Effects of apolipoprotein E deficiency on sphingosine-1-phosphate distribution in plasma and lipoproteins of mice / 中华心血管病杂志

Objective@#To investigate the effects of apolipoprotein E deficiency (Apo E-/-) on plasma and lipoprotein distribution of sphingosine-1-phosphate (S1P) in mice.@*Methods@#Five male or female Apo E-/- or wild type (WT) mice were fed with chow diet and sacrificed at 32-week-age and plasma was collected. The constituents of lipoprotein(very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL)) were separated by ultracentrifuge. The protein concentration of constituents was detected by BCA protein quantitative kit, and the S1P concentration in plasma and various lipoprotein constituents was detected by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Western blot was used to determine the plasma, liver, and kidney protein expression of apolipoprotein M(Apo M), which is considered as specific ligand of S1P.The S1P concentration in plasma and various constituents of lipoprotein in the Apo E-/- mice was compared to respective WT mice.@*Results@#(1)Plasma S1P content was significantly higher in the Apo E-/- groups than that of WT groups (male: (535.7±78.5)nmol/L vs. (263.3±22.0)nmol/L; female: (601.1±64.0)nmol/L vs. (279.0±33.9)nmol/L; all P<0.01). (2) Compared with WT mice, S1P content in non-HDL(LDL+ VLDL) was significantly higher in Apo E-/- mice (male: (504.9±52.8)nmol/L vs. (28.7±9.0)nmol/L; female: (427.7±27.4) vs. (27.8±4.7)nmol/L; after standardization of protein concentration, male: (385.0±41.2)pmol/mg protein vs. (71.4±6.6)pmol/mg protein; female: (330.2±22.0)pmol/mg protein vs. (67.2±12.1)pmol/mg protein; all P<0.01). (3) The expression of Apo M in plasma, liver and kidney was significantly higher in Apo E-/- groups than that of WT groups(all P<0.05).@*Conclusion@#The deficiency of Apo E could lead to upregulated S1P expression in the non-HDL, the underlying mechanism might be the increased transfer of HDL into the non-HDL by Apo M-S1P.

Comparative study of lipoprotein monosaccharide composition between diabetic patients and healthy participants / 中国病理生理杂志

AIM:To establish a liquid chromatography method for determining the monosaccharide composition of human lipoproteins, and to investigate the differences between diabetic patients and healthy participants.METHODS:Liquid chromatography with pre-column derivatization was used to determine the neutral and basic monosaccharides, and liquid chromatography tandem mass spectrometry was applied to quantify N-acetylneuraminic acid content.RESULTS:The contents of mannose, glucosamine, N-acetylglucosamine, glucose, galactose and N-acetylneuraminic acid in high-density lipoprotein from healthy participants and diabetic patients were (5.88 ±0.94),(16.49 ±4.11),(1.31 ±0.33), (0.87 ±0.16), (7.18 ±1.64), (2.14 ±0.12) mmol/(g protein) and (8.68 ±0.39), (24.73 ±5.50), (1.91 ±0.54), (1.23 ±0.35), (9.73 ±2.85), (3.53 ±0.27) mmol/(g protein), respectively.The contents of mannose, glu-cosamine,N-acetylglucosamine, glucose, galactose and N-acetylneuraminic acid in low-density lipoprotein from healthy par-ticipants and diabetic patients were ( 29.20 ±3.57 ) , ( 50.77 ±4.72 ) , ( 5.28 ±0.64 ) , ( 10.06 ±1.37 ) , ( 28.44 ± 3.96),(6.86 ±0.11) mmol/(g protein) and (30.08 ±3.78), (38.52 ±6.38), (3.79 ±0.78), (7.63 ±1.50), (20.05 ±2.63), (6.45 ±0.18) mmol/(g protein), respectively.The contents of mannose, glucosamine, glucose, ga-lactose and N-acetylneuraminic acid in very-low-density lipoprotein from healthy participants and diabetic patients were (91.21 ±4.12), (27.05 ±2.34), (4 230.95 ±15.83), (43.40 ±3.75), (2.95 ±0.24) mmol/(g protein) and (82.40 ±0.51), (30.16 ±0.32), (4 722.73 ±93.27), (34.05 ±2.81), (4.42 ±0.15) mmol/(g protein), respec-tively.CONCLUSION:Liquid chromatography with pre-column derivatization is suitable for the neutral and basic mono-saccharide analysis in human lipoproteins, and the glycosylation of lipoproteins in diabetic patients are significantly changed compared with the healthy controls.

Effects of phospholipid transfer protein overexpression on content of sphingosine-1-phosphate in mouse lipoprotein / 中国病理生理杂志

[ABSTRACT]AIM:Toinvestigatetheinteractionandthemechanismofsphingosine-1-phosphate(S1P)and phospholipid transfer protein (PLTP) in lipoprotein.METHODS:The S1P content in the plasma and lipoprotein from 10-week-old PLTP transgenic (PLTP-Tg) mice and wild-type (WT) mice (n=8 each) was assayed.The transport of S1P by PLTP was determined by S1P transfer assay.The content of specific S1P carrier, apolipoprotein M, was detected by West-ern blotting.RESULTS:Plasma S1P contents were decreased by 21.1%in PLTP-Tg mice compared with WT mice.S1P content in high-density lipoprotein ( HDL) fraction ( HDL-S1P) from PLTP-Tg mice was decreased by 35.1% compared with WT mice, whereas the S1P in low-density lipoprotein (LDL) fraction (LDL-S1P) was increased by 127.4%.The re-sults of S1P transfer assay indicated that PLTP facilitated S 1P transport from erythrocyte to recombinant liposome at 37℃in D-Hanks buffer solution .The plasma content of apolipoprotein M was not changed in PLTP-Tg mice compared with WT mice.CONCLUSION:PLTP is a key factor to maintain plasma HDL-S1P under physical condition .Overexpression of PLTP decreases the HDL-S1P but increases LDL-S1P.The mechanism might be related to the capability of PLTP on trans-ferring S1P from erythrocyte to lipoprotein.