The Renal Micro-RNA Expression Profile of Pkd1RC/RC Mice Changes Longitudinally with the Progression of the Disease

Experimental autosomal dominant polycystic kidney disease is associated with longitudinal changes in the kidney micro-RNA and mRNA profiles. Alterations in cellular transport, a feature of CKD, and a common biological process within polycystic kidney disease models and human autosomal dominant polycystic kidney disease, is present from early stages. Early versus late micro-RNA expression changes in autosomal dominant polycystic kidney disease could be targeted for a more tailored therapeutic intervention in the disease.

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the progressive development and enlargement of bilateral kidney cysts, which often leads to kidney failure. This study comprehensively characterized the expression profile of micro-RNAs (miRNAs) and their target genes in Pkd1RC/RC mice and further compared them with other murine models of polycystic kidney disease (PKD) and a model of CKD and individuals with ADPKD.

Pkd1RC/RC and wild-type (WT) mice ( n =10 each, five males and five females) were studied at 1, 6, and 12 months. At each time point, kidney volume was determined in vivo (magnetic resonance imaging), followed by ex vivo histomorphometric analyses. In randomly selected Pkd1RC/RC and WT mouse kidneys ( n =5/genotype, at 1 and 12 months), miRNA-sequencing (seq) was performed, followed by mRNA-seq, integrated (miRNA-seq/mRNA-seq analysis), and functional analysis of miRNA target genes. Venn diagrams were constructed to identify overlapping and novel differentially expressed (DE) miRNAs in Pkd1RC/RC and other commonly used murine models of PKD, diabetic kidney disease, and individuals with ADPKD.

miRNA-seq analysis identified 41 and 181 miRNAs DE in Pkd1RC/RC versus WT kidneys at 1 and 12 months, respectively, which were confirmed by quantitative PCR. Target genes of miRNAs DE in Pkd1RC/RC at early stages encoded for proteins mainly implicated in cell proliferation and α -ketoglutarate ( α -KG) transport, whereas those DE at late stages encoded for transport proteins involved in proinflammatory and metabolic processes. Urine α -KG concentration ( 1 H nuclear magnetic resonance spectroscopy), its fractional excretion, and tissue levels were higher in Pkd1RC/RC during the entire course of the disease and associated with decreased protein expression of α -KG transporters sodium-coupled dicarboxylate transporter 3 and organic anion transporter 1. We further identified common DE miRNAs among murine models of PKD, diabetic kidney disease, and previous reports in individuals with ADPKD, as well as several novel miRNAs DE in early and late Pkd1RC/RC kidneys, which have not been previously reported in either other murine models of PKD or patients with ADPKD.

Our study demonstrates that the renal miRNA expression profile changes longitudinally with the progression of the disease and might suggest that the post-transcriptional regulation of α -KG transport could represent a novel early feature of the disease.