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

Abstract

MDR1/P-gp induction 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 (4-fold). 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 three day exposure to 100 nM 1,25(OH)2D3 increased MDR1 mRNA expression (40%) and P-gp protein (3-fold); 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.

Aging alters mRNA expression of amyloid transporter genes at the blood-brain barrier

“…It appears that activation of P-gp protein is preceded by an increase in P-gp mRNA which is also associated with activation of the nuclear factor kappa B (NF-kB) (Zhang et al 2014; Fan et al 2015). In isolated rat and human brain microvessel endothelium, vitamin D3-liganded vitamin D receptor increases P-gp mRNA expression and increases P-gp transporter expression (Durk et al 2012). It has been shown that fetal expression of P-gp is very high and falls progressively with age in the post-natal period.…”

Temporal changes in tissue 1α,25-dihydroxyvitamin D3, vitamin D receptor target genes, and calcium and PTH levels after 1,25(OH)2D3treatment in mice

“…VDRresponsive transporters include the rat apical sodium-dependent bile acid transporter (Asbt) (10), human organic aniontransporting polypeptide (OATP1A2) (21), multidrug resistance protein-1 or P-glycoprotein (MDR1/P-gp) (44), and the human and rodent multidrug resistance-associated proteins (MRP2/Mrp2, Mrp3, MRP4/Mrp4) both in vitro and in vivo (14,22). Our laboratory has shown that VDR transactivates P-gp in brain microvessel endothelia (18) in vitro and P-gp in murine kidney and brain but not ileum and liver in vivo, leading to hastened efflux of digoxin in the brain and kidney (11).…”

In Vitro Cerebrovascular Modeling in the 21st Century: Current and Prospective Technologies

“…, insulin, transferrin, leptin); bi) absorptive mediated transcytosis ( e.g. , albumin) and active transport systems for glucose and other essential nutrients (aminoacids); c) transport activity of P-gp in response to Vitamin D (93); d) modulatory mechanisms of blood-brain barrier P-gp transport activity (94); and e) transendothelial transport of fluorescent drugs by confocal microscopy (95). In addition, these brain microvessels once purified are a viable source of brain microvascular endothelial cells which can be isolated from these microvessel fragments allowing the preparation of a relatively pure BBB endothelial primary culture (96).…”