cells under examination. Specifically, in neurons, neuroendocrine, endocrine, and hematopoietic cells, which contain small secretory vesicles that undergo rapid exocytosis (on the order of milliseconds), the actin cytoskeleton plays a role in pre-fusion events, where it acts primarily as a functional barrier and facilitates docking. In exocrine and other secretory cells, which contain large secretory vesicles that undergo slow exocytosis (seconds to minutes), the actin cytoskeleton plays a role in post-fusion events, where it regulates the dynamics of the fusion pore, facilitates the integration of the vesicles into the plasma membrane, provides structural support, and promotes the expulsion of large cargo molecules.
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