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991.
Jing Zhang Yang Zhou Lin Ma Shunquan Huang Ruijin Wang Rongrong Gao Youjun Wu Hongjun Shi Jun Zhang 《Biological trace element research》2013,152(2):267-274
Nickel is an important kind of metal and a necessary trace element in people’s production and livelihood; it is also a well-confirmed human carcinogen. In the past few years, researchers did a large number of studies about the molecular mechanisms of nickel carcinogenesis, and they focused on activation of proto-oncogenes and inactivation of anti-oncogenes caused by gene point mutation, gene deletion, gene amplification, DNA methylation, chromosome condensation, and so on that were induced by nickel. However, the researches on tumorigenic molecular mechanisms regulated by microRNAs (miRNAs) are rare. In this study, we established nickel-induced tumor by injecting Ni3S2 compounds to Wistar Rattus. By establishing a cDNA library of miRNA from rat muscle tumor tissue induced by Ni3S2, we found that the expression of miR-222 was significantly upregulated in tumor tissue compared with the normal tissue. As we expected, the expression levels of target genes of miR-222, CDKN1B and CDKN1C, were downregulated in the nickel-induced tumor. The same alteration of miR-222 and its target genes was also found in malignant 16HBE cells induced with Ni3S2 compounds. We conclude that miR-222 may promote cell proliferation infinitely during nickel-induced tumorigenesis in part by regulating the expression of its target genes CDKN1B and CDKN1C. Our study elucidated a novel molecular mechanism of nickel-induced tumorigenesis. 相似文献
992.
Kevin A. Lawson Colin J. Teteak Junhui Zou Jacques Hacquebord Andrew Ghatan Anna Zielinska-Kwiatkowska Russell J. Fernandes Howard A. Chansky Liu Yang 《The Journal of biological chemistry》2013,288(45):32119-32125
The exact molecular mechanisms governing articular chondrocytes remain unknown in skeletal biology. In this study, we have found that ESET (an ERG-associated protein with a SET domain, also called SETDB1) histone methyltransferase is expressed in articular cartilage. To test whether ESET regulates articular chondrocytes, we carried out mesenchyme-specific deletion of the ESET gene in mice. ESET knock-out did not affect generation of articular chondrocytes during embryonic development. Two weeks after birth, there was minimal qualitative difference at the knee joints between wild-type and ESET knock-out animals. At 1 month, ectopic hypertrophy, proliferation, and apoptosis of articular chondrocytes were seen in the articular cartilage of ESET-null animals. At 3 months, additional signs of terminal differentiation such as increased alkaline phosphatase activity and an elevated level of matrix metalloproteinase (MMP)-13 were found in ESET-null cartilage. Staining for type II collagen and proteoglycan revealed that cartilage degeneration became progressively worse from 2 weeks to 12 months at the knee joints of ESET knock-out mutants. Analysis of over 14 pairs of age- and sex-matched wild-type and knock-out mice indicated that the articular chondrocyte phenotype in ESET-null mutants is 100% penetrant. Our results demonstrate that expression of ESET plays an essential role in the maintenance of articular cartilage by preventing articular chondrocytes from terminal differentiation and may have implications in joint diseases such as osteoarthritis. 相似文献
993.
Tyler Schwend Zhigang Jin Kai Jiang Brian J. Mitchell Jianhang Jia Jing Yang 《The Journal of biological chemistry》2013,288(45):32809-32820
994.
Wei-Chien Hung Shih-Hsun Chen Colin D. Paul Kimberly M. Stroka Ying-Chun Lo Joy T. Yang Konstantinos Konstantopoulos 《The Journal of cell biology》2013,202(5):807-824
Using a microchannel assay, we demonstrate that cells adopt distinct signaling strategies to modulate cell migration in different physical microenvironments. We studied α4β1 integrin–mediated signaling, which regulates cell migration pertinent to embryonic development, leukocyte trafficking, and melanoma invasion. We show that α4β1 integrin promotes cell migration through both unconfined and confined spaces. However, unlike unconfined (2D) migration, which depends on enhanced Rac1 activity achieved by preventing α4/paxillin binding, confined migration requires myosin II–driven contractility, which is increased when Rac1 is inhibited by α4/paxillin binding. This Rac1–myosin II cross talk mechanism also controls migration of fibroblast-like cells lacking α4β1 integrin, in which Rac1 and myosin II modulate unconfined and confined migration, respectively. We further demonstrate the distinct roles of myosin II isoforms, MIIA and MIIB, which are primarily required for confined and unconfined migration, respectively. This work provides a paradigm for the plasticity of cells migrating through different physical microenvironments. 相似文献
995.
Ziguo Zhang Leifu ChangJing Yang Nora ConinKiran Kulkarni David Barford 《Journal of molecular biology》2013
The anaphase-promoting complex or cyclosome (APC/C) is a large E3 RING-cullin ubiquitin ligase composed of between 14 and 15 individual proteins. A striking feature of the APC/C is that only four proteins are involved in directly recognizing target proteins and catalyzing the assembly of a polyubiquitin chain. All other subunits, which account for > 80% of the mass of the APC/C, provide scaffolding functions. A major proportion of these scaffolding subunits are structurally related. In metazoans, there are four canonical tetratricopeptide repeat (TPR) proteins that form homo-dimers (Apc3/Cdc27, Apc6/Cdc16, Apc7 and Apc8/Cdc23). Here, we describe the crystal structure of the N-terminal homo-dimerization domain of Schizosaccharomyces pombe Cdc23 (Cdc23Nterm). Cdc23Nterm is composed of seven contiguous TPR motifs that self-associate through a related mechanism to those of Cdc16 and Cdc27. Using the Cdc23Nterm structure, we generated a model of full-length Cdc23. The resultant “V”-shaped molecule docks into the Cdc23-assigned density of the human APC/C structure determined using negative stain electron microscopy (EM). Based on sequence conservation, we propose that Apc7 forms a homo-dimeric structure equivalent to those of Cdc16, Cdc23 and Cdc27. The model is consistent with the Apc7-assigned density of the human APC/C EM structure. The four canonical homo-dimeric TPR proteins of human APC/C stack in parallel on one side of the complex. Remarkably, the uniform relative packing of neighboring TPR proteins generates a novel left-handed suprahelical TPR assembly. This finding has implications for understanding the assembly of other TPR-containing multimeric complexes. 相似文献
996.
Van Anthony M. Villar John Edward Jones Ines Armando Laureano D. Asico Crisanto S. Escano Jr. Hewang Lee Xiaoyan Wang Yu Yang Annabelle M. Pascua-Crusan Cynthia P. Palmes-Saloma Robin A. Felder Pedro A. Jose 《The Journal of biological chemistry》2013,288(1):152-163
The peripheral dopaminergic system plays a crucial role in blood pressure regulation through its actions on renal hemodynamics and epithelial ion transport. The dopamine D5 receptor (D5R) interacts with sorting nexin 1 (SNX1), a protein involved in receptor retrieval from the trans-Golgi network. In this report, we elucidated the spatial, temporal, and functional significance of this interaction in human renal proximal tubule cells and HEK293 cells stably expressing human D5R and in mice. Silencing of SNX1 expression via RNAi resulted in the failure of D5R to internalize and bind GTP, blunting of the agonist-induced increase in cAMP production and decrease in sodium transport, and up-regulation of angiotensin II receptor expression, of which expression was previously shown to be negatively regulated by D5R. Moreover, siRNA-mediated depletion of renal SNX1 in C57BL/6J and BALB/cJ mice resulted in increased blood pressure and blunted natriuretic response to agonist in salt-loaded BALB/cJ mice. These data demonstrate a crucial role for SNX1 in D5R trafficking and that SNX1 depletion results in D5R dysfunction and thus may represent a novel mechanism for the pathogenesis of essential hypertension. 相似文献
997.
Jingjing Ben Yan Zhang Rongmei Zhou Haiyang Zhang Xudong Zhu Xiaoyu Li Hanwen Zhang Nan Li Xiaodan Zhou Hui Bai Qing Yang Donghai Li Yong Xu Qi Chen 《The Journal of biological chemistry》2013,288(27):20076-20084
Atherosclerosis is considered a disease of chronic inflammation largely initiated and perpetuated by macrophage-dependent synthesis and release of pro-inflammatory mediators. Class A scavenger receptor (SR-A) expressed on macrophages plays a key role in this process. However, how SR-A-mediated pro-inflammatory response is modulated in macrophages remains ill defined. Here through immunoprecipitation coupled with mass spectrometry, we reported major vault protein (MVP) as a novel binding partner for SR-A. The interaction between SR-A and MVP was confirmed by immunofluorescence staining and chemical cross-linking assay. Treatment of macrophages with fucoidan, a SR-A ligand, led to a marked increase in TNF-α production, which was attenuated by MVP depletion. Further analysis revealed that SR-A stimulated TNF-α synthesis in macrophages via the caveolin- instead of clathrin-mediated endocytic pathway linked to p38 and JNK, but not ERK, signaling pathways. Importantly, fucoidan invoked an enrichment of MVP in lipid raft, a caveolin-reliant membrane structure, and enhanced the interaction among SR-A, caveolin, and MVP. Finally, we demonstrated that MVP elimination ameliorated SR-A-mediated apoptosis in macrophages. As such, MVP may fine-tune SR-A activity in macrophages which contributes to the development of atherosclerosis. 相似文献
998.
Xiaolin Hu Kankana Bardhan Amy V. Paschall Dafeng Yang Jennifer L. Waller Mary Anne Park Asha Nayak-Kapoor Thomas A. Samuel Scott I. Abrams Kebin Liu 《The Journal of biological chemistry》2013,288(26):19103-19115
Myeloid-derived suppressor cells (MDSCs) are heterogeneous immature myeloid cells that accumulate in response to tumor progression. Compelling data from mouse models and human cancer patients showed that tumor-induced inflammatory mediators induce MDSC differentiation. However, the mechanisms underlying MDSC persistence is largely unknown. Here, we demonstrated that tumor-induced MDSCs exhibit significantly decreased spontaneous apoptosis as compared with myeloid cells with the same phenotypes from tumor-free mice. Consistent with the decreased apoptosis, cell surface Fas receptor decreased significantly in tumor-induced MDSCs. Screening for changes of key apoptosis mediators downstream the Fas receptor revealed that expression levels of IRF8 and Bax are diminished, whereas expression of Bcl-xL is increased in tumor-induced MDSCs. We further determined that IRF8 binds directly to Bax and Bcl-x promoter in primary myeloid cells in vivo, and IRF8-deficient MDSC-like cells also exhibit increased Bcl-xL and decreased Bax expression. Analysis of CD69 and CD25 levels revealed that cytotoxic T lymphocytes (CTLs) are partially activated in tumor-bearing hosts. Strikingly, FasL but not perforin and granzymes were selectively activated in CTLs in the tumor-bearing host. ABT-737 significantly increased the sensitivity of MDSCs to Fas-mediated apoptosis in vitro. More importantly, ABT-737 therapy increased MDSC spontaneous apoptosis and decreased MDSC accumulation in tumor-bearing mice. Our data thus determined that MDSCs use down-regulation of IRF8 to alter Bax and Bcl-xL expression to deregulate the Fas-mediated apoptosis pathway to evade elimination by host CTLs. Therefore, targeting Bcl-xL is potentially effective in suppression of MDSC persistence in cancer therapy. 相似文献
999.
1000.
Shuai Liu Hui Yang Jian Zhao Yu-Hang Zhang Ai-Xin Song Hong-Yu Hu 《The Journal of biological chemistry》2013,288(43):31339-31349
The NEDD8 protein and neddylation levels in cells are modulated by NUB1L or NUB1 through proteasomal degradation, but the underlying molecular mechanism is not well understood. Here, we report that NUB1L down-regulated the protein levels of NEDD8 and neddylation through specifically recognizing NEDD8 and P97/VCP. NUB1L directly interacted with NEDD8, but not with ubiquitin, on the key residue Asn-51 of NEDD8 and with P97/VCP on its positively charged VCP binding motif. In coordination with the P97-UFD1-NPL4 complex (P97UFD1/NPL4), NUB1L promotes transfer of NEDD8 to proteasome for degradation. This mechanism is also exemplified by the canonical neddylation of cullin 1 for SCF (SKP1-cullin1-F-box) ubiquitin E3 ligases that is exquisitely regulated by the turnover of NEDD8. 相似文献