A Comprehensive Analysis of Ontogeny of Renal Drug Transporters: mRNA Analyses, Quantitative Proteomics, and Localization

Abstract

Human renal membrane transporters play key roles in the disposition of renally cleared drugs and endogenous substrates, but their ontogeny is largely unknown. Using 184 human postmortem frozen renal cortical tissues (preterm newborns to adults) and a subset of 62 tissue samples, we measured the mRNA levels of 11 renal transporters and the transcription factor pregnane X receptor (PXR) with quantitative real-time polymerase chain reaction, and protein abundance of nine transporters using liquid chromatography tandem mass spectrometry selective reaction monitoring, respectively. Expression levels of p-glycoprotein, urate transporter 1, organic anion transporter 1, organic anion transporter 3, and organic cation transporter 2 increased with age. Protein levels of multidrug and toxin extrusion transporter 2-K and breast cancer resistance protein showed no difference from newborns to adults, despite age-related changes in mRNA expression. Multidrug and toxin extrusion transporter 1, glucose transporter 2, multidrug resistance-associated protein 2, multidrug resistance-associated protein 4 (MRP4), and PXR expression levels were stable. Using immunohistochemistry, we found that MRP4 localization in pediatric samples was similar to that in adult samples. Collectively, our study revealed that renal drug transporters exhibited different rates and patterns of maturation, suggesting that renal handling of substrates may change with age.

Incorporating Ontogeny in Physiologically Based Pharmacokinetic Modeling to Improve Pediatric Drug Development: What We Know About Developmental Changes in Membrane Transporters

“…Further studies are warranted to investigate this lack of gene‐protein correlation, as only 1 term neonate was included for the proteomic analysis in that study MATE1 and MATE2‐K : mRNA and protein levels of MATE1 were independent of age . Although the transcript level of MATE2‐K in term newborns was significantly lower than that in adults, the protein level was found to be comparable across all the age groups studied from term newborn to adults.…”

“…Gene expression of 11 transporters was analyzed from a total of 184 frozen human renal cortical samples from preterm newborn to 75 years of age. The protein expression of 9 transporters and localization of MRP4 using immunohistochemistry were also studied using a subset of the kidney samples BCRP : The mRNA level of BCRP was significantly higher in term neonates compared with other age groups, but the protein abundance appeared to be comparable across all age groups from term neonates to adults.…”

“… BCRP : The mRNA level of BCRP was significantly higher in term neonates compared with other age groups, but the protein abundance appeared to be comparable across all age groups from term neonates to adults. Further studies are warranted to investigate this lack of gene‐protein correlation, as only 1 term neonate was included for the proteomic analysis in that study MATE1 and MATE2‐K : mRNA and protein levels of MATE1 were independent of age .…”

“…Interestingly, proper MRP4 localization was detected as early as gestational age 27 weeks, postnatal 9 days old. This result appeared to accompany the stable gene expression during development Uric acid transporter 1 (URAT1) : The mRNA and protein abundance of URAT1 increased with age from term newborn to adults …”

“…This result appeared to accompany the stable gene expression during development Uric acid transporter 1 (URAT1) : The mRNA and protein abundance of URAT1 increased with age from term newborn to adults P‐gp : Similarly to those of the liver and intestine, the ontogeny of renal P‐gp was studied relatively extensively.…”