Sialin调控涎腺再生的作用和机制

Sialin, a transporter of sialic acid and nitrate, possesses the vital role on the development of epithelium and nerve. Sialin in the epithelium could mediate the location of peripheral autonomic nerve by controlling the growth of glial cells around the epithelium. During the regeneration of salivary glands, the peripheral autonomic nerve could maintain and mediate the growth, differentiation, and maturation of salivary epithelium, and the denervation of salivary glands causes it lose the ability of regeneration. The role and mechanism of Sialin in salivary epithelium on the salivary gland regeneration still are not uncovered. To reveal the role and mechanism of Sialin on the regeneration of salivary glands, the relationship of salivary epithelium and autonomic innervations is focused. The defeated Sialin in salivary cells and tissues is produced by knockdown and mutant gene transfection in vitro, and mutant gene transduction in vivo. Ligation and deligation of submandibular gland main ducts causes a model of salivary gland regeneration. Radiation causes a model of salivary gland damage. To evaluated the conditions that defeated Sialin leads the changes of sialic acid transporting and metabolism, the regeneration of salivary glands, and autonomic innervations, histological stain, qPCR, confocal, Western Blot, high performance liquid chromatography, etc. are utilized. Furthermore, a preclinical study is done in which the precursor of sialic acid is administrated pre-radiation to prevent salivary glands from damage caused by radiation.

Sialin为唾液酸及硝酸盐转运蛋白，在上皮和神经系统发育中起到重要的作用。上皮组织中的Sialin可以调节上皮组织周围神经胶质细胞的生长，从而调控外周植物神经纤维的分布。涎腺再生过程中，植物神经可以调控上皮的生长、分化和成熟，失神经支配涎腺无法再生。涎腺上皮组织中的Sialin在涎腺再生中作用和机制还不清楚。通过基因静默、突变基因转染、下颌下腺导管转导Sialin突变基因制造Sialin功能缺陷涎腺上皮细胞和组织，以小鼠涎腺再生模型和涎腺放射损伤模型为研究对象。通过组织学、qPCR、confocal、Western Blot、高效液相色谱等技术，检测涎腺上皮Sialin功能缺陷对涎腺上皮唾液酸转运和代谢、涎腺上皮再生以及神经支配的影响，从而揭示涎腺上皮Sialin在涎腺再生的作用和机制。进一步通过补充唾液酸前体预防小鼠涎腺放射损伤。

唾液酸转运蛋白Sialin可以将溶酶体内唾液酸(Sialic acid, SA)转运到胞浆。SA形成的多聚唾液酸(polysialic acid, PSA)与细胞膜上的神经粘附因子(neural cell adhesion molecule, NCAM)结合形成的PSA-NCAM复合体在神经及肝等组织的再生中发挥了重要作用。在唾液腺器官发育和再生过程中副交感神经的支配起到了重要作用。研究发现Sialin在小鼠唾液腺发育过程中呈现特异性的高表达，然而其是否参与唾液腺再生及其机制仍不清楚。本研究旨在通过建立唾液腺再生模型探讨Sialin及PSA-NCAM在唾液腺再生中的作用及其在失神经支配的唾液腺损伤中的作用。本课题组通过结扎下颌下腺导管及副交感神经成功建立了下颌下腺再生模型及失神经支配的下颌下腺损伤模型，通过下颌下腺注射慢病毒成功建立了沉默下颌下腺Sialin表达的小鼠模型。利用免疫组织化学染色、RT-PCR、western blot等方法进行检测。结果表明：Sialin通过PSA-NCAM复合体在唾液腺再生中发挥了重要作用，Sialin沉默后下颌下腺再生能力明显降低，通过补充SA前体可以部分恢复下颌下腺再生能力。在失神经支配的唾液腺损伤中，PSA-NCAM复合体同样发挥了重要作用。该研究可以为临床修复唾液腺损伤提供新的思路。