RNAi Mediated Knock Down of Prolyl Hydroxylase II in Liver Tissue Enhances Lactate Clearance in Mice

Abstract

Patients with respiratory chain disorders can present with lactic acidosis (Jain et al., 2016). At present, mitochondrial diseases caused by mutant mtDNAs remain largely untreatable (Ogasawara, Nakada, & Hayashi, 2010). A proposed mechanism for reducing lactic acidosis in these patients is to target the expression of HIF prolyl hydroxylases (PHDs). In the presence of oxygen, hypoxia inducible factor α (HIFα) becomes prolyl hydroxylated by PHDs (Epstein et al., 2001), which results in ubiquitination and proteasomal degradation. However, under hypoxic conditions, where oxygen is not readily available, PHD activity is decreased. The result is HIFα stabilization and translocation to the nucleus, upon which HIFα activates multiple genes that promote glycolysis over oxidative metabolism (Balligand, Feron, & Dessy, 2009). In the human genome, PHD2 is encoded by Egln1. Here we designed an siRNAs that lead to the depletion of PHD2, by reducing Egln1 expression. Egln1 expression was reduced in vitro and in vivo. On day 7 and day 14 after a single dose of 20 mg/kg with an siRNA targeting Egln1 in c57/BL6 mice demonstrated enhanced lactate clearance when submitted to a lactate challenge, demonstrating the potential of PHD2 reduction via siRNA-mediated knockdown to clear excess lactate production associated with mitochondrial disease.