Notch signaling promotes commitment of keratinocytes to differentiation and suppresses tumorigenesis. p63, a p53 family member, has been implicated in establishment of the keratinocyte cell fate and/or maintenance of epithelial self-renewal. Here we show that p63 expression is suppressed by Notch1 activation in both mouse and human keratinocytes through a mechanism independent of cell cycle withdrawal and requiring down-modulation of selected interferon-responsive genes, including IRF7 and/or IRF3. In turn, elevated p63 expression counteracts the ability of Notch1 to restrict growth and promote differentiation. p63 functions as a selective modulator of Notch1-dependent transcription and function, with the Hes-1 gene as one of its direct negative targets. Thus, a complex cross-talk between Notch and p63 is involved in the balance between keratinocyte self-renewal and differentiation. Normal tissue homeostasis is determined by a complex interplay between developmental signals and other cell regulatory pathways. Notch cell surface receptors and their ligands belonging to the Delta and Serrate/Jagged families play a crucial role in cell fate determination and differentiation, functioning in a cell-and context-specific manner (Artavanis-Tsakonas et al. 1999). In mammalian cells, Notch activation is generally thought to maintain stem cell potential and inhibit differentiation, thereby promoting carcinogenesis (Artavanis-Tsakonas et al. 1999). However, in specific cell types such as keratinocytes, increased Notch activity causes exit from the cell cycle and commitment to differentiation (Lowell et al. 2000;Rangarajan et al. 2001;Nickoloff et al. 2002), whereas down-modulation or loss of Notch1 function promotes carcinogenesis (Talora et al. 2002;Nicolas et al. 2003).In the human epidermis, localized expression of the Notch-ligand Delta in putative "stem cells" has been proposed to induce commitment of neighboring Notch1-expressing keratinocytes to a "transit-amplifying" phenotype, through a negative feedback mechanism of lateral inhibition (Lowell et al. 2000). On the other hand, in both mouse and human epidermis, Jagged 1/2, Notch1, and Notch2 are coexpressed in differentiating keratinocytes of the supra-basal layers, consistent with a positive feedback loop between these molecules that serves to reinforce and synchronize Notch activation with differentiation (Luo et al. 1997;Rangarajan et al. 2001;Nickoloff et al. 2002).The best characterized "canonical" pathway of Notch activation involves proteolytic cleavage and translocation of the cytoplasmic domain of the receptor to the nucleus, where it associates with the DNA-binding protein RBP-J (CBF-1, CSL), converting it from a repressor

Background: Cadmium-transformed cells have a property of apoptosis resistance. Results: Cadmium-transformed cells express high antioxidant enzymes and antiapoptotic proteins. Conclusion:The constitutive p62 and Nrf2 expressions of transformed cells result in a decrease in ROS generation, apoptosis resistance, and tumorigenesis. Significance: Constitutive expression of Nrf2/p62 is important in cadmium carcinogenesis and its possible prevention using these proteins.

Post-translational histone modifications play important roles in regulating gene expression programs, which in turn determine cell fate and lineage commitment during development. One such modification is histone ubiquitination, which primarily targets histone H2A and H2B. Although ubiquitination of H2A and H2B has been generally linked to gene silencing and gene activation, respectively, the functions of histone ubiquitination during eukaryote development are not well understood. Here, we identified USP12 and USP46 as histone H2A and H2B deubiquitinases that regulate Xenopus development. USP12 and USP46 prefer nucleosomal substrates and deubiquitinate both histone H2A and H2B in vitro and in vivo. WDR48, a WD40 repeat-containing protein, interacts with USP12 and USP46 and is required for the histone deubiquitination activity. Overexpression of either gene leads to gastrulation defects without affecting mesodermal cell fate, whereas knockdown of USP12 in Xenopus embryos results in reduction of a subset of mesodermal genes at gastrula stages. Immunohistochemical staining and chromatin immunoprecipitation assays revealed that USP12 regulates histone deubiquitination in the mesoderm and at specific gene promoters during Xenopus development. Taken together, this study identifies USP12 and USP46 as histone deubiquitinases for H2A and H2B and reveals that USP12 regulates Xenopus development during gastrula stages.Eukaryotic development requires precise control of gene expression patterns that are essential for cellular identity and differentiation (1, 2). Genomic DNA in eukaryotic cells is organized into a chromatin structure by association with histone and non-histone proteins (3, 4), and the structure of chromatin is believed to play a critical role in regulating chromatin-templated nuclear processes such as transcription (5, 6). Post-translational modifications of histones represent a major mechanism by which cells control the structure and function of chromatin. An increasing list of histone-modifying enzymes and histone modifications has been shown to be critical for normal development and to play causal roles in the pathogenesis of certain human diseases (7-9).Of the vast variety of histone modifications, histone ubiquitination is unique, in which a 76-amino acid bulky protein is attached primarily to histone H2A and H2B (10, 11). The recent characterization of ubiquitin ligase hPRC1L and deubiquitinase Ubp-M (USP16) for histone H2A revealed critical functions for this modification in gene silencing, X inactivation, cell cycle progression, and DNA damage repair (12-15). In addition to Ubp-M, 2A-DUB (MYSM1) and USP21 were also identified as H2A-specific deubiquitinases (16,17). These enzymes might function in different cellular processes, for example, 2A-DUB in androgen receptor-mediated gene activation and USP21 in liver regeneration (16,17). Recently, the Drosophila PcG gene calypso was found to encode a ubiquitin C-terminal hydrolase BAP1, which specifically deubiquitinates histone H2A and regulates Hox gene r...

Background: Arsenic induced cell transformation and carcinogenesis. Results: Arsenic-transformed cells have the property of apoptosis/autophagy resistance. Conclusion:The constitutive activation of Nrf2 in arsenic-transformed cells up-regulates antioxidants, decreases ROS generation, and causes apoptosis resistance and tumorigenesis. Significance: Antioncogenic role of inducible Nrf2 in normal cells and oncogenic role of constitutive activation of Nfr2 in cancer cells may increase our understanding of the mechanism of arsenic carcinogenesis and its prevention.

Abstract:Cold stimulation of Bailinggu's mycelia is the main factor that triggers primordia initiation for successful production of fruiting bodies under commercial cultivation. Yet, the molecular-level mechanisms involved in mycelia response to cold stimulation are still unclear. Here, we performed comparative transcriptomic analysis using RNA-Seq technology to better understand the gene expression regulation during different temporal stages of cold stimulation in Bailinggu. A total of 21,558 Bailinggu mycelia unigenes were de novo assembled and annotated from four libraries (control at 25˝C, plus cold stimulation treatments at´3˝C for a duration of 1-2 days, 5-6 days, and 9-10 days). GO and KEGG pathway analysis indicated that functional groups of differentially expressed unigenes associated with cell wall and membrane stabilization, calcium signaling and mitogen-activated protein kinases (MAPK) pathways, and soluble sugars and protein biosynthesis and metabolism pathways play a vital role in Bailinggu's response to cold stimulation. Six hundred and seven potential EST-based SSRs loci were identified in these unigenes, and 100 EST-SSR primers were randomly selected for validation. The overall polymorphism rate was 92% by using 10 wild strains of Bailinggu. Therefore, these results can serve as a valuable resource for a better understanding of the molecular mechanisms associated with Bailinggu's response to cold stimulation.