The SQSTM1/p62 UBA domain regulates Ajuba localisation, degradation and NF-κB signalling function

The LIM-domain containing protein Ajuba and the scaffold protein SQSTM1/p62 regulate signalling of NF-κB, a transcription factor involved in osteoclast differentiation and survival. The ubiquitin-associated domain of SQSTM1/p62 is frequently mutated in patients with Paget’s disease of bone. Here, we...

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Autores principales:	Melanie A. Sultana, Carmel Cluning, Wai-Sin Kwong, Nicole Polain, Nathan J. Pavlos, Thomas Ratajczak, John P. Walsh, Jiake Xu, Sarah L. Rea
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/ce95db131b1e48aea8e11c033670fb12
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spelling	oai:doaj.org-article:ce95db131b1e48aea8e11c033670fb122021-11-11T07:14:36ZThe SQSTM1/p62 UBA domain regulates Ajuba localisation, degradation and NF-κB signalling function1932-6203https://doaj.org/article/ce95db131b1e48aea8e11c033670fb122021-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC8568271/?tool=EBIhttps://doaj.org/toc/1932-6203The LIM-domain containing protein Ajuba and the scaffold protein SQSTM1/p62 regulate signalling of NF-κB, a transcription factor involved in osteoclast differentiation and survival. The ubiquitin-associated domain of SQSTM1/p62 is frequently mutated in patients with Paget’s disease of bone. Here, we report that Ajuba activates NF-κB activity in HEK293 cells, and that co-expression with SQSTM1/p62 inhibits this activation in an UBA domain-dependent manner. SQSTM1/p62 regulates proteins by targeting them to the ubiquitin-proteasome system or the autophagy-lysosome pathway. We show that Ajuba is degraded by autophagy, however co-expression with SQSTM1/p62 (wild type or UBA-deficient) protects Ajuba levels both in cells undergoing autophagy and those exposed to proteasomal stress. Additionally, in unstressed cells co-expression of SQSTM1/p62 reduces the amount of Ajuba present in the nucleus. SQSTM1/p62 with an intact ubiquitin-associated domain forms holding complexes with Ajuba that are not destined for degradation yet inhibit signalling. Thus, in situations with altered levels and localization of SQSTM1/p62 expression, such as osteoclasts in Paget’s disease of bone and various cancers, SQSTM1/p62 may compartmentalize Ajuba and thereby impact its cellular functions and disease pathogenesis. In Paget’s, ubiquitin-associated domain mutations may lead to increased or prolonged Ajuba-induced NF-κB signalling leading to increased osteoclastogenesis. In cancer, Ajuba expression promotes cell survival. The increased levels of SQSTM1/p62 observed in cancer may enhance Ajuba-mediated cancer cell survival.Melanie A. SultanaCarmel CluningWai-Sin KwongNicole PolainNathan J. PavlosThomas RatajczakJohn P. WalshJiake XuSarah L. ReaPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 16, Iss 11 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Melanie A. Sultana Carmel Cluning Wai-Sin Kwong Nicole Polain Nathan J. Pavlos Thomas Ratajczak John P. Walsh Jiake Xu Sarah L. Rea The SQSTM1/p62 UBA domain regulates Ajuba localisation, degradation and NF-κB signalling function
description	The LIM-domain containing protein Ajuba and the scaffold protein SQSTM1/p62 regulate signalling of NF-κB, a transcription factor involved in osteoclast differentiation and survival. The ubiquitin-associated domain of SQSTM1/p62 is frequently mutated in patients with Paget’s disease of bone. Here, we report that Ajuba activates NF-κB activity in HEK293 cells, and that co-expression with SQSTM1/p62 inhibits this activation in an UBA domain-dependent manner. SQSTM1/p62 regulates proteins by targeting them to the ubiquitin-proteasome system or the autophagy-lysosome pathway. We show that Ajuba is degraded by autophagy, however co-expression with SQSTM1/p62 (wild type or UBA-deficient) protects Ajuba levels both in cells undergoing autophagy and those exposed to proteasomal stress. Additionally, in unstressed cells co-expression of SQSTM1/p62 reduces the amount of Ajuba present in the nucleus. SQSTM1/p62 with an intact ubiquitin-associated domain forms holding complexes with Ajuba that are not destined for degradation yet inhibit signalling. Thus, in situations with altered levels and localization of SQSTM1/p62 expression, such as osteoclasts in Paget’s disease of bone and various cancers, SQSTM1/p62 may compartmentalize Ajuba and thereby impact its cellular functions and disease pathogenesis. In Paget’s, ubiquitin-associated domain mutations may lead to increased or prolonged Ajuba-induced NF-κB signalling leading to increased osteoclastogenesis. In cancer, Ajuba expression promotes cell survival. The increased levels of SQSTM1/p62 observed in cancer may enhance Ajuba-mediated cancer cell survival.
format	article
author	Melanie A. Sultana Carmel Cluning Wai-Sin Kwong Nicole Polain Nathan J. Pavlos Thomas Ratajczak John P. Walsh Jiake Xu Sarah L. Rea
author_facet	Melanie A. Sultana Carmel Cluning Wai-Sin Kwong Nicole Polain Nathan J. Pavlos Thomas Ratajczak John P. Walsh Jiake Xu Sarah L. Rea
author_sort	Melanie A. Sultana
title	The SQSTM1/p62 UBA domain regulates Ajuba localisation, degradation and NF-κB signalling function
title_short	The SQSTM1/p62 UBA domain regulates Ajuba localisation, degradation and NF-κB signalling function
title_full	The SQSTM1/p62 UBA domain regulates Ajuba localisation, degradation and NF-κB signalling function
title_fullStr	The SQSTM1/p62 UBA domain regulates Ajuba localisation, degradation and NF-κB signalling function
title_full_unstemmed	The SQSTM1/p62 UBA domain regulates Ajuba localisation, degradation and NF-κB signalling function
title_sort	sqstm1/p62 uba domain regulates ajuba localisation, degradation and nf-κb signalling function
publisher	Public Library of Science (PLoS)
publishDate	2021
url	https://doaj.org/article/ce95db131b1e48aea8e11c033670fb12
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The SQSTM1/p62 UBA domain regulates Ajuba localisation, degradation and NF-κB signalling function

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