scholarly journals Adaptive potentiation in rod photoreceptors after light exposure

2014 ◽  
Vol 143 (6) ◽  
pp. 733-743 ◽  
Author(s):  
Alex S. McKeown ◽  
Timothy W. Kraft
Keyword(s):  
Time Constant ◽  
Molecular Mechanisms ◽  
Kinase Inhibitor ◽  
Light Exposure ◽  
Tyrosine Phosphatase ◽  
Light Response ◽  
Rod Photoreceptor ◽  
Rod Photoreceptors ◽  
Light History ◽  
Insulin Receptor Kinase

Photoreceptors adapt to changes in illumination by altering transduction kinetics and sensitivity, thereby extending their working range. We describe a previously unknown form of rod photoreceptor adaptation in wild-type (WT) mice that manifests as a potentiation of the light response after periods of conditioning light exposure. We characterize the stimulus conditions that evoke this graded hypersensitivity and examine the molecular mechanisms of adaptation underlying the phenomenon. After exposure to periods of saturating illumination, rods show a 10–35% increase in circulating dark current, an adaptive potentiation (AP) to light exposure. This potentiation grows as exposure to light is extended up to 3 min and decreases with longer exposures. Cells return to their initial dark-adapted sensitivity with a time constant of recovery of ∼7 s. Halving the extracellular Mg concentration prolongs the adaptation, increasing the time constant of recovery to 13.3 s, but does not affect the magnitude of potentiation. In rods lacking guanylate cyclase activating proteins 1 and 2 (GCAP−/−), AP is more than doubled compared with WT rods, and halving the extracellular Mg concentration does not affect the recovery time constant. Rods from a mouse expressing cyclic nucleotide–gated channels incapable of binding calmodulin also showed a marked increase in the amplitude of AP. Application of an insulin-like growth factor-1 receptor (IGF-1R) kinase inhibitor (Tyrphostin AG1024) blocked AP, whereas application of an insulin receptor kinase inhibitor (HNMPA(AM)3) failed to do so. A broad-acting tyrosine phosphatase inhibitor (orthovanadate) also blocked AP. Our findings identify a unique form of adaptation in photoreceptors, so that they show transient hypersensitivity to light, and are consistent with a model in which light history, acting via the IGF-1R, can increase the sensitivity of rod photoreceptors, whereas the photocurrent overshoot is regulated by Ca-calmodulin and Ca2+/Mg2+-sensitive GCAPs.

scholarly journals Early signalling mechanism in colonic epithelial cell response to gastrin

1995 ◽  
Vol 311 (3) ◽  
pp. 945-950 ◽  
Author(s):  
R R Yassin ◽  
K M Little
Keyword(s):  
Tyrosine Phosphorylation ◽  
Molecular Mechanisms ◽  
Kinase Inhibitor ◽  
Tyrosine Phosphatase ◽  
Promoting Effect ◽  
Kinase C ◽  
Growth Promoting ◽  
Colonic Cells ◽  
Signalling Cascade ◽  
Isolation Buffer

The hormone gastrin exerts a growth-promoting effect on gastrointestinal cells. The molecular mechanisms by which colonic epithelial cells respond to gastrin are still poorly understood. In this study, we demonstrate a novel feature of the action of gastrin on normal colonic cells, namely the rapid phosphorylation on tyrosine of phospholipase C gamma 1 (PLC gamma 1). Tyrosine phosphorylation of PLC gamma 1, elicited by gastrin, was transient, concentration-dependent, and was abrogated by pretreating the colonic cells with the gastrin-receptor antagonist proglumide, the tyrosine kinase inhibitor genistein, and by removal of the tyrosine phosphatase inhibitor orthovanadate from the isolation buffer. Tyrosine phosphorylation of PLC gamma 1 correlated with the time- and concentration-dependent decrease in the mass of membrane phosphatidylinositol 4,5-bisphosphate (PIP2) and the increase in the epithelial concentration of inositol 1,4,5-trisphosphate (IP3). Likewise, the stimulated increase in IP3 was also prevented by proglumide and genistein. Gastrin induced a definite but transient increase in the intracellular concentration of free Ca2+ [Ca2+]i, and increased membrane-translocation of immunoreactive alpha- and beta-protein kinase C. The data thus indicate that gastrin elicits at least one signalling cascade, through rapid tyrosine phosphorylation of PLC gamma 1, leading to the activation of a PIP2-specific PLC pathway.

A novel MyD-1 (SIRP-1α) signaling pathway that inhibits LPS-induced TNFα production by monocytes

Blood ◽  
2003 ◽  
Vol 102 (7) ◽  
pp. 2532-2540 ◽  
Author(s):  
Rosemary E. Smith ◽  
Vanshree Patel ◽  
Sandra D. Seatter ◽  
Maureen R. Deehan ◽  
Marion H. Brown ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Molecular Mechanisms ◽  
Mononuclear Cells ◽  
Kinase Inhibitor ◽  
Tyrosine Phosphatase ◽  
Peripheral Blood Mononuclear ◽  
Necrosis Factor Alpha ◽  
Purified Protein Derivative ◽  
Sequential Activation ◽  
Novel Target

Abstract MyD-1 (CD172) is a member of the family of signal regulatory phosphatase (SIRP) binding proteins, which is expressed on human CD14+ monocytes and dendritic cells. We now show a novel role for MyD-1 in the regulation of the innate immune system by pathogen products such as lipopolysaccharide (LPS), purified protein derivative (PPD), and Zymosan. Specifically, we demonstrate that ligation of MyD-1 on peripheral blood mononuclear cells (PBMCs) inhibits tumor necrosis factor alpha (TNFα) secretion but has no effect on other cytokines induced in response to each of these products. In an attempt to understand the molecular mechanisms underlying this surprisingly selective effect we investigated signal transduction pathways coupled to MyD-1. Ligation of the SIRP was found to recruit the tyrosine phosphatase SHP-2 and promote sequential activation of phosphatidylinositol (PI) 3-kinase, phospholipase D, and sphingosine kinase. Inhibition of LPS-induced TNFα secretion by MyD-1 appears to be mediated by this pathway, as the PI 3-kinase inhibitor wortmannin restores normal LPS-driven TNFα secretion. MyD-1-coupling to this PI 3-kinase-dependent signaling pathway may therefore present a novel target for the development of therapeutic strategies for combating TNFα production and consequent inflammatory disease. (Blood. 2003;102:2532-2540)

scholarly journals New Insights into the Pathogenesis of Systemic Mastocytosis

2021 ◽  
Vol 22 (9) ◽  
pp. 4900
Author(s):  
Zhixiong Li
Keyword(s):  
Molecular Mechanisms ◽  
Kinase Inhibitor ◽  
Systemic Mastocytosis ◽  
Treatment Strategies ◽  
The United States ◽  
European Medicines Agency ◽  
Myeloid Neoplasm ◽  
Organ Systems ◽  
United States Food ◽  
Kit D816v

Mastocytosis is a type of myeloid neoplasm characterized by the clonal, neoplastic proliferation of morphologically and immunophenotypically abnormal mast cells that infiltrate one or more organ systems. Systemic mastocytosis (SM) is a more aggressive variant of mastocytosis with extracutaneous involvement, which might be associated with multi-organ dysfunction or failure and shortened survival. Over 80% of patients with SM carry the KIT D816V mutation. However, the KIT D816V mutation serves as a weak oncogene and appears to be a late event in the pathogenesis of mastocytosis. The management of SM is highly individualized and was largely palliative for patients without a targeted form of therapy in past decades. Targeted therapy with midostaurin, a multiple kinase inhibitor that inhibits KIT, has demonstrated efficacy in patients with advanced SM. This led to the recent approval of midostaurin by the United States Food and Drug Administration and European Medicines Agency. However, the overall survival of patients treated with midostaurin remains unsatisfactory. The identification of genetic and epigenetic alterations and understanding their interactions and the molecular mechanisms involved in mastocytosis is necessary to develop rationally targeted therapeutic strategies. This review briefly summarizes recent developments in the understanding of SM pathogenesis and potential treatment strategies for patients with SM.

scholarly journals The Analysis of PTPN6 for Bladder Cancer: An Exploratory Study Based on TCGA

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Chengquan Shen ◽  
Jing Liu ◽  
Jirong Wang ◽  
Xiaokun Yang ◽  
Haitao Niu ◽  
...  
Keyword(s):  
Bladder Cancer ◽  
T Cells ◽  
Survival Analysis ◽  
Prognostic Value ◽  
Molecular Mechanisms ◽  
Tyrosine Phosphatase ◽  
Gene Set Enrichment Analysis ◽  
Expression Level ◽  
Pathologic Features ◽  
The Relationship

PTPN6 (protein tyrosine phosphatase nonreceptor type 6), a tyrosine phosphatase, is known to be signaling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitotic cycle, and oncogenic transformation. Previous studies have demonstrated that PTPN6 expression is relatively elevated in several malignancies. However, the role of PTPN6 in bladder cancer (BC) remains unclear. The purpose of this study was to explore the prognostic value of PTPN6 in BC. RNA-seq data from The Cancer Genome Atlas (TCGA) was used to identify the expression level of PTPN6 in BC. The relationship between clinical pathologic features and PTPN6 were analyzed with the Wilcoxon signed-rank test. The prognostic and predictive value of PTPN6 was evaluated by survival analysis and nomogram. Gene Set Enrichment Analysis (GSEA) was conducted to explore the potential molecular mechanisms of PTPN6 in BC. Finally, Tumor Immune Estimation Resource (TIMER) was applied to investigate the relationship between PTPN6 and immune cell infiltration in the tumor microenvironment. Results indicated that PTPN6 was overexpressed in BC tissues compared with normal bladder tissues and was significantly correlated with grade, stage, T, and N. Survival analysis showed that low expression of PTPN6 was significantly related to the poor overall survival (OS) in BC patients. Coexpression analysis showed that PTPN6 and TNFRSF14 (Tumor necrosis factor receptor superfamily member 14) have a close correlation in BC. GSEA showed that multiple cancer-associated signaling pathways are differentially enriched in the PTPN6 high expression phenotype. Moreover, the expression level of PTPN6 was positively associated with the infiltration of B cells, CD4+T cells, dendritic cells, and neutrophils and negatively associated with CD8+ T cells and macrophages in BC. In conclusion, we identified that PTPN6 may be a novel prognostic biomarker in BC based on the TCGA database. Further clinical trials are needed to confirm our observations and mechanisms underlying the prognostic value of PTPN6 in BC also deserve further experimental exploration.

scholarly journals A priori checking of the light-response and data quality before extended data collection in pump–probe photocrystallography experiments

2017 ◽  
Vol 73 (1) ◽  
pp. 23-26 ◽  
Author(s):  
Philip Coppens ◽  
Anna Makal ◽  
Bertrand Fournier ◽  
Katarzyna N. Jarzembska ◽  
Radosław Kamiński ◽  
...  
Keyword(s):  
Data Collection ◽  
Light Exposure ◽  
A Priori ◽  
Light Response ◽  
Response Ratio ◽  
Full Data ◽  
Pump Probe ◽  
Ratio Correlation ◽  
Induced Signal

In picosecond and slower pump–probe diffraction experiments, collection of response–ratio correlation sets prior to full data collection provides an invaluable confirmation of the existence of a light-induced signal prior to full data collection. If a response to light exposure is observed, the quality of the data being collected can be assessed. A number of such correlation plots both for synchrotron and in-house pump–probe data collection are presented.

scholarly journals Context-dependent expression of the foraging gene in field colonies of ants: the interacting roles of age, environment and task

2016 ◽  
Vol 283 (1837) ◽  
pp. 20160841 ◽  
Author(s):  
Krista K. Ingram ◽  
Deborah M. Gordon ◽  
Daniel A. Friedman ◽  
Michael Greene ◽  
John Kahler ◽  
...  
Keyword(s):  
Gene Expression ◽  
Task Allocation ◽  
Molecular Mechanisms ◽  
Light Exposure ◽  
Genetic Regulation ◽  
Behavioural Plasticity ◽  
Harvester Ants ◽  
Ontogenetic Changes ◽  
Context Dependent ◽  
And Task

Task allocation among social insect workers is an ideal framework for studying the molecular mechanisms underlying behavioural plasticity because workers of similar genotype adopt different behavioural phenotypes. Elegant laboratory studies have pioneered this effort, but field studies involving the genetic regulation of task allocation are rare. Here, we investigate the expression of the foraging gene in harvester ant workers from five age- and task-related groups in a natural population, and we experimentally test how exposure to light affects foraging expression in brood workers and foragers. Results from our field study show that the regulation of the foraging gene in harvester ants occurs at two time scales: levels of foraging mRNA are associated with ontogenetic changes over weeks in worker age, location and task, and there are significant daily oscillations in foraging expression in foragers. The temporal dissection of foraging expression reveals that gene expression changes in foragers occur across a scale of hours and the level of expression is predicted by activity rhythms: foragers have high levels of foraging mRNA during daylight hours when they are most active outside the nests. In the experimental study, we find complex interactions in foraging expression between task behaviour and light exposure. Oscillations occur in foragers following experimental exposure to 13 L : 11 D (LD) conditions, but not in brood workers under similar conditions. No significant differences were seen in foraging expression over time in either task in 24 h dark (DD) conditions. Interestingly, the expression of foraging in both undisturbed field and experimentally treated foragers is also significantly correlated with the expression of the circadian clock gene, cycle . Our results provide evidence that the regulation of this gene is context-dependent and associated with both ontogenetic and daily behavioural plasticity in field colonies of harvester ants. Our results underscore the importance of assaying temporal patterns in behavioural gene expression and suggest that gene regulation is an integral mechanism associated with behavioural plasticity in harvester ants.

Secretin regulates paracellular permeability in canine gastric monolayers by a Src kinase-dependent pathway

2002 ◽  
Vol 283 (4) ◽  
pp. G893-G899 ◽  
Author(s):  
Monica C. Chen ◽  
Travis E. Solomon ◽  
Eduardo Perez Salazar ◽  
Robert Kui ◽  
Enrique Rozengurt ◽  
...  
Keyword(s):  
Gastric Mucosa ◽  
Epithelial Cells ◽  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitor ◽  
Tyrosine Phosphorylation ◽  
Molecular Mechanisms ◽  
Kinase Inhibitor ◽  
Paracellular Permeability ◽  
Maximal Response ◽  
Src Tyrosine Kinase

Previous studies found that epidermal growth factor (EGF) decreased paracellular permeability in gastric mucosa, but the other physiological regulators and the molecular mechanisms mediating these responses remain undefined. We investigated the role of secretin and Src in regulating paracellular permeability because secretin regulates gastric chief cell function and Src mediates events involving the cytoskeletal-membrane interface, respectively. Confluent monolayers were formed from canine gastric epithelial cells in short-term culture on Transwell filter inserts. Resistance was monitored in the presence of secretin with or without specific kinase inhibitors. Tyrosine phosphorylation of Src at Tyr416 was measured with a site-specific phosphotyrosine antibody. Basolateral, but not apical, secretin at concentrations from 1 to 100 nM dose dependently increased resistance; this response was rapid and sustained over hours. PP2 (10 μM), a selective Src tyrosine kinase inhibitor, but not the inactive isomer PP3, abolished the increase in resistance by secretin but only modestly attenuated apical EGF effects. AG-1478 (100 nM), a specific EGF receptor tyrosine kinase inhibitor, attenuated the resistance increase to EGF but not secretin. Secretin, but not EGF, induced tyrosine phosphorylation of Src at Tyr416 in a dose-dependent fashion, with the maximal response observed at 1 min. PP2, but not PP3, dramatically inhibited this tyrosine phosphorylation. Secretin increases paracellular resistance in gastric mucosa through a Src-mediated pathway, while the effect of EGF is Src independent. Src appears to mediate the physiological effects of this Gs-coupled receptor in primary epithelial cells.

scholarly journals Dorsal horn interneuron-derived Netrin-4 contributes to spinal sensitization in chronic pain via Unc5B

2016 ◽  
Vol 213 (13) ◽  
pp. 2949-2966 ◽  
Author(s):  
Yasufumi Hayano ◽  
Keiko Takasu ◽  
Yoshihisa Koyama ◽  
Moe Yamada ◽  
Koichi Ogawa ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Chronic Pain ◽  
Dorsal Horn ◽  
Molecular Mechanisms ◽  
Tyrosine Phosphatase ◽  
Intrathecal Administration ◽  
Human Spinal Cord ◽  
Similar Expression Pattern ◽  
Subsequent Activation ◽  
Spinal Sensitization

Because of the incomplete understanding of the molecular mechanisms that underlie chronic pain, the currently available treatments for this type of pain remain inefficient. In this study, we show that Netrin-4, a member of the axon guidance molecule family, was expressed in dorsal horn inner lamina II excitatory interneurons in the rat spinal cord. A similar expression pattern for Netrin-4 was also observed in human spinal cord. Behavioral analysis revealed that tactile and heat hyperalgesia after peripheral nerve injury or inflammation were abolished in Netrin-4–mutant rats. Transient suppression of Netrin-4 or its receptor Unc5B after injury could also prevent allodynia. Conversely, intrathecal administration of Netrin-4 protein to naive rats enhanced excitatory synaptic transmission in the dorsal horn and induced allodynia, suggesting that Netrin-4 is involved in spinal sensitization. Furthermore, the Unc5B receptor and subsequent activation of the tyrosine phosphatase SHP2 mediated Netrin-4–induced pain signaling in the spinal cord. These results identify Netrin-4 as a novel protein regulating spinal sensitization leading to chronic pain. Our findings provide evidence for the function of Netrin in the adult nervous system, as well as a previously unknown function in inducing pain signals from dorsal horn interneurons.

MicroRNA-138-1-3p sensitizes sorafenib to hepatocellular carcinoma by targeting PAK5 mediated β-catenin/ABCB1 signaling pathway

2020 ◽  
Author(s):  
Tong-tong Li ◽  
Jie Mou ◽  
Yao-jie Pan ◽  
Fu-chun Huo ◽  
Wen-qi Du ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Signaling Pathway ◽  
Molecular Mechanisms ◽  
Nuclear Translocation ◽  
Kinase Inhibitor ◽  
Flow Cytometric Analysis ◽  
Luciferase Reporter ◽  
Advanced Hepatocellular Carcinoma ◽  
Cell Viability Assay ◽  
Resistant Cells

Abstract Background: Kinase inhibitor sorafenib is the first-line targeted drug for advanced hepatocellular carcinoma (HCC) patients. However, the appearance of anti-cancer agents’ resistance has limited its therapeutic effect. Methods: In this study, quantitative real-time PCR (qPCR) and Western Blot were utilized to detect the levels of PAK5 in HCC sorafenib-resistant cells and their parental cells. The biological functions of miR-138-1-3p and PAK5 in sorafenib-resistant cells and their parental cells were explored by cell viability assay, plate colony formation assay and flow cytometric analysis. The potential mechanisms of PAK5 were evaluated via co-immunoprecipitation (co-IP), immunofluorescence, dual luciferase reporter assay and chromatin immunoprecipitation (ChIP). The effects of miR-138-1-3p and PAK5 on HCC sorafenib chemoresistant characteristics were investigated by a xenotransplantation model. Results: We detected significant down-regulation of miR-138-1-3p and up-regulation of PAK5 in HCC sorafenib resistance cell lines. Mechanical studies revealed that miR-138-1-3p reduced the protein expression of PAK5 by directly targeting the 3′-UTR of PAK5 mRNA. In addition, we verified that PAK5 elevated the phosphorylation and nuclear translocation of β-catenin that enhanced the transcriptional activity of multidrug resistance protein ABCB1. Conclusions: PAK5 contributed to the sorafenib chemoresistant characteristics of HCC by activity β-catenin/ABCB1 signaling pathway. Our findings identified the correlation between miR-138-1-3p and PAK5 and the molecular mechanisms of PAK5-mediated HCC sorafenib resistance, which provided a potential therapeutic target for advanced HCC patients.

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