Altered sensitivity of system A amino acid transport to ouabain in normal and transformed C3H-10T1/2 cells during the cell cycle.

Leister, Kirk J.; Schenerman, Mark A.; Racker, Efraim

doi:10.1073/pnas.86.3.783

Cited by 8 publications

(3 citation statements)

References 21 publications

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“…Both carriers, the A system and the Na',K+-ATPase, are thus related mechanistically by sharing Na' as a substrate. It is therefore not surprising that the activities of both these systems are closely interrelated (16)(17)(18)(19)(20)(21)(22). Besides the concentration of Na' affecting the activity of the Na',K+-ATPase, under certain conditions that lead to increases in Na+ content there is an associated increase in the number of Na+,K+-ATPase molecules on the plasma membrane (16,(23)(24)(25)(26)(27)(28)(29)(30) and an increase in the abundance of their corresponding mRNA (29,30).…”

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confidence: 99%

Evidence for coordinate regulation of the A system for amino acid transport and the mRNA for the alpha 1 subunit of the Na+,K(+)-ATPase gene in Chinese hamster ovary cells.

Qian

Pastor‐Anglada

Englesberg

1991

Proc. Natl. Acad. Sci. U.S.A.

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Previous work suggested that the structural gene for the A system transporter and the mRNA for the a subunit of the Na+,K+-ATPase in Chinese hamster ovary cells CHO-K1 [wild type (WT)] are coordinately controlled by regulatory gene R1. This conclusion was based on analysis of a mutant for the A system, alar4. This mutant had a constitutive level of A system transport activity equal to the level found in derepressed WT cells and a 4 times increase in abundance ofthe a, subunit of Na',K'-ATPase mRNA over that found in repressed WT. The level of Na+ per cell in alar4 was not significantly greater than that found in the WT. To further characterize the likely coregulation of both genes, we have studied the A system activity and Na+,K+-ATPase mRNA a,-subunit levels in cells grown under various conditions that result in repression or derepression of the A system in the WT. System A activity increased up to 2-3 times the basal transport rate (repressed state) and Na+,K+-ATPase mRNA a,-subunit levels showed a 3-fold increase after amino acid starvation (derepressed state). These changes occurred along with a decrease in intracellular Na+ levels. N-Methyl-a-aminoisobutyric acid and fi-alanine, previously shown to be corepressors for the A system, prevented to a similar extent A system derepression and Na+,K+-ATPase mRNA a,-subunit accumulation. On the other hand, phenylalanine and lysine, amino acids that are not corepressors of the A system, failed to significantly prevent derepression of both genes. Hybrids between the WT and ala'4 have the phenotype of the WT when grown under repressed conditions. These results give further support to the proposition that both the A system transporter and mRNA for the aI subunit of the Na+,K+-ATPase are coordinately controlled by regulatory gene R1 and elevated Na+ concentrations are not involved. No Na+,K+-ATPase activity was detected in derepressed cells. Activity was restored by the addition of monensin. However, this activity was no greater than that obtained in repressed cells. Indications are that the reduced Na+ content in derepressed cells inhibits Na+,K+-ATPase activity and that conditions that favored derepression do not allow for de novo synthesis of the Na+,K+-ATPase.Evidence has been presented suggesting that the activity of the A system of amino acid transport and the Na+,K+-ATPase is coordinately regulated at the transcriptional level by means of repression and negative control by the A system regulatory gene R1 (1).The A system and the Na+ ,K+-ATPase are ubiquitous integral membrane proteins in mammalian cells that function as secondary and primary active transporters, respectively. The A system accepts as substrates most neutral amino acids but shows a strong preference for proline and small straight-chain amino acids such as alanine (2). It is Na' dependent and transports one Na' into the cells with each amino acid (3). This system is inducible by hormones (4-6), repressible by amino acids, which it generally transports (7-11), and present with increased activ...

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confidence: 99%

Evidence for coordinate regulation of the A system for amino acid transport and the mRNA for the alpha 1 subunit of the Na+,K(+)-ATPase gene in Chinese hamster ovary cells.

Qian

Pastor‐Anglada

Englesberg

1991

Proc. Natl. Acad. Sci. U.S.A.

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“…Changes in membrane transporter activity are frequently observed when cells are stimulated with serum or purified growth factors and may be associated with cell-cycle-specific events. In mouse fibroblasts system A amino acid transport changes with the cell cycle, with a peak near the end of GI just prior to entering S phase (Leister et al, 1989). Insulin increases glucose transport in muscle tissue and has effects on Ca2+ and amino acid fluxes in muscle and other tissues (Klip et al, 1984;Tupper and Smith, 1985;Bettger and McKeehan, 19861, and CSF-1 stimulates coupling between hexose transport and hexokinase activity in rat and murine peritoneal macrophages (Rist et al, 1990).…”

Section: Discussionmentioning

confidence: 99%

CSF‐1 stimulates nucleoside transport in S1 macrophages

Meckling‐Gill¹,

Guilbert

Cass³

1993

Journal Cellular Physiology

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We have examined nucleoside transport (NT) in a cell line derived from primary day 7 murine bone marrow macrophages (S1 macrophages) in response to the macrophage growth factor, colony-stimulating factor 1 (CSF-1). Adenosine and uridine transport in quiescent S1 macrophages occurred primarily by two facilitated diffusional routes, one that was sensitive and one that was relatively resistant to the inhibitor nitrobenzylthioinosine (NBMPR). Addition of CSF-1 to quiescent cultures resulted in increased adenosine and uridine transport with biphasic kinetics with respect to the cell cycle. Basal NT activity was elevated (about twofold) within 15 min of CSF-1 addition, returned to near basal levels by 1 h, and then increased again (three- to fourfold) 8-12 h later, returning again to basal levels by 48 h post CSF-1 stimulation. We propose that the large increase in NT activity at 8-12 h corresponded with the time when cultures synchronously began to enter the S phase of the cell cycle. In addition to these changes in the absolute rates, the proportions of NBMPR-sensitive and NBMPR-insensitive transport also change after CSF-1 addition. Quiescent cultures exhibited primarily NBMPR-insensitive transport while logrithmically growing cultures exhibited primarily NBMPR-sensitive nucleoside transport activity. The increase in the NBMPR-sensitive component of the transport process paralleled a similar increase in the number of high-affinity NBMPR binding sites, suggesting that the mechanism for upregulating NBMPR-sensitive NT activity involves increases in the number of NBMPR-sensitive transporter sites. Interestingly, we were unable to detect Na(+)-dependent concentrative uptake of adenosine, uridine, or formycin-B either in the S1 macrophage cell line or in primary (day 7) murine macrophages. Thus these bone marrow derived macrophages did not display the characteristically large Na(+)-dependent transport systems observed by others in peritoneal macrophages, implying that these two populations of macrophages are, indeed, functionally distinct.

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“…In cultured cells, metabolism is varying with cell density, and cells in late passages may show profound alterations in morphology as well as in metabolic activity when compared with early culture stages (Green & Goldberg 1964;Kolodny & Gross 1969;Leister et al 1989). Due to these observations, the experiment was performed on nonconfluent cultures with mitotic activity as well as on one-week-old confluent cultures, and an early and similar passage number was selected for all the cultures.…”

Section: Discussionmentioning

confidence: 99%

Amino acid incorporation in cell cultures from eyes with pseudo‐exfoliation material

Nicolaissen

Ringvold

Næss

1992

Acta Ophthalmologica

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Conjunctival tissue was removed from eyes with and without pseudo-exfoliation material during cataract surgery. Cells derived from these samples were maintained in vitro. Confluent cultures were examined by transmission electron microscopy, and non-confluent as well as confluent cultures were examined for their ability to incorporate 3H-leucine and 3H-proline into TCA-precipitated material. Cells derived from both types of samples showed deposition of extracellular matrix, and a similar incorporation of the two amino acids. It is concluded that in vitro studies allow examination of basic metabolic patterns under varying conditions, and also a search for possible differences in such functions between tissues with and without production of pseudo-exfoliation material.

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Altered sensitivity of system A amino acid transport to ouabain in normal and transformed C3H-10T1/2 cells during the cell cycle.

Abstract: Quiescent C3H-lOT1/2 mouse fibroblasts that have not undergone any type of stress have a relatively low rate of 2-aminoisobutyrate (Aib) uptake by means of system A,

Cited by 8 publications

References 21 publications

Evidence for coordinate regulation of the A system for amino acid transport and the mRNA for the alpha 1 subunit of the Na+,K(+)-ATPase gene in Chinese hamster ovary cells.

Evidence for coordinate regulation of the A system for amino acid transport and the mRNA for the alpha 1 subunit of the Na+,K(+)-ATPase gene in Chinese hamster ovary cells.

CSF‐1 stimulates nucleoside transport in S1 macrophages

Amino acid incorporation in cell cultures from eyes with pseudo‐exfoliation material

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