Lactoferrin and its hydrolysate bind directly to the oleate-activated form of the lipolysis stimulated lipoprotein receptor.
The hepatic removal of triglyceride-rich chylomicrons during the postprandial phase represents an important step towards determining the bioavailability of dietary lipids amongst the peripheral tissues. Indeed, elevated postprandial lipemia is often associated with obesity and increased risk of coronary heart disease. The milk protein, lactoferrin, has been shown to inhibit hepatic chylomicron remnant removal by the liver, resulting in increased postprandial lipemia. Despite numerous studies on potential targets for lactoferrin, the molecular mechanisms underlying the effect of lactoferrin remain unclear. We recently demonstrated that the lipolysis stimulated lipoprotein receptor (LSR) contributes to the removal of triglyceride-rich lipoproteins during the postprandial phase. Here, we report that while lactoferrin does not have any significant effect on LSR protein levels in mouse Hepa1-6 cells, this protein colocalizes with LSR in cells but only in the presence of oleate, which is needed to obtain LSR in its active form as lipoprotein receptor. Ligand blotting using purified LSR revealed that lactoferrin binds directly to the receptor in the presence of oleate and prevents the binding of triglyceride-rich lipoproteins. Both C- and N-lobes of lactoferrin as well as a mixture of peptides derived from its hydrolysis retained the ability to bind LSR in its active form. We propose then that the elevated postprandial lipemia observed upon lactoferrin treatment in vivo is mediated in part by its direct interaction with free fatty acid activated LSR, thus preventing clearance of chylomicrons and their remnants through the LSR pathway.
Université de Lorraine, Unité de Recherche Animal et Fonctionnalités des Produits Animaux, Vandœuvre-lès-Nancy Cedex, France.
Nazir
N
Ahmad
Jean-Michel
JM
Girardet
Samina
S
Akbar
Marie-Claire
MC
Lanhers
Cédric
C
Paris
Frances T
FT
Yen
Catherine
C
Corbier
D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D045744:Cell Line, Tumor; D002914:Chylomicrons / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D006949:Hyperlipidemias / Q000378:metabolism; D007781:Lactoferrin / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D008079:Lipoproteins, VLDL / Q000378:metabolism; D008297:Male; D013058:Mass Spectrometry; D051379:Mice; D008810:Mice, Inbred C57BL; D019518:Postprandial Period / Q000187:drug effects; D011973:Receptors, LDL / Q000378:metabolism*; D014280:Triglycerides / Q000097:blood
D002914:Chylomicrons; D005227:Fatty Acids; D008079:Lipoproteins, VLDL; D011973:Receptors, LDL; D014280:Triglycerides; C085992:lipolysis-stimulated receptor; D007781:Lactoferrin