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301.
302.
A novel cell response triggered by interphase centromere structural instability 总被引:3,自引:0,他引:3 下载免费PDF全文
Interphase centromeres are crucial domains for the proper assembly of kinetochores at the onset of mitosis. However, it is not known whether the centromere structure is under tight control during interphase. This study uses the peculiar property of the infected cell protein 0 of herpes simplex virus type 1 to induce centromeric structural damage, revealing a novel cell response triggered by centromere destabilization. It involves centromeric accumulation of the Cajal body-associated coilin and fibrillarin as well as the survival motor neuron proteins. The response, which we have termed interphase centromere damage response (iCDR), was observed in all tested human and mouse cells, indicative of a conserved mechanism. Knockdown cells for several constitutive centromere proteins have shown that the loss of centromeric protein B provokes the centromeric accumulation of coilin. We propose that the iCDR is part of a novel safeguard mechanism that is dedicated to maintaining interphase centromeres compatible with the correct assembly of kinetochores, microtubule binding, and completion of mitosis. 相似文献
303.
Miguel W. Tregnaghi Xavier Sáez-Llorens Pio López Hector Abate Enrique Smith Adriana Pósleman Arlene Calvo Digna Wong Carlos Cortes-Barbosa Ana Ceballos Marcelo Tregnaghi Alexandra Sierra Mirna Rodriguez Marisol Troiti?o Carlos Carabajal Andrea Falaschi Ana Leandro Maria Mercedes Castrejón Alejandro Lepetic Patricia Lommel William P. Hausdorff Dorota Borys Javier Ruiz Gui?azú Eduardo Ortega-Barría Juan P. Yarzábal Lode Schuerman COMPAS Group 《PLoS medicine》2015,12(6)
304.
Beatriz Vásquez-Soto Nicolás Manríquez Mirna Cruz-Amaya Jan Zouhar Natasha V Raikhel Lorena Norambuena 《Biological research》2015,48(1)
Background
A highly regulated trafficking of cargo vesicles in eukaryotes performs protein delivery to a variety of cellular compartments of endomembrane system. The two main routes, the secretory and the endocytic pathways have pivotal functions in uni- and multi-cellular organisms. Protein delivery and targeting includes cargo recognition, vesicle formation and fusion. Developing new tools to modulate protein trafficking allows better understanding the endomembrane system mechanisms and their regulation. The compound Sortin2 has been described as a protein trafficking modulator affecting targeting of the vacuolar protein carboxypeptidase Y (CPY), triggering its secretion in Saccharomyces cerevisiae.Results
A reverse chemical-genetics approach was used to identify key proteins for Sortin2 bioactivity. A genome-wide Sortin2 resistance screen revealed six yeast deletion mutants that do not secrete CPY when grown at Sortin2 condition where the parental strain does: met18, sla1, clc1, dfg10, dpl1 and yjl175w. Integrating mutant phenotype and gene ontology annotation of the corresponding genes and their interactome pointed towards a high representation of genes involved in the endocytic process. In wild type yeast endocytosis towards the vacuole was faster in presence of Sortin2, which further validates the data of the genome-wide screen. This effect of Sortin2 depends on structural features of the molecule, suggesting compound specificity. Sortin2 did not affect endocytic trafficking in Sortin2-resistant mutants, strongly suggesting that the Sortin2 effects on the secretory and endocytic pathways are linked.Conclusions
Overall, the results reveal that Sortin2 enhances the endocytic transport pathway in Saccharomyces cerevisiae. This cellular effect is most likely at the level where secretory and endocytic pathways are merged. Them Sortin2 specificity over the endomembrane system places it as a powerful biological modulator for cell biology.Electronic supplementary material
The online version of this article (doi:10.1186/s40659-015-0032-9) contains supplementary material, which is available to authorized users. 相似文献305.
306.
To investigate the role of nonreceptor protein tyrosine phosphatase 1B (PTP1B) in β1-integrin– mediated adhesion and signaling, we transfected mouse L cells with normal and catalytically inactive forms of the phosphatase. Parental cells and cells expressing the wild-type or mutant PTP1B were assayed for (a) adhesion, (b) spreading, (c) presence of focal adhesions and stress fibers, and (d) tyrosine phosphorylation. Parental cells and cells expressing wild-type PTP1B show similar morphology, are able to attach and spread on fibronectin, and form focal adhesions and stress fibers. In contrast, cells expressing the inactive PTP1B have a spindle-shaped morphology, reduced adhesion and spreading on fibronectin, and almost a complete absence of focal adhesions and stress fibers. Attachment to fibronectin induces tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin in parental cells and cells transfected with the wild-type PTP1B, while in cells transfected with the mutant PTP1B, such induction is not observed. Additionally, in cells expressing the mutant PTP1B, tyrosine phosphorylation of Src is enhanced and activity is reduced. Lysophosphatidic acid temporarily reverses the effects of the mutant PTP1B, suggesting the existence of a signaling pathway triggering focal adhesion assembly that bypasses the need for active PTP1B. PTP1B coimmunoprecipitates with β1-integrin from nonionic detergent extracts and colocalizes with vinculin and the ends of actin stress fibers in focal adhesions. Our data suggest that PTP1B is a critical regulatory component of integrin signaling pathways, which is essential for adhesion, spreading, and formation of focal adhesions. 相似文献
307.
The spermatogenesis, the spermiogenetic process and the structure of the mature spermatozoon of Acanthodasys aculeatus (Gastrotricha, Macrodasyida) are described from an ultrastructural point of view. Several spermatogonia in mitotic divisions were seen, proving that euthely of gastrotrichs does not concern gonads. Spermiogenesis is characterized by the early formation of both the acrosome and the axoneme, by the subsequent appearances of a perinuclear helix and of a complex axial tubular structure in the acrosome and by the late development of the peraxonemal striated cylinder. The mature spermatozoon is filiform, and composed of a spiralized acrosome, a helical nuclear–mitochondrial complex and a long flagellum. The acrosome contains an axial tubular structure and the spring-shaped nucleus delimits a single, long mitochondrion. A perinuclear helix formed by the pro-acrosome surrounds the nuclear–mitochondrial complex extending for its whole length. A monolayered, obliquely striated cylinder encloses the 9 × 2 + 2 axoneme; its terminal part is empty because of the shortness of the axoneme. 相似文献
308.
The thymus produces humoral factors that induce the proliferation and differentiation of T cells which are responsible for cell-mediated immunity. Experimental data have suggested that this thymic hormone production is modulated by the neuroendocrine network and, in particular, by growth hormone (GH) and thyroid hormones. To study the role played by GH in thymic endocrine activity in humans, the circulating level of one of the best known thymic peptides, i.e. thymulin (Zn-FTS), has been determined, after a washout period of 2 weeks without GH treatment, in GH-deficient children before and after a single injection of GH. The basal thymulin level is consistently lower in GH-deficient children than in healthy age-matched controls. A single injection of GH induces a significant increment of the thymulin level for at least 48 h. Since thymulin activity may also depend on zinc bioavailability, on thyroid hormone turnover and on the eventual presence of thymulin-inhibitory substances, all these aspects have been checked. No supporting evidence regarding the existence of these kinds of interferences in GH-deficient children has been substantiated. A positive correlation has been found between the serum level of insulin-like growth factor I, but not of GH, and thymulin activity. These data suggest that GH may directly or indirectly modulate the thymic endocrine function in humans. Whether and to what extent such a modulation is relevant to the functioning of the immune system remains to be ascertained. 相似文献
309.
The spatial and temporal expression patterns of cytokeratins, vimentin, epithelial growth factor (EGF) and transforming growth
factor alpha (TGF-α), were investigated in the 5–9-week old human mesonephros and metanephros. Vimentin was found in all mesonephric
structures, while cytokeratins were seen only in the mesonephric tubules. EGF and TGF-α were detected early in all mesonephric
structures, and immunoreactivity to both factors decreased in later stages. In the 5–6-week metanephros, vimentin immunoreactivity
was found in all structures and later increased in the collecting system and interstitium. In the 5th week, cytokeratins 8
and 19 appeared in the ureteric bud and ampullae, and later showed increasing immunoreactivity in the collecting system and
nephrons. The coexpression of intermediate filament proteins in metanephric development is a temporary feature and might be
associated with mesenchymal to epithelial transformation of developing nephrons. In adult kidneys, such coexpression is associated
with fibrosis or carcinomatous changes. At early stages, immunoreactivity to EGF and TGF-α was detected in all metanephric
structures and from the 7th week onward, it decreased in differentiating nephrons. EGF and TGF-α patterns of appearance indicate
their role in induction, proliferation and growth of metanephric structures. Disturbances in that pattern might cause reduction
in kidney growth. 相似文献
310.
Sapieha P Sirinyan M Hamel D Zaniolo K Joyal JS Cho JH Honoré JC Kermorvant-Duchemin E Varma DR Tremblay S Leduc M Rihakova L Hardy P Klein WH Mu X Mamer O Lachapelle P Di Polo A Beauséjour C Andelfinger G Mitchell G Sennlaub F Chemtob S 《Nature medicine》2008,14(10):1067-1076
Vascularization is essential for tissue development and in restoration of tissue integrity after an ischemic injury. In studies of vascularization, the focus has largely been placed on vascular endothelial growth factor (VEGF), yet other factors may also orchestrate this process. Here we show that succinate accumulates in the hypoxic retina of rodents and, via its cognate receptor G protein-coupled receptor-91 (GPR91), is a potent mediator of vessel growth in the settings of both normal retinal development and proliferative ischemic retinopathy. The effects of GPR91 are mediated by retinal ganglion neurons (RGCs), which, in response to increased succinate levels, regulate the production of numerous angiogenic factors including VEGF. Accordingly, succinate did not have proangiogenic effects in RGC-deficient rats. Our observations show a pathway of metabolite signaling where succinate, acting through GPR91, governs retinal angiogenesis and show the propensity of RGCs to act as sensors of ischemic stress. These findings provide a new therapeutic target for modulating revascularization. 相似文献