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British Journal of Pharmacology and... Dec 1951
Topics: Blood Pressure; Blood Pressure Determination; Veratrum Alkaloids
PubMed: 14904893
DOI: 10.1111/j.1476-5381.1951.tb00679.x -
Development (Cambridge, England) Oct 2012Continuous neurogenesis in the adult nervous system requires a delicate balance between proliferation and differentiation. Although Wnt/β-catenin and Hedgehog...
Continuous neurogenesis in the adult nervous system requires a delicate balance between proliferation and differentiation. Although Wnt/β-catenin and Hedgehog signalling pathways are thought to share a mitogenic function in adult neural stem/progenitor cells, it remains unclear how they interact in this process. Adult amphibians produce retinal neurons from a pool of neural stem cells localised in the ciliary marginal zone (CMZ). Surprisingly, we found that perturbations of the Wnt and Hedgehog pathways result in opposite proliferative outcomes of neural stem/progenitor cells in the CMZ. Additionally, our study revealed that Wnt and Hedgehog morphogens are produced in mutually exclusive territories of the post-embryonic retina. Using genetic and pharmacological tools, we found that the Wnt and Hedgehog pathways exhibit reciprocal inhibition. Our data suggest that Sfrp-1 and Gli3 contribute to this negative cross-regulation. Altogether, our results reveal an unexpected antagonistic interplay of Wnt and Hedgehog signals that may tightly regulate the extent of neural stem/progenitor cell proliferation in the Xenopus retina.
Topics: Animals; Animals, Genetically Modified; Cell Proliferation; Drug Antagonism; Embryo, Nonmammalian; Enzyme Inhibitors; Hedgehog Proteins; Indoles; Models, Biological; Organogenesis; Oximes; Receptor Cross-Talk; Retina; Teratogens; Veratrum Alkaloids; Wnt Signaling Pathway; Xenopus laevis
PubMed: 22899850
DOI: 10.1242/dev.079582 -
Cells Jul 2020In the liver, energy homeostasis is mainly regulated by mechanistic target of rapamycin (mTOR) signalling, which influences relevant metabolic pathways, including lipid...
In the liver, energy homeostasis is mainly regulated by mechanistic target of rapamycin (mTOR) signalling, which influences relevant metabolic pathways, including lipid metabolism. However, the Hedgehog (Hh) pathway is one of the newly identified drivers of hepatic lipid metabolism. Although the link between mTOR and Hh signalling was previously demonstrated in cancer development and progression, knowledge of their molecular crosstalk in healthy liver is lacking. To close this information gap, we used a transgenic mouse model, which allows hepatocyte-specific deletion of the Hh pathway, and in vitro studies to reveal interactions between Hh and mTOR signalling. The study was conducted in male and female mice to investigate sexual differences in the crosstalk of these signalling pathways. Our results reveal that the conditional Hh knockout reduces mitochondrial adenosine triphosphate (ATP) production in primary hepatocytes from female mice and inhibits autophagy in hepatocytes from both sexes. Furthermore, in vitro studies show a synergistic effect of cyclopamine and rapamycin on the inhibition of mTor signalling and oxidative respiration in primary hepatocytes from male and female C57BL/6N mice. Overall, our results demonstrate that the impairment of Hh signalling influences mTOR signalling and therefore represses oxidative phosphorylation and autophagy.
Topics: Adenosine Triphosphate; Animals; Autophagy; Drug Synergism; Energy Metabolism; Female; Gene Deletion; Hedgehog Proteins; Hepatocytes; Lipid Metabolism; Liver; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Oxidative Phosphorylation; Sex Factors; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Veratrum Alkaloids
PubMed: 32751882
DOI: 10.3390/cells9081817 -
Japanese Journal of Pharmacology Jan 1991Regional monoamine assays revealed that during veratramine-induced myoclonic movements, the contents of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid...
Regional monoamine assays revealed that during veratramine-induced myoclonic movements, the contents of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in the cerebral cortex were reduced with a slight increase in dopamine metabolites in the midbrain and brainstem. A similar tendency to decrease 5-HT and 5-HIAA contents was observed in the hypothalamus and hippocampus without increase in the contents of dopamine and its metabolites. Norepinephrine levels were not modified in any brain region at any time after the administration of the veratrum alkaloid. It was found that the veratramine evoked 3H-5-HT release from the frontal cortical slices was Ca+(+)-independent and persistent, and it continued approximately 20 min after the 2-min exposure to veratramine. The uptake of 3H-5-HT into the frontal cortical slices was inhibited competitively by veratramine. These results suggest that veratramine is both a releaser and uptake inhibitor of 5-HT and that the veratramine-induced involuntary movements may be mediated by serotonergic hyperfunction.
Topics: 3,4-Dihydroxyphenylacetic Acid; Animals; Brain; Dopamine; Homovanillic Acid; Hydroxyindoleacetic Acid; Male; Mice; Mice, Inbred Strains; Myoclonus; Norepinephrine; Serotonin; Syndrome; Tritium; Veratrum Alkaloids
PubMed: 1710298
DOI: 10.1254/jjp.55.139 -
Proceedings of the National Academy of... Dec 1982The aim of the present study was to assess whether endogenous and newly synthesized glutamate can be released from differentiating cultured cerebellar granule cells in a...
The aim of the present study was to assess whether endogenous and newly synthesized glutamate can be released from differentiating cultured cerebellar granule cells in a way compatible with a neurotransmitter role. Granule cells from 8-day-old rat cerebella were grown in basal Eagle's medium with 10% fetal calf serum for 2-12 days in vitro (DIV), then washed with Krebs-Ringer medium, and labeled for 45 min with tracer amounts of radioactive glutamine. Subsequently, the release of endogenous glutamate and of newly formed radioactive glutamate was measured in basal conditions and upon depolarization with elevated K(+) concentration or veratridine. At 2 DIV, the release of endogenous and newly synthesized glutamate evoked by high K(+) concentration was small and Ca(2+) independent, but it progressively and steadily increased (up to 8- to 10-fold) and became Ca(2+) dependent (up to 80-85%) at later stages (4, 8, and 12 DIV). Veratridine was almost ineffective with cells at 2 DIV but greatly increased glutamate release (endogenous and neosynthesized) at 8 DIV, and its action was totally antagonized by tetrodotoxin. The level and synthesis of glutamate remained fairly constant in cells from 2 to 12 DIV. gamma-Aminobutyric acid synthesis from radioactive glutamine was about 3% of that of glutamate, and gamma-aminobutyric acid release (endogenous and neosynthesized) was not measurable. Aspartate synthesis was about 10% of that of glutamate, and the high K(+) concentration-evoked release of this amino acid was modest and scarcely affected by Ca(2+). Neither high K(+) concentration nor veratridine was able to induce glutamate release from confluent cerebellar astrocyte cultures at 14 DIV, although the level and synthesis of the amino acid were comparable to those in granule cells. In conclusion, the data show that a stimulus-coupled release of endogenous and neosynthesized glutamate is progressively expressed by cerebellar granule cells differentiating in culture, and this strongly supports the concept that glutamate is the neurotransmitter of these cells.
Topics: Animals; Astrocytes; Cell Differentiation; Cells, Cultured; Cerebellum; Glutamates; Interneurons; Membrane Potentials; Neurotransmitter Agents; Rats; Veratridine
PubMed: 6130529
DOI: 10.1073/pnas.79.24.7919 -
Harmful Algae Mar 2021Marine biotoxins accumulating in seafood products pose a risk to human health. These toxins are often potent in minute amounts and contained within complex matrices;...
Marine biotoxins accumulating in seafood products pose a risk to human health. These toxins are often potent in minute amounts and contained within complex matrices; requiring sensitive, reliable, and robust methods for their detection. The mouse neuroblastoma (Neuro-2a) cytotoxicity assay (N2a-assay) is a sensitive, high-throughput, in vitro method effective for detecting sodium channel-specific marine biotoxins. The N2a-assay can be conducted to distinguish between specific effects on voltage-gated sodium (Na) channels, caused by toxins that activate (e.g., ciguatoxins (CTXs), brevetoxins (PbTxs)) or block (e.g., tetrodotoxins, saxitoxins) the target Na. The sensitivity and specificity of the assay to compounds activating the Na are achieved through the addition of the pharmaceuticals ouabain (O) and veratridine (V). However, these compounds can be toxic to Neuro-2a cells and their application at insufficient or excessive concentrations can reduce the effectiveness of this assay for marine toxin detection. Therefore, during growth incubation, Neuro-2a cells were exposed to O and V, and surviving cells exhibiting a lower sensitivity to O and V (OV-LS) were propagated. OV-LS Neuro-2a cells were selected for 60-80% survival when exposed to 0.22/0.022 mM O/V during the cytotoxicity assay. At these conditions, OV-LS N2a cells demonstrated a 3.5-fold higher survival rate 71% ± 7.9 SD (n = 232), and lower sensitivity to O/V, compared to the original Neuro-2a cells 20% ± 9.0 SD (n = 16). Additionally, OV-LS N2a cells were 1.3-2.6-fold more sensitive for detecting CTX3C 1.35 pg/ml, CTX1B 2.06 pg/ml, and PbTx-3 3.04 ng/ml compared to Neuro-2a cells using 0.1/0.01 mM O/V. Detection of CTX3C in a complex fish matrix using OV-LS cells was 0.0048 pg CTX3C/mg fish tissue equivalent. This work shows the potential for a significant improvement in sensitivity for CTX3C, CTX1B, and PbTx-3 using the OV-LS N2a-assay.
Topics: Animals; Cell Line, Tumor; Ciguatoxins; Marine Toxins; Neuroblastoma; Ouabain; Oxocins; Veratridine
PubMed: 33980434
DOI: 10.1016/j.hal.2021.101994 -
American Journal of Physiology. Renal... Nov 2015Hedgehog (Hh) is an evolutionary conserved signaling pathway that has important functions in kidney morphogenesis and adult organ maintenance. Recent work has shown that...
Hedgehog (Hh) is an evolutionary conserved signaling pathway that has important functions in kidney morphogenesis and adult organ maintenance. Recent work has shown that Hh signaling is reactivated in the kidney after injury and is an important mediator of progressive fibrosis. Pericytes and fibroblasts have been proposed to be the principal cells that respond to Hh ligands, and pharmacological attenuation of Hh signaling has been considered as a possible treatment for fibrosis, but the effect of Hh inhibition on tubular epithelial cells after kidney injury has not been reported. Using genetically modified mice in which tubule-derived hedgehog signaling is increased and mice in which this pathway is conditionally suppressed in pericytes that express the proteoglycan neuron glial protein 2 (NG2), we found that suppression of Hh signaling is associated with decreased macrophage infiltration and tubular proliferation but also increased tubular apoptosis, an effect that correlated with the reduction of tubular β-catenin activity. Collectively, our data suggest a complex function of hedgehog signaling after kidney injury in initiating both reparative and proproliferative, prosurvival processes.
Topics: Acute Kidney Injury; Animals; Antigens; Apoptosis; Cell Proliferation; Cell Survival; Disease Models, Animal; Hedgehog Proteins; Kidney Tubules; Kruppel-Like Transcription Factors; Macrophages; Male; Mice, Inbred C57BL; Mice, Transgenic; Nerve Tissue Proteins; Pericytes; Proteoglycans; Receptors, G-Protein-Coupled; Signal Transduction; Smoothened Receptor; Ureteral Obstruction; Veratrum Alkaloids; Zinc Finger Protein GLI1; beta Catenin
PubMed: 26290370
DOI: 10.1152/ajprenal.00232.2015 -
Developmental Biology Mar 2003Although the development of the digestive system of humans and vertebrate model organisms has been well characterized, relatively little is known about how the zebrafish...
Although the development of the digestive system of humans and vertebrate model organisms has been well characterized, relatively little is known about how the zebrafish digestive system forms. We define developmental milestones during organogenesis of the zebrafish digestive tract, liver, and pancreas and identify important differences in the way the digestive endoderm of zebrafish and amniotes is organized. Such differences account for the finding that the zebrafish digestive system is assembled from individual organ anlagen, whereas the digestive anlagen of amniotes arise from a primitive gut tube. Despite differences of organ morphogenesis, conserved molecular programs regulate pharynx, esophagus, liver, and pancreas development in teleosts and mammals. Specifically, we show that zebrafish faust/gata-5 is a functional ortholog of gata-4, a gene that is essential for the formation of the mammalian and avian foregut. Further, extraembryonic gata activity is required for this function in zebrafish as has been shown in other vertebrates. We also show that a loss-of-function mutation that perturbs sonic hedgehog causes defects in the development of the esophagus that parallel those associated with targeted disruption of this gene in mammals. Perturbation of sonic hedgehog also affects zebrafish liver and pancreas development, and these effects occur in a reciprocal fashion, as has been described during mammalian liver and ventral pancreas development. Together, these data define aspects of digestive system development necessary for the characterization of zebrafish mutants. Given the similarities of teleost and mammalian digestive physiology and anatomy, these findings have implications for developmental and evolutionary studies as well as research of human diseases, such as diabetes, liver cirrhosis, and cancer.
Topics: Alleles; Animals; Cell Polarity; Digestive System; Embryo, Nonmammalian; Esophagus; Ethanol; Gene Expression Regulation, Developmental; Genetic Markers; Hedgehog Proteins; Liver; Morphogenesis; Mutation; Pancreas; Pharynx; RNA, Messenger; Signal Transduction; Trans-Activators; Transcription Factors; Veratrum Alkaloids; Zebrafish; Zebrafish Proteins
PubMed: 12618131
DOI: 10.1016/s0012-1606(02)00034-9 -
Neurology India 2012Hedgehog/Gli1 (HH/Gli1) pathway plays an important role in the patterning and development of the central nervous system during embryogenesis. Recent data have shown its...
BACKGROUND
Hedgehog/Gli1 (HH/Gli1) pathway plays an important role in the patterning and development of the central nervous system during embryogenesis. Recent data have shown its potential involvement in a subset of human gliomas and inhibition of the pathway resulted in tumor suppression in both in vitro and in vivo studies. The underlying mechanisms of tumor suppression, however, remain to be fully elucidated.
MATERIALS AND METHODS
Gli1 expression was investigated in 60 surgically resected glioma tissues (World Health Organization (WHO) III-IV).
RESULTS
Gli1 was expressed in 43 gliomas with high Gli1 expression in nine cases, moderate expression in 21 cases, and low expression in 13 cases. Additionally, microvessel counts were higher in Gli1 positive gliomas than those in Gli1 negative gliomas. Gli1 expression in gliomas was positively correlated with microvessel density (MVD). To explore the molecular mechanisms of the phenotypic changes, we performed quantitative real-time polymerase chain reaction (PCR) and Western blot analysis to monitor the changes of a series of genes, which play critical roles in the regulation of glioma angiogenesis. In conclusion, HH/Gli1 pathway inhibition resulted in down-regulation of vascular endothelial growth factor (VEGF), matrix metalloproteinase 2 (MMP2), and matrix metalloproteinase 9 (MMP9) expressions, whereas this pathway activation led to up-regulation of VEGF, MMP2, and MMP9 expressions. These molecular changes of the HH/Gli1 pathway inhibited by indirect drug approach were consistent with Gli1 RNA-interference (RNAi) in glioma cell lines.
CONCLUSION
Our findings demonstrated that the aberrantly active HH/Gli1 pathway contributed to angiogenesis in part through induction of VEGF, MMP2, and MMP9.
Topics: Brain Neoplasms; Cell Line, Tumor; Enzyme Inhibitors; Female; Gene Expression Regulation, Neoplastic; Glioma; Hedgehog Proteins; Humans; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Neovascularization, Pathologic; Patched Receptors; Platelet Endothelial Cell Adhesion Molecule-1; RNA Interference; RNA, Messenger; Receptors, Cell Surface; Signal Transduction; Statistics, Nonparametric; Transcription Factors; Vascular Endothelial Growth Factor A; Veratrum Alkaloids; Zinc Finger Protein GLI1
PubMed: 23287320
DOI: 10.4103/0028-3886.105192 -
PloS One 2011Sonic hedgehog (Shh) signaling plays a crucial role in growth and patterning during embryonic development, and also in stem cell maintenance and tissue regeneration in...
BACKGROUND
Sonic hedgehog (Shh) signaling plays a crucial role in growth and patterning during embryonic development, and also in stem cell maintenance and tissue regeneration in adults. Aberrant Shh pathway activation is involved in the development of many tumors, and one of the most affected Shh signaling steps found in these tumors is the regulation of the signaling receptor Smoothened by the Shh receptor Patched. In the present work, we investigated Patched activity and the mechanism by which Patched inhibits Smoothened.
METHODOLOGY/PRINCIPAL FINDINGS
Using the well-known Shh-responding cell line of mouse fibroblasts NIH 3T3, we first observed that enhancement of the intracellular cholesterol concentration induces Smoothened enrichment in the plasma membrane, which is a crucial step for the signaling activation. We found that binding of Shh protein to its receptor Patched, which involves Patched internalization, increases the intracellular concentration of cholesterol and decreases the efflux of a fluorescent cholesterol derivative (BODIPY-cholesterol) from these cells. Treatment of fibroblasts with cyclopamine, an antagonist of Shh signaling, inhibits Patched expression and reduces BODIPY-cholesterol efflux, while treatment with the Shh pathway agonist SAG enhances Patched protein expression and BODIPY-cholesterol efflux. We also show that over-expression of human Patched in the yeast S. cerevisiae results in a significant boost of BODIPY-cholesterol efflux. Furthermore, we demonstrate that purified Patched binds to cholesterol, and that the interaction of Shh with Patched inhibits the binding of Patched to cholesterol.
CONCLUSION/SIGNIFICANCE
Our results suggest that Patched may contribute to cholesterol efflux from cells, and to modulation of the intracellular cholesterol concentration. This activity is likely responsible for the inhibition of the enrichment of Smoothened in the plasma membrane, which is an important step in Shh pathway activation.
Topics: Animals; Biological Transport; Cell Membrane; Cholesterol; Hedgehog Proteins; Humans; Mice; NIH 3T3 Cells; Patched Receptors; Receptors, Cell Surface; Receptors, G-Protein-Coupled; Saccharomyces cerevisiae; Signal Transduction; Smoothened Receptor; Veratrum Alkaloids
PubMed: 21931618
DOI: 10.1371/journal.pone.0023834