B0ATI (Slc6a19) is a sodium dependent neutral amino acid transporter catalyzing the secondary active transport of neutral amino acids across the brush border membrane of kidney and intestine. The surface expression of B0ATI requires either collectrin or angiotensin converting enzyme 2 (ACE2) in the kidney and intestine, respectively. A Slc6a19 KO mouse showed neutral aminoaciduria in urine as observed in Hartnup disorder, a benign medical condition which is caused by mutations in the Slc6a19 gene. Further characterization of these mice revealed that lack of B0ATI improves glucose tolerance and enhances fat metabolism. This would suggest that pharmacological inhibition of B0ATI using chemical compounds could lead to new drugs to treat type 2 diabetes (T2DM).
An initial screen of 20,000 compounds was carried out using a high throughput screening (HTS) assay based on membrane depolarization. This generated a group of 64 inhibitory compounds. Based on the strongest inhibition of B0ATI-mediated transport, 33 compounds were selected for further characterization. Radio-labelled amino acid uptake assays were used to determine the potency (IC50) and mechanism (competitive or non-competitive) of inhibition, as well as the specificity of B0AT1 inhibitors.
Five novel B0AT1 inhibitors with IC50 values below 10μM were identified from the HTS of a small molecule compound library. These compounds will be further tested using in-vivo pharmacological studies.