Wu Bin, Ueno Masaki, Kusaka Takashi, Onodera Masayuki, Huang Cheng-Long, Hosomi Naohisa, Kanenishi Kenji, Sakamoto Haruhiko
Department of Pathology and Host Defense, Faculty of Medicine, Kagawa University, Kagawa 761-0793, Japan.
Neurosci Lett. 2009 May 29;456(1):34-8. doi: 10.1016/j.neulet.2009.03.067. Epub 2009 Mar 27.
It was recently reported that some strains of senescence-accelerated mouse (SAM) including SAMR1 had a spontaneous retroviral insertional mutation in the ATP-binding cassette, sub-family B, member 1A (Abcb1a) gene, while other strains including SAMP8 had not. The Abcb1 gene product, P-glycoprotein, is a representative efflux transporter of cerebral vessels. In this study, using brain samples of SAMR1, Abcb1a gene-mutant mice, and of SAMP8 without that mutation, we examined the gene expression of some representative ATP-binding cassettes, such as Abcb1a, Abcb1b, Abcc, and Abcg2, and the protein expression of P-glycoprotein by real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting, and immunohistochemical techniques. The gene expression of Abcb1a was decreased in the brain samples of SAMR1 compared with those of SAMP8, while that of Abcb1b was increased in the samples of SAMR1 compared with those of SAMP8. There were no differences in the gene expression of Abcc and Abcg2 between the samples of SAMR1 and SAMP8. The protein expression of P-glycoprotein was decreased in the brain samples of SAMR1 compared with those of SAMP8. Immunosignals of P-glycoprotein were seen in vessels walls, mainly CD34-positive endothelial cells and partially astrocytic cells, in both mice. These findings indicate that SAMR1, Abcb1a-mutant mice, showed decreased expression of Abcb1a gene and P-glycoprotein and increased gene expression of Abcb1b, compared with those of SAMP8 without that mutation, suggesting no clear effect of increased gene expression of Abcb1b on decreased expression of P-glycoprotein. The combination of SAMR1 and SAMP8 may be a good tool to investigate which transporter, Abcb1a or Abcb1b, can be used in drug delivery into the brain.
最近有报道称，包括SAMR1在内的一些衰老加速小鼠（SAM）品系在ATP结合盒亚家族B成员1A（Abcb1a）基因中存在自发逆转录病毒插入突变，而包括SAMP8在内的其他品系则没有。Abcb1基因产物P-糖蛋白是脑血管的一种代表性外排转运蛋白。在本研究中，我们使用SAMR1、Abcb1a基因突变小鼠以及无该突变的SAMP8小鼠的脑样本，通过实时定量逆转录聚合酶链反应（RT-PCR）、蛋白质印迹法和免疫组织化学技术，检测了一些代表性ATP结合盒的基因表达，如Abcb1a、Abcb1b、Abcc和Abcg2，以及P-糖蛋白的蛋白质表达。与SAMP8相比，SAMR1脑样本中Abcb1a的基因表达降低，而与SAMP8相比，SAMR1样本中Abcb1b的基因表达增加。SAMR1和SAMP8样本之间Abcc和Abcg2的基因表达没有差异。与SAMP8相比，SAMR1脑样本中P-糖蛋白的蛋白质表达降低。在两种小鼠的血管壁中均可见P-糖蛋白的免疫信号，主要在CD34阳性内皮细胞和部分星形细胞中。这些发现表明，与无该突变的SAMP8相比，Abcb1a基因突变小鼠SAMR1表现出Abcb1a基因和P-糖蛋白表达降低，Abcb1b基因表达增加，提示Abcb1b基因表达增加对P-糖蛋白表达降低没有明显影响。SAMR1和SAMP8的组合可能是研究哪种转运蛋白（Abcb1a或Abcb1b）可用于药物脑内递送的良好工具。
