| 1. |
- Richards, Stephen, et al.
(författare)
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Genome Sequence of the Pea Aphid Acyrthosiphon pisum
- 2010
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Ingår i: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 8:2, s. e1000313-
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Tidskriftsartikel (refereegranskat)abstract
- Aphids are important agricultural pests and also biological models for studies of insect-plant interactions, symbiosis, virus vectoring, and the developmental causes of extreme phenotypic plasticity. Here we present the 464 Mb draft genome assembly of the pea aphid Acyrthosiphon pisum. This first published whole genome sequence of a basal hemimetabolous insect provides an outgroup to the multiple published genomes of holometabolous insects. Pea aphids are host-plant specialists, they can reproduce both sexually and asexually, and they have coevolved with an obligate bacterial symbiont. Here we highlight findings from whole genome analysis that may be related to these unusual biological features. These findings include discovery of extensive gene duplication in more than 2000 gene families as well as loss of evolutionarily conserved genes. Gene family expansions relative to other published genomes include genes involved in chromatin modification, miRNA synthesis, and sugar transport. Gene losses include genes central to the IMD immune pathway, selenoprotein utilization, purine salvage, and the entire urea cycle. The pea aphid genome reveals that only a limited number of genes have been acquired from bacteria; thus the reduced gene count of Buchnera does not reflect gene transfer to the host genome. The inventory of metabolic genes in the pea aphid genome suggests that there is extensive metabolite exchange between the aphid and Buchnera, including sharing of amino acid biosynthesis between the aphid and Buchnera. The pea aphid genome provides a foundation for post-genomic studies of fundamental biological questions and applied agricultural problems.
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| 2. |
- Nava, Porfirio, et al.
(författare)
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IFN gamma-induced suppression of beta-catenin signaling : evidence for roles of Akt and 14.3.3 zeta
- 2014
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Ingår i: Molecular Biology of the Cell. - Bethesda, United States : American Society for Cell Biology. - 1059-1524 .- 1939-4586. ; 25:19, s. 2894-2904
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Tidskriftsartikel (refereegranskat)abstract
- The proinflammatory cytokine interferon gamma (IFNgamma ) influences intestinal epithelial cell (IEC) homeostasis in a biphasic manner by acutely stimulating proliferation that is followed by sustained inhibition of proliferation despite continued mucosal injury. beta-Catenin activation has been classically associated with increased IEC proliferation. However, we observed that IFNgamma inhibits IEC proliferation despite sustained activation of Akt/beta-catenin signaling. Here we show that inhibition of Akt/beta-catenin-mediated cell proliferation by IFNgamma is associated with the formation of a protein complex containing phosphorylated beta-catenin 552 (pbeta-cat552) and 14.3.3zeta. Akt1 served as a bimodal switch that promotes or inhibits beta-catenin transactivation in response to IFNgamma stimulation. IFNgamma initially promotes beta-catenin transactivation through Akt-dependent C-terminal phosphorylation of beta-catenin to promote its association with 14.3.3zeta. Augmented beta-catenin transactivation leads to increased Akt1 protein levels, and active Akt1 accumulates in the nucleus, where it phosphorylates 14.3.3zeta to translocate 14.3.3zeta/beta-catenin from the nucleus, thereby inhibiting beta-catenin transactivation and IEC proliferation. These results outline a dual function of Akt1 that suppresses IEC proliferation during intestinal inflammation.
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| 3. |
- Neumann, Philipp-Alexander, et al.
(författare)
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Gut commensal bacteria and regional Wnt gene expression in the proximal versus distal colon
- 2014
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Ingår i: American Journal of Pathology. - : Elsevier. - 0002-9440 .- 1525-2191. ; 184:3, s. 592-9
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Tidskriftsartikel (refereegranskat)abstract
- Regional expression of Wingless/Int (Wnt) genes plays a central role in regulating intestinal development and homeostasis. However, our knowledge of such regional Wnt proteins in the colon remains limited. To understand further the effect of Wnt signaling components in controlling intestinal epithelial homeostasis, we investigated whether the physiological heterogeneity of the proximal and distal colon can be explained by differential Wnt signaling. With the use of a Wnt signaling-specific PCR array, expression of 84 Wnt-mediated signal transduction genes was analyzed, and a differential signature of Wnt-related genes in the proximal versus distal murine colon was identified. Several Wnt agonists (Wnt5a, Wnt8b, and Wnt11), the Wnt receptor frizzled family receptor 3, and the Wnt inhibitory factor 1 were differentially expressed along the colon length. These Wnt signatures were associated with differential epithelial cell proliferation and migration in the proximal versus distal colon. Furthermore, reduced Wnt/beta-catenin activity and decreased Wnt5a and Wnt11 expression were observed in mice lacking commensal bacteria, an effect that was reversed by conventionalization of germ-free mice. Interestingly, myeloid differentiation primary response gene 88 knockout mice showed decreased Wnt5a levels, indicating a role for Toll-like receptor signaling in regulating Wnt5a expression. Our results suggest that the morphological and physiological heterogeneity within the colon is in part facilitated by the differential expression of Wnt signaling components and influenced by colonization with bacteria.
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