| Augmentation of reduced folate carrier-mediated folate/antifolate transport through an antiport mechanism with 5-aminoimidazole-4-carboxamide riboside monophosphate. | |
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MedLine Citation:
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PMID: 22554803 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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5-Aminoimidazole-4-carboxamide riboside (AICAR), an agent with diverse pharmacological properties, augments transport of folates and antifolates. This report further characterizes this phenomenon and defines the mechanism by which it occurs. Exposure of HeLa cells to AICAR resulted in augmentation of methotrexate, 5-formyltetrahydrofolate, and 5-methyltetrahydrofolate initial rates and net uptake in cells that express the reduced folate carrier (RFC). This did not occur in cells that express only the proton-coupled folate transporter and accumulated folates by this mechanism. Transport stimulation correlated with the accumulation of 5-aminoimidazole-4-carboxamide ribotide monophosphate (ZMP), the monophosphate derivative of AICAR, within cells as established by liquid chromatography. When ZMP formation was blocked with 5-iodotubercidin, an inhibitor of adenosine kinase, folate transport stimulation by AICAR was absent. When cells first accumulated ZMP and were then exposed to 5-iodotubercidin or AICAR-free buffer, the ZMP level markedly decreased and folate transport stimulation was abolished. Extracellular ZMP inhibited RFC-mediated folate influx, and the presence of intracellular ZMP correlated with inhibition of folate efflux. The data indicate that intracellular ZMP trans-stimulates folate influx and inhibits folate efflux, which, together, produce a marked augmentation in the net cellular folate level. This interaction among ZMP, folates, and RFC, a folate/organic phosphate antiporter, is consistent with a classic exchange reaction. The transmembrane gradient for one transport substrate (ZMP) drives the uphill transport of another (folate) via a carrier used by both substrates, a phenomenon intrinsic to the energetics of RFC-mediated folate transport. |
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Authors:
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Michele Visentin; Rongbao Zhao; I David Goldman |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural Date: 2012-05-03 |
Journal Detail:
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Title: Molecular pharmacology Volume: 82 ISSN: 1521-0111 ISO Abbreviation: Mol. Pharmacol. Publication Date: 2012 Aug |
Date Detail:
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Created Date: 2012-07-17 Completed Date: 2012-10-09 Revised Date: 2013-04-16 |
Medline Journal Info:
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Nlm Unique ID: 0035623 Medline TA: Mol Pharmacol Country: United States |
Other Details:
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Languages: eng Pagination: 209-16 Citation Subset: IM |
Affiliation:
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Albert Einstein Cancer Center, 1300 Morris Park Ave., Bronx, NY 10461, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Aminoimidazole Carboxamide
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analogs & derivatives*,
metabolism,
pharmacology Drug Synergism Folic Acid Antagonists / agonists*, metabolism* HeLa Cells Humans Protein Transport / drug effects, physiology Reduced Folate Carrier Protein / agonists*, metabolism* Ribonucleotides / metabolism*, pharmacology* |
| Grant Support | |
ID/Acronym/Agency:
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CA82621/CA/NCI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Folic Acid Antagonists; 0/Reduced Folate Carrier Protein; 0/Ribonucleotides; 0/SLC19A1 protein, human; 360-97-4/Aminoimidazole Carboxamide; F0X88YW0YK/AICA ribonucleotide |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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