Sox9 regulates the luminal stem/progenitor cell properties of salivary glands

Exocrine glands share a common morphology consisting of ductal, acinar, and basal/myoepithelial cells, but their functions and mechanisms of homeostasis differ among tissues. Salivary glands are an example of exocrine glands, and they have been reported to contain multipotent stem cells that differentiate into other tissues. In this study, we purified the salivary gland stem/progenitor cells of adult mouse salivary glands using the cell surface marker CD133 by flow cytometry. CD133⁺ cells possessed stem cell capacity, and the transplantation of CD133⁺ cells into the submandibular gland reconstituted gland structures, including functional acinar. CD133⁺ cells were sparsely distributed in the intercalated and exocrine ducts and expressed Sox9 at higher levels than CD133^- cells. Moreover, we demonstrated that Sox9 was required for the stem cell properties CD133⁺ cells, including colony and sphere formation. Thus, the Sox9-related signaling may control the regeneration salivary glands.