Dec 2013, Volume 4 Issue 12
    

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  • LETTER
    Hao Chang, Mei Han, Wenming Huang, Guifeng Wei, Juanjuan Chen, Peng R. Chen, Runsheng Chen, Junlong Zhang, Tao Xu, Pingyong Xu
  • LETTER
    Liang Zhang, Sun Zhao, Jinhong Duan, Yan Hu, Ning Gu, Haiyan Xu, Xian-Da Yang
  • LETTER
    Raju V.S. Rajala, Ammaji Rajala
  • LETTER
    Kaiqi Wu, Chaowei Shi, Juan Li, Haipeng Wang, Pan Shi, Liu Chen, Fangming Wu, Ying Xiong, Changlin Tian
  • LETTER
    Geng Meng, Xiaojing An, Sheng Ye, Yong Liu, Wenzhuang Zhu, Rongguang Zhang, Xiaofeng Zheng
  • PERSPECTIVE
    Lihua Wang, Yuxi Cao, Qing Tang, Guodong Liang
  • REVIEW
    Yurika Matsui, Zhi-Chun Lai

    Hippo signaling plays a crucial role in growth control and tumor suppression by regulating cell proliferation, apoptosis, and differentiation. How Hippo signaling is regulated has been under extensive investigation. Over the past three years, an increasing amount of data have supported a model of actin cytoskeleton blocking Hippo signaling activity to allow nuclear accumulation of a downstream effector, Yki/Yap/Taz. On the other hand, Hippo signaling negatively regulates actin cytoskeleton organization. This review provides insight on the mutual regulatory mechanisms between Hippo signaling and actin cytoskeleton for a tight control of cell behaviors during animal development, and points out outstanding questions for further investigations.

  • RESEARCH ARTICLE
    Xuejuan Wang, Jianye Wang, Zhenrui Ding, Jinhua Ji, Qianqian Sun, Gang Cai

    Mediator is a highly conserved large protein complex (25 proteins,>1000 kD a) and preeminently responsible for eukaryotic transcription, which contains a dissociable ‘Cdk8 module’. Although increasing evidence demonstrates that Cdk8 module plays both positive and negative roles in transcription regulation, the detailed structure, and subunit organization, molecular mechanism how it regulates transcription remain elusive. Here we used single-particle electron microscopy to characterize the structure and subunit organization of the Cdk8 module and illuminated the substantial mobility of the Med13 subunit results in the structural flexibility. The Cdk8 module interaction with core Mediator is concurrent with active transcription in vivo. An interaction with the Cdk8 module induces core Mediator into very extended conformation in vitro, which is presumed to be an active functional state of Mediator. Taken together, our results illuminated the detailed architecture of Cdk8 module, and suggested the Cdk8 module could positively regulate transcription by modulating Mediator conformation.

  • RESEARCH ARTICLE
    Demeng Sun, Qing Liu, Yao He, Chengliang Wang, Fangming Wu, Changlin Tian, Jianye Zang

    Mycosin-1 protease (MycP1) is a serine protease anchored to the inner membrane of Mycobacterium tuberculosis, and is essential in virulence factor secretion through the ESX-1 type VII secretion system (T7SS). Bacterial physiology studies demonstrated that MycP1 plays a dual role in the regulation of ESX-1 secretion and virulence, primarily through cleavage of its secretion substrate EspB. MycP1 contains a putative N-terminal inhibitory propeptide and a catalytic triad of Asp-His-Ser, classic hallmarks of a subtilase family serine protease. The MycP1 propeptide was previously reported to be initially inactive and activated after prolonged incubation. In this study, we have determined crystal structures of MycP1 with (MycP124-422) and without (MycP163-422) the propeptide, and conducted EspB cleavage assays using the two proteins. Very high structural similarity was observed in the two crystal structures. Interestingly, protease assays demonstrated positive EspB cleavage for both proteins, indicating that the putative propeptide does not inhibit protease activity. Molecular dynamic simulations showed higher rigidity in regions guarding the entrance to the catalytic site in MycP124-422 than in MycP163-422, suggesting that the putative propeptide might contribute to the conformational stability of the active site cleft and surrounding regions.

  • RESEARCH ARTICLE
    Yuchen Liu, Luming Zhao, Dameng Li, Yuan Yin, Chen-Yu Zhang, Jing Li, Yujing Zhang

    Tumor-associated macrophages (TAMs) mostly exhibit M2-like (alternatively activated) properties and play positive roles in angiogenesis and tumorigenesis. Vascular endothelial growth factor (VEGF) is a key angiogenic factor. During tumor development, TAMs secrete VEGF and other factors to promote angiogenesis; thus, anti-treatment against TAMs and VEGF can repress cancer development, which has been demonstrated in clinical trials and on an experimental level. In the present work, we show that miR-150 is an oncomir because of its promotional effect on VEGF. MiR-150 targets TAMs to up-regulate their secretion of VEGF in vitro. With the utilization of cell-derived vesicles, named microvesicles (MVs), we transferred antisense RNA targeted to miR-150 into mice and found that the neutralization of miR-150 down-regulates miR-150 and VEGF levels in vivo and attenuates angiogenesis. Therefore, we proposed the therapeutic potential of neutralizing miR-150 to treat cancer and demonstrated a novel, natural, microvesicle-based method for the transfer of nucleic acids.

  • RESEARCH ARTICLE
    Di-Jing Shi, Sheng Ye, Xu Cao, Rongguang Zhang, KeWei Wang

    In all six members of TRPV channel subfamily, there is an ankyrin repeat domain (ARD) in their intracellular Ntermini. Ankyrin (ANK) repeat, a common motif with typically 33 residues in each repeat, is primarily involved in protein-protein interactions. Despite the sequence similarity among the ARDs of TRPV channels, the structure of TRPV3-ARD, however, remains unknown. Here, we report the crystal structure of TRPV3-ARD solved at 1.95 ? resolution, which reveals six-ankyrin repeats. While overall structure of TRPV3-ARD is similar to ARDs from other members of TRPV subfamily; it, however, features a noticeable finger 3 loop that bends over and is stabilized by a network of hydrogen bonds and hydrophobic packing, instead of being flexible as seen in known TRPV-ARD structures. Electrophysiological recordings demonstrated that mutating key residues R225, R226, Q255, and F249 of finger 3 loop altered the channel activities and pharmacology. Taken all together, our findings show that TRPV3-ARD with characteristic finger 3 loop likely plays an important role in channel function and pharmacology.

  • RESEARCH ARTICLE
    Yang Yang, Ling Zhang, Heyuan Geng, Yao Deng, Baoying Huang, Yin Guo, Zhengdong Zhao, Wenjie Tan

    The newly emerged Middle East respiratory syndrome coronavirus (MERS-CoV) is a highly pathogenic respiratory virus with pathogenic mechanisms that may be driven by innate immune pathways. The goal of this study is to characterize the expression of the structural (S, E, M, N) and accessory (ORF 3, ORF 4a, ORF 4b, ORF 5) proteins of MERS-CoV and to determine whether any of these proteins acts as an interferon antagonist. Individual structural and accessory protein-coding plasmids with an N-terminal HA tag were constructed and transiently transfected into cells, and their native expression and subcellular localization were assessed using Wes tern blotting and indirect immunofluorescence. While ORF 4b demonstrated majorly nuclear localization, all of the other proteins demonstrated cytoplasmic localization. In addition, for the first time, our experiments revealed that the M, ORF 4a, ORF 4b, and ORF 5 proteins are potent interferon antagonists. Further examination revealed that the ORF 4a protein of MERS-CoV has the most potential to counteract the antiviral effects of IFN via the inhibition of both the interferon production (IFN-β promoter activity, IRF-3/7 and NF-κB activation) and ISRE promoter element signaling pathways. Together, our results provide new insights into the function and pathogenic role of the structural and accessory proteins of MERS-CoV.