Induction of hepatic synthesis of serum amyloid A protein and actin.

Morrow, John F.; Stearman, Robert S.; Peltzman, Cynthia G.; Potter, David A.

doi:10.1073/pnas.78.8.4718

Cited by 163 publications

(106 citation statements)

References 37 publications

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“…Alternatively, lipid-free SAA may exert its effect through its ability to bind directly to SR-BI, thereby inhibiting HDL interaction with SR-BI. We have postulated that lipoprotein-free SAA exerts an inhibitory effect on SR-BI within the confines of the space of Disse, into which it is likely to be secreted in a lipid-free form (50).…”

Section: Discussionmentioning

confidence: 99%

Serum Amyloid A Is a Ligand for Scavenger Receptor Class B Type I and Inhibits High Density Lipoprotein Binding and Selective Lipid Uptake

Cai

Beer

et al. 2005

Journal of Biological Chemistry

159

141

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Serum amyloid A is an acute phase protein that is carried in the plasma largely as an apolipoprotein of high density lipoprotein (HDL). In this study we investigated whether SAA is a ligand for the HDL receptor, scavenger receptor class B type I (SR-BI), and how SAA may influence SR-BI-mediated HDL binding and selective cholesteryl ester uptake. Studies using Chinese hamster ovary cells expressing SR-BI showed that 125 Ilabeled SAA, both in lipid-free form and in reconstituted HDL particles, functions as a high affinity ligand for SR-BI. SAA also bound with high affinity to the hepatocyte cell line, HepG2. Alexa-labeled SAA was shown by fluorescence confocal microscopy to be internalized by cells in a SR-BI-dependent manner. To assess how SAA association with HDL influences HDL interaction with SR-BI, SAA-containing HDL was isolated from mice overexpressing SAA through adenoviral gene transfer. SAA presence on HDL had little effect on HDL binding to SR-BI but decreased (30 -50%) selective cholesteryl ester uptake. Lipid-free SAA, unlike lipid-free apoA-I, was an effective inhibitor of both SR-BI-dependent binding and selective cholesteryl ester uptake of HDL. We have concluded that SR-BI plays a key role in SAA metabolism through its ability to interact with and internalize SAA and, further, that SAA influences HDL cholesterol metabolism through its inhibitory effects on SR-BI-mediated selective lipid uptake.

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Section: Discussionmentioning

confidence: 99%

Serum Amyloid A Is a Ligand for Scavenger Receptor Class B Type I and Inhibits High Density Lipoprotein Binding and Selective Lipid Uptake

Cai

Beer

et al. 2005

Journal of Biological Chemistry

159

141

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“…We and others have found that LPS increases actin mRNA levels in liver by 2-fold to 5-fold in rodents. 4,18 TNF and IL-1 produce a 2-fold increase in actin mRNA levels. LPS also produced a 2-fold increase in hepatic mRNA levels for glyceraldehyde 3-phosphate dehydrogenase (G-3PD) and a 2.6-fold increase in cyclophilin mRNA.…”

Section: Isolation Of Rna and Northern Blottingmentioning

confidence: 99%

Endotoxin and Cytokines Increase Hepatic Sphingolipid Biosynthesis and Produce Lipoproteins Enriched in Ceramides and Sphingomyelin

Memon

Holleran

Moser

et al. 1998

ATVB

153

132

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Abstract-Alterations in triglyceride and cholesterol metabolism often accompany inflammatory diseases and infections.We studied the effects of endotoxin (lipopolysaccharide [LPS]) and cytokines on hepatic sphingolipid synthesis, activity of serine palmitoyltransferase (SPT), the first and rate-limiting enzyme in sphingolipid synthesis, and lipoprotein sphingolipid content in Syrian hamsters. Administration of LPS induced a 2-fold increase in hepatic SPT activity. The increase in activity first occurred at 16 hours, peaked at 24 hours, and was sustained for at least 48 hours. Low doses of LPS produced maximal increases in SPT activity, with half-maximal effect seen at Ϸ0.3 g LPS/100 g body weight.LPS increased hepatic SPT mRNA levels 2-fold, suggesting that the increase in SPT activity was due to an increase in SPT mRNA. LPS treatment also produced 75% and 2.5-fold increases in hepatic sphingomyelin and ceramide synthesis, respectively. Many of the metabolic effects of LPS are mediated by cytokines. Interleukin 1 (IL-1), but not tumor necrosis factor, increased both SPT activity and mRNA levels in the liver of intact animals, whereas both IL-1 and tumor necrosis factor increased SPT mRNA levels in HepG2 cells. IL-1 produced a 3-fold increase in SPT mRNA in HepG2 cells, and the half-maximal dose was 2 ng/mL. IL-1 also increased the secretion of sphingolipids into the medium. Increased hepatic fatty acid synthesis, as well as increased adipose tissue lipolysis, provides the fatty acid substrate for increased triglyceride production.3 High doses of LPS do not stimulate hepatic VLDL secretion 3 but inhibit the clearance of triglyceride-rich lipoproteins by decreasing lipoprotein lipase activity in heart, muscle, and adipose tissue and in postheparin plasma. In rodents, LPS treatment increases serum cholesterol levels; however, this effect is delayed in onset compared with the increase in serum triglyceride levels and is primarily accounted for by an increase in LDL cholesterol.4 LPS increases hepatic cholesterol synthesis and the activity of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate-limiting enzyme in cholesterol synthesis. 4Increased transcription of the HMG-CoA reductase gene leads to increased mRNA and protein levels, which account for the increase in hepatic HMG-CoA reductase activity. 5This effect of LPS on hepatic HMG-CoA reductase is specific, because mRNA levels of other important enzymes in cholesterol synthesis, such as HMG-CoA synthase, farnesyl pyrophosphate synthase, and squalene synthase, are not increased. 5,6 In addition, LPS decreases the activity and mRNA levels of cholesterol 7␣-hydroxylase, the rate-limiting enzyme in bile acid synthesis.7 A decrease in bile acid synthesis would increase the availability of cholesterol for lipoprotein production. Finally, LPS has minimal or no effect on LDL receptor protein or mRNA levels in the liver, the organ primarily responsible for LDL clearance. 4 These results suggest that the increased production of lipoproteins rather

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“…Soluble CD14 is primarily produced by hepatocytes in the liver, and its levels increase in inflammatory states, a characteristic of all acute phase proteins in the body, including serum amyloid A and C-reactive protein (53). Membrane-bound CD14 is primarily expressed by monocyte cell lineages (54,55).…”

mentioning

confidence: 99%

CD14 Protein Acts as an Adaptor Molecule for the Immune Recognition of Salmonella Curli Fibers

Rapsinski

Newman

Oppong

et al. 2013

Journal of Biological Chemistry

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Background: Curli fibers are recognized by the TLR2/TLR1 complex. Results: CD14 binds curli fibers and enhances TLR2/TLR1-dependent NF-B activation as well as cytokine and nitrite production. Conclusion: CD14 is an adaptor protein for the TLR2/TLR1 complex binding the fibrillar structure of curli fibers. Significance: Understanding the immune receptor complexes that recognize amyloids will have implications for amyloidassociated diseases.

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Induction of hepatic synthesis of serum amyloid A protein and actin.

Cited by 163 publications

References 37 publications

Serum Amyloid A Is a Ligand for Scavenger Receptor Class B Type I and Inhibits High Density Lipoprotein Binding and Selective Lipid Uptake

Serum Amyloid A Is a Ligand for Scavenger Receptor Class B Type I and Inhibits High Density Lipoprotein Binding and Selective Lipid Uptake

Endotoxin and Cytokines Increase Hepatic Sphingolipid Biosynthesis and Produce Lipoproteins Enriched in Ceramides and Sphingomyelin

CD14 Protein Acts as an Adaptor Molecule for the Immune Recognition of Salmonella Curli Fibers

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