Role of ubiquitination in IGF-1 receptor signaling and degradation.

BACKGROUND: The insulin-like growth factor 1 receptor (IGF-1R) plays numerous crucial roles in cancer biology. The majority of knowledge on IGF-1R signaling is concerned with its role in the activation of the canonical phosphatidyl inositol-3 kinase (PI3K)/Akt and MAPK/ERK pathways. However, the rol...

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Main Authors: Bita Sehat, Sandra Andersson, Radu Vasilcanu, Leonard Girnita, Olle Larsson
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2007-01-01
Series:PLoS ONE
Online Access:http://europepmc.org/articles/PMC1838569?pdf=render
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author Bita Sehat
Sandra Andersson
Radu Vasilcanu
Leonard Girnita
Olle Larsson
author_facet Bita Sehat
Sandra Andersson
Radu Vasilcanu
Leonard Girnita
Olle Larsson
author_sort Bita Sehat
collection DOAJ
description BACKGROUND: The insulin-like growth factor 1 receptor (IGF-1R) plays numerous crucial roles in cancer biology. The majority of knowledge on IGF-1R signaling is concerned with its role in the activation of the canonical phosphatidyl inositol-3 kinase (PI3K)/Akt and MAPK/ERK pathways. However, the role of IGF-1R ubiquitination in modulating IGF-1R function is an area of current research. In light of this we sought to determine the relationship between IGF-1R phosphorylation, ubiquitination, and modulation of growth signals. METHODOLOGY: Wild type and mutant constructs of IGF-1R were transfected into IGF-1R null fibroblasts. IGF-1R autophosphorylation and ubiquitination were determined by immunoprecipitation and western blotting. IGF-1R degradation and stability was determined by cyclohexamide-chase assay in combination with lysosome and proteasome inhibitors. PRINCIPAL FINDINGS: IGF-1R autophosphorylation was found to be an absolute requirement for receptor ubiquitination. Deletion of C-terminal domain had minimal effect on IGF-1 induced receptor autophosphorylation, however, ubiquitination and ERK activation were completely abolished. Cells expressing kinase impaired IGF-1R, exhibited both receptor ubiquitination and ERK phosphorylation, however failed to activate Akt. While IGF-1R mutants with impaired PI3K/Akt signaling were degraded mainly by the proteasomes, the C-terminal truncated one was exclusively degraded through the lysosomal pathway. CONCLUSIONS: Our data suggest important roles of ubiquitination in mediating IGF-1R signaling and degradation. Ubiquitination of IGF-1R requires receptor tyrosine kinase activity, but is not involved in Akt activation. In addition we show that the C-terminal domain of IGF-1R is a necessary requisite for ubiquitination and ERK phosphorylation as well as for proteasomal degradation of the receptor.
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spelling doaj.art-7e2cb66205a345e9b25ab69887a6e31d2022-12-22T01:03:24ZengPublic Library of Science (PLoS)PLoS ONE1932-62032007-01-0124e34010.1371/journal.pone.0000340Role of ubiquitination in IGF-1 receptor signaling and degradation.Bita SehatSandra AnderssonRadu VasilcanuLeonard GirnitaOlle LarssonBACKGROUND: The insulin-like growth factor 1 receptor (IGF-1R) plays numerous crucial roles in cancer biology. The majority of knowledge on IGF-1R signaling is concerned with its role in the activation of the canonical phosphatidyl inositol-3 kinase (PI3K)/Akt and MAPK/ERK pathways. However, the role of IGF-1R ubiquitination in modulating IGF-1R function is an area of current research. In light of this we sought to determine the relationship between IGF-1R phosphorylation, ubiquitination, and modulation of growth signals. METHODOLOGY: Wild type and mutant constructs of IGF-1R were transfected into IGF-1R null fibroblasts. IGF-1R autophosphorylation and ubiquitination were determined by immunoprecipitation and western blotting. IGF-1R degradation and stability was determined by cyclohexamide-chase assay in combination with lysosome and proteasome inhibitors. PRINCIPAL FINDINGS: IGF-1R autophosphorylation was found to be an absolute requirement for receptor ubiquitination. Deletion of C-terminal domain had minimal effect on IGF-1 induced receptor autophosphorylation, however, ubiquitination and ERK activation were completely abolished. Cells expressing kinase impaired IGF-1R, exhibited both receptor ubiquitination and ERK phosphorylation, however failed to activate Akt. While IGF-1R mutants with impaired PI3K/Akt signaling were degraded mainly by the proteasomes, the C-terminal truncated one was exclusively degraded through the lysosomal pathway. CONCLUSIONS: Our data suggest important roles of ubiquitination in mediating IGF-1R signaling and degradation. Ubiquitination of IGF-1R requires receptor tyrosine kinase activity, but is not involved in Akt activation. In addition we show that the C-terminal domain of IGF-1R is a necessary requisite for ubiquitination and ERK phosphorylation as well as for proteasomal degradation of the receptor.http://europepmc.org/articles/PMC1838569?pdf=render
spellingShingle Bita Sehat
Sandra Andersson
Radu Vasilcanu
Leonard Girnita
Olle Larsson
Role of ubiquitination in IGF-1 receptor signaling and degradation.
PLoS ONE
title Role of ubiquitination in IGF-1 receptor signaling and degradation.
title_full Role of ubiquitination in IGF-1 receptor signaling and degradation.
title_fullStr Role of ubiquitination in IGF-1 receptor signaling and degradation.
title_full_unstemmed Role of ubiquitination in IGF-1 receptor signaling and degradation.
title_short Role of ubiquitination in IGF-1 receptor signaling and degradation.
title_sort role of ubiquitination in igf 1 receptor signaling and degradation
url http://europepmc.org/articles/PMC1838569?pdf=render
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