Dataset Information

Salivary gland homeostasis is maintained through acinar cell self-duplication.

ABSTRACT: Current dogma suggests that salivary gland homeostasis is stem cell dependent. However, the extent of stem cell contribution to salivary gland maintenance has not been determined. We investigated acinar cell replacement during homeostasis, growth, and regeneration, using an inducible CreER(T2) expressed under the control of the Mist1 gene locus. Genetic labeling, followed by a chase period, showed that acinar cell replacement is not driven by the differentiation of unlabeled stem cells. Analysis using R26(Brainbow2.1) reporter revealed continued proliferation and clonal expansion of terminally differentiated acinar cells in all major salivary glands. Induced injury also demonstrated the regenerative potential of pre-labeled acinar cells. Our results support a revised model for salivary gland homeostasis based predominantly on self-duplication of acinar cells, rather than on differentiation of stem cells. The proliferative capacity of differentiated acinar cells may prove critical in the implementation of cell-based strategies to restore the salivary glands.

SUBMITTER: Aure MH

PROVIDER: S-EPMC4406828 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Salivary gland homeostasis is maintained through acinar cell self-duplication.

Aure Marit H MH Konieczny Stephen F SF Ovitt Catherine E CE

Developmental cell 20150402 2

Current dogma suggests that salivary gland homeostasis is stem cell dependent. However, the extent of stem cell contribution to salivary gland maintenance has not been determined. We investigated acinar cell replacement during homeostasis, growth, and regeneration, using an inducible CreER(T2) expressed under the control of the Mist1 gene locus. Genetic labeling, followed by a chase period, showed that acinar cell replacement is not driven by the differentiation of unlabeled stem cells. Analysis ...[more]

PMID: 25843887

Similar Datasets

Project description:The vitamin D receptor (VDR) and its ligand 1,25(OH)2D3 (1,25D) impact differentiation and exert anti-tumor effects in many tissues, but its role in salivary gland has yet to be defined. Using immunohistochemistry (IHC), we have detected strong VDR expression in murine and human salivary gland ducts. Compared to normal gland, VDR protein expression was retained in differentiated human pleomorphic adenoma (PA) but was undetectable in undifferentiated PA and in carcinomas, suggesting deregulation of VDR during salivary cancer progression. To gain insight into the potential role of VDR in salivary cancer, we assessed the effects of vitamin D in vivo and in vitro. Despite the presence of VDR in salivary gland, chronic dietary vitamin D restriction did not alter morphology of the salivary epithelium in C57/Bl6 mice. The localization of VDR in ductal epithelium prompted us to examine the effects of 1,25D in an established cell line (mSGc) derived from normal murine submandibular gland (SMG). This previously characterized cell line consists of multiple stem, progenitor and differentiated cell types as determined by mutually exclusive cellular expression of basal, ductal and myoepithelial markers. We demonstrated VDR expression and regulation of VDR target genes Vdr and Postn by 1,25D in mSGc, indicating functional ligand-mediated transcriptional activity. The effect of VDR signaling on epithelial differentiation markers was assessed by qPCR and IHC in mSGc cells treated with 1,25D. We found that 1,25D reduced mRNA expression of the basal cell progenitor marker keratin 5 (K5) and increased expression of the differentiated ductal cell marker keratin 7 (K7). Further, we found that 1,25D significantly decreased the number of proliferating cells, including proliferating K5+ cells. Characterization of cell cycle by Muse cytometry indicated 1,25D treatment decreased cells in S, G2, and M phase. The inhibition of K5+ cell proliferation by 1,25D is of particular interest because K5+ basal cells contribute to a wide variety of salivary tumor types. Our studies suggest that 1,25D alters cancer-relevant progenitor and differentiation markers in the salivary gland.

Project description:The loss of salivary gland function caused by radiation therapy of the head and neck or autoimmune disease such as Sjögren's syndrome is a serious condition that affects a patient's quality of life. Due to the combined exocrine and endocrine functions of the salivary gland, gene transfer to the salivary glands holds the potential for developing therapies for disorders of the salivary gland and the expression of therapeutic proteins via the exocrine pathway to the mouth, upper gastrointestinal tract, or endocrine pathway, systemically, into the blood. Recent clinical success with viral vector-mediated gene transfer for the treatment of irradiation-induced damage to the salivary glands has highlighted the need for the development of novel vectors with acinar cell tropism able to result in stable long-term transduction. Previous studies with adeno-associated virus (AAV) focused on the submandibular gland and reported mostly ductal cell transduction. In this study, we have screened AAV vectors for acinar cell tropism in the parotid gland utilizing membrane-tomato floxed membrane-GFP transgenic mice to screen CRE recombinase encoding AAV vectors of different clades to rapidly identify capsid isolates able to transduce salivary gland acinar cells. We determined that AAVRh10 and a novel isolate found as a contaminant of a laboratory stock of simian adenovirus SV15, AAV44.9, are both able to transduce parotid and sublingual acinar cells. Persistence and localization of transduction of these AAVs were tested using vectors encoding firefly luciferase, which was detected 6 months after vector administration. Most luciferase expression was localized to the salivary gland compared to that of distal organs. Transduction resulted in robust secretion of recombinant protein in both blood and saliva. Transduction was species specific, with AAVRh10 having stronger transduction activity in rats compared with AAV44.9 or AAV2 but weaker in human primary salivary gland cells. This work demonstrates efficient transduction of parotid acinar cells by AAV that resulted in secretion of recombinant protein in both serum and saliva.

Project description:Radiation therapy for head and neck cancers leads to permanent xerostomia due to the loss of secretory acinar cells in the salivary glands. Regenerative treatments utilizing primary submandibular gland (SMG) cells show modest improvements in salivary secretory function, but there is limited evidence of salivary gland regeneration. We have recently shown that poly(ethylene glycol) (PEG) hydrogels can support the survival and proliferation of SMG cells as multicellular spheres in vitro. To further develop this approach for cell-based salivary gland regeneration, we have investigated how different modes of PEG hydrogel degradation affect the proliferation, cell-specific gene expression, and epithelial morphology within encapsulated salivary gland spheres. Comparison of non-degradable, hydrolytically-degradable, matrix metalloproteinase (MMP)-degradable, and mixed mode-degradable hydrogels showed that hydrogel degradation by any mechanism is required for significant proliferation of encapsulated cells. The expression of acinar phenotypic markers Aqp5 and Nkcc1 was increased in hydrogels that are MMP-degradable compared with other hydrogel compositions. However, expression of secretory acinar proteins Mist1 and Pip was not maintained to the same extent as phenotypic markers, suggesting changes in cell function upon encapsulation. Nevertheless, MMP- and mixed mode-degradability promoted organization of polarized cell types forming tight junctions and expression of the basement membrane proteins laminin and collagen IV within encapsulated SMG spheres. This work demonstrates that cellularly remodeled hydrogels can promote proliferation and gland-like organization by encapsulated salivary gland cells as well as maintenance of acinar cell characteristics required for regenerative approaches. Investigation is required to identify approaches to further enhance acinar secretory properties.Statement of significanceRegenerative strategies to replace damaged salivary glands require the function and organization of acinar cells. Hydrogel-based approaches have shown promise to control cell function and phenotype. However, little is known about how specific parameters, such as the mechanism of hydrogel degradation (e.g., hydrolytic or enzymatic), influence the viability, proliferation, organization, and phenotype of salivary gland cells. In this work, it is shown that hydrogel-encapsulated primary salivary gland cell proliferation is dependent upon hydrogel degradation. Hydrogels crosslinked with enzymatically degradable peptides promoted the expression of critical acinar cell markers, which are typically downregulated in primary cultures. Furthermore, salivary gland cells encapsulated in enzymatically- but not hydrolytically-degradable hydrogels displayed highly organized and polarized salivary gland cell markers, which mimics characteristics found in native gland tissue. In sum, results indicate that salivary gland cells respond to cellularly remodeled hydrogels, resulting in self-assembly and organization akin to acini substructures of the salivary gland.

Dataset Information

Salivary gland homeostasis is maintained through acinar cell self-duplication.

Publications

Salivary gland homeostasis is maintained through acinar cell self-duplication.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets