Memory and learning disorder analysis using mutation mouse for mental retadation related gene ATRX and elucidation of the genetic control abnormality.

ATRX综合征的致病基因定位于X染色体上，表现为智力低下和α地中海贫血等表型。据报道，当外显子2发生突变时，智力就会降低。然后，我们与Dr.En Li和Dr.H.Beppu （Harvard University， USA）合作，对C57BL6小鼠系统进行回交，从129小鼠系统到六代（N6），以产生用于行为分析的ATRX突变小鼠。使用C75BL6， N6代小鼠，在2003 - 2004年为期两年的研究期间，获得了以下结果：(1)突变小鼠在突变位点敲入了高水平的Lac Z基因。X-gal染色在海马、大脑皮层和小脑中均可见到Lac Z基因。(2)用识别ATRX c -末端的抗体进行免疫染色。结果，与野生型相比，ATRX蛋白在大脑皮层、小脑和海马中的低表达在ATRX突变小鼠中被识别出更多的mpus。(3)使用识别ATRX c -末端的抗体，Western blot结果显示突变小鼠脑组织蛋白表达比野生型减少约50%。众所周知，海马体控制着记忆和学习。因此，为了分析其功能，我们采用Morris水迷宫实验检测了空间记忆学习，发现突变小鼠的记忆和学习能力不如野生型小鼠。这一发现在消除恐水症环境下的饮食报酬试验中得到了证实。我们还进行了野外试验和家笼活动试验，以检查突变小鼠的其他行为障碍。从这些测试中，我们注意到突变小鼠的多动症。虽然在野生型小鼠中受到明亮光线的影响，但在突变小鼠中，在明暗环境中的逗留时间是相反的。行为学分析显示，ATRX突变小鼠表现为学习能力低下、畏光敏感和多动。少

The causative gene of the ATRX syndrome, which maps on chromosome X and shows such phenotypes as mental retardation and α thalassemia, is clarified. It has been reported that intelligence is lowered when exon 2 is mutated. Then, in cooperation with Dr.En Li and Dr.H.Beppu (Harvard University, USA), we performed back-crossing in the C57BL6 mouse system from the 129 mouse system to six generations (N6) in order to produce the ATRX mutant mouse for behavioral analysis. Using the C75BL6, N6 generation mouse, the following results were obtained over the two-year research period from 2003 to 2004. (1) The mutant mice have kock in highly Lac Z gene at the mutation site. The Lac Z gene was well observed in the hippocampus, cerebral cortex and cerebellum by X-gal staining. (2) Immunostaining was carried out with an antibody that recognized the C-terminus of ATRX. As a result, in comparison with the wild type, the low expression of the ATRX protein in the cerebral cortex, cerebellum, and hippoca … More mpus was recognized in the ATRX mutant mouse. (3) Using the antibody that recognized the C-terminus of ATRX, the mutant mouse showed decreased protein expression of approximately 50% in brain tissues by Western blot, in comparison with the wild type. (4) It is well known that the hippocampus controls memory and learning. Therefore, in order to analyze its function, we examined spatial memory learning with the Morris water maze test, and found that memory and learning capability of the mutant mouse were inferior to those of the wild type. This finding was confirmed in the diet remuneration test under the environment which removed aquaphobia. We also performed the open field test and the home cage activity test in order to examine other behavioral disorders of the mutant mouse. From these tests, we noted hyperactivity in the mutant mouse. Although it was affected by bright light in the wild type mouse, the sojourn time in the light-dark environment was reversed in the mutant mouse. The behavioral analysis revealed that the ATRX mutant mouse presented with low learning capability, photophobia sensitivity and hyperactivity. Less