Guar gum consumption increases hepatic nuclear SREBP2 and LDL receptor expression in pigs fed an atherogenic diet.
To gain insight into the regulation of hepatic sterol-responsive genes that are thought to mediate the hypocholesterolemic effects of guar gum (GG) consumption, the mRNA and protein expression of sterol regulatory element binding protein 2 (SREBP2), LDL receptor (LDLr), and scavenger receptor class B, type 1 (SR-B1) were examined in pigs consuming an atherogenic control diet or the control diet supplemented with 10% GG. Compared with the control group, GG consumption reduced (P < 0.05) plasma total cholesterol and LDL cholesterol concentrations by 27 and 37%, respectively. Furthermore, hepatic free cholesterol concentration was lower (P < 0.05) in the GG-fed pigs in comparison with the control group. GG consumption increased hepatic LDLr mRNA (1.5-fold of the control, P = 0.09) and protein (2-fold of the control, P < 0.05) expression in comparison with the control group. However, GG consumption reduced hepatic SR-B1 mRNA to 36% of the control (P < 0.05) expression but did not affect (P = 0.19) SR-B1 protein abundance in comparison with the control group. Although SREBP2 mRNA expression was similar (P = 0.89) in the 2 groups, GG consumption increased (P < 0.05) the expression of the cytoplasmic precursor (3-fold of the control) and nuclear active forms (1.5-fold of the control) of SREBP2. We conclude that the hypocholesterolemic effects of GG consumption are related to a reduction in hepatic free cholesterol concentration and associated increases in nuclear active SREBP2 expression and hepatic LDLr abundance.
Rideout
Todd C
TC
Centre for Nutrition Modelling, Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1. trideout@uoguelph.ca
Yuan
Zongfei
Z
Bakovic
Marica
M
Liu
Qiang
Q
Li
Ren-Ke
RK
Mine
Yoshinori
Y
Fan
Ming Z
MZ
D000818:Animals; D000924:Anticholesteremic Agents / Q000008:administration & dosage; D050197:Atherosclerosis / Q000178:diet therapy / Q000235:genetics / Q000378:metabolism / Q000517:prevention & control; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004036:Diet, Atherogenic; D004043:Dietary Fiber / Q000008:administration & dosage; D005685:Galactans / Q000008:administration & dosage; D008099:Liver / Q000378:metabolism*; D008351:Mannans / Q000008:administration & dosage; D053149:Plant Gums / Q000008:administration & dosage; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011973:Receptors, LDL / Q000235:genetics* / Q000378:metabolism*; D051782:Sterol Regulatory Element Binding Protein 2 / Q000235:genetics* / Q000378:metabolism*; D034421:Sus scrofa
D000924:Anticholesteremic Agents; D017931:DNA Primers; D004043:Dietary Fiber; D005685:Galactans; D008351:Mannans; D053149:Plant Gums; D012333:RNA, Messenger; D011973:Receptors, LDL; D051782:Sterol Regulatory Element Binding Protein 2; C007894:guar gum