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Updated: Jan 15, 2026
High-throughput Screening for Small-molecule Modulators of Inward Rectifier Potassium Channels
Published on: January 27, 2013
Screening for novel L-type amino acid transporter 1 (SLC7A5) inhibitors using a fluorescent amino acid
Toru Kimura1, Toru Tanaka2, Hiroyuki Sakurai3
1Faculty of Pharmacy and Pharmaceutical Sciences, Department of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama, 350-0295, Japan; Department of Pharmacology and Toxicology, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo, 181-8611, Japan.
Abstract:
L-type amino acid transporter 1 (LAT1) facilitates the transport of neutral amino acids with bulky side chains, including many essential amino acids that activate the mechanistic target of rapamycin (mTOR), thereby promoting cell proliferation. Inhibition of LAT1 suppresses abnormal cell growth, such as in cancer and polycystic kidney disease. Fluorescent probes are essential tools for monitoring transport activity and screening for novel inhibitors. We discovered that the fluorescent amino acid (S)-2-Amino-3-(9-oxo-9,10-dihydroacridin-2-yl) propanoic acid hydrochloride (H-Ala (2-Acd)-OH・HCl) is specifically transported by LAT1 in Ca9-22 cells and is effective for drug screening. The transport of H-Ala (2-Acd)-OH・HCl was inhibited by the LAT1-specific inhibitor JPH203 and by excess leucine, a natural LAT1 substrate. In contrast, the structurally similar fluorescent amino acid (S)-2-Amino-3-(12-oxo-5,12-dihydrobenzo [b] acridin-2-yl) propanoic acid hydrochloride (H-Ala (2-Bacd)-OH・HCl) exhibited minimal cellular uptake. Using H-Ala (2-Acd)-OH・HCl and Ca9-22 cells, we screened over 10,000 compounds and identified several potent LAT1 inhibitors.
Insights
Researchers developed a new fluorescent probe, H-Ala (2-Acd)-OH・HCl, specifically for L-type amino acid transporter 1 (LAT1). This probe enables efficient screening of compounds to discover novel LAT1 inhibitors for cancer and other diseases.
Area of Science:
- Biochemistry
- Cell Biology
- Pharmacology
Background:
- L-type amino acid transporter 1 (LAT1) is crucial for transporting essential amino acids that fuel cell proliferation.
- LAT1 dysregulation is implicated in diseases like cancer and polycystic kidney disease.
- Developing specific fluorescent probes is vital for studying LAT1 activity and identifying inhibitors.
Purpose of the Study:
- To discover and validate a novel fluorescent amino acid probe for LAT1.
- To utilize this probe for high-throughput screening of potential LAT1 inhibitors.
- To advance the development of therapeutics targeting LAT1-associated diseases.
Main Methods:
- Synthesis and characterization of fluorescent amino acid derivatives, H-Ala (2-Acd)-OH・HCl and H-Ala (2-Bacd)-OH・HCl.
- Assessment of cellular uptake and LAT1 specificity in Ca9-22 cells.
- Inhibition assays using a known LAT1 inhibitor (JPH203) and a natural substrate (leucine).
- High-throughput screening of a compound library (>10,000 compounds) using the developed probe.
Main Results:
- H-Ala (2-Acd)-OH・HCl was specifically transported by LAT1 in Ca9-22 cells.
- Transport of H-Ala (2-Acd)-OH・HCl was inhibited by JPH203 and leucine, confirming LAT1 specificity.
- The structurally similar H-Ala (2-Bacd)-OH・HCl showed minimal cellular uptake.
- Screening identified several potent LAT1 inhibitors using H-Ala (2-Acd)-OH・HCl.
Conclusions:
- H-Ala (2-Acd)-OH・HCl is a novel and effective fluorescent probe for LAT1.
- This probe facilitates the discovery of new LAT1 inhibitors.
- The findings offer a valuable tool for cancer research and drug development targeting LAT1.
