A mouse model for cystinuria type I

Area of Science:

• Genetics and Molecular Biology
• Nephrology and Urology
• Inborn Errors of Metabolism

Background:

• Cystinuria is a common inherited metabolic disorder affecting 1-2% of renal lithiasis cases.
• It results from defects in the rBAT/b0,+AT transporter, impairing renal and intestinal reabsorption of cystine and basic amino acids.
• Current understanding of cystinuria pathophysiology and treatment evaluation is limited by the lack of suitable animal models.

Purpose of the Study:

• To identify and characterize a novel mouse model for cystinuria.
• To investigate the genetic basis of the identified mutation.
• To evaluate the utility of this mouse model for studying cystinuria and testing therapeutic strategies.

Main Methods:

• An N-ethyl-N-nitrosourea mutagenesis screen was employed to identify recessive mutations.
• Phenotypic analysis included urine amino acid profiling and assessment of urolithiasis.
• Positional cloning was used to identify the causative gene and specific mutation.

Main Results:

• A mutant mouse exhibiting elevated urinary lysine, arginine, and ornithine was identified.
• The mouse displayed clinical signs of urolithiasis and complications.
• A missense mutation (D140G) in the solute carrier family 3 member 1 gene (Slc3a1) was identified as the causative mutation in the rBAT protein.

Conclusions:

• The identified Slc3a1 mutation results in a mouse model that faithfully mimics human cystinuria type I.
• This novel mouse model is valuable for elucidating cystinuria pathophysiology.
• The model provides a platform for evaluating potential therapeutic and metaphylactic interventions for cystinuria.