排序方式: 共有110条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
tRNA's modifications bring order to gene expression 总被引:3,自引:0,他引:3
85.
Molecular integration of wingless, decapentaplegic, and autoregulatory inputs into Distalless during Drosophila leg development 总被引:2,自引:0,他引:2
The development of the Drosophila leg requires both Decapentaplegic (Dpp) and Wingless (Wg), two signals that establish the proximo-distal (PD) axis by activating target genes such as Distalless (Dll). Dll expression in the leg depends on a Dpp- and Wg-dependent phase and a maintenance phase that is independent of these signals. Here, we show that accurate Dll expression in the leg results from the synergistic interaction between two cis-regulatory elements. The Leg Trigger (LT) element directly integrates Wg and Dpp inputs and is only active in cells receiving high levels of both signals. The Maintenance (M) element is able to maintain Wg- and Dpp-independent expression, but only when in cis to LT. M, which includes the native Dll promoter, functions as an autoregulatory element by directly binding Dll. The "trigger-maintenance" model describes a mechanism by which secreted morphogens act combinatorially to induce the stable expression of target genes. 相似文献
86.
87.
88.
Maintenance of the keratocyte phenotype during cell proliferation stimulated by insulin 总被引:2,自引:0,他引:2
Musselmann K Alexandrou B Kane B Hassell JR 《The Journal of biological chemistry》2005,280(38):32634-32639
Keratocytes normally express high levels of aldehyde dehydrogenase and keratocan. They proliferate and lose their keratocyte markers when they become fibroblastic during corneal wound healing. Keratocytes cultured in fetal bovine serum also become fibroblastic, proliferate, and lose these markers. In this report, we studied the effects of three serum growth factors, fibroblast growth factor-2, insulin, and platelet-derived growth factor-BB, on keratocyte proliferation and the maintenance of the keratocyte markers in 7-day cultures in cells plated at low (5,000 cells/cm2) and high (20,000 cells/cm2) density in serum-free medium. Keratocyte proliferation was measured by [3H]thymidine incorporation and by DNA content of the cultures. Cytosolic aldehyde dehydrogenase and keratocan accumulated in the medium were quantified by Western blot. The results showed that all the growth factors stimulated proliferation, but insulin stimulated proliferation more consistently. The keratocyte markers aldehyde dehydrogenase and keratocan were maintained after 7 days in culture in all growth factors, but keratocyte cell morphology was only maintained in medium containing insulin. Most of the proteoglycans were degraded in cultures of keratocytes plated at low density and cultured in the absence of growth factors. This degradation was prevented when keratocytes were cultured in the presence of the growth factors or when keratocytes were plated at high density. The results of this study show that insulin can expand keratocytes in vitro, maintain their phenotype, and prevent proteoglycan degradation. 相似文献
89.
Mohamed El?Beheiry Silvan Türkcan Maximilian?U. Richly Antoine Triller Antigone Alexandrou Maxime Dahan Jean-Baptiste Masson 《Biophysical journal》2016,110(6):1209-1215
Tracking single molecules in living cells provides invaluable information on their environment and on the interactions that underlie their motion. New experimental techniques now permit the recording of large amounts of individual trajectories, enabling the implementation of advanced statistical tools for data analysis. In this primer, we present a Bayesian approach toward treating these data, and we discuss how it can be fruitfully employed to infer physical and biochemical parameters from single-molecule trajectories. 相似文献
90.
Estella Zuccolo Dlzar A. Kheder Dmitry Lim Angelica Perna Francesca Di Nezza Laura Botta Giorgia Scarpellino Sharon Negri Simona Martinotti Teresa Soda Greta Forcaia Laura Riboni Elia Ranzato Giulio Sancini Luigi Ambrosone Egidio D’Angelo Germano Guerra Francesco Moccia 《Journal of cellular physiology》2019,234(4):3538-3554
The neurotransmitter glutamate increases cerebral blood flow by activating postsynaptic neurons and presynaptic glial cells within the neurovascular unit. Glutamate does so by causing an increase in intracellular Ca2+ concentration ([Ca2+]i) in the target cells, which activates the Ca2+/Calmodulin-dependent nitric oxide (NO) synthase to release NO. It is unclear whether brain endothelial cells also sense glutamate through an elevation in [Ca2+]i and NO production. The current study assessed whether and how glutamate drives Ca2+-dependent NO release in bEND5 cells, an established model of brain endothelial cells. We found that glutamate induced a dose-dependent oscillatory increase in [Ca2+]i, which was maximally activated at 200 μM and inhibited by α-methyl-4-carboxyphenylglycine, a selective blocker of Group 1 metabotropic glutamate receptors. Glutamate-induced intracellular Ca2+ oscillations were triggered by rhythmic endogenous Ca2+ mobilization and maintained over time by extracellular Ca2+ entry. Pharmacological manipulation revealed that glutamate-induced endogenous Ca2+ release was mediated by InsP3-sensitive receptors and nicotinic acid adenine dinucleotide phosphate (NAADP) gated two-pore channel 1. Constitutive store-operated Ca2+ entry mediated Ca2+ entry during ongoing Ca2+ oscillations. Finally, glutamate evoked a robust, although delayed increase in NO levels, which was blocked by pharmacologically inhibition of the accompanying intracellular Ca2+ signals. Of note, glutamate induced Ca2+-dependent NO release also in hCMEC/D3 cells, an established model of human brain microvascular endothelial cells. This investigation demonstrates for the first time that metabotropic glutamate-induced intracellular Ca2+ oscillations and NO release have the potential to impact on neurovascular coupling in the brain. 相似文献