Cystine and glutamate transport in renal epithelial cells transfected with human system x—c

Bridges, Christy C.; Zalups, Rudolfs K.

doi:10.1111/j.1523-1755.2005.00443.x

Cited by 4 publications

(5 citation statements)

References 38 publications

(43 reference statements)

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“…Moreover, there are limited reports available on functional analysis using cancer cell lines, and this is the first study performed using lung cancer cells. The K m value calculated in the present study approximated that reported by Bridges and Zalups (Figure 1b; Bridges & Zalups, 2005). Functional analysis of the cell line is important for evaluation under conditions similar to the intravital environment, and this study could determine the underlying results.…”

Section: Discussionsupporting

confidence: 90%

“…We performed a kinetic analysis for cystine uptake and evaluated the inhibition pattern of sulfasalazine using A549 cells. Although few reports have evaluated the kinetics of xCT (Bridges & Zalups, 2005; Fogal et al., 2007), the evaluation systems and kinetic parameters differ among studies ( K m was calculated as 121.0 μM in xCT‐4F2hc‐transfected cells and 32.47 μM in mixed murine cortical cells containing neurons and astrocytes isolated from mouse brain, respectively), and further accumulation of evidence is crucial. Moreover, there are limited reports available on functional analysis using cancer cell lines, and this is the first study performed using lung cancer cells.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, 4F2 cell‐surface antigen heavy chain (4F2hc), a cofactor encoded by SLC3A2 , is involved in the membrane expression of xCT (Ishii & Mann, 2014). Although there have been some reports on the kinetic analysis of xCT for cystine uptake (Bridges & Zalups, 2005; Fogal et al., 2007), a limited number of studies have been conducted using cell lines, in particular cancer cell lines. As xCT is reportedly involved in the resistance mechanism of some anticancer drugs such as cisplatin, a key drug for lung cancer (Ishimoto et al., 2011), it is crucial to analyze the functions of xCT using a lung cancer cell line.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic analysis of cystine uptake and inhibition pattern of sulfasalazine in A549 cells

Okamoto

Saito

Ueda

et al. 2021

Biopharm & Drug Disp

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Cystine/glutamate transporter (xCT) is an antiporter involved in cystine uptake and glutamate efflux. However, there are very few reports regarding the kinetic analysis of xCT for cystine uptake using cancer cell lines, as well as the inhibition pattern of sulfasalazine, an inhibitor of xCT, for cystine uptake. Therefore, the purpose of this study was to clarify the kinetics of xCT in A549 cells, human lung cancer cells, and to reveal the inhibition pattern of sulfasalazine. Cystine uptake occurred in a time‐dependent manner, with linear cystine uptake observed for 5 min. Additionally, sulfasalazine inhibited cystine uptake in a concentration‐dependent manner, presenting an IC50 value of 24.7 ± 5.6 μM. Cystine uptake was saturated with increasing concentration, demonstrating Km and Vmax values of 179.4 ± 26.7 μM and 30.4 ± 2.3 nmol/min/mg protein, respectively. Moreover, during cystine uptake with sulfasalazine, Km and Vmax were >300 μM and 8.0 ± 1.5 nmol/min/mg protein, respectively, suggesting that sulfasalazine might demonstrate a mixed inhibition pattern. Furthermore, xCT siRNA decreased the xCT mRNA level and reduced cystine uptake. In conclusion, xCT was involved in the cystine uptake in A549 cells and sulfasalazine showed a mixed inhibition pattern to xCT.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Kinetic analysis of cystine uptake and inhibition pattern of sulfasalazine in A549 cells

Okamoto

Saito

Ueda

et al. 2021

Biopharm & Drug Disp

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“…All experiments were carried out in both water-and ATB 0,ϩ -injected oocytes in a manner similar to that described previously (Bridges and Zalups, 2005b). In brief, 3 days following injection, the oocytes were separated into groups of five in 24-well plates and were washed with 1 ml of room temperature (25°C) uptake buffer (25 mM HEPES/Tris, 140 mM NaCl, 5.4 mM KCl, 1.8 mM CaCl 2 , 0.8 mM MgSO 4 , and 5 mM glucose, pH 7.5).…”

Section: Methodsmentioning

confidence: 99%

System B^0,+and the Transport of Thiol-S-Conjugates of Methylmercury

Bridges¹,

Zalups²

2006

J Pharmacol Exp Ther

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Methylmercury (CH 3 Hgϩ ) is a clinically relevant toxicant that is the most abundant form of mercury found in the environment. After exposure, it accumulates in the kidneys, liver, and central nervous system. The mechanisms by which this toxicant is taken up by target cells are only now beginning to be understood. Some experimental data support a hypothesis involving molecular mimicry, whereby thiol conjugates of methylmercury (especially a cysteine S-conjugate) mimic one or more amino acids and are transported into target cells by amino acid transporters. In the present study, we tested the hypothesis that Cys and homocysteine (Hcy) S-conjugates of methylmercury (CH 3 Hg-S-Cys and CH 3 Hg-S-Hcy, respectively) mimic one or more amino acids at the site of the Na ϩ -dependent amino acid transporter, system B 0,ϩ . In the kidneys, system B 0,ϩ is situated on the luminal plasma membrane of proximal tubular epithelial cells. To test our hypothesis, we measured uptake of CH 3 Hg-S-Cys and CH 3 Hg-S-Hcy in Xenopus laevis oocytes injected with water or capped RNA encoding mouse ATB 0,ϩ . Analyses of time course, substrate specificity, and saturation kinetics showed that the uptake of CH 3 Hg-S-Cys and CH 3 Hg-S-Hcy was 5-to 10-fold greater in oocytes expressing ATB 0,ϩ than in corresponding water-injected controls. Moreover, the transport of CH 3 Hg-S-Cys and CH 3 Hg-S-Hcy was inhibited by substrates transported by system B 0,ϩ . Finally, our data indicate that CH 3 Hg-S-Cys and CH 3 Hg-S-Hcy may mimic of one or more amino acids (e.g., methionine) that are normally transported by system B 0,ϩ . To our knowledge, this is the first report implicating system B 0,ϩ in the transport of any mercuric species.

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“…Some of these mercuric conjugates serve as transportable substrates of certain carrier proteins in target organs such as the kidneys, liver, and brain 7 . Because the chemical structures of CH 3 Hg-S-Cys and the Hcy S-conjugate of CH 3 Hg + (CH 3 Hg-S-Hcy) are similar to that of the amino acid methionine, it has been postulated that these two conjugates may act as mimics of methionine to gain access to certain compartments of the body [8][9] . Indeed, several studies have provided indirect evidence for the involvement of molecular mimicry in the transport of CH 3 Hg-S-Cys [10][11][12][13] .…”

Section: Introductionmentioning

confidence: 99%

Transport of Methylmercury through the Epithelial Type Amino Acid Transporter System B0

Islam

Anzai

Ahmed

et al. 2019

J. Natl Inst. Neurosci Bangladesh

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Background: System B0 is a sodium dependent transporter that transports wide variety of neutral amino acids in the intestinal and renal proximal tubular epithelial cells. Methylmercury (MeHg) readily and non-enzymatically reacts with cysteine to form conjugate structurally similar to the amino acid methionine. Objective: In this study, we investigated the molecular mechanism of absorptive transport of MeHg in intestine using Xenopus oocytes expressing hB0AT1 and the uptake of metylmercry-Cys (MeHg-Cys) by heterodimeric amino acids transporter. Methodology: We confirmed the uptake of [14C] L-Leucine a potent substrate for the hB0AT1 amino acids transporter. The uptake of [14C] L-leucine by hB0AT1 was inhibited by MeHg-Cys conjugate, leucine, cysteine, methinine and phenylalanine in concentration–dependent manner. The IC50 of MeHg-Cys conjugate was significantly lower than that of leucine, cysteine, methinine and phenylalanine, indicating that hB0AT1 is a high affinity MeHg transporter. To assess MeHg-Cys conjugate transport, we measured [14C] MeHg uptake in Xenopus oocytes expressing hB0AT1 in presence or absence of sodium. The [14C] MeHg was transport only in the presence of cysteine and the transport was significantly sodium dependent and inhibited by a system B0 inhibitor 2-aminobicyclo-[2,21]- haptane-2-carboxylic acid (BCH). Result: The current findings indicate that hB0AT1 and heterodimeric amino acids absorb MeHg in the form of cysteine conjugate from the intestinal lumen across the brush-border membrane in to the cells and is supposed to be plays a critical role in the pathogenesis of Minamata disease and present results descried a major molecular mechanism by which MeHg is transported across cell membranes and indicate that metal complexes may form a novel class of substrates for amino acid carriers. Conclusion: In this experiment the results also suggest that uptake of Methionine and MeHg-Cys by heterodimeric amino acid transporter is significantly correlated where the uptake of Methionine and MeHg-Cys between heterodimeric amino acid transporter and hB0AT1 is not correlated. Journal of National Institute of Neurosciences Bangladesh, 2019;5(2): 127-136

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Cystine and glutamate transport in renal epithelial cells transfected with human system x—c

Cited by 4 publications

References 38 publications

Kinetic analysis of cystine uptake and inhibition pattern of sulfasalazine in A549 cells

Kinetic analysis of cystine uptake and inhibition pattern of sulfasalazine in A549 cells

System B^0,+and the Transport of Thiol-S-Conjugates of Methylmercury

Transport of Methylmercury through the Epithelial Type Amino Acid Transporter System B0

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Cystine and glutamate transport in renal epithelial cells transfected with human system x—c

Cited by 4 publications

References 38 publications

Kinetic analysis of cystine uptake and inhibition pattern of sulfasalazine in A549 cells

Kinetic analysis of cystine uptake and inhibition pattern of sulfasalazine in A549 cells

System B0,+and the Transport of Thiol-S-Conjugates of Methylmercury

Transport of Methylmercury through the Epithelial Type Amino Acid Transporter System B0

Contact Info

Product

Resources

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System B^0,+and the Transport of Thiol-S-Conjugates of Methylmercury