Tranter, J. D. | Search bioRxiv

bioRxiv2020

Transfer of hepatocellular microRNA regulates cytochrome P450 2E1 in renal tubular cells

Extracellular microRNAs have been demonstrated to have the ability to enter kidney tubular cells and modify gene expression. We have used a Dicer-hepatocyte-specific microRNA conditional knock-out (Dicer-CKO) mouse to investigate functional microRNA transfer from liver to kidney under physiological conditions and in the context of drug toxicity. Dicer-CKO mice demonstrated a time-dependent decrease in the hepatocyte-derived microRNA, miR-122, in the kidney in the absence of other microRNA changes. During hepatotoxicity, miR-122 increased in kidney tubular cells; this was abolished in Dicer-CKO mice. Depletion of hepatocyte microRNAs increased expression and activity of the miR-122 target - cytochrome (CYP) P450 2E1 - in the kidney. Serum extracellular vesicles (ECVs) from mice with hepatotoxicity increased proximal tubular cell miR-122 and prevented cisplatin proximal tubular cell toxicity. miR-122 also increased in urinary ECVs during hepatotoxicity in humans. Transfer of microRNA was not restricted to liver injury - we detected miR-499 release with murine cardiac injury, and this correlated with an increase in the kidney. In summary, a physiological transfer of microRNA to the kidney exists, which is increased by liver injury. Regulation of renal drug response due to signalling by microRNA of hepatic origin represents a new paradigm for understanding and preventing nephrotoxicity.

pharmacology and toxicology↗

bioRxiv2019

Direct detection of circulating microRNA-122 using dynamic chemical labelling with single molecule detection overcomes stability and isomiR challenges for biomarker qualification

Circulating microRNAs are biomarkers reported to be stable and translational across species. miR-122 (miR-122-5p) is a hepatocyte-specific microRNA biomarker for drug-induced liver injury (DILI). Our objective was to develop an extraction-free and amplification-free detection method for measuring miR-122 that has translational utility in context of DILI. We developed a single molecule dynamic chemical labelling (DCL) assay based on miR-122 hybridization to an abasic peptide nucleic acid probe that contained a reactive amine instead of a nucleotide at a specific position in the sequence. The single molecule DCL assay specifically measured miR-122 directly from 10 {micro}L of serum or plasma without any extraction steps, with a fit-for-purpose limit of detection of 1.32 pM. In 192 human serum samples, DCL accurately identified patients at risk of DILI (area under ROC curve 0.98 (95%CI 0.96-1), P<0.0001). The miR-122 assay also quantified liver injury in rats and dogs. When DCL beads were added to serum, the miR-122 signal was stabilised (no loss of signal after 14 days at room temperature). By contrast, there was substantial degradation of miR-122 in the absence of beads ({approx}60% lost in 1 day). RNA sequencing demonstrated the presence of multiple miR-122 isomiRs with DILI that were at low concentration or not present in healthy patient serum. Sample degradation over time produced more isomiRs, particularly rapidly with DILI. PCR was inaccurate when analysing miR-122 isomiRs, whereas the DCL assay demonstrated accurate quantification. In summary, the DCL assay can accurately measure miR-122 directly from serum and plasma to diagnose liver injury in humans and other species, and can overcome important microRNA biomarker analytical and biological challenges.

pharmacology and toxicology↗