1α,25-Dihydroxyvitamin D3-liganded vitamin D receptor increases expression and transport activity of P-glycoprotein in isolated rat brain capillaries and human and rat brain microvessel endothelial cells

Authors

  • Matthew R. Durk,

    1. Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
    Search for more papers by this author
  • Gary N.Y. Chan,

    1. Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
    Search for more papers by this author
  • Christopher R. Campos,

    1. Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
    Search for more papers by this author
  • John C. Peart,

    1. Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
    Search for more papers by this author
  • Edwin C. Y. Chow,

    1. Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
    Search for more papers by this author
  • Eason Lee,

    1. Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
    Search for more papers by this author
  • Ronald E. Cannon,

    1. Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
    Search for more papers by this author
  • Reina Bendayan,

    1. Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
    Search for more papers by this author
  • David S. Miller,

    1. Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, USA
    Search for more papers by this author
  • K. Sandy Pang

    Corresponding author
    • Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
    Search for more papers by this author

Address correspondence and reprint requests to Dr K. Sandy Pang, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario, Canada M5S 3M2. E-mail: ks.pang@utoronto.ca

Abstract

Induction of the multidrug resistance protein 1 (MDR1)/P-glycoprotein (P-gp) by the vitamin D receptor (VDR) was investigated in isolated rat brain capillaries and rat (RBE4) and human (hCMEC/D3) brain microvessel endothelial cell lines. Incubation of isolated rat brain capillaries with 10 nM of the VDR ligand, 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3] for 4 h increased P-gp protein expression fourfold. Incubation with 1,25(OH)2D3 for 4 or 24 h increased P-gp transport activity (specific luminal accumulation of NBD-CSA, the fluorescent P-gp substrate) by 25–30%. In RBE4 cells, Mdr1b mRNA was induced in a concentration-dependent manner by exposure to 1,25(OH)2D3. Concomitantly, P-gp protein expression increased 2.5-fold and was accompanied by a 20–35% reduction in cellular accumulation of the P-gp substrates, rhodamine 6G (R6G), and HiLyte Fluor 488-labeled human amyloid beta 1-42 (hAβ42). In hCMEC/D3 cells, a 3 day exposure to 100 nM 1,25(OH)2D3 increased MDR1 mRNA expression (40%) and P-gp protein (threefold); cellular accumulation of R6G and hAβ42 was reduced by 30%. Thus, VDR activation up-regulates Mdr1/MDR1 and P-gp protein in isolated rat brain capillaries and rodent and human brain microvascular endothelia, implicating a role for VDR in increasing the brain clearance of P-gp substrates, including hAβ42, a plaque-forming precursor in Alzheimer's disease.

Ancillary