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941.
Macias H Moran A Samara Y Moreno M Compton JE Harburg G Strickland P Hinck L 《Developmental cell》2011,20(6):827-840
In the field of breast biology, there is a growing appreciation for the "gatekeeping function" of basal cells during development and disease processes yet mechanisms regulating the generation of these cells are poorly understood. Here, we report that the proliferation of basal cells is controlled by SLIT/ROBO1 signaling and that production of these cells regulates outgrowth of mammary branches. We identify the negative regulator TGF-β1 upstream of Robo1 and show that it induces Robo1 expression specifically in the basal layer, functioning together with SLIT2 to restrict branch formation. Loss of SLIT/ROBO1 signaling in this layer alone results in precocious branching due to a surplus of basal cells. SLIT2 limits basal cell proliferation by inhibiting canonical WNT signaling, increasing the cytoplasmic and membrane pools of β-catenin at the expense of its nuclear pool. Together, our studies provide mechanistic insight into how specification of basal cell number influences branching morphogenesis. 相似文献
942.
Lauranell H Burch Yong Yang Joan F Sterling Steven A Roberts Frank G Chao Hong Xu Leilei Zhang Jesse Walsh Michael A Resnick Piotr A Mieczkowski Dmitry A Gordenin 《Cell cycle (Georgetown, Tex.)》2011,10(7):1073-1085
Genome instability continuously presents perils of cancer, genetic disease and death of a cell or an organism. At the same time, it provides for genome plasticity that is essential for development and evolution. We address here the genome instability confined to a small fraction of DNA adjacent to free DNA ends at uncapped telomeres and double-strand breaks. We found that budding yeast cells can tolerate nearly 20 kilobase regions of subtelomeric single-strand DNA that contain multiple UV-damaged nucleotides. During restoration to the double-strand state, multiple mutations are generated by error-prone translesion synthesis. Genome-wide sequencing demonstrated that multiple regions of damage-induced localized hypermutability can be tolerated, which leads to the simultaneous appearance of multiple mutation clusters in the genomes of UV-irradiated cells. High multiplicity and density of mutations suggest that this novel form of genome instability may play significant roles in generating new alleles for evolutionary selection as well as in the incidence of cancer and genetic disease.Key words: hypermutability, evolution, DNA damage and repair, single-strand DNA, double-strand breaks 相似文献
943.
Early hominids searched for dispersed food sources in a patchy, uncertain environment, and modern humans encounter equivalent spatial-temporal coordination problems on a daily basis. A fundamental, but untested assumption is that our evolved capacity for communication is integral to our success in such tasks, allowing information exchange and consensus decisions based on mutual consideration of pooled information. Here we examine whether communication enhances group performance in humans, and test the prediction that consensus decision-making underlies group success. We used bespoke radio-tagging methodology to monitor the incremental performance of communicating and non-communicating human groups (small group sizes of two to seven individuals), during a social foraging experiment. We found that communicating groups (n = 22) foraged more effectively than non-communicating groups (n = 21) and were able to reach consensus decisions (an 'agreement' on the most profitable foraging resource) significantly more often than non-communicating groups. Our data additionally suggest that gesticulations among group members played a vital role in the achievement of consensus decisions, and therefore highlight the importance of non-verbal signalling of intentions and desires for successful human cooperative behaviour. 相似文献
944.
Lindsay French 《Ethnos》2013,78(2):170-191
The recent explosion of theft in sculpture from Angkor era temples in Cambodia raises questions about the circumstances that make such destructive acts possible at these historically sacred Khmer sites. This paper looks at the commodification of and traffic in temple sculpture in relation to a particular way of classifying and evaluating the temples. It considers different systems of classification and theories of value that have converged on the temples at different moments in history, and the politics behind the ascendance of particular value systems. It uses Arjun Appadurai's concept of a ‘regime of value’ to illuminate the intersection of many different value systems at the temples today, and to shed light on the contradictory mix of conservation and exploitation, scholarship and commerce, preservation and development, which co‐exist at these now‐international heritage sites. 相似文献
945.
Sameer A. Greenall John D. Bentley Lesley A. Pearce Judith A. Scoble Lindsay G. Sparrow Nicola A. Bartone Xiaowen Xiao Robert C. Baxter Leah J. Cosgrove Timothy E. Adams 《The Journal of biological chemistry》2013,288(1):59-68
Insulin-like growth factor II (IGF-II) is a major embryonic growth factor belonging to the insulin-like growth factor family, which includes insulin and IGF-I. Its expression in humans is tightly controlled by maternal imprinting, a genetic restraint that is lost in many cancers, resulting in up-regulation of both mature IGF-II mRNA and protein expression. Additionally, increased expression of several longer isoforms of IGF-II, termed “pro” and “big” IGF-II, has been observed. To date, it is ambiguous as to what role these IGF-II isoforms have in initiating and sustaining tumorigenesis and whether they are bioavailable. We have expressed each individual IGF-II isoform in their proper O-glycosylated format and established that all bind to the IGF-I receptor and both insulin receptors A and B, resulting in their activation and subsequent stimulation of fibroblast proliferation. We also confirmed that all isoforms are able to be sequestered into binary complexes with several IGF-binding proteins (IGFBP-2, IGFBP-3, and IGFBP-5). In contrast to this, ternary complex formation with IGFBP-3 or IGFBP-5 and the auxillary protein, acid labile subunit, was severely diminished. Furthermore, big-IGF-II isoforms bound much more weakly to purified ectodomain of the natural IGF-II scavenging receptor, IGF-IIR. IGF-II isoforms thus possess unique biological properties that may enable them to escape normal sequestration avenues and remain bioavailable in vivo to sustain oncogenic signaling. 相似文献
946.
Daniel Lim Daniel A. Gold Lindsay Julien Emily E. Rosowski Wendy Niedelman Michael B. Yaffe Jeroen P. J. Saeij 《The Journal of biological chemistry》2013,288(48):34968-34980
At least a third of the human population is infected with the intracellular parasite Toxoplasma gondii, which contributes significantly to the disease burden in immunocompromised and neutropenic hosts and causes serious congenital complications when vertically transmitted to the fetus. Genetic analyses have identified the Toxoplasma ROP18 Ser/Thr protein kinase as a major factor mediating acute virulence in mice. ROP18 is secreted into the host cell during the invasion process, and its catalytic activity is required for the acute virulence phenotype. However, its precise molecular function and regulation are not fully understood. We have determined the crystal structure of the ROP18 kinase domain, which is inconsistent with a previously proposed autoinhibitory mechanism of regulation. Furthermore, a sucrose molecule bound to our structure identifies an additional ligand-binding pocket outside of the active site cleft. Mutational analysis confirms an important role for this pocket in virulence. 相似文献
947.
948.
Gareth A. Roberts Patrick J. Houston John H. White Kai Chen Augoustinos S. Stephanou Laurie P. Cooper David T.F. Dryden Jodi A. Lindsay 《Nucleic acids research》2013,41(15):7472-7484
A limited number of Methicillin-resistant Staphylococcus aureus (MRSA) clones are responsible for MRSA infections worldwide, and those of different lineages carry unique Type I restriction-modification (RM) variants. We have identified the specific DNA sequence targets for the dominant MRSA lineages CC1, CC5, CC8 and ST239. We experimentally demonstrate that this RM system is sufficient to block horizontal gene transfer between clinically important MRSA, confirming the bioinformatic evidence that each lineage is evolving independently. Target sites are distributed randomly in S. aureus genomes, except in a set of large conjugative plasmids encoding resistance genes that show evidence of spreading between two successful MRSA lineages. This analysis of the identification and distribution of target sites explains evolutionary patterns in a pathogenic bacterium. We show that a lack of specific target sites enables plasmids to evade the Type I RM system thereby contributing to the evolution of increasingly resistant community and hospital MRSA. 相似文献
949.
950.
Peg?AllenEmail author Sonia?Sequeira Rebekah?R?Jacob Adriano?Akira?Ferreira?Hino Katherine?A?Stamatakis Jenine?K?Harris Lindsay?Elliott Jon?F?Kerner Ellen?Jones Maureen?Dobbins Elizabeth?A?Baker Ross?C?Brownson 《Implementation science : IS》2013,8(1):141