Functional role and regulation of permeability‐glycoprotein (P‐gp) in the fetal membrane during drug transportation
Ananthkumar Kammala, Meagan Benson, Esha Ganguly, Lauren Richardson, Ramkumar Menon
Abstract
Abstract Objective Na + /H + exchange regulatory factor‐1 (NHERF‐1) is a class I PDZ (PSD95/Discs‐large/ZO‐1) binding protein involved in cell‐surface expression and stabilization of transporter proteins, including permeability‐glycoprotein (P‐gp) in various cell types. P‐gp, expressed in placental trophoblasts, is an efflux transporter protein that influences the pharmacokinetics of various drugs used during pregnancy. Previously we have reported that NHERF‐1 regulates fetal membrane inflammation. However, the role of NHERF‐1 in regulating P‐gp in the fetal membrane during drug transportation remains unclear. This study determined the interplay between NHERF‐1 and P‐gp in human fetal membrane cells. Methods Fetal membranes from normal, term cesareans were screened for P‐gp by immunohistochemistry (IHC). Chorionic trophoblast (CTC), with the highest expression of P‐gp among fetal membrane cells, was further used to test interactive properties between NHERF‐1 and P‐gp. BeWo (placental trophoblast cell line) cells were used as a control. Immunoprecipitation (IP) of CTC lysates using the P‐gp antibody followed by western blot determined co‐precipitation of NHERF‐1. Silencing NHERF‐1 using small interfering RNA further tested the relevance of NHERF‐1 in P‐gp expression and function in CTC and BeWo cells. NHERF‐1 regulation of P‐gp's efflux function (drug resistance) was further tested using the ENZO TM efflux dye kit. Results Immunohistochemistry localized, and western blot confirmed P‐gp in human fetal membranes, primarily in the CTC with limited expression in the amnion epithelial layer. P‐gp expression in the membranes was similar to that seen in the placenta. IP data showed P‐gp co‐precipitating with NHERF1. Silencing of NHERF‐1 resulted in significant drug resistance suggesting P‐gp function mediated through NHERF1 in CTCs. Conclusion Proinflammatory mediator NHERF‐1 regulates P‐gp and control drug transportation across the fetal membranes. Our data suggest a novel functional role for fetal membranes during pregnancy. Besides the placenta, fetal membranes may also regulate efflux of materials at the feto‐maternal interface and control drug transport during pregnancy.