hURAT1Transgenic Mouse Model for Evaluating Targeted Urate-Lowering Agents

Abstract

AbstractObjectiveUrate transporter 1 (URAT1), a well-established urate-lowering therapeutic target for hyperuricemia and gout treatment, expresses in the kidney proximal tubule and is responsible for uric acid (UA) reabsorption. However, non-primate animal models currently used in pharmacological studies failed to evaluate URAT1 inhibitor’s effectiveness because their URAT1 has a very low UA affinity compared to human URAT1, resulting in a lag in targeting drug screening and novel therapy development for gout treatment. We established a human URAT1 (hURAT1) transgenic knock-in (KI) mouse model to assess uricosuric agents’ effectiveness and characterize URAT1-caused pathogenesis.MethodsWe generatedhURAT1transgenic mice using CRISPR/Cas9 knock-in technique.mUrat1knockout was achieved by replacing exon 1 coding sequence with a humanSLC22A12CDS-pA cassette. Based on the above transgenic mice, a hyperuricemia model was further established by hypoxanthine administration.ResultsThehURAT1-KI mice successfully expressed hURAT1 protein to the apical side of the kidney proximal tubule epithelium, where a native human URAT1 kidney localization in human body. Upon hypoxanthine challenge, the blood UA level was elevated inhURAT1-KI mice, exhibiting an approximately 37% increase compared towild-type (WT)mice. The elevated blood UA level could be alleviated by hURAT1 inhibitor benzbromarone treatment in thehURAT1-KI mice whereas no response was observed inWTlittermates. Therefore,hURAT1transgenic mice responded well to inhibitors and can be used to evaluate the therapeutic effects.ConclusionThehURAT1-KI hyperuricaemia mouse model would be valuable for preclinical evaluation of urate-lowering agents toward gout treatment and studying UA metabolic complexities in humans.