Linked Life Data

21876188

Source:http://linkedlifedata.com/resource/pubmed/id/21876188

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
37
pubmed:dateCreated
2011-9-14
pubmed:abstractText
The de novo and salvage dTTP pathways are essential for maintaining cellular dTTP pools to ensure the faithful replication of both mitochondrial and nuclear DNA. Disregulation of dTTP pools results in mitochondrial dysfunction and nuclear genome instability due to an increase in uracil misincorporation. In this study, we identified a de novo dTMP synthesis pathway in mammalian mitochondria. Mitochondria purified from wild-type Chinese hamster ovary (CHO) cells and HepG2 cells converted dUMP to dTMP in the presence of NADPH and serine, through the activities of mitochondrial serine hydroxymethyltransferase (SHMT2), thymidylate synthase (TYMS), and a novel human mitochondrial dihydrofolate reductase (DHFR) previously thought to be a pseudogene known as dihydrofolate reductase-like protein 1 (DHFRL1). Human DHFRL1, SHMT2, and TYMS were localized to mitochondrial matrix and inner membrane, confirming the presence of this pathway in mitochondria. Knockdown of DHFRL1 using siRNA eliminated DHFR activity in mitochondria. DHFRL1 expression in CHO glyC, a previously uncharacterized mutant glycine auxotrophic cell line, rescued the glycine auxotrophy. De novo thymidylate synthesis activity was diminished in mitochondria isolated from glyA CHO cells that lack SHMT2 activity, as well as mitochondria isolated from wild-type CHO cells treated with methotrexate, a DHFR inhibitor. De novo thymidylate synthesis in mitochondria prevents uracil accumulation in mitochondrial DNA (mtDNA), as uracil levels in mtDNA isolated from glyA CHO cells was 40% higher than observed in mtDNA isolated from wild-type CHO cells. These data indicate that unlike other nucleotides, de novo dTMP synthesis occurs within mitochondria and is essential for mtDNA integrity.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
1091-6490
pubmed:author
pubmed:issnType
Electronic
pubmed:day
13
pubmed:volume
108
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
15163-8
pubmed:meshHeading
pubmed-meshheading:21876188-Amino Acid Sequence, pubmed-meshheading:21876188-Animals, pubmed-meshheading:21876188-Biosynthetic Pathways, pubmed-meshheading:21876188-CHO Cells, pubmed-meshheading:21876188-Cricetinae, pubmed-meshheading:21876188-Cricetulus, pubmed-meshheading:21876188-DNA, Mitochondrial, pubmed-meshheading:21876188-Gene Expression Regulation, pubmed-meshheading:21876188-Glycine, pubmed-meshheading:21876188-Humans, pubmed-meshheading:21876188-Mammals, pubmed-meshheading:21876188-Mitochondria, pubmed-meshheading:21876188-Molecular Sequence Data, pubmed-meshheading:21876188-Protein Transport, pubmed-meshheading:21876188-Sequence Alignment, pubmed-meshheading:21876188-Tetrahydrofolate Dehydrogenase, pubmed-meshheading:21876188-Thymidine Monophosphate, pubmed-meshheading:21876188-Thymidylate Synthase, pubmed-meshheading:21876188-Thymine Nucleotides, pubmed-meshheading:21876188-Uracil
pubmed:year
2011
pubmed:articleTitle
Identification of a de novo thymidylate biosynthesis pathway in mammalian mitochondria.
pubmed:affiliation
Division of Nutritional Sciences, Cornell University, 127 Savage Hall, Ithaca, NY 14853, USA.
pubmed:publicationType
Journal Article, Research Support, N.I.H., Extramural