Mao Xianrong, Yang Shao-Hua, Simpkins James W, Barger Steven W
Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.
J Neurochem. 2007 Mar;100(5):1300-14. doi: 10.1111/j.1471-4159.2006.04297.x.
Sp-family transcription factors (Sp1, Sp3 and Sp4) contain a zinc-finger domain that binds to DNA sequences rich in G-C/T. As assayed by RT-PCR analysis of mRNA, western-blot analysis, immunofluorescence, and antibody-dependent "supershift" of DNA-binding assays, the prominent Sp-family factors in cerebral neurons were identified as Sp3 and Sp4. By contrast, glial cells were found to express Sp1 and Sp3. We previously showed that the pattern of G-C/T binding activity of Sp-family factors is rapidly and specifically altered by the calcium influx accompanying activation of glutamate receptors. Here, we demonstrate that Sp-factor activity is also lost after a cerebral ischemia/reperfusion injury in vivo. Consistent with its calcium-dependent nature, we found that glutamate's effect on Sp-family factors could be blocked by inhibitors of calpains, neutral cysteine proteases activated by calcium. Purified calpain I cleaved Sp3 and Sp4 into products that retained G-C/T-binding activity, consistent with species observed in glutamate-treated neurons. These data provide details of an impact of glutamate-receptor activation on molecular events connected to gene expression.
Sp 家族转录因子（Sp1、Sp3 和 Sp4）含有一个锌指结构域，可与富含 G-C/T 的 DNA 序列结合。通过对 mRNA 的 RT-PCR 分析、蛋白质免疫印迹分析、免疫荧光以及 DNA 结合试验中的抗体依赖性“超迁移”检测，确定大脑神经元中主要的 Sp 家族因子为 Sp3 和 Sp4。相比之下，发现神经胶质细胞表达 Sp1 和 Sp3。我们之前表明，伴随谷氨酸受体激活的钙内流会迅速且特异性地改变 Sp 家族因子的 G-C/T 结合活性模式。在此，我们证明在体内脑缺血/再灌注损伤后 Sp 因子活性也会丧失。与其钙依赖性性质一致，我们发现谷氨酸对 Sp 家族因子的作用可被钙蛋白酶（由钙激活的中性半胱氨酸蛋白酶）抑制剂阻断。纯化的钙蛋白酶 I 将 Sp3 和 Sp4 切割成保留 G-C/T 结合活性的产物，这与在谷氨酸处理的神经元中观察到种类一致。这些数据详细说明了谷氨酸受体激活对与基因表达相关分子事件的影响。
