Teshima T H N, Wells K L, Lourenço S V, Tucker A S
Department of Stomatology, School of Dentistry, University of Sao Paulo, São Paulo, Brazil.
Department of Craniofacial Development and Stem Cell Biology, King's College London, London, UK.
J Dent Res. 2016 Mar;95(3):277-83. doi: 10.1177/0022034515619581. Epub 2015 Dec 1.
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.
唾液腺通过为黏膜和牙齿表面提供润滑和抗菌保护，对维持口腔健康至关重要。唾液通过一个复杂的多功能导管系统进行修饰并输送至口腔。在发育过程中，这些导管最初形成实心管，随后经历空化过程以形成管腔。有人提出凋亡以及细胞极性的变化在这个空化过程中发挥作用。在此，我们表明凋亡在小鼠唾液腺发育的最早阶段就已发生，比先前报道的要早得多。根据TUNEL染色和裂解的半胱天冬酶3免疫荧光检测，在胚胎第12.5天（E12.5）早期的第一个上皮茎中心观察到凋亡细胞。预测的管腔标记细胞角蛋白7的共定位突出了推测的管腔空间。在E14.5时，随着整个腺体开始形成管腔，凋亡表达下降，而细胞角蛋白7仍为阳性。与对照组相比，在E12.5和E13.5唾液腺中对所有半胱天冬酶进行体外抑制导致导管更宽，并且管腔形成存在缺陷。相比之下，在E14.5时未观察到这种管腔形成缺陷。我们的数据表明凋亡在腺体形成的早期阶段（从E12.5开始）就有涉及，并且对于塑造正在形成的导管似乎很重要。
