Abstract
FRAXA is one of a number of fragile sites in human chromosomes that are induced by agents like fluorodeoxyuridine (FdU) that affect intracellular thymidylate levels. FRAXA coincides with a >200 CGG*CCG repeat tract in the 5' UTR of the FMR1 gene, and alleles prone to fragility are associated with Fragile X (FX) syndrome, one of the leading genetic causes of intellectual disability. Using siRNA depletion, we show that ATR is involved in protecting the genome against FdU-induced chromosome fragility. We also show that FdU increases the number of gamma-H2AX foci seen in both normal and patient cells and increases the frequency with which the FMR1 gene colocalizes with these foci in patient cells. In the presence of FdU and KU55933, an ATM inhibitor, the incidence of chromosome fragility is reduced, suggesting that ATM contributes to FdU-induced chromosome fragility. Since both ATR and ATM are involved in preventing aphidicolin-sensitive fragile sites, our data suggest that the lesions responsible for aphidicolin-induced and FdU-induced fragile sites differ. FRAXA also displays a second form of chromosome fragility in absence of FdU, which our data suggest is normally prevented by an ATM-dependent process.
Publication types
-
Research Support, N.I.H., Intramural
MeSH terms
-
Aphidicolin / pharmacology
-
Ataxia Telangiectasia Mutated Proteins
-
Cell Cycle Proteins / antagonists & inhibitors
-
Cell Cycle Proteins / genetics
-
Cell Cycle Proteins / metabolism*
-
Cell Line
-
Chromosome Breakage
-
Chromosome Fragile Sites*
-
Chromosome Fragility*
-
DNA Damage*
-
DNA Repair
-
DNA-Binding Proteins / antagonists & inhibitors
-
DNA-Binding Proteins / metabolism*
-
Floxuridine / pharmacology
-
Fragile X Mental Retardation Protein / genetics
-
Fragile X Syndrome / enzymology
-
Fragile X Syndrome / genetics*
-
Gene Knockdown Techniques
-
Histones / analysis
-
Humans
-
Male
-
Morpholines / pharmacology
-
Protein Kinase Inhibitors / pharmacology
-
Protein Serine-Threonine Kinases / antagonists & inhibitors
-
Protein Serine-Threonine Kinases / genetics
-
Protein Serine-Threonine Kinases / metabolism*
-
Pyrones / pharmacology
-
Staurosporine / analogs & derivatives
-
Staurosporine / pharmacology
-
Tumor Suppressor Proteins / antagonists & inhibitors
-
Tumor Suppressor Proteins / metabolism*
Substances
-
2-morpholin-4-yl-6-thianthren-1-yl-pyran-4-one
-
Cell Cycle Proteins
-
DNA-Binding Proteins
-
FMR1 protein, human
-
H2AX protein, human
-
Histones
-
Morpholines
-
Protein Kinase Inhibitors
-
Pyrones
-
Tumor Suppressor Proteins
-
Floxuridine
-
Fragile X Mental Retardation Protein
-
Aphidicolin
-
7-hydroxystaurosporine
-
ATM protein, human
-
ATR protein, human
-
Ataxia Telangiectasia Mutated Proteins
-
Protein Serine-Threonine Kinases
-
Staurosporine