Metabolism of (13)C5-hydroxyproline in mouse models of Primary Hyperoxaluria and its inhibition by RNAi therapeutics targeting liver glycolate oxidase and hydroxyproline dehydrogenase

Biochim Biophys Acta. 2016 Feb;1862(2):233-9. doi: 10.1016/j.bbadis.2015.12.001. Epub 2015 Dec 2.


Excessive endogenous oxalate synthesis can result in calcium oxalate kidney stone formation and renal failure. Hydroxyproline catabolism in the liver and kidney contributes to endogenous oxalate production in mammals. To quantify this contribution we have infused Wt mice, Agxt KO mice deficient in liver alanine:glyoxylate aminotransferase, and Grhpr KO mice deficient in glyoxylate reductase, with (13)C5-hydroxyproline. The contribution of hydroxyproline metabolism to urinary oxalate excretion in Wt mice was 22±2%, 42±8% in Agxt KO mice, and 36%±9% in Grhpr KO mice. To determine if blocking steps in hydroxyproline and glycolate metabolism would decrease urinary oxalate excretion, mice were injected with siRNA targeting the liver enzymes glycolate oxidase and hydroxyproline dehydrogenase. These siRNAs decreased the expression of both enzymes and reduced urinary oxalate excretion in Agxt KO mice, when compared to mice infused with a luciferase control preparation. These results suggest that siRNA approaches could be useful for decreasing the oxalate burden on the kidney in individuals with Primary Hyperoxaluria.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alcohol Oxidoreductases / genetics*
  • Alcohol Oxidoreductases / metabolism
  • Animals
  • Disease Models, Animal
  • Hydroxyproline / metabolism*
  • Hyperoxaluria, Primary / genetics*
  • Hyperoxaluria, Primary / metabolism
  • Hyperoxaluria, Primary / therapy*
  • Liver / enzymology
  • Liver / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Oxalates / metabolism
  • Proline Oxidase / metabolism*
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / therapeutic use
  • RNAi Therapeutics* / methods


  • Oxalates
  • RNA, Small Interfering
  • Alcohol Oxidoreductases
  • glycollate oxidase
  • Proline Oxidase
  • Hydroxyproline