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The functions of many open reading frames (ORFs) identified in genome-sequencing projects are unknown. New, whole-genome approaches are required to systematically determine their function. A total of 6925 Saccharomyces cerevisiae strains were constructed, by a high-throughput strategy, each with a precise deletion of one of 2026 ORFs (more than one-third of(More)
Fibroblast growth factor receptors (Fgfr) comprise a widely expressed family of developmental regulators implicated in oligodendrocyte (OL) maturation of the CNS. Fgfr2 is expressed by OLs in myelinated fiber tracks. In vitro, Fgfr2 is highly upregulated during OL terminal differentiation, and its activation leads to enhanced growth of OL processes and the(More)
The mechanism responsible for immunoglobulin class switch recombination is unknown. Previous work has shown that class switch sequences have the unusual property of forming RNA-DNA hybrids when transcribed in vitro. Here we show that the RNA-DNA hybrid structure that forms in vitro is an R-loop with a displaced guanine (G)-rich strand that is(More)
Craniosynostosis syndromes are autosomal dominant human skeletal diseases that result from various mutations in fibroblast growth factor receptor genes (Fgfrs). Apert syndrome (AS) is one of the most severe craniosynostosis syndromes and is associated with severe syndactyly of the hands and feet and with central nervous system malformations. AS is caused by(More)
Activation-induced deaminase (AID) is required for both immunoglobulin class switch recombination and somatic hypermutation. AID is known to deaminate cytidines in single-stranded DNA, but the relationship of this step to the class switch or somatic hypermutation processes is not entirely clear. We have studied the activity of a recombinant form of the(More)
Immunoglobulin (Ig) class switch recombination (CSR) is initiated by activation-induced cytidine deaminase (AID) that catalyzes numerous DNA cytosine deaminations within switch regions. The resulting uracils are processed by uracil base excision and/or mismatch repair enzymes that ultimately generate switch region DNA double-strand breaks (DSBs). Uracil(More)
V(D)J recombination is directed by recombination signal sequences. However, the flanking coding end sequence can markedly affect the frequency of the initiation of V(D)J recombination in vivo. Here we demonstrate that the coding end sequence effect can be qualitatively and quantitatively recapitulated in vitro with purified RAG proteins. We find that coding(More)
Endonuclease G (endo G) is one of the most abundant nucleases in eukaryotic cells. It is encoded in the nucleus and imported to the mitochondrial intermembrane space. This nuclease is active on single- and double-stranded DNA. We genetically disrupted the endo G gene in mice without disturbing a conserved, overlapping gene of unknown function that is(More)
Class switch recombination is the gene rearrangement process by which our B lymphocytes change from IgM production to IgG, IgA, or IgE. Unlike the well-characterized V(D)J recombination, the mechanism of class switch recombination has been largely enigmatic until very recent progress has begun to shed light on this gene rearrangement process. Progress has(More)
Ig class-switch recombination (CSR) is directed by the long and repetitive switch regions and requires activation-induced cytidine deaminase (AID). One of the conserved switch-region sequence motifs (AGCT) is a preferred site for AID-mediated DNA-cytosine deamination. By using somatic gene targeting and recombinase-mediated cassette exchange, we established(More)