分类： 生物学 >> 生物物理学 >> 细胞生物学 提交时间： 2016-05-11
摘要： G-protein coupled receptors (GPCRs) play essential roles in signal transduction from the environment into the cell. While many structural features have been elucidated in great detail, a common functional mechanism on how the ligand-binding signal is converted into a conformational change on the cytoplasmic face resulting in subsequent activation of downstream effectors remain to be established. Based on available structural and functional data of the activation process in class-A GPCRs, we propose here that a change in protonation status, together with proton transfer via conserved structural elements located in the transmembrane region, are the key elements essential for signal transduction across the membrane.
分类： 药物科学 >> 结构生物学 提交时间： 2024-04-17
摘要： The adenosine A3 receptor (A3AR) belongs to a subfamily of G protein-coupled receptors and is an important therapeutic target for conditions including inflammation and cancer. The clinical compounds CF101 and CF102 are potent and selective A3AR agonists, but the structural basis of their recognition was unknown. Here we present the cryogenic electron microscopy structures of the full-length human A3AR bound to CF101 and CF102 at 3.3-3.2 Å resolution in complex with heterotrimeric Gi protein. These agonists bind within the orthosteric pocket, with their adenine components engaging in conserved interactions while their substituted 3-iodobenzyl groups exhibit different orientations. Swapping extracellular loop 3 (ECL3) of A3AR onto other adenosine receptor subtypes enabled CF101/CF102 binding and receptor activaton, and mutations in key residues, including His3.37, Ser5.42 and Ser6.52 that form a unique subpocket in A3AR, abolished receptor activation, highlighting these structural elements are critical for ligand selectivity. Compared to inactive A2AAR, the A3AR structures reveal conserved mechanism of receptor activation, including an outward shift of TM6. These structures provide key insights into molecular recognition and signaling mechanisms of A3AR, which should aid rational design of subtype-selective ligands targeting this important class of adenosine receptors.
分类： 生物学 >> 生物物理学 >> 生物力学与生物流变学 提交时间： 2016-05-15
Wan, Zhengpeng
Chen, Xiangjun
Chen, Yingjia
Wang, Jing
Cao, Yiyun
Liu, Wanli
Chen, Haodong
Wang, Fei
Tang, Zhuo
Ji, Qinghua
Lou, Jizhong
摘要： B lymphocytes use B cell receptors (BCRs) to sense the physical features of the antigens. However, the sensitivity and threshold for the activation of BCRs resulting from the stimulation by mechanical forces are unknown. Here, we addressed this question using a double-stranded DNA-based tension gauge tether system serving as a predefined mechanical force gauge ranging from 12 to 56 pN. We observed that IgM-BCR activation is dependent on mechanical forces and exhibits a multi-threshold effect. In contrast, the activation of isotype-switched IgG- or IgE-BCR only requires a low threshold of less than 12 pN, providing an explanation for their rapid activation in response to antigen stimulation. Mechanistically, we found that the cytoplasmic tail of the IgG-BCR heavy chain is both required and sufficient to account for the low mechanical force threshold. These results defined the mechanical force sensitivity and threshold that are required to activate different isotyped BCRs.
分类： 生物学 >> 生物物理学 >> 肿瘤学 提交时间： 2016-05-11
Hu, Shi
Guo, Huaizu
Qian, Weizhu
Hou, Sheng
Li, Bohua
Guo, Yajun
Hu, Shi
Guo, Huaizu
Qian, Weizhu
Hou, Sheng
Li, Bohua
Guo, Yajun
Hu, Shi
Sun, Yuna
Rao, Zihe
Hu, Shi
Sun, Yuna
Rao, Zihe
Lou, Zhiyong
Hu, Shi
摘要： Human epidermal growth factor receptors (HERs or ErbBs) play crucial roles in numerous cellular processes. ErbB2 is a key member of ErbB family, and its overexpression is recognized as a frequent molecular abnormality. In cancer, this overexpression correlates with aggressive disease and poor patient outcomes. Dimer-dependent phosphorylation is a key event for the signal transduction of ErbBs. However, the molecular mechanism of the dimerization of ErbB2 remains elusive. In the present work, we report the homodimer architecture of the ErbB2 extracellular domain (ECD) which is unique compared with other dimer-models of ErbBs. The structure of the ErbB2 ECD homodimer represents a "back to head" interaction, in which a protruding beta-hairpin arm in domain II of one ErbB2 protomer is inserted into a C-shaped pocket created by domains I-III of the adjacent ErbB2 protomer. This dimerized architecture and its impact on the phosphorylation of ErbB2 intracellular domain were further verified by a mutagenesis study. We also elucidated the different impacts of two clinically administered therapeutic antibodies, trastuzumab and pertuzumab, on ErbB2 dimerization. This information not only provides an understanding of the molecular mechanism of ErbBs dimerization but also elucidates ErbB2-targeted therapy at the molecular level.
分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： Asialoglycoprotein receptor (ASGP-R) is a hepatic membrane receptor that uniquely exists on the surface of mammalian hepatocytes, and has been used as target of liver functional imaging agents for many years. We labeled the Galactosyl-neoglycoalbumin (NGA) with 18F to get a PET molecular probe 18F-FB-NGA and evaluated its ability as a liver functional PET imaging agent. The 18F-FB-NGA was prepared with NGA by conjugation with N- succinimidyl-4-18F-fluorobenzoate (18F-SFB) and purified with PD-10 desalting column. The radiolabeling yield and radiochemical purity of 18F-FB-NGA were determined by radio-HPLC. Starting with 18F-F, the total time for 18F-FB -NGA was about 12010 min. The decay-corrected radiochemical yield is about 2530%. The radiochemical purity of purified 18F-FB-NGA was more than 98%. Labeled with 1851850 MBq 18F-SFB, the specific activity of 18F -FB- NGA was estimated to be 7.8378.3 TBq/mmol. Biodistribution of 18F-FB-NGA in normal mice was investigated after injection through the tail vein. The results showed that the liver accumulated 39.473.42 and 12.126.11%ID/g at 10 and 30 min after injection, respectively. Dynamic MicroPET images in mice were acquired with and without block after injection of the radiotracer, respectively. High liver activity accumulation was observed at 5 min after injection in normal group. On the contrary, the liver accumulation was significantly lower after block, indicating the specific binding to ASGP-R. 18F-FB-NGA is probably a potential PET liver imaging agent.
分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要： The 4,5-dioxo-4,5-dihydro-1H-pyrrolo(2,3-f)quinoline-2,7,9-tricarboxylic acid 2-ethyl ester 7,9-dimethyl ester (PQQE) was synthesized on the basis of Pyrroloquinoline quinine (PQQ). 99mTc-PQQE was prepared using stannous fluoride (SnF2) as reducing agent. Biological characteristics of 99mTc-PQQE include lipophilic and the charge properties were compared to 99mTc-PQQ. The biodistributions of 99mTc-PQQE in mice and brain regional distribution were performed. In vivo distribution of 99mTc-PQQE in mice indicates that the concentration ratio of drug and blood increases steadily over time. The major radioactivity may be metabolized by the hepatic and renal system. The elimination-phase half-time (t1/2) results indicate that the residence time of 99mTc-PQQE (203.92) in the body is twice as long as 99mTc-PQQ (100.45). The uptake of 99mTc-PQQE in brain was improved due to the ameliorating of charge and lipophilicity. The highest total regional brain uptake of 99mTc-PQQE was in the frontal lobe and hippocampus, where the NMDA receptor is very abundant. 99mTc-PQQE had a good target to nontarget ratio (hippocampus/cerebellum) which preserved a higher value (peak 4.0 at 120 min) from 60 min to 180 min after injection. In vitro autoradiographic results are in close agreement with the regional brain map. The enrichment can be blocked by N-methyl-D-aspartate receptor (NMDAR) redox modulatory site antagonists-ebselen (EB). This work suggests that 99mTc-PQQE has some specific targeting to the NMDA receptor.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
摘要： Herpes simplex virus (HSV) entry and cell-cell fusion require the envelope proteins gD, gH/gL and gB. We propose that receptor-activated conformational changes to gD activate gH/gL, which then triggers gB (the fusogen) into an active form. To study this dynamic process, we have adapted a dual split protein assay originally developed to study the kinetics of human immunodeficiency virus (HIV) mediated fusion. This assay uses a chimera of split forms of renilla luciferase (RL) and green fluorescent protein (GFP). Effector cells are co-transfected with the glycoproteins and one of the split reporters. Receptor-bearing target cells are transfected with the second reporter. Co-culture results in fusion and restoration of RL, which can convert a membrane permeable substrate into a luminescent product, thereby enabling one to monitor initiation and extent of fusion in live cells in real time. Restoration of GFP can also be studied by fluorescence microscopy. Two sets of split reporters have been developed: the original one allows one to measure fusion kinetics over hours whereas the more recent version was designed to enhance the sensitivity of RL activity allowing one to monitor both initiation and rates of fusion in minutes. Here, we provide a detailed, step-by-step protocol for the optimization of the assay (which we call the SLA for split luciferase assay) using the HSV system. We also show several examples of the power of this assay to examine both the initiation and kinetics of cell-cell fusion by wild type forms of gD, gB, gH/gL of both serotypes of HSV as well as the effect of mutations and antibodies that alter the kinetics of fusion. The SLA can be applied to other viral systems that carry out membrane fusion. (C) 2015 Elsevier Inc. All rights reserved.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
Ma, Teng
Liu, Hao
Sun, Xianlei
Gao, Liquan
Shi, Jiyun
Zhao, Huiyun
Jia, Bing
Wan, Fan
Liu, Zhaofei
Ma, Teng
Liu, Hao
Sun, Xianlei
Gao, Liquan
Jia, Bing
Wan, Fan
Liu, Zhaofei
Shi, Jiyun
Zhao, Huiyun
摘要： Cetuximab is an antiepidermal growth factor receptor (EGFR) monoclonal antibody that has received the approval of the Food and Drug Administration (FDA) for cancer treatment. However, most clinical studies indicate that cetuximab can only elicit positive effects on a subset of cancer patients. In this study, we investigated whether near-infrared fluorescence (NIRF) imaging of tumor vascular endothelial growth factor (VEGF) expression could be a biomarker for tumor early response to cetuximab therapy in preclinical wild-type and mutant tumor models of the KRAS gene. The treatment efficacy of cetuximab was determined in both HT-29 (wild-type KRAS) and HTC-116 (mutant KRAS) human colon cancer models. A VEGF-specific optical imaging probe (Dye755-Ran) was synthesized by conjugating ranibizumab (an anti-VEGF antibody Fab fragment) with a NIRF dye. Serial optical scans with Dye755-Ran were performed in HT-29 and HTC-116 xenograft models. By using longitudinal NIRF imaging, we were able to detect early tumor response on day 3 and day 5 after initiation of cetuximab treatment in the cetuximab-responsive HT-29 tumor model. Enzyme-linked immunosorbent assay (ELISA) confirmed that cetuximab treatment inhibited human VEGF expression in the KRAS wild-type HT-29 tumor but not in the KRAS mutant HCT-116 tumor. We have demonstrated that the antitumor effect of cetuximab can be noninvasively monitored by serial fluorescence imaging using Dye755-Ran. VEGF expression detected by optical imaging could serve as a sensitive biomarker for tumor early response to drugs that directly or indirectly act on VEGF.
分类： 生物学 >> 生物医药 提交时间： 2017-03-30
摘要： Lung cancer is one of the leading causes of death with one of the lowest survival rates. However, a subset of lung cancer patients who are of Asian origin and carry somatic mutations in epidermal growth factor receptor or EGFR have responded remarkable well to two tyrosine kinase inhibitors, gefitinib and erlotinib. While EGFR mutation profiles have been reported from Japan, South Korea, and Taiwan, there is no such report from mainland of China where the largest pool of patients reside. In this report, we identified ten somatic mutations from a total of 41 lung cancer patients in China. Among them, seven mutations were found in 17 adenocarcinomas. In contrast to previous reports, eight of these mutations are deletions in exon 19 and two of these deletions are homozygous. These results suggest that a large portion of Chinese adenocarcinoma patients could benefit from gefitinib or erlotinib. This unique mutation profile provides a rationale to develop the next generation of EGFR inhibitors more suitable for the Chinese population.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Yang, Fan
Li, Fa-Hui
Wang, Jiang-Yun
Yang, Fan
Li, Fa-Hui
Wang, Jiang-Yun
Yang, Fan
Yu, Xiao
Liu, Chuan
Qu, Chang-Xiu
Gong, Zheng
Liu, Hong-Da
He, Dong-Fang
Sun, Jin-Peng
Yang, Fan
Yu, Xiao
Liu, Chuan
Qu, Chang-Xiu
Gong, Zheng
Liu, Hong-Da
摘要： Specific arrestin conformations are coupled to distinct downstream effectors, which underlie the functions of many G-protein-coupled receptors (GPCRs). Here, using unnatural amino acid incorporation and fluorine-19 nuclear magnetic resonance (F-19-NMR) spectroscopy, we demonstrate that distinct receptor phospho-barcodes are translated to specific beta-arrestin-1 conformations and direct selective signalling. With its phosphate-binding concave surface, b-arrestin-1 'reads' the message in the receptor phospho-C-tails and distinct phospho-interaction patterns are revealed by F-19-NMR. Whereas all functional phosphopeptides interact with a common phosphate binding site and induce the movements of finger and middle loops, different phospho-interaction patterns induce distinct structural states of b-arrestin-1 that are coupled to distinct arrestin functions. Only clathrin recognizes and stabilizes GRK2-specific b-arrestin-1 conformations. The identified receptor-phosphoselective mechanism for arrestin conformation and the spacing of the multiple phosphatebinding sites in the arrestin enable arrestin to recognize plethora phosphorylation states of numerous GPCRs, contributing to the functional diversity of receptors.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
Wang, Xiangxi
Gao, Qiang
Sun, Yao
Li, Xuemei
Rao, Zihe
Ren, Jingshan
Stuart, David I.
Fry, Elizabeth E.
Gao, Qiang
Yin, Weidong
Hu, Zhongyu
Wang, Junzhi
Rowlands, David J.
Rowlands, David J.
Stuart, David I.
Rao, Zihe
Rao, Zihe
摘要： Hepatitis A virus(HAV) remains enigmatic, despite 1.4 million cases worldwide annually(1). It differs radically from other picornaviruses, existing in an enveloped form(2) and being unusually stable, both genetically and physically(3), but has proved difficult to study. Here we report high-resolution X-ray structures for the mature virus and the empty particle. The structures of the two particles are indistinguishable, apart from some disorder on the inside of the empty particle. The full virus contains the small viral protein VP4, whereas the empty particle harbours only the uncleaved precursor, VP0. The smooth particle surface is devoid of depressions that might correspond to receptor-binding sites. Peptide scanning data extend the previously reported VP3 antigenic site4, while structure-based predictions(5) suggest further epitopes. HAV contains no pocket factor and can withstand remarkably high temperature and low pH, and empty particles are even more robust than full particles. The virus probably uncoats via a novel mechanism, being assembled differently to other picornaviruses. It utilizes a VP2 'domain swap' characteristic of insect picorna-like viruses(6,7), and structure-based phylogenetic analysis places HAV between typical picornaviruses and the insect viruses. The enigmatic properties of HAV may reflect its position as a link between 'modern' picornaviruses and the more 'primitive' precursor insect viruses; for instance, HAV retains the ability to move from cell-to-cell by transcytosis(8,9).
分类： 生物学 >> 生物物理学 >> 免疫学 提交时间： 2016-05-12
摘要： We previously showed that LIGHT and its receptor herpes virus entry mediator (HVEM) are important for development of optimal CD4(+) Th1 cell immunity and resistance to primary Leishmania major infection in mice. In this study, we further characterized the contributions of this molecule in dendritic cell (DC) maturation, initiation, and maintenance of primary immunity and secondary anti-Leishmania immunity. Flow-cytometric studies showed that CD8 alpha(+) DC subset was mostly affected by HVEM-Ig and lymphotoxin beta receptor-Ig treatment. LIGHT signaling is required at both the priming and the maintenance stages of primary anti-Leishmania immunity but is completely dispensable during secondary immunity in wild type mice. However, LIGHT blockade led to impaired IL-12 and IFN-gamma responses and loss of resistance in healed CD40-deficient mice after L. major challenge. The protective effect of LIGHT was mediated primarily via its interaction with lymphotoxin beta receptor on CD8 alpha(+) DCs. Collectively, our results show that although LIGHT is critical for maintenance of primary Th1 response, it is dispensable during secondary anti-Leishmania immunity in the presence of functional CD40 signaling as seen in wild type mice.
分类： 生物学 >> 神经生物学 提交时间： 2017-07-24
摘要： Although depression-induced altered pain perception has been described in several laboratory and clinical studies, its neurobiological mechanism in the central nervous system, particularly in the spinal dorsal horn remains unclear. In this study, we therefore aimed to clarify whether nociceptive sensitivity of neuropathic pain is altered in the olfactory bulbectomy (OB) model of depression and whether glucocorticoid receptor (GR), which is involved in the etio-pathologic mechanisms of both major depression and neuropathic pain, contributes to these processes in the spinal dorsal horn of male Sprague-Dawley rats. The results showed that mechanical allodynia and thermal hyperalgesia induced by spinal nerve ligation (SNL) were attenuated in OB-SNL rats with decreased spinal GR expression and nuclear translocation, while NOB (non-olfactory bulbectomy)-SNL rats showed an increased spinal GR nuclear translocation. Decreased GR nuclear translocation with normal mechanical nociception and hypoalgesia of thermal nociception were observed in OB-Sham rats, too. Intrathecal injection of GR agonist dexamethasone (4 µg / rat / day for 1 week) eliminated the attenuating effect of depression on the nociceptive hypersensitivity in OB-SNL rats and aggravated neuropathic pain in NOB-SNL rats, associating with the up-regulation of BDNF, TrkB and NR2B expression in the spinal dorsal horn. The present study shows that depression attenuates the mechanical allodynia and thermal hyperalgesia of neuropathic pain and suggests that altered spinal GR-BDNF-TrkB signaling may be one of the reasons for depression-induced hypoalgesia.
分类： 生物学 >> 神经生物学 提交时间： 2017-03-31
摘要： Although depression-induced altered pain perception has been described in several laboratory and clinical studies, its neurobiological mechanism in the central nervous system, particularly in the spinal dorsal horn remains unclear. In this study, we therefore aimed to clarify whether nociceptive sensitivity of neuropathic pain is altered in the olfactory bulbectomy (OB) model of depression and whether glucocorticoid receptor (GR), which is involved in the etio-pathologic mechanisms of both major depression and neuropathic pain, contributes to these processes in the spinal dorsal horn of male Sprague-Dawley rats. The results showed that mechanical allodynia and thermal hyperalgesia induced by spinal nerve ligation (SNL) were attenuated in OB-SNL rats with decreased spinal GR expression and nuclear translocation, while NOB (non-olfactory bulbectomy)-SNL rats showed an increased spinal GR nuclear translocation. Decreased GR nuclear translocation with normal mechanical nociception and hypoalgesia of thermal nociception were observed in OB-Sham rats, too. Intrathecal injection of GR agonist dexamethasone (4 µg / rat / day for 1 week) eliminated the attenuating effect of depression on the nociceptive hypersensitivity in OB-SNL rats and aggravated neuropathic pain in NOB-SNL rats, associating with the up-regulation of BDNF, TrkB and NR2B expression in the spinal dorsal horn. The present study shows that depression attenuates the mechanical allodynia and thermal hyperalgesia of neuropathic pain and suggests that altered spinal GR-BDNF-TrkB signaling may be one of the reasons for depression-induced hypoalgesia.
分类： 医学、药学 >> 基础医学 提交时间： 2021-01-07
摘要： Objective: Therapeutic tumor vaccines are eagerly awaited in clinic by patients with high expectations; however, very few clinically successful tumor vaccine has been developed thus far, and there remains no consensus on the generation of tumor vaccines. We hypothesized that targeted delivery of pan-tumor antigens instead of individual tumor-associated antigen (TAA) to dendritic cells via the activating receptor endocytic pathway (AREP) would provide an alternative avenue to develop potent personalized tumor vaccines. Methods: We first prepared biotin-tagged tumor antigens (B-TAgs) with mouse CT26. WT colorectal cancer cells by exploiting metabolic glycan labeling and bioorthogonal reaction methods; then, we prepared a bifunctional fusion protein containing streptavidin and a mouse IgG2a Fc fragment (SA-Fc), in which streptavidin was used for conjugation with B-TAgs, and Fc for mediating the interaction with the Fcγ receptor. Finally, conjugates (Fc-TAgs) of SA-Fc with B-TAgs were prepared based on affinity-guided noncovalent reaction. The phenotype of Fc-TAgs pulsed bone marrow-derived dendritic cells (BMDCs) was examined by flow cytometry. The therapeutic effects of Fc-TAgs pulsed BMDCs were observed in an established mouse CT26. WT colorectal cancer model. Results: The prepared B-TAgs covers almost all glycosylated tumor antigens. SA-Fc fusion protein exhibits biotin-binding activity as a homodimer. SA-Fc can effectively conjugate with B-TAg at a mixing ratio of 1:96 (w/w). Data of flow cytometry revealed that on Fc-TAgs pulsed BMDCs, the expression levels of surface molecules, such as CD80 and MHC II, were greatly increased. In the established murine colorectal cancer model, combination treatments with Fc-TAgs pulsed BMDCs and PD-1 blockade achieved significant therapeutic effects. Limitations: The strategy we proposed for the preparation of personalized tumor vaccine requires that the tumor be surgically removed from the patient. The rationality and validity of this strategy need to be proven by more preclinical investigations. Conclusions: The novel strategy we proposed circumvents the necessities for neoantigen prediction and provides an alternative pathway to establish a flexible system for the preparation of personalized dendritic cell tumor vaccines. In the setting of checkpoint blockade-based immunotherapy, a novel DCV would improve antitumor immunity and benefit the eradication of tumor residues within the body of the cancer patients.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Shu, Qingbo
Cai, Tanxi
Chen, Xiulan
Xue, Peng
Zhu, Nali
Xie, Zhensheng
Wei, Shasha
Niu, Lili
Yang, Fuquan
Shu, Qingbo
Cai, Tanxi
Chen, Xiulan
Xue, Peng
Zhu, Nali
Xie, Zhensheng
Wei, Shasha
Niu, Lili
Yang, Fuquan
Shu, Qingbo
Zhang, Qing
摘要： One of the major challenges in prostate cancer therapy remains the development of effective treatments for castration-resistant prostate cancer (CRPC), as the underlying mechanisms for its progression remain elusive. Previous studies showed that androgen receptor (AR) is crucially involved in regulation of metabolism in prostate cancer (PCa) cells throughout the transition from early stage, androgen-sensitive PCa to androgen-independent CRPC. AR achieves such metabolic rewiring directively either via its transcriptional activity or via interactions with AMP-activated protein kinase (AMPK). However, due to the heterogeneous expression and activity status of AR in PCa cells, it remains a challenge to investigate the links between AR status and metabolic alterations. To this end, we compared the proteomes of three pairs of androgen-sensitive (AS) and androgen-independent (AI) PCa cell lines, namely, PC3-AR(+)/PC3, 22Rv1/Du145, and LNCaP/C42B, using an iTRAQ labeling approach. Our results revealed that most of the differentially expressed proteins between each pair function in metabolism, indicating a metabolic shift between AS and AT cells, as further validated by multiple reaction monitoring (MRM)-based quantification of nucleotides and relative comparison of fatty acids between these cell lines. Furthermore, increased adenylate kinase isoenzyme 1 (AK1) in AS relative to AT cells may result in activation of AMPK, representing a major regulatory factor involved in the observed metabolic shift in PCa cells.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
摘要： Humidity is one of the most important factors that determines the geographical distribution and survival of terrestrial animals. The ability to detect variation in humidity is conserved across many species. Here, we established a novel behavioral assay that revealed the thirsty Drosophila exhibits strong hygrotactic behavior, and it can locate water by detecting humidity gradient. In addition, exposure to high levels of moisture was sufficient to elicit proboscis extension reflex behavior in thirsty flies. Furthermore, we found that the third antennal segment was necessary for hygrotactic behavior in thirsty flies, while arista was required for the avoidance of moist air in hydrated flies. These results indicated that two types of hygroreceptor cells exist in Drosophila: one located in the third antennal segment that mediates hygrotactic behavior in thirst status, and the other located in arista which is responsible for the aversive behavior toward moist air in hydration status. Using a neural silencing screen, we demonstrated that synaptic output from the mushroom body alpha/beta surface and posterior neurons was required for both hygrotactic behavior and moisture-aversive behavior.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Sun, Xianlei
Gao, Duo
Gao, Liquan
Zhang, Chenran
Yu, Xinhe
Jia, Bing
Wang, Fan
Liu, Zhaofei
Sun, Xianlei
Gao, Duo
Gao, Liquan
Zhang, Chenran
Yu, Xinhe
Jia, Bing
Wang, Fan
Liu, Zhaofei
Wang, Fan
摘要： Significant evidence has indicated that tumor-associated macrophages (TAMs) play a critical role in the proliferation, invasion, angiogenesis, and metastasis of a variety of human carcinomas. In this study, we investigated whether near-infrared fluorescence (NIRF) imaging using a macrophage mannose receptor (MMR; CD206)-targeting agent could be used to noninvasively visualize and quantify changes in TAMs in vivo. The CD206-targeting NIRF agent, Dye-anti-CD206, was prepared and characterized in vitro and in vivo. By using NIRF imaging, we were able to noninvasively image tumor-infiltrating macrophages in the 4T1 mouse breast cancer model. Importantly, longitudinal NIRF imaging revealed the depletion of macrophages in response to zoledronic acid (ZA) treatment. However, ZA alone did not lead to the inhibition of 4T1 tumor growth. We therefore combined anti-macrophage ZA therapy and tumor cytotoxic docetaxel (DTX) therapy in the mouse model. The results demonstrated that this combination strategy could significantly inhibit tumor growth as well as tumor metastasis to the lungs. Based on these findings, we concluded that CD206-targeted molecular imaging can sensitively detect the dynamic changes in tumor-infiltrating macrophages, and that the combination of macrophage depletion and cytotoxic therapy is a promising strategy for the effective treatment of solid tumors.
分类： 生物学 >> 生物物理学 >> 免疫学 提交时间： 2016-05-11
摘要： Lipopolysaccharide (LPS) is the major component of Gram-negative bacteria cell wall. In innate immunity, extracellular LPS is recognized by Toll-like receptor 4 to stimulate cytokine transcription. Recent studies suggest a 'non-canonical inflammasome' that senses cytoplasmic LPS and activates caspase-11 in mouse macrophages. Unexpectedly, biochemical studies reveal that caspase-11 and its human orthologs caspase-4/caspase-5 are LPS receptors themselves. Direct LPS binding induces caspase-4/caspase-5/caspase-11 oligomerization and activation, triggering cell pyroptosis and anti-bacterial defenses. Caspase-4/caspase-5/caspase-11 recognition of intracellular LPS requires bacterial escape from the vacuole; this process is promoted by interferon-inducible GTPases-mediated lysis of the bacteria-containing vacuole. Non-canonical activation of these inflammatory caspases by LPS not only represents a new paradigm in innate immunity but also critically determines LPS-induced septic shock in mice.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-11
Mi, Zeyun
Ding, Jiwei
Zhang, Quan
Ma, Ling
Shan, Guangzhi
Li, Xiaoyu
Zhou, Jinming
Cen, Shan
Mi, Zeyun
Ding, Jiwei
Zhang, Quan
Ma, Ling
Shan, Guangzhi
Li, Xiaoyu
Zhou, Jinming
Cen, Shan
Zhao, Jianyuan
Wei, Tao
Liu, Zhenlong
Liang, Chen
摘要： Human BST-2 inhibits HIV-1 replication by tethering nascent virions to the cell surface. HIV-1 codes Vpu that counteracts BST-2 by down-regulating this restriction factor from the cell surface. This important function makes Vpu a potential therapeutic target. Yet, no agents have been reported to block Vpu from antagonizing BST-2. In this study, we report a small molecule compound IMB-LA that abrogates the function of Vpu and thereby strongly suppresses HIV-1 replication by sensitizing the virus to BST-2 restriction. Further studies revealed that IMB-LA specifically inhibits Vpu-mediated degradation of BST-2 and restores the expression of BST-2 at the cell surface. Although IMB-LA does not prevent Vpu from interacting with BST-2 or beta-TrCP2-containing ubiquitin E3 ligase, sorting of BST-2 into lysosomes in Vpu-expressing cells is blocked by IMB-LA. Most importantly, HIV-1 release and infection is inhibited by IMB-LA only in BST-2-expressing cells. In summary, results herein demonstrated that IMB-LA could specifically inhibit the degradation of BST-2 induced by Vpu, and impair HIV-1 replication in a BST-2 dependent manner, suggesting the feasibility of utilizing small molecule compounds to disable the antagonist function of Vpu and thereby expose HIV-1 to the restriction by BST-2.
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