Abstract

Alzheimer's disease (AD) is the leading cause of dementia and mitigating amyloid-ß (Aß) levels may serve as a rational therapeutic avenue to slow AD progression. Pharmacologic inhibition of the Rho-associated protein kinases (ROCK1 and ROCK2) is proposed to curb Aß levels, and mechanisms that underlie ROCK2's effects on Aß production are defined. How ROCK1 affects Aß generation remains a critical barrier. Here, we report that ROCK1 protein levels were elevated in mild cognitive impairment due to AD (MCI) and AD brains compared to controls. Aß42 oligomers marginally increased ROCK1 and ROCK2 protein levels in neurons but strongly induced phosphorylation of Lim kinase 1 (LIMK1), suggesting that Aß42 activates ROCKs. RNAi depletion of ROCK1 or ROCK2 suppressed endogenous Aß40 production in neurons, and Aß40 levels were reduced in brains of ROCK1 heterozygous knock-out mice compared to wild-type littermate controls. ROCK1 knockdown decreased amyloid precursor protein (APP), and treatment with bafilomycin accumulated APP levels in neurons depleted of ROCK1. These observations suggest that reduction of ROCK1 diminishes Aß levels by enhancing APP protein degradation. Collectively, these findings support the hypothesis that both ROCK1 and ROCK2 are therapeutic targets to combat Aß production in AD. Mitigating amyloid-ß (Aß) levels is a rational strategy for Alzheimer's disease (AD) treatment, however, therapeutic targets with clinically available drugs are lacking. We hypothesize that Aß accumulation in mild cognitive impairment because of AD (MCI) and AD activates the RhoA/ROCK pathway which in turn fuels production of Aß. Escalation of this cycle over the course of many years may contribute to the buildup of amyloid pathology in MCI and/or AD.

View details for DOI 10.1111/jnc.13688

View details for PubMedID 27246255

View details for PubMedCentralID PMC4980252