A new approach for developing a new drugs for alzheimer's disease (AD) and that for diagnosis for AD

由早老素2（PS2）基因转录本外显子5跳跃产生的异常剪接异构体（PS2 V）是散发性阿尔茨海默病（AD）的诊断特征。我们发现PS2 V在人神经母细胞瘤SK-N-SH细胞中是缺氧诱导的。我们纯化了一个负责任的反式作用因子的基础上结合的外显子5片段。该因子被鉴定为高迁移率族A1 a（HMGA 1a）蛋白。HMGA 1a与位于5'剪接位点上游的外显子5上的特定序列结合。缺氧诱导HMGA 1a表达，并在内源性剪接因子SC 35的作用下在核斑点中积累。HMGA 1a的过表达产生PS2 V，但是PS2 V通过与对HMGA 1a具有强亲和力的U1 snRNP 70 K蛋白共转染而被抑制。HMGA 1a可干扰U1 snRNP与5'剪接位点的结合，引起外显子5跳跃。抑制HMGA 1a与PS 2外显子5的结合可抑制内质网应激引起的神经元死亡 ...更多信息 提示有可能开发一种治疗AD的新药。此外，我们发现，人cappase-4，一个caspase-1亚家族的成员，包括caspase-12，是本地化的ER膜，并被切割时，细胞与ER应激诱导剂，而不是其他凋亡试剂处理的脑组织中的HMGA 1a水平显着增加。caspase-4的裂解不受Bcl-2过表达的影响，Bcl-2过表达阻止线粒体上的信号转导，这表明caspase-4主要在ER应激诱导的细胞凋亡中被激活。此外，小干扰RNA减少caspase-4的表达减少ER应激诱导的细胞凋亡在一些细胞系，但不是其他ER应激非依赖性细胞凋亡。Caspase-4也可通过A β给药裂解，并且A β诱导的细胞凋亡可通过小干扰RNA减少至Caspase-4。本研究还发现散发性AD患者脑脊液中PS_2V水平明显高于对照组，提示PS_2V水平的变化对散发性AD的诊断有一定意义。

The aberrant splicing isoform (PS2V), generated by exon 5 skipping of the presenilin2 (PS2) gene transcript, is a diagnostic feature of sporadic Alzheimer's disease (AD). We found PS2V is hypoxia-inducible in human neuroblastoma SK-N-SH cells. We purified a responsible trans-acting factor based on its binding to an exon 5 fragment. The factor was identified as the high mobility group A1a (HMGA1a) protein. HMGA1a bound to a specific sequence on exon 5, located upstream of the 5' splice site. HMGA1a expression was induced by hypoxia and the protein was accumulated in the nuclear speckles with the endogenous splicing factor SC35. Overexpression of HMGA1a generated PS2V, but PS2V was repressed by cotransfection with the U1 snRNP 70K protein that has a strong affinity to HMGA1a. HMGA1a could interfere with U1 snRNP binding to the 5' splice site and caused exon 5 skipping. Inhibition of the binding of HMGA1a to PS2exon 5 inhibited the neuronal death caused by ER (endoplasmi reticulum) stress … More , suggesting the possibility to develop a new drug for AD. Furthermore, HMGA1a levels were significantly increased in the brain tissue from sporadic AD patients.In addition, we found that human cappase-4, a member of caspase-1 subfamily that includes caspase-12, is localized to the ER membrane, and is cleaved when cells are treated with ER stress-inducing reagents, but not other apoptotic reagents. Cleavage of caspase-4 is not affected by overexpression of Bcl-2, which prevents signal transduction on the mitochondria, suggesting that caspase-4 is primarily activated in ER stress-induced apoptosis. Furthermore, a reduction of caspase-4 expression by small interfering RNA decreases ER stress-induced apoptosis in some cell lines, but not other ER stress-independent apoptosis. Caspase-4 is also cleaved by administration of A β and A β-induced apoptosis is reduced by small interfering RNAs to caspase-4. Thus is involved in pathogenesis of AD, and inhibition of caspase-4 may leads to develop a new drug for AD.We also found the high level of PS2V in cerebrospinal fluid of sporadic AD comparing with that of control, showing that alteration of PS2V level is useful for diagnosis of sporadic AD Less