Salivary gland ionocyte organization and function during homeostasis, repair, and disease

唾液腺是产生唾液的外分泌腺。充足的供应 唾液对口腔组织的维持至关重要。唾液由多种电解质组成 还含有免疫球蛋白、蛋白质、酶和粘蛋白，这表明唾液具有 复杂的函数。唾液腺导管的一个重要功能是调节离子。 内稳态[1]。上皮细胞离子稳态功能障碍可导致多人 疾病[2，3]。我们使用他莫昔芬诱导型FGF10CreERT2：R26的血统追踪实验- 番茄小鼠在纹状体中发现了表达Fgf10的新的上皮细胞群 颌下腺(SMG)、腮腺(PG)的颗粒(GCT)和排泄管(ED) 腺体。重要的是，Fgf10的血统追踪显示，直到出生后第7天(P7) 间充质Fgf10表达细胞存在，但在P10、Fgf10表达后， 间质关闭，而导管上皮细胞亚群开始表达Fgf10。vbl.使用 荧光激活细胞分选(FACS)分离间充质细胞和上皮细胞 对Fgf10细胞进行RNA测序(RNA-seq)。对这种RNA的分析- 结合P1和成人单细胞RNA-Seq(ScRNAseq)数据的序列分析 SMGs显示上皮性Fgf10种群与标记的已知导管种群重叠 按Ascl3。此外，这些上皮性Fgf10细胞表达了许多基因特征 古型离子细胞：BSND，Foxi1，Foxi2，Asgr1，Stap1，H- ATPase(V-ATPase)和SLC12A1/2和SLC9a4转运蛋白的标志物。最重要的是 FGF10细胞表达囊性纤维化跨膜电导调节因子(CFTR) 在外分泌中起关键作用，包括在唾液腺中。我们认为这些上皮细胞 Fgf10/Ascl3/CFTR细胞是一种特化的导管唾液腺离子细胞。此外，使用两个 干燥综合征模型：NOD.B10SnH_2B/J和血栓反应蛋白-1缺失(TSP1-/-) 小鼠，我们发现Fgf10的表达和离子细胞的数量显著减少。 疾病的发展。我们还发现，从SMG分离的上皮Fgf10细胞是 能够维持祖细胞和肌上皮细胞的增殖和生长，提示 离子细胞在导管维持中的额外作用。在此应用程序中，我们将确定角色 Fgf10信号在SMG再生和离子细胞功能中的作用，定义控制因素 并确定慢性炎症如何影响离子细胞的功能。在……里面 此外，与霍夫曼博士的团队合作，使用批量RNA-seq和scRNA-seq数据，我们 将调查唾液腺是否有一种或几种类型的离子细胞。我们的 所提出的研究将为离子细胞在基础生物学中的未来研究提供一个起点平台 和临床研究。

The salivary glands are exocrine glands that produce saliva. An adequate supply of saliva is critical to the maintenance of oral tissue. Saliva is composed of a variety of electrolytes and also contains immunoglobulins, proteins, enzymes and mucins, suggesting that saliva has a complex function. An important function of salivary gland ducts is to regulate ion homeostasis[1]. Dysfunction of epithelial ion homeostasis can lead to several human diseases[2, 3]. Our lineage tracing experiments using a tamoxifen inducible FGF10CreERT2:R26- Tomato mouse identified new epithelial populations of the Fgf10 expressing cells in the striated (SD), granular (GCT) and excretory ducts (ED) of submandibular (SMG) and parotid (PG) glands. Importantly Fgf10 lineage tracing shows that until postnatal day 7 (P7) only mesenchymal Fgf10 expressing cells are present, however after P10, Fgf10 expression in the mesenchyme shuts down, while a subset of ductal epithelial cells starts to express Fgf10. Using Fluorescence Activated Cell Sorting (FACS) we isolated both mesenchymal and epithelial populations of Fgf10+ cells and performed RNA sequencing (RNA-seq). Analysis of this RNA- seq data combined with analysis of single cell RNA-Seq (scRNAseq) data from P1 and adult SMGs showed that epithelial Fgf10+ populations overlap with the known duct population marked by Ascl3. Moreover, these epithelial Fgf10+ cells expressed many gene characteristics for an ancient type of ionocyte cell: Bsnd, Foxi1, Foxi2, Asgr1, Stap1, several subunits of the H+- ATPase (V-ATPase) and markers of SLC12A1/2 and Slc9a4 transporters. Most importantly Fgf10+ cells expressed cystic fibrosis transmembrane conductance regulator (Cftr) that plays a key role in exocrine secretion, including in salivary glands. We propose that these epithelial Fgf10+/Ascl3+/Cftr+ cells are specialized duct salivary gland ionocytes. Moreover, using two models of Sjogrens syndrome: the NOD.B10Sn-H2b/J and the thrombospondin-1 null (TSP1-/-) mice, we showed a significant decrease in Fgf10+ expression and the number of ionocytes with disease progression. We also showed that epithelial Fgf10+ cells isolated from the SMG are able to maintain proliferation and growth of progenitor and myoepithelial cells, suggesting an additional role for ionocytes in ductal maintenance. In this application we will determine the role of Fgf10 signaling in SMG regeneration and ionocyte function, define factors that control ionocyte differentiation and determine how chronic inflammation affects ionocyte function. In addition, in collaboration with Dr. Hoffman's group using bulk RNA-seq and scRNA-seq data we will investigate whether salivary glands have one type or several types of ionocytes. Our proposed study will provide a starting platform for future studies of ionocytes in basic biology and clinical research.