Liu Shengnan, Liu Ying, Ma Qiwang, Cui Sheng, Liu Jiali
State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.
Arch Oral Biol. 2015 Apr;60(4):615-21. doi: 10.1016/j.archoralbio.2014.12.015. Epub 2014 Dec 31.
Taurine (2-aminoethanesulfonic acid) is the most abundant free amino acid in mammalian cells. It plays a significant role in cell development, nutrition, and survival, such as in the regulation of ion transport and osmoregulation. Cysteine sulfinate decarboxylase (CSD) is the rate-limiting biosynthetic enzyme of taurine. Recently, the synthesis of taurine has been observed in the central nervous system, kidney, liver, and muscle. However, the synthesis of taurine in the salivary glands has still not been described in detail. We have detected CSD expression in the major salivary glands of adult male mice by real-time polymerase chain reaction (RT-PCR), Western blot, and immunofluorescence. In addition, we determined the content of taurine by high-performance liquid chromatography (HPLC). The results show that taurine is present in high concentrations in the major salivary glands of male mice. CSD messenger RNA (mRNA) and protein are expressed in the major salivary glands of male mice. The relative levels of CSD mRNA increase from the submandibular gland (SMG) to the sublingual gland (SLG) and parotid gland (PG), but the levels of the CSD protein are the opposite. The immunofluorescence results indicate that CSD is mainly located in the excretory ducts (EDs) and interlobular duct (IL) of SMG and ED in SLG, respectively. These results suggest that the major salivary glands of male mice produce taurine through the CSD pathway, and the synthesis of taurine might be related to sodium reabsorption in the salivary glands.
牛磺酸（2-氨基乙磺酸）是哺乳动物细胞中含量最丰富的游离氨基酸。它在细胞发育、营养和存活中发挥着重要作用，例如在离子转运调节和渗透调节方面。半胱氨酸亚磺酸脱羧酶（CSD）是牛磺酸生物合成的限速酶。最近，在中枢神经系统、肾脏、肝脏和肌肉中均观察到了牛磺酸的合成。然而，唾液腺中牛磺酸的合成仍未得到详细描述。我们通过实时聚合酶链反应（RT-PCR）、蛋白质免疫印迹法和免疫荧光法检测了成年雄性小鼠主要唾液腺中CSD的表达。此外，我们还通过高效液相色谱法（HPLC）测定了牛磺酸的含量。结果表明，雄性小鼠主要唾液腺中牛磺酸含量很高。CSD信使核糖核酸（mRNA）和蛋白质在雄性小鼠主要唾液腺中均有表达。CSD mRNA的相对水平从下颌下腺（SMG）到舌下腺（SLG）和腮腺（PG）呈上升趋势，但CSD蛋白水平则相反。免疫荧光结果表明，CSD分别主要位于SMG的排泄管（EDs）和小叶间导管（IL）以及SLG的ED中。这些结果表明，雄性小鼠主要唾液腺通过CSD途径产生牛磺酸，且牛磺酸的合成可能与唾液腺中的钠重吸收有关。
