The effects of the inactivation of Hydroxyproline dehydrogenase on urinary oxalate and glycolate excretion in mouse models of primary hyperoxaluria

• Published in: Biochimica et biophysica acta. Molecular basis of disease Vol. 1866; no. 3; p. 165633
• Main Authors: Buchalski, Brianna, Wood, Kyle D., Challa, Anil, Fargue, Sonia, Holmes, Ross P., Lowther, W. Todd, Knight, John
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.03.2020
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Calcium - metabolism; Disease Models, Animal; Female; Glycolate; Glycolates - metabolism; Glycolates - urine; Humans; Hydroxyproline - metabolism; Hyperoxaluria, Primary - metabolism; Kidney - metabolism; Kidney stone; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Mouse models; Oxalate; Oxalates - metabolism; Oxalates - urine; Oxidoreductases - metabolism; Primary hyperoxaluria; Proline Oxidase - metabolism; Primary hyperoxaluria; Hydroxyproline metabolism; Glycolate; Oxalate; Mouse models; Kidney stone
• DOI: 10.1016/j.bbadis.2019.165633
• ISSN: 0925-4439

The major clinical manifestation of the Primary Hyperoxalurias (PH) is increased production of oxalate, as a consequence of genetic mutations that lead to aberrant glyoxylate and hydroxyproline metabolism. Hyperoxaluria can lead to the formation of calcium-oxalate kidney stones, nephrocalcinosis and renal failure. Current therapeutic approaches rely on organ transplants and more recently modifying the pathway of oxalate synthesis using siRNA therapy. We have recently reported that the metabolism of trans-4-hydroxy-L-proline (Hyp), an amino acid derived predominantly from collagen metabolism, is a significant source of oxalate production in individuals with PH2 and PH3. Thus, the first enzyme in the Hyp degradation pathway, hydroxyproline dehydrogenase (HYPDH), represents a promising therapeutic target for reducing endogenous oxalate production in these individuals. This is supported by the observation that individuals with inherited mutations in HYPDH (PRODH2 gene) have no pathological consequences. The creation of mouse models that do not express HYPDH will facilitate research evaluating HYPDH as a target. We describe the phenotype of the Prodh2 knock out mouse model and show that the lack of HYPDH in PH mouse models results in lower levels of urinary oxalate excretion, consistent with our previous metabolic tracer and siRNA-based knockdown studies. The double knockout mouse, Grhpr KO (PH2 model) and Prodh2 KO, prevented calcium-oxalate crystal deposition in the kidney, when placed on a 1% Hyp diet. These observations support the use of the Grhpr KO mice to screen HYPDH inhibitors in vivo. Altogether these data support HYPDH as an attractive therapeutic target for PH2 and PH3 patients. [Display omitted] •Hydroxproline metabolism contributes to oxalate production.•Hydroxyproline dehydrogenase (HYPDH) is a target for treating primary hyperoxaluria.•Deletion of HYPDH in mice increases hydroxyproline in urine and plasma.•Urine oxalate and glycolate levels can be lowered by deletion of HYPDH.•Loss of HYPDH can protect GRHPR KO mice from calcium oxalate crystal formation.