169,901 research outputs found
The lost of Scavenger Receptor B1 by Cigarette Smoke Exposure in Keratinocytes is Driven by H202
No full textThe lost of Scavenger Receptor B1 by Cigarette Smoke
Exposure in Keratinocytes is Driven by H2O2
Giuseppe Valacchi
1
, Claudia Sticozzi
2
, Alessandra Pecorelli
3
, Giuseppe
Belmonte4
, Emanuela Maioli
5
, Beatrice Arezzini
3
, and Concetta Gardi
3
1
Dept. of Evolutionary Biology,
2
Dept. di Ingegneria Meccanica e
Strutturale,
3
Dept of Pathology,
4
Dept of Biomedical
Sciences,
5
Dept of Physiology, University of Siena
Scavenger Receptor B1 (SRB1), also known as HDL receptor, is
involved in cellular cholesterol uptake. Stratum corneoum (SC),
the outermost layer of the skin, is composed for more than 25%
by cholesterol. Several reports support the view that alteration of
SC lipids composition may be the cause of impaired barrier
function which gives rise to several skin diseases. for this reason
the regulation of the genes involved in cholesterol uptake is of
extreme significance for skin health. Being the first shield against
the outdoor insults, the skin is exposed to several noxious
substances and among these is cigarette smoke (CS) which has
been recently associated to various skin pathologies. Using
immunoblotting, immunoprecipitation, RT-PCR, and confocal
microscopy we have demonstrated that the translocation and the
consecutive lost of SRB1 in human keratinocytes after CS
exposure is driven by hydrogen peroxide (H2O2) which derives not
only from the CS gas phase but mainly from the activation of
cellular NADPH oxidase (NOX). This effect was reversed when
the cells were pretreated with NOX inhibitors, catalase, or
superoxide dismutase (SOD) inhibitor. Furthermore, CS caused
the formation of SRB1-aldheydes adducts (Acrolein and 4-
Hydroxynonenal) and the increased of its ubiquitination which is
the cause of SRB1 lost. in conclusion, exposure to CS, through
the production of H2O2, induced post-translational modifications of
SRB1 with the consequence lost of the receptor and this may
contribute to the skin physiology alteration
Nitric Oxide/Cyclic GMP-Dependent Calcium Signalling Mediates IL-6- and TNF-α-Induced Expression of Glial Fibrillary Acid Protein
No full textAstrocyte activation is characterized by hypertrophy with increased glial fibrillary acidic protein (GFAP), whose expression may involve pro-inflammatory cytokines. In this study, the effects of pro-inflammatory IL-6 and TNF-α and anti-inflammatory cytokines IL-4 and IL-10 on nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signalling, intracellular calcium concentration ([Ca2+]i) and GFAP expression were investigated. In human glioblastoma astrocytoma U-373 MG cells, IL-6 and TNF-α, but not IL-4 or IL-10, increased iNOS, cGMP, [Ca2+]i and GFAP expression. The inhibitors of iNOS (1400 W), soluble guanylyl cyclase (ODQ) and IP3 receptors (ryanodine and 2-APB) reversed the increase in cGMP or [Ca2+]i, respectively, and prevented GFAP expression. In rat striatal slices, IL-6 and TNF-α, at variance with IL-4 and IL-10, promoted a concentration-dependent increase in Ca2+ efflux, an effect prevented by 1400 W, ODQ and RY/2APB. These data were confirmed by in vivo studies, where IL-6, TNF-α or the NO donor DETA/NO injected in the striatum of anaesthetised rats increased cGMP levels and increased GFAP expression. The present findings point to NO/cGMP-dependent calcium signalling as part of the mechanism mediating IL-6- and TNF-α-induced GFAP expression. As this process plays a fundamental role in driving neurotoxicity, targeting NO/cGMP-dependent calcium signalling may constitute a new approach for therapeutic interventions in neurological disorders
A nitric oxide/Ca2+/Calmodulin/ERK1/2 mitogen-activated protein kinase pathway is involved in the mitogenic effect of IL-1beta in human astrocytoma cells
No full textBackground and purpose: Evidence is accumulating to support a role for interleukin-1b (IL-1b) in astrocyte proliferation.
However, the mechanism by which this cytokine modulates this process is not fully elucidated.
Experimental approach: In this study we used human astrocytoma U-373MG cells to investigate the role of nitric oxide (NO),
intracellular Ca2þ concentration ([Ca2þ]i), and extracellular signal-regulated protein kinase (ERK) in the signalling pathway
mediating IL-1b-induced astrocyte proliferation.
Key results: Low IL-1b concentrations induced dose-dependent ERK activation which paralleled upregulation of cell division,
whereas higher concentrations gradually reversed both these responses by promoting apoptosis. Pretreatment with the
nonspecific NOS inhibitor, N-o-nitro-l-arginine methyl ester (L-NAME) or the selective iNOS inhibitor, N-[[3-(aminomethyl)-
phenyl]methyl]-ethanimidamide dihydrochloride (1400W), antagonized ERK activation and cell proliferation induced by IL-1b.
Inhibition of cGMP formation by the guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ),
partially inhibited ERK activation and cell division. Functionally blocking Ca2þ release from endoplasmic reticulum with
ryanodine or 2-aminoethoxydiphenylborane (2-APB), inhibiting calmodulin (CaM) activity with N-(6-aminohexyl)-5-chloro-1-
naphthalenesulphonamide hydrochloride (W7) or MAPK kinase activity with 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthiol]
butadiene (U0126) downregulated IL-1b-induced ERK activation as well as cell proliferation. The cytokine induced a
transient and time-dependent increase in intracellular NO levels which preceded elevation in [Ca2þ]i.
Conclusions and implications: These data identified the NO/Ca2þ/CaM/ERK signalling pathway as a novel mechanism
mediating the mitogenic effect of IL-1b in human astrocytes. As astrocyte proliferation is a hallmark of reactive astrogliosis, our
results reveal a new potential target for therapeutic intervention in neuroinflammatory disorders
Rottlerin exhibits antiangiogenic effects in vitro.
No full textRottlerin, a natural product purified from Mallotus philippinensis, has a number of target molecules and biological effects. We recently found that Rottlerin caused growth arrest in MCF-7 breast cancer cells and human immortalized keratinocytes, through inhibition of NFκB and downregulation of cyclin D-1. To evaluate whether this effect could be generalized to primary cells, human microvascular endothelial cells were treated with Rottlerin. In this study, we demonstrated that Rottlerin prevents basal and TNFα-stimulated NFκB nuclear migration and DNA binding also in human microvascular endothelial cell, where NFκB inhibition was accompanied by the downregulation of NFκB target gene products, such as cyclin D-1 and endothelin-1, which are essential molecules for endothelial cell proliferation and survival. Rottlerin, indeed, inhibited human microvascular endothelial cells proliferation and tube formation on Matrigel. Rottlerin also increases cytoplasmic free calcium and nitric oxide levels and downregulates endothelin converting enzyme-1 expression, thus contributing to the drop in endothelin-1 and growth arrest. These results suggest that Rottlerin may prove useful in the development of therapeutic agents against angiogenesis
Rottlerin Exhibits Antiangiogenic Effects In vitro
No full textRottlerin, a natural product purified from Mallotus philippinensis, has a number of target molecules and biological effects. We recently found that Rottlerin caused growth arrest in MCF-7 breast cancer cells and human immortalized keratinocytes, through inhibition of NFκB and downregulation of cyclin D-1. To evaluate whether this effect could be generalized to primary cells, human microvascular endothelial cells were treated with Rottlerin. In this study, we demonstrated that Rottlerin prevents basal and TNFα-stimulated NFκB nuclear migration and DNA binding also in human microvascular endothelial cell, where NFκB inhibition was accompanied by the downregulation of NFκB target gene products, such as cyclin D-1 and endothelin-1, which are essential molecules for endothelial cell proliferation and survival. Rottlerin, indeed, inhibited human microvascular endothelial cells proliferation and tube formation on Matrigel. Rottlerin also increases cytoplasmic free calcium and nitric oxide levels and downregulates endothelin converting enzyme-1 expression, thus contributing to the drop in endothelin-1 and growth arrest. These results suggest that Rottlerin may prove useful in the development of therapeutic agents against angiogenesis. © 2011 John Wiley & Sons A/S
Modulation of scavenger receptor B1 (SRB1) levels in human keratynocites by cigarette smoke The role of H202
No full textThe pathological effects of cigarette smoke (CS) have been extensively documented. The CS produces over 4,000 compounds in gaseous and particulate states that are able to induce oxidative stress to the cells.
Skin acts as a first line of defense against environmental trauma. The upper layer of the skin, the stratum corneum, is composed by a lipid barrier.The alteration of the skin lipids composition by the exposure to environmental stressors can affect the capacity of the SC to protect us from dehydration and external dangers.
Scavenger Receptor B1 (SR-B1) has been shown to be involved in the uptake of cholesterol from HDL to peripheral tissues therefore its role in skin homeostasis is crucial.
In the present work we studied the effects of CS and some of its products such as acrolein, 4HNE and H2O2 on SR-B1 expression in human keratinocytes. CS exposure decreased SR-B1 level and induced the formation of aldehydes adducts.
By contrast, cells treated with several doses of acrolein or 4HNE or H2O2 did not affect SR-B1. The treatment with glucose oxidase induces the same effect of CS as to concern SR-B1 levels and this was reversed by catalase.
In addition, CS induced the activation of NADPH oxidase measured as p67 translocation to the membrane.
The data from this study show the decreased levels of SR-B1 after CS exposure is mainly driven by the production of H2O2 (exogenous and endogenous), this could lead to the disturbance of the skin lipid barrier affecting skin physiology and be a possible cause of disorders such as skin aging and wound healing linked to CS exposure
The lost of scavenger receptor B1 by cigarettes smoke exposure in keratinocytes is driven by H202 (esogenous and endogenous)
No full textCS affects keratinocytes SRB1 expression and localizazion via the production of H202 and formation 4HNE protein adducts
No full textScavenger Receptor B1 (SRB1), also known as HDL receptor, is involved in cellular cholesterol uptake. Stratum corneoum (SC), the outermost layer of the skin, is composed for more than 25% by cholesterol. Several reports support the view that alteration of SC lipids composition may be the cause of impaired barrier function which gives rise to several skin diseases. For this reason the regulation of the genes involved in cholesterol uptake is of extreme significance for skin health. Being the first shield against the outdoor insults, the skin is exposed to several noxious substances and among these is cigarette smoke (CS) which has been recently associated to various skin pathologies. Using immunoblotting, immunoprecipitation, RT-PCR, and confocal microscopy we have demonstrated that the translocation and the consecutive lost of SRB1 in human keratinocytes after CS exposure is driven by hydrogen peroxide (H2O2) which derives not only from the CS gas phase but mainly from the activation of cellular NADPH oxidase (NOX). This effect was reversed when the cells were pretreated with NOX inhibitors, catalase, or superoxide dismutase (SOD) inhibitor. Furthermore, CS caused the formation of SRB1-aldheydes adducts (Acrolein and 4-Hydroxynonenal) and the increased of its ubiquitination which is the cause of SRB1 lost. In conclusion, exposure to CS, through the production of H2O2, induced post-translational modifications of SRB1 with the consequence lost of the receptor and this may contribute to the skin physiology alteration
Cigarette smoke affects SRB1 levels in human keratynocites via H202 production
No full textThe pathological effects of cigarette smoke (CS) have been extensively documented and many diseases such as emphysema and lung cancer are directly linked to the consequences of chronic smoke exposure. The combustion of CS produces over 4,000 different compounds in gaseous and particulate states that are able to induce oxidative stress to the cells exposed to the tobacco smoke. In addition, side stream smoke has been shown to be nearly as toxic as direct stream, therefore CS present two-fold heath problem to both passive and active smokers.
Skin acts as a first line of defense against environmental trauma. The upper layer of the skin, the stratum corneum (SC), is composed by lipid barrier that contains unsaturated lipids that are susceptible to oxidation. The alteration of the skin lipids composition by the exposure to environmental stressors such as CS can affect the capacity of the SC to protect us from dehydration and external dangers.
Scavenger Receptor B1 (SR-B1), one of the large family of scavenger receptors, has been shown to be involved in the uptake of cholesterol from HDL to peripheral tissues via apo A-1 mediated processes and also to be important in the delivery of tocopherol to the cells, therefore its role in skin homeostasis is crucial.
In the present studies the effects of CS and of products related to CS such as acrolein, 4HNE and H2O2 on SR-B1 expression in human keratinocytes were assessed. CS exposure induced a significant decrease of SR-B1 expression and the formation of acrolein and 4NHE protein adducts.
On the other hand, cells treated with several doses of acrolein or 4HNE or H2O2 did not affect SR-B1 levels. The treatment with glucose oxidase induces the same effect of CS as to concern SR-B1 levels and this was reversed when cells were treated with catalase.
In addition, CS induced the activation of NADPH oxidase measured as p67 translocation from the cytoplasm to the membrane.
The data from this study show that CS decreases the levels of SR-B1 in human keratinocytes and this effect is mainly driven by the production of H2O2 (exogenous and endogenous). The decrease of SR-B1 could lead to the disturbance of the skin lipid barrier affecting skin physiology and be a possible cause to skin disorders such as skin aging and wound healing linked to CS exposure
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