Publication Date:
2014-06-16
Description:
The kidney is one of the major loci for the expression of cystathionine β-synthase (CBS) and cystathionine -lyase (CTH). While CBS-deficient ( Cbs –/– ) mice display homocysteinemia/methioninemia and severe growth retardation, and rarely survive beyond the first 4 wk, CTH-deficient ( Cth –/– ) mice show homocysteinemia/cystathioninemia but develop with no apparent abnormality. This study examined renal amino acid reabsorption in those mice. Although both 2-wk-old Cbs –/– and Cth –/– mice had normal renal architecture, their serum/urinary amino acid profiles largely differed from wild-type mice. The most striking feature was marked accumulation of Met and cystathionine in serum/urine/kidney samples of Cbs –/– and Cth –/– mice, respectively. Levels of some neutral amino acids (Val, Leu, Ile, and Tyr) that were not elevated in Cbs –/– serum were highly elevated in Cbs –/– urine, and urinary excretion of other neutral amino acids (except Met) was much higher than expected from their serum levels, demonstrating neutral aminoaciduria in Cbs –/– (not Cth –/– ) mice. Because the bulk of neutral amino acids is absorbed via a B 0 AT1 transporter and Met has the highest substrate affinity for B 0 AT1 than other neutral amino acids, hypermethioninemia may cause hyperexcretion of neutral amino acids.
Print ISSN:
1931-857X
Electronic ISSN:
1522-1466
Topics:
Medicine
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