Fuyuki Ishikawa

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Telomeres are essential for genome integrity. scRap1 (S. cerevisiae Rap1) directly binds to telomeric DNA and regulates telomere length and telomere position effect (TPE) by recruiting two different groups of proteins to its RCT (Rap1 C-terminal) domain. The first group, Rif1 and Rif2, regulates telomere length. The second group, Sir3 and Sir4, is involved(More)
Telomeres are specialized chromatin structures that protect chromosomal ends. Protection of telomeres 1 (Pot1) binds to the telomeric G-rich overhang, thereby protecting telomeres and regulating telomerase. Mammalian POT1 and TPP1 interact and constitute part of the six-protein shelterin complex. Here we report that Tpz1, the TPP1 homolog in fission yeast,(More)
Budding yeast Cdc13, Stn1, and Ten1 form the CST complex to protect telomeres from lethal DNA degradation. It remains unknown whether similar complexes are conserved in higher eukaryotes or not. Here we isolated mammalian STN1 and TEN1 homologs and CTC1 (conserved telomere maintenance component 1). The three proteins contain putative OB-fold domains and(More)
DNA methyltransferases Dnmt1, Dnmt3a and Dnmt3b cooperatively regulate cytosine methylation in CpG dinucleotides in mammalian genomes, providing an epigenetic basis for gene silencing and maintenance of genome integrity. Proper CpG methylation is required for the normal growth of various somatic cell types, indicating its essential role in the basic(More)
BACKGROUND Cellular senescence is a state of irreversible growth arrest shown by normal cells, and has been most extensively studied in replicative senescence caused by telomere shortening. Several conditions, including oncogenic Ras over-expression and inappropriate culture conditions, also induce senescence without telomere shortening. However, it remains(More)
Various stimuli, such as telomere dysfunction and oxidative stress, can induce irreversible cell growth arrest, which is termed 'cellular senescence'. This response is controlled by tumor suppressor proteins such as p53 and pRb. There is also evidence that senescent cells promote changes related to aging or age-related diseases. Here we show that p53(More)
Dendrites allow neurons to integrate sensory or synaptic inputs, and the spatial disposition and local density of branches within the dendritic arbor limit the number and type of inputs. Drosophila melanogaster dendritic arborization (da) neurons provide a model system to study the genetic programs underlying such geometry in vivo. Here we report that(More)
Cellular senescence is a tumor-suppressing mechanism that is accompanied by characteristic chromatin condensation called senescence-associated heterochromatic foci (SAHFs). We found that individual SAHFs originate from individual chromosomes. SAHFs do not show alterations of posttranslational modifications of core histones that mark condensed chromatin in(More)
BACKGROUND The telomere is a specialized heterochromatin conserved among eukaryotes. However, it remains unknown how heterochromatin protein 1 (HP1) is recruited to telomeres and how telomere heterochromatin is formed. In fission yeast, the RNAi (RNA interference)-RITS (RNA-induced initiation of transcriptional silencing) pathway initiates heterochromatin(More)
Telomere maintenance is essential for continued cell proliferation. Although most cells accomplish this by activating telomerase, a subset of immortalized tumors and cell lines do so in a telomerase-independent manner, a process called alternative lengthening of telomeres (ALT). DNA recombination has been shown to be involved in ALT, but the precise(More)