Novel Mechanism for Regulation of Epidermal Growth Factor Receptor Endocytosis Revealed by Protein Kinase A Inhibition
Open Access
- 1 May 2002
- journal article
- Published by American Society for Cell Biology (ASCB) in Molecular Biology of the Cell
- Vol. 13 (5), 1677-1693
- https://doi.org/10.1091/mbc.01-08-0403
Abstract
Current models put forward that the epidermal growth factor receptor (EGFR) is efficiently internalized via clathrin-coated pits only in response to ligand-induced activation of its intrinsic tyrosine kinase and is subsequently directed into a lysosomal-proteasomal degradation pathway by mechanisms that include receptor tyrosine phosphorylation and ubiquitylation. Herein, we report a novel mechanism of EGFR internalization that does not require ligand binding, receptor kinase activity, or ubiquitylation and does not direct the receptor into a degradative pathway. Inhibition of basal protein kinase A (PKA) activity by H89 and the cell-permeable substrate peptide Myr-PKI induced internalization of 40–60% unoccupied, inactive EGFR, and its accumulation into early endosomes without affecting endocytosis of transferrin and μ-opioid receptors. This effect was abrogated by interfering with clathrin function. Thus, the predominant distribution of inactive EGFR at the plasma membrane is not simply by default but involves a PKA-dependent restrictive condition resulting in receptor avoidance of endocytosis until it is stimulated by ligand. Furthermore, PKA inhibition may contribute to ligand-induced EGFR endocytosis because epidermal growth factor inhibited 26% of PKA basal activity. On the other hand, H89 did not alter ligand-induced internalization of EGFR but doubled its half-time of down-regulation by retarding its segregation into degradative compartments, seemingly due to a delay in the receptor tyrosine phosphorylation and ubiquitylation. Our results reveal that PKA basal activity controls EGFR function at two levels: 1) residence time of inactive EGFR at the cell surface by a process of “endocytic evasion,” modulating the accessibility of receptors to stimuli; and 2) sorting events leading to the down-regulation pathway of ligand-activated EGFR, determining the length of its intracellular signaling. They add a new dimension to the fine-tuning of EGFR function in response to cellular demands and cross talk with other signaling receptors.Keywords
This publication has 74 references indexed in Scilit:
- Kinase Signaling Initiates Coat Complex II (COPII) Recruitment and Export from the Mammalian Endoplasmic ReticulumJournal of Biological Chemistry, 2000
- Polyubiquitination of the Epidermal Growth Factor Receptor Occurs at the Plasma Membrane upon Ligand-induced ActivationPublished by Elsevier BV ,2000
- Gβγ-Mediated Regulation of Golgi Organization Is through the Direct Activation of Protein Kinase DCell, 1999
- Pseudosubstrate Inhibition of Cyclic AMP-Dependent Protein Kinase in Intact Pancreatic Islets: Effects on Cyclic AMP-Dependent and Glucose-Dependent Insulin SecretionBiochemical and Biophysical Research Communications, 1997
- A Regulatory Role for cAMP-dependent Protein Kinase in Protein Traffic along the Exocytic RoutePublished by Elsevier BV ,1996
- Epidermal Growth Factor Receptor Interaction with Clathrin Adaptors Is Mediated by the Tyr974-containing Internalization MotifJournal of Biological Chemistry, 1996
- Localization of Epidermal Growth Factor-stimulated Ras/Raf-1 Interaction to Caveolae MembranePublished by Elsevier BV ,1996
- A detergent-free method for purifying caveolae membrane from tissue culture cells.Proceedings of the National Academy of Sciences of the United States of America, 1995
- Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications.Proceedings of the National Academy of Sciences, 1979
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970