In Vivo Epigenomic Profiling of Germ Cells Reveals Germ Cell Molecular Signatures

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Highlights? Modified small-scale ChIP-seq method applicable to small number of cells ? Genome-wide maps of H3K4me3, H3K27me3, H3K27ac, and H2BK20ac of germ cells in vivo ? Identification of active and inactive regulatory elements in germ cells in vivo ? Germ cell H3K27me3 regions are enriched for retrotransposon repeats     

In Vivo Imaging Reveals a Pioneer Wave of Monocyte Recruitment into Mouse Skin Wounds

The cells of the mononuclear phagocyte system are essential for the correct healing of adult skin wounds, but their specific functions remain ill-defined. The absence of granulation tissue immediately after skin injury makes it challenging to study the role of mononuclear phagocytes at the initiation of this inflammatory stage. To study their recruitment and migratory behavior within the wound bed, we developed a new model for real-time in vivo imaging of the wound, using transgenic mice that express green and cyan fluorescent proteins and specifically target monocytes. Within hours after the scalp injury, monocytes invaded the wound bed. The complete abrogation of this infiltration in monocyte-deficient CCR2^−/− mice argues for the involvement of classical monocytes in this process. Monocyte infiltration unexpectedly occurred as early as neutrophil recruitment did and resulted from active release from the bloodstream toward the matrix through microhemorrhages rather than transendothelial migration. Monocytes randomly scouted around the wound bed, progressively slowed down, and stopped. Our approach identified and characterized a rapid and earlier than expected wave of monocyte infiltration and provides a novel framework for investigating the role of these cells during early stages of wound healing.     

Bivalent Chromatin Marks Developmental Regulatory Genes in the Mouse Embryonic Germline In Vivo

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Enabled Negatively Regulates Diaphanous-Driven Actin Dynamics In Vitro and In Vivo

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Gambogic Acid Is a Tissue-Specific Proteasome Inhibitor In Vitro and In Vivo

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Highlights? GA is metabolized by CYP2E1 to produce a metabolite proteasome inhibitor ? Proteasome inhibition is required for GA’s cytotoxicity and anticancer activity ? GA is a more tissue-specific proteasome inhibitor than bortezomib/velcade ? GA is nontoxic to peripheral white blood cells compared to bortezomib     

Principles of E-Cadherin Supramolecular Organization In Vivo

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Pyramidal Neurons Derived from Human Pluripotent Stem Cells Integrate Efficiently into Mouse Brain Circuits In Vivo

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Estimating the Microtubule GTP Cap Size In Vivo

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Highlights? The microtubule (MT) GTP cap is ～750 tubulin subunits in vivo and extends over 1 μm ? EGFP brightness can be calibrated in vivo using GFP-tubulin signals from MTs ? The presence of GTP-tubulin in the MT lattice influences MT shortening and rescue ? MT tip trackers, like EB1, can be highly concentrated at the MT plus end (～100 μM)     

Studies on the Mechanisms Involved in Multistage Carcinogenesis in Mouse Skin

Skin tumors can be effectively induced in mice by the repetitive application of a carcinogen. The relative order of sensitivity to complete carcinogenesis is Sencar > CD-1 > C57BL/6 ≥ BALB/c ≥ ICR/Ha Swiss > C3H. Skin tumors in mice can also be induced by the sequential application of a sub-threshold dose of a carcinogen (initiation phase) followed by repetitive treatment with a weak or noncarcinogenic tumor promoter (promotion phase). The relative order of sensitivity to initiation-promotion is Sencar > > CD-1 > ICR/Ha Swiss ≥ Balb/c > C57BL/6 ≥ C3H ≥ DBA/2. The initiation phase requires only a single application of a carcinogen and is essentially an irreversible step, which probably involves a somatic cell mutation as is evidenced by a good correlation between the carcinogenicity of many chemical carcinogens and their mutagenic activities; the promotion stage, however, is initially reversible, later becoming irreversible. For strains and stocks of mice which respond to initiation-promotion, there is a good correlation between the tumor-initiating activities of polycyclic aromatic hydrocarbons (PAH) and their abilities to bind covalently to DNA. Potent inhibitors and stimulators of PAH tumor initiation appear to effect the level of the PAH diol epoxide bound to specific DNA adducts. However, when the binding of a given PAH to DNA is compared in various stocks and strains of mice, there is no correlation, since in those mice which are able to metabolize PAH, the amounts of carcinogen bound to DNA are similar. The phorbol ester tumor promoters have been shown to have several cellular and biochemical effects on the skin. Of all the observed phorbol ester related effects on the skin, the induction of epidermal cell proliferation, polyamines, prostagladins, and dark basal keratinocytes as well as other embryonic conditions appear to correlate the best with promotion. Mezerein, a weak promoter, was found to induce many cellular and biochemical changes similar to 12-O-tetradecanoylphorbol-13 acetate (TPA), especially epidermal hyperplasia and polyamines; however, it was not a potent inducer of dark cells. We recently found that promotion could be divided into at least two stages. The first stage (I) can be accomplished by limited treatment with TPA or the nonpromoting agents, 4-O-methyl TPA and the calcium ionophore A23187, and the second stage (II) by repetitive applications of mezerein. The dark basal cells appear to be important in the first stage of promotion, since TPA, 4-0-methyl TPA, and A23187 are potent inducers of dark cells. Fluocinolone acetonide (FA) was found to be a potent inhibitor of stage I and II. Retinoic acid (RA) was ineffective in Stage I but was a potent inhibitor of Stage II promotion, whereas tosyl phenylalanine chloromethylketone (TPCK) specifically inhibited Stage I. In addition, FA and TPCK effectively counteracted the appearance of dark basal keratinocytes but had very little effect on polyamines, whereas RA had no effect on dark cells but is a potent inhibitor of TPA-induced ornithine decarboxylase activity and subsequent putrescine formation. These results provide additional evidence for the importance of dark basal keratinocytes (primitive stem cells) in Stage I of promotion and indicate that most of the other cellular and biochemical responses normally associated with promotion (such as polyamines) are actually associated with Stage II of promotion. Although C57BL/6 mice are relatively resistant to initiation-promotion by PAH initiation and phorbol ester promotion, they are fairly sensitive to complete carcinogenesis by PAH. This suggests that the C57BL/6 mice are resistant to phorbol ester tumor promotion. Preliminary experiments suggest that C57BL/6 and Sencar mice respond qualitatively but not quantitatively to a single treatment with TPA.     

Molecular Co-occupancy Identifies Transcription Factor Binding Cooperativity In Vivo

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Inducible Stem-Cell-Derived Embryos Capture Mouse Morphogenetic Events In Vitro

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Hebbian Plasticity Guides Maturation of Glutamate Receptor Fields In Vivo

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Differential Synaptic Input to External Globus Pallidus Neuronal Subpopulations In Vivo

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