Expression of insulin-like growth factor (IGF)-I receptors, IGF-II/cation-independent mannose 6-phosphate receptors (CI-MPRs), and cation-dependent MPRs in polarized human intestinal Caco-2 cells. Biochim Biophys Acta 1996 Feb 21;1279(1):84-92
Date
02/21/1996Pubmed ID
8624366DOI
10.1016/0005-2736(95)00234-0Scopus ID
2-s2.0-0030044859 (requires institutional sign-in at Scopus site) 15 CitationsAbstract
We have analyzed the surface distribution and functional expression of the insulin-like growth factor I (IGF-I) receptor and the IGF-II/cation-independent mannose 6-phosphate (IGF-II/CI-MPR) in the polarized human colon adenocarcinoma cell line, Caco 2. Domain-selective biotinylation of the apical and basolateral surfaces of Caco-2 cells grown on filter supports revealed a 3-4-fold enrichment of these receptors on basolateral membranes. In addition, the biotinylation studies revealed the presence of the cation-dependent MPR on both membrane surfaces, with a 3.4-fold enrichment on basolateral membranes. Binding of 125I-IGF-I at 4 degrees C confirmed similar higher levels of expression of the IGF-I receptor at the basolateral surface than at the apical surface. Cell surface-specific binding of the iodinated lysosomal enzyme beta-glucuronidase was detected at 4 degrees C on both plasma membrane domains. However, significant uptake of beta-glucuronidase at 37 degrees C was observed only from the basolateral surface. These results indicate that the MPRs and the IGF-I receptor are expressed in a polarized fashion in Caco-2 cells and that the IGF-II/CI-MPR present on apical membranes, unlike the IGF-II/CI-MPR expressed on the basolateral surface, is not functional in endocytosing lysosomal enzymes.
Author List
Dahms NM, Seetharam B, Wick DAAuthor
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 Polarity
Glucuronidase
Humans
Insulin-Like Growth Factor I
Intestines
Receptor, IGF Type 1
Receptor, IGF Type 2