The GTPase ARFRP1 controls the lipidation of chylomicrons in the Golgi of the intestinal epithelium

Hum Mol Genet. 2012 Jul 15;21(14):3128-42. doi: 10.1093/hmg/dds140. Epub 2012 Apr 14.

Abstract

The uptake and processing of dietary lipids by the small intestine is a multistep process that involves several steps including vesicular and protein transport. The GTPase ADP-ribosylation factor-related protein 1 (ARFRP1) controls the ARF-like 1 (ARL1)-mediated Golgi recruitment of GRIP domain proteins which in turn bind several Rab-GTPases. Here, we describe the essential role of ARFRP1 and its interaction with Rab2 in the assembly and lipidation of chylomicrons in the intestinal epithelium. Mice lacking Arfrp1 specifically in the intestine (Arfrp1(vil-/-)) exhibit an early post-natal growth retardation with reduced plasma triacylglycerol and free fatty acid concentrations. Arfrp1(vil-/-) enterocytes as well as Arfrp1 mRNA depleted Caco-2 cells absorbed fatty acids normally but secreted chylomicrons with a markedly reduced triacylglycerol content. In addition, the release of apolipoprotein A-I (ApoA-I) was dramatically decreased, and ApoA-I accumulated in the Arfrp1(vil-/-) epithelium, where it predominantly co-localized with Rab2. The release of chylomicrons from Caco-2 was markedly reduced after the suppression of Rab2, ARL1 and Golgin-245. Thus, the GTPase ARFRP1 and its downstream proteins are required for the lipidation of chylo-microns and the assembly of ApoA-I to these particles in the Golgi of intestinal epithelial cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP-Ribosylation Factors / genetics
  • ADP-Ribosylation Factors / metabolism*
  • Animals
  • Apolipoprotein A-I / metabolism
  • Chylomicrons / metabolism*
  • GTP Phosphohydrolases / genetics
  • GTP Phosphohydrolases / metabolism*
  • Golgi Apparatus / enzymology*
  • Golgi Apparatus / metabolism
  • Humans
  • Intestinal Mucosa / enzymology*
  • Intestinal Mucosa / metabolism
  • Lipid Metabolism
  • Mice
  • Mice, Knockout
  • Protein Binding
  • Protein Transport
  • rab2 GTP-Binding Protein / genetics
  • rab2 GTP-Binding Protein / metabolism

Substances

  • Apolipoprotein A-I
  • Chylomicrons
  • GTP Phosphohydrolases
  • ADP-Ribosylation Factors
  • ARFRP1 protein, human
  • Arfrp1 protein, mouse
  • rab2 GTP-Binding Protein