Lipoprotein and apolipoprotein secretion by a newborn piglet
intestinal cell line (ipec-1).
Gonzalez-Vallina, Ruben, Heng Wang, Reggie Zhan, Helen M.
Berschneider, Robert M. Lee, Nicholas O. Davidson, and Dennis D.
Black.
Department of Pediatrics, Arkansas Children's Hospital, University
of Arkansas for Medical Sciences, Little Rock, AR 72202; Departments
of Pediatrics and Medicine, University of Chicago Pritzker School of
Medicine, Chicago, IL 60637; and College of Veterinary Medicine,
North Carolina State University, Raleigh, NC 27606
APStracts 3:0036G, 1996.
The aim of these studies was to characterize the synthesis and
secretion of lipoproteins and apolipoproteins B and 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 A-I secreted
increased with oleic acid incubation. However, cellular apo B and A-I
content did not change. Whereas undifferentiated cells synthesized
and secreted only apo B-100, both apo B-100 and B-48 were produced by
differentiated cells. The ratio of radiolabelled apo B-48 to B-100 in
both basolateral medium and cell homogenate increased with oleic acid
treatment after 24 hr steady-state labelling. However, apo B mRNA
editing was unchanged, indicating post-translational regulation of
this ratio. Pulse-chase radiolabelling demonstrated no major changes
in cellular or basolateral medium apolipoprotein labelling kinetics
with oleic acid or dexamethasone incubation. The dissociation of apo
B and A-I mass secretion from the secretion of radiolabelled B and A
-I in response to oleic acid absorption suggests the presence of an
intracellular pool of apolipoprotein with a slow turnover which is
mobilized for secretion in response to fatty acid uptake.
Received 30 August 1995; accepted in final form 19 January 1996.
APS Manuscript Number G381-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96