Department of Physiology, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271-8587, Japan; Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271-8587, Japan.
Laboratory of Veterinary Biochemistry, Nihon University College of Bioresource Sciences, Fujisawa, Kanagawa 252-0880, Japan.
Arch Oral Biol. 2017 Sep;81:141-150. doi: 10.1016/j.archoralbio.2017.05.007. Epub 2017 May 15.
Salivary acinar and duct cells show different expression patterns of claudins, which may reflect their different functions. To study the role of claudins in saliva secretion, we examined alterations in the expression patterns of cell adhesion molecules in parotid glands of γ-irradiated rats and analyzed the influence of those changes on intercellular barrier function using primary cultures of parotid acinar cells.
Rats were γ-irradiated with doses of 5, 15 or 20Gy, and expression levels of cell adhesion molecules were examined by immunoblotting analysis. Acinar cells were isolated from parotid glands and were cultured in the absence or presence of the Src kinase inhibitor PP1. Changes in protein and mRNA expression patterns were determined by immunoblotting and by RT-PCR analyses, respectively. Intercellular barrier function was examined by measuring transepithelial electrical resistance and the paracellular flux of FITC-dextran.
In irradiated parotid glands, the expression of claudin-4 was enhanced at 15Gy or higher, levels that induce the hyposecretion of saliva, although that increase was transient. At 30days after irradiation, expression levels of cell adhesion molecules were decreased. In primary cultures, the expression of claudin-4 was also increased transiently but the expression of claudin-3 and E-cadherin was decreased. The barrier function of tight junctions was disrupted although the localization of occludin was maintained. The Src kinase inhibitor PP1 suppressed those changes in gene expression and retained the intercellular barrier function.
These results suggest that the inhibition of Src signaling maintains the barrier functions of intercellular junctions in salivary glands, which can be lost due to tissue injury.
唾液腺泡和导管细胞显示不同的紧密连接蛋白表达模式，这可能反映了它们不同的功能。为了研究紧密连接蛋白在唾液分泌中的作用，我们研究了 γ 射线照射大鼠腮腺中细胞黏附分子表达模式的改变，并分析了这些变化对腮腺腺泡细胞原代培养中细胞间屏障功能的影响。
大鼠接受 5、15 或 20Gy 的 γ 射线照射，通过免疫印迹分析检测细胞黏附分子的表达水平。从腮腺中分离出腺泡细胞，并在无 Src 激酶抑制剂 PP1 或存在 PP1 的情况下进行培养。通过免疫印迹和 RT-PCR 分析分别测定蛋白和 mRNA 表达模式的变化。通过测量跨上皮电阻和 FITC-葡聚糖的旁流来检测细胞间屏障功能。
在照射的腮腺中，claudin-4 的表达在 15Gy 或更高时增强，这会导致唾液分泌减少，尽管这种增加是短暂的。照射后 30 天，细胞黏附分子的表达水平降低。在原代培养中，claudin-4 的表达也短暂增加，但 claudin-3 和 E-钙黏蛋白的表达减少。尽管紧密连接蛋白 occludin 的定位保持不变，但紧密连接的屏障功能被破坏。Src 激酶抑制剂 PP1 抑制了这些基因表达的变化，并保留了细胞间的屏障功能。
这些结果表明，抑制 Src 信号通路可维持唾液腺细胞间连接的屏障功能，而这种功能可能因组织损伤而丧失。
