Lipoprotein and apolipoprotein secretion by a newborn piglet intestinal cell line (IPEC-1).
The aim of these studies was to characterize the synthesis and secretion of lipoproteins and apolipoprotein B (apo B) and apo A-I by a newborn swine intestinal epithelial cell line (IPEC-1). Differentiated cells exhibited enterocytic features, including microvilli. [3H] oleic acid was taken up and incorporated into cellular lipids and secreted into the basolateral medium in lipoproteins. Total apo B and apo A-I secreted increased with oleic acid incubation. However, cellular apo B and apo A-I content did not change. Whereas undifferentiated cells synthesized and secreted only apo B-100, both apo B-100 and apo B-48 were produced by differentiated cells. The ratio of radiolabeled apo B-48 to apo B-100 in both basolateral medium and cell homogenate increased with oleic acid treatment after 24-h steady-state labeling. However, apo B mRNA editing was unchanged, indicating posttranslational regulation of this ratio. Pulse-chase radiolabeling demonstrated no major changes in cellular or basolateral medium apolipoprotein labeling kinetics with oleic acid or dexamethasone incubation. The dissociation of apo B and apo A-I mass secretion from the secretion of radiolabeled apo B and apo A-I in response to oleic acid absorption suggests the presence of an intracellular pool of apolipoprotein with a slow turnover that is mobilized for secretion in response to fatty acid uptake.
Gonzalez-Vallina
R
R
Department of Pediatrics, Arkansas Children's Hospital, University of Arkansas for Medical Sciences, Little Rock 72202, USA.
Wang
H
H
Zhan
R
R
Berschneider
H M
HM
Lee
R M
RM
Davidson
N O
NO
Black
D D
DD
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D001053:Apolipoproteins / Q000378:metabolism*; D001055:Apolipoproteins B / Q000235:genetics; D001483:Base Sequence; D002454:Cell Differentiation; D002460:Cell Line; D004951:Esterification; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D008074:Lipoproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D019301:Oleic Acid / Q000378:metabolism; D015345:Oligonucleotide Probes / Q000235:genetics; D017393:RNA Editing; D013552:Swine
D001053:Apolipoproteins; D001055:Apolipoproteins B; D008074:Lipoproteins; D015345:Oligonucleotide Probes; D019301:Oleic Acid