Department of Developmental Neurobiology, NYS Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA.
School of Veterinary Medicine, Konkuk University, Seoul, South Korea.
Adv Exp Med Biol. 2017;975 Pt 1:461-474. doi: 10.1007/978-94-024-1079-2_37.
Taurine, a sulfur containing amino acid, has various physiological functions including development of the eye and brain, immune function, reproduction, osmo-regulatory function as well as anti-oxidant and anti-inflammatory activities. In order to understand the physiological role, we developed taurine deficient mice deleting a rate-liming enzyme, cysteine sulfinic acid decarboxylase (CSAD) for biosynthesis of taurine. Taurine was measured in various tissues including the liver, brain, lung, spleen, thymus, pancreas, heart, muscle and kidney as well as plasma from CSAD knock-out mice (CSAD KO) with and without treatment of taurine in the drinking water at the age of 2 months (2 M). Taurine was determined using HPLC as a phenylisothiocyanate derivative of taurine at 254 nm. Taurine concentrations in the liver and kidney from homozygotes of CSAD KO (HO), in which CSAD level is high, were 90% and 70% lower than WT, respectively. Taurine concentrations in the brain, spleen and lung, where CSAD level is low, were 21%, 20% and 28% lower than WT, respectively. At 2 M, 1% taurine treatment of HO restored taurine concentrations in all tissues compared to that of WT. To select an appropriate taurine treatment, HO were treated with various concentrations (0.05, 0.2, 1%) of taurine for 4 months (4 M). Restoration of taurine in all tissues except the liver, kidney and lung requires 0.05% taurine to be restored to that of WT. The liver and kidney restore taurine back to WT with 0.2% taurine. To examine which enzymes influence taurine concentrations in various tissues from WT and HO at 2 M, expression of five taurine-related enzymes, two antioxidant enzymes as well as lactoferrin (Lft) and prolactin receptor (Prlr) was determined using RT qPCR. The expression of taurine transporter in the liver, brain, muscle and kidney from HO was increased except in the lung. Our data showed expression of glutamate decarboxylase-like 1(Gadl-1) was increased in the brain and muscle in HO, compared to WT, indicating taurine in the brain and muscle from HO was replenished through taurine transporter and increased biosynthesis of taurine by up-regulated Gadl-1. The expression of glutathione peroxidase 3 was increased in the brain and peroxireductase 2 was increased in the liver and lung, suggesting taurine has anti-oxidant activity. In contrast to newborn and 1 month CSAD KO, Ltf and Prlr in the liver from CSAD KO at 2 M were increased more than two times and 52%, respectively, indicating these two proteins may be required for pregnancy of CSAD KO. Ltf in HOT1.0 was restored to WT, while Prlr in HOT1.0 was increased more than HO, explaining improvement of neonatal survival with taurine supplementation.These data are essential for investigating the role of taurine in development of the brain and eye, immune function, reproduction and glucose tolerance.
牛磺酸是一种含硫氨基酸，具有多种生理功能，包括眼睛和大脑的发育、免疫功能、生殖、渗透调节功能以及抗氧化和抗炎活性。为了了解其生理作用，我们构建了缺乏限速酶半胱氨酸亚磺酸脱羧酶（CSAD）的牛磺酸生物合成缺陷型小鼠。在 2 月龄（2M）时，用高效液相色谱法（HPLC）检测 CSAD 敲除小鼠（CSAD KO）及其在饮用水中添加和不添加牛磺酸时的各种组织（包括肝、脑、肺、脾、胸腺、胰腺、心脏、肌肉和肾）以及血浆中的牛磺酸。用 HPLC 作为牛磺酸的苯异硫氰酸酯衍生物在 254nm 处测定牛磺酸。CSAD KO（HO）杂合子（CSAD 水平高）的肝和肾中的牛磺酸浓度分别比 WT 低 90%和 70%。CSAD 水平低的脑、脾和肺中的牛磺酸浓度分别比 WT 低 21%、20%和 28%。在 2M 时，1%的牛磺酸处理使 HO 中的所有组织中的牛磺酸浓度恢复到 WT 水平。为了选择合适的牛磺酸处理方法，HO 用不同浓度（0.05、0.2、1%）的牛磺酸处理了 4 个月（4M）。除了肝、肾和肺外，所有组织中的牛磺酸恢复都需要 0.05%的牛磺酸才能恢复到 WT 水平。肝和肾用 0.2%的牛磺酸即可将牛磺酸恢复到 WT 水平。为了研究 2M 时 WT 和 HO 中各种组织中牛磺酸浓度的变化，我们使用 RT-qPCR 检测了 5 种牛磺酸相关酶、2 种抗氧化酶以及乳铁蛋白（Lft）和催乳素受体（Prlr）的表达。HO 中肝、脑、肌肉和肾中的牛磺酸转运蛋白表达增加，除了肺。我们的数据显示，HO 脑中谷氨酸脱羧酶样 1（Gadl-1）的表达增加，而肌肉中的表达增加，与 WT 相比，表明 HO 中的脑和肌肉中的牛磺酸通过牛磺酸转运蛋白补充，并通过上调 Gadl-1 增加牛磺酸的生物合成。HO 中脑和肌肉中的谷胱甘肽过氧化物酶 3（GPx3）表达增加，肝和肺中的过氧化物还原酶 2（PRDX2）表达增加，表明牛磺酸具有抗氧化活性。与新生和 1 月龄的 CSAD KO 不同，2M 时 CSAD KO 肝中的 Lft 和 Prlr 分别增加了两倍以上和 52%，表明这两种蛋白质可能是 CSAD KO 妊娠所必需的。HOT1.0 中的 Ltf 恢复到 WT 水平，而 HOT1.0 中的 Prlr 增加超过 HO，这解释了牛磺酸补充对新生儿存活率的改善。这些数据对于研究牛磺酸在大脑和眼睛发育、免疫功能、生殖和葡萄糖耐量中的作用至关重要。
