Project description:Disease-specific induced pluripotent stem (iPS) cells have been used for a model to analyze pathogenesis of the disease. In this study, we generated iPS cells derived from a fibroblastic cell line of ataxia telangiectasia (AT-iPS cells), a neurodegenerative, inherited disease with chromosomal instability and hypersensitivity to ionizing radiation. AT-iPS cells exhibited hypersensitivity to X-ray irradiation, one of the characteristics of the disease. Surprisingly, while parental ataxia telangiectasia cells exhibited significant chromosomal abnormalities, AT-iPS cells did not show any chromosomal instability in vitro, i.e. maintenance of intact chromosomes at least by 80 passages (560 days) probably due to robust stability of pluripotent stem cells such as iPS cells and embryonic stem cells. The whole exome analysis also showed comparable nucleotide substitution speed in AT-iPS cells. Interestingly, after longer period of AT-iPS implantation into immunodeficient mice, teratoma generated by AT-iPS cells exhibited telangiectasia and carcinogenesis that are two characteristic symptoms of ataxia telangiectasia. Taken together, AT-iPS cells would be a good model for ataxia telangiectasia to clarify pathogenesis of the disease, and may allow us to facilitate development of drugs that inhibit ataxia and hypersensitivity to ionizing radiation for therapeutic application.
Project description:Disease-specific induced pluripotent stem (iPS) cells have been used for a model to analyze pathogenesis of the disease. In this study, we generated iPS cells derived from a fibroblastic cell line of ataxia telangiectasia (AT-iPS cells), a neurodegenerative, inherited disease with chromosomal instability and hypersensitivity to ionizing radiation. AT-iPS cells exhibited hypersensitivity to X-ray irradiation, one of the characteristics of the disease. Surprisingly, while parental ataxia telangiectasia cells exhibited significant chromosomal abnormalities, AT-iPS cells did not show any chromosomal instability in vitro, i.e. maintenance of intact chromosomes at least by 80 passages (560 days) probably due to robust stability of pluripotent stem cells such as iPS cells and embryonic stem cells. The whole exome analysis also showed comparable nucleotide substitution speed in AT-iPS cells. Interestingly, after longer period of AT-iPS implantation into immunodeficient mice, teratoma generated by AT-iPS cells exhibited telangiectasia and carcinogenesis that are two characteristic symptoms of ataxia telangiectasia. Taken together, AT-iPS cells would be a good model for ataxia telangiectasia to clarify pathogenesis of the disease, and may allow us to facilitate development of drugs that inhibit ataxia and hypersensitivity to ionizing radiation for therapeutic application. The parental AT1OS fibroblast cells and four independent AT-iPS clones were subjected to Illumina HumanCytoSNP-12 v2.1 BeadChip analysis.
Project description:Disease-specific induced pluripotent stem (iPS) cells have been used for a model to analyze pathogenesis of the disease. We generated iPS cells derived from a fibroblastic cell line of ataxia telangiectasia (AT-iPS cells). In analysis of AT-iPS cells, the human wild-type iPS cell line (MRC5-iPS) was generated and cultured in the same conditions as the diseased iPS cell lines. It is an ideal control cell line for the disease and patient-specific iPS cell lines. Because MRC5-iPS cells exhibited considerable chromosomal abnormalities in vitro, we performed a structural alteration analysis by using a SNP genotyping array for MRC5-iPS cell line, Tic, at passage 15, passage 30, and passage 37.
Project description:Disease-specific induced pluripotent stem (iPS) cells have been used for a model to analyze pathogenesis of the disease. We generated iPS cells derived from a fibroblastic cell line of ataxia telangiectasia (AT-iPS cells). In analysis of AT-iPS cells, the human wild-type iPS cell line (MRC5-iPS) was generated and cultured in the same conditions as the diseased iPS cell lines. It is an ideal control cell line for the disease and patient-specific iPS cell lines. Because MRC5-iPS cells exhibited considerable chromosomal abnormalities in vitro, we performed a structural alteration analysis by using a SNP genotyping array for MRC5-iPS cell line, Tic, at passage 15, passage 30, and passage 37. The parental MRC-5 fibroblast cells and MRC-iPS 25 (Tic) were subjected to Illumina HumanCytoSNP-12 v2.1 BeadChip analysis.
Project description:Whole seedlings of wild type (4d) and atm mutants (4d) have been analyzed after a gamma ray irradiation of 0.75h, 1.5h, 3h & 5h (time course). Roots of wt (4d), atm (3d) and atr (4d) mutants have been analyzed after a 1h irradiation.<br><br> Ataxia Telangiectasia Mutated (ATM), encodes a large protein with a phosphatidylinositol 3-kinase (PI3K)-like domain at the C terminus (reviewed by Rotman and Shiloh, 1998). PI3K-related proteins make up a large family of Ser-Thr protein kinases, numerous members of which are involved in the regulation of cell cycle progression, responses to DNA damage, and the maintenance of genomic stability (Hoekstra, 1997). AtATM plays an essential role in meiosis and in the somatic response to DNA damage in plants, similar to the function of ATM in mammals and other eukaryotes.<br>Ataxia telangiectasia-mutated and Rad3-related (ATR) plays a central role in cell-cycle regulation, transmitting DNA damage signals to downstream effectors of cell-cycle progression.
Project description:Background & Aims: Loss of ataxia-telangiectasia mutated, occurring in patients with multiple primary malignancies, including pancreatic cancer, is associated with poor prognosis. This study investigated the detailed molecular mechanism through which ataxia-telangiectasia mutated expression affects the prognosis of pancreatic-cancer patients Methods: Ataxia-telangiectasia mutated and phosphorylated ataxia-telangiectasia mutated levels in pancreatic-cancer patients who underwent surgical resection were analyzed using immunohistochemistry staining. RNA sequencing was performed on ataxia-telangiectasia mutated-knockdown pancreatic-cancer cells to elucidate the mechanism underlying the involvement of ataxia-telangiectasia mutated in pancreatic cancer. Results: Immunohistochemical analysis showed that 15.3% and 27.8% of clinical samples had low levels of ataxia-telangiectasia mutated and phosphorylated ataxia-telangiectasia mutated, respectively. Low phosphorylated ataxia-telangiectasia mutated expression substantially reduced overall and disease-free survival in pancreatic-cancer patients. Loss of ataxia-telangiectasia mutated promoted MET and NTN1 over-expression via hypoxia-inducible factor-1α, thereby enhancing pancreatic-cancer cell proliferation and migration. Conclusions: These results demonstrate that the loss of ataxia-telangiectasia mutated activates downstream proto-oncogenes, inhibits apoptosis, and promotes tumor growth; moreover, loss of phosphorylated ataxia-telangiectasia mutated leads to poor prognosis in pancreatic-cancer patients. Thus, ataxia-telangiectasia mutated may serve as a potential molecular marker to monitor patient prognosis and as a potential target for pancreatic cancer therapy
Project description:ATM (ataxia telangiectasia mutated) kinase is crucial to a wide range of human developmental disorders and adult/pediatric malignancies. Its mutations are causally tied to ataxia telangiectasia, a multi-systemic congenital disorder mainly affecting brain and blood systems. We generated 4 separate ATM-knockout human pluripotent stem cell lines and differentiated them to form 3-dimensional brain cortical brain organoids. Brain cortical organoids are an excellent model of human developing cortex. Using these analyses, we identified ATM-dependent phosphorylation predominantly influences factors in neurogenesis, neuronal differentiation, cell morphogenesis, and microtubule cytoskeleton as well as kinases involved in ATM, BNDF, and WNT signaling, G2/M checkpoint, and p53 regulation. These findings have broad implications about diseases associated with ATM, including ataxia telangiectasia.
Project description:Human pluripotent stem cells (hPSCs) are now being used for both disease modeling and cell therapy. However, efficient homologous recombination (HR) is often crucial to develop isogenic control or reporter lines. Here we show that limited low dose irradiation (LDI) using either γ-ray or X-ray exposure (0.4 Gy) significantly enhances HR frequency, possibly through induction of DNA repair/recombination machinery including ataxia-telangiectasia mutated, Histone H2A.X and RAD51 proteins. LDI could also increase HR efficiency by over 30- fold when combined with the targeting tools zinc finger nucleases (ZFNs), transcription activatorâ??like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats (CRISPRs). Whole exome sequencing confirmed that the LDI to hPSCs did not induce gross genomic alterations, or affect cellular viability. Irradiated and targeted lines were karyotypically normal and made all differentiated lineages that continued to express green fluorescent protein targeted at the AAVS1 locus. This simple method allows higher throughput of new targeted hPSC lines that are crucial for the research community as this growing field develops. 4 samples
Project description:Genome instability is a potential limitation to the research and therapeutic application of induced pluripotent stem cells (iPSCs). Observed genomic variations reflect the combined activities of DNA damage, cellular DNA damage response (DDR), and selection pressure in culture. To understand the contribution of DDR on the distribution of copy number variations (CNVs) in iPSCs, we mapped CNVs of iPSCs with mutations in the central DDR gene ATM onto genome organization landscapes defined by genome-wide replication timing profiles. We show that following reprogramming the early and late replicating genome is differentially affected by CNVs in ATM deficient iPSCs relative to wild type iPSCs. Specifically, the early replicating regions had increased CNV losses during retroviral reprogramming. This differential CNV distribution was not present after later passage or after episomal reprogramming. Comparison of different reprogramming methods in the setting of defective DNA damage response reveals unique vulnerability of early replicating open chromatin to retroviral vectors. We isolated RNA from Ataxia-telangiectasia (A-T) patient fibroblast derived iPS cells and A-T patient fibroblasts for hybridization to the Affymetrix gene expression microarrays.