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- Johnson, Magnus S.C. 1969, et al.
(författare)
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Interaction of scavenger receptor class B type I with peroxisomal targeting receptor Pex5p.
- 2003
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Ingår i: Biochemical and biophysical research communications. - 0006-291X. ; 312:4, s. 1325-34
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Tidskriftsartikel (refereegranskat)abstract
- Scavenger receptor class B type I (SR-BI) is an HDL receptor that mediates selective HDL lipid uptake. Peroxisomes play an important role in lipid metabolism and peroxisomal targeting signal type 1 (PTS1)-containing proteins are translocated to peroxisomes by the peroxisomal targeting import receptor, Pex5p. We have previously identified a PTS1 motif in the intracellular domain of rat SR-BI. Here, we examine the possible interaction between Pex5p and SR-BI. Expression of a Flag-tagged intracellular domain of SR-BI resulted in translocation to the peroxisome as demonstrated by double labeling with anti-Flag IgG and anti-catalase IgG analyzed by confocal microscopy. Immunoprecipitation experiments with anti-SR-BI antibody showed that Pex5p co-precipitated with SR-BI. However, when an antibody against Pex5p was used for immunoprecipitation, only the 57kDa, non-glycosylated form, of SR-BI co-precipitated. We conclude that the PTS1 domain of SR-BI is functional and can mediate peroxisomal interaction via Pex5p, in vitro.
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| 2. |
- Svensson, Per-Arne, 1969, et al.
(författare)
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Major role of HSP70 as a paracrine inducer of cytokine production in human oxidized LDL treated macrophages.
- 2006
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Ingår i: Atherosclerosis. - : Elsevier BV. - 0021-9150. ; 185:1, s. 32-8
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Tidskriftsartikel (refereegranskat)abstract
- Lipid accumulation and inflammation are key hallmarks of the atherosclerotic plaque and macrophage uptake of oxidized low-density lipoprotein (oxLDL) is believed to drive these processes. Initial experiments show that supernatants from oxLDL treated macrophages could induce IL-1beta production in naïve macrophages. To search for potential paracrine mediators that could mediate this effect a DNA microarray scan of oxLDL treated human macrophages was performed. This analysis revealed that oxLDL induced activation of heat shock protein (HSP) expression. HSPs have been implicated in the development of atherosclerosis, but the exact mechanisms for this is unclear. Extracellular heat shock protein 70 (HSP70) has been shown to elicit a pro-inflammatory cytokine response in monocytes and could therefore be a potential paracrine pro-inflammatory mediator. After 24 h of oxLDL treatment there was a significant increase of HSP70 concentrations in supernatants from oxLDL treated macrophages (oxLDLsup) compared to untreated controls (P<0.05). OxLDLsup could induce both interleukin (IL)-1beta and IL-12 secretion in naïve macrophages. We also demonstrate that the effect of oxLDLsup on cytokine production and release could be blocked by inhibition of HSP70 transcription or secretion or by the use of HSP70 neutralizing antibodies. This suggests that extracellular HSP70 can mediate pro-inflammatory changes in macrophages in response to oxLDL.
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| 3. |
- Åberg, N David, 1970, et al.
(författare)
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Insulin-like growth factor-I increases astrocyte intercellular gap junctional communication and connexin43 expression in vitro.
- 2003
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Ingår i: Journal of neuroscience research. - : Wiley. - 0360-4012. ; 74:1, s. 12-22
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Tidskriftsartikel (refereegranskat)abstract
- Connexin43 (cx43) forms gap junctions in astrocytes, and these gap junctions mediate intercellular communication by providing transport of low-molecular-weight metabolites and ions. We have recently shown that systemic growth hormone increases cx43 in the brain. One possibility was that local brain insulin-like growth factor-I (IGF-I) could mediate the effect by acting directly on astrocytes. In the present study, we examined the effects of direct application of recombinant human IGF-I (rhIGF-I) on astrocytes in primary culture concerning cx43 protein expression and gap junctional communication (GJC). After 24 hr of stimulation with rhIGF-I under serum-free conditions, the GJC and cx43 protein were analyzed. Administration of 30 ng/ml rhIGF-I increased the GJC and the abundance of cx43 protein. Cell proliferation of the astrocytes was not significantly increased by rhIGF-I at this concentration. However, a higher concentration of rhIGF-I (150 ng/ml) had no effect on GJC/cx43 but increased cell proliferation. Because of the important modulatory role of IGF binding proteins (IGFBPs) on IGF-I action, we analyzed IGFBPs in conditioned media. In cultures with a low abundance of IGFBPs (especially IGFBP-2), the GJC response to 30 ng/ml rhIGF-I was 81%, compared with the average of 25%. Finally, as a control, insulin was given in equimolar concentrations. However, GJC was not affected, which suggests that rhIGF-I acted via IGF-I receptors. In summary, the data show that rhIGF-I may increase GJC/cx43, whereas a higher concentration of rhIGF-I--at which stimulation of proliferation occurred--did not affect GJC/cx43. Furthermore, IGFBP-2 appeared to modulate the action of rhIGF-I on GJC in astrocytes by a paracrine mechanism.
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| 5. |
- Chalise, Jaya Prakash, et al.
(författare)
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IDO1 and TGF- 1 β mediate protective effects of IFN-α in antigen-induced arthritis
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Interferon-α (IFN-α) prevents antigen-induced arthritis (AIA) in mice by an unknown mechanism. Indoleamine 2, 3 dioxygenase 1 (IDO1) is an immunoregulator via enzymatic as well as signalling activity, which can be activated by TGF-β and further mediated via non canonical NF-κB signalling. We here investigated whether IDO1 and TGF-β are involved in IFN-α protective effects in AIA. Arthritis was induced in wt, Ido1-/- or Ifnar-/- mice, treated or not with IFN-α or kynurenine, the main IDO1 product, and antibodies neutralizing TGF-β or 1-methyltryptophan (1-MT), an inhibitor of IDO1 catalytic activity. IDO1 expression and enzymatic activity were determined by RT-PCR and HPLC, respectively. Proliferation was measured by 3H-Thymidine incorporation. Non-canonical NF-κB signalling was evaluated by ELISA and Western blot in plasmacytoid DCs (pDCs) from treated mice. Protective effects of IFN-α in AIA were associated with increased IDO1 expression and kynurenine production in spleen cells, particularly at the time of mBSA sensitization. Lack of IDO1 ablated IFN-α protection and kynurenine prevented AIA in an IFNAR-independent manner. The IDO1 catalytic activity was crucial for IFN-α effects at the sensitization but not effector phase of AIA. The disease effector phase in mice treated with IFN-α was instead characterized by sustained IDO1 and TGF-β expression and activation of the noncanonical NF-κB pathway in pDCs. IFN-α protective effects in AIA involves IDO1 enzymatic and signalling activity in the disease sensitization and effector phase, respectively. Kynurenine, the main IDO1 metabolite, can be used as an alternative treatment to IFN-α in protecting mice from AIA.
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| 8. |
- Holmgren, Per, et al.
(författare)
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Enantioselective analysis of citalopram and its metabolites in postmortem blood and genotyping for CYD2D6 and CYP2C19
- 2004
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Ingår i: Journal of Analytical Toxicology. - : Oxford University Press (OUP). - 0146-4760 .- 1945-2403. ; 28:2, s. 94-104
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Tidskriftsartikel (refereegranskat)abstract
- Citalopram, a selective serotonin reuptake inhibitor, is one of the most commonly found drugs in Swedish forensic autopsy cases. Citalopram is a racemic drug with 50:50 of the S- and R- enantiomers. Enantioselective analysis of citalopram and its metabolites desmethylcitalopram and didesmethylcitalopram were performed in femoral blood from 53 autopsy cases by a chiral high-performance liquid chromatography (HPLC) method. The mean (± standard deviation) S/R ratio for citalopram was 0.67 ± 0.25 and for desmethylcitalopram, 0.68 ± 0.20. We found increasing S/R ratios with increasing concentrations of citalopram. We also found that high citalopram S/R ratios were associated with a high parent drug-to-metabolite ratio and may be an indicator of recent intake. Citalopram is metabolized by cytochrome P450 (CYP) 3A4, 2C19, and 2D6. Genotyping for the polymorphic CYP2C19 and CYP2D6 revealed no poor metabolizers regarding CYP2C19 and only 2 (3.8%) poor metabolizers regarding CYP2D6. The presence of drugs metabolized by and/or inhibiting these enzymes in several of the cases suggests that such pharmacokinetic interactions are a more important (practical) problem than metabolic deficiency. Enantioselective analysis of citalopram and its metabolites can provide additional information when interpreting forensic toxicology results and might be a necessity in the future.
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| 10. |
- Kingbäck, Maria, et al.
(författare)
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Cytochrome P450-Dependent Disposition of the Enantiomers of Citalopram and Its Metabolites: In Vivo Studies in Sprague-Dawley and Dark Agouti Rats
- 2011
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Ingår i: Chirality. - : John Wiley and Sons, Ltd. - 0899-0042 .- 1520-636X. ; 23:2, s. 172-177
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Tidskriftsartikel (refereegranskat)abstract
- The female Sprague-Dawley (SD) and Dark Agouti (DA) rats are considered the animal counterparts of the human extensive and poor metabolizer cytochrome P450 (CYP) 2D6 phenotypes, respectively. The aim of this work was to study possible rat strain differences in the steady-state pharmacokinetics of the (+)-(S)- and (-)-(R)-enantiomers of citalopram and its demethylated metabolites. A chronic drug treatment regimen (15 mg/kg daily) was implemented for 13 days in separate groups of SD (n 5 9) and DA (n 5 9) rats by using osmotic pumps. The concentrations of citalopram and two major metabolites in serum and two brain regions were analyzed by an enantioselective high-performance liquid chromatography assay. Higher serum and brain levels of citalopram and demethylcitalopram, but lower levels of didemethylcitalopram, were observed in DA rats when compared with SD rats. The enantiomeric (S/R) concentrations ratios of citalopram were lower in the DA rats when compared with the SD rats (0.53 +/- 0.05 vs. 0.80 +/- 0.03, P andlt; 0.001), indicating a possibly decreased capacity in the metabolism of the (-)-(R)-enantiomer in the DA rats. This study shows that CYP2D deficiency results in steady-state pharmacokinetic differences of the enantiomers of citalopram and its metabolites.
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