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  • Induced pluripotent stem cells from highly endangered species. 21892153

    For some highly endangered species there are too few reproductively capable animals to maintain adequate genetic diversity, and extraordinary measures are necessary to prevent extinction. We report generation of induced pluripotent stem cells (iPSCs) from two endangered species: a primate, the drill, Mandrillus leucophaeus and the nearly extinct northern white rhinoceros, Ceratotherium simum cottoni. iPSCs may eventually facilitate reintroduction of genetic material into breeding populations.
    Document Type:
    Reference
    Product Catalog Number:
    CBL171
    Product Catalog Name:
    Anti-Actin Antibody, smooth muscle, clone ASM-1

  • Mismatch repair-dependent transcriptome changes in human cells treated with the methylating agent N-methyl-n'-nitro-N-nitrosoguanidine. 14678970

    DNA mismatch repair (MMR) plays a key role in the cytotoxic response of human cells to methylating agents, however, the cascade of events leading to cell cycle arrest and cell death has yet to be characterized. We studied the role of MMR in the transcriptional response to DNA methylation damage in two human cellular models: (a). the lymphoblastoid cell line TK6 and its derivative MT1, which is mutated in the MMR gene hMSH6; and (b). the epithelial cell line 293T Lalpha in which the expression of the MMR gene hMLH1 can be tightly regulated and p53 is inactivated. Upon N-methyl-N'-nitro-N-nitrosoguanidine treatment, only cells with functional MMR were killed, but the type of cytotoxic response differed. In TK6 cells, S-phase arrest and apoptosis were accompanied by a dramatic change in gene expression, notably, an up-regulation of several genes encoding growth inhibitors and proapoptotic factors both p53 dependent and independent. In contrast, the MMR-dependent transcriptional response in 293T Lalpha cells was substantially less pronounced than in TK6 cells, despite an efficient induction of a G(2)-M checkpoint and nonapoptotic cell death. Thus, we demonstrate that in human cells of different origin, MMR-mediated killing by methylating agents occurs through different pathways and regardless of the p53 status. Moreover, once DNA methylation damage has been processed by the MMR system, tumor cells might be committed to die, although one or more of their signaling pathways are impaired.
    Document Type:
    Reference
    Product Catalog Number:
    05-345
    Product Catalog Name:
    Anti-p21/WAF1/Cip1 Antibody

  • Ect2 and MgcRacGAP regulate the activation and function of Cdc42 in mitosis. 15642749

    Although Rho regulates cytokinesis, little was known about the functions in mitosis of Cdc42 and Rac. We recently suggested that Cdc42 works in metaphase by regulating bi-orient attachment of spindle microtubules to kinetochores. We now confirm the role of Cdc42 by RNA interference and identify the mechanisms for activation and down-regulation of Cdc42. Using a pull-down assay, we found that the level of GTP-Cdc42 elevates in metaphase, whereas the level of GTP-Rac does not change significantly in mitosis. Overexpression of dominant-negative mutants of Ect2 and MgcRacGAP, a Rho GTPase guanine nucleotide exchange factor and GTPase activating protein, respectively, or depletion of Ect2 by RNA interference suppresses this change of GTP-Cdc42 in mitosis. Depletion of Ect2 also impairs microtubule attachment to kinetochores and causes prometaphase delay and abnormal chromosomal segregation, as does depletion of Cdc42 or expression of the Ect2 and MgcRacGAP mutants. These results suggest that Ect2 and MgcRacGAP regulate the activation and function of Cdc42 in mitosis.
    Document Type:
    Reference
    Product Catalog Number:
    05-389
    Product Catalog Name:
    Anti-Rac1 Antibody, clone 23A8

  • Wnt4 inhibits beta-catenin/TCF signalling by redirecting beta-catenin to the cell membrane. 17976036

    BACKGROUND INFORMATION: During embryonic development, beta-catenin is central both to the transcriptional activation of Wnt [wingless-type MMTV (murine-mammary-tumour virus) integration site family] target genes and as a mediator of cell-cell adhesion. Signals that regulate its levels and subcellular localization are critical. One mechanism of Wnt signalling results in stabilization of beta-catenin protein, which leads to its translocation into the nucleus, where it interacts with TCF (T-cell factor, HMG box) and activates transcription of target genes. Less well understood are mechanisms of Wnt signalling that do not involve beta-catenin stabilization and result in inhibition of beta-catenin-mediated transcription. RESULTS: Here, we show that a member of the Wnt protein family, Wnt4 (Wnt, member 4), regulates the subcellular localization of beta-catenin, redirecting it to the cell membrane. Unique among Wnts, this action does not affect the stability of beta-catenin but does prohibit its involvement in TCF gene transactivation. CONCLUSIONS: This novel mechanism suggests that Wnt4 acts as a switch between the two modes of beta-catenin function, transcriptional activation and cell-cell adhesion.
    Document Type:
    Reference
    Product Catalog Number:
    05-665
    Product Catalog Name:
    Anti-Active-β-Catenin (Anti-ABC) Antibody, clone 8E7

  • High-efficiency siRNA-based gene knockdown in human embryonic stem cells. 20978109

    Loss-of-function studies in human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) via nonviral approaches have been largely unsuccessful. Here we report a simple and cost-effective method for high-efficiency delivery of plasmids and siRNAs into hESCs and iPSCs. Using this method for siRNA delivery, we achieve greater than 90% reduction in the expression of the stem cell factors Oct4 and Lin28, and observe cell morphological and staining pattern changes, characteristics of hESC differentiation, as a result of Oct4 knockdown.
    Document Type:
    Reference
    Product Catalog Number:
    AB3209
    Product Catalog Name:
    Anti-Oct-4 Antibody

  • Involvement of cyclin-dependent kinase-5 in the kainic acid-mediated degeneration of glutamatergic synapses in the rat hippocampus. 21978141

    Increased levels of glutamate causing excitotoxic damage accompany neurological disorders such as ischemia/stroke, epilepsy and some neurodegenerative diseases. Cyclin-dependent kinase-5 (Cdk5) is important for synaptic plasticity and is deregulated in neurodegenerative diseases. However, the mechanisms by which kainic acid (KA)-induced excitotoxic damage involves Cdk5 in neuronal injury are not fully understood. In this work, we have thus studied involvement of Cdk5 in the KA-mediated degeneration of glutamatergic synapses in the rat hippocampus. KA induced degeneration of mossy fiber synapses and decreased glutamate receptor (GluR)6/7 and post-synaptic density protein 95 (PSD95) levels in rat hippocampus in vivo after intraventricular injection of KA. KA also increased the cleavage of Cdk5 regulatory protein p35, and Cdk5 phosphorylation in the hippocampus at 12?h after treatment. Studies with hippocampal neurons in?vitro showed a rapid decline in GluR6/7 and PSD95 levels after KA treatment with the breakdown of p35 protein and phosphorylation of Cdk5. These changes depended on an increase in calcium as shown by the chelators 1,2-bis(o-aminophenoxy)ethane-N,N,N?',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM) and glycol-bis (2-aminoethylether)-N,N,N?',N?'-tetra-acetic acid. Inhibition of Cdk5 using roscovitine or employing dominant-negative Cdk5 and Cdk5 silencing RNA constructs counteracted the decreases in GluR6/7 and PSD95 levels induced by KA in hippocampal neurons. The dominant-negative Cdk5 was also able to decrease neuronal degeneration induced by KA in cultured neurons. The results show that Cdk5 is essentially involved in the KA-mediated alterations in synaptic proteins and in cell degeneration in hippocampal neurons after an excitotoxic injury. Inhibition of pathways activated by Cdk5 may be beneficial for treatment of synaptic degeneration and excitotoxicity observed in various brain diseases.
    Document Type:
    Reference
    Product Catalog Number:
    05-364
    Product Catalog Name:
    Anti-Cdk5 Antibody, clone DC17