Protecting P-glycoprotein at the blood–brain barrier from degradation in an Alzheimer’s disease mouse model

Fluids and Barriers of the CNS

Björn Bauer¹  Andrea Baldeshwiler²  Yujie Ding³  Yu Zhong³  Erin L. Abner⁴  Anika M. S. Hartz⁵ 

[1] Department of Pharmacology and Nutritional Sciences, University of Kentucky, 40536, Lexington, KY, USA;Department of Pharmacy Practice and Pharmaceutical Sciences, College of Pharmacy, University of Minnesota, 55812, Duluth, Minnesota, USA;Sanders-Brown Center on Aging, University of Kentucky, 40536, Lexington, KY, USA;Sanders-Brown Center on Aging, University of Kentucky, 40536, Lexington, KY, USA;Department of Epidemiology, College of Public Health, University of Kentucky, 40536, Lexington, KY, USA;Sanders-Brown Center on Aging, University of Kentucky, 40536, Lexington, KY, USA;Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 40536, Lexington, KY, USA;University of Kentucky Sanders-Brown Center on Aging, 800 S Limestone, 40536, Lexington, KY, USA;

关键词: Blood–brain barrier;    P-glycoprotein;    Alzheimer’s disease;    Brain capillaries;    Amyloid beta;    Ubiquitin-proteasome system;   

DOI  :  10.1186/s12987-021-00245-4

来源: Springer

【 摘 要 】

BackgroundFailure to clear Aβ from the brain is partly responsible for Aβ brain accumulation in Alzheimer’s disease (AD). A critical protein for clearing Aβ across the blood-brain barrier is the efflux transporter P-glycoprotein (P-gp). In AD, P-gp levels are reduced, which contributes to impaired Aβ brain clearance. However, the mechanism responsible for decreased P-gp levels is poorly understood and there are no strategies available to protect P-gp. We previously demonstrated in isolated brain capillaries ex vivo that human Aβ40 (hAβ40) triggers P-gp degradation by activating the ubiquitin-proteasome pathway. In this pathway, hAβ40 initiates P-gp ubiquitination, leading to internalization and proteasomal degradation of P-gp, which then results in decreased P-gp protein expression and transport activity levels. Here, we extend this line of research and present results from an in vivo study using a transgenic mouse model of AD (human amyloid precursor protein (hAPP)-overexpressing mice; Tg2576).MethodsIn our study, hAPP mice were treated with vehicle, nocodazole (NCZ, microtubule inhibitor to block P-gp internalization), or a combination of NCZ and the P-gp inhibitor cyclosporin A (CSA). We determined P-gp protein expression and transport activity levels in isolated mouse brain capillaries and Aβ levels in plasma and brain tissue.ResultsTreating hAPP mice with 5 mg/kg NCZ for 14 days increased P-gp levels to levels found in WT mice. Consistent with this, P-gp-mediated hAβ42 transport in brain capillaries was increased in NCZ-treated hAPP mice compared to untreated hAPP mice. Importantly, NCZ treatment significantly lowered hAβ40 and hAβ42 brain levels in hAPP mice, whereas hAβ40 and hAβ42 levels in plasma remained unchanged.ConclusionsThese findings provide in vivo evidence that microtubule inhibition maintains P-gp protein expression and transport activity levels, which in turn helps to lower hAβ brain levels in hAPP mice. Thus, protecting P-gp at the blood-brain barrier may provide a novel therapeutic strategy for AD and other Aβ-based pathologies.

【 授权许可】

CC BY