Menzies Research Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia.
PLoS One. 2012;7(2):e31185. doi: 10.1371/journal.pone.0031185. Epub 2012 Feb 17.
Experiments with transgenic over-expressing, and null mutant mice have determined that metallothionein-I and -II (MT-I/II) are protective after brain injury. MT-I/II is primarily a zinc-binding protein and it is not known how it provides neuroprotection to the injured brain or where MT-I/II acts to have its effects. MT-I/II is often expressed in the liver under stressful conditions but to date, measurement of MT-I/II expression after brain injury has focused primarily on the injured brain itself. In the present study we measured MT-I/II expression in the liver of mice after cryolesion brain injury by quantitative reverse-transcriptase PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) with the UC1MT antibody. Displacement curves constructed using MT-I/II knockout (MT-I/II(-/-)) mouse tissues were used to validate the ELISA. Hepatic MT-I and MT-II mRNA levels were significantly increased within 24 hours of brain injury but hepatic MT-I/II protein levels were not significantly increased until 3 days post injury (DPI) and were maximal at the end of the experimental period, 7 DPI. Hepatic zinc content was measured by atomic absorption spectroscopy and was found to decrease at 1 and 3 DPI but returned to normal by 7DPI. Zinc in the livers of MT-I/II(-/-) mice did not show a return to normal at 7 DPI which suggests that after brain injury, MT-I/II is responsible for sequestering elevated levels of zinc to the liver.
MT-I/II is up-regulated in the liver after brain injury and modulates the amount of zinc that is sequestered to the liver.
实验表明，金属硫蛋白-I 和 -II（MT-I/II）在脑损伤后具有保护作用。MT-I/II 主要是一种锌结合蛋白，目前尚不清楚它如何为受损的大脑提供神经保护，或者 MT-I/II 在何处起作用以产生其效果。在应激条件下，MT-I/II 通常在肝脏中表达，但迄今为止，脑损伤后 MT-I/II 表达的测量主要集中在受损的大脑本身。在本研究中，我们通过定量逆转录聚合酶链反应（RT-PCR）和酶联免疫吸附测定（ELISA）用 UC1MT 抗体测量了冷冻损伤脑损伤后小鼠肝脏中的 MT-I/II 表达。使用 MT-I/II 敲除（MT-I/II(-/-)) 小鼠组织构建的置换曲线用于验证 ELISA。脑损伤后 24 小时内，肝 MT-I 和 MT-II mRNA 水平显著增加，但肝 MT-I/II 蛋白水平直到 3 天（DPI）后才显著增加，并在实验结束时达到最大值，7 DPI。通过原子吸收光谱法测量肝脏中的锌含量，发现 1 天和 3 天 DPI 时锌含量降低，但 7 天 DPI 时恢复正常。MT-I/II(-/-) 小鼠肝脏中的锌在 7 DPI 时未恢复正常，这表明脑损伤后，MT-I/II 负责将升高的锌水平隔离到肝脏。
脑损伤后，MT-I/II 在肝脏中上调，并调节隔离到肝脏的锌的量。
