MECHANISMS OF LIPID TRANSCYTOSIS THROUGH SMALL INTESTINE ENTEROCYTES

Abstract

The article presents a review of studies of lipid transcytosis in enterocyte of intestinal villi. The known data and hypotheses of lipid transport are analyzed: through the plasmolemma of the enterocyte, from the endasmic reticulum through the Golgi complex, through the Golgi complex, from the zone of intercellular contacts into the intestinal villus lamina propria. The data on lipid uptake by the apical part of plasmolemma without endocytosis are presented. The main protein mechanisms that ensure the assembly of pre chylomicron in the endoplasmic reticulum and its further movement into the Golgi complex are described. The role of the COPII coating and its subunits in the transport of pre chylomicron from the endpasmic reticulum to the Golgi complex is discussed. Convincing evidence is provided for the need for a COPII coating in transporting lipids through an enterocyte, while COPII-derived vesicles are not formed. The models of the existing chylomicron transport through the Golgi complex and the participation of the main protein machines in that process are analyzed. The evidence of the insolvency of the «vesicular» and the model of «maturation and progression of tanks is presented. A hypothesis has been put forward on the most probable model of chylomicron transport through the Golgi complex based on the “incomplete fusion” of membranes - the “kiss and run” model. The role of enterocyte cytoskeleton in lipid transcytosis was shown. The data of studies of lipid transport under high lipid loading conditions are presented, which demonstrate the accumulation of lipid droplets in the cytosol of the apical part of the cell, in the immediate vicinity of the endasmic reticulum. The data presented substantially complement our understanding of lipid transcytosis through enterocyte of intestinal villi, however, the hypotheses put forward by the authors require further study and search for morphological evidence.