RT Journal Article
SR Electronic
T1 Aβ40 Reduces P-Glycoprotein at the Blood–Brain Barrier through the Ubiquitin–Proteasome Pathway
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 1930
OP 1941
DO 10.1523/JNEUROSCI.0350-15.2016
VO 36
IS 6
A1 Anika M.S. Hartz
A1 Yu Zhong
A1 Andrea Wolf
A1 Harry LeVine III
A1 David S. Miller
A1 Björn Bauer
YR 2016
UL http://www.jneurosci.org/content/36/6/1930.abstract
AB Failure to clear amyloid-β (Aβ) from the brain is in part 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 the luminal plasma membrane of the brain capillary endothelium. P-gp is reduced at the blood–brain barrier in AD, which has been shown to be associated with Aβ brain accumulation. However, the mechanism responsible for P-gp reduction in AD is not well understood. Here we focused on identifying critical mechanistic steps involved in reducing P-gp in AD. We exposed isolated rat brain capillaries to 100 nm Aβ40, Aβ40, aggregated Aβ40, and Aβ42. We observed that only Aβ40 triggered reduction of P-gp protein expression and transport activity levels; this occurred in a dose- and time-dependent manner. To identify the steps involved in Aβ-mediated P-gp reduction, we inhibited protein ubiquitination, protein trafficking, and the ubiquitin–proteasome system, and monitored P-gp protein expression, transport activity, and P-gp-ubiquitin levels. Thus, exposing brain capillaries to Aβ40 triggers ubiquitination, internalization, and proteasomal degradation of P-gp. These findings may provide potential therapeutic targets within the blood–brain barrier to limit P-gp degradation in AD and improve Aβ brain clearance.SIGNIFICANCE STATEMENT The mechanism reducing blood–brain barrier P-glycoprotein (P-gp) in Alzheimer's disease is poorly understood. In the present study, we focused on defining this mechanism. We demonstrate that Aβ40 drives P-gp ubiquitination, internalization, and proteasome-dependent degradation, reducing P-gp protein expression and transport activity in isolated brain capillaries. These findings may provide potential therapeutic avenues within the blood–brain barrier to limit P-gp degradation in Alzheimer's disease and improve Aβ brain clearance.