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c-Fos
Terms modified by c-Fos Selected AbstractsFunctional dentate gyrus neurogenesis in a rapid kindling seizure modelEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2006Paul D. Smith Abstract Neurogenesis in the adult mammalian hippocampus resulting in long-term persistence of new neurons with features of capacity for functional activation is recognized. Many stimuli are capable of increasing the rate of neurogenesis, including seizure activity. Whether these insults result in an increased number of new functionally active neurons over and above the baseline rate of neurogenesis is not known. The rapid electrical amygdala kindling (REAK) model of seizures isolates the effects of seizures alone in the absence of neuronal death and the resulting seizures induce expression of c-Fos in the vast majority of dentate gyrus (DG) granule cells. C57BL/6 mice were exposed to REAK then injected with bromodeoxyuridine (BrDU) to label dividing cells, then re-exposed to REAK after a delay period to allow detection of functional activation in new neurons by measurement c-Fos expression in response to seizures. Adult subgranular zone cells migrated into the DG granule cell layer (GCL), assumed a neuronal phenotype and demonstrated seizure-dependent responsiveness. Larger absolute numbers of new neurons demonstrating seizure-dependent activation were found in the GCL of previously kindled mice. Seizures are capable of increasing the number of new neurons with the capacity for functional activation laid down in the postseizure period and incorporated into seizure-activated circuitry. [source] N -methyl- d -aspartate-triggered neuronal death in organotypic hippocampal cultures is endocytic, autophagic and mediated by the c-Jun N-terminal kinase pathwayEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003Tiziana Borsello Abstract Acute excitotoxic neuronal death was studied in rat organotypic hippocampal slices exposed to 100 µmN -methyl- d -aspartate. Fulgurant death of pyramidal neurons occurred in the CA1 and CA3 regions and was already detectable within 2 h of the N-methyl- d -aspartate administration. Morphologically, the neuronal death was neither apoptotic nor necrotic but had the hallmarks of autophagic neuronal death, as shown by acid phosphatase histochemistry in both CA1 and CA3 and by electron microscopy in CA1. The dying neurons also manifested strong endocytosis of horseradish peroxidase or microperoxidase, occurring probably by a fluid phase mechanism, and followed, surprisingly, by nuclear entry. In addition to these autophagic and endocytic characteristics, there were indications that the c-Jun N-terminal kinase pathway was activated. Its target c-Jun was selectively phosphorylated in CA1, CA3 and the dentate gyrus and c-Fos, the transcription of which is under the positive control of c-Jun N-terminal kinase target Elk1, was selectively up-regulated in CA1 and CA3. All these effects, the neuronal death itself and the associated autophagy and endocytosis, were totally prevented by a cell-permeable inhibitor of the interaction between c-Jun N-terminal kinase and certain of its targets. These results show that pyramidal neurons undergoing excitotoxic death in this situation are autophagic and endocytic and that both the cell death and the associated autophagy and endocytosis are under the control of the c-Jun N-terminal kinase pathway. [source] Postnatal handling alters the activation of stress-related neuronal circuitriesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2000István M. Ábrahám Abstract Postnatal handling, as a crucial early life experience, plays an essential role in the development of hypothalamo-pituitary,adrenal axis responses to stress. The impact of postnatal handling on the reactivity of stress-related neuronal circuitries was investigated in animals that were handled for the first 21 days of life and as adults they were exposed to physical (ether) or emotional (restraint) challenge. To assess neuronal activation we relied on the induction of immediate-early gene product c-Fos and analysed its spatial and temporal distribution at various time intervals after stress. Ether and restraint commonly activated parvocellular neurons in the hypothalamic paraventricular nucleus, and resulted in activation of brain areas providing stress-related information to the hypothalamic effector neurons and/or in regions governing autonomic and behavioural responses to stress. Beyond these areas, the strength and timing of c-Fos induction showed stressor specificity in olfactory and septal region, basal ganglia, hypothalamus, hippocampal formation, amygdala and brainstem. Handled rats displayed a lower number of c-Fos-positive cell nuclei and weaker staining intensity than non-handled controls in the hypothalamic paraventricular nucleus, bed nucleus of stria terminalis, central nucleus of amygdala, hippocampus, piriform cortex and posterior division of the cingulum. Significant differences were revealed in timing of c-Fos induction as a function of stressor and early life experience. Together, these data provide functional anatomical evidence that environmental enrichment in the early postnatal period attenuates the reactivity of stress-related neuronal circuitries in the adult rat brain. [source] Inhibition of scratching behaviour caused by contact dermatitis in histidine decarboxylase gene knockout miceEXPERIMENTAL DERMATOLOGY, Issue 3 2005M. Seike Abstract:, A neuronal system dedicated to itch consists of primary afferent and spinothalamic projection neurons. Histamine is thought to be one of the main mediators for the transmission of itch sensation. However, there are little available information on the role of histamine in scratching behaviour and sensory transmission of atopic dermatitis and chronic eczema. In the present study, the role of histamine in scratching behaviour and neural conduction of sensation in the chronic eczema model was investigated by using l-histidine decarboxylase (HDC) gene knockout mice lacking histamine. The chronic contact dermatitis was induced with daily application of diphenylcyclopropenone (DCP) on a hind paw of HDC (+/+) and HDC (,/,) mice for 2 months. The observation of scratching behaviour and the hot-plate test were performed in both mice. Histological studies were performed in the skin and spinal cord tissues. Histological examination revealed that both HDC (+/+) and HDC (,/,) mice displayed the similar extent of inflammatory cell infiltration, hyperplastic epidermis and newly spreading of neuronal processes in the skin tissue. Scratching behaviour was exclusively induced in HDC (+/+) mice, whereas it was barely observed in HDC (,/,) mice. The expression of c-Fos was specifically upregulated in HDC (+/+) mice in lamina I of the spinal dorsal horn following repeated DCP application. Scratching behaviour in chronic contact dermatitis in mice was thought mainly mediated with histamine. The afferent pathway of sensation in chronic contact dermatitis model may connect with the central nervous system through lamina I of the spinal dorsal horn. [source] [Na+]i -induced c-Fos expression is not mediated by activation of the 5,-promoter containing known transcriptional elementsFEBS JOURNAL, Issue 14 2007Mounsif Haloui In vascular smooth muscle cells and several other cell types, inhibition of Na+/K+ -ATPase leads to the expression of early response genes, including c-Fos. We designed this study to examine whether or not a putative Na+i/K+i -sensitive element is located within the c-Fos 5,-UTR from ,,650 to +,103 containing all known response elements activated by ,classic' stimuli, such as growth factors and Ca2+i -raising compounds. In HeLa cells, the highest increment of c-Fos mRNA content was noted after 6 h of Na+/K+ -ATPase inhibition with ouabain that was abolished by actinomycin D, an inhibitor of RNA synthesis. c-Fos protein accumulation in ouabain-treated cells correlated with a gain of Na+i and loss of K+i. Augmented c-Fos expression was also observed under inhibition of Na+/K+ -ATPase in K+ -free medium and in the presence of the Na+ ionophore monensin. The effect of ouabain on c-Fos expression was sharply attenuated under dissipation of the transmembrane Na+ gradient, but was preserved in the presence of Ca2+ chelators and the extracellular regulated kinase inhibitor PD98059, thus indicating an Na+i -mediated, Ca2+i - and extracellular regulated kinase-independent mechanism of gene expression. In contrast to massive c-Fos expression, we failed to detect any effect of ouabain on accumulation of luciferase driven by the c-Fos 5,-UTR. Negative results were also obtained in ouabain-treated vascular smooth muscle cells and C11 Madin,Darby canine kidney cells possessing augmented c-Fos expression. Our results reveal that Na+i -induced c-Fos expression is not mediated by the 5,-UTR containing transcriptional elements activated by growth factors and other ,classic stimuli'. [source] Memory retrieval after contextual fear conditioning induces c-Fos and JunB expression in CA1 hippocampusGENES, BRAIN AND BEHAVIOR, Issue 1 2003T. Strekalova Using specific polyclonal antisera against c-Fos, JunB, c-Jun and JunD, we tried to identify the candidate transcription factors of the immediate early gene family which may contribute to the molecular processes during contextual memory reconsolidation. For that purpose we analyzed the expression of these proteins in the hippocampus after contextual memory retrieval in a mouse model of fear conditioning. A single exposure to a foot shock of 0.8 mA was sufficient to induce robust contextual fear conditioning in C57Bl/6N mice. In these mice context dependent memory retrieval evoked a marked induction of c-Fos and JunB, but not of c-Jun and JunD, in pyramidal CA1 neurons of the dorsal hippocampus. In contrast, mice exposed and re-exposed only to the context, without foot shock, did not show behavioral signs of contextual fear conditioning and exhibited significantly less expression of c-Fos and JunB in CA1 neurons. Mice which received a foot shock but were not re-exposed to the context revealed no immediate early gene induction. These results demonstrate that contextual memory retrieval is associated with de novo synthesis of specific members of the Fos/Jun transcription factor family. Therefore we suggest that these genes may contribute to plasticity and reconsolidation accompanying the retrieval process. The specific activation of CA1 neurons during the retrieval of contextual fear associations supports the postulated concept of a mnemonic role of this hippocampal subsector during the retrieval of contextual informations. [source] Overexpression of Fos-related antigen-1 in head and neck squamous cell carcinomaINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 4 2005Flavia R. R. Mangone Summary The activating protein-1 (AP-1) family of transcription factors has been implicated in the control of proliferation and differentiation of keratinocytes, but its role in malignant transformation is not clear. The aim of this study is to assess the pattern of mRNA expression of jun-fos AP-1 family members in 45 samples of head and neck squamous cell carcinomas (HNSCC) and matched adjacent mucosa by means of Northern blot analysis. Transcripts of all family members were identified, except for JunB that was detected only by means of reverse transcription polymerase chain reaction. Neither c-Fos nor JunD or FosB mRNA differed between tumours and normal tissues. We observed a strong Fos-related antigen-1 (Fra-1) and Fra-2 expression, but only Fra-1 mRNA densitometric values were higher in tumour, compared to normal adjacent mucosa (t -test, P = 0.006). A direct relationship between the positive expression of Fra-1 mRNA, above tumour median, was associated with the presence of compromised lymph nodes (Fischer exact test, P = 0.006). In addition, Fra-1 protein staining was assessed in a collection of 180 tumours and 29 histologically normal samples adjacent to tumours in a tissue array. Weak reactivity, restricted to the basal cell layer, was detected in 79% of tumour adjacent normal tissues, opposed to the intense reactivity of cancer tissues. In the subgroup of oral cancers, we have observed a shift in Fra-1 immunoreactivity, as long as the number of patients in each category, cytoplasmic or nuclear/cytoplasmic staining, was analysed (Fischer exact test, P = 0.0005). Thus, Fra-1 gene induction and accumulation of Fra-1 protein may contribute to the neoplastic phenotype in HNSCC. [source] Reciprocal regulation of transcription factors and PLC isozyme gene expression in adult cardiomyocytesJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 6b 2010Tushi Singal Abstract By employing a pharmacological approach, we have shown that phospholipase C (PLC) activity is involved in the regulation of gene expression of transcription factors such as c-Fos and c-Jun in cardiomyocytes in response to norepinephrine (NE). However, there is no information available regarding the identity of specific PLC isozymes involved in the regulation of c-Fos and c-Jun or on the involvement of these transcription factors in PLC isozyme gene expression in adult cardiomyocytes. In this study, transfection of cardiomyocytes with PLC isozyme specific siRNA was found to prevent the NE-mediated increases in the corresponding PLC isozyme gene expression, protein content and activity. Unlike PLC ,1 gene, silencing of PLC ,1, ,3 and ,1 genes with si RNA prevented the increases in c-Fos and c-Jun gene expression in response to NE. On the other hand, transfection with c-Jun si RNA suppressed the NE-induced increase in c-Jun as well as PLC ,1, ,3 and ,1 gene expression, but had no effect on PLC ,1 gene expression. Although transfection of cardiomyocytes with c-Fos si RNA prevented NE-induced expression of c-Fos, PLC ,1 and PLC ,3 genes, it did not affect the increases in PLC ,1 and PLC ,1 gene expression. Silencing of either c-Fos or c-Jun also depressed the NE-mediated increases in PLC ,1, ,3 and ,1 protein content and activity in an isozyme specific manner. Furthermore, silencing of all PLC isozymes as well as of c-Fos and c-Jun resulted in prevention of the NE-mediated increase in atrial natriuretic factor gene expression. These findings, by employing gene silencing techniques, demonstrate that there occurs a reciprocal regulation of transcription factors and specific PLC isozyme gene expression in cardiomyocytes. [source] Cellular/intramuscular myxoma and grade I myxofibrosarcoma are characterized by distinct genetic alterations and specific composition of their extracellular matrixJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 7 2009Stefan M. Willems Abstract Cellular myxoma and grade I myxofibrosarcoma are mesenchymal tumours that are characterized by their abundant myxoid extracellular matrix (ECM). Despite their histological overlap, they differ clinically. Diagnosis is therefore difficult though important. We investigated their (cyto) genetics and ECM. GNAS1 -activating mutations have been described in intramuscular myxoma, and lead to downstream activation of cFos. KRAS and TP53 mutations are commonly involved in sarcomagenesis whereby KRAS subsequently activates c-Fos. A well-documented series of intramuscular myxoma (three typical cases and seven cases of the more challenging cellular variant) and grade I myxofibrosarcoma (n= 10) cases were karyotyped, analyzed for GNAS1, KRAS and TP53 mutations and downstream activation of c-Fos mRNA and protein expression. ECM was studied by liquid chromatography mass spectrometry and expression of proteins identified was validated by immunohistochemistry and qPCR. Grade I myxofibrosarcoma showed variable, non-specific cyto-genetic aberrations in 83,5% of cases (n= 6) whereas karyotypes of intramuscular myxoma were all normal (n= 7). GNAS1 -activating mutations were exclusively found in 50% of intramuscular myxoma. Both tumour types showed over-expression of c-Fos mRNA and protein. No mutations in KRAS codon 12/13 or in TP53 were detected. Liquid chromatography mass spectrometry revealed structural proteins (collagen types I, VI, XII, XIV and decorin) in grade I myxofibrosarcoma lacking in intramuscular myxoma. This was confirmed by immunohistochemistry and qPCR. Intramuscular/cellular myxoma and grade I myxofibrosarcoma show different molecular genetic aberrations and different composition of their ECM that probably contribute to their diverse clinical behaviour. GNAS1 mutation analysis can be helpful to distinguish intramuscular myxoma from grade I myxofibrosarcoma in selected cases. [source] Mechanistic study of saikosaponin-d (Ssd) on suppression of murine T lymphocyte activationJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2009Vincent Kam Wai Wong Abstract Saikosaponin-d (Ssd) is a triterpene saponin derived from the medicinal plant, Bupleurum falcatum L. (Umbelliferae). Previous findings showed that Ssd exhibits a variety of pharmacological and immunomodulatory activities including anti-inflammatory, anti-bacterial, anti-viral and anti-cancer effects. In the current study we have investigated the effects of Ssd on activated mouse T lymphocytes through the NF-,B, NF-AT and AP-1 signaling pathways, cytokine secretion, and IL-2 receptor expression. The results demonstrated that Ssd not only suppressed OKT3/CD28-costimulated human T cell proliferation, it also inhibited PMA, PMA/Ionomycin and Con A-induced mouse T cell activation in vitro. The inhibitory effect of Ssd on PMA-induced T cell activation was associated with down-regulation of NF-,B signaling through suppression of IKK and Akt activities. In addition, Ssd suppressed both DNA binding activity and the nuclear translocation of NF-AT and activator protein 1 (AP-1) of the PMA/Ionomycin-stimulated T cells. The cell surface markers like IL-2 receptor (CD25) were also down-regulated together with decreased production of pro-inflammatory cytokines of IL-6, TNF-, and IFN-,. These results indicate that the NF-,B, NF-AT and AP-1 (c-Fos) signaling pathways are involved in the T cell inhibition evoked by Ssd, so it can be a potential candidate for further study in treating T cell-mediated autoimmune conditions. J. Cell. Biochem. 107: 303,315, 2009. © 2009 Wiley-Liss, Inc. [source] Ultrasound increased BMP-2 expression via PI3K, Akt, c-Fos/c-Jun, and AP-1 pathways in cultured osteoblastsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2009Chun-Han Hou Abstract It has been shown that ultrasound (US) stimulation accelerates fracture healing in the animal models and in clinical studies. Bone morphogenetic protein (BMP) is a crucial mediator in bone formation during fracture healing. Here we found that US stimulation increased BMP-2 expression but not other BMPs. US induced BMP-2 transcription is mediated by AP-1 element but not estrogen receptor response element and GC-rich Sp1 response element. Pretreatment of osteoblasts with phosphatidylinositol 3-kinase (PI3K) inhibitor (Ly294002) and Akt inhibitor inhibited the potentiating action of US; these results were further substantiated by transfecting with the dominant negative mutants of p85 and Akt. US stimulation increased the phosphorylation of p85 subunit of PI3K and serine 473 of Akt. Transfection of osteoblasts with c-Fos and c-Jun antisense oligonucleotide also reduced US-increased BMP-2 expression. US-increased the binding of c-Fos and c-Jun to the AP-1 element on the BMP-2 promoter and the enhancement of AP-1 luciferase activity was inhibited by Ly294002 and Akt inhibitor. Our results suggest that US increased BMP-2 expression in osteoblasts via the PI3K, Akt, c-Fos/c-Jun, and AP-1 signaling pathway. J. Cell. Biochem. 106: 7,15, 2009. © 2008 Wiley-Liss, Inc. [source] Two modes of ERK activation by TNF in keratinocytes: Different cellular outcomes and bi-directional modulation by vitamin D,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2008Ester Ziv Abstract Inflammation, elicited in the skin following tissue damage or pathogen invasion, may become chronic with deleterious consequences. Tumor necrosis factor (TNF) is a key mediator of cutaneous inflammation and the keratinocyte an important protagonist of skin immunity. Calcitriol, the hormonally active vitamin D metabolite, and its analogs attenuate epidermal inflammation and inhibit the hyperproliferation of keratinocytes associated with the inflammatory disorder, psoriasis. Since activation of extracellular signal-regulated kinase (ERK) promotes keratinocyte proliferation and mediates epidermal inflammation, we studied the effect of calcitriol on ERK activation in HaCaT keratinocytes exposed to the ubiquitous inflammatory cytokine TNF. By using the EGF receptor (EGFR) tyrosine kinase inhibitor, AG1487 and the Src family inhibitor, PP-1, we established that TNF activated ERK in an EGFR and Src dependent and an EGFR and Src independent modes. EGFR dependent activation resulted in the upregulation of the transcription factor, c-Fos, while the EGFR independent activation mode was of a shorter duration, did not affect c-Fos expression but induced IL-8 mRNA expression. Pretreatment with calcitriol, enhanced TNF-induced EGFR-Src dependent ERK activation and tyrosine phosphorylation of the EGFR, but abolished the EGFR-Src independent ERK activation. These effects were mirrored by enhancement of c-Fos and inhibition of IL-8 induction by TNF. Treatment with calcitriol increased the rate of the de-phosphorylation of activated ERK, accounting for the inhibition of EGFR-Src independent ERK activation by TNF. It is possible that effects on the ERK cascade contribute to the effects of calcitriol and its synthetic analogs on cutaneous inflammation and keratinocyte proliferation. J. Cell. Biochem. 104: 606,619, 2008. © 2007 Wiley-Liss, Inc. [source] Age-related differences in MAP kinase activity in VSMC in response to glucose or TNF-,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2003Muyao Li Aortic vascular smooth muscle cells (VSMC) were used to study the effect of age on responses to high glucose concentrations or the cytokine, tumor necrosis factor-alpha (TNF-,). Activator protein-1 (AP-1) binding to DNA increased more in VSMC from old versus young rats (P,<,0.02) and was related to increased expression of its components, c-Fos, Fra-1, and JunD. The relationship to upstream signals, i.e., activities of mitogen-activated protein kinases (MAPK), was studied using antibodies to total and phosphorylated forms of extracellular signal-regulated kinases (ERK), c-Jun N-terminal kinases (JNK) and p38. High glucose and TNF-, increased ERK phosphorylation more in old (P,<,0.05); whereas only TNF-, induced JNK activation in young (P,<,0.04). PD98059, a MEK inhibitor, attenuated AP-1 activation, lowered c-Fos and Fra-1 protein levels and reduced cell number and cells positive for proliferating cell nuclear antigen in old. We concluded that age differentially influenced activation of signaling pathways in VSMC exposed to high glucose or TNF-,. This may contribute to the increased risk for vascular disease associated with aging and diabetes mellitus (DM). J. Cell. Physiol. 197: 418,425, 2003© 2003 Wiley-Liss, Inc. [source] PACAP and C2-ceramide generate different AP-1 complexes through a MAP-kinase-dependent pathway: involvement of c-Fos in PACAP-induced Bcl-2 expressionJOURNAL OF NEUROCHEMISTRY, Issue 4 2006Nicolas Aubert Abstract The neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) inhibits C2-ceramide-induced cell death through blockade of the mitochondrial apoptotic pathway in rat cerebellar granule neurones. However, the gene induction processes and transcription factors involved in the anti-apoptotic effect of PACAP remain unknown. Here, we show that PACAP and C2-ceramide activate activator protein-1 (AP-1) DNA binding in a dose- and time-dependent manner, but generate different AP-1 dimers. Thus, PACAP increased the proportion of c-Fos and Jun D while C2-ceramide increased c-Jun and reduced c-Fos in AP-1 complexes. In addition, PACAP strongly activated c-Fos gene expression while C2-ceramide markedly increased c-Jun phosphorylation. The effect of PACAP on c-Fos expression was blocked by the mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK) inhibitor, U0126, while phosphorylation of c-Jun induced by C2-ceramide was abrogated by the protein phosphatase 2A (PP2A) inhibitor, okadaic acid. Transfection of immature granule cells with c-Fos siRNA, which strongly reduced basal and PACAP-stimulated levels of the protein, totally prevented the stimulatory effect of PACAP on Bcl-2 expression. The present study demonstrates that AP-1 complexes containing c-Fos mediate the effect of PACAP on Bcl-2 gene expression in cerebellar granule neurones. Our data also indicate that different AP-1 dimers are associated with the pro-apoptotic effect of C2-ceramide and the anti-apoptotic effect of PACAP. [source] Overexpression of c-Fos is sufficient to stimulate tyrosine hydroxylase (TH) gene transcription in rat pheochromocytoma PC18 cellsJOURNAL OF NEUROCHEMISTRY, Issue 2 2002Baoyong Sun Abstract The AP1 site within the tyrosine hydroxylase gene proximal promoter is essential for the response of the gene to numerous stimuli. Stimulation of this gene is often associated with induction of the AP1 transcription factor, c-Fos. However, many stimuli activate or induce multiple transcription factors that interact with this AP1 site or other sites within the gene's proximal promoter. Hence, it remains unclear whether c-Fos induction by itself is sufficient to stimulate the tyrosine hydroxylase gene. In this study we produce rat pheochromocytoma PC18 cells that overexpress c-Fos under control of the tet-inducible system. We demonstrate that induction of c-Fos leads to dramatic stimulation of tyrosine hydroxylase gene transcription rate measured using nuclear run-on assays. This stimulation is closely associated quantitatively with the induction of c-Fos and does not apparently require phosphorylation of c-Fos. The response is partially dependent on the AP1 site within the tyrosine hydroxylase proximal promoter. However, the response of the proximal promoter to c-Fos induction is relatively small compared with that of the endogenous gene. Consequently, our results suggest that c-Fos exerts its influence on the tyrosine hydroxylase gene via multiple mechanisms that are dependent and independent of the proximal promoter AP1 site. [source] Mild carbon monoxide exposure impairs the developing auditory system of the ratJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2003Douglas S. Webber Abstract The object of this study was to determine if chronic exposure to mild concentrations of CO in air caused changes in the integrity of the inferior colliculus during the most active period of synaptogenesis/auditory development. We examined all subregions of the inferior colliculus (IC) of rats by immunocytochemical approaches after pups were exposed chronically to CO concentrations of, 0, 12.5, 25, and 50 ppm in air starting at Day 8 through 20,22 days of age. Mother-reared pups were compared to the gastrostomy-reared pups with or without CO exposure for basal neural activity, using c-Fos immunoreactivity as a marker. Half the rats were examined at 27 days of age, 5 days after the end of CO exposure, and the other half were examined 50 days later at 75,77 days of age. In the central nucleus of the IC, the number of cells expressing a basal level of c-Fos was decreased significantly in the CO-exposed animals when compared to controls; however, there was little or no difference in the number of cells expressing c-Fos in the other subregions of the IC. We conclude that the central nucleus of the inferior colliculus is affected selectively by mild CO exposure (0.0012% in air) and that this reduction in neuronal activity persists into adulthood. © 2003 Wiley-Liss, Inc. [source] Hepatocyte growth factor stimulates cell motility in cultures of the striatal progenitor cells ST14AJOURNAL OF NEUROSCIENCE RESEARCH, Issue 5 2003E. Cacci Abstract Hepatocyte growth factor/scatter factor (HGF/SF) is a growth factor with pleiotropic effects on different cell types. It acts as a mitogen and motility factor for many epithelial cells. HGF/SF and its receptor Met are present in the developing and adult mammalian brain and control neuritogenesis of sympathetic and sensory neurons. We report that the striatal progenitor ST14A cells express the Met receptor, which is activated after binding with HGF/SF. The interaction between Met and HGF/SF triggers a signaling cascade that leads to increased levels of c-Jun, c-Fos, and Egr-1 proteins, in agreement with data reported on the signaling events evoked by HGF in other cellular types. We also studied the effects of the exposure of ST14A cells to HGF/SF. By time-lapse photography, we observed that a 24-hr treatment with 50 ng/ml HGF/SF induced modification in cell morphology, with a decrease in cell-cell interactions and increase of cell motility. In contrast, no effect on cell proliferation was observed. To investigate which intracellular pathway is primarily involved we used PD98059 and LY294002, two specific inhibitors of mitogen-activated protein kinase/extracellular signal-regulated kinase (MAP-kinase/ERK-kinase) and phosphoinositide 3-OH kinase (PI3-K), respectively. Cell motility in HGF/SF treated cultures was inhibited by LY294002 but not by PD98059, suggesting that PI3-K plays a key role in mediating the HGF/SF-induced dissociation of ST14A cells. Previous evidence of HGF stimulation of motility in nervous system has been obtained on postmitotic neurons, which have already acquired their specificity. Data reported here of a motogenic response of ST14A cell line, which displays properties of neuronal progenitors, seem of interest because they suggest that HGF could play a role in very early steps of neurogenesis. © 2003 Wiley-Liss, Inc. [source] Ghrelin Receptor Antagonism Decreases Alcohol Consumption and Activation of Perioculomotor Urocortin-Containing NeuronsALCOHOLISM, Issue 9 2010Simranjit Kaur Background:, The current therapies for alcohol abuse disorders are not effective in all patients, and continued development of pharmacotherapies is needed. One approach that has generated recent interest is the antagonism of ghrelin receptors. Ghrelin is a gut-derived peptide important in energy homeostasis and regulation of hunger. Recent studies have implicated ghrelin in alcoholism, showing altered plasma ghrelin levels in alcoholic patients as well as reduced intakes of alcohol in ghrelin receptor knockout mice and in mice treated with ghrelin receptor antagonists. The aim of this study was to determine the neuroanatomical locus/loci of the effect of ghrelin receptor antagonism on alcohol consumption using the ghrelin receptor antagonist, D-Lys3-GHRP-6. Methods:, In Experiment 1, male C57BL/6J mice were injected with saline 3 hours into the dark cycle and allowed access to 15% (v/v) ethanol or water for 2 hours in a 2-bottle choice experiment. On test day, the mice were injected with either saline or 400 nmol of the ghrelin receptor antagonist, D-Lys3-GHRP-6, and allowed to drink 15% ethanol or water for 4 hours. The preference for alcohol and alcohol intake were determined. In Experiment 2, the same procedure was followed as in Experiment 1 but mice were only allowed access to a single bottle of 20% ethanol (v/v), and alcohol intake was determined. Blood ethanol levels were analyzed, and immunohistochemistry for c-Fos was carried out to investigate changes in neural activity. To further elucidate the mechanism by which D-Lys3-GHRP-6 affects alcohol intake, in Experiment 3, the effect of D-Lys3-GHRP-6 on the neural activation induced by intraperitoneal ethanol was investigated. For the c-Fos studies, brain regions containing ghrelin receptors were analyzed, i.e. the perioculomotor urocortin population of neurons (pIIIu), the ventral tegmental area (VTA), and the arcuate nucleus (Arc). In Experiment 4, to test if blood ethanol concentrations were affected by D-Lys3-GHRP-6, blood samples were taken at 2 time-points after D-Lys3-GHRP-6 pretreatment and systemic ethanol administration. Results:, In Experiment 1, D-Lys3-GHRP-6 reduced preference to alcohol and in a follow-up experiment (Experiment 2) also dramatically reduced alcohol intake when compared to saline-treated mice. The resulting blood ethanol concentrations were lower in mice treated with the ghrelin receptor antagonist. Immunohistochemistry for c-Fos showed fewer immunopositive cells in the pIIIu of the antagonist-treated mice but no difference was seen in the VTA or Arc. In Experiment 3, D-Lys3-GHRP-6 reduced the induction of c-Fos by intraperitoneal ethanol in the pIIIu but had no effect in the VTA. In the Arc, there was a significant increase in the number of c-Fos immunopositive cells after D-Lys3-GHRP-6 administration, but the antagonist had no effect on ethanol-induced expression of c-Fos. D-Lys3-GHRP-6-pretreatment also did not affect the blood ethanol concentrations observed after a systemic injection of ethanol when compared to saline-pretreated mice (Experiment 4). Conclusions:, These findings indicate that the action of ghrelin on the regulation of alcohol consumption may occur via the pIIIu. [source] The protective action of scutellarin against immunological liver injury induced by concanavalin A and its effect on pro-inflammatory cytokines in miceJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 1 2007Zheng Huai Tan Scutellarin is a natural compound from a Chinese herb. The purpose of this paper was to study the protective effect of scutellarin on concanavalin A (Con A)-induced immunological liver injury and its effect on liver nuclear factor ,B (NF-,B), tumor necrosis factor , (TNF-,), interferon , (IFN-,), and inducible nitric oxide synthase (iNOS) expression in mice. Mouse liver injury was produced by injection of Con A 25 mg kg,1 via the tail vein. Scutellarin 50 or 100 mg kg,1 was peritoneally administered to mice 9 or 1 h before injection of Con A. The levels of serum alanine aminotransferase (ALT) and asparatate aminotransferase (AST), NO2,/NO3, and TNF - , were determined with biochemical kits, and ELISA using Quantikine Mouse TNF-, kit according the manufacturer's instructions. Liver lesions were examined by light microscope. The expression of TNF-,, IFN-,, iNOS and Fas mRNA in the livers was detected by RT-PCR; and the expression of c-Fos, c-Jun, iNOS and I,B proteins was measured by Western Blotting. As a result, pretreatment with scutellarin 100 mg kg,1 significantly decreased the serum ALT, AST, NO2,/NO3,and TNF-, levels, and also reduced liver lesions induced by Con A. Scutellarin 100 mg kg,1 down-regulated expression of TNF-, and iNOS mRNA, and c-Fos, c-Jun and iNOS protein, while scutellarin enhanced the degradation of I,B, in the livers of mice injected with Con A. The results suggest that scutellarin has a protective action against Con A-induced liver injury in mice, and its active mechanism may be related to the inhibition of the NF-,B-TNF-,-iNOS transduction pathway. [source] Expression of c-Fos in Alko Alcohol Rats Responding for Ethanol in an Operant ParadigmALCOHOLISM, Issue 5 2001Adam Z. Weitemier Background: Identification of the brain regions involved in ethanol administration is important for understanding the neurobiology of ethanol addiction. Animal studies with different brain mapping techniques found that voluntary ethanol self-administration leads to changes in activity of specific brain regions in patterns that only partially overlap with patterns of brain regions affected by involuntary (i.e., experimenter-administered) ethanol administration. As an extension of studies mapping changes in neural activity after voluntary ethanol drinking, this study analyzed expression of the inducible transcription factor c-Fos after ethanol consumption in an operant procedure. Methods: AA (Alko alcohol) rats were trained to operantly respond for water, 0.2% saccharin, 0.2% saccharin/10% (w/v) ethanol, or 10% ethanol in a 30-min limited-access procedure. Animals were allowed to self-administer solutions for at least 40 ethanol response sessions and were killed 1.5 hr after beginning of the last session. Forty-seven brain regions were immunohistochemically analyzed for c-Fos expression. Results: In this paradigm, ethanol dose-dependently increased c-Fos expression in the Edinger-Westphal nucleus (EW) and decreased expression in the dorsal tenia tecta compared with no-ethanol controls. No effects of saccharin on c-Fos expression were found. Conclusions: Our results extend previous findings of preferential sensitivity of EW to alcohol in voluntary self-administration procedures to operant responding for ethanol and warrant further investigation of ethanol's effects on the EW. The finding that ethanol attenuated c-Fos expression in the tenia tecta is novel. Taken together, these findings confirm that voluntary ethanol self-administration leads to changes in activity of a limited number of brain regions with previously unexamined roles in ethanol sensitivity and addiction. [source] Inositol hexaphosphate downregulates both constitutive and ligand-induced mitogenic and cell survival signaling, and causes caspase-mediated apoptotic death of human prostate carcinoma PC-3 cells,MOLECULAR CARCINOGENESIS, Issue 1 2010Mallikarjuna Gu Abstract Constitutively active mitogenic and prosurvival signaling cascades due to aberrant expression and interaction of growth factors and their receptors are well documented in human prostate cancer (PCa). Epidermal growth factor (EGF) and insulin-like growth factor-1 (IGF-1) are potent mitogens that regulate proliferation and survival of PCa cells via autocrine and paracrine loops involving both mitogen-activated protein kinase (MAPK)- and Akt-mediated signaling. Accordingly, here we assessed the effect of inositol hexaphosphate (IP6) on constitutive and ligand (EGF and IGF-1)-induced biological responses and associated signaling cascades in advanced and androgen-independent human PCa PC-3 cells. Treatment of PC-3 cells with 2,mM IP6 strongly inhibited both growth and proliferation and decreased cell viability; similar effects were also observed in other human PCa DU145 and LNCaP cells. IP6 also caused a strong apoptotic death of PC-3 cells together with caspase 3 and PARP cleavage. Mechanistic studies showed that biological effects of IP6 were associated with inhibition of both constitutive and ligand-induced Akt phosphorylation together with a decrease in total Akt levels, but a differential inhibitory effect on MAPKs extra cellular signal-regulated kinase 1/2 (ERK1/2), c- Jun N-terminal protein kinase (JNK1/2), and p38 under constitutive and ligand-activated conditions. Under similar condition, IP6 also inhibited AP-1 DNA-binding activity and decreased nuclear levels of both phospho and total c-Fos and c- Jun. Together, these findings for the first time establish IP6 efficacy in inhibiting aberrant EGF receptor (EGFR) or IGF-1 receptor (IGF-1R) pathway-mediated sustained growth promoting and survival signaling cascades in advanced and androgen-independent human PCa PC-3 cells, which might have translational implications in advanced human PCa control and management. © 2009 Wiley-Liss, Inc. [source] Increased c-Fos protein in the brains of scrapie-infected SAMP8, SAMR1, AKR and C57BL miceNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 5 2002X. Ye Scrapie is a neurodegenerative disease that occurs naturally in sheep and goats. The histopathological changes include vacuolation, neuronal apoptosis and astrocytosis. The mechanisms involved in neuronal apoptosis are still unknown. Recently, we observed that activated p38 immunohistostaining was increased in scrapie-infected mice. In many neurodegenerative diseases, activation of the p38 pathway and of the immediate-early gene termed c-Fos appears to be required for the initiation of apoptosis. There are similarities in histopathological changes seen in scrapie-infected mice and in an uninfected senescence-accelerated mouse strain (SAMP8). This led us to investigate c-Fos protein levels in the brains of both uninfected and scrapie-infected SAMP8, SAMR1, AKR and C57BL mice using immunohistochemical methods. The SAMR1 strain served as a control in that it is a mouse strain that does not show accelerated ageing, but has a background that is similar to the SAMP8 strain. AKR was used because it is one of the progenitor strains of both SAM strains and, finally, C57BL is a completely unrelated strain. The results showed a low basal c-Fos expression in controls and a marked increase in c-Fos staining in scrapie-infected mice. In scrapie-positive mice, c-Fos immunoreactivity was observed in neurones in the cortex, hippocampus, thalamus, hypothalamus, medulla, midbrain, brainstem, paraterminal body, internal capsule and cerebellar Purkinje cells. Immunoreactivity of c-Fos was also observed in astrocytes in many brain areas of scrapie-infected mice, particularly in the hippocampus and cortex. Our results show that normal mouse brain (NMB)-injected AKR and SAMP8 mice had more c-Fos production than NMB-injected SAMR1 or C57BL mice; scrapie-infection induces significant increases in c-Fos immunoreactivity in all four mouse strains. Our study suggests that the increase in c-Fos levels may play a role in the neuronal apoptosis observed in scrapie-infected mice. [source] Activation of the retrotrapezoid nucleus by posterior hypothalamic stimulationTHE JOURNAL OF PHYSIOLOGY, Issue 21 2009Michal G. Fortuna The retrotrapezoid nucleus (RTN) contains chemically defined neurons (ccRTN neurons) that provide a pH-regulated excitatory drive to the central respiratory pattern generator. Here we test whether ccRTN neurons respond to stimulation of the perifornical hypothalamus (PeF), a region that regulates breathing during sleep, stress and exercise. PeF stimulation with gabazine increased blood pressure, phrenic nerve discharge (PND) and the firing rate of ccRTN neurons in isoflurane-anaesthetized rats. Gabazine produced an approximately parallel upward shift of the steady-state relationship between ccRTN neuron firing rate and end-tidal CO2, and a similar shift of the relationship between PND and end-tidal CO2. The central respiratory modulation of ccRTN neurons persisted after gabazine without a change in pattern. Morphine administration typically abolished PND and reduced the discharge rate of most ccRTN neurons (by 25% on average). After morphine administration, PeF stimulation activated the ccRTN neurons normally but PND activation and the central respiratory modulation of the ccRTN neurons were severely attenuated. In the same rat preparation, most (58%) ccRTN neurons expressed c-Fos after exposure to hypercapnic hyperoxia (6,7% end-tidal CO2; 3.5 h; no hypothalamic stimulation) and 62% expressed c-Fos under hypocapnia (,3% end-tidal CO2) after PeF stimulation. Under baseline conditions (,3% end-tidal CO2, hyperoxia, no PeF stimulation) few (11%) ccRTN neurons expressed c-Fos. In summary, most ccRTN neurons are excited by posterior hypothalamic stimulation while retaining their normal response to CNS acidification. ccRTN neurons probably contribute both to the chemical drive of breathing and to the feed-forward control of breathing associated with emotions and or locomotion. [source] Agonistic behavior and electrical stimulation of the antennae induces Fos-like protein expression in the male cricket brainARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 1 2010Kaushik Ghosal Abstract Immediate early genes (IEG) such as c-Fos and Fos-related antigens (FRA) have been used as markers of neuronal activation. In this study, we determined whether the expression of c-Fos/FRAs is increased in the brains of adult male Acheta domesticus crickets following agonistic interactions. We looked for c-Fos/FRA proteins in the brain of un-fought, control male crickets and of dominant and subordinate male crickets sacrificed at different time periods following an agonistic interaction. Using immunoblot analysis, we found four different c-Fos/FRA-like proteins in the adult cricket brain. Continuous agonistic interaction increased c-Fos/FRA protein expression in the brains of subordinate males compared to control and dominant males. In addition, direct electrical stimulation of the male cricket antennae increased c-Fos/FRA-like protein in the brain. We identified the specific brain regions that exhibit c-Fos/FRA-like immunoreactivity in crickets. We detected c-Fos/FRA-like cellular immunoreactivity in different functional regions of the adult brain including the pars intercerebralis, protocerebrum, deutocerebrum, and the cortex of the mushroom bodies. © 2010 Wiley Periodicals, Inc. [source] Oncostatin M,induced CCL2 transcription in osteoblastic cells is mediated by multiple levels of STAT-1 and STAT-3 signaling: An implication for the pathogenesis of arthritisARTHRITIS & RHEUMATISM, Issue 5 2009Sang-Heng Kok Objective To examine the roles of STATs 1 and 3 in CCL2 production in human osteoblastic cells and their influences on arthritis development. Methods The expression of CCL2 in primary human osteoblasts and U2OS human osteoblastic cells was examined by Northern blotting and enzyme-linked immunosorbent assay. The roles of STAT-1/3 and c-Fos were assessed using short hairpin RNAs (shRNA) to silence their functions. Serine phosphorylation of STATs was assessed by Western blotting. Promoter activities of c-Fos and CCL2 were assessed by chloramphenicol acetyltransferase and luciferase assays, respectively. Interactions of STAT-1, STAT-3, and c-Fos with DNA were evaluated by electrophoretic mobility shift assay (EMSA) and immunoprecipitation. The effect of the JAK inhibitor AG-490 on collagen-induced arthritis (CIA) in rats was examined using immunohistochemistry. Results Oncostatin M (OSM) stimulated CCL2 expression in primary human osteoblasts and U2OS cells. In U2OS cells, STAT-1 and STAT-3 were involved in OSM-stimulated CCL2 expression, and both the phosphatidylinositol 3-kinase/Akt and MEK/ERK pathways were implicated in the activation of these STATs. STAT-1 and STAT-3 modulated the expression of c-Fos and directly transactivated the CCL2 promoter. Moreover, EMSA showed formation of a DNA,protein complex containing STAT-1, STAT-3, and interestingly, c-Fos. Immunoprecipitation confirmed the binding between c-Fos and STAT-1/3. Reporter assay revealed synergistic attenuation of CCL2 promoter activity by shRNA targeting of STAT-1, STAT-3, and c-Fos. AG-490 suppressed OSM-stimulated activation of STAT-1/3 and synthesis of CCL2 in vitro and diminished the severity of CIA and the number of CCL2-synthesizing osteoblasts in vivo. Conclusion These findings show that multiple levels of STAT-1/3 signaling modulate OSM-stimulated CCL2 expression in human osteoblastic cells. Clinically, this pathway may be related to the pathogenesis of arthritis. [source] Epigallocatechin-3-gallate diminishes CCL2 expression in human osteoblastic cells via up-regulation of phosphatidylinositol 3-Kinase/Akt/Raf-1 interaction: A potential therapeutic benefit for arthritisARTHRITIS & RHEUMATISM, Issue 10 2008Sze-Kwan Lin Objective To assess the effects of epigallocatechin-3-gallate (EGCG) on oncostatin M (OSM),induced CCL2 synthesis and the associated signaling pathways in human osteoblastic cells. The therapeutic effect of EGCG on collagen-induced arthritis (CIA) in rats was also studied. Methods CCL2 and c-Fos messenger RNA expression was analyzed by Northern blotting. The modulating effects of EGCG on the activation of Raf-1, Akt, and phosphatidylinositol 3-kinase (PI 3-kinase) were examined by coimmunoprecipitation, Western blotting, and PI 3-kinase activity assay. Interactions between c-Fos and CCL2 promoter were evaluated by electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assay. The effect of EGCG on CIA in rats was examined clinically and immunohistochemically. Results EGCG inhibited OSM-stimulated CCL2 expression in primary human osteoblasts and MG-63 cells. In MG-63 cells, EGCG alleviated the OSM-induced phosphorylation of Raf-1 at Ser338 but restored the dephosphorylation of Raf-1 at Ser259. EGCG increased the activity of PI 3-kinase, the level of phosphorylated Akt (Ser473), and binding between Raf-1 and active Akt. EMSA and ChIP assay revealed that EGCG attenuated activator protein 1 (AP-1),CCL2 promoter interaction, possibly by reducing c-Fos synthesis. Codistribution of CD68+ macrophages and CCL2+ osteoblasts in osteolytic areas was obvious in the CIA model. Administration of EGCG markedly diminished the severity of CIA, macrophage infiltration, and the amount of CCL2-synthesizing osteoblasts. Conclusion By stimulating PI 3-kinase activity, EGCG promoted Akt/Raf-1 crosstalk, resulting in decreased AP-1 binding to CCL2 promoter, and finally reduced CCL2 production in osteoblasts. EGCG alleviated the severity of CIA, probably by suppressing CCL2 synthesis in osteoblasts to diminish macrophage infiltration. Our data support the therapeutic potential of EGCG on arthritis. [source] Differential Extracellular Signal-Regulated Kinases 1 and 2 Activation by the Angiotensin Type 1 Receptor Supports Distinct Phenotypes of Cardiac MyocytesBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 5 2007Mark Aplin The biological importance of this, however, remains obscure. Application of the modified analogue [Sar1, Ile4, Ile8]-AngII ([SII] AngII) allowed us to dissect the two pathways of ERK1/2 activation in native cardiac myocytes. Although cytosol-retained, the ,-arrestin2-bound pool of ERK1/2 represents an active signalling component that phosphorylates p90 Ribosomal S6 Kinase, a ubiquitous and versatile mediator of ERK1/2 signal transduction. Moreover, the ,-arrestin2-dependent ERK1/2 signal supports intact proliferation of cardiac myocytes. In contrast to Gq -activated ERK1/2, and in keeping with its failure to translocate to the nucleus, the ,-arrestin2-scaffolded pool of ERK1/2 does not phosphorylate the transcription factor Elk-1, induces no increased transcription of the immediate-early gene c-Fos, and does not entail myocyte hypertrophy. These results clearly demonstrate the biological significance of differential signalling by the AT1R. The opportunity to separate desirable cardiac myocyte division from detrimental hypertrophy holds promise that novel pharmacological approaches will allow targeting of pathway-specific actions. [source] The immediate-early oncoproteins Fra-1, c-Fos, and c-Jun have distinguishable surface behavior and interactions with phospholipidsBIOPOLYMERS, Issue 9 2009María Cecilia Gaggiotti Abstract This work explores the surface properties of the transcription factor Fra-1 and compares them with those of two other immediate early proteins, c-Fos and c-Jun, to establish generalities and differences in the surface behavior and interaction with phospholipids of this type of proteins. We present several experimental clues of the flexible nature of Fra-1, c-Fos, and c-Jun that support sequence-based predictions of their intrinsical disorder. The values of surface parameters for Fra-1 are similar in general to those of c-Fos and c-Jun. However, we find differences in the interactions of the three proteins with phospholipids. The closely related Fra-1 and c-Fos share affinity for anionic lipids but the former has more affinity for a condensed phase and senses a change in DPPC phase, while the latter has more affinity for an expanded phase. These features are in contrast with our previous finding that c-Jun is not selective for phospholipid polar head group or charge. We show here that at least some immediate early transcription factors can interact with membrane phospholipids in a distinguishable manner, and this shall provide a basis for their potential capacity to regulate membrane-mediated cellular processes. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 710,718, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Effects of inactivation-resistant agonists on the signalling, desensitization and down-regulation of bradykinin B2 receptorsBRITISH JOURNAL OF PHARMACOLOGY, Issue 5 2009Marie-Thérčse Bawolak Background and purpose:, A peptide bradykinin (BK) B2 receptor agonist partially resistant to degradation, B-9972, down-regulates this receptor subtype. We have used another recently described non-peptide agonist, compound 47a, as a tool to study further the effects of metabolically more stable and thus persistent, agonists of the BK B2 receptor on signalling, desensitization and down-regulation of this receptor. Experimental approach and key results:, Compound 47a was a partial agonist at the B2 receptor in the human umbilical vein, where it shared with B-9972 a very slow relaxation on washout, and in HEK 293 cell lines expressing tagged forms [myc, green fluorescent protein (GFP)] of the rabbit B2 receptor. Compound 47a desensitized the umbilical vein to BK. In the cellular systems, the inactivation-resistant agonists induced [Ca2+]i transients as brief as those of BK but affected other functions with a longer duration than BK [12 h; receptor endocytosis, endosomal ,-arrestin1/2 translocation, protein kinase C-dependent extracellular signal-regulated kinases (ERK)1/2 phosphorylation and c-Fos expression]. The B2 receptor,GFP was degraded in cells exposed to B-9972 or compound 47a for 12 h. The non-peptide B2 receptor antagonist LF 16-0687 prevented all effects of compound 47a, which were also absent in cells lacking recombinant B2 receptors. Conclusion and implications:, Inactivation-resistant agonists revealed a long-lasting assembly of the agonist,B2 receptor,,-arrestin complexes in endosomal structures and induce ,biased signalling' (in terms of activation of ERK and c-Fos) as a function of time. Further, B-9972 and compound 47a, unlike BK, efficiently down-regulated BK B2 receptors. [source] The HIV protease inhibitor ritonavir synergizes with butyrate for induction of apoptotic cell death and mediates expression of heme oxygenase-1 in DLD-1 colon carcinoma cellsBRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2004Heiko Mühl The protease inhibitor ritonavir is an integral part of current antiretroviral therapy targeting human immunodeficiency virus. Recent studies demonstrate that ritonavir induces apoptotic cell death with high efficiency in lymphoblastoid cell lines. Moreover, ritonavir can suppress activation of the transcription factor nuclear factor- ,B and is an inhibitor of interleukin-1, and tumor necrosis factor- , production in peripheral blood mononuclear cells. Thus, ritonavir appears to have anti-inflammatory properties. In the present study, we investigated in DLD-1 colon carcinoma cell effects of ritonavir on apoptotic cell death and expression of heme oxygenase-1 (HO-1), an anti-inflammatory enzyme that may be critically involved in the modulation of colonic inflammation. Compared to unstimulated control, ritonavir resulted in a moderate increase in the rate of apoptotic cell death as observed after 20 h of incubation. Notably, ritonavir potently synergized with the short-chain fatty acid butyrate for induction of caspase-3-dependent apoptosis in DLD-1 cells. Ritonavir enhanced mRNA and protein expression of HO-1 in DLD-1 cells. Ritonavir-induced HO-1 protein was suppressed by SB203580 or SB202190 and preceded by immediate upregulation of cellular c-Fos and c-Jun protein levels. This process was associated with induction of activator protein-1 as detected by electrophoretic mobility shift analysis. The present data suggest that ritonavir has the potential to curb colon carcinogenesis by reducing cell growth via mechanisms that include apoptosis and by simultaneously modulating colonic inflammation via induction of anti-inflammatory HO-1. British Journal of Pharmacology (2004) 143, 890,898. doi:10.1038/sj.bjp.0706023 [source] | ||||||||||||||||||||||||||||