Glutaminase 2 Knockdown Reduces Hyperammonemia and Associated Lethality of Urea Cycle Disorder Mouse Model

Urea cycle disorders with hyperammonemia remain difficult to treat and eventually necessitate liver transplantation. An ornithine transcarbamylase defect (Otcspf-ash) mouse model, a model of urea cycle disorder, was used to test whether knockdown of a key glutamine metabolism enzyme glutaminase 2 (Gls2) or glutamine dehydrogenase 1 (Glud1) could rescue the hyperammonemia and associated lethality induced by a high protein diet. Reduced hepatic expression of Gls2, but not Glud1, by AAV8-mediated delivery of a short hairpin RNA in Otcspf-ash mice diminished hyperammonemia, reduced body weight loss, and reduced lethality. These data suggest that Gls2 hepatic knockdown could help alleviate risk for hyperammonemia and other clinical manifestations of patients suffering from defects in the urea cycle. Wildtype (B6EiC3SnF1/J, The Jackson Laboratory Stock No. 001875, abbr: WT) and Otcspf-ash (B6EiC3Sn a/A-Otcspf-ash/J, The Jackson Laboratory Stock No. 001811, abbr: OTC) mice at 4 months old were randomized into 3 groups of shRNA-scramble (abbr: control), shRNA-Gls2 (abbr: sh-Gls2) and shRNA-Glud1 (abbr: sh-Glud1) (n=12-13 for each group). IV injection delivery of AAV were applied at week 0. Mice were switched from chow diet to 40% high protein diet at week 2 until the end of the study at week 5. Liver samples were collected at week 5 for RNA sequencing.