EurekaMag.com logo
+ Site Statistics
References:
52,725,316
Abstracts:
28,411,598
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Polarized secretion of apoA-I and apoA-II by transfected MDCK cells


Journal of Lipid Research 36(3): 407-413
Polarized secretion of apoA-I and apoA-II by transfected MDCK cells
Apolipoproteins (apo) are secreted preferentially from the basolateral surface of hepatocytes and enterocytes. The polarized secretion of proteins is either mediated by a protein-dependent sorting signal or by a cell-dependent default pathway. In order to determine the mechanism for the polarized secretion of apolipoproteins, we examined the secretion of apoA-I and apoA-II in transfected Madin-Darby canine kidney (MDCK) cells. Transfected MDCK cells and Caco-2 cells were grown as a polarized monolayer on tissue culture inserts, which separate an upper apical compartment from the lower basolateral compartment, and the secretion of apoA-I and apoA-II into the apical and basolateral compartments was quantitated by immunoprecipitation. Caco-2 cells almost exclusively secreted apoA-I and apoA-II basolaterally, with an apical to basolateral ratio of 18:82 for apoA-I, and 11:89 for apoA-II. In contrast, transfected MDCK cells secreted significant amounts of apoA-I and apoA-II into both compartments, but with a bias toward apical secretion and an apical to basolateral ratio of 66:34 and 68:32, respectively. The polarized secretion of MDCK cells was not due to transcytosis, diffusion, or differential recovery. As assessed by density gradient ultracentrifugation, apoA-I and apoA-II secreted from either the apical or basolateral surface were relatively lipid-poor. Overall, these results suggest that the polarized secretion of apoA-I and apoA-II does not occur by a protein-dependent sorting signal, but by a cell-dependent default pathway that leads to preferential basolateral secretion by Caco-2 cells and both apical and basolateral secretion in MDCK cells, but with a bias toward apical secretion.


Accession: 009208274

PMID: 7775853



Related references

Targeted replacement of mouse apolipoprotein A-I with human ApoA-I or the mutant ApoA-IMilano. Evidence of APOA-IM impaired hepatic secretion. Journal of Biological Chemistry 278(7): 4740-4746, 2002

Carboxyl terminus of apolipoprotein A-I (ApoA-I) is necessary for the transport of lipid-free ApoA-I but not prelipidated ApoA-I particles through aortic endothelial cells. Journal of Biological Chemistry 286(10): 7744-7754, 2011

ApoA-I secretion from HepG2 cells: evidence for the secretion of both lipid-poor apoA-I and intracellularly assembled nascent HDL. Journal of Lipid Research 43(1): 36-44, 2002

ApoA-IV is secreted on discrete HDL particles by the rat hepatoma cell line McA-RH7777 transfected with ApoA-IV cDNA. Arteriosclerosis and Thrombosis 13(10): 1476-1486, 1993

Increased high density lipoprotein (HDL), defective hepatic catabolism of ApoA-I and ApoA-II, and decreased ApoA-I mRNA in ob. Journal of biological chemistry, 274(7): 4140-4146, 1999

Three genetic variants of human plasma apolipoprotein A-IV. apoA-IV-1(Thr347----Ser), apoA-IV-0(Lys167----Glu,Gln360----His), and apoA-IV-3(Glu165----Lys). Journal of Biological Chemistry 266(21): 13513-8, 1991

Subjects with ApoA-I(Lys107-->0) exhibit enhanced fractional catabolic rate of ApoA-I in Lp(AI) and ApoA-II in Lp(AI with AII). Arteriosclerosis, Thrombosis, and Vascular Biology 17(5): 873-880, 1997

Subjects with ApoA-I(Lys-107 fwdarw 0) exhibit enhanced fractional catabolic rate of ApoA-I in Lp(AI) and ApoA-II in Lp(AI with AII). Arteriosclerosis Thrombosis and Vascular Biology 17(5): 873-880, 1997

Different Functional and Structural Characteristics between ApoA-I and ApoA-4 in Lipid-Free and Reconstituted HDL State: ApoA-4 Showed Less Anti-Atherogenic Activity. Molecules and Cells 38(6): 573-579, 2016

Subjects with ApoA-I exhibit enhanced fractional catabolic rate of ApoA-I in Lp and ApoA-II in Lp. Arteriosclerosis Thrombosis & Vascular Biology 17(5): 873-880, 1997