Regulated vectorial secretion of cholesteryl ester transfer protein (LTP-I) by the CaCo-2 model of human enterocyte epithelium.
We have investigated the human CaCo-2 enterocyte model for secretion of the plasma cholesteryl ester transfer protein, LTP-I. CaCo-2 cells secrete a cholesteryl ester transfer protein which possesses molecular identity with plasma LTP-I, demonstrated by anti-LTP-I immunoblot analysis and immunoinhibition of all cell-secreted cholesteryl ester transfer activity. When CaCo-2 are cultured on permeable membranes, cholesteryl ester transfer activity is detected only in the lower culture compartment. Thus, CaCo-2 vectorially sort and secrete LTP-I, as well as the intestinal apolipoproteins, from the basolateral cellular domain. Over a 24-h period, CaCo-2 secrete cholesteryl ester transfer activity in a time-dependent manner, at approximately twice the rate of HepG2. Furthermore, CaCo-2 enterocytes, but not HepG2 hepatocytes, regulate LTP-I secretion in response to fatty acid concentration in the culture medium. Based on these observations, we speculate that the intestine may be the principal regulated source of human plasma LTP-I.
Faust
R A
RA
Department of Medicine, University of Washington School of Medicine, Seattle 98104.
Albers
J J
JJ
D001053:Apolipoproteins / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D053480:Cholesterol Ester Transfer Proteins; D004848:Epithelium / Q000378:metabolism; D006023:Glycoproteins; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007700:Kinetics; D008113:Liver Neoplasms / Q000378:metabolism; D008954:Models, Biological; D019301:Oleic Acid; D009829:Oleic Acids / Q000378:metabolism
D001053:Apolipoproteins; C506642:CETP protein, human; D002352:Carrier Proteins; D053480:Cholesterol Ester Transfer Proteins; D006023:Glycoproteins; D009829:Oleic Acids; D019301:Oleic Acid