The minor salivary gland cell type enriched transcriptome

The minor salivary glands are numerous small glands dispersed throughout the oral cavity and upper aerodigestive tract. There are approximately 800-1000 of these minor salivary glands, each typically 1-2 mm in diameter, located in the submucosa of the oral mucosa, including the buccal, labial, and lingual areas, as well as the soft and hard palate. Unlike the much larger major salivary glands (parotid, submandibular and sublingual), they are not encapsulated by connective tissue. While the minor salivary glands primarily produce mucous secretions, which play important roles in lubricating the oral cavity and aiding in various functions such as swallowing and speech, they also contribute to a smaller degree to the serous salivary secretions, which contain some digestive enzymes.

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2258 genes were predicted to have cell type specificity in the minor salivary gland.

  • 14 cell types profiled
  • 458 very highly enriched genes
  • 539 highly enriched genes
  • 1261 moderately enriched genes

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Minor salivary gland cell type enriched transcriptome: Summary

Genes with predicted cell type specificity within minor salivary gland are detailed in Table 1. Identified genes are subdivided into 3 specificity categories, based on the difference between the enrichment score in the corresponding cell type, compared to the other cell types profiled in the tissue (see Methods Summary page for details):

  • Predicted specificity: ´Very high´ - Differential score vs. other profiled cell types within the tissue >0.35
  • Predicted specificity: ´High´ - Differential score vs. other profiled cell types within the tissue >0.25
  • Predicted specificity: ´Moderate´ - Differential score vs. other profiled cell types within the tissue >0.15


Table 1. Number of genes in each specificity category in the minor salivary gland cell types.

Cell type Very highHighModerate Total enriched
Minor salivary glandular cells 206 222 353 781
Minor salivary gland ductal cells 16 31 63 110
Minor salivary gland basal cells 0 22 171 193
Mitotic cells (Minor salivary gland) 0 42 94 136
Adipocytes (Minor salivary gland) 16 15 10 41
Endothelial cells 19 59 175 253
Smooth muscle cells 11 5 8 24
Fibroblasts 0 26 114 140
Macrophages 6 33 170 209
Neutrophils 1 5 5 11
Mast cells 0 7 6 13
T-cells 7 29 55 91
Plasma cells 176 43 37 256
All cell types 4585391261 2258


Figure 1. Bar plot of the number of enriched genes in the cell types of the minor salivary gland, divided by specificity category

Minor salivary gland cell type enriched transcriptome: Illustrative examples

Salivary glandular cells

Salivary glandular cells produce mucin-rich secretions that help lubricate the oral cavity, protect the oral mucosa, and aid in swallowing and speech. They can also secrete proteins with antimicrobial properties, such as lysozyme and lactoferrin, contributing to the protective functions of saliva in the oral cavity. Genes enriched in the salivary glandular cells include Aquaporin 5 (AQP5), a water channel protein, Lactoperoxidase (LPO), a protein with antimicrobial properties, Zymogen Granule Protein 16B (ZG16B), a protein predicted to enable carbohydrate binding activity and WD repeat domain, phosphoinositide interacting 1 (WIPI1), a protein that can regulate the assembly of multiprotein complexes.


AQP5 - Minor salivary gland

AQP5

LPO - Minor salivary gland

LPO

ZG16B - Minor salivary gland

ZG16B

WIPI1 - Minor salivary gland

WIPI1

Salivary gland ductal cells

Salivary duct cells play a crucial role in modifying the composition of saliva as it passes through the ductal system. These cells actively reabsorb sodium and secrete potassium, helping to regulate the final electrolyte content of saliva before it enters the oral cavity. Genes classified as having specificity in the cells of the salivary ducts include the enzymes ATPase H+ transporting V1 subunit B1 (ATP6V1B1), Hydroxysteroid 11-Beta Dehydrogenase 2 (HSD11B2) and Oxoglutarate Dehydrogenase L (OGDHL), and the protease inhibitor WAP Four-Disulfide Core Domain 2 (WFDC2).


ATP6V1B1 - Minor salivary gland

ATP6V1B1

HSD11B2 - Minor salivary gland

HSD11B2

OGDHL - Minor salivary gland

OGDHL

WFDC2 - Minor salivary gland

WFDC2

Salivary gland basal cells

Basal cells in the minor salivary glands are stem-like cells located at the base of the glandular epithelium. They serve as progenitor cells, capable of differentiating into other cell types to maintain and repair the gland's tissue. Basal cells are crucial for the regeneration and maintenance of the salivary glands and ductal cells. Enriched genes within the basal cells include Keratin 5 (KRT5), S100 calcium-binding protein A2 (S100A2), which is involved in cell cycle regulation, and Laminin Subunit Beta 3 (LAMB3), a component of the basement membrane.


KRT5 - Minor salivary gland

KRT5

S100A2 - Minor salivary gland

S100A2

LAMB3 - Minor salivary gland

LAMB3