Other Publications (1)
Articles by Andrew N. Shen in JoVE
Isolation of Cerebral Capillaries from Fresh Human Brain Tissue Anika M.S. Hartz1, Julia A. Schulz2, Brent S. Sokola2, Stephanie E. Edelmann1, Andrew N. Shen1, Ralf G. Rempe2, Yu Zhong1, Nader El Seblani3, Bjoern Bauer2 1Sanders-Brown Center on Aging, Department of Pharmacology and Nutritional Sciences, University of Kentucky, 2Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 3Department of Neuroscience, University of Kentucky Isolated brain capillaries from human brain tissue can be used as a preclinical model to study barrier function under physiological and pathophysiological conditions. Here, we present an optimized protocol to isolate brain capillaries from fresh human brain tissue.
Other articles by Andrew N. Shen on PubMed
Preventing P-gp Ubiquitination Lowers Aβ Brain Levels in an Alzheimer's Disease Mouse Model Frontiers in Aging Neuroscience. 2018 | Pubmed ID: 29997495 One characteristic of Alzheimer's disease (AD) is excessive accumulation of amyloid-β (Aβ) in the brain. Aβ brain accumulation is, in part, due to a reduction in Aβ clearance from the brain across the blood-brain barrier. One key element that contributes to Aβ brain clearance is P-glycoprotein (P-gp) that transports Aβ from brain to blood. In AD, P-gp protein expression and transport activity levels are significantly reduced, which impairs Aβ brain clearance. The mechanism responsible for reduced P-gp expression and activity levels is poorly understood. We recently demonstrated that Aβ triggers P-gp degradation through the ubiquitin-proteasome pathway. Consistent with these data, we show here that ubiquitinated P-gp levels in brain capillaries isolated from brain samples of AD patients are increased compared to capillaries isolated from brain tissue of cognitive normal individuals. We extended this line of research to studies using transgenic human amyloid precursor protein (hAPP)-overexpressing mice (Tg2576) that were treated with PYR41, a cell-permeable, irreversible inhibitor of the ubiquitin-activating enzyme E1. Our data show that inhibiting P-gp ubiquitination protects the transporter from degradation, and immunoprecipitation experiments confirmed that PYR41 prevented P-gp ubiquitination. We further found that PYR41 treatment prevented reduction of P-gp protein expression and transport activity levels and substantially lowered Aβ brain levels in hAPP mice. Together, our findings provide proof that the ubiquitin-proteasome system mediates reduction of blood-brain barrier P-gp in AD and that inhibiting P-gp ubiquitination prevents P-gp degradation and lowers Aβ brain levels. Thus, targeting the ubiquitin-proteasome system may provide a novel therapeutic approach to protect blood-brain barrier P-gp from degradation in AD and other Aβ-based pathologies.