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Functional Expression of Multidrug-Resistance (MDR) Transporters in Developing Human Fetal Brain Endothelial Cells
Phetcharawan Lye1,2, Enrrico Bloise1,2,3, Guinever E Imperio2
1Department of Physiology, University of Toronto, Toronto, ON M5S 1A8, Canada.
Insights
Multidrug resistance transporters P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are functionally expressed in developing human brain endothelial cells. These transporters contribute to the blood-brain barrier
Area of Science:
- Neuroscience
- Pharmacology
- Developmental Biology
Background:
- Limited information exists on multidrug resistance (MDR) transporters in the developing blood-brain barrier (BBB).
- P-glycoprotein (P-gp, ABCB1) and breast cancer resistance protein (BCRP/ABCG2) are key MDR transporters.
- Understanding their role in early development is crucial for neuroprotection.
Purpose of the Study:
- To investigate the functional expression and activity of P-gp and BCRP in primary human fetal brain endothelial cells (hfBECs) during development.
- To assess the impact of gestational age on the expression and function of these transporters.
- To determine the contribution of these transporters to the protective phenotype of the developing BBB.
Main Methods:
- Isolation and culture of primary hfBECs from early and mid-gestation human fetal brains.
- Immunolocalization of endothelial cell markers (von Willebrand factor) and tight junction proteins (zonula occludens-1, claudin-5).
- Assessment of P-gp and BCRP expression (immunostaining, protein/mRNA levels) and function (activity assays).
- Evaluation of capillary-like tube formation capability.
Main Results:
- hfBECs from both early and mid-gestation expressed endothelial cell markers and formed capillary-like tubes.
- P-gp and BCRP were detected in hfBECs, localized in capillary-like tubes, cytoplasm, and nucleus.
- P-gp protein levels and ABCB1 mRNA decreased from early to mid-gestation (p < 0.05).
- BCRP protein levels also decreased from early to mid-gestation.
- No significant differences in P-gp or BCRP activity were observed between the two gestational groups.
Conclusions:
- Primary human fetal brain endothelial cells express functionally competent P-gp and BCRP drug transporters.
- These transporters are present from early stages of gestation.
- The findings suggest that P-gp and BCRP contribute to the protective phenotype of the developing blood-brain barrier in the conceptus.
Abstract:
There is little information about the functional expression of the multidrug resistance (MDR) transporters P-glycoprotein (P-gp, encoded by ABCB1) and breast cancer resistance protein (BCRP/ABCG2) in the developing blood−brain barrier (BBB). We isolated and cultured primary human fetal brain endothelial cells (hfBECs) from early and mid-gestation brains and assessed P-gp/ABCB1 and BCRP/ABCG2 expression and function, as well as tube formation capability. Immunolocalization of the von Willebrand factor (marker of endothelial cells), zonula occludens-1 and claudin-5 (tight junctions) was detected in early and mid-gestation-derived hfBECs, which also formed capillary-like tube structures, confirming their BEC phenotype. P-gp and BCRP immunostaining was detected in capillary-like tubes and in the cytoplasm and nucleus of hfBECs. P-gp protein levels in the plasma membrane and nuclear protein fractions, as well as P-gp protein/ABCB1 mRNA and BCRP protein levels decreased (p < 0.05) in hfBECs, from early to mid-gestation. No differences in P-gp or BCRP activity in hfBECs were observed between the two age groups. The hfBECs from early and mid-gestation express functionally competent P-gp and BCRP drug transporters and may thus contribute to the BBB protective phenotype in the conceptus from early stages of pregnancy.
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