Sensitivity of system A and ASC transport activities to thiol-group-modifying reagents in rat liver plasma-membrane vesicles. Evidence for a direct binding of <i>N</i>-ethylmaleimide and iodoacetamide on A and ASC carriers

Pola, E; Bertran, Joan; Roca, A.; Palacı́n, Manuel; Zorzano, António; Testar, Xavier

doi:10.1042/bj2710297

Cited by 7 publications

(3 citation statements)

References 39 publications

(34 reference statements)

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“…Regulation of Alanine transport in MCF-7 cells treated with Taxol by thiol-group modifying reagents Due to structural differences, different amino acid transport proteins may functionally display differential responses to various chemical modifications such as treatments with thiolgroup modifying reagents. Thiol-modifying reagents such as N-phenylmaleimide (NPM), N-ethylmaleimide (NEM) and iodoacetamide (IA) were reported to have differential effects on different amino acid transport proteins including system B0, ASC and A [13,26]. While the function of both systems ASC and B0 was inhibited similarly by NPM, system B0 is less sensitive to NEM treatment than system ASC [13].…”

Section: Inhibition Of Various Amino Acids On Sodium Dependentmentioning

confidence: 97%

Taxol induced apoptosis regulates amino acid transport in breast cancer cells

Shen

Chen

et al. 2006

Apoptosis

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A major outcome from Taxol treatment is induction of tumor cell apoptosis. However, metabolic responses to Taxol-induced apoptosis are poorly understood. In this study, we hypothesize that alterations in specific amino acid transporters may affect the Taxol-induced apoptosis in breast cancer cells. In this case, the activity of the given transporter may serve as a biomarker that could provide a biological assessment of response to drug treatment. We have examined the mechanisms responsible for Taxol-induced neutral amino acid uptake by breast cancer cells, such as MCF-7, BT474, MDAMB231 and T47D. The biochemical and molecular studies include: (1) growth-inhibition (MTT); (2) transport kinetics: (3) substrate-specific inhibition; (4) effect of thiol-modifying agents NEM and NPM; (5) gene expression of amino acid transporters; and (6) apoptotic assays. Our data show that Taxol treatment of MCF-7 cells induced a transient increase in Na(+)-dependent transport of the neutral amino acid transporter B0 at both gene and protein level. This increase was attenuated by blocking the transporter in the presence of high concentrations of the substrate amino acid. Other neutral amino acid transporters such as ATA2 (System A) and ASC were not altered. Amino acid starvation resulted in the expected up-regulation of System A (ATA2) gene, but not for B0 and ASC. B0 was significantly down regulated. Taxol treatment had no significant effect on the uptake of arginine and glutamate as measured by System y(+) and X(-) (GC) respectively. Tunel assays and FACS cell cycle analysis demonstrated that both Taxol- and doxorubicin-induced upregulation of B0 transporter gene with accompanying increase in cell apoptosis, could be reversed partially by blocking the B0 transporter with high concentration of alanine, and/or by inhibiting the caspase pathway. Both Taxol and doxorubicin treatment caused a significant decrease in S-phase of the cell cycle. However, Taxol-induced an increase primarily in the G2 fraction while doxorubicin caused increase in G1/G0 together with a small increase in G2. In summary, our study showed that Taxol induced apoptosis in several breast cancer cells results in activation of amino acid transporter System B0 at both gene and protein level. Similar response was observed with another chemotherapeutic agent Doxorubicin, suggesting that this increase is in response to apoptosis, and not only due to changes in cell cycle related events.

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Section: Inhibition Of Various Amino Acids On Sodium Dependentmentioning

confidence: 97%

Taxol induced apoptosis regulates amino acid transport in breast cancer cells

Shen

Chen

et al. 2006

Apoptosis

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“…Also, system y ϩ CATs are sensitive to the sulfhydryl reagent N-ethylmaleimide (NEM), which inhibits members of system y ϩ at concentrations nearly tenfold lower than is required to block other proteins (3,15,18). In red blood cells, 200 M NEM blocked system y ϩ transporters, whereas system y ϩ L transporters also present in these cells were not NEM sensitive (19). System y ϩ L transporters move cationic amino acids in an uncoupled manner, as well as neutral amino acids coupled with Na ϩ .…”

mentioning

confidence: 98%

NO control: nitric oxide directly regulates substrate delivery to NOS. Focus on “Nitric oxide can acutely modulate its biosynthesis through a negative feedback mechanism on l-arginine transport in cardiac myocytes”

Gatto

2010

American Journal of Physiology-Cell Physiology

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“…This requires an advance in our knowledge on the structure/function relationship of the A carrier. In this regard, recently published data, which might be useful to develop methods for the quantification of system A, indicate that hepatic system A possesses essential hystidine and cysteine residues (Pola et al, 1990;Bertran et al, 1991) and that it is encoded by mRNA of length 1.9-2.5 kb, as judged by its expression in Xenopus laevis oocytes Tarnuzzer et al, 1990). …”

Section: Introductionmentioning

confidence: 99%

Differential sensitivity of insulin- and adaptive-regulation-induced system A activation to microtubular function in skeletal muscle

Gumà

Castelló

Testar

et al. 1992

Biochemical Journal

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4071. Insulin and adaptive regulation are known to stimulate system A amino acid transport activity in skeletal muscle. The present study was designed to investigate whether activation of system A in muscle is a consequence of processes which rely on microtubule or microfilament function. To that end, extensor digitorum longus (EDL) muscles were incubated in the presence of colchicine and cytochalasin D, well-known inhibitors of microtubule and microfilament activity respectively. 2. Basal a-(methyl)aminoisobutyric acid (MeAIB) uptake decreased after incubation with 5 jtM-colchicine in a time-dependent manner. In keeping with this, adaptive regulation of MeAIB uptake caused by prolonged incubation in the absence of amino acids was substantially decreased in the presence of colchicine. 3. Under these conditions, stimulation of MeAIB uptake by insulin was unaltered in muscle in the presence of colchicine. This contrasted with the insulin-induced stimulation of MeAIB uptake by isolated rat hepatocytes, which was markedly decreased by colchicine. 4. Cytochalasin D, an agent that disrupts microfilaments, did not inhibit basal or insulin-stimulated MeAIB uptake by the incubated muscle. 5. Neither colchicine nor cytochalasin D modified the stimulatory effect of insulin on 3-0-methylglucose uptake by EDL muscle. 6. We conclude that up-regulation of system A by synthesis of new carriers depends on the integrity of microtubular function both in skeletal muscle and in hepatocytes. Microtubules might play a role in the movement of system A-containing vesicles from the Golgi network to the plasma membrane.

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Sensitivity of system A and ASC transport activities to thiol-group-modifying reagents in rat liver plasma-membrane vesicles. Evidence for a direct binding of N-ethylmaleimide and iodoacetamide on A and ASC carriers

Cited by 7 publications

References 39 publications

Taxol induced apoptosis regulates amino acid transport in breast cancer cells

Taxol induced apoptosis regulates amino acid transport in breast cancer cells

NO control: nitric oxide directly regulates substrate delivery to NOS. Focus on “Nitric oxide can acutely modulate its biosynthesis through a negative feedback mechanism on l-arginine transport in cardiac myocytes”

Differential sensitivity of insulin- and adaptive-regulation-induced system A activation to microtubular function in skeletal muscle

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