Cell-type-specific pathways of neurotensin endocytosis |
| |
Authors: | Cheryl Savdie Stephen S G Ferguson J– P Vincent Alain Beaudet Thomas Stroh |
| |
Institution: | (1) Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montréal, Québec, H3A 2B4, Canada;(2) Robarts Research Institute, Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada;(3) Institut de Pharmacologie Moléculaire et Cellulaire, CNRS, UMR 6097, Université de Nice Sophia-Antipolis, 06560 Valbonne, France |
| |
Abstract: | The neurotensin receptor subtype 1 (NTS1) is a G-protein-coupled receptor (GPCR) mediating a large number of central and peripheral
effects of neurotensin. Upon stimulation, NTS1 is rapidly internalized and targeted to lysosomes. This process depends on
the interaction of the phosphorylated receptor with β–arrestin. Little is known about other accessory endocytic proteins potentially
involved. Here, we investigated the involvement of dynamin, amphiphysin, and intersectin in the internalization of NTS1 receptor-ligand
complexes in transfected COS-7 and HEK 293 cells, by using the transferrin receptor as an internal control for the constitutive
endocytic pathway. We found that NTS1 endocytosis was not only arrestin–dependent, but also dynamin–dependent in both COS-7
and HEK 293 cells, whereas internalization of the transferrin receptor was independent of arrestin but required dynamin. Overexpression
of the SH3 domain of amphiphysin II had no effect on receptor internalization in either cell type. By contrast, overexpression
of full-length intersectin or of its SH3 domain (but not of its EH domain) inhibited NTS1 internalization in COS-7 but not
in HEK 293 cells. This difference between COS-7 and HEK 293 cells was not attributable to differences in endogenous intersectin
levels between the two cell lines. Indeed, the same constructs inhibited transferrin endocytosis equally well in COS-7 and
HEK 293 cells. However, immunogold electron microscopy revealed that internalized NTS1 receptors were associated with clathrin-coated
pits in COS-7 cells but with smooth vesicles in HEK 293 cells, suggesting that NTS1 internalization proceeds via different
endocytic pathways in these two cell types.
This work was supported by grants to A.B. from CIHR and FRSQ. |
| |
Keywords: | Neurotensin receptor subtype 1 (NTS1) Internalization Amphiphysin β – arrestin Dynamin Intersectin Immunoelectron microscopy COS-7 green monkey kidney cell HEK 293 human embryonic kidney cell |
本文献已被 PubMed SpringerLink 等数据库收录! |
|