Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawai'i , 651 Ilalo Street, Honolulu, HI 96813, USA.
Antioxid Redox Signal. 2010 Apr 1;12(7):809-18. doi: 10.1089/ars.2009.2883.
Selenoproteins contain the trace element selenium incorporated as selenocysteine, the 21st amino acid. Some members of the selenoprotein family, such as the glutathione peroxidases, have well-characterized antioxidant activity, functioning in enzymatic breakdown of hydroperoxides to protect cells against oxidative stress. However, the functions of many of the 25 human selenoproteins, including the brain-enriched selenoprotein M, are unknown. We investigated selenoprotein M function by manipulating expression in murine hippocampal HT22 cells, cerebellar astrocyte C8-D1A cells, and primary neuronal cultures. Overexpression of the protein resulted in a reduction in reactive oxygen species and apoptotic cell death in response to oxidative challenge with hydrogen peroxide. In contrast, knock-down of selenoprotein M using shRNA in primary neuronal cultures caused apoptotic cell death comparable to levels resulting from addition of hydrogen peroxide. Calcium measurements with the indicator cameleon demonstrated that overexpression of selenoprotein M decreased calcium influx in response to hydrogen peroxide. Additionally, knock-down of selenoprotein M expression in cortical cultures caused higher baseline levels of cytosolic calcium than in control cells. These results suggest that selenoprotein M may have an important role in protecting against oxidative damage in the brain and may potentially function in calcium regulation.
硒蛋白包含痕量元素硒，以硒代半胱氨酸的形式存在，这是第 21 种氨基酸。硒蛋白家族的一些成员，如谷胱甘肽过氧化物酶，具有明确的抗氧化活性，在酶促分解过氧化物方面发挥作用，以保护细胞免受氧化应激。然而，许多 25 个人类硒蛋白的功能，包括富含脑的硒蛋白 M，仍然未知。我们通过在鼠海马 HT22 细胞、小脑星形胶质细胞 C8-D1A 细胞和原代神经元培养物中操纵表达来研究硒蛋白 M 的功能。该蛋白的过表达导致活性氧和细胞凋亡减少，对过氧化氢的氧化应激有反应。相比之下，使用 shRNA 在原代神经元培养物中敲低硒蛋白 M 会导致细胞凋亡，与添加过氧化氢的水平相当。用指示剂 cameleon 进行的钙测量表明，过表达硒蛋白 M 可减少对过氧化氢的钙内流。此外，皮质培养物中硒蛋白 M 表达的敲低导致细胞浆内钙的基础水平高于对照细胞。这些结果表明，硒蛋白 M 可能在保护大脑免受氧化损伤方面发挥重要作用，并可能在钙调节中发挥作用。
