University of California, Irvine

About: University of California, Irvine is a education organization based out in Irvine, California, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 47031 authors who have published 113602 publications receiving 5521832 citations. The organization is also known as: UC Irvine & UCI.

Association analysis identifies 65 new breast cancer risk loci

Abstract: Breast cancer risk is influenced by rare coding variants in susceptibility genes, such as BRCA1, and many common, mostly non-coding variants. However, much of the genetic contribution to breast cancer risk remains unknown. Here we report the results of a genome-wide association study of breast cancer in 122,977 cases and 105,974 controls of European ancestry and 14,068 cases and 13,104 controls of East Asian ancestry. We identified 65 new loci that are associated with overall breast cancer risk at P < 5 × 10-8. The majority of credible risk single-nucleotide polymorphisms in these loci fall in distal regulatory elements, and by integrating in silico data to predict target genes in breast cells at each locus, we demonstrate a strong overlap between candidate target genes and somatic driver genes in breast tumours. We also find that heritability of breast cancer due to all single-nucleotide polymorphisms in regulatory features was 2-5-fold enriched relative to the genome-wide average, with strong enrichment for particular transcription factor binding sites. These results provide further insight into genetic susceptibility to breast cancer and will improve the use of genetic risk scores for individualized screening and prevention.

Electronic business adoption by European firms: a cross-country assessment of the facilitators and inhibitors

Abstract: In this study, we developed a conceptual model for studying the adoption of electronic business (e-business or EB) at the firm level, incorporating six adoption facilitators and inhibitors, based on the technology-organization-environment theoretical framework. Survey data from 3100 businesses and 7500 consumers in eight European countries were used to test the proposed adoption model. We conducted confirmatory factor analysis to assess the reliability and validity of constructs. To examine whether adoption patterns differ across different e-business environments, we divided the full sample into high EB-intensity and low EB-intensity countries. After controlling for variations of industry and country effects, the fitted Iogit models demonstrated four findings: (1) Technology competence, firm scope and size, consumer readiness, and competitive pressure are significant adoption drivers, while lack of trading partner readiness is a significant adoption inhibitor. (2) As EB-intensity increases, two environmental factors - consumer readiness and lack of trading partner readiness - become less important, while competitive pressure remains significant. (3) In high EB-intensity countries, e-business is no longer a phenomenon dominated by large firms; as more and more firms engage in e-business, network effect works to the advantage of small firms. (4) Firms are more cautious in adopting e-business in high EB-intensity countries - it seems to suggest that the more informed firms are less aggressive in adopting e-business, a somehow surprising result. Explanations and implications are offered.

Genomewide analysis of PRC1 and PRC2 occupancy identifies two classes of bivalent domains

Abstract: In embryonic stem (ES) cells, bivalent chromatin domains with overlapping repressive (H3 lysine 27 tri-methylation) and activating (H3 lysine 4 tri-methylation) histone modifications mark the promoters of more than 2,000 genes. To gain insight into the structure and function of bivalent domains, we mapped key histone modifications and subunits of Polycomb-repressive complexes 1 and 2 (PRC1 and PRC2) genomewide in human and mouse ES cells by chromatin immunoprecipitation, followed by ultra high-throughput sequencing. We find that bivalent domains can be segregated into two classes—the first occupied by both PRC2 and PRC1 (PRC1-positive) and the second specifically bound by PRC2 (PRC2-only). PRC1-positive bivalent domains appear functionally distinct as they more efficiently retain lysine 27 tri-methylation upon differentiation, show stringent conservation of chromatin state, and associate with an overwhelming number of developmental regulator gene promoters. We also used computational genomics to search for sequence determinants of Polycomb binding. This analysis revealed that the genomewide locations of PRC2 and PRC1 can be largely predicted from the locations, sizes, and underlying motif contents of CpG islands. We propose that large CpG islands depleted of activating motifs confer epigenetic memory by recruiting the full repertoire of Polycomb complexes in pluripotent cells.

Inhibition of activity-dependent arc protein expression in the rat hippocampus impairs the maintenance of long-term potentiation and the consolidation of long-term memory

Abstract: It is widely believed that the brain processes information and stores memories by modifying and stabilizing synaptic connections between neurons. In experimental models of synaptic plasticity, such as long-term potentiation (LTP), the stabilization of changes in synaptic strength requires rapid de novo RNA and protein synthesis. Candidate genes, which could underlie activity-dependent plasticity, have been identified on the basis of their rapid induction in brain neurons. Immediate-early genes (IEGs) are induced in hippocampal neurons by high-frequency electrical stimulation that induces LTP and by behavioral training that results in long-term memory (LTM) formation. Here, we investigated the role of the IEGArc (also termed Arg3.1) in hippocampal plasticity. Arc protein is known to be enriched in dendrites of hippocampal neurons where it associates with cytoskeletal proteins (Lyford et al., 1995).Arc is also notable in that its mRNA and protein accumulate in dendrites at sites of recent synaptic activity (Steward et al., 1998). We used intrahippocampal infusions of antisense oligodeoxynucleotides to inhibit Arc protein expression and examined the effect of this treatment on both LTP and spatial learning. Our studies show that disruption of Arc protein expression impairs the maintenance phase of LTP without affecting its induction and impairs consolidation of LTM for spatial water task training without affecting task acquisition or short-term memory. Thus, Arc appears to play a fundamental role in the stabilization of activity-dependent hippocampal plasticity.

IFN-γ-Inducible Protein 10 (IP-10; CXCL10)-Deficient Mice Reveal a Role for IP-10 in Effector T Cell Generation and Trafficking

Abstract: IFN-γ-inducible protein 10 (IP-10, CXCL10), a chemokine secreted from cells stimulated with type I and II IFNs and LPS, is a chemoattractant for activated T cells. Expression of IP-10 is seen in many Th1-type inflammatory diseases, where it is thought to play an important role in recruiting activated T cells into sites of tissue inflammation. To determine the in vivo function of IP-10, we constructed an IP-10-deficient mouse (IP-10−/−) by targeted gene disruption. Immunological analysis revealed that IP-10−/− mice had impaired T cell responses. T cell proliferation to allogeneic and antigenic stimulation and IFN-γ secretion in response to antigenic challenge were impaired in IP-10−/− mice. In addition, IP-10−/− mice exhibited an impaired contact hypersensitivity response, characterized by decreased ear swelling and reduced inflammatory cell infiltrates. T cells recovered from draining lymph nodes also had a decreased proliferative response to Ag restimulation. Furthermore, IP-10−/− mice infected with a neurotropic mouse hepatitis virus had an impaired ability to control viral replication in the brain. This was associated with decreased recruitment of CD4+ and CD8+ lymphocytes into the brain, reduced levels of IFN-γ and the IFN-γ-induced chemokines monokine induced by IFN-γ (Mig, CXCL9) and IFN-inducible T cell α chemoattractant (I-TAC, CXCL11) in the brain, decreased numbers of virus-specific IFN-γ-secreting CD8+ cells in the spleen, and reduced levels of demyelination in the CNS. Taken together, our data suggest a role for IP-10 in both effector T cell generation and trafficking in vivo.