Related Experiment Videos
Compartmentalization of the mitogen-activated protein kinase (MAPK) in hepatic endosomes: association with the
R Faure1, J F Gaulin, S Bourgoin
1Département de médecine, Centre de Recherche du CHUL, Université Laval, Ste-Foy, Québec, Canada. Robert.Faure@crchul.ulaval.ca
Abstract:
A pool of MAPK was found in hepatic plasma membrane (PM) and endosomes (ENs). After injection of a single dose of EGF (10 microg/100 g body weight), MAPK was detected in EGF receptor (EGFR) immunoprecipitates prepared from ENs. MAPK was detected in a time-dependent manner in EGFR immunoprecipitates that was coincident with the progressive concentration of the EGFR. The EGFR-associated MAPK was also detected by using an anti-phospho-MAPK suggesting that it was active. MAPK was present in wheat-germ agglutinin (WGA) eluates prepared from ENs and was maximally tyrosine-phosphorylated at the time peak of EGFR internalization. MAPK therefore is compartmentalized in PM and ENs of rat liver. A fraction of the endosomal MAPK was found to be associated with the internalized EGFR complexes, suggesting that it plays a role in the control of the EGFR activity at this locus.
Insights
Mitogen-activated protein kinase (MAPK) is located in liver cells and associates with the epidermal growth factor receptor (EGFR) during internalization. This suggests MAPK plays a role in regulating EGFR activity within endosomes.
Area of Science:
- Cellular Biology
- Molecular Signaling
- Hepatology
Background:
- Mitogen-activated protein kinase (MAPK) is a key signaling molecule.
- Epidermal growth factor receptor (EGFR) signaling is crucial for cellular processes.
- MAPK and EGFR interactions are implicated in various cellular functions.
Purpose of the Study:
- To investigate the localization and activity of MAPK in relation to EGFR signaling in rat liver.
- To determine if MAPK associates with internalized EGFR complexes.
Main Methods:
- Immunoprecipitation of EGFR from hepatic endosomes.
- Detection of MAPK and phospho-MAPK using specific antibodies.
- Wheat germ agglutinin (WGA) elution from endosomes.
Main Results:
- MAPK was found in hepatic plasma membrane and endosomes.
- Activated MAPK was detected in EGFR immunoprecipitates from endosomes in a time-dependent manner.
- Endosomal MAPK associated with internalized EGFR complexes, with peak phosphorylation coinciding with EGFR internalization.
Conclusions:
- MAPK is compartmentalized in rat liver plasma membrane and endosomes.
- A fraction of endosomal MAPK is associated with internalized EGFR.
- This association suggests a role for MAPK in controlling EGFR activity within endosomes.