| 1. |
- Asplund, Annika, 1979, et al.
(author)
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Hypoxia increases macrophage motility, possibly by decreasing the heparan sulfate proteoglycan biosynthesis.
- 2009
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In: Journal of leukocyte biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 86:2, s. 381-8
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Journal article (peer-reviewed)abstract
- Macrophages are recruited and retained in hypoxic sites in atherosclerotic lesions and tumors. Furthermore, macrophages are suggested to be a major source of HSPG synthesis in atherosclerotic lesions. HSPG are, among other things, known to regulate cell motility, cell adhesion, and receptor interaction. The aim of this study was to investigate the effect of hypoxia on HSPG expression and macrophage motility. We also explored the potential regulation of HSPG by the transcription factor HIF-1alpha. The nondirected cell motility was increased in HMDM after 24 h exposure to hypoxia (0.5% O(2)) compared with normal cell culture condition (21% O(2)). Enzymatic degradation of HS GAG further increased the motility of the HMDM in hypoxia, indicating a role of reduced cell-associated HSPG in the increased HMDM motility. HMDM exposed to 24 h of hypoxia had lower mRNA expressions of syndecan-1 and -4 compared with cells exposed to normal cell culture conditions. Protein levels of syndecan-1 were also decreased significantly in response to hypoxia, and cells subjected to hypoxia had lower mRNA expression for key enzymes involved in HS biosynthesis. In addition, hypoxia was found to reduce the relative content of HS GAG. Transfecting THP-1 cells with siHIF-1alpha indicated that this transcription factor was not involved in the hypoxia-induced modifications of HSPG expression. Given the documented multiple functions of HSPG in macrophage behavior, the hypoxia-induced modifications of HSPG may be of relevance for the development of atherosclerotic lesions and tumor progression.
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| 2. |
- Asplund, Annika, 1979, et al.
(author)
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Hypoxic regulation of secreted proteoglycans in macrophages.
- 2010
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In: Glycobiology. - : Oxford University Press (OUP). - 1460-2423 .- 0959-6658. ; 20:1, s. 33-40
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Journal article (peer-reviewed)abstract
- Macrophages are prominent in hypoxic areas of atherosclerotic lesions, and their secreted proteoglycans (PG), such as versican, can modulate the retention of lipoproteins and the activity of enzymes, cytokines, and growth factors involved in atherogenesis. In this study, we report the effects of hypoxia on PG secreted by human monocyte-derived macrophages (HMDM) and the potential regulation by the transcription factor hypoxia-inducible factor (HIF-1alpha and HIF-2alpha). We found that versican co-localized with HIF-1alpha in macrophage-rich areas in human advanced atherosclerotic lesions. Versican and perlecan mRNA expression increased after exposure to 0.5% O(2) (hypoxia) compared with 21% O(2) (control cells). Using precursors to GAG biosynthesis combined with immunoabsorption with a versican antibody an increased versican synthesis was detected at hypoxia. Furthermore, siRNA knockdown of HIF-1alpha and HIF-2alpha in THP-1 cells showed that the hypoxic induction of versican and perlecan mRNA expression involved HIF signaling. Versican expression was co-regulated by HIF-1alpha and HIF-2alpha but expression of perlecan was influenced only by HIF-1alpha and not by HIF-2alpha knockdown. The results show that oxygen concentration is an important modulator of PG expression in macrophages. This may be a novel component of the complex role of macrophages in atherosclerosis.
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| 3. |
- Asplund, Annika, 1979, et al.
(author)
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Macrophages exposed to hypoxia secrete proteoglycans for which LDL has higher affinity
- 2011
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In: ATHEROSCLEROSIS. - 0021-9150. ; 215:1, s. 77-81
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Journal article (peer-reviewed)abstract
- Macrophages are prominent in hypoxic areas of atherosclerotic lesions. Their secreted proteoglycans (PG) can modulate the retention of lipoproteins as well as the activity of enzymes, cytokines, and growth factors involved in atherogenesis. Versican appears to be one of the main extracellular matrix components binding LDL in the arterial intima. We have recently shown that hypoxia increases versican and perlecan expression in macrophages, and that this increase was regulated by the hypoxia inducible factor (HIF). Here we report effects of hypoxia on human monocyte-derived macrophage (HMDM) secreted glycosaminoglycans (GAG), and its interaction with LDL. After 24 h exposure to 0.5% O2 (hypoxia), metabolically labeled GAG of secreted PG had higher affinity for LDL compared to 21% O2 (control cells). GAG secreted by HMDM in hypoxia were found to be more sulfated and longer which might be responsible for the increased affinity of LDL for these GAG chains. These results indicate that hypoxia induced changes in macrophage GAG biosynthesis have important consequences for the interaction with LDL. If present in vivo, an augmented association of GAG with LDL might contribute to the development of atherosclerosis in hypoxic intima.
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| 4. |
- Davidsson, P., et al.
(author)
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A proteomic study of the apolipoproteins in LDL subclasses in patients with the metabolic syndrome and type 2 diabetes
- 2005
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In: J Lipid Res. - 0022-2275. ; 46:9, s. 1999-2006
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Journal article (peer-reviewed)abstract
- The exchangeable apolipoproteins present in small, dense LDL (sdLDL) and large, buoyant LDL subclasses were evaluated with a quantitative proteomic approach in patients with the metabolic syndrome and with type 2 diabetes, both with subclinical atherosclerosis and the B LDL phenotype. The analyses included surface-enhanced laser adsorption/ionization, time-of-flight mass spectrometry, and subsequent identification by mass spectrometry or immunoblotting and were carried out in LDL subclasses isolated by ultracentrifugation in deuterium oxide gradients with near physiological salt concentrations. The sdLDLs of both types of patients were enriched in apolipoprotein C-III (apoC-III) and were depleted of apoC-I, apoA-I, and apoE compared with matched healthy controls with the A phenotype. The LDL complexes formed in serum from patients with diabetes with the arterial proteoglycan (PG) versican were also enriched in apoC-III. In addition, there was a significant correlation between the apoC-III content in sdLDL in patients and the apparent affinity of their LDLs for arterial versican. The unique distribution of exchangeable apolipoproteins in the sdLDLs of the patients studied, especially high apoC-III, coupled with the augmented affinity with arterial PGs, may contribute to the strong association of the dyslipidemia of insulin resistance with increased risk for cardiovascular disease.
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| 5. |
- Davidsson, Pia, 1962, et al.
(author)
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Proteomics of Apolipoproteins and Associated Proteins From Plasma High-Density Lipoproteins.
- 2009
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In: Arteriosclerosis, thrombosis, and vascular biology. - 1524-4636.
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Journal article (peer-reviewed)abstract
- Proteomics studies have extended the list of identified apolipoproteins and associated proteins present in HDL and its subclasses. These proteins appear to cluster around specific functions related to lipid metabolism, inflammation, the immune system, hormone-binding, hemostasis, and antioxidant properties. Small studies suggest that there are substantial differences between the HDL proteome from cardiovascular disease patients and that from controls. Furthermore, dyslipidemia therapy shifts the HDL proteome from patients toward the profile observed in healthy controls. In addition, the proteome of HDL and LDL from patients with insulin resistance and peripheral atherosclerosis show significant differences with that of matched healthy controls. The proteome HDL and LDL density subclasses have apolipoproteins and associated proteins profiles that suggest subclass-specific functions. However, proteomics studies of lipoproteins are few and small and should be interpreted with caution. Nonetheless rapid technical progress in proteomic platforms suggest that soon analysis time will be reduced and precise measurement of identified proteins will be possible. This, combined with controlled purification steps of HDL and its subclasses should provide further information about proteins involved in the particles postulated spectrum of functions, including those believed to be atheroprotective.
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| 6. |
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| 7. |
- Rodríguez-Lee, Mariam, 1976, et al.
(author)
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Fatty acids cause alterations of human arterial smooth muscle cell proteoglycans that increase the affinity for low-density lipoprotein.
- 2006
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In: Arteriosclerosis, thrombosis, and vascular biology. - 1524-4636. ; 26:1, s. 130-5
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Journal article (peer-reviewed)abstract
- OBJECTIVE: The dyslipidemia of insulin resistance, with high levels of albumin-bound fatty acids, is a strong cardiovascular disease risk. Human arterial smooth muscle cell (hASMC) matrix proteoglycans (PGs) contribute to the retention of apoB lipoproteins in the intima, a possible key step in atherogenesis. We investigated the effects of high NEFA levels on the PGs secreted by hASMCs and whether these effects might alter the PG affinity for low-density lipoprotein. METHODS AND RESULTS: hASMC exposed for 72 hours to high concentrations (800 micromol/L) of linoleate (LO) or palmitate upregulated the core protein mRNAs of the major PGs, as measured by quantitative PCR. Insulin (1 nmol/L) and the PPARgamma agonist rosiglitazone (10 micromol/L) blocked these effects. In addition, high LO increased the mRNA levels of enzymes required for glycosaminoglycan (GAG) synthesis. Exposure to NEFA increased the chondroitin sulfate:heparan sulfate ratio and the negative charge of the PGs. Because of these changes, the GAGs secreted by LO-treated cells had a higher affinity for human low-density lipoprotein than GAGs from control cells. Insulin and rosiglitazone inhibited this increase in affinity. CONCLUSIONS: The response of hASMC to NEFA could induce extracellular matrix alterations favoring apoB lipoprotein deposition and atherogenesis.
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| 8. |
- Ståhlman, Marcus, 1975, et al.
(author)
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Proteomics and lipids of lipoproteins isolated at low salt concentrations in D2O/sucrose or in KBr.
- 2008
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In: Journal of lipid research. - 0022-2275. ; 49:2, s. 481-90
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Journal article (peer-reviewed)abstract
- There is much interest in the significance of apolipoproteins and proteins that are noncovalently associated with lipoproteins. It is possible that the high ionic strength used for isolation of lipoproteins with KBr and NaI could alter the pattern of associated exchangeable proteins. Here we describe lipoprotein classes fractionation from up to 0.5 ml of serum or plasma with buffers of physiological ionic strength and pH prepared with deuterium oxide (D(2)O) and sucrose. An advantage of the D(2)O/sucrose procedure was that the lipoproteins could be directly analyzed by the techniques described without need for desalting. We compared the isolated lipoproteins with those obtained using ultracentrifugation in KBr from the same plasma pool. Electrophoretic homogeneity of the lipoproteins was very similar using the two methods, as well as their lipid composition evaluated by HPLC. Two-dimensional electrophoresis and surface-enhanced laser adsorption/ionization time-of-flight mass spectrometry indicated that the patterns of exchangeable proteins of VLDL isolated using with the two procedures were very similar. However, significant differences were found in the profiles of LDL and HDL, indicating that the D(2)O/sucrose method allowed a more complete characterization of its exchangeable apolipoproteins and proteins.
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