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Wnt3a signal pathways activate MyoD expression by targeting cis-elements inside and outside its distal enhancer

Wnt proteins are secreted cytokines and several Wnts are expressed in the developing somites and surrounding tissues. Without proper Wnt stimulation, the organization of the dermomyotome and myotome can become defective. These Wnt signals received by somitic cells can lead to activation of Pax3/Pax7...

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Autores principales: Pan, Yu Chih, Wang, Xiao Wen, Teng, Han Feng, Wu, Yi Ju, Chang, Hsuan Chia, Chen, Shen Liang
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Portland Press Ltd. 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4370097/
https://www.ncbi.nlm.nih.gov/pubmed/25651906
http://dx.doi.org/10.1042/BSR20140177
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author Pan, Yu Chih
Wang, Xiao Wen
Teng, Han Feng
Wu, Yi Ju
Chang, Hsuan Chia
Chen, Shen Liang
author_facet Pan, Yu Chih
Wang, Xiao Wen
Teng, Han Feng
Wu, Yi Ju
Chang, Hsuan Chia
Chen, Shen Liang
author_sort Pan, Yu Chih
collection PubMed
description Wnt proteins are secreted cytokines and several Wnts are expressed in the developing somites and surrounding tissues. Without proper Wnt stimulation, the organization of the dermomyotome and myotome can become defective. These Wnt signals received by somitic cells can lead to activation of Pax3/Pax7 and myogenic regulatory factors (MRFs), especially Myf5 and MyoD. However, it is currently unknown whether Wnts activate Myf5 and MyoD through direct targeting of their cis-regulatory elements or via indirect pathways. To clarify this issue, in the present study, we tested the regulation of MyoD cis-regulatory elements by Wnt3a secreted from human embryonic kidney (HEK)-293T cells. We found that Wnt3a activated the MyoD proximal 6.0k promoter (P6P) only marginally, but highly enhanced the activity of the composite P6P plus distal enhancer (DE) reporter through canonical and non-canonical pathways. Further screening of the intervening fragments between the DE and the P6P identified a strong Wnt-response element (WRE) in the upstream −8 to −9k region (L fragment) that acted independently of the DE, but was dependent on the P6P. Deletion of a Pax3/Pax7-targeted site in the L fragment significantly reduced its response to Wnt3a, implying that Wnt3a activates the L fragment partially through Pax3/Pax7 action. Binding of β-catenin and Pax7 to their target sites in the DE and the L fragment respectively was also demonstrated by ChIP. These observations demonstrated the first time that Wnt3a can directly activate MyoD expression through targeting cis-elements in the DE and the L fragment.
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spelling pubmed-43700972015-04-07 Wnt3a signal pathways activate MyoD expression by targeting cis-elements inside and outside its distal enhancer Pan, Yu Chih Wang, Xiao Wen Teng, Han Feng Wu, Yi Ju Chang, Hsuan Chia Chen, Shen Liang Biosci Rep Original Paper Wnt proteins are secreted cytokines and several Wnts are expressed in the developing somites and surrounding tissues. Without proper Wnt stimulation, the organization of the dermomyotome and myotome can become defective. These Wnt signals received by somitic cells can lead to activation of Pax3/Pax7 and myogenic regulatory factors (MRFs), especially Myf5 and MyoD. However, it is currently unknown whether Wnts activate Myf5 and MyoD through direct targeting of their cis-regulatory elements or via indirect pathways. To clarify this issue, in the present study, we tested the regulation of MyoD cis-regulatory elements by Wnt3a secreted from human embryonic kidney (HEK)-293T cells. We found that Wnt3a activated the MyoD proximal 6.0k promoter (P6P) only marginally, but highly enhanced the activity of the composite P6P plus distal enhancer (DE) reporter through canonical and non-canonical pathways. Further screening of the intervening fragments between the DE and the P6P identified a strong Wnt-response element (WRE) in the upstream −8 to −9k region (L fragment) that acted independently of the DE, but was dependent on the P6P. Deletion of a Pax3/Pax7-targeted site in the L fragment significantly reduced its response to Wnt3a, implying that Wnt3a activates the L fragment partially through Pax3/Pax7 action. Binding of β-catenin and Pax7 to their target sites in the DE and the L fragment respectively was also demonstrated by ChIP. These observations demonstrated the first time that Wnt3a can directly activate MyoD expression through targeting cis-elements in the DE and the L fragment. Portland Press Ltd. 2015-03-18 /pmc/articles/PMC4370097/ /pubmed/25651906 http://dx.doi.org/10.1042/BSR20140177 Text en © 2015 The Author(s) This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC-BY) (http://creativecommons.org/licenses/by/3.0/) which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. http://creativecommons.org/licenses/by/3.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC-BY) (http://creativecommons.org/licenses/by/3.0/) which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Paper
Pan, Yu Chih
Wang, Xiao Wen
Teng, Han Feng
Wu, Yi Ju
Chang, Hsuan Chia
Chen, Shen Liang
Wnt3a signal pathways activate MyoD expression by targeting cis-elements inside and outside its distal enhancer
title Wnt3a signal pathways activate MyoD expression by targeting cis-elements inside and outside its distal enhancer
title_full Wnt3a signal pathways activate MyoD expression by targeting cis-elements inside and outside its distal enhancer
title_fullStr Wnt3a signal pathways activate MyoD expression by targeting cis-elements inside and outside its distal enhancer
title_full_unstemmed Wnt3a signal pathways activate MyoD expression by targeting cis-elements inside and outside its distal enhancer
title_short Wnt3a signal pathways activate MyoD expression by targeting cis-elements inside and outside its distal enhancer
title_sort wnt3a signal pathways activate myod expression by targeting cis-elements inside and outside its distal enhancer
topic Original Paper
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4370097/
https://www.ncbi.nlm.nih.gov/pubmed/25651906
http://dx.doi.org/10.1042/BSR20140177
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