Limited understanding of species differences in kidney transporters is a critical knowledge gap for prediction of drug-induced acute kidney injury, drug interaction, and pharmacokinetics in humans. Here, we report protein abundance data of nineteen transporters in the kidney cortex across five species (human, monkey, dog, rat, and mouse). In general, the abundance of all the 19 membrane transporters was higher in preclinical species as compared to human except for MDR1, OCT3 and OCTN1. In nonhuman primate, the total abundance of 12 transporters for which absolute data were available, was 2.1-fold higher (p value = 0.025) relative to human but the % distribution of these transporters was identical in both species. MRP4, OCTN2, OAT2, Na+K+ATPase, MRP3, SGLT2, OAT1, MRP1, MDR1, OCT2 were expressed differently with cross-species variability of 8.2, 7.4, 6.1, 5.9, 5.4, 5.2, 4.1, 3.3 and 2.8-fold, respectively. Sex differences were only significant in rodents and dog. High protein-protein correlation was observed in OAT1 versus MRP2/MRP4 as well as OCT2 versus MATE1 in human and monkey. The cross-species and sex-dependent protein abundance data are important for animal to human scaling of drug clearance as well as for mechanistic understanding of kidney physiology and derisking of kidney toxicity for new therapeutic candidates in drug development. SIGNIFICANCE STATEMENT Prediction of drug-induced acute kidney injury, drug interaction, and pharmacokinetics in humans from animal data requires understanding of cross-species abundance of drug transporters in drug disposition relevant tissues, e.g., kidney, liver and intestine. We quantified protein abundance data of nineteen transporters in the kidney cortex across human, monkey, dog, rat, and mouse. Significant quantitative differences were observed in transporter abundance across species. Further, few transporters were only detected in specific species, e.g., OCT3 in human and BCRP in rodents. Moreover, several proteins (OAT1 versus MRP2/MRP4 and OCT2 versus MATE1) showed significant protein-protein correlations. These quantitative protein abundance data are important for mechanistic understanding of kidney toxicity and prediction of human renal drug clearance from animal data.

Background/Objectives: Sphingolipids are a class of lipids that play important structural and functional roles in the cell. Specific ceramide species are distinguishable through the fatty acid that is acylated to the sphingosine backbone, leading to distinct biological activities. Generally, long-chain (LC) ceramides (16:0 and 18:0) drive metabolic dysfunction resulting in the progression of different disease states, while very long-chain (VLC) ceramides (22:0 and 24:0) are thought to be either beneficial against disease progression or benign. In this study, we sought to alter the cellular composition of LC and VLC ceramides in ventricular HCMs to investigate how alterations in these lipids can affect the transcriptome of otherwise healthy HCMs. Methods: Here, we used specific siRNA to knockdown the ceramide synthases responsible for the production of LC and VLC ceramides in ventricular HCMs and investigated the changes in the transcriptome of HCMs with CERS2 or CERS5/6 silenced compared to control conditions. Results: Knocking down CERS2 led to an increase in cell death as well as widespread reductions in cellular VLC sphingolipids. Additionally, we demonstrated that VLC sphingolipid species may play a protective role in maintaining cardiovascular function and that reducing these lipids may contribute to cardiac dysfunction. Similarly, knocking down CERS5 and CERS6 led to reduced LC ceramides and also resulted in profound changes in gene transcription. Interestingly, multiple genes and pathways were affected in the opposite direction when compared to the changes observed with the CERS2 knockdown. Conclusions: Taken together, our results suggest pathways through which VLC ceramides may contribute to cardiac protection, and pathways where LC ceramides may promote HCM stress and the development of cardiac disease.