Faculty Collaboration Database

Regulation of lysosomal and ubiquitin degradative pathways in differentiating human intestinal Caco-2 cells. Biochim Biophys Acta 1995 May 29;1267(1):15-24

Date

05/29/1995

Pubmed ID

7540043

DOI

10.1016/0167-4889(95)00027-p

Scopus ID

2-s2.0-0029018395 (requires institutional sign-in at Scopus site)   11 Citations

Abstract

The expression of various components of the lysosomal and ubiquitin-dependent degradative pathways was characterized in an in vitro model of differentiating enterocytes, the human colon adenocarcinoma Caco-2 cell line. The activities of the cell-associated lysosomal enzymes alpha-D-mannosidase, beta-hexosaminidase, beta-glucuronidase, and beta-galactosidase increased approximately 2- to 4-fold as differentiation proceeded. In contrast, the protein levels of the two mannose 6-phosphate receptors (MPRs), the insulin-like growth factor II/cation-independent MPR (IGF-II/CI-MPR) and the cation-dependent MPR (CD-MPR), did not change significantly during Caco-2 differentiation. In addition, quantitative Western blot analyses revealed that on a molar basis the CD-MPR is 3.5 times more abundant than the IGF-II/CI-MPR in Caco-2 cells. Since only limited secretion of lysosomal enzymes was observed throughout differentiation, the level of expression of the MPRs was sufficient to target the increased levels of lysosomal enzymes to the lysosome. Unlike the expression of lysosomal enzymes, Western blot analysis demonstrated an approximately 40% and approximately 30% decrease, respectively, in the steady-state levels of free and conjugated ubiquitin during Caco-2 differentiation. Taken together, these results show that the ubiquitin-dependent proteolytic pathway is regulated differently than the lysosomal degradative pathway during Caco-2 differentiation.

Author List

Zhang Y, Wick DA, Haas AL, Seetharam B, Dahms NM

Author

Nancy M. Dahms PhD Professor in the Biochemistry department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Base Sequence
Cations
Cell Differentiation
Cell Division
Cell Line
Gene Expression
Glucuronidase
Humans
Insulin-Like Growth Factor II
Intestinal Mucosa
Intestines
Lectins, C-Type
Lysosomes
Mannose-Binding Lectins
Mannosidases
Molecular Sequence Data
RNA
Receptors, Cell Surface
Ubiquitins
alpha-Mannosidase
beta-Galactosidase
beta-N-Acetylhexosaminidases