Biosynthesis and secretion of the mannose 6-phosphate receptor and its ligands in polarized Caco-2 cells. Am J Physiol 1999 Sep;277(3):G506-14
Date
09/14/1999Pubmed ID
10484374DOI
10.1152/ajpgi.1999.277.3.G506Scopus ID
2-s2.0-0032861253 (requires institutional sign-in at Scopus site) 9 CitationsAbstract
We have analyzed the transport of newly synthesized mannose 6-phosphate (Man-6-P)-bearing proteins (i.e., lysosomal enzymes) in the polarized human colon adenocarcinoma cell line, Caco-2, by subjecting filter-grown cells to a pulse-chase labeling protocol using [(35)S]methionine, and the resulting cell lysate, apical medium, and basolateral medium were immunoprecipitated with insulin-like growth factor II/Man-6-P receptor (IGF-II/MPR)-specific antisera. The results showed that the majority of secreted lysosomal enzymes accumulated in the apical medium at >2 h of chase and that this polarized distribution was facilitated by the IGF-II/MPR selectively endocytosing lysosomal enzymes from the basolateral surface. Treatment with various agents known to affect vesicular transport events demonstrated that incubations at 16 degrees C or incubations with brefeldin A inhibited the secretion of lysosomal enzymes from both the apical and basolateral surface, whereas treatment with nocodazole selectively blocked apical secretion. In contrast, incubation with NH4Cl or nocodazole had a stimulatory effect on basolateral secretion. Taken together, these results demonstrate that the sorting of Man-6-P-containing proteins into the apical and basolateral secretory pathways is regulated by distinct components of the intracellular trafficking machinery.
Author List
Wick DA, Seetharam B, Dahms NMAuthor
Nancy M. Dahms PhD Professor in the Biochemistry department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Caco-2 CellsCell Membrane
Cell Polarity
Humans
Insulin-Like Growth Factor II
Intestinal Mucosa
Intracellular Membranes
Ligands
Receptor, IGF Type 2
