Systems Toxicology Group
Systems Toxicology Group
Luo Y.,De Montfort University |
Luo Y.,Thomas Jefferson University |
Cheng Z.,De Montfort University |
Dixon C.J.,De Montfort University |
And 4 more authors.
European Journal of Pharmacology | Year: 2011
Agonist-induced internalisation of receptors may lead to the formation of signalling endosomes. There is little evidence relating to whether this occurs to native receptors in non-transformed cells, and no previous studies asking whether this endosomal signalling can promote cell cycle progression in non-transformed cells. We investigated the hypothesis that in primary hepatocytes clathrin-dependent epidermal growth factor (EGF)-induced internalisation of the EGF receptor leads to signalling from endosomal EGF-EGF receptor complexes which may support EGF-stimulated cell cycle progression. We used EGF-stimulation of rat hepatocytes followed by confocal microscopy, and Western blots for phosphoproteins. [3H]thymidine incorporation into DNA was used as a indicator of progression to S-phase. Confocal microscopy demonstrated co-internalisation of EGF, EGF receptors and transferrin into endosomes. Internalisation of EGF/EGF receptor/transferrin was blocked by expression of dominant-negative dynamin, but not by the tyrosine kinase inhibitor AG 1478. Dominant-negative dynamin expression reduced EGF-stimulated extracellular signal-related kinase and Akt signalling, but increased tyrosine phosphorylated EGF receptor. EGF-stimulated cell cycle progression requires stimulation of EGF receptors during an initial period (e.g. 1 h) and also later during a 24 h incubation. EGF receptor internalisation in the presence of AG 1478 followed by removal of the inhibitor resulted in signalling from internalised EGF receptors that is sufficient for the initial stimulation to provide progression to S-phase of the cell cycle. These observations on hepatocytes characterise, for the first time in non-transformed cells, endosomal signalling from internalised EGF receptors, and provide evidence that this endosomal signalling may support the early phase of EGF-stimulated cell cycle progression. © 2010 Elsevier B.V.
Marczylo E.L.,Systems Toxicology Group |
Amoako A.A.,Endocannabinoid Research Group |
Konje J.C.,Endocannabinoid Research Group |
Gant T.W.,Systems Toxicology Group |
And 2 more authors.
Epigenetics | Year: 2012
Recent work has suggested that environmental chemicals, including those contained in cigarette smoke, can have adverse effects on the exposed individuals as well as their future progeny. The mechanisms underlying transmission of environmentally-induced phenotypes through the germ line are not well understood. However, a predominant process appears to be the establishment of permanent heritable epigenetic alterations, and a number of studies have implicated microRNAs in such processes. Here, we show that cigarette smoke induces specific differences in the spermatozoal microRNA content of human smokers compared with non-smokers, and that these altered microRNAs appear to predominantly mediate pathways vital for healthy sperm and normal embryo development, particularly cell death and apoptosis. microRNA-mediated perturbation of such pathways may explain how harmful phenotypes can be induced in the progeny of smokers. © 2012 Landes Bioscience.
Foster C.T.,University of Leicester |
Dovey O.M.,University of Leicester |
Lezina L.,University of Leicester |
Luo J.L.,Systems Toxicology Group |
And 4 more authors.
Molecular and Cellular Biology | Year: 2010
Lysine-specific demethylase 1 (LSD1), which demethylates mono- and dimethylated histone H3-Lys4 as part of a complex including CoREST and histone deacetylases (HDACs), is essential for embryonic development in the mouse beyond embryonic day 6.5 (e6.5). To determine the role of LSD1 during this early period of embryogenesis, we have generated loss-of-function gene trap mice and conditional knockout embryonic stem (ES) cells. Analysis of postimplantation gene trap embryos revealed that LSD1 expression, and therefore function, is restricted to the epiblast. Conditional deletion of LSD1 in mouse ES cells, the in vitro counterpart of the epiblast, revealed a reduction in CoREST protein and associated HDAC activity, resulting in a global increase in histone H3-Lys56 acetylation, but not H3-Lys4 methylation. Despite this biochemical perturbation, ES cells with LSD1 deleted proliferate normally and retain stem cell characteristics. Loss of LSD1 causes the aberrant expression of 588 genes, including those coding for transcription factors with roles in anterior/ posterior patterning and limb development, such as brachyury, Hoxb7, Hoxd8, and retinoic acid receptor γ (RARγ). The gene coding for brachyury, a key regulator of mesodermal differentiation, is a direct target gene of LSD1 and is overexpressed in e6.5 Lsd1 gene trap embryos. Thus, LSD1 regulates the expression and appropriate timing of key developmental regulators, as part of the LSD1/CoREST/HDAC complex, during early embryonic development. © 2010, American Society for Microbiology.
Amoako A.A.,University of Leicester |
Marczylo T.H.,Public Health England |
Marczylo E.L.,Systems Toxicology Group |
Elson J.,The London Clinic |
And 3 more authors.
Human Reproduction | Year: 2013
STUDY QUESTIONWhat are the levels of anandamide (N- arachidonoylethanolamide, AEA) in human seminal plasma and how are these related to abnormal spermatozoa?SUMMARY ANSWERSeminal plasma AEA levels were lower in men with asthenozoospermia and oligoasthenoteratozoospermia compared with normozoospermic men.WHAT IS KNOWN ALREADYAEA, a bioactive lipid, synthesized from membrane phospholipids may signal through cannabinoid receptors (CB1 and CB2) to regulate human sperm functions and male reproduction by modulating sperm motility, capacitation and the acrosome reaction in vitro. Local AEA levels are regulated by the synthetic and degradative enzymes, NAPE-PLD and FAAH, respectively. How the deregulation of this endogenous signalling pathway affects human sperm function(s) is not clear.STUDY DESIGN, SIZE AND DURATIONThis was a cross-sectional study of 86 men presenting at an infertility clinic for semen analysis over a period of 2 years.PARTICIPANTS/MATERIALS, SETTING, METHODSAEA was quantified, by ultra-high performance liquid chromatography-tandem mass spectrometry, in seminal plasma from 86 volunteers. Using qRT-PCR, CB1, CB2, NAPE-PLD and FAAH transcript levels were determined in spermatozoa from men with normozoospermia, asthenozoospermia, oligoasthenoteratozoospermia and teratozoospermia. Normal spermatozoa were exposed in vitro to methanadamide (meth-AEA) to determine its effect on sperm motility, viability and mitochondrial activity.MAIN RESULTS AND THE ROLE OF CHANCESeminal plasma AEA levels (mean ± SEM) were significantly lower in men with asthenozoospermia (0.080 ± 0.01 nM; P < 0.05) or oligoasthenoteratozoospermia (0.083 ± 0.01 nM; P < 0.05) compared with normozoospermic men (0.198 ± 0.03 nM). In addition, the levels of spermatozoal CB1 mRNA were significantly decreased in men with asthenozoospermia (P < 0.001) or oligoasthenoteratozoospermia (P < 0.001) compared with normozoospermic controls. Supra-physiological levels of meth-AEA decreased sperm motility and viability, probably through CB1-mediated inhibition of mitochondrial activity.LIMITATIONS, REASONS FOR CAUTIONThe inhibitory effect of meth-AEA was only shown in vitro and may not reflect what happens in vivo.WIDER IMPLICATIONS OF THE FINDINGSAs the regulation of the endocannabinoid system appears to be necessary for the preservation of normal sperm function and male fertility, there may be implications for the adverse reproductive consequences of marijuana use. Exocannabinoids, such as Δ9-THC, are likely to compete with endocannabinoids at the cannabinoid receptors, upsetting the finely balanced endocannabinoid signalling system. The importance of the endocannabinoid system makes it an attractive target for pharmacological interventions to control male fertility.STUDY FUNDING/COMPETING INTEREST(S)This work was funded in part by miscellaneous educational funds from the University Hospitals of Leicester National Health Services Trust to support the Endocannabinoid Research Laboratory of University of Leicester. The authors declare no competing interests. © The Author 2013.
PubMed | Systems Toxicology Group
Type: Journal Article | Journal: Epigenetics | Year: 2012
Recent work has suggested that environmental chemicals, including those contained in cigarette smoke, can have adverse effects on the exposed individuals as well as their future progeny. The mechanisms underlying transmission of environmentally induced phenotypes through the germ line are not well understood. However, a predominant process appears to be the establishment of permanent heritable epigenetic alterations, and a number of studies have implicated microRNAs in such processes. Here, we show that cigarette smoke induces specific differences in the spermatozoal microRNA content of human smokers compared with non-smokers, and that these altered microRNAs appear to predominantly mediate pathways vital for healthy sperm and normal embryo development, particularly cell death and apoptosis. microRNA-mediated perturbation of such pathways may explain how harmful phenotypes can be induced in the progeny of smokers.