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CDH1 regulates E2F1 degradation in response to differentiation signals in keratinocytes

The E2F1 transcription factor plays key roles in skin homeostasis. In the epidermis, E2F1 expression is essential for normal proliferation of undifferentiated keratinocytes, regeneration after injury and DNA repair following UV radiation-induced photodamage. Abnormal E2F1 expression promotes nonmela...

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Autores principales: Singh, Randeep K., Dagnino, Lina
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Impact Journals LLC 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5354885/
https://www.ncbi.nlm.nih.gov/pubmed/27903963
http://dx.doi.org/10.18632/oncotarget.13636
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author Singh, Randeep K.
Dagnino, Lina
author_facet Singh, Randeep K.
Dagnino, Lina
author_sort Singh, Randeep K.
collection PubMed
description The E2F1 transcription factor plays key roles in skin homeostasis. In the epidermis, E2F1 expression is essential for normal proliferation of undifferentiated keratinocytes, regeneration after injury and DNA repair following UV radiation-induced photodamage. Abnormal E2F1 expression promotes nonmelanoma skin carcinoma. In addition, E2F1 must be downregulated for proper keratinocyte differentiation, but the relevant mechanisms involved remain poorly understood. We show that differentiation signals induce a series of post-translational modifications in E2F1 that are jointly required for its downregulation. Analysis of the structural determinants that govern these processes revealed a central role for S403 and T433. In particular, substitution of these two amino acid residues with non-phosphorylatable alanine (E2F1 ST/A) interferes with E2F1 nuclear export, K11- and K48-linked polyubiquitylation and degradation in differentiated keratinocytes. In contrast, replacement of S403 and T433 with phosphomimetic aspartic acid to generate a pseudophosphorylated E2F1 mutant protein (E2F1 ST/D) generates a protein that is regulated in a manner indistinguishable from that of wild type E2F1. Cdh1 is an activating cofactor that interacts with the anaphase-promoting complex/cyclosome (APC/C) ubiquitin E3 ligase, promoting proteasomal degradation of various substrates. We found that Cdh1 associates with E2F1 in keratinocytes. Inhibition or RNAi-mediated silencing of Cdh1 prevents E2F1 degradation in response to differentiation signals. Our results reveal novel regulatory mechanisms that jointly modulate post-translational modifications and downregulation of E2F1, which are necessary for proper epidermal keratinocyte differentiation.
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spelling pubmed-53548852017-04-24 CDH1 regulates E2F1 degradation in response to differentiation signals in keratinocytes Singh, Randeep K. Dagnino, Lina Oncotarget Research Paper The E2F1 transcription factor plays key roles in skin homeostasis. In the epidermis, E2F1 expression is essential for normal proliferation of undifferentiated keratinocytes, regeneration after injury and DNA repair following UV radiation-induced photodamage. Abnormal E2F1 expression promotes nonmelanoma skin carcinoma. In addition, E2F1 must be downregulated for proper keratinocyte differentiation, but the relevant mechanisms involved remain poorly understood. We show that differentiation signals induce a series of post-translational modifications in E2F1 that are jointly required for its downregulation. Analysis of the structural determinants that govern these processes revealed a central role for S403 and T433. In particular, substitution of these two amino acid residues with non-phosphorylatable alanine (E2F1 ST/A) interferes with E2F1 nuclear export, K11- and K48-linked polyubiquitylation and degradation in differentiated keratinocytes. In contrast, replacement of S403 and T433 with phosphomimetic aspartic acid to generate a pseudophosphorylated E2F1 mutant protein (E2F1 ST/D) generates a protein that is regulated in a manner indistinguishable from that of wild type E2F1. Cdh1 is an activating cofactor that interacts with the anaphase-promoting complex/cyclosome (APC/C) ubiquitin E3 ligase, promoting proteasomal degradation of various substrates. We found that Cdh1 associates with E2F1 in keratinocytes. Inhibition or RNAi-mediated silencing of Cdh1 prevents E2F1 degradation in response to differentiation signals. Our results reveal novel regulatory mechanisms that jointly modulate post-translational modifications and downregulation of E2F1, which are necessary for proper epidermal keratinocyte differentiation. Impact Journals LLC 2016-11-26 /pmc/articles/PMC5354885/ /pubmed/27903963 http://dx.doi.org/10.18632/oncotarget.13636 Text en Copyright: © 2017 Singh and Dagnino http://creativecommons.org/licenses/by/3.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Paper
Singh, Randeep K.
Dagnino, Lina
CDH1 regulates E2F1 degradation in response to differentiation signals in keratinocytes
title CDH1 regulates E2F1 degradation in response to differentiation signals in keratinocytes
title_full CDH1 regulates E2F1 degradation in response to differentiation signals in keratinocytes
title_fullStr CDH1 regulates E2F1 degradation in response to differentiation signals in keratinocytes
title_full_unstemmed CDH1 regulates E2F1 degradation in response to differentiation signals in keratinocytes
title_short CDH1 regulates E2F1 degradation in response to differentiation signals in keratinocytes
title_sort cdh1 regulates e2f1 degradation in response to differentiation signals in keratinocytes
topic Research Paper
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5354885/
https://www.ncbi.nlm.nih.gov/pubmed/27903963
http://dx.doi.org/10.18632/oncotarget.13636
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