A CRISPR/Cas9 based strategy to manipulate the Alzheimer’s amyloid pathway

The gradual accumulation of amyloid-{beta} (A{beta}) is a neuropathologic hallmark of Alzheimers disease (AD); playing a key role in disease progression. A{beta} is generated by the sequential cleavage of amyloid precursor protein (APP) by {beta}- and {gamma}-secretases, with BACE-1 ({beta}-site APP cleaving enzyme-1) cleavage as the rate limiting step 1-3. CRISPR/Cas9 guided gene-editing is emerging as a promising tool to edit pathogenic mutations and hinder disease progression 4,5,6 However, few studies have applied this technology to neurologic diseases 7-9. Besides technical caveats such as low editing efficiency in brains and limited in vivo validation 7, the canonical approach of mutation-correction would only be applicable to the small fraction of neurodegenerative cases that are inherited (i.e. < 10% of AD, Parkinsons, ALS); with a new strategy needed for every gene. Moreover, feasibility of CRISPR/Cas9 as a therapeutic possibility in sporadic AD has not been explored. Here we introduce a strategy to edit endogenous APP at the extreme C-terminus and reciprocally manipulate the amyloid pathway - attenuating {beta}-cleavage and A{beta}, while up-regulating neuroprotective a-cleavage. APP N-terminus, as well as compensatory APP homologues remain intact, and key physiologic parameters remain unaffected. Robust APP-editing is seen in cell lines, cultured neurons, human embryonic stem cells/iPSC-neurons, and mouse brains. Our strategy works by limiting the physical association of APP and BACE-1, and we also delineate the mechanism that abrogates APP/BACE-1 interaction in this setting. Our work offers an innovative cut and silence gene-editing strategy that could be a new therapeutic paradigm for AD.