905 resultados para atrophy signaling
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Signal initiation by engagement of the TCR triggers actin rearrangements, receptor clustering, and dynamic organization of signaling complexes to elicit and sustain downstream signaling. Nef, a pathogenicity factor of HIV, disrupts early TCR signaling in target T cells. To define the mechanism underlying this Nef-mediated signal disruption, we employed quantitative single-cell microscopy following surface-mediated TCR stimulation that allows for dynamic visualization of distinct signaling complexes as microclusters (MCs). Despite marked inhibition of actin remodeling and cell spreading, the induction of MCs containing TCR-CD3 or ZAP70 was not affected significantly by Nef. However, Nef potently inhibited the subsequent formation of MCs positive for the signaling adaptor Src homology-2 domain-containing leukocyte protein of 76 kDa (SLP-76) to reduce MC density in Nef-expressing and HIV-1-infected T cells. Further analyses suggested that Nef prevents formation of SLP-76 MCs at the level of the upstream adaptor protein, linker of activated T cells (LAT), that couples ZAP70 to SLP-76. Nef did not disrupt pre-existing MCs positive for LAT. However, the presence of the viral protein prevented de novo recruitment of active LAT into MCs due to retargeting of LAT to an intracellular compartment. These modulations in MC formation and composition depended on Nef's ability to simultaneously disrupt both actin remodeling and subcellular localization of TCR-proximal machinery. Nef thus employs a dual mechanism to disturb early TCR signaling by limiting the communication between LAT and SLP-76 and preventing the dynamic formation of SLP-76-signaling MCs.
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Purpose: To describe the occurrence of geographic atrophy in patients with retinal angiomatous proliferation (RAP). Methods: Demographics, visual acuity, color fundus photographs, fluorescein and indocyanine green angiograms, and fundus autofluorescence and near-infrared autofluorescence images were reviewed in 53 patients (66 eyes) with RAP. Results: Of 53 treatment-naive eyes, 19 (36%) had atrophy at baseline. Of 66 eyes, 57 (86%) developed de novo atrophy or enlargement of preexisting areas of atrophy during the follow-up (median, 17 months; range, 3-53 months) after treatment. Areas of atrophy were observed at the site of the RAP (58 of 66 eyes, 88%) of a previously existing pigment epithelial detachment (18 of 44 eyes; 41%) and elsewhere (43 of 66 eyes, 65%). At presentation, RAP was found to be frequently associated with increased autofluorescence at the fovea because of cystoid macular edema (36 of 53 eyes, 68%) and reduced autofluorescence because of hard exudation (38 of 53 eyes, 72%) and intraretinal hemorrhages (32 of 53 eyes, 60%). Background reticular (39%) and homogeneous (36%) autofluorescence were most commonly observed. Conclusion: Geographic atrophy occurs frequently in patients with RAP after treatment. This information, if confirmed in other cohorts, would be valuable for the counseling of patients with this disease and for the understanding of the pathogenesis of this condition and its progression after treatment. Copyright © 2011 Lippincott Williams &Wilkins.
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PURPOSE:: To evaluate the occurrence of retinal pigment epithelial atrophy in patients with age-related macular degeneration undergoing anti-vascular endothelial growth factor therapy. METHODS:: The study is a retrospective review. Eligible were patients with age-related macular degeneration and choroidal neovascular membranes treated with anti-vascular endothelial growth factor between October 2007 and February 2011; they were followed for >3 months, with fundus photographs and fluorescein angiography at baseline and with autofluorescence and near-infrared autofluorescence images at baseline and follow-up. Demographics, visual acuity, the type of choroidal neovascular membranes, the number of treatments performed, and the length of follow-up were recorded. Autofluorescence and near-infrared autofluorescence images were evaluated for the presence or absence of areas of reduced signal. A multilevel logistic regression model was used to investigate the factors that may be associated with progression of atrophy at follow-up, which was the primary outcome of this study. RESULTS:: Sixty-three patients (72 eyes) were followed for a median of 16 months (range, 3-36 months). Atrophy at baseline was observed in 47% (34/72) of eyes; progression of atrophy occurred in 62% (45/72) of eyes at the last visit. The number of anti-vascular endothelial growth factor injections received was statistically significantly associated with the progression of atrophy at follow-up (odds ratio, 1.35; 95% confidence interval, 1.05-1.73; P = 0.02). CONCLUSION:: Atrophy was frequently observed in patients with age-related macular degeneration and choroidal neovascular membranes undergoing anti-vascular endothelial growth factor therapy.
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• PURPOSE: To evaluate retinal pigment epithelial (RPE) atrophy in patients with Stargardt disease using autofluorescence imaging (AF). • DESIGN: Retrospective observational case series. • METHODS: Demographics, best-corrected visual acuity (BCVA), AF images, and electrophysiology responses (group 1, macular dysfunction; group 2, macula + cone dysfunction; group 3, macula + cone-rod dysfunction) were evaluated at presentation and follow-up in a group of 12 patients (24 eyes) with Stargardt disease. The existence, development, and rate of enlargement of areas of RPE atrophy over time were evaluated using AF imaging. A linear regression model was used to investigate the effects of AF and electrophysiology on rate of atrophy enlargement and BCVA, adjusting for age of onset and duration of disease. • RESULTS: Eight male and 4 female patients (median age 42 years; range 24-69 years) were followed for a median of 41.5 months (range 13-66 months). All 12 patients had reduced AF compatible with RPE atrophy at presentation and in all patients the atrophy enlarged during follow-up. The mean rate of atrophy enlargement for all patients was 1.58 mm /y (SD 1.25 mm /y; range 0.13-5.27 mm /y). Only the pattern of functional loss present as detected by electrophysiology was statistically significantly associated with the rate of atrophy enlargement when correcting for other variables (P <.001), with patients in group 3 (macula + cone-rod dysfunction) having the fastest rate of atrophy enlargement (1.97 mm /y, SD 0.70 mm /y) (group 1 [macula] 1.09 mm /y, SD 0.53 mm /y; group 2 [macula + cone] 1.89 mm /y, SD 2.27 mm /y). • CONCLUSION: Variable rates of atrophy enlargement were observed in patients with Stargardt disease. The pattern of functional loss detected on electrophysiology was strongly associated with the rate of atrophy enlargement over time, thus serving as the best prognostic indicator for patients with this inherited retinal disease. © 2012 Elsevier Inc. All rights reserved.
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Previous studies have shown that CCL2/CX3CR1 deficient mice on C57BL/6N background (with rd8 mutation) have an early onset (6 weeks) of spontaneous retinal degeneration. In this study, we generated CCL2(-/-)CX3CR1(GFP/GFP) mice on the C57BL/6J background. Retinal degeneration was not detected in CCL2(-/-)CX3CR1(GFP/GFP) mice younger than 6 months. Patches of whitish/yellowish fundus lesions were observed in 17~60% of 12-month, and 30~100% of 18-month CCL2(-/-)CX3CR1(GFP/GFP) mice. Fluorescein angiography revealed no choroidal neovascularisation in these mice. Patches of retinal pigment epithelium (RPE) and photoreceptor damage were detected in 30% and 50% of 12- and 18-month CCL2(-/-)CX3CR1(GFP/GFP) mice respectively, but not in wild-type mice. All CCL2(-/-)CX3CR1(GFP/GFP) mice exposed to extra-light (~800lux, 6 h/day, 6 months) developed patches of retinal atrophy, and only 20-25% of WT mice which underwent the same light treatment developed atrophic lesions. In addition, synaptophysin expression was detected in the outer nucler layer (ONL) of area related to photoreceptor loss in CCL2(-/-)CX3CR1(GFP/GFP) mice. Markedly increased rhodopsin but reduced cone arrestin expression was observed in retinal outer layers in aged CCL2(-/-)CX3CR1(GFP/GFP) mice. GABA expression was reduced in the inner retina of aged CCL2(-/-)CX3CR1(GFP/GFP) mice. Significantly increased Müller glial and microglial activation was observed in CCL2(-/-)CX3CR1(GFP/GFP) mice compared to age-matched WT mice. Macrophages from CCL2(-/-)CX3CR1(GFP/GFP) mice were less phagocytic, but expressed higher levels of iNOS, IL-1ß, IL-12 and TNF-a under hypoxia conditions. Our results suggest that the deletions of CCL2 and CX3CR1 predispose mice to age- and light-mediated retinal damage. The CCL2/CX3CR1 deficient mouse may thus serve as a model for age-related atrophic degeneration of the RPE, including the dry type of macular degeneration, geographic atrophy.
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Pericyte loss is a cardinal feature of early diabetic retinopathy. We previously reported that highly oxidized-glycated low density lipoprotein (HOG-LDL) induces pericyte apoptosis in vitro. In this study, we investigated the role of the mitogen-activated protein kinase (MAPK) signaling pathways in HOG-LDL-induced apoptosis in human pericytes.
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Sirolimus-eluting stent therapy has achieved considerable success in overcoming coronary artery restenosis. However, there remain a large number of patients presenting with restenosis after the treatment, and the source of its persistence remains unclarified. Although recent evidence supports the contribution of vascular stem/progenitor cells in restenosis formation, their functional and molecular responses to sirolimus are largely unknown.
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The natural isoquinoline alkaloid berberine exhibits a wide spectrum of biological activities including antitumor activity, but its mechanism of action remains to be fully elucidated. Here, we report that berberine induced apoptosis in human melanoma cells, through a process that involved mitochondria and caspase activation. Berberine-induced activation of a number of caspases, including caspases 3, 4, 7, 8, and 9. Pan-caspase inhibitor, z-VAD-fmk, and caspase-8 and caspase-9 inhibitors prevented apoptosis. Berberine also led to the generation of the p20 cleavage fragment of BAP31, involved in directing proapoptotic signals between the endoplasmic reticulum and the mitochondria. Treatment of SK-MEL-2 melanoma cells with berberine induced disruption of the mitochondrial transmembrane potential, release of cytochrome c and apoptosis-inducing factor from the mitochondria to the cytosol, generation of reactive oxygen species (ROS), and a decreased ATP/ADP ratio. Overexpression of bcl-xL by gene transfer prevented berberine-induced cell death, mitochondrial transmembrane potential loss, and cytochrome c and apoptosis-inducing factor release, but not ROS generation. N-acetyl-L-cysteine inhibited the production of ROS, but did not abrogate the berberine-induced apoptosis. Inhibition of extracellular signal-regulated kinase (ERK) phosphorylation, by using the mitogen-activated protein kinase/ERK kinase inhibitor PD98059, and reduction of B-RAF levels by silencing RNA induced cell death of SK-MEL-2 cells, and diminished the berberine concentration required to promote apoptosis. These data show that berberine-induced apoptosis in melanoma cells involves mitochondria and caspase activation, but ROS generation was not essential. Our results indicate that inhibition of B-RAF/ERK survival signaling facilitates the cell death response triggered by berberine. © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins.
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Pigmented paravenous chorioretinal atrophy (PPCRA) is an unusual retinal degeneration characterized by accumulation of pigmentation along retinal veins. The purpose of this study was to describe the phenotype of a family with PPCRA, determine the mode of inheritance, and identify the causal mutation.
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The regulator of the G-protein signaling 4 (RGS4) gene was shown to have a different expression pattern in schizophrenia patients in a microarray study. A family-based study subsequently implicated the association of this gene with schizophrenia. We replicated the study with our sample from the Irish Study of High Density Schizophrenia Families (ISHDSF). Single marker transmission disequilibrium tests (TDT) for the four core SNPs showed modest association for SNP 18 (using a narrow diagnostic approach with FBAT P = 0.044; with PDT P = 0.0073) and a trend for SNP 4 (with FBAT P = 0.1098; with PDT P = 0.0249). For SNP 1 and 7, alleles overtransmitted to affected subjects were the same as previously reported. Haplotype analyses suggested that haplotype G-G-G for SNP1-4-18, which is the most abundant haplotype (42.3%) in the Irish families, was associated with the disease (narrow diagnosis, FBAT P = 0.0061, PDT P = 0.0498). This was the same haplotype implicated in the original study. While P values were not corrected for multiple testing because of the clear prior hypothesis, these results could be interpreted as supporting evidence for the association between RGS4 and schizophrenia.
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Purpose
Recent in vitro results have shown significant contributions to cell killing from signaling effects at doses that are typically used in radiation therapy. This study investigates whether these in vitro observations can be reconciled with in vivo knowledge and how signaling may have an impact on future developments in radiation therapy.
Methods and Materials
Prostate cancer treatment plans were generated for a series of 10 patients using 3-dimensional conformal therapy, intensity modulated radiation therapy (IMRT), and volumetric modulated arc therapy techniques. These plans were evaluated using mathematical models of survival following modulated radiation exposures that were developed from in vitro observations and incorporate the effects of intercellular signaling. The impact on dose-volume histograms and mean doses were evaluated by converting these survival levels into "signaling-adjusted doses" for comparison.
Results
Inclusion of intercellular communication leads to significant differences between the signalling-adjusted and physical doses across a large volume. Organs in low-dose regions near target volumes see the largest increases, with mean signaling-adjusted bladder doses increasing from 23 to 33 Gy in IMRT plans. By contrast, in high-dose regions, there is a small decrease in signaling-adjusted dose due to reduced contributions from neighboring cells, with planning target volume mean doses falling from 74 to 71 Gy in IMRT. Overall, however, the dose distributions remain broadly similar, and comparisons between the treatment modalities are largely unchanged whether physical or signaling-adjusted dose is compared. Conclusions Although incorporating cellular signaling significantly affects cell killing in low-dose regions and suggests a different interpretation for many phenomena, their effect in high-dose regions for typical planning techniques is comparatively small. This indicates that the significant signaling effects observed in vitro are not contradicted by comparison with clinical observations. Future investigations are needed to validate these effects in vivo and to quantify their ranges and potential impact on more advanced radiation therapy techniques.
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Mutations that result in loss of function of Nod2, an intracellular receptor for bacterial peptidoglycan, are associated with Crohn's disease. Here we found that the E3 ubiquitin ligase Pellino3 was an important mediator in the Nod2 signaling pathway. Pellino3-deficient mice had less induction of cytokines after engagement of Nod2 and had exacerbated disease in various experimental models of colitis. Furthermore, expression of Pellino3 was lower in the colons of patients with Crohn's disease. Pellino3 directly bound to the kinase RIP2 and catalyzed its ubiquitination. Loss of Pellino3 led to attenuation of Nod2-induced ubiquitination of RIP2 and less activation of the transcription factor NF-?B and mitogen-activated protein kinases (MAPKs). Our findings identify RIP2 as a substrate for Pellino3 and Pellino3 as an important mediator in the Nod2 pathway and regulator of intestinal inflammation. © 2013 Nature America, Inc. All rights reserved.