Phenylalanine sensitive K562-D cells for the analysis of the biochemical impact of excess amino acid.
Although it is recognized that the abnormal accumulation of amino acid is a cause of the symptoms in metabolic disease such as phenylketonuria (PKU), the relationship between disease severity and serum amino acid levels is not well understood due to the lack of experimental model. Here, we present a novel in vitro cellular model using K562-D cells that proliferate slowly in the presence of excessive amount of phenylalanine within the clinically observed range, but not phenylpyruvate. The increased expression of the L-type amino acid transporter (LAT2) and its adapter protein 4F2 heavy chain appeared to be responsible for the higher sensitivity to phenylalanine in K562-D cells. Supplementation with valine over phenylalanine effectively restored cell proliferation, although other amino acids did not improve K562-D cell proliferation over phenylalanine. Biochemical analysis revealed mammalian target of rapamycin complex (mTORC) as a terminal target of phenylalanine in K562-D cell proliferation, and supplementation of valine restored mTORC1 activity. Our results show that K562-D cell can be a potent tool for the investigation of PKU at the molecular level and to explore new therapeutic approaches to the disease.
1] Department of Pharmacology, Graduate School of Medicine, Chiba University, Chiba [2] Department of Pediatrics, National Hospital Organization, Shimoshizu Hospital, Chiba.
Yoshitami
Y
Sanayama
Department of Pharmacology, Graduate School of Medicine, Chiba University, Chiba.
Akio
A
Matsumoto
Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan.
Naoki
N
Shimojo
Department of Pediatrics, Graduate School of Medicine, Chiba University, Chiba, Japan.
Yoichi
Y
Kohno
Department of Pharmacology, Graduate School of Medicine, Chiba University, Chiba.
Haruaki
H
Nakaya
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D027261:Fusion Regulatory Protein-1 / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006427:Hemin / Q000494:pharmacology; D006801:Humans; D020014:K562 Cells; D000076222:Mechanistic Target of Rapamycin Complex 1; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D010649:Phenylalanine / Q000378:metabolism* / Q000494:pharmacology; D010661:Phenylketonurias / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D010667:Phenylpyruvic Acids / Q000378:metabolism / Q000494:pharmacology; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D014633:Valine / Q000378:metabolism / Q000494:pharmacology
D048868:Adaptor Proteins, Signal Transducing; D027261:Fusion Regulatory Protein-1; C419196:LAT2 protein, human; D046912:Multiprotein Complexes; D010667:Phenylpyruvic Acids; D010649:Phenylalanine; D006427:Hemin; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D014633:Valine; C031606:phenylpyruvic acid