Two memory associated genes regulated by amyloid precursor protein intracellular domain Novel insights into the pathogenesis of learning and memory impairment in Alzheimer's disease

In this study, we employed chromatin immunoprecipitation, a useful method for studying the locations of transcription factors bound to specific DNA regions in specific cells, to investigate amyloid precursor protein intracellular domain binding sites in chromatin DNA from hippocampal neurons of rats, and to screen out five putative genes associated with the learning and memory functions. The promoter regions of the calcium/calmodulin-dependent protein kinase II alpha and glutamate receptor-2 genes were amplified by PCR from DNA products immunoprecipitated by amyloid precursor protein intracellular domain. An electrophoretic mobility shift assay and western blot analysis suggested that the promoter regions of these two genes associated with learning and memory were bound by amyloid precursor protein intracellular domain （in complex form）. Our experimental findings indicate that the amyloid precursor protein intracellular domain is involved in the transcriptional regulation of learning- and memory-associated genes in hippocampal neurons. These data may provide new insights into the molecular mechanism underlying the symptoms of progressive memory loss in Alzheimer＇s disease.

Novel Adaptors of Amyloid Precursor Protein Intracellular Domain and Their Functional Implications

Amyloid precursor protein intracellular domain （AICD） is one of the potential candidates in deciphering the complexity of Alzheimer＇s disease. It plays important roles in determining cell fate and neurodegeneration through its interactions with several adaptors. The pres- ence or absence of phosphorylation at specific sites determines the choice of partners. In this study, we identified 20 novel AICD- interacting proteins by in vitro pull down experiments followed by 2D gel electrophoresis and MALDI-MS analysis. The identified proteins can be grouped into different functional classes including molecular chaperones, structural proteins, signaling and transport molecules, adaptors, motor proteins and apoptosis determinants. Interactions of nine proteins were further validated either by colocal- ization using confocal imaging or by co-immunoprecipitation followed by immunoblotting. The cellular functions of most of the proteins can be correlated with AD. Hence, illustration of their interactions with AICD may shed some light on the disease pathophysiology.

β-淀粉样蛋白前体蛋白胞内结构域(AICD)研究进展

老年性痴呆症(Alzheimer's disease,AD)一个重要的病理学特征,是在神经细胞外形成由β-淀粉样蛋白(β-amyloid,Aβ)组成的淀粉样斑(amyloid plaques)。β-淀粉样蛋白前体蛋白(β-amyloid procursor protein,APP)经β-分泌酶和γ-分泌酶依次水解后产生Aβ和APP胞内结构域(APP intracellular domain,AICD)。现在已经知道Aβ在AD的发病机制中起着关键作用,但是关于AICD的生理及病理功能还不清楚。近年来研究发现AICD可以与细胞内多种蛋白相互作用,而且AICD在基因转录、细胞凋亡以及APP的加工和运输过程中均有调节功能。本文针对这一领域的研究进展,对AICD的生理及病理功能进行探讨。

淀粉样前体蛋白胞内域的功能和机制

Alzheimer's disease (AD),a degenerative neurological disorder,is the most common form of dementia among older people,whose symptoms include gradual memory loss,cognitive impairments and deterioration of language skills.Amyloid precursor protein (APP) is cleaved by serials of secretases and generates Aβ,sAPPα/β and APP intracellular domain (AICD).Aβ forms amyloid plaques,together with neurofibrillary tangles (NFTs) which is comprised with hyperphosphorylated tau,are hallmarks ofAD.Aβ,especially in its oligomeric form,plays important roles in AD,causing cell death,calcium influx,loss of spines and repression of long-term potentiation (LTP)[1].However,recent studies indicate that in addition to Aβ,other fragments of APP after its cleavage,such as AICD,play essential roles in AD as well.In this article,the function of AICD and its underlying mechanisms will be reviewed.