Linked Life Data

9689927

Source:http://linkedlifedata.com/resource/pubmed/id/9689927

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1998-8-14
pubmed:abstractText
A variant of the L1210 cell (L1210/R83) selected in the presence of the lipophilic antifolate, metoprine, and a concentration of the natural diastereoisomer of 5-formyltetrahydrofolate, lL5CHO-folateH4, suboptimum for growth exhibited a 35-fold increase compared to parental L1210 cells in one-carbon, reduced folate transport. This was evidenced by the increase in Vmax for [3H]MTX (methotrexate) influx and a commensurate increase in the amount of the 46 kilodalton (kDa) transport protein and reduced folate carrier (RFC-1) mRNA. The variant is resistant to lipophilic antifolates, but shows collateral sensitivity to classical folate analogues. Karyotype analysis of L1210/R83 cells revealed the presence of several new chromosome abnormalities. One of these was a large, submetacentric marker chromosome comprising a normal #10 and a longer, abnormally banded arm of uncertain origin which exhibited an interstitial, palely staining, HSR-like segment. The results of Southern and Northern blotting showed that the RFC-1 gene copy number and RNA transcript level were markedly increased (30-35 fold) in L1210/R83 cells. Fluorescence in situ hybridization (FISH) analysis revealed that the HSR-like segment in these cells was the site of amplified RFC-1 genes. Independent revertant subclones, obtained following growth in the absence of selection pressure, showed four- to 12-fold decreases in [3H]MTX influx Vmax and in amount of NHS (N-hydroxysuccinimide)-[3H]MTX affinity labeled one-carbon, reduced folate transporter compared to L1210/R83 cells. RFC-1 gene copy number also decreased, and the mean length of the HSR in these revertants declined 1.6- to 5-fold. Based upon genomic nucleotide sequencing, the RFC-1 gene in the normal mouse genome was localized to chromosome 10 in close association with the alpha 1 (Col18a1) collagen gene at 10B3(locus 41cM). The close association of these genes was confirmed by other data showing that the alpha 1 collagen gene was co-amplified in L1210/R83 cells. These results document the amplification at the site of a putative HSR in an L1210 cell variant of the RFC-1 gene regulating expression of the one-carbon, reduced folate transporter.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0165-4608
pubmed:author
pubmed:issnType
Print
pubmed:volume
105
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
29-38
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:9689927-Animals, pubmed-meshheading:9689927-Carrier Proteins, pubmed-meshheading:9689927-Chromosome Aberrations, pubmed-meshheading:9689927-Chromosome Disorders, pubmed-meshheading:9689927-Chromosome Mapping, pubmed-meshheading:9689927-Chromosomes, Human, Pair 10, pubmed-meshheading:9689927-Drug Resistance, Neoplasm, pubmed-meshheading:9689927-Folic Acid Antagonists, pubmed-meshheading:9689927-Gene Amplification, pubmed-meshheading:9689927-Gene Dosage, pubmed-meshheading:9689927-Humans, pubmed-meshheading:9689927-Karyotyping, pubmed-meshheading:9689927-Leukemia L1210, pubmed-meshheading:9689927-Membrane Proteins, pubmed-meshheading:9689927-Membrane Transport Proteins, pubmed-meshheading:9689927-Mice, pubmed-meshheading:9689927-RNA, Messenger, pubmed-meshheading:9689927-Tetrahydrofolate Dehydrogenase, pubmed-meshheading:9689927-Tumor Cells, Cultured
pubmed:year
1998
pubmed:articleTitle
Chromosomal localization of the murine RFC-1 gene encoding a folate transporter and its amplification in an antifolate resistant variant overproducing the transporter.
pubmed:affiliation
Program in Cell Biology and Genetics, Graduate School of Medical Sciences, Cornell University, New York, New York, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.