title: Structure-activity relations of leucine derivatives reveal critical moieties for cellular uptake and activation of mTORC1-mediated signaling.
abstract: Among amino acids, leucine is a potential signaling molecule to regulate cell growth and metabolism by activating mechanistic target of rapamycin complex 1 (mTORC1). To reveal the critical structures of leucine molecule to activate mTORC1, we examined the structure-activity relationships of leucine derivatives in HeLa S3 cells for cellular uptake and for the induction of phosphorylation of p70 ribosomal S6 kinase 1 (p70S6K), a downstream effector of mTORC1. The activation of mTORC1 by leucine and its derivatives was the consequence of two successive events: the cellular uptake by L-type amino acid transporter 1 (LAT1) responsible for leucine uptake in HeLa S3 cells and the activation of mTORC1 following the transport. The structural requirement for the recognition by LAT1 was to have carbonyl oxygen, alkoxy oxygen of carboxyl group, amino group and hydrophobic side chain. In contrast, the requirement for mTORC1 activation was more rigorous. It additionally required fixed distance between carbonyl oxygen and alkoxy oxygen of carboxyl group, and amino group positioned at α-carbon. L-Configuration in chirality and appropriate length of side chain with a terminal isopropyl group were also important. This confirmed that LAT1 itself is not a leucine sensor. Some specialized leucine sensing mechanism with rigorous requirement for agonistic structures should exist inside the cells because leucine derivatives not transported by LAT1 did not activate mTORC1. Because LAT1-mTOR axis is involved in the regulation of cell growth and cancer progression, the results from this study may provide a new insight into therapeutics targeting both LAT1 and leucine sensor.
authors.affiliation: Department of Bio-System Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors.forename: Shushi
authors.initials: S
authors.lastname: Nagamori
authors.affiliation: Department of Bio-System Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors.forename: Pattama
authors.initials: P
authors.lastname: Wiriyasermkul
authors.affiliation: Department of Bio-System Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors.forename: Suguru
authors.initials: S
authors.lastname: Okuda
authors.affiliation: Department of Pharmaceutical Manufacturing Chemistry, Kyoto Pharmaceutical University, Kyoto, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Kojima
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Hari
authors.affiliation: Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan.|Department of Technology and Ecology, Hall of Global Environmental Studies, Kyoto University, Kyoto, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kiyonaka
authors.affiliation: Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan.|Department of Technology and Ecology, Hall of Global Environmental Studies, Kyoto University, Kyoto, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Mori
authors.affiliation: Advanced Clinical Research Center, Fukushima Medical University, Fukushima, Japan.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Tominaga
authors.affiliation: Department of Bio-System Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Ohgaki
authors.affiliation: Department of Bio-System Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan. ykanai@pharma1.med.osaka-u.ac.jp.
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Kanai
mesh_terms: D001692:Biological Transport; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D027283:Large Neutral Amino Acid-Transporter 1 / Q000235:genetics / Q000378:metabolism*; D007930:Leucine / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D027283:Large Neutral Amino Acid-Transporter 1; D046912:Multiprotein Complexes; C546842:MTOR protein, human; D000076222:Mechanistic Target of Rapamycin Complex 1; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D007930:Leucine
keywords: Amino acid signaling; Amino acid transporter; LAT1; Leucine; Structure–activity relationship; mTOR