Cholesterol depletion of enterocytes - Effect on the Golgi complex and apical membrane trafficking

Citation
Gh. Hansen et al., Cholesterol depletion of enterocytes - Effect on the Golgi complex and apical membrane trafficking, J BIOL CHEM, 275(7), 2000, pp. 5136-5142
Citations number
51
Categorie Soggetti
Biochemistry & Biophysics
Journal title
JOURNAL OF BIOLOGICAL CHEMISTRY
ISSN journal
00219258 → ACNP
Volume
275
Issue
7
Year of publication
2000
Pages
5136 - 5142
Database
ISI
SICI code
0021-9258(20000218)275:7<5136:CDOE-E>2.0.ZU;2-T
Abstract
Intestinal brush border enzymes, including aminopeptidase N and sucrase-iso maltase, are associated with "rafts" (membrane microdomains rich in cholest erol and sphingoglycolipids), To assess the functional role of rafts in the present work, we studied the effect of cholesterol depletion on apical mem brane trafficking in enterocytes, Cultured mucosal explants of pig small in testine were treated for 2 h with the cholesterol sequestering agent methyl -beta-cyclodextrin and lovastatin, an inhibitor of hydroxymethylglutaryl-co enzyme A reductase, The treatment reduced the cholesterol content >50%. Mor phologically, the Gels complex/trans-Golgi network was partially transforme d into numerous 100-200 nm vesicles. By immunogold electron microscopy, ami nopeptidase N was localized in these Golgi-derived vesicles as well as at t he basolateral cell surface, indicating a partial missorting. Biochemically , the rates of the Golgi-associated complex glycosylation and association w ith rafts of newly synthesized aminopeptidase N were reduced, and less of t he enzyme had reached the brush border membrane after 2 h of labeling. In c ontrast, the basolateral Na+/K+-ATPase was neither missorted nor raft-assoc iated. Our results implicate the Golgi complex/trans-Golgi network in raft formation and suggest a close relationship between this event and apical me mbrane trafficking.