scholarly journals Hepatic very-low-density lipoprotein and apolipoprotein B production are increased following in vivo induction of betaine–homocysteine S-methyltransferase

2006 ◽  
Vol 395 (2) ◽  
pp. 363-371 ◽  
Author(s):  
Janet D. Sparks ◽  
Heidi L. Collins ◽  
Doru V. Chirieac ◽  
Joanne Cianci ◽  
Jenny Jokinen ◽  
...  
Keyword(s):  
Apolipoprotein B ◽  
Serum Insulin ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Mrna Levels ◽  
Apob Mrna ◽  
Hepatic Triacylglycerol

We have previously reported a positive correlation between the expression of BHMT (betaine–homocysteine S-methyltransferase) and ApoB (apolipoprotein B) in rat hepatoma McA (McArdle RH-7777) cells [Sowden, Collins, Smith, Garrow, Sparks and Sparks (1999) Biochem. J. 341, 639–645]. To examine whether a similar relationship occurs in vivo, hepatic BHMT expression was induced by feeding rats a Met (L-methionine)-restricted betaine-containing diet, and parameters of ApoB metabolism were evaluated. There were no generalized metabolic abnormalities associated with Met restriction for 7 days, as evidenced by control levels of serum glucose, ketones, alanine aminotransferase and L-homocysteine levels. Betaine plus the Met restriction resulted in lower serum insulin and non-esterified fatty acid levels. Betaine plus Met restriction induced hepatic BHMT 4-fold and ApoB mRNA 3-fold compared with Met restriction alone. No changes in percentage of edited ApoB mRNA were observed on the test diets. An increase in liver ApoB mRNA correlated with an 82% and 46% increase in ApoB and triacylglycerol production respectively using in vivo Triton WR 1339. Increased secretion of VLDL (very-low-density lipoprotein) with Met restriction plus betaine was associated with a 45% reduction in liver triacylglycerol compared with control. Nuclear run-off assays established that transcription of both bhmt and apob genes was also increased in Met-restricted plus betaine diets. No change in ApoB mRNA stability was detected in BHMT-transfected McA cells. Hepatic ApoB and BHMT mRNA levels were also increased by 1.8- and 3-fold respectively by betaine supplementation of Met-replete diets. Since dietary betaine increased ApoB mRNA, VLDL ApoB and triacylglycerol production and decreased hepatic triacylglycerol, results suggest that induction of apob transcription may provide a potential mechanism for mobilizing hepatic triacylglycerol by increasing ApoB available for VLDL assembly and secretion.

scholarly journals Hepatic apolipoprotein E expression promotes very low density lipoprotein-apolipoprotein B production in vivo in mice

2000 ◽  
Vol 41 (10) ◽  
pp. 1673-1679 ◽  
Author(s):  
Cyrille Maugeais ◽  
Uwe J.F. Tietge ◽  
Kazuhisa Tsukamoto ◽  
Jane M. Glick ◽  
Daniel J. Rader
Keyword(s):  
Apolipoprotein E ◽  
Apolipoprotein B ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Hepatic Apolipoprotein

scholarly journals Interaction of 4-hydroxynonenal-modified low-density lipoproteins with the fibroblast apolipoprotein B/E receptor

1986 ◽  
Vol 234 (1) ◽  
pp. 245-248 ◽  
Author(s):  
W Jessup ◽  
G Jurgens ◽  
J Lang ◽  
H Esterbauer ◽  
R T Dean
Keyword(s):  
Apolipoprotein B ◽  
Negative Charge ◽  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Low Density ◽  
Lipid Peroxidation Product ◽  
Modified Low Density Lipoproteins ◽  
Peroxidation Product

The incorporation of the lipid peroxidation product 4-hydroxynonenal into low-density lipoprotein (LDL) increases the negative charge of the particle, and decreases its affinity for the fibroblast LDL receptor. It is suggested that this modification may occur in vivo, and might promote atherogenesis.

scholarly journals Rabbit and rat C-reactive proteins bind apolipoprotein B-containing lipoproteins.

1984 ◽  
Vol 159 (2) ◽  
pp. 604-616 ◽  
Author(s):  
I F Rowe ◽  
A K Soutar ◽  
I M Trayner ◽  
M L Baltz ◽  
F C de Beer ◽  
...  
Keyword(s):  
Acute Phase ◽  
Apolipoprotein B ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Plasma Lipoproteins ◽  
Free Form ◽  
Low Density ◽  
Serum Samples ◽  
Acute Phase Serum

Immobilized rabbit and rat C-reactive protein (CRP) were found to selectively bind apolipoprotein B (apoB)-containing lipoproteins (low density lipoprotein, LDL and very low density lipoprotein, VLDL) from whole serum in a manner similar to that previously reported with human CRP. In acute phase human serum the CRP is in a free form, not complexed with lipoprotein or any other macromolecular ligand, and in acute phase serum from most rabbits fed on a normal diet the rabbit CRP was also free. However, in acute phase serum or heparinized plasma from hypercholesterolemic rabbits part or all of the CRP was found by gel filtration and immunoelectrophoretic techniques to be complexed with beta-VLDL, an abnormal apoB-containing plasma lipoprotein present in these animals. The presence of extent in different serum samples of CRP complexed with lipoprotein correlated closely with the serum apoB concentration. The formation of complexes between native, unaggregated rabbit CRP in solution and apoB-containing lipoproteins was readily demonstrable experimentally both with the isolated proteins and in whole serum. In all cases these interactions were calcium-dependent and inhibitable by free phosphoryl choline. The present findings extend earlier work in man and the rabbit and indicate that among the C-reactive proteins from different species, which are structurally highly conserved, the capacity for selective binding to apoB-containing plasma lipoproteins is also a constant feature. These interactions may therefore be related to the in vivo function of CRP in all species and this function may in turn be relevant to pathological conditions, such as atherosclerosis, in which lipoproteins are important.

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