C. Sharma et al., FIBRONECTIN SYNTHESIS BY AORTA EXPLANTS FROM RABBITS FED HIGH CHOLESTEROL DIETS, Proceedings of the Society for Experimental Biology and Medicine, 204(3), 1993, pp. 312-317
Fibronectin synthesis was studied in aorta explants in culture from ra
bbits fed a high fat-high cholesterol diet. [H-3]Mannose and [C-14]leu
cine were used to label oligosaccharide side chains and the protein co
re, respectively. The synthesis was followed by monitoring immunopreci
pitable fibronectin from the culture medium using polyclonal goat anti
-rabbit fibronectin antibody. synthesis of fibronectin increased by [C
-14]leucine (81%) and [H-3]mannose (29%) incorporation over controls.
On gel filtration, fibronectin synthesized by controls and cholesterol
-fed rabbit resolved into four fractions. Pulse-chase experiment with
[H-3]glucosamine or [H-3]leucine showed that fibronectin secreted by t
he aorta explants from rabbits fed high fat-high cholesterol diets inc
orporated an increased amount of radioactivity. Pulsing with [H-3]mann
ose showed decreased incorporation of the label. During the chase peri
od, the rate of secretion of fibronectin into the media by the hyperch
olesterolemic rabbit aorta explants was increased. The fibronectin tha
t bound to the gelatin or heparin columns from cholesterol-fed rabbit
aorta media had lower levels of [H-3]mannose incorporated into the gly
coprotein than the control. These results indicate that there is an al
teration in carbohydrate composition of the fibronectin synthesized by
the aorta explants from rabbits fed a high cholesterol diet. High fat
-cholesterol intake could play a causative role in matrix dysfunction
during atherogenesis by altering glycoprotein synthesis.