Cystine and glutamate transport in renal epithelial cells transfected with human system x(-) (c).

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Bridges CC, Zalups RK

Cystine and glutamate transport in renal epithelial cells transfected with human system x(-) (c).

Kidney Int. 2005 Aug;68(2):653-64.

PubMed ID

16014042 [ View in PubMed

]

Abstract

BACKGROUND: System x(-) (c) is a heterodimeric transporter, comprised of a light chain, xCT, and heavy chain, 4F2hc, which mediates the sodium-independent exchange of cystine and glutamate at the plasma membrane. In the current study we tested the hypothesis that stable transfection of Madin-Darby canine kidney (MDCK) cells with human xCT and 4F2hc results in the expression of functional system x(-) (c). METHODS: MDCK cells were transfected stably with human clones for xCT and 4F2hc. Analyses of time- and temperature-dependence, saturation kinetics, and substrate specificity of l-cystine and l-glutamate transport were carried out in control and xCT-4F2hc-transfected MDCK cells. We also measured the uptake of l-cystine in Xenopus oocytes expressing human xCT and/or 4F2hc or xCT and/or rBAT (a heavy chain homologous to 4F2hc). RESULTS: All of the different sets of data revealed that transport of l-cystine and l-glutamate increased significantly (twofold to threefold) in the MDCK cells subsequent to transfection with xCT-4F2hc. Moreover, uptake of l-cystine also increased (about tenfold) in Xenopus oocytes expressing hxCT and h4F2hc. Biochemical analyses of l-cystine uptake in oocytes verified our findings in the transfected MDCK cells. Interestingly, in oocytes injected with rBAT with or without xCT, uptake of l-cystine was significantly greater than that in water-injected oocytes. CONCLUSION: Our findings indicate that stable transfection of MDCK cells with xCT and 4F2hc results in a cell-line expressing a functional system x(-) (c) transporter that can utilize l-cystine and l-glutamate as substrates. This study apparently represents the first stable transfection of a mammalian cell line with system x(-) (c).

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Cystine	Cystine/glutamate transporter	Protein	Humans	Unknown	Not Available	Details