Hepatitis C virus core protein inhibits microsomal triglyceride transfer protein activity and very low density lipoprotein secretion: a model of viral‐related steatosis

2002 ◽  
Vol 16 (2) ◽  
pp. 185-194 ◽  
Author(s):  
Gabriel Perlemuter ◽  
Abdelmajid Sabile ◽  
Philippe Letteron ◽  
Giovanna Vona ◽  
André Topilco ◽  
...  
Keyword(s):  
Core Protein ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Microsomal Triglyceride Transfer Protein ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Protein Activity ◽  
Transfer Protein ◽  
Virus Core ◽  
Lipoprotein Secretion

scholarly journals Microsomal triglyceride transfer protein activity remains unchanged in rat livers under conditions of altered very-low-density lipoprotein secretion

1995 ◽  
Vol 310 (1) ◽  
pp. 11-14 ◽  
Author(s):  
D J Brett ◽  
R J Pease ◽  
J Scott ◽  
G F Gibbons
Keyword(s):  
Cultured Cells ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Microsomal Triglyceride Transfer Protein ◽  
Autosomal Recessive Disorder ◽  
Diabetic Rat ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Protein Activity ◽  
Transfer Protein

Microsomal triglyceride transfer protein (MTP) is a heterodimeric protein consisting of a unique 97 kDa subunit and protein disulphide isomerase, that mediates the transfer of lipid between membranes and nascent lipoproteins. Mutations in the gene encoding the 97 kDa subunit of the protein cause the rare autosomal recessive disorder abetalipoproteinaemia. Recent findings in cultured cells indicate that the 5′ promoter region contains an insulin-responsive element, suggesting that the gene is responsive to insulin regulation. In this study we examined two cases where very-low-density lipoprotein (VLDL) secretion is markedly reduced: the streptozotocin-diabetic rat and 10-day-old suckling rats. In both cases MTP activity was unaltered compared with that in control animals. Equal levels of MTP were also apparent in the livers of all groups of animals, as measured by immunoblotting with an anti-MTP antiserum. These findings indicate that factors other than MTP activity are responsible for the reduction in hepatic VLDL triglyceride secretion observed in the suckling and diabetic animals.

scholarly journals miR-130b is a potent stimulator of hepatic very-low-density lipoprotein assembly and secretion via marked induction of microsomal triglyceride transfer protein

2020 ◽  
Vol 318 (2) ◽  
pp. E262-E275 ◽  
Author(s):  
Jing Zhang ◽  
Ferdous Rastgar Jazii ◽  
Mahdi Montazer Haghighi ◽  
Danielle Alvares ◽  
Lipei Liu ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Hepg2 Cells ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Microsomal Triglyceride Transfer Protein ◽  
Luciferase Reporter ◽  
Very Low Density Lipoprotein ◽  
Low Density ◽  
Transfer Protein ◽  
Stimulation Of

miR-130b is a microRNA whose expression is particularly elevated within adipose tissue and in the circulation in diabetic states. Hepatic miR-130b expression has been linked to hepatocellular carcinoma and changes in lipid metabolism. Here, we investigated the role of miR-130b in hepatic lipid homeostasis and lipoprotein export. We observed that overexpression of miR-130b-3p or -5p in HepG2 cells markedly enhanced the secretion of very-low-density lipoprotein (VLDL) particles, enhanced the secretion of [3H]glycerol metabolically labeled triglyceride (TG), and significantly increased the number or the average size of lipid droplets (LDs), respectively. Overexpression of miR-130b also altered the expression of key genes involved in lipid metabolism and in particular markedly increased both mRNA and protein expression levels of microsomal triglyceride transfer protein (MTP). Conversely, the miR-130b inhibitor decreased mRNA levels of MTP and fatty acid synthase ( FAS) in HepG2 cells. However, dual-luciferase reporter assays indicated that MTP is not a direct target of miR-130b-3p. miR-130b overexpression did not alter de novo synthesized TG or the stability and secretion of apolipoprotein B 100. Interestingly, knockdown of phosphatase and tensin homolog ( PTEN) blocked the upregulation of MTP mRNA induced by miR-130b. Finally, miR-130b-induced stimulation of VLDL secretion was also observed in a second hepatocyte cell culture model, immortalized human hepatocytes, confirming the effects observed in HepG2 cells. Overall, these data suggest a potential role for miR-130b in promoting hepatic VLDL assembly and secretion mediated by marked stimulation of MTP expression and TG mobilization. Thus miR-130b overexpression corrects the defect in VLDL production in HepG2 cells.

Sign in / Sign up

Export Citation Format

Share Document