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961.
Recent studies have shown that transforming growth factor (TGF)-beta3 regulates blood-testis barrier (BTB) dynamics in vivo, plausibly by determining the steady-state levels of occludin and zonula occludens-1 (ZO-1) at the BTB site via the p38 MAP kinase signaling pathway. Since BTB is composed of coexisting TJs and basal ectoplasmic specializations [ES, a testis-specific adherens junction (AJ) type] in the seminiferous epithelium of the rat testis, we sought to examine if TGF-beta3 would also regulate anchoring junction dynamics. Using an in vivo model in which rats were treated with AF-2364 [1-(2,4-dichlorobenzyl)-indazole-3-carbohydrazide] to perturb Sertoli-germ cell AJs without affecting the integrity of TJs at the BTB, it was noted that the event of germ cell loss from the epithelium was associated with a transient surge in TGF-beta3. Furthermore, it was also associated with a surge in the protein levels of Ras, p-ERK, and the intrinsic activity of ERK, illustrating TGF-beta3 apparently regulates Sertoli-germ cell ES function via the Ras/MEK/ERK signaling pathway. Indeed, pretreatment of rats with TbetaRII/Fc chimera, a TGF-beta antagonist, or U0126, a specific MEK inhibitor, could significantly delay and partially block the disruptive effects of AF-2364 in depleting germ cells from the epithelium. While the protein levels of the cadherin/catenin complex were significantly induced during AF-2364-mediated germ cell loss, perhaps being used to retain germ cells in the epithelium, this increase failed to reverse the loss of adhesion function between Sertoli and germ cells because of a loss of protein-protein interactions between cadherins and catenins. Collectively, these results illustrate that the testis has a novel mechanism in place in which an agent that primarily disrupts TJs can induce secondary loss of AJ function, leading to germ cell loss from the seminiferous epithelium. Yet an agent that selectively disrupts AJs (e.g., AF-2364) can limit its effects exclusively at the Sertoli-germ cell adhesive site without perturbing the Sertoli-Sertoli TJs. 相似文献
962.
Li L Wang X Xia M Stolc V Su N Peng Z;Waraporn Tongprasit Li S Wang J Wang X Deng XW 《Genome biology》2005,6(6):R52
Background
Sequencing and annotation of the genome of rice (Oryza sativa) have generated gene models in numbers that top all other fully sequenced species, with many lacking recognizable sequence homology to known genes. Experimental evaluation of these gene models and identification of new models will facilitate rice genome annotation and the application of this knowledge to other more complex cereal genomes. 相似文献963.
An Arabidopsis aspartic protease functions as an anti-cell-death component in reproduction and embryogenesis 总被引:1,自引:0,他引:1
The components and pathways that regulate and execute developmental cell death programmes in plants remain largely unknown. We have found that the PROMOTION OF CELL SURVIVAL 1 (PCS1) gene in Arabidopsis, which encodes an aspartic protease, has an important role in determining the fate of cells in embryonic development and in reproduction processes. The loss-of-function mutation of PCS1 causes degeneration of both male and female gametophytes and excessive cell death of developing embryos. Conversely, ectopic expression of PCS1 causes the septum and stomium cells that normally die in the anther wall to survive instead, leading to a failure in anther dehiscence and male sterility. PCS1 provides a new avenue for understanding the mechanisms of the programmed cell death processes that are associated with developmental pathways in plants and makes available a useful tool for engineering the male sterility trait for hybrid seed production. 相似文献
964.
Zheng Guo Tianwen Zhang Xia Li Qi Wang Jianzhen Xu Hui Yu Jing Zhu Haiyun Wang Chenguang Wang Eric J Topol Qing Wang Shaoqi Rao 《BMC bioinformatics》2005,6(1):1-12
Background
Despite the continuous production of genome sequence for a number of organisms, reliable, comprehensive, and cost effective gene prediction remains problematic. This is particularly true for genomes for which there is not a large collection of known gene sequences, such as the recently published chicken genome. We used the chicken sequence to test comparative and homology-based gene-finding methods followed by experimental validation as an effective genome annotation method.Results
We performed experimental evaluation by RT-PCR of three different computational gene finders, Ensembl, SGP2 and TWINSCAN, applied to the chicken genome. A Venn diagram was computed and each component of it was evaluated. The results showed that de novo comparative methods can identify up to about 700 chicken genes with no previous evidence of expression, and can correctly extend about 40% of homology-based predictions at the 5' end.Conclusions
De novo comparative gene prediction followed by experimental verification is effective at enhancing the annotation of the newly sequenced genomes provided by standard homology-based methods. 相似文献965.
Background
MATLAB is a high-performance language for technical computing, integrating computation, visualization, and programming in an easy-to-use environment. It has been widely used in many areas, such as mathematics and computation, algorithm development, data acquisition, modeling, simulation, and scientific and engineering graphics. However, few functions are freely available in MATLAB to perform the sequence data analyses specifically required for molecular biology and evolution. 相似文献966.
Lisa?L?Maduzia Andrew?F?Roberts Huang?Wang Xia?Lin Lena?J?Chin Cole?M?Zimmerman Stephen?Cohen Xin-Hua?Feng Richard?W?PadgettEmail author 《BMC developmental biology》2005,5(1):8
Background
In C. elegans there are two well-defined TGFβ-like signaling pathways. The Sma/Mab pathway affects body size morphogenesis, male tail development and spicule formation while the Daf pathway regulates entry into and exit out of the dauer state. To identify additional factors that modulate TGFβ signaling in the Sma/Mab pathway, we have undertaken a genetic screen for small animals and have identified kin-29. 相似文献967.
Jiang XS Tang LY Dai J Zhou H Li SJ Xia QC Wu JR Zeng R 《Molecular & cellular proteomics : MCP》2005,4(7):902-913
We present the first proteomic analysis on the cellular response to severe acute respiratory syndrome-associated coronavirus (SARS-CoV) infection. The differential proteomes of Vero E6 cells with and without infection of the SARS-CoV were resolved and quantitated with two-dimensional differential gel electrophoresis followed by ESI-MS/MS identification. Moreover isotope-coded affinity tag technology coupled with two-dimensional LC-MS/MS were also applied to the differential proteins of infected cells. By combining these two complementary strategies, 355 unique proteins were identified and quantitated with 186 of them differentially expressed (at least 1.5-fold quantitative alteration) between infected and uninfected Vero E6 cells. The implication for cellular responses to virus infection was analyzed in depth according to the proteomic results. Thus, the present work provides large scale protein-related information to investigate the mechanism of SARS-CoV infection and pathogenesis. 相似文献
968.
Proteomic analysis of hepatitis B virus-associated hepatocellular carcinoma: Identification of potential tumor markers 总被引:12,自引:0,他引:12
Li C Tan YX Zhou H Ding SJ Li SJ Ma DJ Man XB Hong Y Zhang L Li L Xia QC Wu JR Wang HY Zeng R 《Proteomics》2005,5(4):1125-1139
Hepatocellular carcinoma (HCC) is a malignancy of both underdeveloped and developing countries. Proteomes of ten pairs of clinical hepatitis B virus associated HCC tissue samples were obtained by high resolution two-dimensional gel electrophoresis. Comprehensive analyses of proteins associated with B-type HCC were focused on total differentially expressed proteins (> or = two-fold increase or decrease, Student's t-test, p < 0.05) from one pair of samples. Protein identification was done by peptide mass fingerprinting with matrix assisted laser desorption/ionization-time of flight mass spectrometry and liquid chromatography-tandem mass spectrometry. Comparative analyses of proteins associated with B-type HCC included repeat statistics in ten cases. A total of 100 protein spots, corresponding to 80 different gene products, were identified. Proteins whose expression levels were different by more than 2-fold in at least 50% of the cases (five of ten cases) were further analyzed and 45 proteins were selected out as candidates for HCC-associated proteins. Western blotting further validated up-regulated expressions of two candidate proteins in tumor tissues: proliferating cell antigen and stathmin 1. This comprehensive and comparative analyses of proteins associated with B-type HCC could provide useful molecular markers for diagnostics and prognostics and for therapeutic targets. The physiological significance of the differential expressions for several candidate proteins are discussed. 相似文献
969.
Nho RS Xia H Kahm J Kleidon J Diebold D Henke CA 《The Journal of biological chemistry》2005,280(28):26630-26639
A beta1 integrin phosphatidylinositol 3-kinase/Akt pathway regulates fibroblast survival in collagen matrices. When fibroblasts attach to collagen, Akt becomes phosphorylated, providing a survival signal. In contrast, in response to mechanical forces generated during collagen contraction, Akt is dephosphorylated and fibroblasts undergo apoptosis. The kinase(s) responsible for regulating Akt phosphorylation in response to matrix-derived mechanical signals are unclear. Integrin-linked kinase (ILK) is associated with the beta1 integrin in the focal adhesion complex and as such is a candidate kinase that may regulate Akt phosphorylation and fibroblast viability. Nevertheless, there is no direct evidence that matrix-derived mechanical forces regulate cell viability by modulating ILK activity. Here, we show that ILK activity decreased in response to collagen matrix contraction, which correlated with Akt dephosphorylation and induction of fibroblast apoptosis. In contrast, enforced activation of beta1 integrin by activating antibody preserved ILK and Akt activity during collagen matrix contraction, and this is associated with protection from collagen contraction-induced apoptosis. Knock-down of ILK by small, interfering RNA (siRNA) attenuated Akt phosphorylation in response to ligation of beta1 integrin by collagen or activating antibody and enhanced fibroblast apoptosis in response to collagen contraction. Kinase dead ILK attenuated Akt phosphorylation and enhanced fibroblast apoptosis, whereas hyperactive and wild type ILK augmented Akt phosphorylation and protected fibroblasts from apoptosis. Constitutively active Akt preserved Akt activity and rescued ILK siRNA-treated fibroblasts from collagen contraction-induced apoptosis. These data establish that matrix-derived mechanical forces sensed by beta1 integrin are capable of modulating ILK activity which regulates fibroblast viability via an Akt-dependent mechanism. 相似文献
970.