Early Signaling Events in Renal Compensatory Hypertrophy Revealed by Multi-Omics

Loss of a kidney results in compensatory growth of the remaining kidney, a phenomenon of considerable clinical importance. However, the mechanisms involved are largely unknown. Here, we used a multi-omic approach in a mouse unilateral nephrectomy model to identify signaling processes associated with compensatory hypertrophy of the renal proximal tubule. Morphometry applied to microdissected proximal tubules showed that growth of the proximal tubule involves a marked, rapid increase in cell volume rather than cell number. Measurements of DNA accessibility (ATAC-seq), transcriptome (RNA-seq) and proteome (quantitative protein mass spectrometry) independently identified patterns of change that are indicative of activation of the lipid-regulated transcription factor, PPARα. Activation of PPARα by fenofibrate administration increased proximal tubule cell size, while genetic deletion of PPARα in mice decreased it. The results indicate that PPARα is an important determinant of proximal tubule cell size and is a likely mediator of compensatory proximal tubule hypertrophy.