[3] Comparative analysis of mammalian plasma lipoproteins

Mj, Chapman

doi:10.1016/0076-6879(86)28063-5

Cited by 284 publications

(140 citation statements)

References 167 publications

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“…4,40 Sphingolipids, such as sphingomyelin, ceramide, and glucosylceramide, are integral components of lipoproteins. 8,41,42 In this study, we demonstrated that the VLDL, IDL, and LDL fractions contain markedly higher levels of ceramide, glucosylceramide, and sphingomyelin, whereas HDL contains higher amounts of ceramide and glucosylceramide. Recent studies by Merrill et al 8 have shown that de novo sphingolipid synthesis is not essential for lipoprotein secretion and that dietary changes that alter the rate of VLDL secretion do not alter the rate of hepatic sphingolipid synthesis.…”

Section: Discussionmentioning

confidence: 86%

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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Section: Discussionmentioning

confidence: 86%

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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“…The organic solvents were removed by tangential flow filtration against a 10-fold volume of lactose-sodium chloride solution. (Smith et al, 1985); the latter value was converted into holoprotein content by using the standard apoprotein percentages of each lipoprotein in rabbit serum (Chapman, 1986).…”

Section: Phthalocyaninementioning

confidence: 99%

CGP 55398, a liposomal Ge(IV) phthalocyanine bearing two axially ligated cholesterol moieties: a new potential agent for photodynamic therapy of tumours

Segalla

Milanesi²,

Jori³

et al. 1994

Br J Cancer

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Ge(IV) phthalocyanine (GePc) with two axially ligated cholesterol moieties was prepared by chemical synthesis and incorporated in a monomeric state into small unilamellar liposomes (CGP 55398). Upon photoexcitation with light wavelengths around its intense absorption peak at 680 nm, GePc shows an efficient photosensitising activity towards biological substrates through a mechanism which largely involves the intermediacy of singlet oxygen. GePc injected systemically into mice bearing an intramuscularly implanted MS-2 fibrosarcoma is quantitatively transferred to serum lipoproteins and localises in the tumour tissue with good efficiency: at 24 h post injection the GePc content in the tumour is 0.74 and 1.87 micrograms per g of tissue with a tumour/peritumoral ratio of 4.35 and 5.67 for injected doses of 0.76 and 1.52 mg kg-1 respectively. At this time the red-light irradiation of the GePc-loaded fibrosarcoma causes a fast and massive tumour necrosis involving both malignant cells and blood vessels. Images Figure 8 Figure 9 Figure 10 Figure 11 Figure 12

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“…The molecular weight (Mw) of apoA-I ranges from 25 to 29 kDa in vertebrates including fish [23][24][25][26][27][28]. Teleosts possess divergent isoforms within several apolipoprotein genes.…”

Section: Introductionmentioning

confidence: 99%

Isolation and characterization of some novel genes of the apolipoprotein A-I family in Japanese eel, Anguilla japonica

et al. 2011

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Apolipoproteins such as apolipoprotein (apo) A-I, apoA-IV, and apoE are lipid binding proteins synthesized mainly in the liver and the intestine and play an important role in the transfer of exogenous or endogenous lipids through the circulatory system. To investigate the mechanism of lipid transport in fish, we have isolated some novel genes of the apoA-I family, apoIA-I (apoA-I isoform) 1–11, from Japanese eel by PCR amplification. Some of the isolated genes of apoIA-I corresponded to 28kDa-1 cDNAs which had already been deposited into the database and encoded an apolipoprotein with molecular weight of 28 kDa in the LDL, whereas others seemed to be novel genes. The structural organization of all apoIA-Is consisted of four exons separated by three introns. ApoIA-I10 had a total length of 3232 bp, whereas other genes except for apoIA-I9 ranged from 1280 to 1441 bp. The sequences of apoIA-Is at the exon-intron junctions were mostly consistent with the consensus sequence (GT/AG) at exon-intron boundaries, whereas the sequences of 3′ splice acceptor in intron 1 of apoIA-I1-7 were (AC) but not (AG). The deduced amino acid sequences of all apoIA-Is contained a putative signal peptide and a propeptide of 17 and 5 amino acid residues, respectively. The mature proteins of apoIA-I1-3, 7, and 8 consisted of 237 amino acids, whereas those of apoIA-I4-6 consisted of 239 amino acids. The mature apoIA-I10 sequence showed 65% identity to amino acid sequence of apoIA-I11 which was associated with an apolipoprotein with molecular weight of 23 kDa in the VLDL. All these mature apoIA-I sequences satisfied the common structural features depicted for the exchangeable apolipoproteins such as apoA-I, apoA-IV, and apoE but apoIA-I11 lacked internal repeats 7, 8, and 9 when compared with other members of apoA-I family. Phylogenetic analysis showed that these novel apoIA-Is isolated from Japanese eel were much closer to apoA-I than apoA-IV and apoE, suggesting new members of the apoA-I family.

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[3] Comparative analysis of mammalian plasma lipoproteins

Cited by 284 publications

References 167 publications

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

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

CGP 55398, a liposomal Ge(IV) phthalocyanine bearing two axially ligated cholesterol moieties: a new potential agent for photodynamic therapy of tumours

Isolation and characterization of some novel genes of the apolipoprotein A-I family in Japanese eel, Anguilla japonica

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