Apoptosis in Early Salivary Gland Duct Morphogenesis and Lumen Formation

• Published in: Journal of dental research Vol. 95; no. 3; pp. 277 - 283
• Main Authors: Teshima, T.H.N., Wells, K.L., Lourenço, S.V., Tucker, A.S.
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01.03.2016; SAGE PUBLICATIONS, INC
• Subjects: Amino Acid Chloromethyl Ketones - pharmacology; Animals; Apoptosis; Apoptosis - physiology; Caspase; Caspase 3 - analysis; Caspase 3 - drug effects; Caspase Inhibitors - pharmacology; Caspase-3; Cavitation; Cell death; Cell Polarity - physiology; Cytokeratin; Embryonic Development - physiology; Embryos; Epithelium - embryology; Immunofluorescence; In Situ Nick-End Labeling; Keratin-7 - analysis; Mice; Morphogenesis; Morphogenesis - physiology; Mucosa; Oral cavity; Organ Culture Techniques; Polarity; Proteins; Saliva; Salivary Ducts - drug effects; Salivary Ducts - embryology; Salivary gland; Submandibular Gland - embryology; United States > US; keratins; cell death; caspases; embryonic development; developmental biology; salivary ducts
• ISSN: 0022-0345; 1544-0591
• DOI: 10.1177/0022034515619581

Salivary glands are essential for the maintenance of oral health by providing lubrication and antimicrobial protection to the mucosal and tooth surfaces. Saliva is modified and delivered to the oral cavity by a complex multifunctional ductal system. During development, these ducts form as solid tubes, which undergo cavitation to create lumens. Apoptosis has been suggested to play a role in this cavitation process along with changes in cell polarity. Here, we show that apoptosis occurs from the very earliest stages of mouse salivary gland development, much earlier than previously reported. Apoptotic cells were observed in the center of the first epithelial stalk at early-stage embryonic day 12.5 (E12.5) according to both TUNEL staining and cleaved caspase 3 immunofluorescence. The presumptive lumen space was highlighted by the colocalization of a predictive lumen marker, cytokeratin 7. At E14.5, as lumens start to form throughout the glands, apoptotic expression decreased while cytokeratin 7 remained positive. In vitro inhibition of all caspases in E12.5 and E13.5 salivary glands resulted in wider ducts, as compared with the controls, and a defect in lumen formation. In contrast, no such defect in lumen formation was observed at E14.5. Our data indicate that apoptosis is involved during early stages of gland formation (E12.5 onward) and appears important for shaping the forming ducts.